Peculiar motions of OB associations and their associated molecular cloudsстатья
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Дата последнего поиска статьи во внешних источниках: 8 февраля 2017 г.
Аннотация:An analysis of radial-velocity data and the rotation curve constructed from Cepheid observations has revealed peculiar motions of 30 OB associations and their associated gas in a region within 3 kpc of the Sun. Streaming motions of the stars of the associations along the inner boundary of the Sagittarius–Carina arm against the Galactic rotation were detected. The radial velocity of the peculiar motions in this arm is Vres ~ 12 and 8 km s–1, depending on the adopted distance scale. In the Cygnus arm, streaming motions of the stars (with
velocity of 6 km s–1) and gas in the direction of the Sun are observed. Analysis of the effects of rotation curve, distance scale, and errors in the distances on the distribution of the radial velocity residuals of the associations gives consistent results everywhere, except for the region of the Perseus arm. Streaming motions of the molec-
ular clouds associated with the OB associations are considerably harder to distinguish than those of the stars of the associations. The derived distribution of the velocity residuals of the associations is generally consistent with the predictions of the density-wave theory. It is shown that the short distance scale of the associations, equal to 0.8 that of Blaha and Humphreys (1989), is in better agreement with the Cepheid distance scale.