Infrared H2 Emission Nebulousity Associated with KH 15D

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Infrared H2 Emission Nebulousity Associated with
KH 15D

• Tokunaga, A. T., Dahm, S., Gaessler, W., Hayano,
  Y., Hayashi, M., Iye, M., Kanzawa, T., Kobayashi,
  N., Kamata, Y., Minowa, Y., Nedachi, K., Oya, S.,
  Pyo, T., Saint-Jacques, D., Terada, H., Takami,
  H., Takato, N.,
• 2004, Astrophys. J., 601, L91.

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KH 15D is a peculiar variable star in NGC
2264 Discovered by Kearns Herbst, 1998, ApJ,
116, 261
More info http//www.astro.wesleyan.edu/research
/kh15d/
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Basic facts
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95-96
97-98
Light curve, Hamilton et al. 2005,
astro-ph/0507578 Note period of 48.37 days
99-00
01-02
03-04
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• Period 48.4 days, I14.5 to 18 mag
• No eclipses from 1913 to 1950
• Apparent phase shift

1967-1970
2001-2002
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Chiang Murray-Clay (2004, ApJ, 607, 913) and
Winn et al. (2004, ApJ, 603, L45) found that all
of the eclipse data can be explained as the
gradual occultation of a binary system. The edge
of the ring is very sharp-- in fact the light
curve suggests that it is like a knife edge. The
geometry of the system is shown in the next
slide. The sharp edge of the ring strongly
suggests that there is a planetary body confining
the edge of the ring. The inner edge of the ring
is about 1 AU and the outer edge is about 5 AU.
The binary itself has a semi-major axis of
about 0.2 AU.
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Edge of ring
From Chiang, E. Murray-Clay, R. 2004, ApJ,
607, 913
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Imaging by Subaru
Goal Looking for nebulousity. Used IRCS and AO
on Subaru.
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The imaging was first done in K-band to search
for nebulousity. The jet-like morphology was
unexpected. To make sure it is an emission
feature, narrow-band imaging in H2 was obtained.
Tokunaga et al. 2004, ApJ, 601, L91
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Narrow-band imaging with the H2 filter and the
K-continuum proves that the emission arises from
H2. Spectroscopy by Deming et al. (2004, ApJ,
601, L87) confirms this. The H2 emission is
enhanced at the position of KH 15D, implying a
physical association.
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White lines show outline of possible outflow
cavity.
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H2 image from the UH 2.2-m. This image shows
that the H2 emission is localized to KH 15D it
is not part of a larger structure.
KH 15D
Tokunaga et al. 2004, ApJ, 601, L91
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Major Questions

• What can we learn about the outflow process?
• Further observations of the light curve will
  constrain models in particular is there a planet
  that is defining the outer radius of the ring?
  Ring edge is very sharp.
• How stable is the ring?
• Could rings be as common as planets?
• What is this telling us about planet formation?