On the distance scale of the nearby classical cepheids.
Abstract
On the ground of new proper motions data, we have checked the distance scale of the Cepheids derived from the cluster Cepheid method, by applying the method of maximum likelihood (Jung, 1969), to a sample of 33 near-by Cepheids (r 1 kpc). Special attention has been paid to the determination of interstellar absorption. The corrections of extrinsic unreddening have been discussed. The method of maximum likelihood gives a systematic correction to the period-luminosity relation as given by Sandage and Tammann (1968), of about 0A (+ 0.4, standard deviation), after taking into account the bias caused by errors on the proper motions. It is stressed that the method of maximum likelihood could in principle give an accuracy of about 0.2, ff the sample were extended to all Cepheids closer than 2.3 kpc, provided the probable errors on the proper motions were known with sufficient accuracy.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 1970
- Bibcode:
- 1970A&A.....6..130J