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Michigan Astronomer searches for the origins of organic molecules

Artist's concept of the Hershel Space Telescope When the Herschel space telescope launches later this month, it will carry with it an instrument that will be used by a professor here at Michigan.

Associate Professor Edwin Bergin is co-investigator on the Heterodyne Instrument for the Far Infrared (HIFI) carried on board the Herschel Space Telescope. Heterodyne spectrometers allow very complex analysis of light by mixing the incoming signal with a reference source, so astronomers can determine not only what wavelength the incoming light is, but also other information like the phase and amplitude. This instrument will cover 157-625 microns, which is in the far infra-red region of the electromagnetic spectrum. Water and several organic molecules emit light in this region. Also, Herschel’s instruments will be the first to study the far infra-red region of the spectrum, which opens up the possibility of discovering new molecules.

"We'll be studying the full extent of chemistry in space and we hope to learn what types of organics are out there as a function of their distance from a star," Bergin said.

Previously, astronomers have detected organic molecules in interstellar gas clouds, and have found organic molecules, including amino acids, inside of meteorites. According to Bergin, “that leads to the intriguing possibility that the chemistry ongoing in space and associated with the birth of our planet may have aided in the formation of life.”

A planet forming disk What astrobiologists really want to know is whether or not those molecules could have made it to a planet like Earth. With Herschel and HIFI, they will be able to look at the distribution of molecules in the disks around young stars where planets are forming. They hope this information will help answer questions about how these molecules originated on Earth. In particular, could complex organic molecules be present on a planet from the time of its formation, or do the molecules need to develop on the planet.

"The chemistry of space makes molecules that are the precursors of life. It's possible that the Earth didn't have to make these things on its own, but that they were provided from space,"

Professor Bergin is also part of a project to look for water in the planetary disks.
The current model for planet formation says Earth was too warm to have water when it formed, so the water on the surface now had to be brought to Earth via impacts from asteroids and comets. Observations with Herschel will help test if this is true.

Astronomy may not be able to answer the question of how life started on Earth, but it will help. However, answering the question of how much is out there and how it’s distributed could tell us something about life in the rest of the universe. “Maybe the stuff that made us is common throughout the universe, and hence maybe we’re not alone.”

Information and quotes for this article were taken from the UM News Service story at http://www.ns.umich.edu/htdocs/releases/story.php?id=7122 and the podcast, available from that page.
Additional information came from the Herschel website: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=16

Local Radio Observatory Important To Understanding Distant Galaxies

Two radio astronomers from Michigan have contributed to an international study of active galactic nuclei.

Mojave-fermi image

AGNs are galaxies whose cores emit more electromagnetic radiation than the rest of the galaxy. Many of these galaxies have radio jets, formed by a central massive black hole.

M87 image from Hubble Astronomers believe most galaxies have a massive black hole at their core. Massive black holes have strong magnetic fields, and charged particles can get caught in the magnetic field. If there is a lot of material falling into a black hole, some of if will get caught and flung out of the galaxy along the pole of the magnetic field. This results in two “beams” of charged particles that stream out from the center of the galaxy. The particles emit radio waves as they travel along the magnetic field, forming the radio jets.

Most AGNs also emit gamma-rays, and there has been a long debate about whether the gamma rays and radio waves are connected. A new paper led by Yuri Kovalev and co-authored by Professor Hugh Aller and research scientist Margo Aller indicates that they are indeed connected. It was published in the Astrophysical Journal Letters on May 1.

UMRAO Astronomers at the UM Radio Astronomy Observatory (UMRAO) participate in MOJAVE, a program for long term monitoring of active galaxies. Astronomers compared MOJAVE data to data collected by the Fermi Gamma Ray Space Telescope. What they found was a strong correlation between the gamma ray and radio observations. AGNs that are stronger radio sources are also stronger gamma ray emitters. The changes in emission occur on the same timescale for both types of radiation. Additionally, the source of radiation is a very compact region in the centers of the galaxies.

AGNs were much more common in the early universe, which means most of the ones we see now are very far away. The great distance makes them difficult to observe. It can be difficult to even tell what part of a galaxy the light is coming from.

According to Hugh Aller, "the findings help us begin to understand the physical processes going on in these remote active galactic nuclei, which have been very difficult to observe. These objects are a great mystery."

Paper:
http://www.iop.org/EJ/abstract/1538-4357/696/1/L17/
News story:
http://www.ns.umich.edu/htdocs/releases/story.php?id=7107
MOJAVE:
http://www.physics.purdue.edu/MOJAVE/
Fermi Space Telescope
http://fermi.gsfc.nasa.gov/
UMRAO
http://www.astro.lsa.umich.edu/obs/radiotel/index.php

Professor Fred Haddock dies

Emeritus Professor Fred T Haddock died Feb. 20 2009.

Professor Haddock was a pioneer in many ways. During the second World War, he helped develop a radar antenna that could be used inside a submarine periscope. After the war, he started in the field of Radio Astronomy, and was the first to discover thermal radiation from the Orion nebula, and radio bursts from solar flares. He joined the faculty at Michigan in 1956, where he designed and managed the construction of the radio telescope at Peach Mountain. Under his direction the telescope observed everything from the Sun to pulsars to quasars. He had a hand in many space exploration programs as well, including Apollo and the Voyager programs.

Professor Richard L. Sears dies

Emeritus Professor Richard Langley Sears died on Jan. 25 2009.

Dick joined the faculty of the University of Michigan in 1965. In the 40 years he spent with this department, he taught introductory astronomy to thousands of undergrads. Decades later, some of them still fondly remember his rather dry sense of humor and the unassuming manner in which he could slip the jokes into his lectures. He is the professor alumni are most likely to ask after.

In the wider astronomical community, he is best remembered for his work with Bahcall, Fowler and Iben, computing what came to be called the standard solar model, and was involved in computing neutrino emission from the sun very early in that field's development.

Dick got his undergraduate education at Harvard, and did his PhD thesis with Marshal Wrubel at Indiana. He held research positions at Indiana, Princeton, UC and Caltech before coming to Michigan.

He is survived by his wife Yvonne and daughter Amber.

Share your memories and read what others have to say at http://www.astro.lsa.umich.edu/donors/remember/Sears.php

Charles Steidel delivers 2009 Mohler Prize lecture “Witnessing the formation of galaxies: Violence in the young universe”

Charles Steidel will speak about observations of the early universe, and how that affects what we see in the universe today. Since light takes time to reach us, we see distant objects as they were long ago. The farthest objects we can see are so far away, we see them as they were 13 billion years ago. In his description of his talk, he says “… we can observe directly what the universe looked like up to about 13 billion years ago, and all times in between, up to the present. We now know that there was a particularly spectacular, and sometimes violent, period when the Universe was in its youth… where the process of galaxy formation was especially intense.”

Charles C. Steidel is the Lee A. DuBridge Professor of Astronomy at the California Institute of Technology. He received an A.B. from Princeton University and a Ph.D. in Astronomy from the California Institute of Technology. He has been a hubble Fellow at UC Berkeley, and was an Assistant Professor at MIT before moving to Caltech. He specializes in galaxy formation, and uses both large ground based and space based telescopes for his observations. He has received numerous awards, and was elected to the National Academy of Sciences in 2006. On Jan 23, he will receive the Orren C Mohler Prize.

Orren C. Mohler was a former department chair, and was director of the McMath-Hulbert Observatory in Lake Angelus Michigan. The Mohler prize was established in 1986 after his death. Three past Mohler prize recipients have gone on to win Nobel or Crafoord Prizes.

The 2009 Mohler Prize lecture is scheduled for Friday, January 23 at 7:30 PM in 1800 Chem. This is the first in the Distinguished Lecture Series, part of the Astronomy Theme Semester. Directions and links to maps are at http://uuis.umich.edu/cic/buildingproject/index.cfm?BuildingID=34. An open house at the Angell Hall Observatory follows the lecture.

More information and resources:

The Distinguished Lecture Series “Astronomy in the 21st Century”: http://lsa.umich.edu/universe/events.asp
More on the Mohler Prize: http://lsa.umich.edu/universe/mohler.asp
The Theme Semester website: http://lsa.umich.edu/universe
Open House schedule: http://astro.lsa.umich.edu/sas/openhouse.html

Galactic Russian Dolls Stop Star formation

Astronomers have long puzzled over why some elliptical galaxies stop forming many new stars, despite having the materials to do so. Now, an observation using NASA’s Chandra X-ray Observatory by a team of astronomers including assistant professor Mateusz Ruszkowski has an answer.

X-ray observations of galaxies show that many galaxies are surrounded by halos of hot gas. “For decades astronomers were puzzled by the presence of the warm gas around these objects. The gas was expected to cool down and form a lot of stars” said Prof. Ruszkowski in an interview with the UofM News Service.

M 84 x-ray image with circles indicating the location of bubbles The X-ray observation of M84, a giant elliptical galaxy in the Virgo cluster around 55 million light years away, show how the supermassive black hole at the center of the galaxy may be heating the gas. The image shows that the black hole has regular, repeated outbursts, which heats the gas in the halo. “Now, we see clear and direct evidence that the heating mechanism of black holes is persistent, producing enough heat to significantly suppress star formation. These plasma bubbles are caused by bursts of energy that happen one after another rather than occasionally, and the direct evidence for such periodic behavior is difficult to find.”

The image to the right is an x-ray image of M84, with red lines showing the location of the bubbles. Some of the bubbles are inside others, like a Russian matryoshka doll. In the X-ray image, the topmost bubble appears to be in the process of popping, releasing new superheated gas into the halo and the space between galaxies.

The team also produced a numerical simulation of the waves produced as the bubbles expand. The simulation shows that multiple outbursts can lead to the nested bubbles in the observation. Click the image at right to see the animation of the simulation.

The repeated outbursts pump energy into the gas and dust on the galaxy and between it and other galaxies. This prevents the gas from cooling enough to form new stars. The lead author of the paper in the astrophysical journal, Alexis Finoguenov, of UMBC and the Max-Planck Institute for Extraterrestrial Physics in Germany, compares the actions of the black hole to a human heart. “Just like our hearts periodically pump our circulatory systems to keep us alive, black holes give galaxies a vital warm component. They are a careful creation of nature, allowing a galaxy to maintain a fragile equilibrium.”

The paper “In-Depth Chandra Study of the AGN Feedback in Virgo Elliptical Galaxy M84” appears in The Astrophysical Journal, 686:911–917, 2008 October 20.
additional material for this articles comes from http://www.ns.umich.edu/htdocs/releases/story.php?id=6837 and
http://chandra.harvard.edu/photo/2008/m84/

Related stories:: UM astronomers help reveal origin of black hole jet.; New Movies Help Astronomers Understand Active Galactic Nuclei; Black Holes Light Up the Universe

Two Michigan Astronomers Selected to Help Guide New X-ray Observatory

Michigan Astronomy professors Joel Bregman and Jon Miller have been selected to serve on the Science Definition Team for the International X-ray Observatory (Formerly Constellation-X).

IXO will is a joint venture between the United States (NASA), Europe (ESA), and Japan (JAXA). It will study some of the most compelling ideas and problems in the universe, including the evolution of large-scale structure, the nature of space and time close to black holes, ultra-dense states of matter, feedback cycles, and the first quasars. Michigan is the only US institution to have two scientists on the team.

Visit the IXO website at http://ixo.gsfc.nasa.gov/

Installation of Dennison Mural Begins

Installation of the astronomy Chemed window mural began on September 26 with a line drawing of a radio telescope on the eastern-most windows (Click the images for a bigger version).

Over the next several weeks, Prof. Jim Cogswell will add several more images, ranging from equations to a gamma-ray image of the Milky Way. The images were provided by faculty in the astronomy department, based on their current projects and research.

The window mural is the first of many projects planned for the Winter ’09 Theme Semester and International Year of Astronomy.

Highlights of the department’s plans for the Theme Semester and IYA are available on our Events page: http://astro.lsa.umich.edu/about/events.php
The Theme Semester website is at http://www.lsa.umich.edu/universe/
Visit the International Year of Astronomy page at http://www.astronomy2009.org/

Astronomers Rediscover Young Supernova Remnant

One type of supernova occurs when a massive star dies: its outer layers collapse then bounce off the core causing a massive explosion. Normally, a supernova should occur roughly every 50 years in our galaxy. The last time a supernova was observed in our galaxy was Kepler’s supernova in 1604, and there are only a few dozen supernova remnants (SNRs) known to have occurred during all of human history. Astronomers have long believed the “missing” supernovas occurred in dusty regions that block the visible light.

When massive stars collapse, the outer layers expand away, forming the SNR. A typical SNR expands away from the center point in roughly spherical shells, so they have a roughly spherical shape. The core of the star is usually left behind, as a central compact object (CCR).

When astronomers first pointed their radio telescopes at G350.1-0.3 in the early 70s, the light coming from it indicated it might be a SNR. But radio observations in the mid-80s showed an irregular shape that didn't really look like a SNR (the white lines in the image at left). Many astronomers thought it was more likely a background galaxy, so it was downgraded to a SNR candidate and was even taken off many lists of SNRs. G350.1-0.3 was mostly forgotten.

Then in 2005, new data were published, which indicated that G350.1-0.3 had to be between 15 and 34.9 thousand light years away. Astronomically speaking, that’s practically on our back doorstep, and definitely in our own galaxy. There was no way this could be a background galaxy.

A team of astronomers, which included Jon Miller of UofM, led by Bryan Gaensler and Anant Tanna of the University of Sydney used the European Space Agency’s XMM-Newton X-ray observatory to look at G350.1-0.3, and reviewed some earlier radio observations. Their observations lead them to conclude that G350.1-0.3 is in fact a SNR.

The light coming from G350.1-0.3 indicates that it is exactly the kind of material you expect from a supernova caused by the collapse of a massive star. They found it is a mere 15 thousand light years away and is roughly 900 years old. The strange shape comes from the surrounding material. G350.1-0.3 is in a dense, dusty area of the galaxy, so the material did not expand evenly. It is so dusty in fact, that according to Gaensler “Even if you'd been looking straight at it when it exploded, it would've been invisible to the naked eye.”

Additionally, there is an object very close to G350.1-0.3, the round blue object on the right side of the image, called XMMU J172054.5-372652 that appears to be a neutron star, a common type of CCR. It may seem odd that the CCO is not actually at the center of G350.1-0.3, but there are two possible explanations for this. In other supernovas, the CCO has been “kicked out” of the central region by the explosion, so that after a few thousand years it is no longer anywhere near the center. XMMU J172054.5-372652 is rather far from G350.1-0.3 for this to be the case, but it isn't impossible. The other possible explanation is that XMMU J172054.5-372652 is actually at the center of the SNR, and the region is so dusty that another component of the SNR is actually still hidden from our view.

G350.1-0.3 is the most recent of several young SNRs discovered in recent years in our galaxy. So far, all the newly discovered young SNRs have been in dusty regions, and were only discovered after observations with x-ray and gamma ray telescopes.

This research was published as “The (Re-)Discovery of G350.1−0.3: A Young, Luminous Supernova Remnant and Its Neutron Star”, B. M. Gaensler, A. Tanna, P. O. Slane, C. L. Brogan, J. D. Gelfand, N. M. McClure-Griffiths, F. Camilo, C.-Y. Ng, and J. M. Miller; The Astrophysical Journal Letters, 680:L37–L40, 2008 June 10
Additional information and quotes for this article were taken from the ESA news article “Detective astronomers unearth hidden celestial gem” at http://www.esa.int/esaCP/SEM1OPUG3HF_index_0.html
The radio and x-ray composite image came from http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=42879

Related stories:: Neutron star observations provide groundbreaking test of relativity.

Imaging Stars with CHARA

The Center for High Angular Resolution Astronomy (CHARA) is a six telescope optical/infrared array on Mount Wilson in California. Astronomers the University of Michigan designed and built the infrared combiner used to image the surfaces of stars and close binaries. John Monnier gave an invited talk at the summer 2008 meeting of the American Astronomical Society (AAS) on “Imaging with the CHARA Interferometer.”

Professor Monnier began his talk with the Hubble Deep Field image, to illustrate how difficult it is to study stars. In this image, galaxies billions of light years distant are resolved well enough to distinguish their types and basic characteristics. However, the one star in the image, identifiable by the diffraction spikes, is a single point of light. That star is within our own galaxy, a few thousand light years distant at most. In order to resolve even the closest stars, we need 10 times better resolution than the resolution we need to identify most distant galaxies in the universe.

The CHARA interferometer has a resolution of 0.3 – 1 milli-arc-second. That’s roughly the same as being able to distinguish a human hair at a distance of 10 football fields, and is small enough to resolve large surface features on nearby large stars. The first star imaged by CHARA was Altair, and the results were published in Science in May 2007.

According to the Von Zeipel model, massive stars that rotate rapidly should exhibit gravity darkening. The equatorial region of a rapidly rotating star will bulge out, allowing it to cool, which causes it to become somewhat dimmer. This effect is known as gravity darkening. Since the equator is dimmer than the pole, the angle of the star with respect to us can affect how bright the star looks. For example if we are looking at the star’s pole, it will look brighter than it should, which will cause astronomers to underestimate its distance from us, and overestimate its mass.

CHARA images of Altair show it is longer on one axis than the other and exhibits equatorial darkening, clearly indicating it is a rapid rotator. However, the amount of darkening seen in the observations is greater than that predicted by the Von Zeipel model. This is probably because the model assumes the stars rotate like a solid body, like the Earth. The observations fit better with models that assume differential rotation, like the Sun, where the equator actually rotates faster than the poles.
CHARA has also imaged Vega, Achenar, Regulus, and Aldeberan, and shown all of them are rapid rotators that exhibit gravity darkening. Papers on these stars are forthcoming.

These models could eventually be used to measure the mass of individual stars. The temperature gradation shows the star’s inclination and shape. The shape can be used to determine the centrifugal force, which is determined by gravity. Since gravity depends only on the mass, knowing the force of gravity leads to the star’s mass. Observations to test this are being planned.

In addition to imaging individual stars, CHARA holds great promise for imaging tight binary systems. A team headed by graduate student Ming Zhao recently imaged beta-Lyrae, the tightest binary system ever resolved. Their image partially resolves the accretion disk between the two stars. CHARA can resolve features as small as 150 micro-arc-seconds for close binary stars.

More information and images will be coming out soon, in the paper “First Resolved Images of the Eclipsing and interacting binary \beta Lyrae” by M. Zhao, D. Gies, J. D. Monnier, N. Thureau, E. Pedretti, F. Baron, A. Merand, T. ten Brummelaar, H. McAlister, S. T. Ridgway, N. Turner, J. Sturmann, and L. Sturmann, which is currently undergoing review.

Related stories:: Astronomers Capture First Image of the Surface of a Sun-Like Star