Orbital motion of the young brown dwarf companion TWA 5 B

Details Orbital motion of the young brown dwarf companion TWA 5 B Orbital motion of the young brown dwarf companion TWA 5 B

2010-05-07

arxiv.org/abs/1005.1244v2

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

6 pages, 4 figures, accepted for publication in A&A; corrected typo in amplitude below Fig. 4

Scientific paper

With more adaptive optics images available, we aim at detecting orbital motion for the first time in the system TWA 5 A+B. We measured separation and position angle between TWA 5 A and B in each high-resolution image available and followed their change in time, because B should orbit around A. The astrometric measurement precision is about one milli arc sec. With ten year difference in epoch, we can clearly detect orbital motion of B around A, a decrease in separation by ~ 0.0054 arc sec per year and a decrease in position angle by ~ 0.26 degrees per year. TWA 5 B is a brown dwarf with ~ 25 Jupiter masses (Neuh\"auser et al. 2000), but having large error bars (4 to 145 Jupiter masses, Neuh\"auser et al. 2009). Given its large projected separation from the primary star, ~ 86 AU, and its young age ~ 10 Myrs), it has probably formed star-like, and would then be a brown dwarf companion. Given the relatively large changes in separation and position angle between TWA 5 A and B, we can conclude that they orbit around each other on an eccentric orbit. Some evidence is found for a curvature in the orbital motion of B around A - most consistent with an elliptic (e=0.45) orbit. Residuals around the best-fit ellipse are detected and show a small-amplitude (~ 18 mas) periodic sinusoid with ~ 5.7 yr period, i.e., fully consistent with the orbit of the inner close pair TWA 5 Aa+b. Measuring these residuals caused by the photocenter wobble - even in unresolved images - can yield the total mass of the inner pair, so can test theoretical pre-main sequence models.

Affiliated with

Also associated with

No associations

Rating

Orbital motion of the young brown dwarf companion TWA 5 B does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Orbital motion of the young brown dwarf companion TWA 5 B, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Orbital motion of the young brown dwarf companion TWA 5 B will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-223280