Coolest "star" yet found??

[heretic5]

http://dsc.discovery.com/news/2008/04/1 ... -star.html
offers a report about the lowest "stellar" temperature yet observed, about the same temperature as Mercury at its equator, 350 Celsius. So what does that make Venus which is 447 Celsius??

[junglelord]

Dare I say it....thats very cool.

[MGmirkin]

http://dsc.discovery.com/news/2008/04/1 ... -star.html
offers a report about the lowest "stellar" temperature yet observed, about the same temperature as Mercury at its equator, 350 Celsius. So what does that make Venus which is 447 Celsius??

Yep, interesting! Saw the article yesterday over here too:

(The Coldest Brown Dwarf Ever Observed: Closing The Gap Between Stars And Planets)
http://www.spacedaily.com/reports/The_C ... s_999.html
-or-
http://tinyurl.com/4t6d84

An international team of astronomers has discovered the coldest brown dwarf star ever observed. This finding, to be published in Astronomy and Astrophysics, is a new step toward filling the gap between stars and planets.

[...]

The brown dwarf is named CFBDS J005910.83-011401.3 (it will be called CFBDS0059 in the following). Its temperature is about 350degreesC and its mass about 15-30 times the mass of Jupiter, the largest planet of our solar system. Located about 40 light years from our solar system, it is an isolated object, meaning that it doesn't orbit another star.

[...]

The first brown dwarfs were detected in 1995. Since then, this type of stellar object has been found to share common properties with giant planets, even though differences remain. For example, clouds of dust and aerosols, as well as large amounts of methane, were detected in their atmosphere (for the coldest ones), just as in the atmosphere of Jupiter and Saturn.

However, there were still two major differences. In the brown dwarf atmospheres, water is always in gaseous state, while it condenses into water ice in giant planets; and ammonia has never been detected in the brown dwarf near-infrared spectra, while it is a major component of Jupiter's atmosphere.

CFBDS0059, the newly-discovered brown dwarf, looks much more like a giant planet than the known classes of brown dwarfs, both because of its low temperature and because of the presence of ammonia.

[...]

Cheers,
~Michael Gmirkin

[Ion01]

This reminds me of the article here http://www.msnbc.msn.com/id/18909876/ about a brown dwarf with polar jets. I don't know what the standard for qualifying an object as either a star or a planet but it is obviously something that needs to be reviewed.
I also remember reading somewhere that saturn emits more energy than it recieves from the sun (thermal energy maybe). I can't find it so maybe someone could help me out here but this type of stuff is great for the evidence that jupiter and saturn were once stars.
Also, how are they determining size? Other than redshift, which we know is flawed, the only other method I know of is to triangulate it by looking at it from both sides of our orbit around the sun but even that is incredibly inaccurate because these objects are at such distances that there is basically no triangle to use mathmatically because the angular difference is so small. Basically, it seems to me that these brown dwarfs may be the size of jupiter or smaller if we could be accurate in our measurements, we just don't know.

[starbiter]

If the "outgoing jets" are currents wouldn't they be going in both directions? Are the jets supposed to just stop somewhere?

[MGmirkin]

Well, and again, with jets, it seems like WAY too many objects have jets these days and they're only described with post hoc, ad hoc theories. Quite inconsistently at that! I mean, how can both black holes and brown dwarfs have polar jets? One is supposed to be a massive gravity well that nothing is supposed to be able to escape from. The other is a teeny tiny thing that basically was too insufficient (according to the standard model) to become a proper star. Yet both display the same feature across scales!

The black hole they explain "somehow" via an "accretion disk" mathemagically converting the inflowing matter / energy into energetic outflows along the poles. The brown dwarfs, on the other hand have no theoretical accretion disk dynamo to power them. So, how can these two extremely "different" objects produce the exact same feature?? They shouldn't. Certainly not through the same mechanism. And I don't really believe in coincidences... I mean, if we see "different" objects with bipolar ejecta, even across scales, shouldn't we be making the association and trying to find a common cause rather than hypothesizing 5 solutions to the same problem?

~Michael Gmirkin

[MGmirkin]

If the "outgoing jets" are currents wouldn't they be going in both directions? Are the jets supposed to just stop somewhere?

In many cases, yes. Plenty of images from space telescopes of bipolar ejecta!

~Michael Gmirkin