Transcript Infrared Spectroscopy and Imaging of KH 15D

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.
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/
Basic facts:
Position
RA, Dec: 06:41, +09:28
V, J, H, K
16.1, 13.7, 13.0, 12.8 mag
Spectral Type
K6-K7
Distance
760 pc
Luminosity
0.5 L_sun
Age
2-4 Myr
95-96
97-98
Light curve,
Hamilton et al.
2005, astroph/0507578
99-00
Note period of
48.37 days
01-02
03-04
•
•
•
Period 48.4 days, I~14.5 to ~18 mag
No eclipses from 1913 to 1950
Apparent phase shift:
1967-1970
2001-2002
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.
Edge of ring
From: Chiang, E. & MurrayClay, R. 2004, ApJ, 607, 913
Imaging by Subaru
Goal: Looking for nebulousity.
Used IRCS and AO on Subaru.
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
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.
White lines show outline of possible outflow cavity.
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
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?