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  • September 28, 2010
  • 02:23 PM

What Happens When A White Dwarf Collides With A Neutron Star?

by Joseph Smidt in The Eternal Universe

                             Image via WikipediaPaschalidis et al. recently simulated what will happen when a white dwarf collides with a neutron star in a head on collision incorporating the effects of general relativity.

In each case I will list the mass of the white dwarf and neutron star in solar masses, (meaning the mass of these objects after dividing my the mass of the sun) the ratio of

... Read more »

Vasileios Paschalidis, Zachariah Etienne, Yuk Tung Liu, & Stuart L. Shapiro. (2010) Head-on collisions of binary white dwarf--neutron stars: Simulations in full general relativity. Submitted to PRD. arXiv: 1009.4932v1

  • July 30, 2010
  • 08:42 AM

Not the bang they were looking for

by Niall in we are all in the gutter

A satellite detects a bright burst of gamma-rays. Within minutes telescopes swing in to action expecting to see a massive star being torn apart by a cataclysmic explosion in a far-flung corner of the universe. But that wasn't what they found........... Read more »

Rachel A. Osten, Olivier Godet, Stephen Drake, Jack Tueller, Jay Cummings, Hans Krimm, John Pye, Valentin Pal'shin, Sergei Golenetskii, Fabio Reale.... (2010) The Mouse that Roared: A Superflare from the dMe Flare Star EV Lac detected by Swift and Konus-Wind. Accepted for publication in the Astrophysical Journal. arXiv: 1007.5300v1

  • July 16, 2010
  • 11:58 AM

Does one size fit all when it comes to star formation?

by Kelly Oakes in Basic Space

It is widely known (among astrophysicists at least!) that disks of accumulated matter are an essential component in the formation of low mass stars. These disks form when a rotating cloud of dust and gas collapses, and they direct material from the cloud onto a protostar at the centre. This protostar keeps accreting more and [...]... Read more »

Kraus, S., Hofmann, K., Menten, K., Schertl, D., Weigelt, G., Wyrowski, F., Meilland, A., Perraut, K., Petrov, R., Robbe-Dubois, S.... (2010) A hot compact dust disk around a massive young stellar object. Nature, 466(7304), 339-342. DOI: 10.1038/nature09174  

  • June 25, 2010
  • 08:42 PM

Night of the Living Dead Stars

by Professor Astronomy in Professor Astronomy

Image Credit: NASA / Spitzer / JPL-Caltech

White dwarfs, the slowly cooling remains of stars that have completed their life cycles, often seem to be the zombies of the night sky, devouring anything that happens to stray within their grasp.  In an article that will be appearing in an upcoming issue of the Astrophysical Journal, astronomers Patrick Dufour, Mukremin Kilic and collaborators discuss a recently-discovered white dwarf that seems to have devoured a dwarf planet.  Its name:&........ Read more »

P. Dufour, M. Kilic, G. Fontaine, P. Bergeron, F. -R. Lachapelle, S. J. Kleinman, & S. K. Leggett. (2010) The Discovery of the Most Metal-Rich White Dwarf: Composition of a Tidally Disrupted Extrasolar Dwarf Planet. The Astrophysical Journal. arXiv: 1006.3710v1

  • April 22, 2010
  • 02:36 PM

A Cataclysmic Variable in the Field of the Kepler Mission

by Professor Astronomy in Professor Astronomy

In September of 2008, I was sitting at the controls of the McDonald Observatory 2.1-meter Struve Telescope.  I was there to help some of my colleagues who work on a team associated with NASA's Kepler Mission.  This team, the Kepler Astroseismic Science Consortium, isn't on the lookout for planets.  They are studying the stars themselves, looking for variations in the light from stars caused by sound waves in the star.  The study of these sound waves, known as asteroseismol........ Read more »

Kurtis A. Williams, Domitilla de Martino, Roberto Silvotti, Ivan Bruni, Patrick Dufour, Thomas S. Riecken, Martin Kronberg, Anjum Mukadam, & G. Handler. (2010) Discovery of a Nova-Like Cataclysmic Variable in the Kepler Mission Field. The Astronomical Journal. arXiv: 1004.3743v1

  • April 8, 2010
  • 05:21 PM

Eps Aurigae’s dark secret (interferometry rules!)

by sarah in One Small Step

Since a few weeks some PhD students and postdocs have been organising astro-ph coffee meetings three times a week, where the youngsters in the department can sit together and chat about recent papers. The advantage of having these meetings for only students and postdocs is that we can admit to our utter ignorance about stuff [...]... 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  

  • March 15, 2010
  • 06:16 PM

a marauding star vs. our solar system

by Greg Fish in weird things

Imagine a speeding star plowing through the Oort Cloud surrounding our solar system and sending a stream of comets towards the Sun, a number of them smashing into Jupiter or diverted by the Jovian gravity into the inner solar system where the Earth could easily careen into them. The impacts could easily cause the kind [...]... Read more »

Bobylev, V. (2010) Searching for Stars Closely Encountering with the Solar System. Astronomy Letters, 2010 Vol. 36, No. 3. arXiv: 1003.2160v1

  • March 1, 2010
  • 10:53 AM

Stars Born as Planets

by Invader Xan in Supernova Condensate

Planets are resilient things. They can survive a lot of punishment from their host stars, with some planets having survived being broiled and others even having survived being engulfed as their parent star swells into a red giant. Amazingly, the means by which planets form is no less hardy, for instance being formed in the debris left after a supernova as pulsar planets. So if the method for planet formation is so rugged, what would happen if you started out with an extremely massive star? Could........ Read more »

  • January 25, 2010
  • 05:20 AM

…..And the rocks melt wi’ the sun

by Niall in we are all in the gutter

Happy Burns Day everybody. While I contemplate my failure to acquire a haggis and some Irn Bru in Honolulu, I thought I may as well find a tenuous link between Burns and astronomy.... Read more »

Schröder, K., & Connon Smith, R. (2008) Distant future of the Sun and Earth revisited. Monthly Notices of the Royal Astronomical Society, 386(1), 155-163. DOI: 10.1111/j.1365-2966.2008.13022.x  

  • January 3, 2010
  • 09:48 PM

In the News this month: first observational evidence of a new type of supernova

by Megan in Rigel

Stars the size and mass of our Sun end their lives by first expanding as , then shrinking to . Stars heavier than this however, come to a much more violent end.; For stars with masses between about 10 and 100 times that of the Sun, they continue in the core, until they run out of hydrogen. They then begin to fuse the helium nuclei together to form heavier elements such as carbon, nitrogen and oxygen. This carries on through the elements until iron, at which point the to form either a neutron s........ Read more »

Gal-Yam, A., Mazzali, P., Ofek, E., Nugent, P., Kulkarni, S., Kasliwal, M., Quimby, R., Filippenko, A., Cenko, S., Chornock, R.... (2009) Supernova 2007bi as a pair-instability explosion. Nature, 462(7273), 624-627. DOI: 10.1038/nature08579  

  • December 16, 2009
  • 08:56 PM

say, how far away is that black hole?

by Greg Fish in weird things

Trying to pin down the distance between our planet and a nearby black hole is a very tricky business. By virtue of being pinpoints of self-gravitating energy, black holes are usually about the size of a big city and very hard to observe directly. Their small size is also what makes it so difficult to [...]... Read more »

J. C. A. Miller-Jones, P. G. Jonker, V. Dhawan, W. Brisken, M. P. Rupen, G. Nelemans, & E. Gallo. (2009) The first accurate parallax distance to a black hole. ApJ Letters. arXiv: 0910.5253v1

  • November 23, 2009
  • 06:13 PM

Looking for planets? It’s all about the lithium!

by Invader Xan in Supernova Condensate

I have a lot of respect for planet hunters. It’s not an easy job. Discovering and confirming the existence of a planet requires a lot of patience, and I’d imagine it must be frustrating at times. So I’m sure a few planet hunters are rejoicing at the news that knowing which stars to look at just became a lot easier. All you have to do is look for lithium.... Read more »

Israelian, G., Mena, E., Santos, N., Sousa, S., Mayor, M., Udry, S., Cerdeña, C., Rebolo, R., & Randich, S. (2009) Enhanced lithium depletion in Sun-like stars with orbiting planets. Nature, 462(7270), 189-191. DOI: 10.1038/nature08483  

  • November 18, 2009
  • 01:58 AM

A New Kind of Supernova?

by Jon Voisey in Angry Astronomer

In general, supernova come in two flavors: The core collapse Type II supernovae, and the white dwarf over the Chandrasekhar limit, Type II supernova. The two are distinguished by the elemental composition of their spectra: Type II stars still have a hydrogen envelope and thus, hydrogen lines are prominent. Type I supernova, being the burned out cores of stars, don't have that envelope, so heavier elements, like silicon are present.However, the Supernova 2002bj defies classification. Initially, i........ Read more »

Poznanski, D., Chornock, R., Nugent, P., Bloom, J., Filippenko, A., Ganeshalingam, M., Leonard, D., Li, W., & Thomas, R. (2009) An Unusually Fast-Evolving Supernova. Science. DOI: 10.1126/science.1181709  

  • September 9, 2009
  • 12:30 PM

Here's to the weird ones.

by Jon Voisey in Angry Astronomer

Whether or not we know just how they work, type Ia Supernovae (SNe Ia) are held to be great standard candles for building our cosmic distance ladder. In so many cases where we can check their distance by other, more fundamental means there seems to be a very nice trend we can use.The theory behind these guys is described by the Chandrasekhar limit, that is, the maximum density at which you can compact an object before the gravity overwhelms internal support forces. For white dwarfs (the dead cor........ Read more »

  • August 2, 2009
  • 05:41 PM

Forming Stars: W51A - A Case Study

by Jon Voisey in Angry Astronomer

Ever since I was introduced to a Creationist claiming it's impossible to form new stars, I've been extra interested in journal articles that highlight how well our theory of stellar formation and evolution lines up with the evidence. It's been a pretty hot topic on this blog and a new ApJ article adds yet another confirmation that we're not just making things up when it comes to our knowledge of stars.The article looks at a star forming region called W51A that is a bubble in the gaseous cloud in........ Read more »

Kang, M., Bieging, J., Kulesa, C., & Lee, Y. (2009) TRIGGERED STAR FORMATION IN A DOUBLE SHELL NEAR W51A. The Astrophysical Journal, 701(1), 454-463. DOI: 10.1088/0004-637X/701/1/454  

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