NSF NOIRLab Launches 88 Constellations Project

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All-sky photo of the night sky (annotated)

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All-sky photo of the night sky

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Andromeda

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Andromeda (Annotated)

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Andromeda

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New web pages dedicated to mapping our night sky and exploring its wonders

NSF NOIRLab is launching the 88 Constellations project — a collection of free, high resolution, downloadable images of all 88 western IAU-recognized constellations. The project also includes the release of the largest open-source, freely available all-sky photo of the night sky.

oday NSF NOIRLab, funded by the U.S. National Science Foundation, in collaboration with ESA/Hubble, is releasing the 88 Constellations project. This complete collection of free, high resolution, downloadable images of all 88 western IAU-recognized constellations serves as an educational archive that can be used on the individual and scholastic levels. The project also includes the release of the largest open-source, freely available all-sky photo of the night sky.

The photographer behind this collection of stunning, high-quality images is German astrophotographer Eckhard Slawik. The images were taken on film and each panel comprises two separate exposures, one with and one without a diffuser filter to allow the stars’ colors to shine through.

All products include a comprehensive description of the constellation and its historic origins, as well as the corresponding standardized stick figure, outline drawing, finder chart and description of the constellation’s most prominent deep-sky objects. Existing astronomical images of such deep-sky objects, captured with various NSF NOIRLab telescopes, are also included. Downloadable flash cards and other audiovisual and educational materials make it easy to bring the constellations into the classrooms.

Also being released today is the largest open-source, freely available all-sky photo of the night sky. With 40,000 pixels, this is arguably one of the best such images ever made. The colossal sky-scape was compiled using images taken by Slawik from the best and darkest locations around the globe: Germany (Waldenburg), Spain (Tenerife, La Palma), Namibia and Chile.

The 88 Constellations images are open for exploration by all ages, and are especially suitable for use in planetariums and museums. Visit the project webpage to become familiar with all 88 constellations and see how many you can spot in your night sky.

Source: NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab)/News

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More information

NSF NOIRLab, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. 

The scientific community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence of I’oligam Du’ag- to the Tohono O’odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community.

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Links

• 88 Constellations
• Check out other NOIRLab Organization Releases

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Contacts

Josie Fenske
Jr. Public Information Officer
NSF NOIRLab
Email: josie.fenske@noirlab.edu

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Scientists capture most-detailed radio image of Andromeda galaxy to date

Radio image of Andromeda galaxy at 6.6 GHz (inset), captured using the Sardinia Radio Telescope in Italy

Credit: S. Fatigoni et al. (2021)

‘Disk of galaxy’ identified as region where new stars are born

Scientists have published a new, detailed radio image of the Andromeda galaxy – the Milky Way’s sister galaxy – which will allow them to identify and study the regions of Andromeda where new stars are born.

The study – which is the first to create a radio image of Andromeda at the microwave frequency of 6.6 GHz – was led by University of British Columbia physicist Sofia Fatigoni, with colleagues at Sapienza University of Rome and the Italian National Institute of Astrophysics. It was published online in Astronomy and Astrophysics.

“This image will allow us to study the structure of Andromeda and its content in more detail than has ever been possible,” said Fatigoni, a PhD student in the department of physics and astronomy at UBC. “Understanding the nature of physical processes that take place inside Andromeda allows us to understand what happens in our own galaxy more clearly – as if we were looking at ourselves from the outside.”

Prior to this study, no maps capturing such a large region of the sky around the Andromeda Galaxy had ever been made in the microwave band frequencies between one GHz to 22 GHz. In this range, the galaxy’s emission is very faint, making it hard to see its structure. However, it is only in this frequency range that particular features are visible, so having a map at this particular frequency is crucial to understanding which physical processes are happening inside Andromeda.

In order to observe Andromeda at this frequency, the researchers required a single-dish radio telescope with a large effective area. For the study, the scientists turned to the Sardinia Radio Telescope, a 64-metre fully steerable telescope capable of operating at high radio frequencies, located in Italy.

The Sardinia Radio Telescope, located in Sardinia, Italy

Credit: S. Fatigoni et al (2021)

It took 66 hours of observation and consistent data analysis for the researchers to map the galaxy with high sensitivity.

They were then able to estimate the rate of star formation within Andromeda, and produce a detailed map that highlighted the ‘disk of the galaxy,’ as the region where new stars are born.

“By combining this new image with those previously acquired, we have made significant steps forward in clarifying the nature of Andromeda’s microwave emissions and allowing us to distinguish physical processes that occur in different regions of the galaxy,” said Dr. Elia Battistelli, a professor in the department of physics at Sapienza and coordinator of the study.

“In particular, we were able to determine the fraction of emissions due to thermal processes related to the early stations of new star formation, and the fraction of radio signals attributable to non-thermal mechanisms due to cosmic rays that spiral in the magnetic field present in the interstellar medium,” Fatigoni said.

Final image of the Andromeda galaxy after averaging over the whole bandwidth at 6.6 GHz

Credit: S. Fatigoni et al (2021)

For the study, the team also developed and implemented software that allowed them to test new algorithms to identify never-before-examined lower emission sources in the field of view around Andromeda at a frequency of 6.6 GHz.

From the resulting map, researchers were able to identify a catalog of about 100 ‘point sources’ including stars, galaxies and other objects in the background of Andromeda.

Interview language(s): English, Italian

Note for reporters: Sofia Fatigoni is based in Rome, Italy and is available for interviews until 3 p.m. PST.

Contact: 

Sachintha Wickramasinghe
UBC Media Relations
Tel: 604-822-4636
Cel: 604-754-8289
Email: sachi.wickramasinghe@ubc.ca

Source:  University of British Columbia - UBC/News

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Andromeda's Bright X-Ray Mystery Solved by NuSTAR

NASA's Nuclear Spectroscope Telescope Array, or NuSTAR, has identified a candidate pulsar in Andromeda -- the nearest large galaxy to the Milky Way. This likely pulsar is brighter at high energies than the Andromeda galaxy's entire black hole population. Image credit: NASA/JPL-Caltech/GSFC/JHU .  › Full image and caption

The Milky Way's close neighbor, Andromeda, features a dominant source of high-energy X-ray emission, but its identity was mysterious until now. As reported in a new study, NASA's NuSTAR (Nuclear Spectroscopic Telescope Array) mission has pinpointed an object responsible for this high-energy radiation. 

The object, called Swift J0042.6+4112, is a possible pulsar, the dense remnant of a dead star that is highly magnetized and spinning, researchers say. This interpretation is based on its emission in high-energy X-rays, which NuSTAR is uniquely capable of measuring. The object's spectrum is very similar to known pulsars in the Milky Way.

It is likely in a binary system, in which material from a stellar companion gets pulled onto the pulsar, spewing high-energy radiation as the material heats up. 

"We didn't know what it was until we looked at it with NuSTAR," said Mihoko Yukita, lead author of a study about the object, based at Johns Hopkins University in Baltimore. The study is published in The Astrophysical Journal.

This candidate pulsar is shown as a blue dot in a NuSTAR X-ray image of Andromeda (also called M31), where the color blue is chosen to represent the highest-energy X-rays. It appears brighter in high-energy X-rays than anything else in the galaxy. 

The study brings together many different observations of the object from various spacecraft. In 2013, NASA's Swift satellite reported it as a high-energy source, but its classification was unknown, as there are many objects emitting low energy X-rays in the region. The lower-energy X-ray emission from the object turns out to be a source first identified in the 1970s by NASA's Einstein Observatory. 

Other spacecraft, such as NASA's Chandra X-ray Observatory and ESA's XMM-Newton had also detected it. However, it wasn't until the new study by NuSTAR, aided by supporting Swift satellite data, that researchers realized it was the same object as this likely pulsar that dominates the high energy X-ray light of Andromeda.

Traditionally, astronomers have thought that actively feeding black holes, which are more massive than pulsars, usually dominate the high-energy X-ray light in galaxies. As gas spirals closer and closer to the black hole in a structure called an accretion disk, this material gets heated to extremely high temperatures and gives off high-energy radiation. This pulsar, which has a lower mass than any of Andromeda's black holes, is brighter at high energies than the galaxy's entire black hole population.

Even the supermassive black hole in the center of Andromeda does not have significant high-energy X-ray emission associated with it. It is unexpected that a single pulsar would instead be dominating the galaxy in high-energy X-ray light.

"NuSTAR has made us realize the general importance of pulsar systems as X-ray-emitting components of galaxies, and the possibility that the high energy X-ray light of Andromeda is dominated by a single pulsar system only adds to this emerging picture," said Ann Hornschemeier, co-author of the study and based at NASA's Goddard Space Flight Center, Greenbelt, Maryland.

Andromeda is a spiral galaxy slightly larger than the Milky Way. It resides 2.5 million light-years from our own galaxy, which is considered very close, given the broader scale of the universe. Stargazers can see Andromeda without a telescope on dark, clear nights. 

"Since we can't get outside our galaxy and study it in an unbiased way, Andromeda is the closest thing we have to looking in a mirror," Hornschemeier said.

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR's mission operations center is at UC Berkeley, and the official data archive is at NASA's High Energy Astrophysics Science Archive Research Center. ASI provides the mission's ground station and a mirror archive. JPL is managed by Caltech for NASA.

For more information on NuSTAR, visit: http://www.nasa.gov/nustar - http://www.nustar.caltech.edu

News Media Contact

Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6425
elizabeth.landau@jpl.nasa.gov

Source: JPL-Caltech

What happens when Cosmic Giants meet Galactic Dwarfs?

Cosmic Giants Meet Galactic Dwarfs in GAMA

 A still from the animation available on Dropbox

 Animation movie

When two different sized galaxies smash together, the larger galaxy stops the smaller one making new stars, according to a study of more than 20,000 merging galaxies.

The research, published today, also found that when two galaxies of the same size collide, both galaxies produce stars at a much faster rate.

Astrophysicist Luke Davies, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), says our nearest major galactic neighbour, Andromeda, is hurtling on a collision course with the Milky Way at about 400,000 kilometres per hour.

“Don’t panic yet, the two won’t smash into each other for another four billion years or so,” he says.

“But investigating such cosmic collisions lets us better understand how galaxies grow and evolve.”

Previously, astronomers thought that when two galaxies smash into each other their gas clouds—where stars are born—get churned up and seed the birth of new stars much faster than if they remained separate.

However Dr Davies’ research, using the Galaxy and Mass Assembly (GAMA) survey observed using the Anglo-Australian Telescope in regional New South Wales, suggests this idea is too simplistic.

He says whether a galaxy forms stars more rapidly in a collision, or forms any new stars at all, depends on if it is the big guy or the little guy in this galactic car crash.

“When two galaxies of similar mass collide, they both increase their stellar birth rate,” Dr Davies says.

“However when one galaxy significantly outweighs the other, we have found that star formation rates are affected for both, just in different ways."

“The more massive galaxy begins rapidly forming new stars, whereas the smaller galaxy suddenly struggles to make any at all."

“This might be because the bigger galaxy strips away its smaller companion’s gas, leaving it without star-forming fuel or because it stops the smaller galaxy obtaining the new gas required to form more stars.”

The study was released today in the journal Monthly Notices of the Royal Astronomical Society, published by Oxford University Press.

So what will happen in four billion years to the Milky Way and Andromeda?

Dr Davies says the pair are like “cosmic tanks”—both relatively large and with similar mass.

“As they get closer together they will begin to affect each other’s star formation, and will continue to do so until they eventually merge to become a new galaxy, which some call ‘Milkdromeda’,” he says.

Further information:

ICRAR is a joint venture between Curtin University and The University of Western Australia with support and funding from the State Government of Western Australia.

Original publication details:

‘Galaxy and Mass Assembly (GAMA): the effect of close interactions on star formation in galaxies’ in the Monthly Notices of the Royal Astronomical Society. Published online on 13/7/2015 at: http://mnras.oxfordjournals.org/lookup/doi/10.1093/mnras/stv1241

Imagens and Animation:

All images and an animation are available in various resolutions on Dropbox.

Contacts:

Dr Luke Davies
ICRAR – UWA (Perth, GMT +8:00)
Ph: +61 8 6488 7750
M: +61 466 277 672
E: luke.davies@icrar.org

Pete Wheeler
Media Contact, ICRAR (Perth, GMT +8:00)
Ph: +61 8 6488 7758
M: +61 423 982 018
E: pete.wheeler@icrar.org

UWA Media Office
Ph: +61 8 6488 7977

Source:  International Centre of Astronomy Research (ICRAR)

Monster galaxies gain weight by eating smaller neighbours

Some of the many thousands of merging galaxies identified within the GAMA survey.
Credit: Professor Simon Driver and Dr Aaron Robotham, ICRAR. Hi-res image

Andromeda and the Milky Way Collide! from ICRAR on Vimeo

In about five billion years time, nearby massive galaxy Andromeda will merge with our own galaxy, the Milky Way, in an act of gallactic cannibalism (technically Andromeda will be eating us, as it's the bigger of the two galaxies.). There haven't been any large mergers with our galaxy recently, but we can see the remnants of galaxies that have previously been snacked on by the Milky Way. We're also going to eat two nearby dwarf galaxies, the Large and Small Magellanic Clouds sometime in the future. This simulation shows what will happen when the Milky Way and Andromeda get closer together and then collide, and then finally come together once more to merge into an even bigger galaxy. Simulation Credit: Prof Chris power (ICRAR-UWA), Dr Alex Hobbs (ETH Zurich), Prof Justin Reid (University of Surrey), Dr Dave Cole (University of Central Lancashire) and the Theoretical Astrophysics Group at the University of Leicester.Video Production Credit: Pete Wheeler, ICRAR.

Dr Aaron Robotham

Credit: Joe Liske

Massive galaxies in the Universe have stopped making their own stars and are instead snacking on nearby galaxies, according to research by Australian scientists.

Astronomers looked at more than 22,000 galaxies and found that while smaller galaxies were very efficient at creating stars from gas, the most massive galaxies were much less efficient at star formation, producing hardly any new stars themselves, and instead grew by eating other galaxies.

The study was released today in the journal Monthly Notices of the Royal Astronomical Society, published by Oxford University Press.

Dr Aaron Robotham based at The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said smaller ‘dwarf’ galaxies were being eaten by their larger counterparts.

“All galaxies start off small and grow by collecting gas and quite efficiently turning it into stars,” he said.

“Then every now and then they get completely cannibalised by some much larger galaxy.”

Dr Robotham, who led the research, said our own Milky Way was at a tipping point and expected to now grow mainly by eating smaller galaxies, rather than by collecting gas.

“The Milky Way hasn’t merged with another large galaxy for a long time but you can still see remnants of all the old galaxies we’ve cannibalised,” he said.

“We’re also going to eat two nearby dwarf galaxies, the Large and Small Magellanic Clouds, in about four billion years.”But Dr Robotham said the Milky Way would eventually get its comeuppance when it merged with the nearby Andromeda Galaxy in about five billion years.

“Technically, Andromeda will eat us because it’s the more massive one,” he said.

Almost all of the data for the research was collected with the Anglo-Australian Telescope in New South Wales as part of the Galaxy And Mass Assembly (GAMA) survey, led by Professor Simon Driver at ICRAR.

The GAMA survey involves more than 90 scientists and took seven years to complete.

This study is one of more than 60 publications to have come from the work, with another 180 in progress.

Dr Robotham said as galaxies grew they had more gravity and could therefore more easily pull in their neighbours.

He said the reason star formation slowed down in really massive galaxies was thought to be because of extreme feedback events in a very bright region at the centre of a galaxy known as an active galactic nucleus.

“The topic is much debated, but a popular mechanism is where the active galactic nucleus basically cooks the gas and prevents it from cooling down to form stars,” Dr Robotham said.

Ultimately, gravity is expected to cause all the galaxies in bound groups and clusters to merge into a few super-giant galaxies, although we will have to wait many billions of years before that happens.

“If you waited a really, really, really long time that would eventually happen but by really long I mean many times the age of the Universe so far,” Dr Robotham said.

Further Information

ICRAR is a joint venture between Curtin University and The University of Western Australia with support and funding from the State Government of Western Australia.


Original publication details

‘Galaxy and Mass Assembly (GAMA): Galaxy close-pairs, mergers and the future fate of stellar mass’ in the Monthly Notices of the Royal Astronomical Society. Published online 19/9/2014 at: http://mnras.oxfordjournals.org/lookup/doi/10.1093/mnras/stu1604

Preprint version accessible at: http://arxiv.org/abs/1408.1476

 
Contacts
 
Dr Aaron Robotham
ICRAR – UWA (Currently travelling in South Africa, GMT +2:00)
E: aaron.robotham@icrar.org

Professor Simon Driver
Principal Investigator of the GAMA project. ICRAR – UWA (Perth, GMT +8:00)
Ph: +61 8 6488 7747    M: +61 400 713 514     
E: simon.driver@icrar.org

Kirsten Gottschalk
Media Contact, ICRAR (Perth, GMT +8:00)
Ph: +61 8 6488 7771     M: +61 438 361 876     
E: kirsten.gottschalk@icrar.org

UWA Media Office
Ph: +61 8 6488 7977

Source:  Internacional Centre for Radio Astronomy Research (ICRAR)

Milky Way amidst a ‘Council of Giants’

We live in a galaxy known as the Milky Way – a vast conglomeration of 300 billion stars, planets whizzing around them, and clouds of gas and dust floating in between. Though it has long been known that the Milky Way and its orbiting companion Andromeda are the dominant members of a small group of galaxies, the Local Group, which is about 3 million light years across, much less was known about our immediate neighbourhood in the universe. Now, a new paper by York University Physics & Astronomy Professor Marshall McCall, published today in the journal Monthly Notices of the Royal Astronomical Society, maps out bright galaxies within 35-million light years of the Earth, offering up an expanded picture of what lies beyond our doorstep.

A diagram showing the brightest galaxies within 20 million light years of the Milky Way, as seen from above. The largest galaxies, here shown in yellow at different points around the dotted line, make up the ‘Council of Giants’. Credit: Marshall McCall / York University. Click here for a full-size image

“All bright galaxies within 20 million light years, including us, are organized in a ‘Local Sheet’ 34-million light years across and only 1.5-million light years thick,” says McCall. “The Milky Way and Andromeda are encircled by twelve large galaxies arranged in a ring about 24-million light years across – this ‘Council of Giants’ stands in gravitational judgment of the Local Group by restricting its range of influence.”

A diagram showing the brightest galaxies within 20 million light years of the Milky Way, this time viewed from the side. Credit: Marshall McCall / York University. Click here for a full-size image 

McCall says twelve of the fourteen giants in the Local Sheet, including the Milky Way and Andromeda, are "spiral galaxies" which have highly flattened disks in which stars are forming.  The remaining two are more puffy "elliptical galaxies", whose stellar bulks were laid down long ago.  Intriguingly, the two ellipticals sit on opposite sides of the Council.  Winds expelled in the earliest phases of their development might have shepherded gas towards the Local Group, thereby helping to build the disks of the Milky Way and Andromeda.

McCall also examined how galaxies in the Council are spinning. He comments: “Thinking of a galaxy as a screw in a piece of wood, the direction of spin can be described as the direction the screw would move (in or out) if it were turned the same way as the galaxy rotates. Unexpectedly, the spin directions of Council giants are arranged around a small circle on the sky.  This unusual alignment might have been set up by gravitational torques imposed by the Milky Way and Andromeda when the universe was smaller.”

The boundary defined by the Council has led to insights about the conditions which led to the formation of the Milky Way.  Most important, only a very small enhancement in the density of matter in the universe appears to have been required to produce the Local Group.  To arrive at such an orderly arrangement as the Local Sheet and its Council, it seems that nearby galaxies must have developed within a pre-existing sheet-like foundation comprised primarily of dark matter.

“Recent surveys of the more distant universe have revealed that galaxies lie in sheets and filaments with large regions of empty space called voids in between,” says McCall. “The geometry is like that of a sponge.  What the new map reveals is that structure akin to that seen on large scales extends down to the smallest.”

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Media Contacts

Robin Heron
Media Relations
York University
Canada
Tel: +1 416 736 2100 x22097
rheron@yorku.ca

Robert Massey
Royal Astronomical Society
Tel: +44 (0)20 7734 3307 x214
Mob: +44 (0)794 124 8035
rm@ras.org.uk

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Animation

 This movie illustrates the positions of the nearby galaxies, including those in the ‘Council of Giants’, in three dimensions. Credit: Marshall McCall / York University

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Further information

The new work appears in “A Council of Giants”, M. L. McCall, Monthly Notices of the Royal Astronomical Society, Oxford University Press, in press.

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Notes for editors

York University is helping to shape the global thinkers and thinking that will define tomorrow. York U’s unwavering commitment to excellence reflects a rich diversity of perspectives and a strong sense of social responsibility that sets us apart. A York U degree empowers graduates to thrive in the world and achieve their life goals through a rigorous academic foundation balanced by real-world experiential education. As a globally recognized research centre, York U is fully engaged in the critical discussions that lead to innovative solutions to the most pressing local and global social challenges. York U’s 11 faculties and 27 research centres are thinking bigger, broader and more globally, partnering with 288 leading universities worldwide. 

York U's community is strong − 55,000 students, 7,000 faculty and staff, and more than 250,000 alumni.

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3800 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

Follow the RAS on Twitter

Source:  The Royal Astronomical Society (RAS)

Andromeda’s coat of many colours

Andromeda in multiple wavelengths
Link YouTube

ESA’s fleet of space telescopes has captured the nearby Andromeda Galaxy, also known as M31, in different wavelengths. Most of these wavelengths are invisible to the eye and each shows a different aspect of the galaxy’s nature.

Visible light, as seen by optical ground-based telescopes and our eyes, reveals the various stars that shine in the Andromeda Galaxy, yet it is just one small part of the full spectrum of electromagnetic radiation. There are many different wavelengths that are invisible to us but which are revealed by ESA’s orbiting telescopes.

Starting at the long wavelength end, the Planck spacecraft collects microwaves. These show up particles of incredibly cold dust, at just a few tens of degrees above absolute zero. Slightly higher temperature dust is revealed by the shorter, infrared wavelengths observed by the Herschel space telescope. This dust traces locations in the spiral arms of the Andromeda Galaxy where new stars are being born today.

The XMM-Newton telescope detects wavelengths shorter than visible light, collecting ultraviolet and X-rays. These show older stars, many nearing the end of their lives and others that have already exploded, sending shockwaves rolling through space. By monitoring the core of Andromeda since 2002, XMM-Newton has revealed many variable stars, some of which have undergone large stellar detonations known as novae.

Ultraviolet wavelengths also display the light from extremely massive stars. These are young stars that will not live long. They exhaust their nuclear fuel and explode as supernovae typically within a few tens of millions of years after they are born. The ultraviolet light is usually absorbed by dust and re-emitted as infrared, so the areas where ultraviolet light is seen directly correspond to relatively clear, dust-free parts of Andromeda.

By putting all of these observations together, and seeing Andromeda in its many different colours, astronomers are able to follow the life cycle of the stars.

Source: ESA

Isolating a thick disc in Andromeda

Schematic representation of a thick disc structure. The thick disc is formed of stars that are typically much older than those in the thin disc, making it an ideal probe of galactic evolution . Credit: Amanda Smith, IoA graphics officer

A team of astronomers from the UK, the US and Europe have identified a thick stellar disc in the nearby Andromeda galaxy for the first time. The discovery and properties of the thick disc will constrain the dominant physical processes involved in the formation and evolution of large spiral galaxies like our own Milky Way.

By analysing precise measurements of the velocities of individual bright stars within the Andromeda galaxy using the Keck telescope in Hawaii, the team have managed to separate out stars tracing out a thick disc from those comprising the thin disc, and assess how they differ in height, width and chemistry.

Optical image of The Andromeda galaxy (M31)
Credit: Robert Gendler

Spiral structure dominates the morphology of large galaxies at the present time, with roughly 70% of all stars contained in a flat stellar disc. The disc structure contains the spiral arms traced by regions of active star formation, and surrounds a central bulge of old stars at the core of the galaxy. “From observations of our own Milky Way and other nearby spirals, we know that these galaxies typically possess two stellar discs, both a ‘thin’ and a ‘thick’ disc,” explains the leader of the study, Michelle Collins, a PhD student at Cambridge’s Institute of Astronomy. The thick disc consists of older stars whose orbits take them along a path that extends both above and below the more regular thin disc. “The classical thin stellar discs that we typically see in Hubble imaging result from the accretion of gas towards the end of a galaxy’s formation, whereas thick discs are produced in a much earlier phase of the galaxy’s life, making them ideal tracers of the processes involved in galactic evolution.”

Currently, the formation process of the thick disc is not well understood. Previously, the best hope for comprehending this structure was by studying the thick disc of our own Galaxy, but much of this is obscured from our view. The discovery of a similar thick disk in Andromeda presents a much cleaner view of spiral structure. Andromeda is our nearest large spiral neighbour -- close enough to be visible to the unaided eye -- and can be seen in its entirety from the Milky Way. Astronomers will be able to determine the properties of the disk across the full extent of the galaxy and look for signatures of the events connected to its formation. It requires a huge amount of energy to stir up a galaxy's stars to form a thick disc component, and theoretical models proposed include accretion of smaller satellite galaxies, or more subtle and continuous heating of stars within the galaxy by spiral arms.

Ages and orientations of the stellar components of disc galaxies. The halo (or spheroid) contains the oldest populations, followed by the thick stellar disc. The thin disc typically contains the youngest generations of stars. Credit: RAVE collaboration

"Our initial study of this component already suggests that it is likely older than the thin disc, with a different chemical composition'' commented UCLA Astronomer, Mike Rich, "Future more detailed observations should enable us to unravel the formation of the disc system in Andromeda, with the potential to apply this understanding to the formation of spiral galaxies throughout the Universe.''

"This result is one of the most exciting to emerge from the larger parent survey of the motions and chemistry of stars in the outskirts of Andromeda,'' said fellow team member, Dr. Scott Chapman, also at the Institute of Astronomy. "Finding this thick disc has afforded us a unique and spectacular view of the formation of the Andromeda system, and will undoubtedly assist in our understanding of this complex process.''

This study was published in Monthly Notices of the Royal Astronomical Society (see the accepted paper) by Michelle Collins, Scott Chapman and Mike Irwin from the Institute of Astronomy, together with Rodrigo Ibata from L'Observatoire de Strasbourg, Mike Rich from University of California, Los Angeles, Annette Ferguson from the Institute for Astronomy in Edinburgh, Geraint Lewis from the University of Sydney, and Nial Tanvir and Andreas Koch from the University of Leicester.

This study is published in Monthly Notices of the Royal Astronomical Society:
http://arxiv.org/abs/1010.5276
http://www.ast.cam.ac.uk/~mlmc2/M31thickdisc.html

Andromeda Galaxy

The Andromeda Galaxy (aka M31)

Image Credit: ESA/Herschel/SPIRE/PACS/HELGA ;
ESA/XMM/EPIC/OM

Optical: Robert Gendler

Over the Christmas period of 2010, the Herschel and ESA's XMM-Newton satellite took images of our Galaxy’s nearest large neighbour, the Andromeda Galaxy. Galaxies such as our own Milky Way are often described as island Universes, containing hundreds of billions of stars and measuring tens or hundreds of thousands of light years across. But they are rarely completely isolated, and the Milky Way is accompanied by the Andromeda Galaxy. At a relatively close distance of 2.5 million light years, Andromeda is very similar in size to the Milky Way, and provides a way to study star formation on galaxy-wide scales in great detail.

Its proximity makes the Andromeda Galaxy (aka M31) appear very large in the sky, as wide as almost 6 full moons, and on a dark night the bright central core can sometimes even be seen with the naked eye. In optical light, the stars are seen to form spiral arms of stars, separated by dark dust lanes, all slightly tilted over from our point of view. Both the Herschel and XMM-Newton observatories reveal regions of star formation in the Andromeda Galaxy: Herschel observes in the far infrared, while XMM-Newton is sensitive to X-Rays.

While Herschel shows the cool and cold dust that shines because it is heated by the massive young stars that are forming within the dust clouds, XMM-Newton shows the endpoints of stellar evolution: on the one hand shock waves and ejected material in supernovae remnants, and on the other hand massive objects often in close binary systems. Professor Walter Gear, of Cardiff University, said "this image will allow us to study the global star formation in a galaxy remarkably similar to our own, but from the outside rather than with the limited view of our own galaxy we get from the inside".

Galaxies such as our own Milky Way are often described as island Universes, containing hundreds of billions of stars and measuring tens or hundreds of thousands of light years across. But they are rarely completely isolated, and the Milky Way is accompanied by the Andromeda Galaxy. At a relatively close distance of 2.5 million light years, Andromeda is very similar in size to the Milky Way, and provides a way to study star formation on galaxy-wide scales in great detail.

Its proximity makes the Andromeda Galaxy (aka M31) appear very large in the sky, as wide as almost 6 full moons, and on a dark night the bright central core can sometimes even be seen with the naked eye. In optical light, the stars are seen to form spiral arms of stars, separated by dark dust lanes, all slightly tilted over from our point of view. Both the Herschel and XMM-Newton observatories reveal regions of star formation in the Andromeda Galaxy: Herschel observes in the far infrared, while XMM-Newton is sensitive to X-Rays.

While Herschel shows the cool and cold dust that shines because it is heated by the massive young stars that are forming within the dust clouds, XMM-Newton shows the endpoints of stellar evolution: on the one hand shock waves and ejected material in supernovae remnants, and on the other hand massive objects often in close binary systems. Professor Walter Gear, of Cardiff University, said "this image will allow us to study the global star formation in a galaxy remarkably similar to our own, but from the outside rather than with the limited view of our own galaxy we get from the inside".

The Andromeda Galaxy is particularly interesting because, unlike other bright galaxies, it shows a large ring of dust that is about 75,000 light years across around the centre of the galaxy. Some astronomers speculate that this dust ring may have been formed in a recent collision with another galaxy. The Herschel image reveals intricate detail, with several rings of star-forming dust visible. Dr Jacopo Fritz, of Universiteit Ghent, leads the "HELGA" project which is using Herschel to observe the Andromeda Galaxy. He said "combining Herschel's high sensitivity and spatial resolution, together with the huge size of the sky region that we observed (about 50 times the area of the full moon), we will be able, for the first time ever, to dig into the characteristics of such structures at these wavelengths, possibly linking them to the very cold dust in the most remote outskirts of Andromeda".

XMM-Newton shows hundreds of x-ray sources within the galaxy, many of them clustered around the centre, where the stars are densest. The red sources in the x-ray image on the left are low-mass objects that emit only very low energy x-rays. Some of these sources are novae with a white dwarf star that gradually is accreting material from its larger companion. In these systems the white dwarf may eventually grow massive enough to collapse catastrophically and explode as a supernova. In contrast, the brighter, bluer x-ray sources are likely to be binary systems in which a neutron star or a black hole formed by the death of a star many times more massive than our Sun rotates around a normal star. For more composite images of the Andromeda Galaxy, click here or see the "annotated images" links below the main image above.

Using all three wavelength channels observed by the SPIRE instrument on Herschel, the temperature of the dust can be calculated. The dust ring is clearly visible as a bright white ring. The central regions of the galaxy appear bluer, indicating that the dust is slightly warmer, being heated by the intense light from the stars in the central bulge of the galaxy.

Both parts of the spectrum observed by Herschel and XMM-Newton are inaccessible from the ground, due to our atmosphere. Between the two images obtained by these two ESA space observatories we get a unique insight into the history of star formation in our galactic neighbour, from vigorous young stars in the process of formation, through to stars that have died, or are going to die a violent death. Professor Matt Griffin, of Cardiff University, and lead scientist of the SPIRE instrument, said "the superb three-colour SPIRE image shows us the big picture of star formation in spiral galaxies, and its striking combination with the X-ray image demonstrates the scientific power and beauty of space astronomy".

Swift Makes Best-ever Ultraviolet Portrait of Andromeda Galaxy

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This mosaic of M31 merges 330 individual images taken by the Ultraviolet/Optical Telescope aboard NASA's Swift spacecraft. It is the highest-resolution image of the galaxy ever recorded in the ultraviolet. The image shows a region 200,000 light-years wide and 100,000 light-years high (100 arcminutes by 50 arcminutes). Credit: NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)

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This optical view from a ground-based telescope shows the Andromeda Galaxy in a more familiar light. This image encompasses the same area as the Swift mosaic. Credit: Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF

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M31 lies 2.5 million light-years away in the constellation Andromeda and is the nearest large spiral galaxy to our own. Under a clear, dark sky, it can be seen as a misty patch with the naked eye. Credit: Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF

In a break from its usual task of searching for distant cosmic explosions, NASA's Swift satellite has acquired the highest-resolution view of a neighboring spiral galaxy ever attained in the ultraviolet. The galaxy, known as M31 in the constellation Andromeda, is the largest and closest spiral galaxy to our own.

"Swift reveals about 20,000 ultraviolet sources in M31, especially hot, young stars and dense star clusters," said Stefan Immler, a research scientist on the Swift team at NASA's Goddard Space Flight Center in Greenbelt, Md. "Of particular importance is that we have covered the galaxy in three ultraviolet filters. That will let us study M31's star-formation processes in much greater detail than previously possible."

M31, also known as the Andromeda Galaxy, is more than 220,000 light-years across and lies 2.5 million light-years away. On a clear, dark night, the galaxy is faintly visible as a misty patch to the naked eye.

Between May 25 and July 26, 2008, Swift's Ultraviolet/Optical Telescope (UVOT) acquired 330 images of M31 at wavelengths of 192.8, 224.6, and 260 nanometers. The images represent a total exposure time of 24 hours.

The task of assembling the resulting 85 gigabytes of images fell to Erin Grand, an undergraduate student at the University of Maryland at College Park who worked with Immler as an intern this summer. "After ten weeks of processing that immense amount of data, I'm extremely proud of this new view of M31," she said.

Several features are immediately apparent in the new mosaic. The first is the striking difference between the galaxy's central bulge and its spiral arms. "The bulge is smoother and redder because it's full of older and cooler stars," Immler explained. "Very few new stars form here because most of the materials needed to make them have been depleted."

Dense clusters of hot, young, blue stars sparkle beyond the central bulge. As in our own galaxy, M31's disk and spiral arms contain most of the gas and dust needed to produce new generations of stars. Star clusters are especially plentiful in an enormous ring about 150,000 light-years across.

What triggers the unusually intense star formation in Andromeda's "ring of fire"? Previous studies have shown that tides raised by the many small satellite galaxies in orbit around M31 help boost the interactions within gas clouds that result in new stars.

In 1885, an exploding star in M31's central bulge became bright enough to see with the naked eye. This was the first supernova ever recorded in any galaxy beyond our own Milky Way. "We expect an average of about one supernova per century in galaxies like M31," Immler said. "Perhaps we won't have to wait too long for another one."

"Swift is surveying nearby galaxies like M31 so astronomers can better understand star- formation conditions and relate them to conditions in the distant galaxies where we see gamma-ray bursts occurring," said Neil Gehrels, the mission's principal investigator at NASA Goddard. Since Swift's November 2005 launch, the satellite has detected more than 400 gamma-ray bursts -- massive, far-off explosions likely associated with the births of black holes.

Swift is managed by NASA Goddard. It was built and is being operated in collaboration with Pennsylvania State University, the Los Alamos National Laboratory in New Mexico, and General Dynamics of Gilbert, Ariz., in the United States. International collaborators include the University of Leicester and Mullard Space Sciences Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, and additional partners in Germany and Japan.

Related Link: Blueshift podcast: Swift sees Andromeda in a New Light

Francis Reddy
NASA's Goddard Space Flight Center

No strain for Andromeda: Galaxy is cosmic cannibal

This undated artist's rendering provided by the University of Cambridge, England, shows the spiral galaxy of Andromeda, center right, over a period of about three billion years as repeated, but modified views of the dwarf galaxy Triangulum, move away from it, clockwise towards Earth, then back towards it, where Triangulum will be ultimately devoured by the Andromeda galaxy says astronomer John Dubinski. (AP Photo/Illustration by John Dubinski and Larry Widrow)

The survey of the Andromeda Galaxy, which lies approximately 2.5million light years away, has revealed what seems to be evidence of the cosmic formation process absorbing some of its nearest neighbours.

An international team of astronomers, including scholars from the University of Cambridge, made the observations during an ongoing survey of Andromeda using the Canada-France-Hawaii telescope and its MegaCam/MegaPrime digital camera.

The study, which is the biggest of its kind, took in an area with a diameter equivalent to one million light years, enabling scientists to produce the broadest and deepest panoramic image of a galaxy ever made. The results will be published in the journal Nature on September 3rd.

Theory holds that galaxies evolve and grow by absorbing smaller galaxies over time. One way to test this is to find the leftovers from this process. Finding these faint structures is difficult, since it involves looking over an area hundreds of time larger than the main "disc" at the galaxy's centre.

The new study found streams and structures on the fringes of Andromeda which appear to be the leftovers from exactly this sort of process. It suggests that Andromeda has expanded by cannibalising other galaxies nearby, and that the process is still under way.

"This is a startling visual demonstration of the truly vast scale of galaxies," Dr Mike Irwin, from the University of Cambridge's Institute of Astronomy and one of the report's lead authors, said. "The survey has produced an unrivalled panorama of galaxy structure which reveals that galaxies are the result of an ongoing process of accretion and interaction with their neighbours."
Andromeda is the nearest large galaxy visible to the naked eye from the Northern Hemisphere. The researchers charted the unexplored outskirts of the galaxy for the first time, detecting stars and giant structures in the process.

Although these now form part of its furthest reaches, many of these stars could not have formed within Andromeda itself because the density of gas so far from the galaxy's core would have been too low to allow formation to take place. Therefore, the team reason that they are almost certainly the remnants of other, smaller galaxies which have been absorbed by Andromeda - and that Andromeda itself is still in a state of expansion.

On a similar basis, the paper argues that the larger-scale substructures identified on the galaxy's fringes are probably the "undigested" remains of previously accreted dwarf galaxies. In all likelihood, they originally belonged to dwarf galaxies or other, proto-galactic fragments.

The results also indicate that Andromeda is presently interacting with a nearby region called the Triangulum Galaxy, which is also visible in the Northern Hemisphere using a small telescope. "Ultimately, these two galaxies may end up merging completely," Dr Scott Chapman, Reader in Astrophysics at the Institute of Astronomy, University of Cambridge, said. "Ironically, galaxy formation and galaxy destruction seem to go hand in hand."

Source: http://www.physorg.com/

Provided by University of Cambridge