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  • richardmitnick 12:00 pm on June 14, 2020 Permalink | Reply
    Tags: "Las Cumbres Observatory Robotic Telescopes Provide Vital Data for Recent Astronomical Discoveries", Asteroseismology, , , , , Las Cumbres Observatory Global Telescope Network   

    From Las Cumbres Observatory Global Telescope Network: “Las Cumbres Observatory Robotic Telescopes Provide Vital Data for Recent Astronomical Discoveries” 

    LCOGT bloc

    From Las Cumbres Observatory Global Telescope Network

    LCO 2m and 1m telescope enclosures at Siding Spring Observatory in Australia.

    While many telescopes around the world have been closed during the COVID-19 pandemic, Las Cumbres Observatory has continued to operate their global network of robotic telescopes where it is safe and allowed to do so. Traditional telescopes can be dangerous for humans during a pandemic because they rely on astronomers to travel to the facility and on teams of human operators and engineers working together in sometimes close quarters. In contrast, robotic facilities operate with no human intervention, except astronomers submitting new observations over the internet, and occasional software and hardware maintenance.

    “Las Cumbres Observatory is fortunate to be able to continue to provide rich data to scientists around the world during these challenging times,” said Lisa Storrie-Lombardi, the President and Observatory Director. LCO observations are featured in several recent discoveries.

    A study led by Tim Bedding of the University of Sydney, using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) in conjunction with LCO, was published on May 14 in Nature.

    NASA/MIT TESS replaced Kepler in search for exoplanets

    The study showed that certain types of stars slightly more massive than the Sun, known as delta Scuti stars, pulsate with previously unknown frequencies. This solves a longstanding mystery, and will allow scientists to learn about their interiors by studying their pulsations through asteroseismology, analogous to how seismologists can learn about the Earth’s interior from studying Earthquakes. While NASA’s TESS satellite is sensitive to small stellar pulsations, it can’t split the star’s like up into a spectrum (a rainbow), which can provide complementary information. That was the job of LCO’s robotic NRES spectrographs.

    Artist’s impression of a Delta Scuti pulsating star, courtesy NASA Goddard Space Flight Center. The stars rotate so rapidly that they are slightly flattened.

    On May 26, the University of Hawai’i announced that the Asteroid Terrestrial-Impact Last Alert System (ATLAS) had discovered an unusual comet.

    ATLAS telescope, First Asteroid Terrestrial-impact Last Alert system (ATLAS) fully operational 8/15/15 Haleakala , Hawaii, USA, Altitude 4,205 m (13,796 ft)

    Recent data have shown that the Jupiter Trojan object 2019 LD2 is in fact a comet with an unusual orbit. The ATLAS discovery was confirmed with follow-up observations by the LCO network. The object was reclassified from an asteroid to a comet by the Minor Planet Center, as its orbit is unstable compared to Jupiter Trojans and it has a distinctive tail. Observations of this rare comet are continuing.

    (Left) ATLAS image of P/2019 LD2 (indicated by two red lines) is almost lost in the field of stars, courtesy University of Hawai’i.

    A study led by Monash University in Australia has observed, for the first time, the full process of an accreting neutron star reaching an x-ray outburst. While the process was previously thought to take place over 3 or 4 days, the new study revealed activity over 12 days. LCO provided rapid ground-based observations, while telescopes in space, like NASA’s Swift satellite, and the NICER instrument on the International Space Station provided ultraviolet and X-ray data that cannot be taken from Earth.

    NASA Neil Gehrels Swift Observatory

    NASA/NICER on the ISS

    An accreting pulsar, courtesy NASA/JPL-Caltech.

    See the full article here.


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    LCOGT Las Cumbres Observatory Global Telescope Network

    Las Cumbres Observatory Global Telescope Network is an integrated set of robotic telescopes, distributed around the world. The network currently includes two 2-meter telescopes, sited in Hawaii and eastern Australia, nine 1-meter telescopes, sited in Chile, South Africa, eastern Australia, and Texas, and three 0.4-meter telescopes, sited in Chile and the Canary Islands.

    LCOGT map

  • richardmitnick 1:59 pm on May 21, 2020 Permalink | Reply
    Tags: "New gravitational-wave model can bring neutron stars into even sharper focus", Asteroseismology, , , ,   

    From University of Birmingham UK via phys.org: “New gravitational-wave model can bring neutron stars into even sharper focus” 

    From University of Birmingham UK



    May 21, 2020

    The results from a numerical relativity simulation of two merging neutron stars similar to GW170817. Credit: University of Birmingham

    Gravitational-wave researchers at the University of Birmingham have developed a new model that promises to yield fresh insights into the structure and composition of neutron stars.

    The model shows that vibrations, or oscillations, inside the stars can be directly measured from the gravitational-wave signal alone. This is because neutron stars will become deformed under the influence of tidal forces, causing them to oscillate at characteristic frequencies, and these encode unique information about the star in the gravitational-wave signal.

    This makes asteroseismology—the study of stellar oscillations—with gravitational waves from colliding neutron stars a promising new tool to probe the elusive nature of extremely dense nuclear matter.

    Neutron stars are the ultradense remnants of collapsed massive stars. They have been observed in the thousands in the electromagnetic spectrum and yet little is known about their nature. Unique information can be gleaned through measuring the gravitational waves emitted when two neutron stars meet and form a binary system. First predicted by Albert Einstein, these ripples in spacetime were first detected by the Advanced Laser Interferometer Gravitational Wave Observatory (LIGO) in 2015.

    By utilising the gravitational wave signal to measure the oscillations of the neutron stars, researchers will be able to discover new insights into the interior of these stars. The study is published in Nature Communications.

    Dr. Geraint Pratten, of the University of Birmingham’s Gravitational Wave Institute, is lead author of the study. He explained: “As the two stars spiral around each other, their shapes become distorted by the gravitational force exerted by their companion. This becomes more and more pronounced and leaves a unique imprint in the gravitational wave signal.

    “The tidal forces acting on the neutron stars excite oscillations inside the star giving us insight into their internal structure. By measuring these oscillations from the gravitational-wave signal, we can extract information about the fundamental nature and composition of these mysterious objects that would otherwise be inaccessible.”

    The model developed by the team enables the frequency of these oscillations to be determined directly from gravitational-wave measurements for the first time. The researchers used their model on the first observed gravitational-wave signal from a binary neutron star merger—GW170817.

    Co-lead author, Dr. Patricia Schmidt, added: “Almost three years after the first gravitational-waves from a binary neutron star were observed, we are still finding new ways to extract more information about them from the signals. The more information we can gather by developing ever more sophisticated theoretical models, the closer we will get to revealing the true nature of neutron stars.”

    Next generation gravitational wave observatories planned for the 2030s, will be capable of detecting far more binary neutron stars and observing them in much greater detail than is currently possible. The model produced by the Birmingham team will make a significant contribution to this science.

    “The information from this initial event was limited as there was quite a lot of background noise that made the signal difficult to isolate,” says Dr. Pratten. “With more sophisticated instruments we can measure the frequencies of these oscillations much more precisely and this should start to yield some really interesting insights.”

    See the full article here .


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    Birmingham has been challenging and developing great minds for more than a century. Characterised by a tradition of innovation, research at the University has broken new ground, pushed forward the boundaries of knowledge and made an impact on people’s lives. We continue this tradition today and have ambitions for a future that will embed our work and recognition of the Birmingham name on the international stage.

  • richardmitnick 4:35 pm on January 13, 2020 Permalink | Reply
    Tags: "The Interiors of Stars", Asteroseismology, , , , , , , Improving our understanding of the interiors of intermediate mass stars.   

    From Harvard-Smithsonian Center for Astrophysics: “The Interiors of Stars” 

    Harvard Smithsonian Center for Astrophysics

    From Harvard-Smithsonian Center for Astrophysics

    January 10, 2020

    An illustration of vibration modes in the Sun. Astronomers have used the TESS mission to study for the first time stellar oscillations in intermeidate mass stars.

    NASA/MIT TESS replaced Kepler in search for exoplanets

    Kosovichev et al., Structure and Rotation of the Solar Interior: Initial Results from the MDI Medium-L Program [Springer]


    The interiors of stars are largely mysterious regions because they are so difficult to observe. Our lack of understanding about the physical processes there, like rotation and the mixing of hot gas, introduces considerable ambuguity about how stars shine and how they evolve. Stellar oscillations, detected through brightness fluctuations, offer one way to probe these subsurface regions. In the Sun, these vibrations are due to pressure waves generated by turbulence in its outer layers (the layers dominated by convective gas motions). Helioseismology is the name given to the study of these oscillations in the Sun, and asteroseismology is the term used for the same study in other stars.

    Astronomers have long detected strong brightness variations in other stars, for example the class of Cepheid variable stars used to calibrate the cosmic distance scale, but the small, solar-like oscillations driven by convection near the star’s surface are much harder to see. Over the past few decades, space telescopes have successfully applied astroseismology to solar-type stars spanning many stages of stellar life. CfA astronomer Dave Latham was a member of a large team of astronomers who used the new TESS (Transiting Exoplanet Survey Satellite) datasets to study the interiors of the class of intermediate mass stars known as δ Sct and γ Dor stars. These stars are more massive than the Sun but not large enough to burn through their hydrogen fuel very rapidly and die as supernovae. Pulsations generally arise principally from one of two processes, those dominated by pressure (where the gas pressure restores perturbations) or by gravity (where buoyancy does). In these intermediate-mass stars both of these processes can be important, with pulsations having typical periods of roughly about six hours. The complexity of the combined processes, among other things, results in these intermediate-mass stars coming in a veritable zoo of variability types, and this variety offers astronomers more ways to test models of stellar interiors.

    The astronomers analyzed TESS data on 117 of these stars using observations taken every two minutes; accurate distances to the stars (and hence accurate luminosities) were obtained from Gaia satellite measurements.

    ESA/GAIA satellite

    The team was able for the first time to fully test and successfully refine models of pulsation for these stars. They found, for example, that gas mixing in the outer envelope plays an important role. They also spotted many higher-frequency pulsators, thereby identifying promising targets for future studies. Not least, they showed that the TESS mission has enormous potential not just for studying exoplanets, but also for improving our understanding the interiors of intermediate mass stars.

    Science paper:
    The First View of δ Scuti and γ Doradus Stars with the TESS Mission,

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

  • richardmitnick 2:39 pm on December 6, 2019 Permalink | Reply
    Tags: "New clues to the Milky Way’s age", , Asteroseismology, , , , ,   

    From COSMOS Magazine: “New clues to the Milky Way’s age” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    06 December 2019

    Star-quake vibrations suggest ‘thick disc’ is 10 billion years old.

    Infrared cameras reveal the stars of the crowded galactic centre region of the Milky Way.
    Credit: NASA

    Credit: NASA/JPL Caltech/R.Hurt/SSC

    The Milky Way’s “thick disc” is about 10 billion years old, according to an international team of scientists.

    They used data from NASA’s now-defunct Kepler space telescope to study star-quake vibrations – and appear to have cleared up a long-standing mystery.

    “Earlier data about the age distribution of stars in the disc didn’t agree with the models constructed to describe it, but no one knew where the error lay – in the data or the models,” says Sanjib Sharma from Australia’s ARC Centre of Excellence for All Sky Astrophysics in Three Dimensions (ASTRO-3D).

    “Now we’re pretty sure we’ve found it.”

    Sharma is lead author of a paper published in the Monthly Notices of the Royal Astronomical Society. He worked with 37 other researchers from Australia, the US, Germany, Austria, Italy, Denmark, Slovenia and Sweden.

    The Milky Way – like many spiral galaxies – consists of two disc-like structures.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt. The bar is visible in this image

    The thick disc contains only about 20% of the galaxy’s stars and, based on its vertical puffiness and composition, is thought to be the older.

    To find out just how much older, Sharma and colleagues used asteroseismology – a way of identifying the internal structures of stars by measuring their oscillations from star quakes.

    “The frequencies produced tell us things about the stars’ internal properties, including their age,” says ASTRO-3D’s Dennis Stello. “It’s a bit like identifying a violin as a Stradivarius by listening to the sound it makes.”

    The researchers don’t “hear” the sound generated by star-quakes. Instead, they look for how the internal movement is reflected in changes to brightness.

    “Stars are just spherical instruments full of gas,” says Sharma, “but their vibrations are tiny, so we have to look very carefully.

    “The exquisite brightness measurements made by Kepler were ideal for that. The telescope was so sensitive it would have been able to detect the dimming of a car headlight as a flea walked across it.”

    The data delivered by the telescope during the four years after it launched in 2009 presented a problem. It suggested there were more younger stars in the thick disc than models predicted.

    The question confronting astronomers was stark: were the models wrong, or was the data incomplete?

    In 2013, however, Kepler broke down, and NASA reprogrammed it to continue working on a reduced capacity – a period that became known as the K2 mission. The project involved observing many different parts of the sky for 80 days at a time.

    This allowed for a fresh spectroscopic analysis. This revealed that the chemical composition incorporated in the existing models for stars in the thick disc was wrong, which affected the prediction of their ages.

    Taking this into account, the researchers found that the observed asteroseismic data now fell into “excellent agreement” with model predictions.

    See the full article here .

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  • richardmitnick 4:44 pm on April 1, 2019 Permalink | Reply
    Tags: Asteroseismology, , , , , , , The planet TOI 197.01 (TOI is short for “TESS Object of Interest”)   

    From Iowa State University: “Data flows from NASA’s TESS Mission, leads to discovery of Saturn-sized planet” 

    From Iowa State University

    Mar 27, 2019

    Steve Kawaler
    Physics and Astronomy

    Mike Krapfl
    News Service

    A “hot Saturn” passes in front of its host star in this illustration. Astronomers who study stars used “starquakes” to characterize the star, which provided critical information about the planet. See a video illustration of the planet orbiting the star. llustration by Gabriel Perez Diaz, Instituto de Astrofísica de Canarias.

    Astronomers who study stars are providing a valuable assist to the planet-hunting astronomers pursuing the primary objective of NASA’s new TESS Mission.

    NASA/MIT TESS replaced Kepler in search for exoplanets

    In fact, asteroseismologists – stellar astronomers who study seismic waves (or “starquakes”) in stars that appear as changes in brightness – often provide critical information for finding the properties of newly discovered planets.

    This teamwork enabled the discovery and characterization of the first planet identified by TESS for which the oscillations of its host star can be measured.

    The planet – TOI 197.01 (TOI is short for “TESS Object of Interest”) – is described as a “hot Saturn” in a recently accepted scientific paper [The Astronomical Journal by an international team of 141 astronomers. Daniel Huber, an assistant astronomer at the University of Hawaii at Manoa’s Institute for Astronomy, is the lead author of the paper. Steve Kawaler, a professor of physics and astronomy; and Miles Lucas, an undergraduate student, are co-authors from Iowa State University.]. That’s because the planet is about the same size as Saturn and is also very close to its star, completing an orbit in just 14 days, and therefore very hot.

    “This is the first bucketful of water from the firehose of data we’re getting from TESS,” Kawaler said.

    TESS – the Transiting Exoplanet Survey Satellite, led by astrophysicists from the Massachusetts Institute of Technology – launched from Florida’s Cape Canaveral Air Force Station on April 18, 2018. The spacecraft’s primary mission is to find exoplanets, planets beyond our solar system. The spacecraft’s four cameras are taking nearly month-long looks at 26 vertical strips of the sky – first over the southern hemisphere and then over the northern. After two years, TESS will have scanned 85 percent of the sky.

    Astronomers (and their computers) sort through the images, looking for transits, the tiny dips in a star’s light caused by an orbiting planet passing in front of it.

    Planet transit. NASA/Ames

    NASA’s Kepler Mission – a predecessor to TESS – looked for planets in the same way, but scanned a narrow slice of the Milky Way galaxy and focused on distant stars.

    TESS is targeting bright, nearby stars, allowing astronomers to follow up on its discoveries using other space and ground observations to further study and characterize stars and planets. In another paper recently published online by The Astrophysical Journal Supplement Series, astronomers from the TESS Asteroseismic Science Consortium (TASC) identified a target list of sun-like oscillating stars (many that are similar to our future sun) to be studied using TESS data – a list featuring 25,000 stars.

    Kawaler – who witnessed the launch of Kepler in 2009, and was in Florida for the launch of TESS (but a last-minute delay meant he had to miss liftoff to return to Ames to teach) – is on the seven-member TASC Board. The group is led by Jørgen Christensen-Dalsgaard of Aarhus University in Denmark.

    TASC astronomers use asteroseismic modeling to determine a host star’s radius, mass and age. That data can be combined with other observations and measurements to determine the properties of orbiting planets.

    In the case of host star TOI-197, the asteroseismolgists used its oscillations to determine it’s about 5 billion years old and is a little heavier and larger than the sun. They also determined that planet TOI-197.01 is a gas planet with a radius about nine times the Earth’s, making it roughly the size of Saturn. It’s also 1/13th the density of Earth and about 60 times the mass of Earth.

    Those findings say a lot about the TESS work ahead: “TOI-197 provides a first glimpse at the strong potential of TESS to characterize exoplanets using asteroseismology,” the astronomers wrote in their paper.

    Kawaler is expecting that the flood of data coming from TESS will also contain some scientific surprises.

    “The thing that’s exciting is that TESS is the only game in town for a while and the data are so good that we’re planning to try to do science we hadn’t thought about,” Kawaler said. “Maybe we can also look at the very faint stars – the white dwarfs – that are my first love and represent the future of our sun and solar system.”

    See the full article here .


    Please help promote STEM in your local schools.

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    Iowa State University is a public, land-grant university, where students get a great academic start in learning communities and stay active in 800-plus student organizations, undergrad research, internships and study abroad. They learn from world-class scholars who are tackling some of the world’s biggest challenges — feeding the hungry, finding alternative fuels and advancing manufacturing.

    Iowa Agricultural College and Model Farm (now Iowa State University) was officially established on March 22, 1858, by the legislature of the State of Iowa. Story County was selected as a site on June 21, 1859, and the original farm of 648 acres was purchased for a cost of $5,379. The Farm House, the first building on the Iowa State campus, was completed in 1861, and in 1862, the Iowa legislature voted to accept the provision of the Morrill Act, which was awarded to the agricultural college in 1864.

    Iowa State University Knapp-Wilson Farm House. Photo between 1911-1926

    Iowa Agricultural College (Iowa State College of Agricultural and Mechanic Arts as of 1898), as a land grant institution, focused on the ideals that higher education should be accessible to all and that the university should teach liberal and practical subjects. These ideals are integral to the land-grant university.

    The first official class entered at Ames in 1869, and the first class (24 men and 2 women) graduated in 1872. Iowa State was and is a leader in agriculture, engineering, extension, home economics, and created the nation’s first state veterinary medicine school in 1879.

    In 1959, the college was officially renamed Iowa State University of Science and Technology. The focus on technology has led directly to many research patents and inventions including the first binary computer (the ABC), Maytag blue cheese, the round hay baler, and many more.

    Beginning with a small number of students and Old Main, Iowa State University now has approximately 27,000 students and over 100 buildings with world class programs in agriculture, technology, science, and art.

    Iowa State University is a very special place, full of history. But what truly makes it unique is a rare combination of campus beauty, the opportunity to be a part of the land-grant experiment, and to create a progressive and inventive spirit that we call the Cyclone experience. Appreciate what we have here, for it is indeed, one of a kind.

  • richardmitnick 12:44 pm on February 5, 2019 Permalink | Reply
    Tags: Asteroseismology, , , , , , Massive collision in the planetary system Kepler 107   

    From Instituto de Astrofísica de Canarias – IAC via Manu: “Massive collision in the planetary system Kepler 107” 

    From Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.


    From Instituto de Astrofísica de Canarias – IAC

    Feb. 4, 2019
    Savita Mathur

    Two of the planets which are orbiting the star Kepler 107 could be the result of an impact similar to that which affected the Earth to produce the Moon. An international team whose members include a researcher from the Instituto de Astrofísica de Canarias and the University of La Laguna, are publishing the results of this work today in the journal Nature Astronomy.

    Hydrodynamics simulation of a high-speed frontal collision between two planets of the landmass. The temperature range of the material is represented by four colors: gray, orange, yellow and red, where the gray is the coldest and the hottest red. Such collisions expel a large amount of silicate mantle material leaving a remaining planet high iron and similar to the observed characteristics of high density Kepler-107c. Credit: ZM Leinhardt and T. Denman (Bristol Univ.)

    Since, in 1995 the first extrasolar planet was discovered almost 4,000 planets have been found around the nearest stars. This allows us to study a large variety of configurations for these planetary systems. The evolution of the planets orbiting other stars can be affected, mainly, by two phenomena: the evaporation of the upper layers of the planet due to the effect of the X-rays and ultraviolet emitted by the central star, and by the impacts of other celestial bodies of the size of a planet.

    The former effect has been observed a number of times in extrasolar systems, but until now there have been no proof of the existence of major impacts, as has apparently occurred in the Kepler 107 system.

    The central star, Kepler 107, is a bit bigger than the Sun, and has four planets rotating around it; it was the two innermost planets which drew the interest of the astrophysicists. Using data from NASA’s Kepler satellite and from the National Galileo Telescope (TNG) at the Roque de los Muchachos Observatory (Garafía, La Palma, Canary Islands), the team determined the parameters of the star, and measured the radii and masses of these planets. Although the innermost two have similar radii their masses are very different. In fact the second is three times denser than the first.


    After nine years in deep space, collecting data revealed that
    our night sky was full of thousands of millions of hidden planets, more
    planets even star Kepler space telescope NASA has
    run out of fuel for other scientific operations. NASA has decided to withdraw
    the spacecraft in its current orbit safely and away from Earth. Kepler leaves a
    legacy of more than 2,600 discoveries of planets outside our solar system,
    many of which could be promising places for life.
    More information: http://www.nasa.gov/kepler .
    Credit: NASA / Ames Research Center / W. Stenzel / D. Rutter.
    Last updated: November 2, 2018. Editor: Rick Chen.

    INAF Telescopio Nazionale Galileo, a 3.58-meter Italian telescope, located at the Roque de los Muchachos Observatory on the island of La Palma in the Canary Islands, Spain, Altitude 2,396 m (7,861 ft)

    The extraordinarily high density of the planet Kepler 107c is more than double that of the Earth. This exceptional density for a planet has intrigued researchers, and suggests that its metallic core, its densest part, is anomalously big for a planet.

    This would be still considered normal if it were not for the prediction that photo-evaporation causes the densest planet in a system to be the nearest to its star. To explain how it is possible that, in this case, the nearest has only half the density of the second, the hypothesis was proposed that the planet Kepler 107c was formed as the result of a major impact. This impact must have ripped away its outer layers, thus leaving the central core as a much bigger fraction than before. After tests carried out via simulations, this hypothesis seems to be the most likely.

    This study will allow us to better understand the formation and evolution of exoplanets. Specifically it picks out the importance of the relationship between stellar physics and exoplanetary research. “We need to know the star to better understand the planets which are in orbit around it” says Savita Mathur, a researcher at the IAC in Tenerife, and one of the authors of the article. “In this study we made a seismic analysis to estimate the parameters of the star which hosts the planet. Asteroseismology is playing a key role in the field of the exoplanets, because it has been shown that it is one of the best methods for a precise characterization of the stars”. That is why during the past decade it has become one of the main methods for characterizing stars, and it will remain so in the coming years, thanks to the space missions for discovering exoplanets: TESS (NASA) and PLATO (ESA).



    See the full article here.

    Please help promote STEM in your local schools.

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    The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

    The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
    The Centro de Astrofísica en La Palma (CALP)
    The Observatorio del Teide (OT), in Izaña (Tenerife).

    These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

    The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

    The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

    The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

    The IAC’s research programme includes astrophysical research and technological development projects.

    The IAC is also involved in researcher training, university teaching and outreachactivities.

    The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.

    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, SpainGran Telescopio CANARIAS, GTC

  • richardmitnick 3:24 pm on September 23, 2018 Permalink | Reply
    Tags: 'Latitudinal differential rotation’, Asteroseismology, Latitudinal differential rotation can be much stronger in some stars than in the Sun, , , Photometric light curves, Solar equators rotate faster than higher latitudes, , Stars are too far away to be resolved in astronomical images. However scientists can indirectly obtain spatial information about stellar interiors using stellar oscillations, Stellar rotation, Stellar rotation is determined by tracking starspots at different latitudes in photometric light curves   

    From Max Planck Institute for Solar System Research: “A new twist on stellar rotation” 

    From Max Planck Institute for Solar System Research

    September 21, 2018

    Prof. Dr. Laurent Gizon
    Max Planck Institute for Solar System Research, Göttingen
    +49 551 384979-439

    Dr. Birgit Krummheuer
    Press Office
    Max Planck Institute for Dynamics and Self-Organization, Göttingen
    +49 551 5176-668

    Like our sun, distant stars are rotating spheres of hot gas.

    Sun-like stars rotate differentially, with the equator rotating faster than the higher latitudes. The green arrows in the figure represent rotation speed in the stellar convection zone. Differential rotation is inferred from the oscillatory motions of the star seen as orange/blue shades on the right side of the picture. Differential rotation is thought to be an essential ingredient for generating magnetic activity and starspots. © MPS / MarkGarlick.com

    Stars, however, do not rotate like solid spheres: regions at different latitudes rotate at different rates. A group of researchers from New York University and the Max Planck Institute for Solar System Research (MPS) in Germany has now measured the rotational patterns of a sample of Sun-like stars.

    They have identified 13 stars that rotate in a similar fashion as our Sun: their equators rotate faster than their mid latitudes. This rotation pattern is, however, much more pronounced than in the Sun: the stars’ equators are found to rotate up to twice as quickly as their mid-latitudes. This difference in rotation speed is much larger than theories had suggested.

    What do we know about distant stars aside from their brightness and colors? Is our Sun a typical star? Or does it show certain properties that make it special, or maybe even unique? One property that is not fully understood is rotation. In its outer layers the Sun has a rotation pattern that scientists refer to as `latitudinal differential rotation’. This means that different latitudes rotate at different rates. While at the Sun’s equator one full rotation takes approximately 25 days, the higher latitudes rotate more slowly. Near the Sun’s poles, one full rotation takes approximately 31 days.

    In their new work the scientists studied the rotation of 40 stars that resemble the Sun with respect to mass. Among those, the 13 stars for which differential rotation could be measured with confidence all show solar-like differential rotation: equators rotate faster than higher latitudes. In some cases, however, the difference in rotational speed between the equator and the mid-latitudes is much larger than in the Sun.

    Classically, stellar rotation is determined by tracking starspots at different latitudes in photometric light curves. This method is limited, however, because we do not know the latitudes of the starspots. “Using observations from NASA’s Kepler mission we can now probe the interior of stars with asteroseismology and determine their rotational profiles at different latitudes and depths”, says Laurent Gizon, director at MPS.

    Stars are too far away to be resolved in astronomical images. They are point like. However scientists can indirectly obtain spatial information about stellar interiors using stellar oscillations. Stars undergo global acoustic oscillations that are excited by convective motions in their outer layers. Different modes of oscillations probe different regions in a star. Thus the frequencies of oscillation inform us about different regions. In this study the scientists used stellar oscillations to measure rotation at different latitudes in the outer convection zone. “Modes of oscillation that propagate in the direction of rotation move faster than the modes that propagate in the opposite direction, thus their frequencies are slightly different”, says Gizon.

    “Our best measurements all reveal stars with solar-like rotation”, says Gizon. The most surprising aspect of this research is that latitudinal differential rotation can be much stronger in some stars than in the Sun. The scientists did not expect such large values, which are not predicted by numerical models.

    This work is important as it shows that asteroseismology has fantastic potential to help us understand the inner workings of stars. “Information about stellar differential rotation is key to understanding the processes that drive magnetic activity”, says Gizon. Combining information about internal rotation and activity, together with modeling, will most likely reveal the root causes of magnetic activity in stars. However, many more Sun-like stars must be studied for this to happen. In 2026 the European Space Agency will launch the PLATO mission (an exoplanet mission, like Kepler) to characterize tens of thousands of bright Sun-like stars using precision asteroseismology.


    Large-number statistics will be key to studying the physics of stars and their evolution.

    Science paper:
    Asteroseismic detection of latitudinal differential rotation in 13 Sun-like stars
    Science, 21. September 2018

    See the full article here .


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    Stem Education Coalition

    Max Planck Institute for Solar System Research

    The Max Planck Institute for Solar System Research has had an eventful history – with several moves, changes of name, and structural developments. The first prototype of the current institute was founded in 1934 in Mecklenburg; it moved to Katlenburg-Lindau in 1946. Not just the location of the buildings changed – the topic of research also moved, from Earth to outer space. In the first decades the focus of research was the stratosphere and ionosphere of the Earth, but since 1997 the institute exclusively researches the physics of planets and the Sun. In January 2014 the Max Planck Institute for Solar System Research has relocated to it’s new home: a new building in Göttingen close to the Northern Campus of the University of Göttingen.

  • richardmitnick 2:33 pm on March 2, 2018 Permalink | Reply
    Tags: Asteroseismology, , , Bart Bok, , , KIC 08626021, UA's Bok Telescope,   

    From University of Arizona: “Bok to the Future: Sounding the Depths of a Dying Star” 

    U Arizona bloc

    University of Arizona

    March 1, 2018
    Daniel Stolte

    A small, aging telescope can still do mighty science, even helping astrophysicists undertake a virtual journey to the center of a dead star. What they discovered may change our knowledge of how stars — including our sun — evolve and age.

    Vintage workhorse: Dedicated in 1969 and named after Bart Bok, who was director of the UA’s Steward Observatory at the time, the UA’s Bok Telescope has pointed its 90-inch primary mirror at the skies every night except Christmas Eve and a maintenance period during the summer rainy season. (Image courtesy of Steward Observatory)

    U Arizona Steward Observatory at Kitt Peak, AZ, USA, altitude 2,096 m (6,877 ft)

    There are times when having the latest and greatest in technology is not the only thing that counts, even in a field where success depends critically on technological advances, as it does in astronomy.

    This is the story of a telescope and instrument considered “vintage” by today’s standards, and how they allowed one group of researchers to succeed in making a discovery they wouldn’t otherwise have been able to make, had they relied exclusively on the advanced satellite instrument that collected the initial data.

    It all began when data taken by NASA’s Kepler spacecraft revealed that a white dwarf named KIC 08626021, the “corpse” of a star not unlike the sun, was pulsating. That in itself was not unusual. By the time a star becomes a white dwarf, it has burned all of its nuclear fuel and is cooling down for the last time. At several points during the cooling process, a white dwarf becomes unstable, causing it to pulsate simultaneously at multiple different frequencies. These deep vibrations are the key to unveiling the interior of the stellar remnant. The internal chemical stratification of the white dwarf star creates a unique signature in the modulation of the light coming out of the star, which, once deciphered, allows scientists to obtain a cartography of its internal structure.

    Astronomers who study how stars are born, how they age and how they die believe that white dwarfs, especially pulsators such as KIC 08626021, give us a preview of the afterlife of our sun, long after it has consumed our planet in its fiery throes of death. In fact, the vast majority of stars in the universe will end up as white dwarfs. These stellar relics retain the imprints of past physical processes such as nuclear burning and episodes of convective mixing — phenomena that are not all that well understood in the actual modeling of stellar evolution theory. To have a glimpse at the internal structure and composition of these stars allows scientists to better elucidate the physics at play during all phases of stellar evolution, including those occurring in our sun.

    But in the case of KIC 08626021, something was off. The pulsations that Kepler observed in this star were too rapid for the type of white dwarf that it was initially reported to be, based on the models astronomers commonly use to investigate these stars.

    “A light spectrum taken with the William Herschel Telescope on La Palma in the Canary Islands suggested that its atmosphere contained only helium and no hydrogen,” says Elizabeth Green, an associate astronomer at the University of Arizona’s Steward Observatory who helped decipher the star’s true nature.

    ING 4 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands, 2,396 m (7,861 ft)

    “This was a problem because a white dwarf of that type should have a cooler temperature and therefore slower oscillations than what Kepler saw.”

    Journey to the Center of a Star

    Green was part of an international team of astrophysicists from Toulouse, France; Montreal; Tucson; Liège, Belgium; and Beijing who set out to unravel the internal composition of KIC 08626021 by deciphering the brightness oscillations observed at its surface, using asteroseismology, a technique similar to methods that geophysicists use to study the structure of the Earth, analyzing the seismic waves caused by earthquakes. The researchers published their results in a recent article in the journal Nature.

    “In order to successfully model a star with asteroseismology, one needs to make the model as realistic as possible,” Green says. “This means that the values for a large number of different parameters must be specified: the total mass and radius of the star, the atmospheric temperature, the thickness and composition of the atmosphere and, in the case of a white dwarf like this one, whose interior is stratified in layers of different elements, the mass, thickness and composition of each interior layer.”

    In the process of modeling the interiors of stars, theoreticians first construct a range of theoretical stellar models covering all the possible values of every unknown parameter, and determine what pulsational frequencies would be excited in each one. Then they compare the resulting sets of model frequencies to the observed frequencies to see if there are any matches, and if so, which ones match the observations the best.

    “For stellar asteroseismology,” Green explains, “one of the best ways to prove that your models are realistic is to analyze a spectrum of the light from the star, determine its effective temperature and gravity, and show that these values agree with the temperature and gravity of the best asteroseismic model.”

    To do this, Green spent several nights pointing Steward’s Bok Telescope on Kitt Peak at the white dwarf KIC 08626021 — 1,376 light-years away in the constellation Cygnus. Using the telescope’s B&C spectrograph, she measured the amount of light that the star emits at different wavelengths, to obtain the so-called spectrum that her colleagues later analyzed to determine the actual atmospheric parameters of the dead star.

    Light Hits Arizona Mountaintop

    “Obtaining enough individual spectra to combine into a single useful spectrum was no small feat considering that this was a rather faint star for a telescope of this size,” Green says. “Nevertheless, we had enough time allocated to do the job properly. It would have been much more difficult to do with other, more powerful telescopes and instruments elsewhere, which have much more intense competition for observing time.”

    Green’s observations helped clear up a mystery that resulted in the proper classification of KIC 08626021. Her spectrum was the first to show convincingly that this white dwarf’s atmosphere was not composed entirely of helium, but contained significant traces of hydrogen as well. “Since hydrogen has a large effect on the opacity of the atmosphere, the slightly different atmospheric composition resulted in a higher calculated effective temperature for the star, consistent with its relatively rapid pulsations,” she says.

    The best-fitting asteroseismic solution not only matched the pulsational frequencies observed by the Kepler satellite “beautifully,” according to Green, “but now it also agreed extremely well with the temperature and gravity determined from the Bok Telescope spectrum.”

    Peeling back the different layers of the white dwarf revealed that the stellar core of these stars is bigger and richer in oxygen than predicted, and provided clues to all the main chemical elements present. In addition, a precise knowledge of the internal chemical composition of white dwarfs also is useful as a “cosmological chronometer” allowing astronomers to determine the ages of the various stellar populations of our galaxy.

    “To me, the most exciting part about this study is that we now have ‘observed’ values for things like the core size and oxygen abundance at the very center of a star that is nearing the end of its stellar life,” Green says. “It’s almost like real X-ray vision. These new results will be used to refine our knowledge of physical processes that take place in extreme conditions in the interiors of nearly all stars.”

    The study, “A large oxygen-dominated core from the seismic cartography of a pulsating white dwarf,” was led by Noemi Giammichele at the Institut de Recherche en Astrophysique et Planétologie (IRAP) of Toulouse, France.

    See the full article here .

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    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium? An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

  • richardmitnick 3:36 pm on January 2, 2018 Permalink | Reply
    Tags: 16 Cyg A and 16 Cyg B, A deep look into the hearts of stars, Asteroseismology, , , , , Inverse method-derived the local properties of the stellar interior from the observed frequencies,   

    From Max Planck Institute for Solar System Research: “A deep look into the hearts of stars” 

    Max Planck Institute for Solar System Research

    January 02, 2018

    Dr. Birgit Krummheuer
    Press and Public Relations
    Max Planck Institute for Solar System Research, Göttingen
    +49 551 384979-462

    Earl Bellinger
    Max Planck Institute for Solar System Research, Göttingen
    +49 551 384979-518

    Dr. Saskia Hekker
    Max Planck Institute for Solar System Research, Göttingen
    +49 551 384979-264

    Researchers measure the inner structure of distant suns from their pulsations

    A glimpse into the heart: Artist’s impression of the interior of the star, which was studied through its surface oscillations.
    © Earl Bellinger / ESA

    At first glance, it would seem to be impossible to look inside a star. An international team of astronomers, under the leadership of Earl Bellinger and Saskia Hekker of the Max Planck Institute for Solar System Research in Göttingen, has, for the first time, determined the deep inner structure of two stars based on their oscillations.

    Our Sun, and most other stars, experience pulsations that spread through the star’s interior as sound waves. The frequencies of these waves are imprinted on the light of the star, and can be later seen by astronomers here on Earth. Similar to how seismologists decipher the inner structure of our planet by analyzing earthquakes, astronomers determine the properties of stars from their pulsations—a field called asteroseismology. Now, for the first time, a detailed analysis of these pulsations has enabled Earl Bellinger, Saskia Hekker and their colleagues to measure the internal structure of two distant stars.

    The two stars they analyzed are part of the 16 Cygni system (known as 16 Cyg A and 16 Cyg B) and both are very similar to our own Sun.


    “Due to their small distance of only 70 light years, these stars are relatively bright and thus ideally suited for our analysis,” says lead author Earl Bellinger [The Astrophysical Journal]. “Previously, it was only possible to make models of the stars’ interiors. Now we can measure them.”

    To make a model of a star’s interior, astrophysicists vary stellar evolution models until one of them fits to the observed frequency spectrum. However, the pulsations of the theoretical models often differ from those of the stars, most likely due to some stellar physics still being unknown.

    Bellinger and Hekker therefore decided to use the inverse method. Here, they derived the local properties of the stellar interior from the observed frequencies. This method depends less on theoretical assumptions, but it requires excellent measurement data quality and is mathematically challenging.

    Using the inverse method, the researchers looked more than 500,000 km deep into the stars—and found that the speed of sound in the central regions is greater than predicted by the models. “In the case of 16 Cyg B, these differences can be explained by correcting what we thought to be the mass and the size of the star,” says Bellinger. In the case of 16 Cyg A, however, the cause of the discrepancies could not be identified.

    It is possible that as-yet unknown physical phenomena are not sufficiently taken into account by the current evolutionary models. “Elements that were created in the early phases of the star’s evolution may have been transported from the core of the star to its outer layers,” explains Bellinger. “This would change the internal stratification of the star, which then affects how it oscillates.”

    This first structural analysis of the two stars will be followed by more. “Ten to twenty additional stars suitable for such an analysis can be found in the data from the Kepler Space Telescope,” says Saskia Hekker, who leads the Stellar Ages and Galactic Evolution (SAGE) Research Group at the Max Planck Institute in Göttingen. In the future, NASA’s TESS mission (Transiting Exoplanet Survey Satellite) and the PLATO (Planetary Transits and Oscillation of Stars) space telescope planned by the European Space Agency (ESA) will collect even more data for this research field.

    NASA/Kepler Telescope



    The inverse method delivers new insights that will help to improve our understanding of the physics that happens in stars. This will lead to better stellar models, which will then improve our ability to predict the future evolution of the Sun and other stars in our Galaxy.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Max Planck Institute for Solar System Research

    The Max Planck Institute for Solar System Research has had an eventful history – with several moves, changes of name, and structural developments. The first prototype of the current institute was founded in 1934 in Mecklenburg; it moved to Katlenburg-Lindau in 1946. Not just the location of the buildings changed – the topic of research also moved, from Earth to outer space. In the first decades the focus of research was the stratosphere and ionosphere of the Earth, but since 1997 the institute exclusively researches the physics of planets and the Sun. In January 2014 the Max Planck Institute for Solar System Research has relocated to it’s new home: a new building in Göttingen close to the Northern Campus of the University of Göttingen.

  • richardmitnick 11:03 am on February 20, 2017 Permalink | Reply
    Tags: Asteroseismology, , , , , , , The Sun In A Distant Mirror   

    From astrobites: “The Sun In A Distant Mirror” 

    Astrobites bloc


    Title: A Distant Mirror: Solar Oscillations Observed on Neptune by the Kepler K2 Mission
    Authors: P. Gaulme et al.
    First Author’s Institution: Department of Astronomy, New Mexico State University
    Status: Published in The Astrophysical Journal Letters, open access

    Figure 1: Snapshot of the line-of-sight velocity variations on the Sun’s surface, measured from the Doppler shift of atmospheric absorption lines. (Image: GONG/NSO/AURA/NSF)

    How can we learn what lies beneath the surface of a star? One approach, called asteroseismology, is to study a star’s vibrations to infer its internal structure. The inside structure of the Sun in particular can be studied in great detail, because its vibrations are actually apparent on its surface (Fig. 1, see also: Helioseismology): The visible pattern of surface quivers shows the imprint of global acoustic oscillations, which are caused by resonant waves traveling through the Sun on peculiar paths, probing various depths. The same must be happening in faraway stars, yet due to their distance only the variability of their overall properties can be measured, for instance changes in brightness or temperature, which are however similarly caused by the stars’ intrinsic oscillations.

    An impressive instrument that has been built specifically to measure the brightness of stars with extreme precision over time is the Kepler space telescope.

    NASA/Kepler Telescope
    NASA/Kepler Telescope

    Its primary aim is to detect the transits of exoplanets, but its features make it suitable for asteroseismology as well. The authors of today’s paper investigate how Kepler would see a Sun-like star from far away, by pointing it at Neptune.


    The key idea of the paper is to determine the oscillation characteristics of the Sun by analyzing the intensity variations of the sunlight reflected by Neptune. This kind of measurement would allow a novel check of the calibration of widely used scaling relations, by observing the reference star – the Sun – with the same instrument as the actual target stars. These scaling relations are equations that connect the measurable (asteroseismic) quantities with the fundamental stellar properties, for example mass and radius.

    The main parameters of interest are the oscillation frequency of the Sun at maximum amplitude (\nu_{max}), which corresponds to the dominant “5-minute oscillation”, and the mean frequency separation between overtones (\Delta\nu), which are weaker oscillations that are also excited. The paper’s authors split up into seven teams to independently measure these parameters, all using slightly different methods of analysis. The underlying data, namely the light curve and its power spectrum (a decomposition of the light curve into frequency components), are treated just like the data of any other Kepler target (Fig. 2).

    Figure 2: Left: The full Neptune light curve taken with Kepler, showing the intensity variations of the reflected sunlight over 49 days in 1 minute intervals. Right: The gray and black lines are the raw and smoothed power spectrum of the Neptune light curve. The solid red line is the best-fit model, which includes several noise components indicated by the dashed red lines. The main signal due to the 5-minute oscillations of the Sun appears at the bottom right of the plot, around 3100 μHz. For comparison, the green line shows simultaneous VIRGO data (see text). The blue peaks are caused by Neptune’s rotation. (Figure 1 from the paper.)


    Surprisingly, all teams consistently overestimate the mass and radius of the Sun significantly by about 14% and 4%, assuming the standard solar reference values. However, this discrepancy can be explained by comparison with another, simultaneous light curve that was taken with the dedicated Sun-observing instrument VIRGO (on board the SOHO satellite).


    The true value of \nu_{max} was larger than usual during the time of observations, simply due to the random nature of the Sun’s oscillations.

    In addition, the teams attempted to determine not just the frequency spacing, but also the heights and widths of the individual overtones (“peak-bagging”), to create a complete model of the observed oscillation spectrum. The results are rather uncertain due to noise, but the findings of the teams are generally consistent, and they agree well with the VIRGO measurements, after differences in the technical design have been taken into account (e.g. different bandpasses).

    The successful indirect detection of the Sun’s acoustic oscillations in intensity measurements, with Neptune as “a distant mirror”, is a marvelous technological achievement. Not only that, but the lessons learned from this experiment will help further explore the limits of high-precision asteroseismology with Kepler.

    See the full article here .

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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.

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