The First Spectroscopic Observations of Caustic Crossing in a Binary Microlensing Event

Details The First Spectroscopic Observations of Caustic Crossing in a Binary Microlensing Event The First Spectroscopic Observations of Caustic Crossing in a Binary Microlensing Event

Nov 1996

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996apj...471l..23l&link_type=abstract

Astrophysical Journal Letters v.471, p.L23

Astronomy and Astrophysics

Astronomy

41

Cosmology: Dark Matter, Galaxy: Center, Cosmology: Gravitational Lensing, Stars: Abundances, Stars: Late-Type

Scientific paper

We present the first spectroscopic observations of a binary microlensing event when it was undergoing a caustic crossing with a high magnification of A ~ 25. The event 96-BLG-3 was identified in real time by the MACHO collaboration, in the Baade's window field toward the Galactic bulge. Three spectra were taken consecutively, spanning the light-curve peak of the caustic crossing, each integration lasting 30 minutes. The spectrograms covered the wavelength range 3985--6665 A and are almost identical, the third one differing only in having an amplitude ~6% lower than the others. By comparison with reference star spectra and by using spectrum synthesis techniques, we infer that the source star is a G0 IV--V star, with an effective temperature of Teff +/- 150 K, a metallicity in the range [M/H] = +0.3 to +0.6, and a logarithmic surface gravity of log g = 4.25 +/- 0.25. Using theoretical evolutionary tracks, we derive a radius of ~1.4 ^{-0.4}_{+0.6} Rsolar and hence a distance of 6.9 ^{-1.7}_{+3.1} kpc, consistent with the source residing in the Galactic bulge. We also determine its heliocentric radial velocity to be vr +/- 3 km s-1. Caustic-crossing microlensing events such as 96-BLG-3, if they are observed with 8--10 m class telescopes, can resolve the stellar surface of distant sources with a resolution of 1010 cm or better. This permits a detailed study of the center-to-limb variation of the stellar surface and the intrinsic properties of the lensed source.

Affiliated with

Also associated with

No associations

Rating

The First Spectroscopic Observations of Caustic Crossing in a Binary Microlensing Event does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The First Spectroscopic Observations of Caustic Crossing in a Binary Microlensing Event, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The First Spectroscopic Observations of Caustic Crossing in a Binary Microlensing Event will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1146430