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On the properties of very young massive infrared sources (Mitteilungen der Universitäts‐Sternwarte zu Jena Nr. 169)
Author(s) -
Gürtler J.,
Henning T. H.,
Dorschner J.,
Friedmann C.
Publication year - 1985
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.2113060605
Subject(s) - physics , astrophysics , maser , infrared , luminosity , silicate , ionization , outflow , young stellar object , stars , astronomy , star formation , galaxy , ion , quantum mechanics , meteorology
The data compiled for 34 very young massive compact infrared source (Becklin‐Neugebauer objects) in a separately published catalogue serve as the basis for an investigation of their general properties. First, the correlations of the strength of the ice and silicate bands at 3.1 μm and 10 μm, resp., with each other and with other parameters of the sources are investigated. In accordance with theoretical expectations the strengths of both bands are not well correlated with each other. The ratio τ 10 /τ 3 of their optical depths veries from 0.85 to 8 (and possibly up to 22). That implies for the number densities of the grains that (naked) silicate grains always are considerably more abundant than ice grains (grains with ice mantles). It follows from the discussion of the relationships between τ 10 , the temperature parameter of the sources, and their luminosity that relations between τ 10 and temperature and possibly between τ 10 and the luminosity exist. Stellar wind models for the ionized region around the embedded star are favoured after the analysis of the intensities of the hydrogen infrred emission lines and the radio continuum. The limited observational data do not yet allow a decision on a correlation between the silicate band depth and energy content and/or the velocity of the bipolar outflow detected in a number of sources. The BN objects are clearly more frequently associated with H 2 O masers than OH masers. The linear separations of the infrared peaks from the masers are compatible with models where the H 2 O masers are situated near the edges the gas‐dust shells of the BN objects.