2020A&A...640L..12H


C.D.S. - SIMBAD4 rel 1.7 - 2020.12.01CET00:41:20

2020A&A...640L..12H - Astronomy and Astrophysics, volume 640, L12-12 (2020/8-1)

CS Cha B: A disc-obscured M-type star mimicking a polarised planetary companion.

HAFFERT S.Y., VAN HOLSTEIN R.G., GINSKI C., BRINCHMANN J., SNELLEN I.A.G., MILLI J., STOLKER T., KELLER C.U. and GIRARD J.

Abstract (from CDS):


Context. Direct imaging provides a steady flow of newly discovered giant planets and brown dwarf companions. These multi-object systems can provide information about the formation of low-mass companions in wide orbits and/or help us to speculate about possible migration scenarios. Accurate classification of companions is crucial for testing formation pathways.
Aims. In this work we further characterise the recently discovered candidate for a planetary-mass companion CS Cha b and determine if it is still accreting.
Methods. MUSE is a four-laser-adaptive-optics-assisted medium-resolution integral-field spectrograph in the optical part of the spectrum. We observed the CS Cha system to obtain the first spectrum of CS Cha b. The companion is characterised by modelling both the spectrum from 6300Å to 9300Å and the photometry using archival data from the visible to the near-infrared (NIR).
Results. We find evidence of accretion and outflow signatures in Hα and OI emission. The atmospheric models with the highest likelihood indicate an effective temperature of 3450±50K with a log g of 3.6±0.5dex. Based on evolutionary models, we find that the majority of the object is obscured. We determine the mass of the faint companion with several methods to be between 0.07M and 0.71M with an accretion rate of M=4x10–11±0.4M/yr.
Conclusions. Our results show that CS Cha B is most likely a mid-M-type star that is obscured by a highly inclined disc, which has led to its previous classification using broadband NIR photometry as a planetary-mass companion. This shows that it is important and necessary to observe over a broad spectral range to constrain the nature of faint companions.

Abstract Copyright: © ESO 2020

Journal keyword(s): planets and satellites: individual: CS Cha B - stars: low-mass - accretion - accretion disks - stars: winds - outflows - techniques: imaging spectroscopy

VizieR on-line data: <Available at CDS (J/A+A/640/L12): table1.dat>

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 V* FW Tau Or* 04 29 29.703744 +26 16 53.06412       15.85   M5.5 118 0
2 V* HK Tau Or* 04 31 50.5722969258 +24 24 17.775488652 16.81   15.10     M0.5 300 1
3 V* CS Cha Or* 11 02 24.8849252208 -77 33 35.683462615   12.88 11.69   10.123 K2Ve 197 0
4 NAME Cha I MoC 11 06 48 -77 18.0           ~ 992 1
5 TWA 30B LM* 11 32 18.2184758367 -30 18 31.652412622         16.68 M4 33 0
6 TWA 30 Y*O 11 32 18.3109439046 -30 19 51.860228754   15.82 14.20 14.44 11.30 M5V 55 0
7 CD-25 11111 ** 15 49 15.3888 -26 00 52.452           A5Ve+A2IVe 26 0

    Equat.    Gal    SGal    Ecl

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2020.12.01-00:41:20

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