Exocomets: Now you see them, now you don't - Barry Welsh(SETI Talks 2017)
Δημοσιεύτηκε στις 27 Ιαν 2017
Present
technology does not enable us to view images of these kilometer-sized
infalling bodies, but the evaporation of gaseous products liberated from
exocomets that occurs close to a star can potentially cause small
disruptions in the ambient circumstellar disk plasma. For circumstellar
disks that are viewed “edge-on” this evaporating material may be
directly observed through transient (night-to-night and hour-to-hour)
gas absorption features seen at rapidly changing velocities. Using high
resolution spectrographs mounted to large aperture ground-based
telescopes, we have discovered 15 young stars that harbor swarms of
exocomets. In this lecture we briefly describe the physical attributes
of comets in our own solar system and the instrumental observing
techniques to detect the presence of evaporating exocomets present
around stars with ages in the 10 – 100 Myr range. We note that this work
has particular relevance to the dramatic fluctuations in the flux
recorded towards “Tabby’s star” by the NASA Kepler Mission, that may be
explained through the piling up of swarms of exocomets in front of the
central star.
technology does not enable us to view images of these kilometer-sized
infalling bodies, but the evaporation of gaseous products liberated from
exocomets that occurs close to a star can potentially cause small
disruptions in the ambient circumstellar disk plasma. For circumstellar
disks that are viewed “edge-on” this evaporating material may be
directly observed through transient (night-to-night and hour-to-hour)
gas absorption features seen at rapidly changing velocities. Using high
resolution spectrographs mounted to large aperture ground-based
telescopes, we have discovered 15 young stars that harbor swarms of
exocomets. In this lecture we briefly describe the physical attributes
of comets in our own solar system and the instrumental observing
techniques to detect the presence of evaporating exocomets present
around stars with ages in the 10 – 100 Myr range. We note that this work
has particular relevance to the dramatic fluctuations in the flux
recorded towards “Tabby’s star” by the NASA Kepler Mission, that may be
explained through the piling up of swarms of exocomets in front of the
central star.
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