Edasich dK star
Number of posts : 2267 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Circumbinary substellar companions at DoAr 21 9th September 2019, 2:49 am | |
| This is really outstanding Sub-stellar companions of the young weak-line T Tauri Star DoAr21 - Quote :
- The compact, non-thermal emission in DoAr21 has been studied with the VLBA to investigate the possibility that the residuals of the astrometry fitting are due to the reflex motion induced by a possible companion. We find that the fitting of VLBA astrometric observations of DoAr21 improves significantly by adding the orbital motions of three companions. We obtain an improved distance to the source of 134.6±1.0 pc, and estimate that the central star, DoAr21, has a mass of about 2.04±0.70 M⊙. We suggest that DoAr21 represents a unique case where two sub-stellar companions, DoAr21b and DoAr21c (mb∼35.6±27.2 Mjup and mc∼44.0±13.6 Mjup, respectively), have been found associated to a relatively low mass, pre-main sequence star. In addition, we find that this WTTau star is an astrometric double system, having a low-mass star companion, DoAr21B (mB∼0.35±0.12 M⊙), in a relatively eccentric orbit. The orbit of this low-mass stellar companion is compact, while the Brown Dwarfs are located in external orbits. DoAr21c has the strongest astrometric signature in the periodogram, while DoAr21B has a weak but significant signature. On the other hand, the astrometric signature of DoAr21b does not appear in the periodogram, however, this Brown Dwarf was directly detected in some of the VLBA observations. The estimated orbital periods of DoAr21B, DoAr21b and DoAr21c are PB∼92.92±0.02, Pb∼450.9±3.8 and Pc∼1013.5±25.3 days, respectively. Since the estimated age of this young star is about 0.4−0.8 Myrs, the detected Brown Dwarf companion is among the youngest companions observed to date.
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: Circumbinary substellar companions at DoAr 21 9th September 2019, 5:58 pm | |
| Massive primary, massive "planets"? The direct detection of DoAr21b suggests that the curse of astrometric "planet" discovery does not apply to this one, at least... | |
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