Comments on: AAS #7: To survey, with love

By: Doug

Doug — Thu, 10 Jan 2008 15:04:31 +0000

Philosophically, astronomical surveys are contradictory. They are considered by most astronomers to be unexciting, plodding stuff. They take too long. They aren’t usually “cutting edge.” In some cases they are looked down upon. Until they are done, that is. Then they most often prove to be indispensible reference resources, and/or they show an effect or make a discovery that would have been impossible to find otherwise. So in retrospect, they get respect. But not always before.

By: Sergeant Zim

Sergeant Zim — Thu, 10 Jan 2008 12:53:42 +0000

Thanks, Wayne and DG. That’s one of the beauties of this site, and Science in general: if you don’t know something, ASK! Chances are, there will be somebody who does know, or if not, you might inspire yourself or somebody else to find out.

“Believe the man (person) who says he is searching for the truth. Fear the man who claims to have found it” - unknown.

By: UKIDSS world release « The e-Astronomer

UKIDSS world release « The e-Astronomer — Thu, 10 Jan 2008 11:26:09 +0000

[…] of UKIDSS has now gone public, with a press release at the AAS. The blogosphere is picking it up, here, here and here. You have no idea how nice it feels after a couple of weeks of STFC-cuts politics.. […]

By: DGKnipfer

DGKnipfer — Wed, 09 Jan 2008 18:59:06 +0000

Look at that, my answer came even as I was typing. I love this place.

By: DGKnipfer

DGKnipfer — Wed, 09 Jan 2008 18:57:14 +0000

IIRC Brown Dwarf Stars fuse Deuterium into Helium. Deuterium is an uncommon but stable form of heavy Hydrogen that has a single neutron. Does anybody on the board know how much mass is required to fuse Deuterium and how much mass is required to fuse common Hydrogen?

By: Wayne

Wayne — Wed, 09 Jan 2008 18:36:55 +0000

Sergeant Zim,

Of course, everything depends on the definition you are using, but the most common breakover point I’ve heard between giant planet and brown dwarf is 13 Jupiter masses. Above this mass, there is a brief period of deuterium fusion that makes the object definitely “starlike”. You have to get up to about 60 Jupiter masses to get normal hydrogen burning, at which point it would be a red dwarf star. Others may like to disagree or refine this definition, but it’s a pretty good rule of thumb.

BA, do you have a mass for that coolest-yet brown dwarf?

By: Andy C

Andy C — Wed, 09 Jan 2008 18:28:18 +0000

“And the UKIRT survey isn’t even done! When it’s complete, in 2012, they will have detected 100 million galaxies”

That assumes that the recent funding cuts from STFC are reversed, as UKIRT is one of the facilities under threat. The petition to the PM is ongoing and has over 11,000 signatories now; let’s hope it works!