Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: ROXs 42B - Young binary M dwarf with substellar companion(s?) 2nd April 2014, 10:49 am | |
| A First-Look Atmospheric Modeling Study of the Young Directly-Imaged Planet-Mass Companion, ROXs 42Bb http://arxiv.org/abs/1404.0131 - Quote :
- We present and analyze JKsL′ photometry and our previously published H-band photometry and K-band spectroscopy for ROXs 42Bb, an object Currie et al. (2014) first reported as a young directly imaged planet-mass companion. ROXs 42Bb exhibits IR colors redder than field L dwarfs but consistent with other planet-mass companions. From the H2O-2 spectral index, we estimate a spectral type of L0 ± 1; weak detections/non-detections of the CO bandheads, NaI, and CaI support evidence for a young, low surface gravity object primarily derived from the H2(K) index. ROXs 42Bb's photometry/K-band spectrum are inconsistent with limiting cases of dust-free atmospheres (COND) and marginally inconsistent with the AMES/DUSTY models and the BT-SETTL models. However, ROXS 42Bb data are simultaneously fit by atmosphere models incorporating several micron-sized dust grains entrained in thick clouds, although further modifications are needed to better reproduce the K-band spectral shape. ROXs 42Bb's best-estimated temperature is Teff ∼ 1950--2000 K, near the low end of the empirically-derived range in Currie et al. (2014). For an age of ∼ 1--3 Myr and considering the lifetime of the protostar phase, ROXs 42Bb's luminosity of log(L/L⊙) ∼ -3.07 ± 0.07 implies a mass of 9+3−3 MJ, making it one of the lightest planetary mass objects yet imaged.
As for the nature of the second planet candidate, they find that the colours of the object are consistent with it being an early-type (A- or F-type) star redenned by interstellar dust. They conclude the object is not a second planetary mass companion. _________________ Caps Lock: Cruise control for 'Cool'!
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