From The National Radio Astronomy Observatory: “Astronomers Find Evidence for Most Powerful Pulsar in Distant Galaxy”

From The National Radio Astronomy Observatory

6.15.22 [Just found this]
Dave Finley
Public Information Officer
(505) 241-9210
dfinley@nrao.edu

Credit: Melissa Weiss, NRAO/AUI/NSF.

Astronomers analyzing data from the VLA Sky Survey (VLASS) have discovered one of the youngest known neutron stars — the superdense remnant of a massive star that exploded as a supernova. Images from the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) [below] indicate that bright radio emission powered by the spinning pulsar’s magnetic field has only recently emerged from behind a dense shell of debris from the supernova explosion.

Dame Susan Jocelyn Bell Burnell, discovered pulsars with radio astronomy. Jocelyn Bell at Mullard Radio Astronomy Observatory, University of Cambridge (UK), taken for the Daily Herald newspaper in 1968. Denied the Nobel.

The object, called VT 1137-0337, is in a dwarf galaxy 395 million light-years from Earth. It first appeared in a VLASS image made in January of 2018. It did not appear in an image of the same region made by the VLA’s FIRST Survey in 1998. It continued to appear in later VLASS observations in 2018, 2019, 2020, and 2022.

“What we’re most likely seeing is a pulsar wind nebula,” said Dillon Dong, a Caltech graduate student who will begin a Jansky Postdoctoral Fellowship at the National Radio Astronomy Observatory (NRAO) later this year. A pulsar wind nebula is created when the powerful magnetic field of a rapidly spinning neutron star accelerates surrounding charged particles to nearly the speed of light.

“Based on its characteristics, this is a very young pulsar — possibly as young as only 14 years, but no older than 60 to 80 years,” said Gregg Hallinan, Dong’s Ph.D advisor at Caltech.

The scientists reported their findings at the American Astronomical Society’s meeting in Pasadena, California.

Dong and Hallinan discovered the object in data from VLASS, an NRAO project that began in 2017 to survey the entire sky visible from the VLA — about 80 percent of the sky. Over a period of seven years, VLASS is conducting a complete scan of the sky three times, with one of the objectives to find transient objects. The astronomers found VT 1137-0337 in the first VLASS scan from 2018.

Comparing that VLASS scan to data from an earlier VLA sky survey called FIRST revealed 20 particularly luminous transient objects that could be associated with known galaxies.

“This one stood out because its galaxy is experiencing a burst of star formation, and also because of the characteristics of its radio emission,” Dong said. The galaxy, called SDSS J113706.18-033737.1, is a dwarf galaxy containing about 100 million times the mass of the Sun.

In studying the characteristics of VT 1137-0337, the astronomers considered several possible explanations, including a supernova, gamma ray burst, or tidal disruption event in which a star is shredded by a supermassive black hole. They concluded that the best explanation is a pulsar wind nebula.

In this scenario, a star much more massive than the Sun exploded as a supernova, leaving behind a neutron star.

Neutron Star L. Calçada/ European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europäische Südsternwarte] (EU) (CL)

Most of the original star’s mass was blown outward as a shell of debris. The neutron star spins rapidly, and as its powerful magnetic field sweeps through the surrounding space it accelerates charged particles, causing strong radio emission.

Initially, the radio emission was blocked from view by the shell of explosion debris. As that shell expanded, it became progressively less dense until eventually the radio waves from the pulsar wind nebula could pass through.

“This happened between the FIRST observation in 1998 and the VLASS observation in 2018,” Hallinan said.

Probably the most famous example of a pulsar wind nebula is the Crab Nebula in the constellation Taurus, the result of a supernova that shone brightly in the year 1054.

The Crab Nebula, Messier 1 by the Hubble Space Telescope – among the largest ever produced image with the Earth-orbiting observatory – gives the most detailed view so far of the. The Crab is arguably the single most interesting object, as well as one of the most studied, in all of astronomy. The image is the largest ever taken with Hubble’s WFPC2 workhorse camera. This composite image of the Crab Nebula was assembled by combining data from five telescopes spanning nearly the entire breadth of the electromagnetic spectrum. Credit: G. Dubner (University of Buenos Aires [Universidad de Buenos Aires] (AR)) National Aeronautics Space Agency, European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganization](EU), National Radio Astronomy Observatory /Associated Universities IncNational Science Foundation.

The Crab is readily visible today in small telescopes.

“The object we have found appears to be approximately 10,000 times more energetic than the Crab, with a stronger magnetic field,” Dong said. “It likely is an emerging ‘super Crab’,” he added.

While Dong and Hallinan consider VT 1137-0337 to most likely be a pulsar wind nebula, it also is possible that its magnetic field may be strong enough for the neutron star to qualify as a magnetar — a class of super-magnetic objects.

Iconic depiction of Magnetar in Westerlund 1 Credit L. Calçada/ The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europaiche Sûdsternwarte] (EU)(CL).

Magnetars are a leading candidate for the origin of the mysterious Fast Radio Bursts (FRBs) now under intense study.

“In that case, this would be the first magnetar caught in the act of appearing, and that, too, is extremely exciting,” Dong said.

Indeed some Fast Radio Bursts have been found to be associated with persistent radio sources, the nature of which also is a mystery. They bear a strong resemblance in their properties to VT 1137-0337, but have shown no evidence of strong variability.

“Our discovery of a very similar source switching on suggests that the radio sources associated with FRBs also may be luminous pulsar wind nebulae,” Dong said.

The astronomers plan to conduct further observations to learn more about the object and to monitor its behavior over time.

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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Please help promote STEM in your local schools.

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The National Radio Astronomy Observatory is a facility of The National Science Foundation, operated under cooperative agreement by The Associated Universities, Inc.

National Radio Astronomy Observatory Karl G Jansky Very Large Array located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

ngVLA, to be located near the location of the NRAO Karl G. Jansky Very Large Array site on the plains of San Agustin, fifty miles west of Socorro, NM, at an elevation of 6970 ft (2124 m) with additional mid-baseline stations currently spread over greater New Mexico, Arizona, Texas, and Mexico.

National Radio Astronomy Observatory Very Long Baseline Array.

The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL))/National Radio Astronomy Observatory/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

*The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

From The Universities Space Research Association : “The Distance to High-Velocity Cloud Complex M”

From The Universities Space Research Association

1.12.23

Traditional studies have placed High Velocity Clouds (HVCs) at great distances, in the Galactic halo and beyond. However new research suggests that the distance to HVC Complex M may be much closer—only 150 pc. These findings appear in a paper in The Astrophysical Journal [below] and presented at the 241st Meeting of the American Astronomical Society held in Seattle, Washington in January 2023.

Neutral hydrogen emission map of Complex M at a velocity of -85 km/s using a bandwidth of 20 km/s showing the connections between high-velocity “clouds” MI, MIIa, and MIIb, which appear to be density concentrations of a long, arched filament that extends from about (longitude, latitude) = (105°, 53°) to (196°, 55°). Also visible here is the intermediate-velocity arch, which may be a distinctly different feature. It begins at the base of the map around (longitude, latitude) = (115°, 37°) and crosses Complex M at (115°, 85°). Legend is brightness temperature in degrees Kelvin. Data are from the 100-m telescope in Effelsberg, Germany Credit: G. Verschuur.

The MPG Institute for Radio Astronomy[MPG Institut für Radioastronomie](DE)Effelsberg Radio Telescope- a radio telescope in the Ahr Hills (part of the Eifel) in Bad Münstereifel(DE).

The debate over the origin of HVC complexes goes back to the early days of radio astronomy in the 1960s. HVCs are concentrations of hydrogen gas with velocities that are not consistent with the regular rotation of the Milky Way Galaxy. Some HVC complexes could have been part of another galaxy that was disrupted by a close encounter with the Milky Way. Others may have been ejected from the Galaxy and are only now falling back.

In principle, a star behind an HI cloud might show HVC absorption features but a star in front would not. If the distances to the stars are known, the cloud should lie between them. This seemingly straightforward method is complicated by the relatively recent understanding that the HI gas is filamentary. Thus, the assumption of homogeneity over the entire radio beam for a feature with a cloud-like appearance does not seem to hold up. In fact, warnings against using a non-detection to constrain the distance have now appeared in the literature. As a result, the traditional absorption line studies can provide a well-defined upper limit but not a lower limit to the distance.

Even the customary naming of various HI structures can be confusing as data quality improves. What appeared to be isolated “clouds” in maps from old surveys might now be seen as parts of filaments as sensitivity, resolution, and dynamic range improve. New results show that the well- known HVCs designated as MI, MIIa, and MIIb, which appeared as clouds in earlier studies are, rather, local density concentrations or line-of-sight enhancements in a long, twisted filament that arcs across the sky (see figure). 

“These new surveys of interstellar hydrogen are such an improvement,” said Gerrit Verschuur, the lead author on the paper who has been studying HVCs for much of his career. “It’s the quality of the data that motivated us to take a new look at the old HVC problem.”

The data are from the l21-cm galactic neutral atomic hydrogen survey taken with the 100-m telescope in Effelsberg, Germany. MI is traveling faster than the surrounding gas. Recently, at least astronomically speaking, it caught up with and began interacting with/crashing into/passing through the arched filament of Complex M.

“If this is the case, we can use our distance to MI to bootstrap the distance to Complex M,” said Joan Schmelz, an astronomer at USRA and a co-author on the paper. “Both are much closer than previously thought – about 150 pc away.”

If the distance to the Complex M is 150 pc, then the mass is about 120 solar masses. If the original energy source were a supernova, this mass would be a combination of the matter from the explosion as well as gas swept up as the blast wave moved through interstellar space. The energy implied using the observed line-of-sight velocity, -85 km/s, is 8.4 × 1048 ergs. Integrating over 4π steradians, the total energy for a spherically symmetrical explosion is estimated to be 1.9 × 1050 ergs, well within the energy budget of a typical supernova.

The remaining neutron star would be the smoking gun required to prove the supernova model, but without a bright binary companion, a pulsar signature, or mass transfer, it would be all but invisible to us. As a result, other explanations for the larger-scale distribution of anomalous- velocity hydrogen are still very much in play, but the distance to Complex M gets us one step closer to unravelling the longstanding HVC mystery.

Science paper:
The Astrophysical Journal

See the full article here .

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The Universities Space Research Association is an independent, nonprofit research corporation where the combined efforts of in-house talent and university-based expertise merge to advance space science and technology.

SIGNIFICANCE & PURPOSE

The USRAwas founded in 1969, near the beginning of the Space Age, driven by the vision of two individuals, James Webb (NASA Administrator 1961-1968) and Frederick Seitz (National Academy of Sciences President 1962-1969). They recognized that the technical challenges of space would require an established research base to develop novel concepts and innovative technologies. Together, they worked to create USRA to satisfy not only the ongoing need for innovation in space, but also the need to involve society more broadly so the benefits of space activities would be realized.

From Astrobites : “Every Microsecond Counts for this Pulsar!”

From Astrobites

Title: Investigating the origin of optical and X-ray pulsations of the transitional millisecond pulsar PSR J1023+0038

Authors: G. Illiano, A.Papitto, F. Ambrosino, A. Miraval Zanon, et al. (20 additional authors)

First Author’s Institution: INAF-Osservatorio Astronomico di Roma (Astronomical Observatory of Rome; National Institute for Astrophysics)

Status: Accepted for publication in Astronomy & Astrophysics [closed access]

Pull out your stopwatches– today’s article pulls a whole lot of physics out of a time delay only 0.0002 seconds long! The radio astronomy community takes lots of interest in millisecond pulsars (MSPs), rapidly spinning neutron stars which emit radio waves from their poles. Pulsars are formed when a massive star undergoes a supernova explosion, leaving behind an extremely dense neutron star which spins slower as it ages. MSPs are the fastest-rotating pulsars, with the fastest pulsar rotating over 700 times a second!

NANOGrave Gravitational waves JPL-Caltech. Detecting gravitational waves using an array of pulsars (David Champion)

Dame Susan Jocelyn Bell Burnell, discovered pulsars with radio astronomy. Jocelyn Bell at Mullard Radio Astronomy Observatory, University of Cambridge(UK), taken for the Daily Herald newspaper in 1968. Denied the Nobel.

We believe that MSPs form from a pulsar in a binary orbit with a main sequence star like our Sun, a typical star which hasn’t collapsed yet – our Sun is light enough that it won’t form a pulsar, but rather a less dense white dwarf.

White dwarf star by Miriam Nielsen

The gravitational attraction of the heavy pulsar pulls the outer layers of stellar material from the star towards the pulsar. An accretion disk will form and rotate around the MSP, eventually falling onto the surface of – and transferring its angular momentum to – the pulsar, making it spin much faster. We’ve observed binary systems undergoing accretion, as well as MSPs in binary systems, but we’ve never directly seen a system transition between these two stages until the discovery of the pulsar J1023+0038 (J1023 for short), the subject of today’s paper.

J1023 was detected using optical telescopes, and was identified as a binary system with accretion onto a neutron star actively taking place. However, in 2007 radio observations of J1023 found a new periodic signal from a millisecond pulsar, and optical follow-up confirmed that the optical signatures of active accretion were gone. At some point J1023 had transitioned from an accreting state into a standard rotation-powered MSP making it the first confirmed transitional MSP!

In 2013 J1023 unexpectedly switched back to an accreting state: the optical and X-ray and gamma-ray emission got much brighter while the periodic radio emission became undetectable. J1023 has stayed in this state from 2013 until the time of writing (December 2022). These studies indicate that the transition from an accreting binary to MSP isn’t smooth; the system can wobble back and forth between states before it settles into becoming a full-time MSP.

Clocking Every Pulse

Figure 1- the optical pulse profile of J1023+0038, or the brightness of optical emission as a function of pulse phase. The profile is repeated twice for clarity. The two peaks making up the pulse profile are clearly visible. Adapted from Figure 1 of Ambrosino et al. 2017.

Previous studies [below] have found that in this accreting state, there are detectable optical pulses, or periodic bursts of brighter optical emission at the exact spin period of the neutron star. Figure 1 shows the pulse profile of the optical pulses, or the strength of the optical emission as a function of the rotational phase of the pulsar. We have also detected X-ray pulses from J1023 in its accreting state, and they randomly appear and disappear on the timescales of minutes, suggesting that whatever emission mechanism creates the X-rays is very turbulent. Follow-up studies [The Astrophysical Journal (below)] have shown that the optical and X-ray pulses appear and disappear almost perfectly in sync, so their emission mechanisms are likely very closely-related, but beyond that, no one really knows what those mechanisms could be!

Today’s authors aimed to get simultaneous observations at optical and X-ray wavelengths to learn more about how J1023 produces those types of emission. The previous observations used to study this system hinted at a time lag between the X-ray and optical pulses only fractions of a millisecond long, but the instruments lacked the timing precision to make a definitive finding. Today’s study oversaw the gradual transition to using the much more precise NICER X-ray observatory on the International Space Station and Aqueye+ photometer on the Copernicus telescope in Asiago, Italy – NICER has a timing error of a few nanoseconds, and Aqueye+ has a timing error of less than a nanosecond! 

NICER on the ISS

Aqueye+ photometer


Copernicus telescope in Asiago, Italy [Cima Ekar Observing Station]

Figure 2- the time lag between the X-ray and optical pulses in microseconds, as measured by different observatories on different dates; the y-axis moves forward in time from the bottom to the top of the figure. Figure 3 from today’s paper.

The authors measured the time delay between the X-ray and optical pulses using both the old and new observatories, and found consistent delays roughly 100-200 microseconds long – a confirmation that the time delay is real. Figure 2 shows the measured delays between X-ray and optical pulses using different observatories on different dates. Over time (moving from the bottom to the top of the figure), the average time delay between the pulses doesn’t change dramatically, but the usage of more precise observatories allows for better measurements of the time lag. After lots of these observations, the authors found that there’s no single value that consistently models the delay between the pulses, but they tend to fall around 200 microseconds. 

So, how can this measurement of the time lag help us understand the enigmatic nature of J1023? We know that the optical and X-ray pulse profiles are very similar, and that when the X-ray pulses turn off or turn back on, the optical pulses do the same almost immediately. The authors put forward the theory that despite the presence of the accretion disk around the pulsar, the pulsar is still rotating deep within this cloud of gas. We would not be able to see the periodic radio emission from this rotating pulsar, because the accretion disk around it blocks the radio emission from escaping. Rotating pulsars create pulsar winds, outflows of very energetic particles, which could still affect its environment even if the disk blocks us from seeing it.

The pulsar wind could clash into the inner edge of the accretion disk, creating a shock that would emit both X-rays and optical pulses, explaining the similarities between the two. Synchrotron emission, the type of emission that would be created by a shock like this, takes different amounts of time to be emitted depending on the frequency of the light being created, which could explain why the X-ray and optical pulses display a time lag. J1023 is clearly a very complicated and exciting system, and the clock is ticking until we make more discoveries; every microsecond counts!

Science papers:
Previous studies 2017
The Astrophysical Journal 2019
See the above science paper for instructive material with images.

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”

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Please help promote STEM in your local schools.

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What do we do?

Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.

Why read Astrobites?

Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.

Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

From The National Radio Astronomy Observatory: “The VLA Low-band Ionosphere and Transient Experiment (VLITE)”

From The National Radio Astronomy Observatory

12.20.22
Tracy Clarke | (U.S. Naval Research Laboratory) and the NRL VLITE Team

VCSS1 sky coverage plot.

Scientific exploration continues with the Very Large Array (VLA) [below] Low-band Ionosphere and Transient Experiment (VLITE), a commensal 340 MHz primary focus system that operates simultaneously with nearly all VLA Cassegrain receiver observations. VLITE’s DiFX correlator operates in parallel to WIDAR, providing simultaneous wide field of view, low frequency coverage of each VLA field. On 25 November 2022, VLITE turned eight years old and has progressed from a test system with 10 antennas to the current stable 18 antenna system that correlates both standard sidereal tracking observations as well as those observations taken in the on-the-fly mode used by the VLA Sky Survey (VLASS). During a typical year, VLITE records over 6000 hours of data that are pipeline processed and cataloged at the Naval Research Laboratory (NRL).

A key recent milestone is the measurement of a 2D primary beam response for VLITE that is applicable to the different observing bands. Using this beam model, VLITE data, including those associated with VLASS, can now be accurately corrected for the offset and rotating primary beam response. We have released the VLITE Commensal Sky Survey (VCSS) Epoch 1 Bright Source Catalog through collaboration with CIRADA. This catalog contains sources detected above 50 sigma (~150 mJy/beam, 10” < beam < 30”) from observations recorded in parallel with the first epoch of VLASS data. The figure illustrates the VCSS1 sky coverage plot. Colors correspond to local RMS noise values near cataloged sources. The average 1σ noise is 3 mJy bm−1. The small higher-noise tiles (e.g. RA ∼ 3 hrs, Dec ∼ −12o) are likely the result of gain errors in the primary calibration. The Galactic Plane is clearly visible, as are areas of increased noise when bright sources such as Cyg A and Cas A are in the primary beam sidelobes. White squares above the Dec -40° survey cutoff are regions where no VCSS1 images are available.

VLITE data has been used or cited in 44 refereed papers covering a diverse range of science from tidal disruption events and fast radio bursts to studies of active galactic nuclei and distant quasars. We would like to thank all the present and former NRAO staff and scientists who have made these milestones possible.

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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Please help promote STEM in your local schools.

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The National Radio Astronomy Observatory is a facility of The National Science Foundation, operated under cooperative agreement by The Associated Universities, Inc.

National Radio Astronomy Observatory Karl G Jansky Very Large Array located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

ngVLA, to be located near the location of the NRAO Karl G. Jansky Very Large Array site on the plains of San Agustin, fifty miles west of Socorro, NM, at an elevation of 6970 ft (2124 m) with additional mid-baseline stations currently spread over greater New Mexico, Arizona, Texas, and Mexico.

National Radio Astronomy Observatory Very Long Baseline Array.

The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL))/National Radio Astronomy Observatory/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

*The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

From The National Radio Astronomy Observatory: “Relativistic Ejecta in Broad-lined Type Ic Supernovae”

From The National Radio Astronomy Observatory

12.20.22
Alessandra Corsi | Texas Tech University

Shades of pink, purple and blue show light curves at 6 GHz of our Ic-BL SNe. Downward-pointing triangles mark non-detections. Filled circles mark detections. Other colors allow comparisons with other SNe. Credit: Corsi et al. (2022).

Stripped-envelope core-collapse supernovae (SNe) with high photospheric velocities (Ic-BL) are rare and energetic stellar explosions that challenge the standard explosion mechanism of massive stars. SNe Ic-BL are the only type of core-collapse events unambiguously linked to gamma-ray bursts (GRBs; Woosley & Bloom 2006). However, not all SNe Ic-BL make GRBs and the reason behind this remains a mystery.

Radio follow-up observations of SNe Ic-BL can probe the explosions’ fastest-moving ejecta largely free of geometry and viewing angle constraints that affect observations in gamma-rays. Measuring the fraction of SNe Ic-BL that output relativistic jets, and their kinetic energy via radio calorimetry, can directly test the predictions of GRB-SN progenitor and explosion models.

Motivated by the above, Corsi et al. (2022) conducted a search for relativistic explosions in a sample of 16 SNe Ic-BL observed with the Zwicky Transient Facility (Bellm et al. 2019), and discovered independently of a gamma-ray trigger.

Zwicky Transient Facility (ZTF) instrument installed on the 1.2m diameter Samuel Oschin Telescope at Palomar Observatory in California. Credit: Caltech Optical Observatories.

Caltech Palomar Samuel Oschin 48 inch Telescope, located in San Diego County, California, altitude 1712 m (5617 ft). Credit: Caltech.

This campaign, carried out using the Jansky VLA [below], doubled the sample previously presented in Corsi et al. (2016). Our results show that SNe Ic-BL like the GRB-associated SN 1998bw, SN 2003lw, SN 2010dh, or the relativistic SN 2009bb and iPTF17cw are intrinsically rare (see figure). However, the parameter space of SN 2006aj-like events (faint and fast-peaking radio emission; Soderberg et al. 2006) is left largely unconstrained, and systematically exploring it represents a promising line of future research.

The Legacy Survey of Space and Time on the Vera Rubin Observatory (Ivezic et al. 2019) will provide numerous discoveries of even the rarest type of explosive transients, such as the SNe Ic-BL discussed here.

The National Science Foundation NOIRLab National Optical Astronomy Observatory Vera C. Rubin Observatory [LSST] Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the Gemini South Telescope and Southern Astrophysical Research Telescope.

Recognizing them early (e.g., Villar et al. 2020), and enabling their prompt radio follow-up with the ngVLA [below] (Murphy 2018), could provide a unique opportunity for building a large statistical sample of SNe Ic-BL with deep radio observations. This sample could guide theoretical modeling in a more systematic fashion, beyond what has been achievable over the last 25 years.

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The National Radio Astronomy Observatory is a facility of The National Science Foundation, operated under cooperative agreement by The Associated Universities, Inc.

National Radio Astronomy Observatory Karl G Jansky Very Large Array located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

ngVLA, to be located near the location of the NRAO Karl G. Jansky Very Large Array site on the plains of San Agustin, fifty miles west of Socorro, NM, at an elevation of 6970 ft (2124 m) with additional mid-baseline stations currently spread over greater New Mexico, Arizona, Texas, and Mexico.

National Radio Astronomy Observatory Very Long Baseline Array.

The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL))/National Radio Astronomy Observatory/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

*The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

From The Green Bank Observatory : “Scientists Reveal Secrets to Burping Black Hole with the Green Bank Telescope”

Green Bank Radio Telescope, West Virginia, USA, now the center piece of the Green Bank Observatory, being cut loose by the National Science Foundation(US), supported by Breakthrough Listen Project, West Virginia University, and operated by the nonprofit Associated Universities, Inc..

From The Green Bank Observatory

12.6.22
Jill Malusky

The Green Bank Telescope (GBT) has revealed new information about mysterious radio bubbles surrounding a supermassive black hole.  

Observations by NASA’s Chandra X-ray Observatory (left image) and by GBO’s MUSTANG-2 instrument (right image) clearly show the enormous cavities (highlighted with gray circles) excavated by the powerful radio jets (green contours) expelled from the black hole at the center of galaxy cluster MS0735.

The National Aeronautics and Space Administration Chandra X-ray telescope.

The green contours in both images are from observations performed by the Naval Research Laboratory’s VLA Low-band Ionosphere and Transient Experiment (VLITE) back end used on the National Radio Astronomy Observatory’s (NRAO) Very Large Array (VLA).

National Radio Astronomy Observatory Karl G Jansky Very Large Array located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

In a new paper [below] studying the galaxy cluster MS0735, “We’re looking at one of the most energetic outbursts ever seen from a supermassive black hole,” says Jack Orlowski-Scherer, lead author on this publication, “This is what happens when you feed a black hole and it violently burps out a giant amount of energy.” At the time of the study, Jack was a graduate student at the University of Pennsylvania, and is now a research fellow at McGill University in Montreal, Quebec.

Supermassive black holes are found deep within the centers of the enormous galaxies at the heart of galaxy clusters. The plasma filled atmospheres of galaxy clusters are unbelievably hot – about 50 million degrees celsius – but these hot temperatures usually cool over time, allowing new stars to form. Sometimes, the black hole reheats the gas surrounding it through violent outbursts jetting from its center, preventing cooling and star formation, in a process called feedback. 

These powerful jets carve out immense cavities within the hot cluster medium, pushing that hot gas farther from the cluster center and replacing it with radio-emitting bubbles. Displacing such a large volume of gas requires an enormous amount of energy (several percent of the total thermal energy in the cluster gas) , and understanding where this energy comes from is of great interest to astrophysicists. By learning more about what’s left behind filling in these cavities, astronomers can begin to deduce what caused them in the first place. 

The team of astronomers used the MUSTANG-2 receiver on the GBT to image MS0735 using the Sunyaev-Zeldovich (SZ) effect, a subtle distortion of the cosmic microwave background (CMB) radiation due to scattering by hot electrons in the cluster gas.

(2) MUSTANG-2 receiver on the GBT

For context, the CMB was emitted 380 thousand years after the Big Bang, and is the afterglow of the origin of our universe 13.8 billion years ago. Around 90 GHz, where MUSTANG-2 observes, the SZ effect signal primarily measures thermal pressure. 

“With the power of MUSTANG-2, we are able to see into these cavities and start to determine precisely what they are filled with, and why they don’t collapse under pressure,” elaborates Tony Mroczkowski, an astronomer with the European Southern Observatory who was part of this new research.

These new findings are the deepest high-fidelity SZ imaging yet of the thermodynamic state of cavities in a galaxy cluster, reinforcing previous discoveries that at least a portion of the pressure support in the cavities is due to non-thermal sources, such as relativistic particles, cosmic rays, and turbulence, as well as a small contribution from magnetic fields. “We knew this was an exciting system when we studied the radio core and lobes at low frequencies, but we are only now beginning to see the full picture”, explains co-author Tracy Clarke, an astronomer at the U.S. Naval Research Laboratory and VLITE Project Scientist who co-authored a previous radio study of this system.

In contrast to earlier research, new imaging produced by the GBT considers the possibility that the pressure support within the bubbles could be more nuanced than previously thought, mixing both thermal and non-thermal components. In addition to the radio observations, the team incorporated existing X-ray observations from NASA’s Chandra X-ray Observatory, which provide a complementary view of the gas seen by MUSTANG-2.

Future observations across multiple frequencies can establish more precisely the nature of how exotic the black hole eruption is. “This work will help us better understand the physics of galaxy clusters, and the cooling flow feedback problem that has vexed many of us for some time,” adds Orlowski-Scherer.

Read more about this work published in the latest issue of the journal of Astronomy & Astrophysics.
https://www.aanda.org/articles/aa/full_html/2022/11/aa44547-22/aa44547-22.html
See the science paper for instructive material with images.

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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Mission Statement

The Green Bank Observatory enables leading edge research at radio wavelengths by offering telescope, facility and advanced instrumentation access to the astronomy community as well as to other basic and applied research communities. With radio astronomy as its foundation, the Green Bank Observatory is a world leader in advancing research, innovation, and education.

Green Bank Observatory campus

History

60 years ago, the trailblazers of American radio astronomy declared this facility their home, establishing the first ever National Radio Astronomy Observatory within the United States and the first ever national laboratory dedicated to open access science. Today their legacy is alive and well.

From The National Radio Astronomy Observatory: “Silent as the Night – Why Radio Astronomy Doesn’t Listen to the Sky”

From The National Radio Astronomy Observatory

12.8.22
Brian Koberlein

Credit: NRAO/AUI/NSF.

In the 1997 movie Contact, Ellie Arroway is a young radio astronomer played by Jodie Foster. Ellie’s on a mission to discover alien life, and in one famous scene filmed at the Very Large Array [below], she sits at the edge of the observatory, listening to the radio sounds of the sky with antenna dishes in the background. It’s a wonderful cinematic moment highlighting Ellie’s lonely search for truth and has become so iconic that many visitors to the VLA take “that shot” of themselves wearing headphones in front of a radio dish. But as beautifully poetic as the scene is, it is Hollywood magic, not hard science. The radio signals from Ellie’s headphones and computer would interfere with the observatory’s sensitive equipment and radio astronomers don’t listen to the sky.

The idea that radio astronomers listen to celestial objects is perhaps the biggest misconception in radio astronomy. And to some degree it’s understandable. People listen to the radio all the time, so surely radio astronomers must do the same. But the sounds we hear on the radio aren’t the sounds of radio itself. They are converted from electrical signals. Sound waves require a medium such as air to travel through, and since space is essentially a vacuum, sounds can’t travel through space. If astronomers did listen to the sky, all they would hear is silence.

Radio is a form of light. It’s just like visible light, but with a much longer wavelength. While visible light has a wavelength on the scale of atoms, radio light has wavelengths ranging from about the thickness of a pencil lead to more than the length of a bus.

Because radio wavelengths are on the human scale, the technology of radio astronomy is often very different from that of optical astronomy. There are broad similarities. Both optical and radio astronomy use reflective surfaces to focus light onto a detector or receiver, which then converts the light into a digital signal. Astronomers can then use this digital signal to create astronomical images. But because radio wavelengths are so much longer than visible wavelengths, we have to achieve this feat in different ways.

One key factor is the size of the reflector. Generally, the larger your reflector or mirror, the more light you can focus and the sharper and brighter your image. This is why the best optical telescopes have mirrors several meters in diameter. But the size of your reflector must scale to that of your wavelength. Since radio waves are thousands of times longer than visible waves, a radio telescope mirror would need to be larger than Manhattan. That isn’t something we can build, so instead, we create arrays of smaller dishes. Each antenna dish acts like a piece of a larger mirror. Astronomers can then simulate a city-wide dish by combining data from the array of smaller dishes.

Another factor is that radio light is often much fainter than visible light, and there are many things that create radio light. This means that radio telescopes need to be protected from everyday objects such as cell phones and computer equipment that emit radio light. The antenna receivers must also be extremely cold. Objects at room temperature emit lots of faint radio light which can affect the accuracy of observational data, so the receivers and other electronics of a radio telescope must be supercooled to convert radio light into a digital signal.

Of course, once astronomers have their data, they can always convert that data into sound. This is most famously done with pulsars, where the electric bursts of energy from a neutron star are converted to audible pops. Astronomers have also converted phenomena such as the turbulent aurora of Jupiter, or the wail of a distant nebula. These sounds can give us an emotional connection to the cosmos, but just like the scene from Contact, they are merely a poetic interpretation of the radio light we capture.

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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The National Radio Astronomy Observatory is a facility of The National Science Foundation, operated under cooperative agreement by The Associated Universities, Inc.

National Radio Astronomy Observatory Karl G Jansky Very Large Array located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

ngVLA, to be located near the location of the NRAO Karl G. Jansky Very Large Array site on the plains of San Agustin, fifty miles west of Socorro, NM, at an elevation of 6970 ft (2124 m) with additional mid-baseline stations currently spread over greater New Mexico, Arizona, Texas, and Mexico.

National Radio Astronomy Observatory Very Long Baseline Array.

The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL))/National Radio Astronomy Observatory/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

*The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

From “Astronomy Magazine” : “What the image of the Milky Way’s black hole really shows”

From “Astronomy Magazine”

11.11.22 [Just now in social media.]
Katie McCormick

The massive object at the galaxy’s center is invisible. But this year’s picture of the swirling plasma around its edges will help to reveal more about the galaxy’s history and evolution.

To create the first image of the Milky Way’s black hole, scientists ran numerous simulations of the swirling envelope of plasma that encircles it. This clip shows the version of the animated computer model that seemed to best mirror the radio wave data collected by the Event Horizon Telescope. Credit: Abhishek Joshi/UIUC.
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Event Horizon Telescope Array

The locations of the radio dishes that will be part of the Event Horizon Telescope array. Image credit: Event Horizon Telescope. via University of Arizona.

University of Arizona Radio Observatory at NOAO Kitt Peak National Observatory, AZ., U Arizona Department of Astronomy and Steward Observatory at altitude 2,096 m (6,877 ft).

U Arizona 12 meter Radio Telescope

ESO operates the Atacama Pathfinder Experiment, APEX, for The MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie](DE) at one of the highest observatory sites on Earth, at an elevation of 5100 metres, high on the Chajnantor plateau in Chile’s Atacama region.

Combined Array for Research in Millimeter-wave Astronomy (CARMA Array for Research in Millimeter-wave Astronomy(US)), in the Inyo Mountains to the east of the California Institute of Technology Owens Valley Radio Observatory, at a site called Cedar Flat, Altitude 1,222 m (4,009 ft), relocated to Owens Valley Radio Observatory, Altitude 1,222 m (4,009 ft).

NAOJ Atacama Submillimeter Telescope Experiment (ASTE) deployed to its site on Pampa La Bola, near Cerro Chajnantor and the Llano de Chajnantor, Observatory in northern Chile, Altitude 4,800 m (15,700 ft).

California Institute of Technology Submillimeter Observatory on Mauna Kea, Hawai’i, Altitude 4,205 m (13,796 ft).

IRAM-Institut de Radio Astronomie Millimétrique Plateau de Bure interferometer (FR) at an elevation of 2550 meters, the telescope currently consists of ten antennas, each 15 meters in diameter.interferometer, Located in the French Alpes on the wide and isolated Plateau de Bure at an elevation of 2550 meters.

East Asian Observatory James Clerk Maxwell Telescope MaunaKea Hawai’i, altitude 4207 m (13802 ft) above sea level.

The University of Massachusetts Amherst and Mexico’s Instituto Nacional de Astrofísica, Óptica y Electrónica MX Large Millimeter Telescope Alfonso Serrano, Mexico, at an altitude of 4850 meters on top of the Sierra Negra.

CFA Harvard Smithsonian Submillimeter Array on MaunaKea, Hawai’i Altitude 4205 m (13796 ft).

The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europäische Südsternwarte](EU)(CL)/National Radio Astronomy Observatory/National Astronomical Observatory of Japan(JP) ALMA Observatory (CL).

South Pole Telescope SPTPOL. The SPT collaboration is made up of over a dozen (mostly North American) institutions, including The University of Chicago; The University of California Berkeley; Case Western Reserve University; Harvard/Smithsonian Astrophysical Observatory; The University of Colorado-Boulder; McGill University(CA); The University of Illinois, Urbana-Champaign; The University of California-Davis; Ludwig Maximilians Universität München(DE); DOE’s Argonne National Laboratory; and The National Institute for Standards and Technology. It is funded by the National Science Foundation

About the Event Horizon Telescope (EHT)

The EHT consortium consists of 13 stakeholder institutes; The Academia Sinica Institute of Astronomy & Astrophysics [中央研究院天文及天文物理研究所](TW) , The University of Arizona, The University of Chicago, The East Asian Observatory, Goethe University Frankfurt [Goethe-Universität](DE), Institut de Radioastronomie Millimétrique, Large Millimeter Telescope, The MPG Institute for Radio Astronomy[MPG Institut für Radioastronomie](DE), MIT Haystack Observatory, The National Astronomical Observatory of Japan[[国立天文台](JP), The Perimeter Institute for Theoretical Physics (CA), Radboud University [Radboud Universiteit](NL) and The Center for Astrophysics | Harvard & Smithsonian.
_________________________________________

Black holes keep their secrets close. They imprison forever anything that enters. Light itself can’t escape a black hole’s hungry pull.

It would seem, then, that a black hole should be invisible — and taking its picture impossible. So great fanfare accompanied the release in 2019 of the first image of a black hole [Messier 87*].

Messier 87*, The first image of the event horizon of a black hole. This is the supermassive black hole at the center of the galaxy Messier 87. Image via The Event Horizon Telescope Collaboration released on 10 April 2019 via National Science Foundation.

Now iconic image of Katie Bouman-Harvard Smithsonian Astrophysical Observatory after the image of Messier 87* was achieved. Headed from Harvard to Caltech as an Assistant Professor. On the committee for the next iteration of the EHT.

Katie Bouman of Harvard Smithsonian Observatory for Astrophysics, headed to California Institute of Technology , with EHT hard drives from Messier 87*.

Then, in spring 2022, astronomers unveiled another black hole photo — this time of the one at the center of our own Milky Way.

This is the first image of Sagittarius A* – the supermassive black hole at the center of the Milky Way. Credit: EHT Collaboration.

The image shows an orange, donut-shaped blob that looks remarkably similar to the earlier picture of the black hole in the center of galaxy Messier 87. But the Milky Way’s black hole, Sagittarius A*, is actually much smaller than the first and was more difficult to see, since it required peering through the hazy disk of our galaxy. So even though the observations of our own black hole were conducted at the same time as M87’s, it took three additional years to create the picture. Doing so required an international collaboration of hundreds of astronomers, engineers and computer scientists, and the development of sophisticated computer algorithms to piece together the image from the raw data.

The new image of the black hole Sagittarius A*, confirms and refines previous predictions of its size and orientation. The mass of the black hole determines its size, or what scientists call its gravitational diameter. The point at which no light can escape from the black hole, called the event horizon, is determined by this mass and by the spin of the black hole. Hot plasma speeds around the massive object in the accretion disk, emitting radio waves. Those radio waves are bent and warped by gravity (through the effect of “gravitational lensing”) to produce the image of the orange outer circles. The black hole shadow and emission ring shown here are gravitationally-lensed projections of the far-side of the black hole’s event horizon and accretion disk, respectively.

These “photos” do not, of course, directly show a black hole, defined as the region of space inside a point-of-no-return barrier known as an event horizon. They actually record portions of the flat pancake of hot plasma swirling around the black hole at high speeds in what’s known as the accretion disk. The plasma is composed of high-energy charged particles. As plasma spirals around the black hole, its accelerating particles emit radio waves. The blurry orange ring seen in the images are an elaborate reconstruction of these radio waves captured by eight telescopes scattered around the Earth, collectively known as the Event Horizon Telescope (EHT).

The latest image tells the tale of the epic journey of radio waves from the center of the Milky Way, providing unprecedented detail about Sagittarius A*. The image also constitutes “one of the most important visual proofs of General Relativity,” our current best theory of gravity, says Sera Markoff, an astrophysicist at the University of Amsterdam and member of the EHT collaboration.

Studying supermassive black holes such as Sagittarius A* will help scientists learn more about how galaxies evolve over time and how they congregate in vast clusters across the universe.

From the galactic core

Sagittarius A* is 1,600 times smaller than Messier 87* imaged in 2019, and is also about 2,100 times closer to Earth. That means the two black holes appear to be about the same size on the sky. Geoffrey Bower, an EHT project scientist at the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan, says that the resolution required to see Sagittarius A* from Earth is the same as would be required to take a picture of an orange on the surface of the Moon.

The center of our galaxy is 26,000 light-years away from us, so the radio waves collected to create this image were emitted around the time that one of the earliest-known permanent human settlements was constructed. The radio waves’ voyage began when they were first emitted from particles in the black hole’s accretion disk. With a wavelength of about 1 mm, the radiation traveled toward Earth relatively undisturbed by the intervening galactic gas and dust. If the wavelength were much shorter, like visible light, the radio waves would have been scattered by the dust. If the wavelength were much longer, the waves would have been bent by charged clouds of plasma, distorting the image.

Finally, after the 26,000-year trek, the radio waves were picked up and recorded at the radio observatories distributed across our planet. The large geographic separation between the observatories was essential — it allowed the consortium of researchers to detect extremely subtle differences in the radio waves collected at each site through a process called interferometry. These small differences are used to deduce the minuscule differences in the distance each radio wave traveled from its source. Using computer algorithms, the scientists managed to decode the path-length differences of the radio waves to reconstruct the shape of the object that emitted them.

The latest black hole image was created using a technique called interferometry, in which the radio waves emitted by the black hole and collected by eight telescopes located around the world are compared. If two sites collected waves that were “in-phase”, meaning the waves’ peaks lined up with one another, then the two waves would add together to create a bright spot on the image. If, on the other hand, the waves were out-of-phase, meaning one wave’s peak lined up with the other’s trough, the waves would cancel each other, producing a dark spot in the image. Working together, the telescopes are able to collect more detailed data than any one could alone.

Researchers put all this into a false-color image, where orange represents high-intensity radio waves and black represents low-intensity. “But each telescope only picks up a tiny fraction of the radio signal,” explains Fulvio Melia, an astrophysicist at University of Arizona who has written about our galaxy’s supermassive black hole [Annual Review of Astronomy and Astrophysics (below)] . Because we’re missing much of the signal, “instead of seeing a crystal clear photo, you see something that’s a little foggy … a little blurred.”

The image helps reveal more about the black hole’s event horizon — the closest point to which anything can approach the black hole without being sucked in. Beyond the event horizon, not even light can escape.

From the image, scientists have been able to better estimate the size of the event horizon and deduce that the accretion disk is tilted by more than 40 degrees from the Milky Way’s disk, so that we’re seeing the round face of the flat accretion disk, rather than the thin sliver of its edge.

But even if the black hole’s accretion disk were oriented edge-on relative to Earth, the gravity around the black hole warps the space around it so much that light emitted from the backside of the black hole would be bent around to come toward us, making a ringlike image regardless of its orientation. So, how do scientists know its orientation? Because the ring is mostly round; if we were viewing the accretion disk edge-on, then the ring would be more squished and oblong.

Markoff thinks that this new ability to look into the heart of our galaxy will help to fill in gaps in our understanding of the evolution of galaxies and the large-scale structure of the universe. A dense, massive object such as a black hole at the center of a galaxy influences the movements of the stars and dust near it, and that influences how the galaxy changes over time. Properties of the black hole, such as in which direction it spins, depend on the history of its collisions — with stars or other black holes, perhaps. “A lot of people … look at the sky and think of it all as static, right? But it’s not. It’s a big ecosystem of stuff that’s evolving,” Markoff says.

So far, the fact that the image matches the scientists’ expectations so precisely makes it an important confirmation of current theories of physics. “This has been a prediction that we’ve had for two decades,” Bower says, “that we would see a ring of this scale. But, you know, seeing is believing.”

Science paper:
Annual Review of Astronomy and Astrophysics
See the science paper for instructive material with images.

See the full article here .

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Please help promote STEM in your local schools.

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Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct.

Astronomy is a magazine about the science and hobby of Astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

Astronomy was founded in 1973 by Stephen A. Walther, a graduate of The University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at The University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However, he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

From The Pennsylvania State University Via “EarthSky” : “Alien technology might signal extraterrestrial life”

From The Pennsylvania State University

Via

“EarthSky”

11.3.22
Macy Huston
Jason Wright

Advanced civilizations might be expected to produce “technology pollution” in the form of chemicals, light and heat. This technology should be detectable across the vast distances of space, astronomers say. Image via Jay Freidlander/NASA.

“If an alien were to look at Earth, our human technology – from cell towers to fluorescent light bulbs – could be a beacon signifying the presence of life.

We are two astronomers who work on the search for extraterrestrial intelligence, or SETI. In our research, we try to characterize and detect signs of technology – or technosignatures – originating from beyond Earth. Scanning the sky for a TV broadcast of some extraterrestrial Olympics may sound straightforward. But searching for signs of distant, advanced civilizations is a much more nuanced and difficult task than it might seem.

Saying ‘hello’ with technology like radios and lasers

A laser – like the one seen here – or beam of radio waves pointed intentionally at Earth would be a strong sign of extraterrestrial life. Image via G. Hüdepohl/ The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europäische Südsternwarte](EU)(CL)

The modern scientific search for extraterrestrial intelligence began in 1959 when astronomers Giuseppe Cocconi and Philip Morrison showed that radio telescopes at interstellar distances could detect radio transmissions from Earth. The same year, Frank Drake launched the first SETI search, Project Ozma, by pointing a large radio telescope at two nearby sun-like stars.

Howard E. Tatel Radio Telescope (85-1) at Green Bank site of the National Radio Astronomy Observatory (NRAO)

Frank Drake with his Drake Equation. Credit Frank Drake.

He was checking to see if he could detect any radio signals coming from them. Following the invention of the laser in 1960, astronomers detected visible light from distant planets.

These were the first foundational attempts to detect radio or laser signals.

Ohio State Big Ear Radio Telescope, Construction of the Big Ear began in 1956 and was completed in 1961, and it was finally turned on for the first time in 1963, disassembled in 1998 having operated for over 30 years.

“Wow!” signal from Ohio State Big Ear Radio Telescope Aug. 15, 1977.

They were looking for alien technology or powerful signals that another civilization intentionally sent to the solar system, meaning for them to be found.

Given the technological limitations of the 1960s, astronomers did not give serious thought to searching for broadcast signals – like television and radio broadcasts on Earth – that would leak into space. But a beam of a radio signal, with all its power focused toward Earth, could be detectable from much farther away. Just picture the difference between a laser and a weak light bulb.

SETI looks for radio and laser signals

The search for intentional radio and laser signals is still one of the most popular SETI strategies today. However, this approach assumes that extraterrestrial civilizations want to communicate with other technologically advanced life. Humans very rarely send targeted signals into space. And some scholars argue that intelligent species may purposefully avoid broadcasting their locations. The SETI Paradox is the search for signals that no one may be sending.

This artist’s impression shows the Square Kilometer Array, a telescope array under construction in both Australia and Africa. This array will be sensitive enough to detect the equivalent of radio broadcasts from distant planets. Image via SPDO/ TDP/ DRAO/ Swinburne Astronomy Productions.

Leaking radio waves

Humans don’t transmit many intentional signals out to the cosmos. But many technologies people use today produce a lot of radio transmissions that leak into space. Some of these signals would be detectable if they came from a nearby star.

The worldwide network of television towers constantly emits signals in many directions that leak into space. And they can accumulate into a detectable [Science (below)], though relatively faint, radio signal. Research is ongoing as to whether current emissions from cell towers in the radio frequency on Earth would be detectable using today’s telescopes. But the upcoming Square Kilometer Array radio telescope will be able to detect even fainter radio signals.

SKA-Square Kilometer Array

SKA ASKAP Pathfinder Radio Telescope at the Murchison Radio-astronomy Observatory (MRO), on the traditional lands of the Wajarri peoples.

SKA Square Kilometre Array low frequency at Murchison Widefield Array, Boolardy station in outback Western Australia on the traditional lands of the Wajarri peoples

SKA Murchison Widefield Array (AU), Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO), on the traditional lands of the Wajarri peoples.

SKA SARAO Meerkat Telescope (SA), 90 km outside the small Northern Cape town of Carnarvon, SA.

It will have 50 times the sensitivity of current radio telescope arrays.

Not all human-made signals are so unfocused, though. Astronomers and space agencies use beams of radio waves to communicate with satellites and spacecraft in the solar system. Some researchers also use radio waves for radar to study asteroids. These radio signals are more focused and pointed out into space. Any extraterrestrial civilization in the line of sight of these beams could likely detect these unambiguously artificial signals.

Finding megastructures

Aside from finding an actual alien spacecraft, radio waves are the most common technosignatures featured in sci-fi movies and books. But they are not the only signals that could be out there.

In 1960, astronomer Freeman Dyson theorized that, since stars are by far the most powerful energy source in any planetary system, a technologically advanced civilization might collect a significant portion of the star’s light as energy with what would essentially be a massive solar panel. Many astronomers call these megastructures, and there are a few ways to detect them.

After using the energy in the captured light, the technology of an advanced society would re-emit some of the energy as heat. Astronomers have shown that this heat could be detectable as extra infrared radiation coming from a star system.

Another possible way to find a megastructure would be to measure its dimming effect on a star. Specifically, large artificial satellites orbiting a star would periodically block some of its light. This would appear as dips in the star’s apparent brightness over time. Astronomers could detect this effect similarly to how scientists discover distant planets today.

A whole lot of technology pollution

Another technosignature that astronomers have thought about is pollution.

On Earth, chemical pollutants – like nitrogen dioxide and chlorofluorocarbons – are almost exclusively the product of human industry. It is possible to detect these molecules in the atmospheres of exoplanets with the same method the James Webb Space Telescope is using to search distant planets for signs of biology. If astronomers find a planet with an atmosphere filled with chemicals only produced by technology, it may be a sign of life.

Finally, scientists could also detect artificial light or heat from cities and industry with large optical and infrared telescopes. They could also detect a large number of satellites orbiting a planet. But a civilization would need to produce far more heat, light and satellites than Earth does to be detectable across the vastness of space using technology humans currently possess.

Which technology signal is best?

No astronomer has ever found a confirmed technosignature, so it’s hard to say what will be the first sign of alien civilizations. While many astronomers have thought a lot about what might make for a good signal, ultimately, nobody knows what extraterrestrial technology might look like and what signals are out there in the universe.

Some astronomers support a generalized SETI approach which searches for anything in space that current scientific knowledge cannot naturally explain. Some, like us, continue to search for both intentional and unintentional technosignatures. The bottom line is that there are many avenues for detecting distant life. Since no one knows what approach is likely to succeed first, there is still a lot of exciting work left to do.”

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Breakthrough Listen Project

UC Observatories Lick Automated Planet Finder fully robotic 2.4-meter optical telescope at Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California

Green Bank Radio Telescope, West Virginia, now the center piece of the Green Bank Observatory, being cut loose by the National Science Foundation, supported by Breakthrough Listen Project, West Virginia University, and operated by the nonprofit Associated Universities, Inc.

CSIRO-Commonwealth Scientific and Industrial Research Organisation (AU) Parkes Observatory [ Murriyang, the traditional Indigenous name] , located 20 kilometres north of the town of Parkes, New South Wales, Australia, 414.80m above sea level.

SKA SARAO Meerkat telescope(SA) 90 km outside the small Northern Cape town of Carnarvon, SA.

Newly added

University of Arizona Veritas Four Čerenkov telescopes A novel gamma ray telescope under construction at the CfA Fred Lawrence Whipple Observatory, Mount Hopkins, Arizona, altitude 2,606 m 8,550 ft. A large project known as the Čerenkov Telescope Array, composed of hundreds of similar telescopes to be situated at Roque de los Muchachos Observatory [Instituto de Astrofísica de Canarias ](ES) in the Canary Islands and Chile at European Southern Observatory Cerro Paranal(EU) site. The telescope on Mount Hopkins will be fitted with a prototype high-speed camera, assembled at the University of Wisconsin–Madison and capable of taking pictures at a billion frames per second. Credit: Vladimir Vassiliev. ___________________________________________________________________

Science paper:
Science 1978

See the full article here .

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Please help promote STEM in your local schools.

Stem Education Coalition

The The Pennsylvania State University is a public state-related land-grant research university with campuses and facilities throughout Pennsylvania. Founded in 1855 as the Farmers’ High School of Pennsylvania, Penn State became the state’s only land-grant university in 1863. Today, Penn State is a major research university which conducts teaching, research, and public service. Its instructional mission includes undergraduate, graduate, professional and continuing education offered through resident instruction and online delivery. In addition to its land-grant designation, it also participates in the sea-grant, space-grant, and sun-grant research consortia; it is one of only four such universities (along with Cornell University, Oregon State University, and University of Hawaiʻi at Mānoa). Its University Park campus, which is the largest and serves as the administrative hub, lies within the Borough of State College and College Township. It has two law schools: Penn State Law, on the school’s University Park campus, and Dickinson Law, in Carlisle. The College of Medicine is in Hershey. Penn State is one university that is geographically distributed throughout Pennsylvania. There are 19 commonwealth campuses and 5 special mission campuses located across the state. The University Park campus has been labeled one of the “Public Ivies,” a publicly funded university considered as providing a quality of education comparable to those of the Ivy League.
The Pennsylvania State University is a member of The Association of American Universities an organization of American research universities devoted to maintaining a strong system of academic research and education.

Annual enrollment at the University Park campus totals more than 46,800 graduate and undergraduate students, making it one of the largest universities in the United States. It has the world’s largest dues-paying alumni association. The university offers more than 160 majors among all its campuses.

Annually, the university hosts the Penn State IFC/Panhellenic Dance Marathon (THON), which is the world’s largest student-run philanthropy. This event is held at the Bryce Jordan Center on the University Park campus. The university’s athletics teams compete in Division I of the NCAA and are collectively known as the Penn State Nittany Lions, competing in the Big Ten Conference for most sports. Penn State students, alumni, faculty and coaches have received a total of 54 Olympic medals.

Early years

The school was sponsored by the Pennsylvania State Agricultural Society and founded as a degree-granting institution on February 22, 1855, by Pennsylvania’s state legislature as the Farmers’ High School of Pennsylvania. The use of “college” or “university” was avoided because of local prejudice against such institutions as being impractical in their courses of study. Centre County, Pennsylvania, became the home of the new school when James Irvin of Bellefonte, Pennsylvania, donated 200 acres (0.8 km2) of land – the first of 10,101 acres (41 km^2) the school would eventually acquire. In 1862, the school’s name was changed to the Agricultural College of Pennsylvania, and with the passage of the Morrill Land-Grant Acts, Pennsylvania selected the school in 1863 to be the state’s sole land-grant college. The school’s name changed to the Pennsylvania State College in 1874; enrollment fell to 64 undergraduates the following year as the school tried to balance purely agricultural studies with a more classic education.

George W. Atherton became president of the school in 1882, and broadened the curriculum. Shortly after he introduced engineering studies, Penn State became one of the ten largest engineering schools in the nation. Atherton also expanded the liberal arts and agriculture programs, for which the school began receiving regular appropriations from the state in 1887. A major road in State College has been named in Atherton’s honor. Additionally, Penn State’s Atherton Hall, a well-furnished and centrally located residence hall, is named not after George Atherton himself, but after his wife, Frances Washburn Atherton. His grave is in front of Schwab Auditorium near Old Main, marked by an engraved marble block in front of his statue.

Early 20th century

In the years that followed, Penn State grew significantly, becoming the state’s largest grantor of baccalaureate degrees and reaching an enrollment of 5,000 in 1936. Around that time, a system of commonwealth campuses was started by President Ralph Dorn Hetzel to provide an alternative for Depression-era students who were economically unable to leave home to attend college.

In 1953, President Milton S. Eisenhower, brother of then-U.S. President Dwight D. Eisenhower, sought and won permission to elevate the school to university status as The Pennsylvania State University. Under his successor Eric A. Walker (1956–1970), the university acquired hundreds of acres of surrounding land, and enrollment nearly tripled. In addition, in 1967, the Penn State Milton S. Hershey Medical Center, a college of medicine and hospital, was established in Hershey with a $50 million gift from the Hershey Trust Company.

Modern era

In the 1970s, the university became a state-related institution. As such, it now belongs to the Commonwealth System of Higher Education. In 1975, the lyrics in Penn State’s alma mater song were revised to be gender-neutral in honor of International Women’s Year; the revised lyrics were taken from the posthumously-published autobiography of the writer of the original lyrics, Fred Lewis Pattee, and Professor Patricia Farrell acted as a spokesperson for those who wanted the change.

In 1989, the Pennsylvania College of Technology in Williamsport joined ranks with the university, and in 2000, so did the Dickinson School of Law. The university is now the largest in Pennsylvania. To offset the lack of funding due to the limited growth in state appropriations to Penn State, the university has concentrated its efforts on philanthropy.

Research

Penn State is classified among “R1: Doctoral Universities – Very high research activity”. Over 10,000 students are enrolled in the university’s graduate school (including the law and medical schools), and over 70,000 degrees have been awarded since the school was founded in 1922.

Penn State’s research and development expenditure has been on the rise in recent years. For fiscal year 2013, according to institutional rankings of total research expenditures for science and engineering released by the National Science Foundation , Penn State stood second in the nation, behind only Johns Hopkins University and tied with the Massachusetts Institute of Technology , in the number of fields in which it is ranked in the top ten. Overall, Penn State ranked 17th nationally in total research expenditures across the board. In 12 individual fields, however, the university achieved rankings in the top ten nationally. The fields and sub-fields in which Penn State ranked in the top ten are materials (1st), psychology (2nd), mechanical engineering (3rd), sociology (3rd), electrical engineering (4th), total engineering (5th), aerospace engineering (8th), computer science (8th), agricultural sciences (8th), civil engineering (9th), atmospheric sciences (9th), and earth sciences (9th). Moreover, in eleven of these fields, the university has repeated top-ten status every year since at least 2008. For fiscal year 2011, the National Science Foundation reported that Penn State had spent $794.846 million on R&D and ranked 15th among U.S. universities and colleges in R&D spending.

For the 2008–2009 fiscal year, Penn State was ranked ninth among U.S. universities by the National Science Foundation, with $753 million in research and development spending for science and engineering. During the 2015–2016 fiscal year, Penn State received $836 million in research expenditures.

The Applied Research Lab (ARL), located near the University Park campus, has been a research partner with the Department of Defense since 1945 and conducts research primarily in support of the United States Navy. It is the largest component of Penn State’s research efforts statewide, with over 1,000 researchers and other staff members.

The Materials Research Institute was created to coordinate the highly diverse and growing materials activities across Penn State’s University Park campus. With more than 200 faculty in 15 departments, 4 colleges, and 2 Department of Defense research laboratories, MRI was designed to break down the academic walls that traditionally divide disciplines and enable faculty to collaborate across departmental and even college boundaries. MRI has become a model for this interdisciplinary approach to research, both within and outside the university. Dr. Richard E. Tressler was an international leader in the development of high-temperature materials. He pioneered high-temperature fiber testing and use, advanced instrumentation and test methodologies for thermostructural materials, and design and performance verification of ceramics and composites in high-temperature aerospace, industrial, and energy applications. He was founding director of the Center for Advanced Materials (CAM), which supported many faculty and students from the College of Earth and Mineral Science, the Eberly College of Science, the College of Engineering, the Materials Research Laboratory and the Applied Research Laboratories at Penn State on high-temperature materials. His vision for Interdisciplinary research played a key role in creating the Materials Research Institute, and the establishment of Penn State as an acknowledged leader among major universities in materials education and research.

The university was one of the founding members of the Worldwide Universities Network (WUN), a partnership that includes 17 research-led universities in the United States, Asia, and Europe. The network provides funding, facilitates collaboration between universities, and coordinates exchanges of faculty members and graduate students among institutions. Former Penn State president Graham Spanier is a former vice-chair of the WUN.

The Pennsylvania State University Libraries were ranked 14th among research libraries in North America in the 2003–2004 survey released by The Chronicle of Higher Education. The university’s library system began with a 1,500-book library in Old Main. In 2009, its holdings had grown to 5.2 million volumes, in addition to 500,000 maps, five million microforms, and 180,000 films and videos.

The university’s College of Information Sciences and Technology is the home of CiteSeerX, an open-access repository and search engine for scholarly publications. The university is also the host to the Radiation Science & Engineering Center, which houses the oldest operating university research reactor. Additionally, University Park houses the Graduate Program in Acoustics, the only freestanding acoustics program in the United States. The university also houses the Center for Medieval Studies, a program that was founded to research and study the European Middle Ages, and the Center for the Study of Higher Education (CSHE), one of the first centers established to research postsecondary education.

From The Arecibo Observatory Via “Live Science”: “Collapsed Arecibo telescope offers near-Earth asteroid warning from beyond the grave”

NAIC Arecibo Observatory operated by University of Central Florida, Yang Enterprises and Ana G. Méndez University [Universidad Ana G. Méndez, Recinto de Cupey] (PR) Altitude 497 m (1,631 ft), which has now collapsed.

An image of the Arecibo Observatory’s iconic radio telescope as seen between two serious cable failures that preceded the facility’s collapse in 2020. Image credit: University of Central Florida

From The Arecibo Observatory

Via

Live Science

10.30.22
Brandon Specktor

The famous Arecibo Observatory in Puerto Rico completely collapsed in 2020. Now, scientists going through its final observations offer a major new asteroid report.

Using data collected by Arecibo between December 2017 and December 2019, scientists have released the largest radar-based report on near-Earth asteroids ever published. The report, published Sept. 22 in The Planetary Science Journal below], includes detailed observations of 191 near-Earth asteroids, including nearly 70 that are deemed “potentially hazardous” — that is, large asteroids with orbits that bring them within 4.65 million miles (7.5 million kilometers) of Earth, or roughly 20 times the average distance between Earth and the moon.

The study’s ample amount of asteroid data is important for many reasons, including characterizing several potentially hazardous asteroids, supplying data on metal-rich and ice-rich near-Earth asteroids, and offering clues on the formation and evolution of the solar system. Image credit: Adobe Stock.

Fortunately, none of these newly described asteroids pose an immediate threat to Earth; according to NASA, our planet is safe from deadly asteroid impacts for at least the next 100 years. However, scientists still pay close attention to near-Earth objects like these in case their trajectories happen to shift by some fluke of nature — say, a bump from another asteroid — thereby putting them on a collision course with Earth.

The new report also flagged several asteroids deemed worthy of future study, including an oddball space object called 2017 YE5 — an ultra-rare “equal mass” binary asteroid, made of two nearly identical size rocks that are constantly orbiting one another. (Each of the rocks is estimated to measure between 2,600 and 2,950 feet, or 800 to 900 meters, in diameter). The asteroid’s high radar reflectivity may indicate an abundance of water ice beneath its surface, possibly making it a never-before-seen class of icy, equal mass, near-Earth asteroid, the researchers wrote.

A handful of the newly-imaged asteroids, including the rare “equal mass” binary asteroid 2017 YE5 (bottom left). (Image credit: Virkki et al/ Planetary Science Journal)

With this new “treasure trove” of data, scientists can better measure these asteroids’ shapes, sizes and spin periods, which are crucial metrics for assessing the potential risks that the asteroids may pose to our planet, lead study author Anne Virkki, a researcher with the Department of Physics at the University of Helsinki in Finland, said in a statement.

“The amount of valuable data collected is unique, and these results could not have been achieved with any other existing facility,” study co-author Flaviane Venditti, head of Arecibo’s Planetary Radar Science Group, added.

The Arecibo Observatory was constructed in Puerto Rico in 1963, becoming the world’s largest and most powerful radio telescope. Its iconic 1,000-foot-wide (305 m) telescope dish became world famous in the 1990s after it was featured in movies such as Contact (1997) and GoldenEye (1995). By then, the observatory was already known in the scientific community for beaming humanity’s first message to aliens into space in 1974.

More recently, Arecibo’s observations of asteroids played a direct role in planning NASA’s Double Asteroid Redirection Test (DART) mission, in which scientists crashed a spacecraft into the near-Earth asteroid Dimorphos and altered its orbital period by 32 minutes.

National Aeronautics Space Agency DART in space depiction.

Science paper:
The Planetary Science Journal
See the science paper for detailed material with images.

See the full article here .

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Please help promote STEM in your local schools.

Stem Education Coalition

The Arecibo Observatory was a radio telescope in the municipality of Arecibo, Puerto Rico. This observatory was operated by SRI International, USRA and UMET, under cooperative agreement with the National Science Foundation (NSF). The observatory is the sole facility of the National Astronomy and Ionosphere Center (NAIC), which refers to the observatory, and the staff that operates it. From its construction in the 1960s until 2011, the observatory was managed by Cornell University.

The observatory’s 1,000-foot (305-meter) radio telescope was the largest single-aperture telescope from its completion in 1963 until July 2016 when the Five hundred meter Aperture Spherical Telescope (FAST) in China was completed. It is used in three major areas of research: radio astronomy, atmospheric science, and radar astronomy. Scientists who want to use the observatory submit proposals that are evaluated by an independent scientific board.