Title:

                Hubble Space Telescope Observations of the Large Magellanic Cloud Field around SN 1987A: Distance
                Determination with Red Clump and Tip of the Red Giant Branch Stars
 Authors:

                Romaniello, M.; Salaris, M.; Cassisi, S.; Panagia, N.
 Affiliation:

                AA(ESO, Karl-Schwarzschild-Straße 2, D-85748 Garching bei München, Germany; mromanie@eso.org),
                AB(Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf,
                Birkenhead CH41 1LD, UK; ms@staru1.livjm.ac.uk.; Max-Planck-Institut für Astrophysik,
                Karl-Schwarzschild-Straße 1, D-85748 Garching bei München, Germany), AC(Osservatorio Astronomico di
                Collurania, Via M. Maggini, 64100 Teramo, Italy; cassisi@astrte.te.astro.it.; Max-Planck-Institut für Astrophysik,
                Karl-Schwarzschild-Straße 1, D-85748 Garching bei München, Germany), AD(Space Telescope Science
                Institute, 3700 San Martin Drive, Baltimore, MD 21218; on assignment from the Astrophysics Division, Space
                Science Department of ESA; panagia@stsci.edu)
 Journal:

                The Astrophysical Journal, Volume 530, Issue 2, pp. 738-743.
 Publication Date:

                02/2000
 Origin:

                UCP
 ApJ Keywords:

                GALAXIES: DISTANCES AND REDSHIFTS, GALAXIES: INDIVIDUAL (LARGE MAGELLANIC
                CLOUD), STARS: EVOLUTION
 Abstract Copyright:

                (c) 2000: The American Astronomical Society
 Bibliographic Code:

                2000ApJ...530..738R


                                         Abstract

We have used Hubble Space Telescope (HST) WFPC2 multiband observations of a field around SN 1987A in the Large Magellanic Cloud to
measure its distance from the Sun. The observations allowed us to carefully determine the interstellar extinction along the line of sight to a
large number of stars and to measure the LMC distance by using two stellar distance indicators: the red clump (RC) and the tip of the red
giant branch (TRGB). From an application of the red clump method, we obtain a distance modulus of (m-M)LMC0,RC=18.59+/-0.04+/-0.08
mag (statistical plus systematic error), in good agreement with the distance derived by using the TRGB stars, namely,
(m-M)LMC0,TRGB=18.69+/-0.25+/-0.06 mag (statistical plus systematic error). Both values agree well with the distance to SN 1987A as
determined from a study of its inner ring fluorescent echo [(m-M)SN1987A=18.55+/-0.05 mag], thus excluding distance moduli lower than
18.43 to a 99.7% significance level. Differences with respect to previous results obtained using the same distance indicators are discussed.