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Detecting Brown Dwarfs in
Interacting Cataclysmic Binaries
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Recent observations and research indicate that interacting binaries may
harbor brown dwarfs (BD) as the mass donor if their orbital periods are
less than about 90 minutes. One such system, EF Eri, has been proven to
contain a BD mass donor (Harrison, Howell, et al, 2004 ApJ, 614, 947).
After a correlation of the 2MASS database with known ultra-short period
binaries, three systems have been identified that have orbital periods
less than about 90 minutes and contain highly magnetic white dwarfs
(similar to EF Eri) which are likely to contain brown dwarfs.
In the near-IR (JHK bands), interacting binaries with magnetic white
dwarfs can create complex spectral energy distributions (SED). The
accretion flux can often be observed in the near-IR. In addition, the
high magnetic fields (30MG) typical of polars can also contribute heavily
in the near -IR in the form of cyclotron humps. These humps are most
prominent in the 6000 Angstrom to 2.5 micron range. To complete the
SED or spectral picture of these interacting binaries, the longer
wavelength IR needs to be added. The mass donor (whether an M star
or brown dwarf) will radiate into the IR and should be clearly
identifiable at wavelengths longer than those possibly contaminated.
By using the Spitzer Infrared Array Camera (IRAC) the SED of the mass
donor star can be isolated and the spectral type can be determined.
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Lead Teacher:
Howard T. Chun
Cranston High School East
Cranston, RI
Participating Teachers:
Linda Stefaniak
Allentown High School, Allentown, NJ
Beth Thomas
East Middle School,
Great Falls, MT
Support Scientists:
Dr. Steve Howell
National Optical Astronomical Observatory, Tucson, AZ
Dr. Don Hoard
Spitzer Science Center, Pasadena, CA
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Proposal News
Work Summary:
October 2005
September 2005
August 2005
July 2005
May 2005 - pdf file
April 2005 - pdf file
March 2005 - pdf file
Proposal - pdf file
AOR - pdf file
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Proposed Observation Time:
IRAC Mapping (3.5 m, 4.5 m, 6.3 m, and 8.0 m)
Combine with optical and 2 MASS.
Use the SED to determine the mass of the donor star (M class, brown dwarf???)
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2MASS Name |
Period (min) |
K |
IRAC Exposures per wavelength (sec) |
Total Duration (sec) |
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V347 Pav |
90.1 |
14.985 |
150 (5x30) |
649 |
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GG Leo |
79.8 |
14.635 |
60 (5x12) |
468 |
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J0153.9-5948 |
89.0 |
15.149 |
150 (5x30) |
649 |
Status:
All of the group's objects have been observed and are in the archives. GG Leo and AAVSO 0150-60 (J0153.9-5948) have been reduced and
are being analyzed. V347 Pav was released on September 2 and has not yet been reduced.
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