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JoeS
2009-May-19, 03:59 PM
I'm wondering how Hubble's upgrade (completed today) will benefit astronomers. For example, what phenomena will they be able to study now, that they weren't able to study before?

Joe

PraedSt
2009-May-19, 05:42 PM
Welcome to BAUT JoeS. :)

You might have stumbled upon this thread already, but in case you haven't, this link that will take you to....lots of other links, courtesy 01101001.

STS-125 Hubble Servicing Mission (http://www.bautforum.com/space-exploration/75496-sts-125-shuttle-mission-hubble-servicing-mission-4-a-17.html#post1491024)

Hope that helps.

JoeS
2009-May-19, 08:48 PM
Thanks PraedSt, I followed those links and it looks like more data on dark energy will be forthcoming, which sounds pretty cool.

"The installation of WFC3 and Cosmic Origins Spectrograph instruments on Hubble is one of the SM4 mission priorities. The WFC3 will study dark energy, the populations of stars in other galaxies beyond the Milky Way and remote galaxies previously beyond Hubble's vision. The capabilities of the ACS instrument are complementary and, to some extent, unique from WFC3. Having both instruments function together would give Hubble an extremely powerful imaging capability."

Joe

ngc3314
2009-May-19, 09:24 PM
Another major advance should come from the sensitivity of the Cosmic Origins Spectrograph (COS), whose design sacrifices things like long-slit capability and spatial resolution to maximize the detection of faint light. This should allow much better measurements of the hot gas between galaxies (the IGM, intergalactic medium) using quasars as background sources. Since the (fairly spotty) measurements of the characteristic highly-ionized species in this material from UV absorption lines indicate that there are more atoms there than in galaxies (and maybe even more "metal" atoms), improving these data will be a big deal for our knowledge of cosmology and galaxy evolution. The instrument will also do similarly improved things for study of stars and the physics of quasars.

(Paging Amber Robot!)

JoeS
2009-May-19, 10:17 PM
More matter between the galaxies than in the galaxies? What keeps it from clumping up into stars?

ngc3314
2009-May-19, 10:51 PM
More matter between the galaxies than in the galaxies? What keeps it from clumping up into stars?

It already did where the density was high enough (of dark matter initially, assisted by ordinary stuff when it collected densely enough). In the intergalactic medium, the density is ridiculously low (10-100 ions/cubic meter), and we can currently detect it only in the denser part of this range. Gravity continues to operate, but at these high temperatures and low densities, cosmic expansion may outrun cooling to change its phase. The density is very low, but the volume of the intergalactic gas is a lot larger than the volume inside galaxies, so current estimates are that it wins in the mass budget.

JoeS
2009-May-20, 02:48 AM
Thanks for the explanation. 10 to 100 ions per cubic meter sounds pretty sparse alright, but I guess I had always imagined it to be even more empty.

Joe

Amber Robot
2009-May-20, 07:46 PM
Another major advance should come from the sensitivity of the Cosmic Origins Spectrograph (COS), whose design sacrifices things like long-slit capability and spatial resolution to maximize the detection of faint light. This should allow much better measurements of the hot gas between galaxies (the IGM, intergalactic medium) using quasars as background sources. Since the (fairly spotty) measurements of the characteristic highly-ionized species in this material from UV absorption lines indicate that there are more atoms there than in galaxies (and maybe even more "metal" atoms), improving these data will be a big deal for our knowledge of cosmology and galaxy evolution. The instrument will also do similarly improved things for study of stars and the physics of quasars.

(Paging Amber Robot!)

You summed it up well. The design of COS is such that for its far-ultraviolet channel there is only one bounce -- the diffraction gratings have built-in aberration correction -- before the detector. This results in a great improvement in sensitivity over STIS in a comparable mode.