STScI Preprint #1218

New Distance Determination to the LMC

Using the new reductions of the IUE light curves by Sonneborn et al (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ring R_abs = (6.23±0.08) ×10¹⁷ cm and an angular size R" = 808±17 mas, which give a distance to the supernova d(SN 1987A) = 51.4±1.2 kpc and a distance modulus m-M(SN 1987A)=18.55±0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to be d(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus of m-M(LMC)=18.58±0.05. Revising accordingly the zero point of the Cepheid distance scale, and using the SNIa measured by Sandage and collaborators, one finds a value of the Hubble constant H₀ = 60±6 km s^-1 Mpc^-1.

Status:

Appeared in: Mem. Soc. Astron. Ital. 69: 225-235, 1998
(the proceedings of the Workshop Views on Distance Indicators, held 3-6 September 1997 in Sant'Agata sui Due Golfi, Italy)

Affiliations:

Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
On assignment from the Astrophysics Division, Space Science Department of ESA