Astronomy and Astrophysics – Astrophysics
Scientific paper
1996-09-24
Astronomy and Astrophysics
Astrophysics
12 pages LaTeX with l-aa.sty and psfig.sty. Accepted for publication in Astronomy and Astrophysics
Scientific paper
Previous calculations of the rates and optical depths due to microlensing only considered resolved stars. However, if a faint unresolved star lens is close enough to a resolved star, the event will be seen by the microlensing experiments and attributed to the bighter star. The blending biases the duration, making the contribution of the unresolved stars very significant for short events. This contribution is confused with lensing by brown dwarfs. The exact rates of these blended events are extremly sensitive to the limiting magnitude achieved in the microlensing search. Appropriate calculations of the optical depth and rates are provided here, and illustrated in the case of the DUO and OGLE experiments. The additional contribution of unresolved stars is very significant and probably explains the high optical depth and rates observed towards the Galactic Bulge. The blended unresolved event can be identified using either the color shift or the light curve shape. However, neither of these two methods is apropriate to identify a large number of blended events towards the Bulge. In some cases of good photometry and small impact parameter, an identification is possible, as for the OGLE 5 event, which clearly appears as a case of lensing of an unresolved star. The recent results obtained by the PLANET collaboration indicate that a high resolution and dense sampling of the light curve is possible, and will probably provide a very interesting possibility to correct the blending bias, as demonstrated for OGLE 5. This possibility, is certainly better than a statistical estimation of the lensing rates, which are always prone to some uncertainty. But, at this time, the contribution of unresolved stars must be included in the analyses of microlensing experiments.
No associations
LandOfFree
Lensing of unresolved stars towards the Galactic Bulge 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 Lensing of unresolved stars towards the Galactic Bulge, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lensing of unresolved stars towards the Galactic Bulge will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-695488