Jupiter gets hit again!

Just last year an asteroid hit Jupiter. At that time no one saw the impact directly, but the aftermath was spotted by amateur astronomers.

Now Jupiter has been hit again, and some amateurs astronomers were lucky enough to capture the impact directly. Amazingly awesome.


For more info see this Bad Astronomy post.

Interesting Astrophysics: Jan 19 to Jan 30

Interesting astrophysics is back, now with two weeks worth of papers. There look interesting based on the titles and abstracts, but I haven't had time to actually read many of them seriously.

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Galaxies and Starbursts

X-ray emission from the extended disks of spiral galaxies
R.A. Owen, R.S. Warwick, arXiv:0901.4263 [ps, pdf, other]
Comments: Accepted for publication in Monthly Notices of the Royal Astronomical Society. 17 pages, 6 figures, 7 tables

I must admit to experiencing a moment of horror and panic when I saw the Owen paper on arXiv and read the abstract - had I been scooped on publishing my own hard-won observations again? Thankfully not, a different set of "normal" galaxies! A nice interesting paper.

GEMINI 3D spectroscopy of BAL + IR + Fe ii QSOs – I. Decoupling the BAL, QSO, starburst, NLR, supergiant bubbles and galactic wind in Mrk 231
S. Lipari, S. F. Sanchez, M. Bergmann, R. Terlevich, B. Garcia-Lorenzo, B. Punsly, E. Mediavilla, Y. Taniguchi, M. Ajiki, W. Zheng, J. Acosta and K. Jahnke, 2009, MNRAS, 392, 1295
Full Text: HTML, PDF (Size: 104115K)

Properties of the Molecular Gas in Starburst Galaxies and AGN
S. Mühle, E.R. Seaquist, C. Henkel, arXiv:0901.3468 [ps, pdf, other]
Comments: 6 pages, 4 figures, proceedings of the 9th European VLBI Network Symposium on "The role of VLBI in the Golden Age for Radio Astronomy and EVN Users Meeting", to appear in Proceedings of Science

Significant emphasis on everyones favorite starburst galaxy: M82.

Galactic Spiral Structure
Charles Francis, Erik Anderson, arXiv:0901.3503 [pdf]

Comments: A high resolution version of this file can be downloaded from this http URL

The Star Formation Histories of the M31 and M33 Spheroids
Thomas M. Brown, arXiv:0901.2577 [ps, pdf, other]
Comments: 7 pages, 2 figures, to appear in the proceedings of "Galaxy Evolution: Emerging Insights and Future Challenges," 11-14 November 2008, Austin, USA

A Wide-field High Resolution HI Mosaic of Messier 31: I. Opaque Atomic Gas and Star Formation Rate Density
Robert Braun, David Thilker, Rene Walterbos, Edvige Corbelli,arXiv:0901.4154 [ps, pdf, other]
Comments: Accepted for publication in ApJ, 34 pages, 20 figures

A Multi-Wavelength Infrared Study of NGC 891
C. Whaley, J. Irwin, S. Madden, F. Galliano, G. Bendo, arXiv:0901.4351 [ps, pdf, other]
Comments: 24 pages, 17 figures, 7 tables, accepted for publication in MNRAS

Distance to NGC 0247
Barry F. Madore, Wendy L. Freedman, J. Catanzarite, Mauricio Navarrete, arXiv:0901.3097 [ps, pdf, other]
Comments: Accepted ApJ Nov 2008: 51 pages, 19 figures, 16 tables

A Search for Radio Supernova Remnants in Four Irregular Galaxies
Laura Chomiuk, Eric Wilcots, arXiv:0901.2919 [ps, pdf, other]
Comments: Accepted by AJ. 17 pages, 9 figures. 23 additional figures will be available in the online version of the Astronomical Journal

The rotation curves shapes of late-type dwarf galaxies
R.A. Swaters, R. Sancisi, T.S. van Albada, J.M. van der Hulst, arXiv:0901.4222 [ps, pdf, other]
Comments: 22 pages, 2009 A&A 493, 871
Journal-ref: A&A, 493, (2009) 871

Diverging UV and Halpha fluxes of star forming galaxies predicted by the IGIMF theory
J. Pflamm-Altenburg, C. Weidner, P. Kroupa, arXiv:0901.4335 [ps, pdf, other]
Comments: accepted by MNRAS

Ram pressure stripping of the multiphase ISM in the Virgo cluster spiral galaxy NGC 4438
B. Vollmer, M. Soida, A. Chung, L. Chemin, J. Braine, A. Boselli, R.Beck, arXiv:0901.2770 [ps, pdf, other]
Comments: 8 pages, 6 figures, A&A, accepted for publication

Numerical Simulations of Hot Halo Gas in Galaxy Mergers

Manodeep Sinha, Kelly Holley-Bockelmann, arXiv:0901.3782 [ps, pdf, other]

Comments: Submitted to MNRAS. Paper with high-resolution images and associated movies available at this http URL

Correlations Between Supermassive Black Holes, Velocity Dispersions, and Mass Deficits in Elliptical Galaxies with Cores
John Kormendy, Ralf Bender, arXiv:0901.3778 [ps, pdf, other]
Comments: 4 pages, 4 figures, 1 table; requires emulateapj.sty
Journal-ref: 2009 ApJ 691 L142-L146

This Kormendy would be more interesting if it weren't so damned short. I suppose we'll have to wait for the real paper to come out to really assess this. This smacks of the "publish two for the price of one and get publication date priority" style of gaming the publish-or-perish system.

Different types of ultraluminous X-ray sources in NGC 4631
Authors: Roberto Soria, Kajal Ghosh, arXiv:0901.4302 [ps, pdf, other]
Comments: 12 pages, accepted by ApJ

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Numerical Astrophysics and Hydrodynamics

iVINE – Ionization in the parallel tree/sph code VINE: first results on the observed age-spread around O-stars
M. Gritschneder, T. Naab, A. Burkert, S. Walch, F. Heitsch and M. Wetzstein, 2009, MNRAS, 393, 21
Full Text: HTML, PDF (Size: 2038K)

Spectral Analysis in the Virtual Observatory
Thomas Rauch, Iliya Nickelt, arXiv:0901.4202 [ps, pdf, other]
Comments: 3 pages

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Cosmology

Missing Halo Baryons and Galactic Outflows
Romeel Davé, arXiv:0901.3149 [ps, pdf, other]
Comments: 7 pages, to appear in proc. "Galaxy Evolution: Emerging Insights and Future Challenges", ASP (uses asp2006.sty)

The Effects of Gas on Morphological Transformation in Mergers: Implications for Bulge and Disk Demographics
Philip F. Hopkins, Rachel S. Somerville, Thomas J. Cox, Lars Hernquist, Shardha Jogee, Dusan Keres, Chung-Pei Ma, Brant Robertson, Kyle Stewart, arXiv:0901.4111 [ps, pdf, other]
Comments: 19 pages, 13 figures, submitted to MNRAS

Apparent discordant redshift QSO-galaxy associations
Martin Lopez-Corredoira, arXiv:0901.4534 [ps, pdf, other]
Comments: invited talk, to be published in the proceedings of the conference "Evolution of Cosmic Objects through their Physical Activity (V. Ambartsumian 100th anniversary)", held at Byurakan Observatory (Armenia), on September 15th-18th, 2008. Eds. H. A. Harutyunian, H. Y. Terzian. Armenian Academy of Sciences

All I can say is that in the one case where I have really examined this sort of thing seriously (NGC 3628, which is mentioned in this article although not elaborated upon), both the qualitative claims of physical association between QSO and the NGC 3628 superwind, and the quantitative claims of the QSO's presence in the field of view being statistically unlikely simply failed to hold up under examination. See Strickland et al, 2004a, ApJS, 151, 193 (footnote 11).

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Astrophysical Plasmas

Giant cavities, cooling and metallicity substructure in Abell 2204
J. S. Sanders, A. C. Fabian and G. B. Taylor, 2009, MNRAS, 393, 71
Full Text: HTML, PDF (Size: 17147K)

The effect of photoionization on the cooling rates of enriched, astrophysical plasmas
Robert P. C. Wiersma, Joop Schaye and Britton D. Smith, 2009, MNRAS, 393, 99
Full Text: HTML, PDF (Size: 389K)

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Stars, Supernovae, Star Clusters, Planets etc.

Chemical Yields from Supernovae and Hypernovae
Ken'ichi Nomoto, Shinya Wanajo, Yasuomi Kamiya, Nozomu Tominaga, Hideyuki Umeda, arXiv:0901.4536 [ps, pdf, other]
Comments: 13 pages, 10 figures. To appear in the Proceedings of IAU Symposium 254 "The Galaxy Disk in Cosmological Context" (2008), eds. J. Andersen, J. Bland-Hawthorn, and B. Nordstrom (Cambridge University Press)

Title: Tangential Motions and Spectroscopy within NGC 6720, the Ring Nebula
C. R. O'Dell, W. J. Henney, F. Sabbadin, arXiv:0901.3185 [pdf, other]
Comments: Astronomical Journal, in press

Whilst this Planet Has Gone Cycling On: What Role for Periodic Astronomical Phenomena in Large Scale Patterns in the History of Life?
B.S. Lieberman, A.L. Melott, arXiv:0901.3173 [pdf]
Comments: 39 pages, 5 figures, to be published in the Biosphere volume of the International Year of Planet Earth Series, J. Talent, Ed

100 years since the Tunguska Explosion

The Tunguska Explosion took place on June 30th 1908, exactly 100 years ago today. Although it is almost certain that it was the result of an small asteroid or comet exploding in the atmosphere with an estimated yield(*) equivalent to 20 million tons of TNT (i.e. over a thousand times more energy than released by the atomic bomb dropped on Hiroshima), many mysteries still remain.

Scientific American had an interesting article on Tunguska in its June 2008 edition, on the search for a crater. Space.com has another article worth a look, which has some fun at the end by mentioning some of the more outlandish hypotheses put forward over the years: an alien space ship blowing up, a mini-black hole passing through the Earth, or Tesla's experimental death ray.

(*) The explosion of 1 ton of TNT is equivalent to the release of 4.18e9 Joules of energy (see here), so roughly the Tunguska explosion was about 8.4e15 Joules, or 8.4e22 ergs. By way of comparison the luminosity of the Sun is 3.845e33 ergs per second.

[The image is of trees flattened by the explosion, taken twenty years afterwards by the Kulik expedition. Source: APOD for 2007 November 14]

More evidence for ancient impactor as sources of Mars's North/South dichotomy

A variety of media outlets are reporting on a series of new papers that strengthen the case that the peculiar differences between the northern and southern hemispheres of Mars (e.g. see this topographic map of Mars, or this web page) are due to a very large impact by a proto-planetary object of order 1000 miles in diameter.

Kenneth Chang discusses this in an article in the NYT, although he awkwardly calls the impactor a "meteor." Clara Moskowitz at Space.com also discusses the story, as does JR Minkle at SciAm news (see if you can spot the mistake in the image caption accompanying the SciAm article).

[Image shown is a color-coded map of the elevation of Mars, from the Mars Orbiter Laser Altimeter, showing the low, smooth, northern hemisphere and the higher, cratered, south. Note that even recently (1999) this data was used to argue against an external cause for the north/south dichotomy.]