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Period–luminosity relations for red supergiant variables – II. The distance to M101 |
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| Authors: | J S Jurcevic M J Pierce G H Jacoby |
| Institution: | Astronomy Department, University of Texas, Austin, TX 78712, USA; Astronomy Department, Indiana University, Bloomington, IN 47405, USA; Kitt Peak National Observatory, National Optical Astronomy Observatories, P.O. Box 26732, Tucson, AZ 85726, USA |
| Abstract: | We report the discovery of 42 red supergiant variables (RSVs) in the late-type spiral galaxy M101. Periods for the luminosity variation of these RSVs were determined from 20 epochs of ground-based CCD photometry in the Kron–Cousins R band obtained with the KPNO 2.1-m and WIYN 3.5-m telescopes over a span of three years. The periods found were in the range 200–1300 days. Using the relationship between the RSV periods and their luminosity in the Kron–Cousins I band, we estimate a reddening-corrected distance modulus to M101 of 29.40±0.16 mag (based on a distance modulus of 18.5±0.1 mag for the Large Magellanic Cloud). This distance is consistent with the Hubble Space Telescope Key Project Cepheid distances of 29.34±0.17 mag for the outer field of M101 and 29.21±0.17 mag for the inner field. |
| Keywords: | supergiants stars: variables: other galaxies: distances and redshifts galaxies: individual: M101 |