View Full Version : Brown Dwarf Discovered in Planetary System

2006-Sep-19, 03:49 AM
NASA's Spitzer Space Telescope has directly imaged a small brown dwarf star orbiting a larger star - the first time this has ever been seen. The brown dwarf, HD 3651, is classified as a "T dwarf", has about 50 times the mass of Jupiter, and orbits about 10 times the distance from the Sun to Pluto. Astronomers theorized that the system contained a brown dwarf, because a Saturn-sized planet had a strangely elliptical orbit; something was tugging on it.

Read the full blog entry (http://www.universetoday.com/2006/09/18/brown-dwarf-discovered-in-planetary-system/)

2006-Sep-19, 12:42 PM
It is interesting to speculate as to how such an object formed so far from its primary star.

2006-Sep-19, 12:50 PM
whoops, i didn`t see this post....


John Mendenhall
2006-Sep-19, 04:30 PM
Thanks, Blob, good post.

I gather this is a G type (sun-like) star. Wouldn't that be interesting, if we had had a brown dwarf companion to Sol? Would we even be here?

2006-Sep-20, 02:04 PM
If having a brown dwarf in our system at 400 AU causes eliptical orbits of the planets, and if this causes us to not be here, then we don't see a brown dwarf at 400 AU in our system.

We also don't find ourselves in a metal poor globular cluster looking down on a grand barred spiral galaxy, but rather find ourselves in a metal rich outer band of a grand barred spiral looking out a metal poor globular clusters.

Of course, this brown dwarf isn't actually triangular. That's due to the less-than-perfect secondary that Spitzer has. Don't get me wrong, the Spitzer is wonderful. Amazing work is coming out of this less than 1-meter instrument. I can hardly wait for the James Web. Spitzer on steroids.

2006-Sep-21, 09:42 AM
Title: The Spectrum of HD 3651B: An Extrasolar Nemesis?
Authors: Adam J. Burgasser (MIT)

I present detailed analysis of the near-infrared spectrum of HD 3651B, a faint, co-moving wide companion to the nearby planet-hosting star HD 3651. The presence of strong H2O and CH4 absorption bands confirm this source as a late T-type brown dwarf with spectral type T8. Application of the technique of Burgasser, Burrows & Kirkpatrick yields Teff = 840 80 K, log(g) = 4.9 0.2, M = 30 10 MJup and an age in the range 0.7-3.4 Gyr, making HD 3651B a slightly warmer analogy to the field T8 2MASS 0415-0935. The derived age for this companion is somewhat better constrained than estimates for its primary, which ranges from ~2 Gyr to >12 Gyr. As a widely orbiting massive object to a known planetary system that could potentially harbour terrestrial planets in its habitable zone, HD 3651B may play the role of Nemesis in this system.

Read more (http://arxiv.org/PS_cache/astro-ph/pdf/0609/0609556.pdf) (19kb, PDF)

John Mendenhall
2006-Sep-26, 03:41 PM
Excellent, excellent, excellent letter by Burgasser available at Blob's previous post above. Well reasoned, factual, supported, peer reviewed and very thought provoking. This is something worth bringing up on the Long Now website, and that's where I'm headed now.

2006-Oct-20, 12:48 PM
It is interesting to speculate as to how such an object formed so far from its primary star.It may be better to think of them as a binary star system rather than as one being a primary. They could have formed from the same molecular cloud or iginally, or they may have captured each other later.

Universe today is carrying the story yesterday; it's how I found here again. I've been gone since May 15th. I noticed that they made a slight error though. They said the brown dwarf was 20 to 60 solar masses. Tough for that to be a brown dwarf. So I googled around to verify, finding here in the meantime, and found an abstract from Harvard that confirmed that it should have been 20 to 60 Jupiter masses.