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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-1997
DTSTART:20101028T203000Z
DURATION:PT1H0M0S
DTSTAMP:20260506T160929Z
LAST-MODIFIED:20101012T134001Z
LOCATION:4421 Sterling Hall
SUMMARY:Recent results from the Cosmic Origins Spectrograph HD 209458b
....\, Astronomy Colloquium\, Jeffrey Linsky\, JILA\, University of Co
lorado
DESCRIPTION:209458b was the first transiting planet to be studied in d
etail.
\nIt is a Jupiter mass exoplanet with a 3.5 day orbit
around a solarlike star. We have used the new Cosmic Origins Spectrogr
aph on Hubble to obtain very sensitive ultraviolet spectra during tran
sit and three nontransit phases in order to measure the mass loss prop
erties of the exoplanet. During transit\, absorption by singly-ionized
carbon and doubly-ionized silicon in the planet's exosphere reduces
the observed stellar emission by 8% compared to the 1.5% reduction pre
dicted by the planet's size. Velocity resolution of these line profile
s leads to estimates of the mass loss rate and the identification of e
nhanced massloss directed away from the star. The planet has a cometli
ke tail!
\n
\n I will also describe our preliminary analy
sis of molecular hydrogen pumping and fluorescence in the disks of pre
main sequence stars. The origin of the bright fluorescent emission se
en in the ultraviolet spectra of these stars has been ascribed to pump
ing by the stellar Lyman-alpha emission line\, but until now there ha
s been no direct evidence for this pumping. The very sensitive COS ins
trument now allows us to observe absorption against the Lyman-alpha em
ission line at the pumping transitions. Energy balance between absorpt
ion and emission allows us to estimate the accretion rates for DF Tau
and V4046 Sag.
\n
\n
URL:https://www.physics.wisc.edu/events/?id=1997
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