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Friday, December 16, 2011

Sagittarius A is about to get a Happy Meal






























Well, I was hoping to observe but the smog, stratus clouds and the mix is just stopping observing. I am hoping tomorrow to get out though I may have to head up to Rockport Reservoir to observe (past Park City and above the clouds and smog). So instead I have been reading some Astrobites entries that are highly interesting to me and I'll share information from both.

Earlier this year we saw a star get eaten by a black hole and sending off its fireworks. Well it looks like we'll see our own supermassive blackhole get active in the summer of 2013.

First, as this Astrobite entry on this by Susanna Kohler discusses, the first thing you have to do is go to this ESO animation of the stars that are in orbit around Sgr A* (the black hole at the center of our galaxy) and of an approaching gas cloud. That gas cloud is going to become a meal for the Sgr A* in 2013. This is based on observations which started in 2002 from the Very Large Telescope of the ESO which is in Chile. The gas cloud is roughly 3 Earth masses and is heading directly to Sgr A*.

In terms of where did this cloud of gas and dust came from the authors of the paper that the Astrobite reviews speculate that its origins came from near "Sgr A* from a massive O or Wolf-Rayet star." The cloud was sent out in a very extremely eccentric orbit around Sgr A* with a period of about 137 years ± 11 years. The gas/dust cloud will come closest to Sgr A* in the summer of 2013 which means those in the northern and southern hemispheres will have a great opportunity (with professional equipment) to view this. That is good news for anyone interested in this. What will happen? It looks like the gas/dust cloud will suffer tidal distortations as it falls into the accretion disk of the black hole and we may see x-rays emitted and material falling into the accretion disk. This could be huge because if the models hold up we just may see as Susanna Kohler states " it would provide one of the best probes yet of the physical conditions in the accretion zone around a black hole. Since we have an unusually good knowledge of the mass available for accretion, we’d be able to place stringent constraints on the physics of black-hole accretion after observing this event." Please click the link and go and see her article and the original article. Well worth the reading time.

The other Astrobite by Lucia Morgant and is titled Two Monster Black Holes in Nearby Galaxies is also a great read. Here is the link for that article and it discusses by reviewing a paper where the authors "were able to estimate a black hole mass of 9.7 billion solar masses in the elliptical galaxy NGC 3842, and a black hole of comparable or greater mass in the elliptical NGC 4889."
The review then discusses briefly how these super-massive black holes got this way, especially in an elliptical galaxy. Here is the link.

Here is the ESO release on the same subject.

To be fair, not everyone agrees with the paper or the information. Andrea Ghez of UCLA in this paper in Science offers an alternative view.

Hopefully tomorrow I'll be observing and then can report back on some items I have seen, observed and sketched.

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