J/A+A/639/A11 Exocomets. A Spectroscopic Survey (Rebollido+, 2020)
Exocomets: A spectroscopic survey
Rebollido I., Eiroa C., Montesinos B., Maldonado J., Villaver E., Absil O.,
Bayo A., Canovas H., Carmona A., Chen C., Ertel S., Henning T.,
Iglesias D.P., Launhardt R., Liseau R., Meeus G., Moor A., Mora A.,
Olofsson J., Rauw G., Riviere-Marichalar P.
<Astron. Astrophys. 639, A11 (2020)>
=2020A&A...639A..11R 2020A&A...639A..11R (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Comets ; Spectroscopy
Keywords: star: general - planetary systems - comets: general - ISM: clouds -
circumstellar matter
Abstract:
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 beta Pic in the early 1980s, Monly 20 stars
have been reported to host exocomet-like events. 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.
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 CaII K&H
and NaI 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.
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 CaII and/or NaI 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 CaII K line are similar to
those observed in beta^L 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 vsini is higher. We also find
a weak trend with the presence of near-infrared excess and with
anomalous (lambda Boo-like) abundances, but this would require
confirmation by expanding the sample.
Description:
Spectra obtained with Mercator (La Palma, Spain), NOT (La Palma,
Spain) and Tigre (La Luz, Mexico) echelle spectrographs.
Observation dates range from September 2015 to September 2017.
They were reduced using instrument pipelines. Barycentric correction
has been applied to all spectra.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 35 111 List of studied stars
tablec1.dat 90 716 Observation log
list.dat 113 1617 List of spectra
sp/* . 1617 Individual spectra
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name
13- 14 I2 h RAh Simbad right ascension (J2000)
16- 17 I2 min RAm Simbad right ascension (J2000)
19- 23 F5.2 s RAs Simbad right ascension (J2000)
25 A1 --- DE- Simbad declination sign (J2000)
26- 27 I2 deg DEd Simbad declination (J2000)
29- 30 I2 arcmin DEm Simbad declination (J2000)
32- 35 F4.1 arcsec DEs Simbad declination (J2000)
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Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Star name
15- 19 A5 -- Note Note
21- 34 A14 --- Date1 Observation date (UT) (YYYYMMDDTHHMM)
35- 40 A6 --- Inst1 Instrument
46- 59 A14 --- Date2 Observation date (UT) (YYYYMMDDTHHMM)
60- 65 A6 --- Inst2 Instrument
71- 84 A14 --- Date3 Observation date (UT) (YYYYMMDDTHHMM)
85- 90 A6 --- Inst3 Instrument
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name
11 A1 --- Band [BR-] Band for observations with
Tigre telescope
13- 24 F12.8 deg RAdeg Right ascension (J2000)
28- 39 F12.8 deg DEdeg Declination (J2000)
42- 60 A19 "datime" Obs.Date Date of observation, YYYY-MM-DDThh:mm:ss
62- 66 I5 Kibyte Size Size of each file
68-113 A46 --- FileName Name of the spectrum in subdirectory sp
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 18 F18.13 0.1nm lambda Wavelength
20- 43 E24.18 --- Flux ? Flux
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Acknowledgements:
Isabel Rebollido, isabel.rebollido(at)uam.es
(End) Patricia Vannier [CDS] 12-Jun-2020