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CURRENT TEAMS
New Teams Coming Soon!
+ Round 4
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Round 1 - Detecting Brown Dwarfs in
Interacting Cataclysmic Binaries
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Abstract
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.
Click on any teacher's name to see activities associated with NITARP.
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Lead Teacher:
Participating Teachers:
Support Scientists:
Dr. Steve Howell
National Optical Astronomical Observatory, Tucson, AZ
Dr. Don Hoard
Spitzer Science Center, Pasadena, CA
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Program News and Work
Proposal - pdf file
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Technical Details:
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) |
| V347 Pav |
90.1 |
14.985 |
150 (5x30) |
649 |
| GG Leo |
79.8 |
14.635 |
60 (5x12) |
468 |
| 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.
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