From COSMOS: “How non-optical telescopes see the universe”

COSMOS Magazine

24 July 2017
Jake Port

The human eye can only see a tiny band of the electromagnetic spectrum. That tiny band is enough for most day-to-day things you might want to do on Earth, but stars and other celestial objects radiate energy at wavelengths from the shortest (high-energy, high-frequency gamma rays) to the longest (low-energy, low-frequency radio waves).

The electromagnetic spectrum is made up of radiation of all frequencies and wavelengths. Only a tiny range is visible to the human eye. NASA.

Beyond the visible spectrum

To see what’s happening in the distant reaches of the spectrum, astronomers use non-optical telescopes. There are several varieties, each specialised to catch radiation of particular wavelengths.

Non-optical telescopes utilise many of the techniques found in regular telescopes, but also employ a variety of techniques to convert invisible light into spectacular imagery. In all cases, a detector is used to capture the image rather than an eyepiece, with a computer then processing the data and constructing the final image.

There are also more exotic ways of looking at the universe that don’t use electromagnetic radiation at all, like neutrino telescopes and the cutting-edge gravitational wave telescopes, but they’re a separate subject of their own.

To start off, let’s go straight to the top with the highest-energy radiation, gamma rays.

Gamma ray telescopes

Gamma radiation is generally defined as radiation of wavelengths less than 10−11 m, or a hundredth of a nanometre.

Gamma-ray telescopes focus on the highest-energy phenomena in the universe, such as black holes and exploding stars. A high-energy gamma ray may contain a billion times as much energy as a photon of visible light, which can make them difficult to study.

Unlike photons of visible light, that can be redirected using mirrors and reflectors, gamma rays simply pass through most materials. This means that gamma-ray telescopes must use sophisticated techniques that track the movement of individual gamma rays to construct an image.

One technology that does this, in use in the Fermi Gamma-ray Space Telescope among other places, is called a pair production telescope.

NASA/Fermi Telescope

It uses a multi-layer sandwich of converter and detector materials. When a gamma ray enters the front of the detector it hits a converter layer, made of dense material such as lead, which causes the gamma-ray to produce an electron and a positron (known as a particle-antiparticle pair).

The electron and the positron then continue to traverse the telescope, passing through layers of detector material. These layers track the movement of each particle by recording slight bursts of electrical charge along the layer. This trail of bursts allows astronomers to reconstruct the energy and direction of the original gamma ray. Tracing back along that path points to the source of the ray out in space. This data can then be used to create an image.

The video below shows how this works in the space-based Fermi Large Area Telescope.

NASA/Fermi LAT

X-ray telescopes

X-rays are radiation with wavelengths between 10 nanometres and 0.01 nanometres. They are used every day to image broken bones and scan suitcases in airports and can also be used to image hot gases floating in space. Celestial gas clouds and remnants of the explosive deaths of large stars, known as supernovas, are the focus of X-ray telescopes.

Like gamma rays, X-rays are a high-energy form of radiation that can pass straight through most materials. To catch X-rays you need to use materials that are very dense.

X-ray telescopes often use highly reflective mirrors that are coated with dense metals such as gold, nickel or iridium. Unlike optical mirrors, which can bounce light in any direction, these mirrors can only slightly deflect the path of the X-ray. The mirror is orientated almost parallel to the direction of the incoming X-rays. The X-rays lightly graze the mirror before moving on, a little like a stone skipping on a pond. By using lots of mirrors, each changing the direction of the radiation by a small amount, enough X-rays can be collected at the detector to produce an image.

To maximise image quality the mirrors are loosely stacked, creating an internal structure resembling the layers of an onion.

Diagram showing how ‘grazing incidence’ mirrors are used in X-ray telescopes. NASA.

NASA/Chandra X-ray Telescope

ESA/XMM Newton X-ray telescope

NASA NuSTAR X-ray telescope

Ultraviolet telescopes

Ultraviolet light is radiation with wavelengths just too short to be visible to human eyes, between 400 nanometres and 0.01 nanometres. It has less energy than X-rays and gamma rays, and ultraviolet telescopes are more like optical ones.

Mirrors coated in materials that reflect UV radiation, such as silicon carbide, can be used to redirect and focus incoming light. The Hopkins Ultraviolet Telescope, which flew two short missions aboard the space shuttle in the 1990s, used a parabolic mirror coated with this material.

A schematic of the Hopkins Ultraviolet Telescope. NASA.

NASA Hopkins Ultraviolet Telescope which flew on the ISS

As redirected light reaches the focal point, a central point where all light beams converge, they are detected using a spectrogram. This specialised device can separate the UV light into individual wavelength bands in a way akin to splitting visible light into a rainbow.

Analysis of this spectrogram can indicate what the observation target is made of. This allows astronomers to analyse the composition of interstellar gas clouds, galactic centres and planets in our solar system. This can be particularly useful when looking for elements essential to carbon-based life such as oxygen and carbon.

Optical telescopes

Optical telescopes are used to view the visible spectrum: wavelengths roughly between 400 and 700 nanometres. See separate article here.

Keck Observatory, Maunakea, Hawaii, USA

ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain, sited on a volcanic peak 2,267 metres (7,438 ft) above sea level

Gemini/North telescope at Maunakea, Hawaii, USA

Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile

Infrared telescopes

Sitting just below visible light on the electromagnetic spectrum is infrared light, with wavelengths between 700 nanometres and 1 millimetre.

It’s used in night vision goggles, heaters and tracking devices as found in heat-seeking missiles. Any object or material that is hotter than absolute zero will emit some amount of infrared radiation, so the infrared band is a useful window to look at the universe through.

Much infrared radiation is absorbed by water vapour in the atmosphere, so infrared telescopes are usually at high altitudes in dry places or even in space, like the Spitzer Space Telescope.

Infrared telescopes are often very similar to optical ones. Mirrors and reflectors are used to direct the infrared light to a detector at the focal point. The detector registers the incoming radiation, which a computer then converts into a digital image.

NASA/Spitzer Infrared Telescope

Radio telescopes

At the far end of the electromagnetic spectrum we find the radio waves, with frequencies less than 1000 megahertz and wavelengths of a metre and more. Radio waves penetrate the atmosphere easily, unlike higher-frequency radiation, so ground-based observatories can catch them.

Radio telescopes feature three main components that each play an important role in capturing and processing incoming radio signals.

The first is the massive antenna or ‘dish’ that faces the sky. The Parkes radio telescope in New South Wales, Australia, for instance, has a dish with a diameter of 64 metres, while the Aperture Spherical Telescope in southwest China is has a whopping 500-metre diameter.

The great size allows for the collection of long wavelengths and very quiet signals. The dish is parabolic, directing radio waves collected over a large area to be focused to a receiver sitting in front of the dish. The larger the antenna, the weaker the radio source that can be detected, allowing larger telescopes to see more distant and faint objects billions of light years away.

The receiver works with an amplifier to boost the very weak radio signal to make it strong enough for measurement. Receivers today are so sensitive that they use powerful coolers to minimise thermal noise generated by the movement of atoms in the metal of the structure.

Finally, a recorder stores the radio signal for later processing and analysis.

Radio telescopes are used to observe a wide array of subjects, including energetic pulsar and quasar systems, galaxies, nebulae, and of course to listen out for potential alien signals.

CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia

GBO radio telescope, Green Bank, West Virginia, USA

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

From astrobites: “An unconventional solar fountain”

Astrobites

Jul 19, 2017
Amber Hornsby

Title: The association of a J-burst with a solar jet
Authors: D. E. Morosan et al.
First Author’s Institution: School of Physics, Trinity College Dublin, Ireland

Status: Submitted to A&A, open access

Figure 1: Charged particles from the Sun interacting with the Earth’s magnetosphere excite particles in the atmosphere, creating dazzling light shows – the Aurorae. This image was taken on the International Space Station (ISS). Credit: NASA.

Our local star, the Sun, is an active star. It regularly sends streams of highly energetic particles hurtling towards our home planet, causing dazzling auroral displays at the poles, and occasionally we notice emissions in the radio regime. Back in July 2013, an unusual and very bright burst of radio wave energy was observed by the Low Frequency Array (LOFAR) based in the Netherlands, with our Sun being the likely culprit.

ASTRON LOFAR Radio Antenna Bank

ASTRON LOFAR Map

Today’s bite will illustrate how J-bursts, an unconventional type of jet from the Sun, differ from the so-called type III bursts commonly observed. Also, we will describe their likely origin and the proposed mechanism to explain their odd characteristics.

Twist-it!

Figure 2: Twisting of magnetic fields from the rotation of the Sun stores energy in entangled field lines. When field lines reorganise themselves, they release bursts of energy. Credit: Addison Wesley.

Being made of plasma (hot, ionised gas) means the surface of the Sun experiences differential rotation – the material at located towards the equator travels faster than material located at the poles. This leads to magnetic field lines, pointing from pole to pole, to become twisted over time leading to very strong localised fields and is the cause of dark regions on the Sun known as sunspots. Generally field lines do not want to be tangled, therefore they re-arrange themselves, resulting in energetic solar events such as: solar flares, jets and Coronal Mass Ejections (CMEs). These events causes particles to be accelerated along field lines as they travel away from the source of activity.

A what-burst?

Solar flares and jets are commonly associated with X-ray emission and type III radio bursts, with the main difference being the resulting direction of the electron as it travels away from the Sun. Electrons accelerated by the re-configuring magnetic field can travel up through the corona, the aura around the Sun only visible during a solar eclipse, or down towards the layer located just above the surface (photosphere) – the chromosphere. Different layers of the Sun can be seen below in Figure 3.

igure 3: An artistic view dissecting the internal layers of the Sun. The regions of interest in today’s bite are the outer two layers – the chromosphere and the corona. Credit: NASA

It is the electrons accelerating towards the corona which result in type III bursts and are identified as rapidly varying bursts of radiation which last a few seconds. They are considered to be the radio signature associated with electrons travelling via the corona, into interplanetary space along magnetic field lines. Several typical type III radio bursts are visible as vertical bursts in the top panel of Figure 4. Generally type III bursts are the result of electrons escaping via the corona because they have access to open magnetic fields lines, but this is not always the case.

Figure 4: Multiple Type III radio bursts observed by LOFAR at frequencies in the range of 10 – 240 MHz. The top panel is a dynamical spectrum. It shows the strength of the signal of a certain frequency (vertical axis) as a function of time (horizontal axis). Figure 1 of paper (top two panels)

Today’s peculiar burst contained no radio waves below 30 MHz (top panel of Figure 4), therefore the authors coined this particular burst a J-burst. It was observed using the Low Frequency Array (LOFAR) based in the Netherlands. For more details about LOFAR, check out this awesome astrobite.

Where did it come from?

Already suspected to be solar in origin, scientists turned to an observatory which has been observing the Sun since 2011 – the Solar Dynamics Observatory (SDO). The SDO is able to produce one high resolution image of the Sun every second, making it the best space-based eye we currently have on our local star when compared to the STEREO and SOHO observatories.

NASA/STEREO spacecraft

ESA/NASA SOHO

A solar jet was observed by the SDO at a time and location coincident to the burst in question. Its evolution as a function of time is highlighted in Figure 5 by a white arrow. The jet glows in panel (b) but has faded by panel (d), lasting around 8 minutes in total.

Figure 5: Evolution of jet which caused J-burst as a function of time. It glows in panels (b) and (c), but is not visible in (a) and has faded by (d). Figure 4 of paper

Scientists continued their investigations by plotting their LOFAR observations at different frequencies on top images taken by the SDO. Observations were extended to higher frequencies of 150 and 228 MHz via the Nançay Radioheliograph (NRH) based in France. The evolving frequencies as a function of time tell an interesting story about the journey of some electrons.

Nancay Radioheliograph North arm (Meudon, Observatoire de Paris)

Figure 6: Radio contours taken from LOFAR observations overlaid on SDO images highlight how the frequency of radio waves observed evolves with time. Higher frequencies were taken from NRH data. Figure 2 of paper.

What is going on?

The J-burst appears at 11:06:24 UT over a wide range of frequencies in Figure 6(b), including two LOFAR sources at 72 and 78 MHz (white and yellow contours) are associated with the highlighted jet (pink contour). The 228 and 150 MHz sources in the bottom right of Figure 6 (a-d) appear to be unrelated to this J-burst as it lasts around 10s and does not drift in frequency like the J-burst does. The 150 MHz source (blue contour) visible in Figure 6(b) is a component of the J-burst, but it has faded by Figure 6(c). The white and yellow contours shift to the right from their original location in Figure 6(c) which suggests we are sampling an electron beam moving in a different direction.

The radio sources 72, 78, 55 and 50 and 39 MHz move southwards from their initial location and decrease in frequency. By Figure 6(d) only the lowest frequency radio sources remain. The appearance and behaviour of the sources suggests an initial electron beam was accelerated to produce the burst in Figure 6(b) but eventually the electrons reached a region where they stop producing radio emission i.e they were no longer travelling upwards through the corona and had become trapped in a closed magnetic field loop – this could explain this lack of observations below 30 MHz shown in Figure 4.

Conclusion

An unusual burst of radio energy observed at frequencies above 30 MHz, a J-burst was likely caused by electrons, which are accelerated by the reconfiguration of the Sun’s magnetic field, becoming trapped within a closed magnetic field loop whilst travelling upwards through the corona. Even with a vast number of investigations and models of solar jets associated with radio emission, alongside a well-known classification system, there are still unanswered questions about their exact mechanism and the path followed by accelerated electrons in the solar corona. Today’s paper has explored these themes and arrived at some interesting conclusions, but there is a still a lot of work to be done.

This discovery does highlight the usefulness of radio emission as a tool to study the Sun’s magnetic field as its affect on charged particles, but it also puts an emphasis on the need for an instrument with a broader range of frequencies to probe flaring events associated with particle accelerations. The authors required the use of a wide range of instruments in order to draw their conclusions – something which might not always be possible – therefore they highlight the European Solar Radio Array (ESRA) as a highly promising candidate mission for future funding.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

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.

NRAO VLA, Courtesy of Juan Carlos, Magical Universe

NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

The very large array or Karl V Jansky VLA is an observatory located on the plains of st. Augustine, between the towns of Magdalena and Datil, about 80 km west of Socorro, New Mexico, United States. The VLA is located at an altitude of 6970 ft [2.124] meters above sea level. It is part of the National Radio Observatory Observatory (NSF/NRAO), operated under cooperative agreement by Associated Universities, Inc. The Observatory consists of 27 independent antennas, each of which has a disc diameter of 25 metres and a weight of 209 tonnes. The antennae are aligned along three arms in the form of a Y-shaped array, and each arm is 21 miles. Using the railway tracks that follow each of these arms and a specially designed locomotive, the antennae can be physically relocated to a number of prepared positions, allowing with a maximum base of 36 km. Essentially the alignment acts as the only radio telescope with that diameter. The Highest Angular resolution that can be reached is about 0.05 seconds of arc.

There are four commonly used settings, called a (the major) to d (the minor), the minor configuration is when all the disks are less than 600 m from the central point. The Observatory normally passes through all possible configurations (including some hybrids) every 16 months, in other words, once the incredible effort needed to move two dozen highly sensitive scientific instruments of 209 tons has been carried out, Antennas are not moved again for a period of about three to four months. The also serves as a control centre for the Very Long Baseline Array (VLBA).

NRAO/VLBA

NRAO/VLBA

From ALMA: “Heart of an Exploded Star Observed in 3-D”

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres
ALMA

10 July, 2017

Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726
nicolas.lira@alma.cl

Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Phone: +1 434 296 0314
Cell phone: +1 202 236 6324
cblue@nrao.edu

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo – Japan
Phone: +81 422 34 3630
hiramatsu.masaaki@nao.ac.jp

Richard Hook
Public Information Officer, ESO
Garching bei München, Germany
Phone: +49 89 3200 6655
Cell phone: +49 151 1537 3591
rhook@eso.org

This artist’s illustration of Supernova 1987A reveals the cold, inner regions of the exploded star’s remnants (red) where tremendous amounts of dust were detected and imaged by ALMA. This inner region is contrasted with the outer shell (blue), where the energy from the supernova is colliding (green) with the envelope of gas ejected from the star prior to its powerful detonation. Credit: A. Angelich; NRAO/AUI/NSF

Deep inside the remains of an exploded star lies a twisted knot of newly minted molecules and dust forged in the cooling aftermath of a supernova first detected in 1987. Using ALMA, astronomers mapped the location of these new molecules to create a high-resolution 3-D image of this “dust factory,” providing important insights into the relationship between a young supernova remnant and its home galaxy.

Supernovas — the violent ending of the brief but brilliant lives of massive stars — are among the universe’s most cataclysmic events. Though supernovas mark the death of stars, they also trigger the birth of new elements and the formation of molecules that fill the universe.

In February of 1987, astronomers witnessed one of these events unfold inside the Large Magellanic Cloud, a tiny dwarf galaxy in the suburbs of the Milky Way approximately 163,000 light-years from Earth.

Over the next 30 years, observations of the remnant of that explosion revealed never-before-seen details about the death of stars and how atoms created in those stars — like carbon, oxygen, and nitrogen — spill out into space and combine to form new molecules and dust. These microscopic particles may eventually find their way into future generations of stars and planets.

Remnant of Supernova 1987A as seen by ALMA. Purple area indicates emission from SiO molecules. Yellow area is emission from CO molecules. The blue ring is actual Hubble data (H-alpha) that has been artificially expanded into 3-D. Credit: ALMA (ESO/NAOJ/NRAO); R. Indebetouw

NASA/ESA Hubble Telescope

Recently, astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) to probe the heart of this supernova, named SN 1987A. ALMA’s ability to see remarkably fine details allowed the researchers to produce a detailed 3-D rendering of newly formed molecules inside the supernova remnant. These results are published in the Astrophysical Journal Letters.

The researchers also discovered a variety of previously undetected molecules in the remnant. Those results will appear in the Monthly Notices of the Royal Astronomical Society.

“When this supernova exploded now more than 30 years ago, astronomers knew much less about the way these events reshape interstellar space and how the hot, glowing debris from an exploded star eventually cools and produces new molecules,” said Rémy Indebetouw, an astronomer at the University of Virginia and the National Radio Astronomy Observatory (NRAO) in Charlottesville. “Thanks to ALMA we can finally see cold ‘star dust’ as it forms, revealing important insights into the original star itself and the way supernovas create the basic building blocks of planets.”

Supernovas – Star Death to Dust Birth

Prior to ongoing investigations of SN 1987A, there was only so much astronomers could determine about these explosive cosmic events.

It was well understood that massive stars, those approximately 10 times the mass of our sun, ended their lives in spectacular fashion. When these stars run out of fuel, there is no longer enough heat and energy to fight back against the force of gravity. The outer reaches of the star, once held up by the power of fusion, then come crashing down on the core with tremendous force. The rebound of this collapse triggers an explosion that blasts material into space.

As the endpoint of massive stars, scientists have learned that supernovas have far-reaching effects on galaxies across the universe. To get a better understanding of these effects, Indebetouw helps break down the impact of these star-shattering events. “The reason some galaxies have the appearance that they do today is in large part because of the supernovas that have occurred in them,” he said. “Though less than 10 percent of stars in galaxies , the ones that explode as supernovas dominate the evolution of galaxies.”

Throughout the observable universe, supernovas are quite common, but since they appear – on average – about once every 50 years in a galaxy the size of the Milky Way, astronomers have precious few opportunities to study one from its first detonation to the point where it cools enough to form new molecules. Though SN 1987A is not technically in our home galaxy, it is still close enough for ALMA and other telescopes to study in fine detail.

Astronomers combined observations from three different observatories to produce this colorful, multiwavelength image of the intricate remains of Supernova 1987A.The red color shows newly formed dust in the center of the supernova remnant, taken at submillimeter wavelengths by the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile. The green and blue hues reveal where the expanding shock wave from the exploded star is colliding with a ring of material around the supernova. The green represents the glow of visible light, captured by NASA’s Hubble Space Telescope. The blue color reveals the hottest gas and is based on data from NASA’s Chandra X-ray Observatory.The ring was initially made to glow by the flash of light from the original explosion. Over subsequent years the ring material has brightened considerably as the explosion’s shock wave slams into it. Supernova 1987A resides 163,000 light-years away in the Large Magellanic Cloud, where a firestorm of star birth is taking place. Credit: NASA/ESA, ALMA (ESO/NAOJ/NRAO)

NASA/Chandra Telescope

Capturing 3-D Image of SN1987A with ALMA

For decades, radio, optical, and even X-ray observatories have studied of SN 1987 A, but obscuring dust in the outer regions of the remnant made it difficult to analyze the supernova’s innermost core. ALMA’s ability to observe at millimeter wavelengths – a region of the electromagnetic spectrum between infrared and radio light – made it possible to see through the intervening dust and gas and study the abundance and location of newly formed molecules – especially silicon monoxide (SiO) and carbon monoxide (CO), which shine brightly at the short submillimeter wavelengths that ALMA can perceive.

In the new ALMA image and animation, emission from SiO (colored purple) and CO (colored yellow) is located in discrete clumps within the core of SN 1987A. Indebetouw said that scientists previously predicted how and where these molecules would appear, but without ALMA they were unable to capture images with high enough resolution to confirm the structure inside the remnant and test those models.

Aside from obtaining the first 3-D image of SN 1987A, the ALMA data also reveal compelling details about how the physical conditions have changed and continues to change over time. These observations also provide insights into the physical instabilities in a supernova.

New Insights from SN 1987A

Earlier observations with ALMA verified that SN 1987A produced a massive amount of dust. The new observations provide more details on how the supernova made the dust as well as the type of molecules found in it.

“One of our goals was to observe SN 1987A in a blind search for other molecules,” said Indebetouw. “We expected to find carbon monoxide and silicon monoxide, since we had previously detected these molecules.” The astronomers, however, were excited to find the previously undetected molecules HCO+ and sulfur monoxide (SO).

“These molecules had never been detected in a young supernova remnant before,” noted Indebetouw. “HCO+ is especially interesting because its formation requires particularly vigorous mixing during the explosion.”

The current observations allow the astronomers to estimate that about 1 in 1000 silicon atoms from the exploded star are now found in SiO molecules; astronomers think that the majority of the silicon is currently in dust grains. Even the small amount of SiO that is present is 100 times greater than predicted by dust formation models. These new observations will aid astronomers in refining these models.

These observations also find that 10 percent or more of the carbon in the exploded star is currently in a CO molecule. Only a few out of every million carbon atoms are in a HCO+ molecule.

New Questions and Future Research

Even though the new ALMA observations shed important light on SN 1987A, there are still several questions that remain. Exactly how abundant are the molecules of HCO+ and SO? Are there other molecules that have yet to be detected? How will the 3-D structure of SN 1987A continue to change over time?

Future ALMA observations at different wavelengths may also shed light on what sort of compact object — a pulsar or neutron star — resides at the center of this object. Such an object has been predicted but so far not detected inside SN 1987A.

There are many animations in the article which are [foolishly] in Vimeo, which I cannot reproduce. See the full article for these animations.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

From NRAO: “Star’s Birth May Have Triggered Another Star Birth, Astronomers Say”

National Radio Astronomy Observatory

June 20, 2017
Dave Finley, Public Information Officer
(575) 835-7302
dfinley@nrao.edu

Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have found new evidence suggesting that a jet of fast-moving material ejected from one young star may have triggered the formation of another, younger protostar.

Protostar FIR 3 (HOPS 370) with outflow that may have triggered the formation of younger protostar FIR 4 (HOPS 108, location marked with red dot), in the Orion star-forming region. (au = astronomical unit, the distance from the Earth to the Sun, about 93 million miles.)
Credit: Osorio et al., NRAO/AUI/NSF.

Protostar FIR 3 (HOPS 370) with outflow that may have triggered the formation of younger protostar FIR 4 (HOPS 108), in the Orion star-forming region. Pullouts are individual VLA images of each protostar. (au = astronomical unit, the distance from the Earth to the Sun, about 93 million miles.)
Credit: Osorio et al., NRAO/AUI/NSF.

“The orientation of the jet, the speed of its material, and the distance all are right for this scenario,” said Mayra Osorio, of the Astrophysical Institute of Andalucia (IAA-CSIC) in Spain. Osorio is the lead author of a paper reporting the findings in the Astrophysical Journal.

The scientists studied a giant cloud of gas some 1,400 light-years from Earth in the constellation Orion, where numerous new stars are being formed. The region has been studied before, but Osorio and her colleagues carried out a series of VLA observations at different radio frequencies that revealed new details.

Images of the pair show that the younger protostar, called HOPS (Herschel Orion Protostar Survey) 108, lies in the path of the outflow from the older, called HOPS 370. This alignment led Yoshito Shimajiri and collaborators to suggest in 2008 that the shock of the fast-moving material hitting a clump of gas had triggered the clump’s collapse into a protostar.

“We found knots of material within this outflow and were able to measure their speeds,” said Ana K. Diaz-Rodriguez also of IAA-CSIC.

The new measurements gave important support to the idea that the older star’s outflow had triggered the younger’s star’s formation process.

The scientists suggest that the jet from HOPS 370 (also known as FIR 3) began to hit the clump of gas about 100,000 years ago, starting the process of collapse that eventually led to the formation of HOPS 108 (also known as FIR 4). Four other young stars in the region also could be the result of similar interactions, but the researchers found evidence for shocks only in the case of HOPS 108.

While the evidence for this triggering scenario is strong, one fact appears to contradict it. The younger star seems to be moving rapidly in a way that indicates it should have been formed elsewhere, apart from the region impacted by the older star’s outflow.

“This motion, however, might be an illusion possibly created by an outflow from the newer star itself,” explained Osorio. “We want to continue to observe it over a period of time to resolve this question,” she added.

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

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

ESO/NRAO/NAOJ 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).

NRAO VLBA

NRAO VLBA

*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.

And the future Expanded Very Large Array (EVLA).

From NRAO: “VLA Gives New Insight Into Galaxy Cluster’s Spectacular ‘Mini-Halo'”

National Radio Astronomy Observatory

June 13, 2017
Dave Finley, Public Information Officer
(575) 835-7302
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Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have discovered new details that are helping them decipher the mystery of how giant radio-emitting structures are formed at the center of a cluster of galaxies.

The scientists studied a cluster of thousands of galaxies more than 250 million light-years from Earth, named the Perseus Cluster after the constellation in which it appears. Embedded within the center, the Perseus Cluster hosts a pool of superfast particles that emit radio waves, creating a radio structure known as a “mini-halo.” Mini-haloes have been found in about 30 galaxy clusters, but the halo in the Perseus Cluster is the largest known, about 1.3 million light-years in diameter, or 10 times the size of our Milky Way Galaxy.

The sizes of the mini-haloes have presented a puzzle to astronomers. As the particles travel away from the cluster’s center, they should slow down and stop emitting radio waves long before they reach the distances observed, according to theory.

“At large distances from the central galaxy, we don’t expect to be able to see these haloes,” said Marie-Lou Gendron-Marsolais, of the University of Montreal. “However, we do see them and we want to know why,” she added.

The astronomers took advantage of the upgraded capabilities of the VLA to make new images of the Perseus Cluster that were both more sensitive to fainter radio emissions and provided higher resolution than previous radio observations.

“The new VLA images provided an unprecedented view of the mini-halo by revealing a multitude of new structures within it,” said Julie Hlavacek-Larrondo, also of the University of Montreal. “These structures tell us that the origin of the radio emission is not as simple as we thought,” she said.

The new details indicate that the halo’s radio emission is caused by complex mechanisms that vary throughout the cluster. As theorized before, some radio emission is caused by particles being reaccelerated when small groups of galaxies collide with the cluster and give the particles a gravitational shove. In addition, however, the scientists now think that the radio emission is also caused by the powerful jets of particles generated by the supermassive black hole at the core of the central galaxy that give an extra “kick” of energy to the particles.

“This would help explain the rich variety of complex structures that we see,” Gendron-Marsolais said.

“The high-quality images that the upgraded VLA can produce will be key to helping us gain new insights into these mini-haloes in our quest to understand their origin,” Hlavacek-Larrondo said.

The VLA, built during the 1970s, was equipped with all-new electronics to bring it up to the technological state of the art by a decade-long project completed in 2012. The images of the Perseus Cluster were made using a new low frequency receiver system funded by the Naval Research Laboratory (NRL) and built through collaboration between NRL and the National Radio Astronomy Observatory.

Gendron-Marsolais and Hlavacek-Larrondo, along with an international team of researchers, are reporting their findings in the Monthly Notices of the Royal Astronomical Society.

See the full article here .

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NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

ESO/NRAO/NAOJ 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).

NRAO VLBA

NRAO VLBA

*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.

And the future Expanded Very Large Array (EVLA).

From SKA: “Ghana and South Africa celebrate first light of SKA-linked African network of radio telescopes”

SKA Square Kilometer Array

SKA

5 July 2017
No writer credit found

The Ministries of Ghana and South Africa announced the combination of ‘first light’ science observations which confirm the successful conversion of a Ghanaian communications antenna from a redundant telecoms instrument into a functioning Very Long Baseline Interferometry (VLBI) radio telescope.

SKA The 32m Kutunse antenna at the Ghana Radio Astronomy Observatory.

Ghana is the first partner country of the African Very Large Baseline Interferometer (VLBI) Network (AVN) to complete the conversion of a communications antenna into a functioning radio telescope. The 32-metre converted telecommunications antenna at the Ghana Intelsat Satellite Earth Station at Kutunse will be integrated into the African VLBI Network (AVN) in preparation for the second phase construction of the Square Kilometre Array (SKA) across the African continent.

Nine African partner countries are members of the AVN, including Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia, South Africa, and Zambia.

As an SKA Africa partner country, Ghana welcomed and collaborated with the SKA South Africa (SKA SA)/HartRAO (Hartebeesthoek Radio Astronomical Observatory) group to harness the radio astronomy potential of the redundant satellite communication antenna at Kutunse.

Hartebeesthoek Radio Astronomy Observatory, located west of Johannesburg South Africa

A team of scientists and engineers from SKA SA/HartRAO and the Ghana Space Science and Technology Institute (GSSTI) which is under the Ghanaian Ministry of Environment, Science, Technology and Innovation (MESTI), has been working since 2011 on the astronomy instrument upgrade to make it radio-astronomy ready.

“A vital part of the effort towards building SKA on the African Continent over the next decade is to develop the skills, regulations and institutional capacity needed in SKA partner countries to optimise African participation in the SKA,” says the South African Minister of Science and Technology, Mrs Naledi Pandor. The AVN programme is aimed at transferring skills and knowledge in African partner countries to build, maintain, operate and use radio telescopes. Minister Pandor continued by saying: “It will bring new science opportunities to Africa on a relatively short time scale and develop radio astronomy science communities in SKA partner countries.”

See the full article here .

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SKA Square Kilometer Array

SKA ASKAP Pathefinder Telescope

SKA Meerkat telescope, 90 km outside the small Northern Cape town of Carnarvon, SA

SKA Meerkat Telescope

Murchison Widefield Array,SKA Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO)

SKA Murchison Wide Field Array

About SKA

The Square Kilometre Array will be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. Construction of phase one of the SKA is scheduled to start in 2016. The SKA Organisation, with its headquarters at Jodrell Bank Observatory, near Manchester, UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, led by SKA Organisation. The SKA will conduct transformational science to improve our understanding of the Universe and the laws of fundamental physics, monitoring the sky in unprecedented detail and mapping it hundreds of times faster than any current facility.

Already supported by 10 member countries – Australia, Canada, China, India, Italy, New Zealand, South Africa, Sweden, The Netherlands and the United Kingdom – SKA Organisation has brought together some of the world’s finest scientists, engineers and policy makers and more than 100 companies and research institutions across 20 countries in the design and development of the telescope. Construction of the SKA is set to start in 2018, with early science observations in 2020.

From ALMA: “ALMA Reveals Turbulent Birth of Twin Baby Stars”

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres
ALMA

Nicolás Lira T.
Press Coordinator
Joint ALMA Observatory
Santiago, Chile
Tel: +56 2 24 67 65 19
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Email: nicolas.lira@alma.cl

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
Tokyo, Japan

Tel: +81 422 34 3630

E-mail: hiramatsu.masaaki@nao.ac.jp

Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory
Charlottesville, Virginia, USA
Tel: +1 434 296 0314
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E-mail: cblue@nrao.edu

Richard Hook
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Garching bei München, Germany

Tel: +49 89 3200 6655

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Email: rhook@eso.org

Artist’s impression of the baby twin system IRAS 04191+1523. Credit: ALMA (ESO/NAOJ/NRAO)

Using the Atacama Large Millimeter/submillimeter Array (ALMA), researchers obtained a critical clue to an underlying problem: how are widely separated twin stars formed? The team found very low mass newborn twin stars with misaligned rotation axes. This misalignment indicates that they were formed in a pair of fragmented gas clouds produced through turbulence, not via evolution of tightly-coupled twin. This finding strongly supports the turbulent fragmentation theory of binary star formation down to the substellar regime.

An international team of astronomers led by Jeong-Eun Lee in Kyung Hee University, Korea, observed the baby twin star system IRAS 04191+1523 with ALMA. Thanks to the high resolution of ALMA, the team successfully imaged the rotation of the gas disks around the very low mass twin stars and found that the rotation axes of the two stars are misaligned.

“This revelation is particularly interesting because both baby stars’ masses derived from our ALMA data are about 10% of the solar mass, which is very low. The formation of very low mass wide binary stars has been a mystery. But our result is strong evidence that wide binaries of these very low mass stars and even brown dwarfs can form in the same way as normal stars via turbulent fragmentation.” said Lee.

More than a half of the stars in the Universe are born as twins or multiple systems. Therefore, unveiling the formation mechanism of twin stars is crucial for a comprehensive understanding of stellar evolution.

There are two types of multiple stars: close systems and widely separated systems. Astronomers have witnessed a close system being formed via fragmentation of the gas disk around the firstborn stars [1]. On the other hand, there is no clear evidence on how widely separated systems are formed. Some researchers assume that a close system evolves into a wide system over millions of years due to dynamical interactions, but others guess that turbulence in a gas cloud fragments the cloud into smaller ones and stars are formed in each small cloud.

Aiming to find clues to the formation of wide binary systems, the researchers selected IRAS 04191+1523 as the target of their ALMA observations. The separation of the two stars is about 30 times the distance of Neptune from the Sun and classified as a wide binary. The age of the system is estimated to be far younger than half a million years old, therefore it is a good target to investigate the initial phase of wide binary formation.

Composite image of the very young baby twin star system IRAS 04191+1523. ALMA revealed the disks around two stars (white) and a common gas envelope (yellow). Red color shows the distribution of a dense cloud seen in far infrared light observed by the Herschel Space Observatory. Credit: ALMA (ESO/NAOJ/NRAO), Lee et al., ESA/Herschel/PACS

ESA/Herschel spacecraft

The team analyzed the signal from carbon monoxide molecules in the disks to derive their motion and found that the two disks around the baby stars are not aligned. The angle between the rotation axes of the disks is 77 degrees.

“The system is too young for the alignment of axes to have been modified by interactions,” said Lee [2], “so we conclude that this system was formed by the turbulent fragmentation of a cloud, not by disk fragmentation and migration.”

If a binary system is formed via disk fragmentation, the rotational moment of the gas aligns the axes of two stars. This alignment would be maintained even if the separation between the two is extended via tidal interactions. The misalignment of the axes in the infant system IRAS 04191+1523 clearly rejects this scenario.

Notes

ALMA revealed the detailed structure of the ongoing fragmentation of a gas disk around a young triple star system L1448 IRS 3B.

Previous ALMA observations of a young binary system HK Tauri show that the two disks are misaligned. However, HK Tauri is much more evolved than IRAS 04191+1523 and it is difficult to reject the possibility of orbit evolution to become a widely-separated system.

Additional information

These observation results were published as Lee et al. Formation of Wide Binaries by Turbulent Fragmentation in Nature Astronomy on June 30, 2017.

The research team members are:

Jeong-Eun Lee (Kyung Hee University), Seokho Lee (Kyung Hee University), Michel Dunham (State University of New York at Fredonia), Ken’ichi Tatematsu (National Astronomical Observatory of Japan / SOKENDAI), Minho Choi (Korea Astronomy and Space Science Institute), Edwin A. Bergin (University of Michigan), Neal J. Evans II (Korea Astronomy and Space Science Institute / The University of Texas at Austin)

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) (grant No. NRF-2015R1A2A2A01004769) and the Korea Astronomy and Space Science Institute under the R&D program (Project No. 2015-1-320-18) supervised by the Ministry of Science, ICT and Future Planning, Korea.

See the full article here .

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The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

From Stanford and Kavli: “Stanford Research Reveals Extremely Fine Measurements of Motion in Orbiting Supermassive Black Holes”

Stanford University

The Kavli Foundation

Observations from radio telescopes like this one appear to indicate that two black holes are orbiting each other, 750 million light years from Earth. (Credit: National Radio Astronomy Observatory)

Approximately 750 million light years from Earth lies a gigantic, bulging galaxy with two supermassive black holes at its center. These are among the largest black holes ever found, with a combined mass 15 billion times that of the sun. New research from Stanford University, published today (June 27) in Astrophysical Journal, has used long-term observation to show that one of the black holes seems to be orbiting around the other.

If confirmed, this is the first duo of black holes ever shown to be moving in relation to each other. It is also, potentially, the smallest ever recorded movement of an object across the sky, also known as angular motion.

“If you imagine a snail on the recently discovered Earth-like planet orbiting Proxima Centauri – a bit over four light years away – moving at one centimeter a second, that’s the angular motion we’re resolving here,” said co-author of the paper, Roger W. Romani, professor of physics at Stanford and a member of the Kavli Insititute for Particle Astrophysics and Cosmology. The team also included researchers from the University of New Mexico, the National Radio Observatory and the United States Naval Observatory.

The technical achievements of this measurement alone are reason for celebration. But the researchers also hope this impressive finding will offer insight into how black holes merge, how these mergers affect the evolution of the galaxies around them and ways to find other binary black-hole systems.

Miniscule movement

Over the past 12 years, scientists, led by Greg Taylor, a professor of physics and astronomy at the University of New Mexico, have taken snapshots of the galaxy containing these black holes – called radio galaxy 0402+379 – with a system of ten radio telescopes that stretch from the U.S. Virgin Islands to Hawaii and New Mexico to Alaska.

NRAO VLBA

NRAO VLBA

The galaxy was officially discovered back in 1995. In 2006, scientists confirmed it as a supermassive black-hole binary system with an unusual configuration.

“The black holes are at a separation of about seven parsecs, which is the closest together that two supermassive black holes have ever been seen before,” said Karishma Bansal, a graduate student in Taylor’s lab and lead author of the paper.

With this most recent paper, the team reports that one of the black holes moved at a rate of just over one micro-arcsecond per year, an angle about 1 billion times smaller than the smallest thing visible with the naked eye. Based on this movement, the researchers hypothesize that one black hole may be orbiting around the other over a period of 30,000 years.
Two holes in ancient galaxy

Although directly measuring the black hole’s orbital motion may be a first, this is not the only supermassive black-hole binary ever found. Still, the researchers believe that 0402+379 likely has a special history.

“We’ve argued it’s a fossil cluster,” Romani said. “It’s as though several galaxies coalesced to become one giant elliptical galaxy with an enormous halo of X-rays around it.”

Researchers believe that large galaxies often have large black holes at their centers and, if large galaxies combine, their black holes eventually follow suit. It’s possible that the apparent orbit of the black hole in 0402+379 is an intermediary stage in this process.

“For a long time, we’ve been looking into space to try and find a pair of these supermassive black holes orbiting as a result of two galaxies merging,” Taylor said. “Even though we’ve theorized that this should be happening, nobody had ever seen it, until now.”

A combination of the two black holes in 0402+379 would create a burst of gravitational radiation, like the famous bursts recently discovered by the Laser Interferometer Gravitational-Wave Observatory, but scaled up by a factor of a billion.

Caltech/MIT Advanced aLigo Hanford, WA, USA installation

Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

ESA/eLISA the future of gravitational wave research

It would be the most powerful gravitational burst in the universe, Romani said. This kind of radiation burst happens to be what he wrote his first-ever paper on when he was an undergraduate.

Very slow dance

This theorized convergence between the black holes of 0402+379, however, may never occur. Given how slowly the pair is orbiting, the scientists think the black holes are too far apart to come together within the estimated remaining age of the universe, unless there is an added source of friction. By studying what makes this stalled pair unique, the scientists said they may be able to better understand the conditions under which black holes normally merge.

Romani hopes this work could be just the beginning of heightening interest in unusual black-hole systems.

“My personal hope is that this discovery inspires people to go out and find other systems that are even closer together and, hence, maybe do their motion on a more human timescale,” Romani said. “I would sure be happy if we could find a system that completed orbit within a few decades so you could really see the details of the black holes’ trajectories.”

Additional co-authors on this paper are A.B. Peck, Gemini Observatory (formerly of the National Radio Astronomy Observatory); and R.T. Zavala, U.S. Naval Observatory.

This work was funded by NASA and the National Radio Astronomical Observatory.

See the full Stanford article here .
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The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

From GBO: “GBT Captures Orion Blazing Bright in Radio Light”

Green Bank Radio Telescope, West Virginia, USA

Green Bank Observatory

A ribbon of ammonia — a tracer of star-forming gas — in the Orion Nebula as seen with the GBT. — GBO/AUI/NSF

A team of astronomers has unveiled a striking new image of the Orion Molecular Cloud (OMC) – a bustling stellar nursery teeming with bright, young stars and dazzling regions of hot, glowing gas.

The researchers used the National Science Foundation’s (NSF) Green Bank Telescope (GBT) in West Virginia to study a 50 light-year long filament of star-forming gas that is wending its way through the northern portion of the OMC known as Orion A.

The GBT rendered this image by detecting the faint radio signals naturally emitted by molecules of ammonia that suffuse interstellar clouds. Scientists study these molecules to trace the motion and temperature of vast swaths of star-forming gas.

These observations are part of the first data release from a large campaign known as the Green Bank Ammonia Survey. Its purpose is to map all the star-forming ammonia and other key tracer molecules in a massive structure known as the Gould Belt.

The Gould Belt is an extended ribbon of bright, massive stars stretching about 3,000 light-years in an arc across the sky. This first release covers four distinct Gould Belt clouds, one located in Taurus, one in Perseus, one in Ophiuchus, and Orion A North in Orion.

“We hope to use these data to understand better how large clouds of gas in our galaxy collapse to form new stars,” said Rachel Friesen, one of the collaboration’s co-principal investigators and, until 31 May 2017, a Dunlap Fellow at the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto in Canada. “The new data are critical to assessing whether certain gas clouds and filaments are stable and enduring features or if they are undergoing collapse and forming new stars.”

A ribbon of ammonia — a tracer of star-forming gas — in the Orion Nebula as seen with the GBT (orange). Background in blue is a WISE telescope infrared image showing the dust in the region. — GBO/AUI/NSF

NASA/WISE Telescope

Prior ammonia observations by many of the survey’s co-authors have targeted smaller portions of similar star-forming clouds. In these individual studies, the researchers identified sharp transitions in the amount of turbulence between the larger cloud and the smaller-scale star-forming cores, studied the stability against gravitational collapse of the gas within a young protocluster, and investigated how mass builds up along gas filaments and flows into stellar cluster-forming regions.

“These data provide a unique view of the cold dense gas involved in forming stars like our sun,” said Jaime E. Pineda, the collaboration’s other co-principal investigator, with the Max-Planck Institute for Extraterrestrial Physics in Garching, Germany. “We hope they can also help us determine how much rotation is present in the regions that will form stars; this is crucial to understand how protoplanetary disks are formed.”

The new GBT image is combined with an infrared one taken with NASA’s Wide-field Infrared Survey Explorer (WISE) telescope. The composite image illustrates how star-forming gas in this region relates to the bright stars and dark, dusty regions of the nebula.

The 100-meter GBT, which is located in the National Radio Quiet Zone, is exquisitely sensitive and uniquely able to study the molecular composition of star-forming clouds and other objects in the cosmos. Future observations of the Gould Belt will provide greater insights into the conditions that give rise to stars like our sun and planets like Earth.

The Green Bank Observatory (GBO) is a facility of the National Science Foundation operated under a cooperative agreement by Associated Universities, Inc.

This research is presented in a paper titled The Green Bank Ammonia Survey (GAS): First results of NH3 mapping the Gould Belt, R. Friesen and J. Pineda et al. appearing in the Astrophysical Journal Supplements

See the full article here .

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Mission Statement

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.

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.