Exocomets: A spectroscopic survey
Artikel i vetenskaplig tidskrift, 2020

Context. While exoplanets are now routinely detected, the detection of small bodies in extrasolar systems remains challenging. Since the discovery of sporadic events, which are interpreted to be exocomets (falling evaporating bodies) around β Pic in the early 1980s, only ∼20 stars have been reported to host exocomet-like events. Aims. We aim to expand the sample of known exocomet-host stars, as well as to monitor the hot-gas environment around stars with previously known exocometary activity. Methods. We have obtained high-resolution optical spectra of a heterogeneous sample of 117 main-sequence stars in the spectral type range from B8 to G8. The data were collected in 14 observing campaigns over the course of two years from both hemispheres. We analysed the Ca » II K&H and Na » I D lines in order to search for non-photospheric absorptions that originated in the circumstellar environment and for variable events that could be caused by the outgassing of exocomet-like bodies. Results. We detected non-photospheric absorptions towards 50% of the sample, thus attributing a circumstellar origin to half of the detections (i.e. 26% of the sample). Hot circumstellar gas was detected in the metallic lines inspected via narrow stable absorptions and/or variable blue- and red-shifted absorption events. Such variable events were found in 18 stars in the Ca » II and/or Na » I lines; six of them are reported in the context of this work for the first time. In some cases, the variations we report in the Ca » II K line are similar to those observed in β Pic. While we do not find a significant trend in the age or location of the stars, we do find that the probability of finding CS gas in stars with larger v sin i is higher. We also find a weak trend with the presence of near-infrared excess and with anomalous (λ Boo-like) abundances, but this would require confirmation by expanding the sample.

ISM: clouds

Kuiper belt: general

Stars: general

Comets: general


I. Rebollido

Universidad Autonoma de Madrid (UAM)

C. Eiroa

Universidad Autonoma de Madrid (UAM)

Calar Alto Astronomical Observatory

B. Montesinos

European Space Astronomy Centre (ESAC)

J. Maldonado

Istituto nazionale di astrofisica (INAF)

E. Villaver

Universidad Autonoma de Madrid (UAM)

O. Absil

Universite de Liège

A. Bayo

Universidad de Valparaíso

H. Canovas

European Space Astronomy Centre (ESAC)

A. Carmona

Universite Paul Sabatier Toulouse III

C. H. Chen

Space Telescope Science Institute (STScI)

S. Ertel

University of Arizona

T. Henning


D. P. Iglesias

Universidad de Valparaíso

R. Launhardt


René Liseau

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

G. Meeus

Universidad Autonoma de Madrid (UAM)

A. Moór

Magyar Tudomanyos Akademia

Eötvös Loránd University (ELTE)

A. Mora

European Space Astronomy Centre (ESAC)

J. Olofsson

Universidad de Valparaíso

G. Rauw

Universite de Liège

P. Riviere-Marichalar

Observatorio Astronómico Nacional (OAN)

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 639 A11


Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik




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