Discovery of a 5-10 M_J companion to 2MASS J04414489+2301513

Discovery of a Planetary-mass Companion to a Brown Dwarf in Taurus
http://arxiv.org/abs/1004.0539

Abstract wrote:

We have performed a survey for substellar companions to young brown dwarfs in the Taurus star-forming region using the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. In these data, we have discovered a candidate companion at a projected separation of 0.105" from one of the brown dwarfs, corresponding to 15 AU at the distance of Taurus. To determine if this object is a companion, we have obtained images of the pair at a second epoch with the adaptive optics system at Gemini Observatory. The astrometry from the Hubble and Gemini data indicates that the two objects share similar proper motions and thus are likely companions. We estimate a mass of 5-10 Mjup for the secondary based on a comparison of its bolometric luminosity to the predictions of theoretical evolutionary models. This object demonstrates that planetary-mass companions to brown dwarfs can form on a timescale of <=1 Myr. Companion formation on such a rapid timescale is more likely to occur via gravitational instability in a disk or fragmentation of a cloud core than through core accretion. The Gemini images also reveal a possible substellar companion (rho=0.23") to a young low-mass star that is 12.4" from the brown dwarf targeted by Hubble. If these four objects comprise a quadruple system, then its hierarchical configuration would suggest that the fragmentation of molecular cloud cores can produce companions below 10 Mjup.

by reading the paper I did'nt found the value of the masses of the possible stellar companion and of the companion of this star, nor the mass of the brown dwarf...

Quote :

The brown dwarf for which we have detected a substellar companion is 2MASS J04414489+2301513 (henceforth 2M J044144). It is a member of the Taurus star-forming region and it has a spectral type of M8.5 (Luhman 2006), which corresponds to a mass of 20 MJup for an age of 1 Myr (Chabrier et al.2000; Luhman et al. 2003). 2M J044144 exhibits mid-IR excess emission and strong H emission, indicating the presence of a circumstellar disk and active accretion, respectively (Luhman 2006; Luhman et al. 2010). Kraus & Hillenbrand (2007) identified a possible wide stellar companion at a separation of 12.''4 (a= 1700 AU at 140 pc). This candidate companion, 2MASS J04414565+2301580 (henceforth 2M J044145), has been spectroscopically confirmed as a young low-mass star, and hence a likely member of Taurus (M3-M4.5, Luhman et al. 2009; Kraus & Hillenbrand 2009)

About the mass of stellar companion you can take a look at references.

Quote :

The brown dwarf for which we have detected a substellar companion is 2MASS J04414489+2301513 (henceforth 2M J044144). It is a member of the Taurus star-forming region and it has a spectral type of M8.5 (Luhman 2006), which corresponds to a mass of ~20 M_Jup for an age of 1 Myr

Quote :

Given the uncertainties in its age (few Myr) and luminosity (±0.12 dex), 2M J044144 B could have a mass between 5 and 10 M_Jup

That wasn't terribly difficult to find. The later is in the abstract.

Edit: Edasich beat me to it by a few minutes. lol.

The worst is I can't find value for putative luminosity of brown dwarf primary in any of the papers available. I find only Teff, no luminosity.

Yeah they're kind of vague on it. Look at the graph on the last page. It shows a Log L/L_sol on the Y-axis and age on the X-axis.
The table on page 5 gives H and K magnitudes for all four bodies.

Edit: SIMBAD also gives the star's J magnitude.

Edit 2: Now here on the Extrasolar Planets Encyclopaedia (with an incorrect age for the system).

One more in the group. I wonder why DH Tauri has never been included amongst imaged planets. It is always confirmed by authors being a 11 Mj object, not likely a low-mass brown dwarf. Who knows?

Same for EK 60 b yet unpublished.

Necropost! Here's an update to this system of low-mass stars/brown dwarfs:

Bowler & Hillenbrand "Near-Infrared Spectroscopy of 2M0441+2301 AabBab: A Quadruple System Spanning the Stellar to Planetary Mass Regimes"
http://arxiv.org/abs/1509.01658

Nomenclature-wise, the system 2M0441+2301 = 2M044145 (Aab) + 2M044144 (Bab).

Quote :

Confirming the low mass of 2M0441+2301 Bb demonstrates that fragmenting molecular clouds can create companions which overlap in mass with bona fide planets formed in disks, implying that some of the directly imaged planets orbiting stars and brown dwarfs may represent the tail end of turbulent fragmentation rather than the tip of the iceberg of planet formation.