H I shells and supershells

Journal Article · Sun Apr 15 04:00:00 EST 1979 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/156986· OSTI ID:5990288

Heiles, C

We present photographs of H I antenna temperatures in narrow velocity intervals versus galactic longitude and latitude, for the range 10/sup 0/< or =l< or =250/sup 0/, vertical-barbvertical-bar< or =10/sup 0/, derived from the Weaver and Williams survey. These photographs exhibit much filamentary structure. One has the impression that, if only the angular resolution were somewhat better, filamentary structure would appear even more prominently. Many of the filaments form portions of circular arcs. Some of these arcs change size with velocity in the manner expected for an expanding shell. In nearly all cases of such expanding shells only one hemisphere, either the approaching or the receding one, is apparent. The properties of 63 shells have been measured and tabulated.The H I shells do not seem to be significantly correlated with any other types of astronomical object, except perhaps yound stellar clusters. Shells range up to 1.2 kpc in radius, 2 x 10/sup 7/ M/sub sun/ in mass, and 10/sup 53/ ergs in kinetic energy. Their shapes tend to be circular, with a slight preference for elongation along the galactic plane. If the shells are produced by the injection of energy E/sub E/ into the interstellar medium by a sudden explosion such as a supernova, the required values of E/sub E/ range up to 6 x 10/sup 53/ ergs. This energy is hundreds of times larger than that available from a single supernova.Shells for which E/sub E/>3 x 10/sup 52/ ergs are deemed ''supershells'' because of their outstandingly large sizes and energy requirements. Supershells are not correlated with extreme Population I objects. The number of observed supershells is less than 10, a number which is consisent with a production rate of only 10/sup -7/ yr/sup -1/. The probability that the production agent has ever been directly observed is less than a few percent.

• Research Organization: Astronomy Department, University of California, Berkeley
• OSTI ID: 5990288
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 229:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics &amp; Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CONFIGURATION
COSMIC RADIO SOURCES
ENERGY
ERUPTIVE VARIABLE STARS
H1 REGIONS
INTERSTELLAR SPACE
KINETIC ENERGY
PHOTOGRAPHY
SPACE
STAR CLUSTERS
STARS
SUPERNOVAE
VARIABLE STARS