Astrocrash.net

As I transition to my new job at the ITC, this webpage will be receiving an overhaul (it hasn't been updated in months!). Expect to see many changes over the next few weeks, and pardon the mess!

The Nature paper on PS1-10jh, believed to be a disruption of a star by a supermassive black hole, has been unveiled today, along with a press release featuring some snapshots and movies of a simulation I ran of such a disruption. This event is a real game-changer, not just because it appears to be a relatively uncommon star that was disrupted (perhaps 1 out of 100 stars, at best), but also because it is the first flare that has been observed both during the rise and the decay phase, which will actually allow for more sophisticated models of stellar disruption to distinguish between possible models.

I'd like to provide some additional details on the movies generated for the press release, for those who are curious. The disruption shown is that of a star whose mass is less centrally concentrated than that of the Sun; this is more consistent with the hypothesis that this object is partially supported by degeneracy pressure. Also, the disruption simulation was performed assuming a $10^3:1$ mass ratio, whereas the actual disruption was likely to be $>10^6:1$ . This was done to be able to follow the fallback of material, as the larger the mass ratio, the longer this takes as compared to the time of the disruption itself. The dynamics of the disruption, and all of the qualitative effects seen in the video, should be similar to what is seen in the video, but the relative scales of the features to one another (for instance, the width of the stream as compared to the distance of the stream to the black hole) will be different for more reasonable mass ratios.

The question of whether the star that was disrupted is indeed the core of a red giant (as proposed by the authors) remains, in my opinion, unanswered, as there are other He-rich stars that may be capable of producing a similar flare. This question can only be addressed by our improving our models of stellar disruption, which our group is very busily doing.

If you use Google Chrome, you may have found that several months ago when they added their built-in PDF viewer that PDFs would download without a format attached if you disabled this viewer. This was a real pain in the butt for me, as I use Skim (which is far superior to the in-browser PDF viewer) to read papers.

I had been pleading, unsuccessfully, for Google to fix this issue, as well as many other scientists who use ArXiv daily. The latest post in the thread by Zhiyu Zhang brought up the fact that if you use the German mirror de.arxiv.org, the PDF files are properly tagged again.

This led me to make a change to Vox Charta's ArXiv links, which now automatically point to de.arxiv.org if it detects the user is using Chrome. Also, I found that through ADS' preferences that you can change your ArXiv mirror preference to the German mirror, ensuring that all ArXiv links point to this mirror. These changes completely solve the problem for me.

Update: I later learned that the APS mirror also handles PDFs correctly. This is probably a better option for those residing in the United States.

I have posted some movies and snapshots related to our latest project focusing on the disruption of giant planets. The paper describing the simulations and their implications will be posted later today on the ArXiv.

All of the new videos were uploaded to YouTube, which is widely compatible across all platforms and should hopefully play on most semi-modern computers. If you are having issues with playing the YouTube videos, you can downgrade the video quality to 480p or lower to achieve a better frame-rate. The movies posted previously from my other projects still require Quicktime, but I plan to export most of those to YouTube in the coming few days.

Our paper on white dwarf collisions has been featured in an article in Scientific American!

If you are interested in seeing what the collisions look like, I have just posted some movies from the simulations we performed in FLASH to the WD collisions project page. Check them out!

I have just updated the page for my project describing accretion in double degenerate systems. In addition to hosting a high-resolution copy of the paper that will appear on astro-ph later today, I have also posted several movies that show the simulation results. Check it out here!

Welcome to my new webpage/blog! Things are fairly minimal for now, but all of my publications are accessible by clicking the links on the right.