Publikationsdatum:
2019-06-27
Beschreibung:
We present SCExAO/CHARIS high-contrast imaging/JHK integral eld spectroscopy of And b, a directly imaged low-mass companion orbiting a nearby B9V star. We detect And b at a high signal-to-noise ratio and extract high-precision spectrophotometry using a new forward-modeling algorithm for (A-)LOCI complementary to KLIP-FM developed by Pueyo et al. And bs spectrum best resembles that of a low-gravity L0L1 dwarf (L0L1). Its spectrum and luminosity are very well matched by 2MASS J0141-4633 and several other 12.515 M(sub J) free-oating members of the 40 Myr old TucHor Association, consistent with a system age derived from recent interferometric results for the primary, a companion mass at/near the deuterium-burning limit (13(sup +12, sub -2) M(sub J)), and a companion-to-primary mass ratio characteristic of other directly imaged planets (q 0.005(sup +0.005, sub -0.001)). We did not unambiguously identify additional, more closely orbiting companions brighter and more massive than And b down to 0".3 (15 au). SCExAO/CHARIS and complementary Keck/NIRC2 astrometric points reveal clockwise orbital motion. Modeling points toward a likely eccentric orbit: a subset of acceptable orbits include those that are aligned with the stars rotation axis. However, And bs semimajor axis is plausibly larger than 55 au and in a region where disk instability could form massive companions. Deeper high-contrast imaging of And and low-resolution spectroscopy from extreme adaptive optics systems such as SCExAO/CHARIS and higher-resolution spectroscopy from Keck/OSIRIS or, later, IRIS on the Thirty Meter Telescope could help to clarify And bs chemistry and whether its spectrum provides an insight into its formation environment.
Schlagwort(e):
Astrophysics
Materialart:
GSFC-E-DAA-TN64795
,
The Astrophysical Journal (ISSN 0004-6256) (e-ISSN 1538-3881); 156; 6; 291
Format:
text
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