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A blog about astronomy, astrophysics, outreach, and any other random things I feel like ranting about. Most posts that appear on Research Blogging will be from the Jodcast News scripts which describe papers on astronomy published within the month prior to the broadcast date of the show. Or science fiction shorts inspired by research papers.
Our current model of the early universe says that, as it expanded and cooled after the Big Bang, quarks began to coalesce to form protons and neutrons which, when the temperature dropped far enough, began to form simple nuclei. Eventually this material, mainly hydrogen with some helium and trace amounts of lithium, began to clump together, forming the stars and galaxies that we see today. Heavier elements such as carbon, nitrogen and oxygen, in fact pretty much everything that makes up this pla........ Read more »
I've never been afraid of the dark.; When it's all you've ever known, it seems a rather silly notion.; But now... well, this seems different somehow.; Now we're all frightened.It wasn't always like this.; We all grew up with the stories about the old times, when there were colonies every few parsecs, all set on planets (artificial or otherwise) around healthy stars, and supply stations strung along the major trade routes likes beads of water on an invisible web.; The galaxy thrived back then, or........ Read more »
Braun, R., Popping, A., Brooks, K., & Combes, F. (2011) Molecular gas in intermediate-redshift ultraluminous infrared galaxies. Monthly Notices of the Royal Astronomical Society, 416(4), 2600-2606. DOI: 10.1111/j.1365-2966.2011.19212.x
Stars are bright because they generate heat and light through nuclear fusion processes in their cores, planets are visible because they reflect some of that light.; The percentage of light that is reflected, a quantity known as a planet's , varies depending on the nature of the planet's surface and its atmosphere.; Jupiter, with its thick bands of highly reflective cloud, has an albedo of 52%, while the Earth's is somewhat lower, only reflecting around 37% of the sunlight which falls on the surf........ Read more »
is often thought of as something that is only created in particle accelerators (or that only exists in science fiction movies), but it is actually present in small quantities throughout the universe.; Now, a team of researchers the presence of naturally occurring antimatter right here in the neighbourhood of the Earth.; This population of antiparticles originates from cosmic ray interactions in the Earth's upper atmosphere where they are subsequently trapped in the planet's magnetosphere.Anti-........ Read more »
O. Adriani, G. C. Barbarino, G. A. Bazilevskaya, R. Bellotti, M. Boezio, E. A. Bogomolov, M. Bongi, V. Bonvicini, S. Borisov, S. Bottai.... (2011) The discovery of geomagnetically trapped cosmic ray antiprotons. ApJ, 737, L29, 2011. arXiv: 1107.4882v1
This blog post is a news story from the Jodcast, aired in the March 2011 edition.
Hansen CJ, Bourke M, Bridges NT, Byrne S, Colon C, Diniega S, Dundas C, Herkenhoff K, McEwen A, Mellon M, Portyankina G, & Thomas N (2011). Seasonal erosion and restoration of Mars' northern polar dunes. Science (New York, N.Y.), 331 (6017), 575-8 PMID: 21292976... Read more »
Hansen CJ, Bourke M, Bridges NT, Byrne S, Colon C, Diniega S, Dundas C, Herkenhoff K, McEwen A, Mellon M.... (2011) Seasonal erosion and restoration of Mars' northern polar dunes. Science (New York, N.Y.), 331(6017), 575-8. PMID: 21292976
This blog post is a news story from the Jodcast, aired in the March 2011 edition.
Reines, A., Sivakoff, G., Johnson, K., & Brogan, C. (2011). An actively accreting massive black hole in the dwarf starburst galaxy Henize 2-10 Nature, 470 (7332), 66-68 DOI: 10.1038/nature09724... Read more »
Reines, A., Sivakoff, G., Johnson, K., & Brogan, C. (2011) An actively accreting massive black hole in the dwarf starburst galaxy Henize 2-10. Nature, 470(7332), 66-68. DOI: 10.1038/nature09724
In the news this month we roundup of some highlights from the 217th meeting of the American Astronomical Society held in Seattle during January. The annual meetings of the American Astronomical Society are the largest gatherings of astronomers on the planet, and the presentations cover topics across the whole field of astronomy and astrophysics, including observational results, theoretical studies and simulations. Here are some of the highlights from this year's meeting.Starting big, astronomers........ Read more »
SDSS-III collaboration: Hiroaki Aihara, Carlos Allende Prieto, Deokkeun An, Scott F. Anderson, Éric Aubourg, Eduardo Balbinot, Timothy C. Beers, Andreas A. Berlind, Steven J. Bickerton, Dmitry Bizyaev.... (2011) The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III. Astrophysical Journal Supplements. arXiv: 1101.1559v1
Wyithe JS, Yan H, Windhorst RA, & Mao S. (2011) A distortion of very-high-redshift galaxy number counts by gravitational lensing. Nature, 469(7329), 181-4. PMID: 21228870
Left over from the explosions of massive stars, are incredibly dense and compact objects, but very little is known about their internal structure. , spinning neutron stars with powerful jets of radio emission which act something like cosmic lighthouses, are useful probes of extreme physics such as and forms of matter so dense that investigating them in laboratories on the Earth is extremely difficult.Various models of the internal structure of a neutron star have been proposed, including vari........ Read more »
Demorest, P., Pennucci, T., Ransom, S., Roberts, M., & Hessels, J. (2010) A two-solar-mass neutron star measured using Shapiro delay. Nature, 467(7319), 1081-1083. DOI: 10.1038/nature09466
The most distant object in the known universe is a highly luminous , a single explosion discovered near maximum light, at a of 8.2, a time when the universe was only 630 million years old, less than 5 percent of its current age. The most distant known galaxy lies at a redshift of 6.96, the light we see now left the galaxy just 750 million years after the . However, both these records have now been broken by a galaxy discovered by the Hubble Space Telescope which has a redshift of 8.56 and an es........ Read more »
Lehnert, M., Nesvadba, N., Cuby, J., Swinbank, A., Morris, S., Clément, B., Evans, C., Bremer, M., & Basa, S. (2010) Spectroscopic confirmation of a galaxy at redshift z . Nature, 467(7318), 940-942. DOI: 10.1038/nature09462
Small lumps of rock hit the Moon quite regularly, but in 2009 two artificial projectiles impacted on the lunar surface in an experiment designed to search for water in the permanent shadows of a crater near the lunar south pole. Hints of subsurface water on the Moon had already been found in 1999 when NASA's spacecraft detected signatures of concentrated hydrogen, the "H" in "H2O", near the lunar poles. The Lunar CRater Observation and Sensing Satellite, or , was a low-cost mission launched tog........ Read more »
Colaprete, A., Schultz, P., Heldmann, J., Wooden, D., Shirley, M., Ennico, K., Hermalyn, B., Marshall, W., Ricco, A., Elphic, R.... (2010) Detection of Water in the LCROSS Ejecta Plume. Science, 330(6003), 463-468. DOI: 10.1126/science.1186986
Gladstone, G., Hurley, D., Retherford, K., Feldman, P., Pryor, W., Chaufray, J., Versteeg, M., Greathouse, T., Steffl, A., Throop, H.... (2010) LRO-LAMP Observations of the LCROSS Impact Plume. Science, 330(6003), 472-476. DOI: 10.1126/science.1186474
Hayne, P., Greenhagen, B., Foote, M., Siegler, M., Vasavada, A., & Paige, D. (2010) Diviner Lunar Radiometer Observations of the LCROSS Impact. Science, 330(6003), 477-479. DOI: 10.1126/science.1197135
Paige, D., Siegler, M., Zhang, J., Hayne, P., Foote, E., Bennett, K., Vasavada, A., Greenhagen, B., Schofield, J., McCleese, D.... (2010) Diviner Lunar Radiometer Observations of Cold Traps in the Moon's South Polar Region. Science, 330(6003), 479-482. DOI: 10.1126/science.1187726
Mitrofanov, I., Sanin, A., Boynton, W., Chin, G., Garvin, J., Golovin, D., Evans, L., Harshman, K., Kozyrev, A., Litvak, M.... (2010) Hydrogen Mapping of the Lunar South Pole Using the LRO Neutron Detector Experiment LEND. Science, 330(6003), 483-486. DOI: 10.1126/science.1185696
After massive stars like explode, the object left behind is thought to be either a or a black hole, depending on the final mass of the progenitor star. are neutron stars that have strong magnetic fields and behave somewhat like cosmic lighthouses, projecting beams of radio emission into space as they spin. Studying the pulses of radiation as the beams sweep past the Earth can provide valuable information on the physics of these extreme objects, allowing astronomers to probe physics under cond........ Read more »
Lyne, A., Hobbs, G., Kramer, M., Stairs, I., & Stappers, B. (2010) Switched Magnetospheric Regulation of Pulsar Spin-Down. Science, 329(5990), 408-412. DOI: 10.1126/science.1186683
are the violent explosions of massive stars, so bright that the events can be seen in distant galaxies. But not all apparent explosions are genuine supernovae. Some fall into the category of , the sudden increase in brightness of a star without the terminal explosion. One such impostor event was the , a star which is amongst the most massive known in the Milky Way. Located 7,500 light years away in the constellation of Carina, the star is five million times more luminous than the Sun and an est........ Read more »
Most of the discovered so far are in the class known as "", large gas giants orbiting close to their parent stars, since many of the search techniques used are most sensitive to this type of planet. Usually these planets are located close enough to their parent star that they orbit in just a few days, but a team that is orbiting so close to its parent star that it is actually being disrupted.The planet, known as WASP-12b, is located in the constellation of Auriga and was discovered in the , or........ Read more »
Fossati, L., Haswell, C., Froning, C., Hebb, L., Holmes, S., Kolb, U., Helling, C., Carter, A., Wheatley, P., Cameron, A.... (2010) METALS IN THE EXOSPHERE OF THE HIGHLY IRRADIATED PLANET WASP-12b. The Astrophysical Journal, 714(2). DOI: 10.1088/2041-8205/714/2/L222
One of the most spectacular examples of a star formation region in the nearby universe is , also known as the , located in the Large Magellanic Cloud. This region is a giant stellar nursery, similar to the , but much larger, containing many clusters of recently formed young, hot stars. Some of the young stars in the nebula are many tens of times more massive than the Sun, making them some of the most massive stars known. New observations, on May 5th, show that one particular star is travelling ........ Read more »
Most supernovae are classified as one of two different types of explosion: single massive short-lived stars that explode when their cores run out of fuel at the end of their lives and undergo gravitational collapse, and old evolved white dwarfs in binary systems which accrete hydrogen from a companion star before exploding catastrophically.; are generally seen only in regions of ongoing star formation since, by stellar standards, their supergiant progenitors do not live for very long. In contra........ Read more »
Perets, H., Gal-Yam, A., Mazzali, P., Arnett, D., Kagan, D., Filippenko, A., Li, W., Arcavi, I., Cenko, S., Fox, D.... (2010) A faint type of supernova from a white dwarf with a helium-rich companion. Nature, 465(7296), 322-325. DOI: 10.1038/nature09056
Kawabata, K., Maeda, K., Nomoto, K., Taubenberger, S., Tanaka, M., Deng, J., Pian, E., Hattori, T., & Itagaki, K. (2010) A massive star origin for an unusual helium-rich supernova in an elliptical galaxy. Nature, 465(7296), 326-328. DOI: 10.1038/nature09055
Closer to home, the planet Venus shows large amounts of evidence of volcanic activity. Despite being shrouded under a thick layer of cloud, spacecraft have been able to map the surface of our nearest neighbour using radar, leading to the realisation that much of the planet's surface is comparatively young, suggesting that at some point in the recent past the planet underwent a complete resurfacing. However the question remains whether Venus is currently a geologically active planet.... Read more »
Smrekar, S., Stofan, E., Mueller, N., Treiman, A., Elkins-Tanton, L., Helbert, J., Piccioni, G., & Drossart, P. (2010) Recent Hotspot Volcanism on Venus from VIRTIS Emissivity Data. Science, 328(5978), 605-608. DOI: 10.1126/science.1186785
Most known extrasolar planets are massive gas giants orbiting close to their parent stars. If one of these planets happens to pass directly between us and its parent star during its orbit, then sensitive spectroscopy can be used to determine the chemical make-up of its atmosphere. Models of such atmospheres predict which gases should be present and in what relative abundances, based on physical conditions such as the temperature. Recent infra red observations carried out with the have provided ........ Read more »
Stevenson, K., Harrington, J., Nymeyer, S., Madhusudhan, N., Seager, S., Bowman, W., Hardy, R., Deming, D., Rauscher, E., & Lust, N. (2010) Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b. Nature, 464(7292), 1161-1164. DOI: 10.1038/nature09013
Many stars vary in brightness, sometimes due to changes within the star itself such as novae or Cepheid variables, others because of external factors. One is , an F-type supergiant in the constellation of Auriga, located at an estimated distance of 625 parsecs (2,100 light years). Since its variable nature was discovered in the 1820s, the star has been seen to fade in brightness every 27.1 years. During these eighteen-month-long eclipses, the brightness of the star fades to around 50 per cent o........ Read more »
Kloppenborg, B., Stencel, R., Monnier, J., Schaefer, G., Zhao, M., Baron, F., McAlister, H., ten Brummelaar, T., Che, X., Farrington, C.... (2010) Infrared images of the transiting disk in the ε Aurigae system. Nature, 464(7290), 870-872. DOI: 10.1038/nature08968
In just fifteen years, have been discovered around stars other than the Sun using a variety of techniques. Even without the ability to directly image these other worlds, some of their properties can be determined. Most extra solar planets found so far are massive orbiting close to their parent stars, since these are the types of planets that the detection methods are most sensitive to. As develop and improve, astronomers are finding out more and more about these other worlds, including the co........ Read more »
Swain, M., Deroo, P., Griffith, C., Tinetti, G., Thatte, A., Vasisht, G., Chen, P., Bouwman, J., Crossfield, I., Angerhausen, D.... (2010) A ground-based near-infrared emission spectrum of the exoplanet HD 189733b. Nature, 463(7281), 637-639. DOI: 10.1038/nature08775
A long-standing question in the study of is whether the process was more efficient in the early universe than it is today. Stars form through the collapse of clouds of cold gas. As the collapse progresses, the of the cloud gets denser and hotter until begins and a star is born. In the local universe, however, cold molecular gas is relatively rare so star formation occurs slowly; the Milky Way forms new stars at a rate of only a few per year. More distant galaxies formed stars at a much higher........ Read more »
Tacconi, L., Genzel, R., Neri, R., Cox, P., Cooper, M., Shapiro, K., Bolatto, A., Bouché, N., Bournaud, F., Burkert, A.... (2010) High molecular gas fractions in normal massive star-forming galaxies in the young Universe. Nature, 463(7282), 781-784. DOI: 10.1038/nature08773
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