Coldest known failed stars found

[csmyth3025]

An article with the above title appeared in Space.com today. It can be found here:

http://www.space.com/scienceastronomy/u ... 00625.html

I'm guessing that the great number of these dim objects that this article implies has already been anticipated by astronomers and cosmologists. My guess is based on the analogy (a cliche, by now) that there are a lot more ants on Earth than there are elephants.

I'm also guesing that the theoretical total mass of theses dim objects has been taken into account when estimating the total mass and the distribution of mass in distant galaxies. Can you confirm this?

This question is, of course, related to the "dark matter" problem. Is it possible that there are enough of these dim objects to make any significant difference in the amount of baryonic matter that we estimate is contained in distant galaies?

Chris

 

[ramparts]

Gah. I like the SDC forums but SDC's reporting is awful. Could an article possibly be vaguer?

Anyway. Cosmologists wouldn't care about brown dwarfs - except, of course, as a matter of personal interest. But then biologists and novelists can be just as interested in them

These aren't going to solve the dark matter problem. There's simply not enough of them out there. We've known this for well over a decade by now; they simply don't provide nearly enough mass. These new T and Y dwarfs that they'll start finding with WISE are so ridiculously lightweight that even if there were more of them than in our wildest dreams, that would barely put a dent into the missing mass.

 

[csmyth3025]

Gah. I like the SDC forums but SDC's reporting is awful. Could an article possibly be vaguer?

Anyway. Cosmologists wouldn't care about brown dwarfs - except, of course, as a matter of personal interest. But then biologists and novelists can be just as interested in them

These aren't going to solve the dark matter problem. There's simply not enough of them out there. We've known this for well over a decade by now; they simply don't provide nearly enough mass. These new T and Y dwarfs that they'll start finding with WISE are so ridiculously lightweight that even if there were more of them than in our wildest dreams, that would barely put a dent into the missing mass.

Thanks Ramparts,

A careful reading of the article makes your point - as illustrated by the following sentence:

In fact, it is possible that WISE will even find more brown dwarfs within 25 light-years of the sun than the number of stars known to exist in this area of space.

Assuming that the author means that "this area of space" is within 25 light years, then that puts the number at >140 according to a response I found here:

http://answers.yahoo.com/question/index ... 033AAnMfBP

If each brown dwarf is ~.07 solar masses then that comes out to "more than" 10 additional solar masses. That could mean 11 solar masses or 111 solar masses.

Chris

 

[ramparts]

Yep - a few orders of magnitude less than we'd need to explain away the dark matter problem

 

[3488]

This is fascinating stuff.

WISE can produce a full sky map of these & HST / SPITZER / HERSCHEL can carry out more detailed obs. I wonder if even young rogue Jupiters, Saturns, Neptunes may be found 'nearby' i.e closer than the Alpha Centauri system. This will help in understanding rogue planets & failed stars (also rogue comets & asteroids, though they are far too small to detect with current means) of which IMO outnumber stars.

Fascinating.

Andrew Brown.

 

[csmyth3025]

This is fascinating stuff.

WISE can produce a full sky map of these & HST / SPITZER / HERSCHEL can carry out more detailed obs. I wonder if even young rogue Jupiters, Saturns, Neptunes may be found 'nearby' i.e closer than the Alpha Centauri system. This will help in understanding rogue planets & failed stars (also rogue comets & asteroids, though they are far too small to detect with current means) of which IMO outnumber stars.

Fascinating.

Andrew Brown.

There's speculation that our sun may have a Jupiter size planet or, perhaps, a brown dwarf companion star orbiting at a large distance due to the extremely elliptical orbit calculated for 90377 Sedna. This posibility is discussed in the Wikipedia article on Sedna which can be found here:

http://en.wikipedia.org/wiki/90377_Sedna

Chris