Recent from talks
Exocomet
Knowledge base stats:
Talk channels stats:
Members stats:
Exocomet
An exocomet, or extrasolar comet, is a comet outside the Solar System, which includes rogue comets and comets that orbit stars other than the Sun. The first exocomets were detected in 1987 around Beta Pictoris, a very young A-type main-sequence star. There are now (as of February 2019) a total of 27 stars around which exocomets have been observed or suspected.
The majority of discovered exocometary systems (Beta Pictoris, HR 10, 51 Ophiuchi, HR 2174, HD 85905, 49 Ceti, 5 Vulpeculae, 2 Andromedae, HD 21620, Rho Virginis, HD 145964, HD 172555, Lambda Geminorum, HD 58647, Phi Geminorum, Delta Corvi, HD 109573, Phi Leonis, 35 Aquilae, HD 24966, HD 38056, HD 79469 and HD 225200) are around very young A-type stars. The relatively old shell star Phi Leonis shows evidence of exocomets in the spectrum and comet-like activity was detected around the old F2V-type star Eta Corvi. In 2018 transiting exocomets were discovered around F-type stars, using data from the Kepler space telescope. Some late B-type star (e.g. 51 Ophiuchi, HD 58647) are known to host exocomets.
Observations of comets, and especially exocomets, improve our understanding of planet formation. Indeed, in the standard model of planet formation by accretion, planets are the result of the agglomeration of planetesimals, themselves formed by the coalescence of dust from the protoplanetary disk surrounding the star shortly after its formation. Thus, comets are the residuals of the volatile-rich planetesimals that remained in the planetary system without having been incorporated into the planets. They are considered fossil bodies that have seen the physical and chemical conditions prevailing at the time of planet formation.[citation needed]
Researching exocomets might provide answers to fundamental questions of the past of the solar system and the development of a life-supporting environment. Researchers can investigate the transport of water, cyanides, sulfides and pre-biotic molecules onto Earth-mass exoplanets with the help of exocomets.
The scientific term of an exocomet is Falling Evaporating Body (FEB). The term Evaporating Infalling Bodies (EIBs) was first used, but eventually the term FEBs was adopted from the "Falling Evaporating Bodies" model or Falling Evaporating Body (FEB) scenario.
A system of nomenclature for individual exocomets was proposed in 2026 by Alain Lecavelier des Etangs, Paul A. Strøm, and Darryl Z. Seligman. In this system, the designation of an exocomet begins with the name of its host star (as for exoplanets), followed by the letter C (for comet) and the date the exocomet was first observed, in the format YYYYMMDD. If multiple exocomets in the same system were observed on the same date, an additional lowercase letter is added. For example, the first observed exocomet (described by Ferlet et al. 1987) would be designated "β Pic C19841113".
This nomenclature is used in another 2026 paper with Lecavelier des Etangs as a co-author. This paper reports the detection of three exocomets around β Pictoris, all observed on the same day and designated β Pic C20250429a, b, and c.
The exocomets can be detected by spectroscopy as they transit their host stars. The transits of exocomets, like the transits of exoplanets, produce variations in the light received from the star. Changes are observed in the absorption lines of the stellar spectrum: the occultation of the star by the gas cloud coming from the exocomet produces additional absorption features beyond those normally seen in that star, like those observed in the ionized calcium lines. As the comet comes close enough to the star, cometary gas is evolved from the evaporation of volatile ices and dust with it. The absorption lines of a star hosting exocomets represent, beside a stable component, one or several variable redshifted components. The variable components change on short-time scales of one hour. The variable component represent the exocomets. The exocomet falls towards the star and any absorption line produced by the evaporation of the exocomet is redshifted compared to the absorption line of the star.
Hub AI
Exocomet AI simulator
(@Exocomet_simulator)
Exocomet
An exocomet, or extrasolar comet, is a comet outside the Solar System, which includes rogue comets and comets that orbit stars other than the Sun. The first exocomets were detected in 1987 around Beta Pictoris, a very young A-type main-sequence star. There are now (as of February 2019) a total of 27 stars around which exocomets have been observed or suspected.
The majority of discovered exocometary systems (Beta Pictoris, HR 10, 51 Ophiuchi, HR 2174, HD 85905, 49 Ceti, 5 Vulpeculae, 2 Andromedae, HD 21620, Rho Virginis, HD 145964, HD 172555, Lambda Geminorum, HD 58647, Phi Geminorum, Delta Corvi, HD 109573, Phi Leonis, 35 Aquilae, HD 24966, HD 38056, HD 79469 and HD 225200) are around very young A-type stars. The relatively old shell star Phi Leonis shows evidence of exocomets in the spectrum and comet-like activity was detected around the old F2V-type star Eta Corvi. In 2018 transiting exocomets were discovered around F-type stars, using data from the Kepler space telescope. Some late B-type star (e.g. 51 Ophiuchi, HD 58647) are known to host exocomets.
Observations of comets, and especially exocomets, improve our understanding of planet formation. Indeed, in the standard model of planet formation by accretion, planets are the result of the agglomeration of planetesimals, themselves formed by the coalescence of dust from the protoplanetary disk surrounding the star shortly after its formation. Thus, comets are the residuals of the volatile-rich planetesimals that remained in the planetary system without having been incorporated into the planets. They are considered fossil bodies that have seen the physical and chemical conditions prevailing at the time of planet formation.[citation needed]
Researching exocomets might provide answers to fundamental questions of the past of the solar system and the development of a life-supporting environment. Researchers can investigate the transport of water, cyanides, sulfides and pre-biotic molecules onto Earth-mass exoplanets with the help of exocomets.
The scientific term of an exocomet is Falling Evaporating Body (FEB). The term Evaporating Infalling Bodies (EIBs) was first used, but eventually the term FEBs was adopted from the "Falling Evaporating Bodies" model or Falling Evaporating Body (FEB) scenario.
A system of nomenclature for individual exocomets was proposed in 2026 by Alain Lecavelier des Etangs, Paul A. Strøm, and Darryl Z. Seligman. In this system, the designation of an exocomet begins with the name of its host star (as for exoplanets), followed by the letter C (for comet) and the date the exocomet was first observed, in the format YYYYMMDD. If multiple exocomets in the same system were observed on the same date, an additional lowercase letter is added. For example, the first observed exocomet (described by Ferlet et al. 1987) would be designated "β Pic C19841113".
This nomenclature is used in another 2026 paper with Lecavelier des Etangs as a co-author. This paper reports the detection of three exocomets around β Pictoris, all observed on the same day and designated β Pic C20250429a, b, and c.
The exocomets can be detected by spectroscopy as they transit their host stars. The transits of exocomets, like the transits of exoplanets, produce variations in the light received from the star. Changes are observed in the absorption lines of the stellar spectrum: the occultation of the star by the gas cloud coming from the exocomet produces additional absorption features beyond those normally seen in that star, like those observed in the ionized calcium lines. As the comet comes close enough to the star, cometary gas is evolved from the evaporation of volatile ices and dust with it. The absorption lines of a star hosting exocomets represent, beside a stable component, one or several variable redshifted components. The variable components change on short-time scales of one hour. The variable component represent the exocomets. The exocomet falls towards the star and any absorption line produced by the evaporation of the exocomet is redshifted compared to the absorption line of the star.
Recent media