A Study of M-Type Stars in Cygnus.

Abstract

view Abstract Citations (45) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Study of M-Type Stars in Cygnus. Nassau, J. J. ; van Albada, G. B. Abstract The present investigation is based on objective-prism spectra taken with the 2° and 4° prisms attach- d to the 24-inch Schmidt-type telescope, with I-N emulsion and Wratten No. 89 filter. The classification of the M stars was established solely on the TiO bands, while the carbon stars were lentified from the bands of CN. A new band near X 7950 is utilized in the identification of S stars. A and in the same spectral region has been observed in several late M stars-notably variables. The miting magnitude for which we believe our data to be complete is 13.5 infrared, although a number of tars are classified down to 14.5. The search for M stars was carried out in a relatively clear region in Cygnus at galactic longitude 41 ?2 nd latitude 3~7. The area is in the form of a rectangle perpendicular to the celestial equator and covers .28 square degrees. In this area 709 M stars were identified, 4 carbon stars, ~and 2 S stars; of the total ye found several new variables. The number of M stars per square degree is 311, while at galactic latitude f 9~2 and approximately at the same longitude the corresponding number is 31. Infrared magnitudes were established by assuming that the infrared intrinsic color for an A5 star is qual to zero. The median apparent infrared magnitude of the MO stars at ga]actic latitude 3~7 is 13.1, ~hich value decreases with advancing spectral type to 11.3 at M4. This isin agreement with the absolute rifrared magnitudes derived from the Mount Wilson spectroscopic absolute magnitudes, which give - 1.2 or MO and -3.0 for M4. For the late M types this relation does not seem to exist, since the observed nedian magnitudes remain stationary after M4. From our material it was possible to obtain the spectrum-intrinsic color relation for all the M stars; hey are given in Table 2. An estimate of the interstellar absorption of the region was found to give ).1O mag. per kiloparsec (infrared). The unevenness in the surface distribution of M stars indicates local egions of much heavier obscuration. A density analysis has been made from 627 stars (M0-M4). At a distance of 2 kpc from the sun the iumber of stars is 16X 10-6 per cubic parsec and at a distance of 6 kpc, 8X 1O~. For 107 stars from M2.5 to V14 the corresponding values are 4X 10-6 and O.7x 10-6, respectively. In comparison, at a distance of 8 ~pc the density was found to be 0.1 X 10-6 or less Publication: The Astrophysical Journal Pub Date: May 1949 DOI: 10.1086/145144 Bibcode: 1949ApJ...109..391N full text sources ADS | data products SIMBAD (2) Related Materials (2) Erratum: 1949ApJ...110..104. Erratum: 1949ApJ...110..104N