AAS 206th Meeting, 29 May - 2 June 2005
Session 40 Binary Stars
Poster, Wednesday, 10:00am-7:00pm, Thursday, 9:20am-2:00pm, June 1, 2005, Ballroom A

Previous   |   Session 40   |   Next

[40.08] A Preliminary Study of the Cool Dwarf Interacting Eclipsing Binary, HH95-79

R. T. McKenzie Jr., R.G. Samec, N.C. Hawkins (Bob Jones University), D.R. Faulkner (University of South Carolina, Lancaster), W. Van Hamme (Florida International Univeristy)

We present light curve and periodicity analyses for the late dwarf interacting binary, HH95-79. The bulk of our CCD observations were taken at the Southeastern Association for Research in Astronomy (SARA) observatory on Kitt Peak on 7, 8 December in 2004 and 21, March 2005 in remote mode by RGS, RM and NCH with the 0.9-m reflector using the the AP7 CCD. NCH and DRF observed one secondary minima at the National Undergraduate Research Observatory (NURO) in Flagstaff, AZ on March 11, on the 0.81-m Lowell reflector. Standard UBVRcIc filters were used throughout.

HH95-79 [GSC 1874 399, \alpha(2000)= 5h 48m 03.85s, \delta(2000)= +28\arcdeg 30\surd 47.6"] was discovered by Robertson et al. (IBVS #5536 2004). Its light curve shows primary and secondary eclipse depths are 1.0 and 0.3 magnitudes in V, respectively, so it is probably not in contact. With a period of only 0.25 days, the components of the system are likely late type dwarf stars. The comparison star was [GSC 2336 0621, \alpha(2000)= 05h 48m 10.29s, \delta(2000)= +28\arcdeg 27\surd 34.00.4"]. Over 100 observations in each of the BVRI pass bands were taken along with a few in U. Calibrations were done with AIPWIN by RM. Four mean epochs of minimum light were computed: HJD Min I = 2453348.7476 (±0.0011) and 2453349.0008 (±0.0027), and HJD Min II = 2453347.8687(±0.0015), 2453348.8715(±0.0013). The period behavior of the system is presently unclear but the following the linear ephemeris was calculated:

HJD Tmin I = 2453348.74775 (± 0.00053) + 0.25073181 (± 0.00000056) d*E.

Two B,V,R simultaneous synthetic light curve solutions were calculated, one semidetached and one contact. The semidetached model gave the primary, more massive component filling its Roche lobe (V1010 Oph type) while the secondary component filled 99% of its associated critical potential surface. The computed mass ratio, M2/M1, is 0.45 while the temperature difference T1-T2 is 1020 K (Our preliminary estimate is K5 and M2 for the spectral types for star 1 and star 2, respectively.) An inclination of 85.4\arcdeg was computed. A bief total eclipse occurs in the secondary eclipse. A superluminous region was found at a longitude of 278\arcdeg, a colatitude of 90\arcdeg with radius of 11\arcdeg and a temperature of 1.62 times that of the photosphere. This is probably a stream spot occuring as a result of the system coming into contact. A B,V,R contact solution is also presented. Both curves provide good fits to the curves. Although the contact solution gives slightly better residuals for the curves, we believe that the system is in its final stages of precontact.

Acknowledgements: We wish to thank the Southeastern Association for Research in Astronomy (SARA) and the National Undergraduate Research Observatory (NURO) for allocation of observing time, as well as NASA and the American Astronomical Society for their continued support of our undergraduate research programs through their small research grants.

Previous   |   Session 40   |   Next

Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.