The relative lens-source proper motion in MACHO 98-SMC-1

MD Albrow*, JP Beaulieu, JAR Caldwell, DL DePoy, M Dominik, BS Gaudi, A Gould, J Greenhill, K Hill, S Kane, R Martin, J Menzies, KR Pollard, PD Sackett, KC Sahu, P Vermaak, R Watson, A Williams, RW Pogge

*Bijbehorende auteur voor dit werk

OnderzoeksoutputAcademicpeer review

49 Citaten (Scopus)

Samenvatting

We present photometric and spectroscopic data for the second microlensing event seen toward the Small Magellanic Cloud (SMC), MACHO 98-SMC-1. The lens is a binary. We resolve the caustic crossing and find that the source took 2 Delta t = 8.5 hr to transit the caustic. We measure the source temperature T-eff = 8000 K both spectroscopically and from the color, (V-I)(0) similar to 0.22. We find two acceptable binary-lens models. In the first, the source crosses the caustic at phi = 43 degrees.2 and the unmagnified source magnitude is I-s = 22.15. The angle implies that the lens crosses the source radius in time t* = Delta t sin phi = 2.92 hr. The magnitude (together with the temperature) implies that the angular radius of the source is theta* = 0.089 mu as. Hence, the proper motion is mu theta*/t* = 1.26 km s(-1) kpc(-1). For the second solution, the corresponding parameters are phi = 30 degrees.6, I-s = 21.81, t* = 2.15 hr, theta* = 0.104 mu as, and mu = theta*/t* = 2.00 km s(-1) kpc(-1). Both proper-motion estimates are slower than 99.5% of the proper motions expected for halo lenses. Both are consistent with an ordinary binary lens moving at similar to 75-120 km s(-1) within the SMC itself. We conclude that the lens is most likely in the SMC proper.

Originele taal-2English
Pagina's (van-tot)672-677
Aantal pagina's6
TijdschriftAstrophysical Journal
Volume512
Nummer van het tijdschrift2
StatusPublished - 20-feb-1999

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