Study of Planet forming Systems Orbiting Intermediate-mass Stars

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Study of Planet forming Systems Orbiting
Intermediate-mass Stars
Image credit Caltech

• Sweta ShahIthaca College
• Advisor Dr. Luke Keller
• In collaboration with the NASA Spitzer Space
  Telescope InfraRed Spectrograph Disks Team

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Theory of Planet formation Adapted from
Hogerheide 1998
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Why intermediate mass (Herbig Ae Be) stars ?

• Hot and massive 12,000 - 18,000 K
• 2-10 solar mass
• Excess thermal (IR) radiation
• e Emission line spectra

Circumstellar disks in Orion Nebula (Hubble Space
Telescope Image McCaughrean ODell 1995)
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Spectral characteristics of the Accretion Disk

• Thermal IR excess
• PAH
• Dust -silicates

UV
mm
Spectral Energy Distribution (Malfait et al. 1998)
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Correlation of SED and disk geometry (Malfait et
al. 1998)
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Physical structure of the disks SEDs (UV-mm)
LL
LL
LL
LL
(Malfait et al. 1998)
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Spectral features - PAH?

• Polycyclic Aromatic Hydrocarbon
• Excited by UV radiation

Sloan, Keller, Leibensperger et al. 2005
very stable
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What is the shape of the disk?
How do we test this hypothesis?
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Measuring the strength of bumps in Infrared
continuum
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25
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Ultimate Goal
?!
IPAH
Disk evolution in time
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Thanks!(Any ?)
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Spitzer InfraRed Telescope Facility

• Background-limited sensitivity 3 180 ?m
• 85 cm f/12 beryllium R-C telescope, T lt 5.5K
• Three scientific instruments provide
• Imaging/photometry, 3-180 ?m
• Spectroscopy, 5-40 ?m (R 90 600)
• Spectrophotometry, 50-100 ?m
• 5.5 yr lifetime
• Launched on 25 August 2003
• Birth stone forsterite

IRS