Exocomets: A spectroscopic survey

Abstract

While exoplanets are now routinely detected, the detection of small bodies in extrasolar systems remains challenging. Since the discovery of sporadic events interpreted as exocomets (Falling Evaporating Bodies) around $\beta$ Pic in the early 80s, only $\sim$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 have been collected in 14 observing campaigns expanding over 2 years from both hemispheres. We have analysed the Ca ii K&H and Na i D lines in order to search for non-photospheric absorptions originated in the circumstellar environment, and for variable events that could be caused by outgassing of exocomet-like bodies. We have detected non-photospheric absorptions towards 50% of the sample, attributing a circumstellar origin to half of the detections (i.e. 26% of the sample). Hot circumstellar gas is detected in the metallic lines inspected via narrow stable absorptions, and/or variable blue-/red-shifted absorption events. Such variable events were found in 18 stars in the Ca ii and/or Na i lines; 6 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 $\beta$ Pic. While we do not find a significant trend with the age or location of the stars, we do find that the probability of finding CS gas in stars with larger vsin i 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.

arXiv commentAccepted in A&A on March 23rd 2020

References in corpus (95)

• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• A Hipparcos census of the nearby OB associations
• A giant planet imaged in the disk of the young star Beta Pictoris
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• A Revised Age for Upper Scorpius and The Star-Formation History Among the F-Type Members of the Scorpius-Centaurus OB Association
• Cometary Origin of the Zodiacal Cloud and Carbonaceous Micrometeorites
• HERMES: a high-resolution fibre-fed spectrograph for the Mercator telescope
• A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood
• Molecfit: A general tool for telluric absorption correction II. Quantitative evaluation on ESO-VLT X-Shooter spectra
• The Star-formation History and Accretion-Disk Fraction Among the K-Type Members of the Scorpius-Centaurus OB Association
• Debris Disk Evolution Around A Stars
• A Catalog of Multiplicity among Bright Stellar Systems
• The Structure of the Local Interstellar Medium V: Electron Densities
• On the age of the $\beta$ Pictoris moving group
• Planet Hunters X. KIC 8462852 - Where's the Flux?
• Rotation periods of 12 000 main-sequence Kepler stars: Dependence on stellar spectral type and comparison with v sin i observations
• DUst Around NEarby Stars. The survey observational results
• New Debris Disks Around Young, Low Mass Stars Discovered With The Spitzer Space Telescope
• Comparative statistics and origin of triple and quadruple stars
• A 40 Myr Old Gaseous Circumstellar Disk at 49 Ceti: Massive CO-Rich Comet Clouds at Young A-Type Stars
• The Carbon-Rich Gas in the Beta Pictoris Circumstellar Disk
• Exocometary gas in the HD 181327 debris ring
• The Collisional Evolution of Debris Disks
• New 3-D gas density maps of NaI and CaII interstellar absorption within 300pc
• The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets
• Predictions for the secondary CO, C and O gas content of debris discs from the destruction of volatile-rich planetesimals
• ALMA observations of the molecular gas in the debris disk of the 30 Myr old star HD 21997
• Circumstellar material in the Vega inner system revealed by CHARA/FLUOR
• Extrasolar planets and brown dwarfs around A-F type stars VI. High precision RV survey of early type dwarfs with HARPS
• Do Two Temperature Debris Disks Have Multiple Belts?
• Analysis of the Herschel DEBRIS Sun-like star sample
• A near-infrared interferometric survey of debris disc stars. III. First statistics based on 42 stars observed with CHARA/FLUOR
• Debris Disks in the Scorpius-Centaurus OB Association Resolved by ALMA
• Exocometary gas structure, origin and physical properties around $\beta$ Pictoris through ALMA CO multi-transition observations
• Disk Radii and Grain Sizes in Herschel-Resolved Debris Disks
• Molecular gas in debris disks around young A-type stars
• Structure and evolution of debris disks around F-type stars: I. Observations, database and basic evolutionary aspects
• ALMA observations of the $\eta$ Corvi debris disc: inward scattering of CO-rich exocomets by a chain of 3-30 M${}_{\oplus }$ planets?
• Likely Transiting Exocomets Detected by Kepler
• The VLT/NaCo Large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits: I- Sample definition and characterization
• A near-infrared interferometric survey of debris-disc stars. IV. An unbiased sample of 92 southern stars observed in H-band with VLTI/PIONIER
• The Spatial Structure of the beta Pictoris Gas Disk
• The Nearby, Young, Argus Association: Membership, Age, and Dusty Debris Disks
• Metallicity of solar-type stars with debris discs and planets
• Braking the Gas in the beta Pictoris Disk
• A Trend Between Cold Debris Disk Temperature and Stellar Type: Implications for the Formation and Evolution of Wide-Orbit Planets
• Exocomets in the circumstellar gas disk of HD 172555
• A Comprehensive Census of Nearby Infrared Excess Stars
• Gas and dust in the Beta Pictoris Moving Group as seen by the Herschel Space Observatory
• Planetesimal driven migration as an explanation for observations of high levels of warm, exozodiacal dust
• Molecular gas in young debris disks
• Transiting exocomets detected in broadband light by TESS in the $\beta$ Pictoris system
• Stirring in massive, young debris discs from spatially resolved Herschel images
• Herschel Observations of Gas and Dust in the Unusual 49 Ceti Debris Disk
• First optical images of circumstellar dust surrounding the debris disk candidate HD 32297
• A near-infrared interferometric survey of debris-disc stars. V. PIONIER search for variability
• Modeling the HD32297 Debris Disk with Far-IR Herschel Data
• Gas Absorption Detected from the Edge-on Debris Disk Surrounding HD32297
• Gas and dust around A-type stars at tens of Myr:signatures of cometary breakup
• HD 172555: detection of 63 microns [OI] emission in a debris disc
• Inner mean-motion resonances with eccentric planets: A possible origin for exozodiacal dust clouds
• Spitzer Limits On Dust Emission and Optical Gas Absorption Variability Around Nearby Stars with Edge-On Circumstellar Disk Signatures
• Gaia's view of the $\lambda$ Boo star puzzle
• Volatile-Rich Circumstellar Gas in the Unusual 49 Ceti Debris Disk
• Gas and dust in the TW Hydrae Association as seen by the Herschel Space Observatory
• Exposing the Gas Braking Mechanism of the beta Pictoris Disk
• An evaluation of the membership probability of 212 $\lambda$ Boo stars: I. A Catalogue
• Discovery of an Edge-on Debris Disk with a Dust Ring and an Outer Disk Wing-tilt Asymmetry
• Subaru/SCExAO First-Light Direct Imaging of a Young Debris Disk around HD 36546
• Does warm debris dust stem from asteroid belts?
• The co-existence of hot and cold gas in debris discs
• Fundamental Properties of Co-Moving Stars observed by $Gaia$
• Spatially resolved imaging of the two-component eta Crv debris disk with Herschel
• Exocomet signatures around the A-shell star $\Phi$ Leo?
• Debris Disks Around Nearby Stars with Circumstellar Gas
• Chemical fingerprints of hot Jupiter planet formation
• Scattering of exocomets by a planet chain: exozodi levels and the delivery of cometary material to inner planets
• Searching for chemical signatures of brown dwarf formation
• Debris disks with multiple absorption features in metallic lines: circumstellar or interstellar origin?
• Origin and evolution of two-component debris discs and an application to the q${}^1$ Eridani system
• Spitzer IRS Spectroscopy of the 10 Myr-old EF Cha Debris Disk: Evidence for Phyllosilicate-Rich Dust in the Terrestrial Zone
• Extrasolar comets : the origin of dust in exozodiacal disks?
• Herschel Observations of Dusty Debris Disks
• Lambda Boo Abundance Patterns: Accretion from Orbiting Sources
• Hot exozodiacal dust: an exocometary origin?
• The Little Dippers: Transits of Star-grazing Exocomets?
• The Low Velocity Wind from the Circumstellar Matter Around the B9V Star sigma Herculis
• Dependence of Kinematics on the Age of Stars in the Solar Neighborhood
• The lambda Bootis stars
• The $\delta$ Scuti pulsations of $\beta$ Pictoris as observed by ASTEP from Antarctica
• IR-excesses around nearby Lambda Boo stars are caused by debris disks rather than ISM bow waves
• Spectral Evidence for an Inner Carbon-Rich Circumstellar Dust Belt in the Young HD36546 A-Star System
• Discovery of δ Scuti Pulsations in the Young Hybrid Debris Disk Star HD 156623
• HR 10: A main-sequence binary with circumstellar envelopes around both components. Discovery and analysis
• An unusually large gaseous transit in a debris disc

Cited by in corpus (29)

• The vertical structure of debris disks and the impact of gas
• Herbig Stars: A Quarter Century of Progress
• A new sample of warm extreme debris disks from the ALLWISE catalog
• Primordial or Secondary? Testing models of debris disk gas with ALMA
• Gas trapping of hot dust around main-sequence stars
• Vertical evolution of exocometary gas: I. How vertical diffusion shortens the CO lifetime
• Minimal conditions for survival of technological civilizations in the face of stellar evolution
• Hot exozodis: cometary supply without trapping is unlikely to be the mechanism
• A Bayesian Analysis of Technological Intelligence in Land and Oceans
• Curves of growth for transiting exocomets: Application to Fe II lines in the Beta Pictoris system
• Evidence for the disruption of a planetary system during the formation of the Helix Nebula
• Imaging of exocomets with infrared interferometry
• A Radiatively Driven Wind from the eta Tel Debris Disk
• CHEOPS's hunt for exocomets: photometric observations of 5 Vul
• Abundances of refractory ions in Beta Pictoris exocomets
• The A-shell star Phi Leo revisited: its photospheric and circumstellar spectra
• Review and prospects of hot exozodiacal dust research for future exo-Earth direct imaging missions
• First detection of a disk free of volatile elements around a young A-type star: A sign of collisions between rocky planets?
• Hunting for exocomet transits in the TESS database using the Random Forest method
• Search for exocomets transits in Kepler light curves: Ten new transits identified
• Discovery of carbon monoxide emission from five debris disks around young A-type stars
• Spectroscopic and Photometric Behaviour of LP Ori
• Diversity of Exoplanets
• Flickers, Bursts, and Dips: Detecting Rapid Variability with the g(2) Autocorrelation Function
• HD 44892: The youngest (or oldest?) gas-harbouring debris disc around an intermediate mass star
• Follow-up of three exocomet-host candidates
• The search for gas in debris discs: ALMA detection of CO gas in HD 36546
• Potential sublimating exocomets around the young star PDS 70
• Visual inspection of potential exocomet transits identified through machine learning and statistical methods