The nature of the Kleinmann-Low and Becklin-Neugebauer infrared sources
Abstract
Polarization observations of the Becklin-Neugebauer IR point source, located within the Kleinmann-Low extended object, are analyzed. It is found that the polarization arises as radiation from BN passes through an ensemble of absorbing nonspherical oriented dust grains distributed on the periphery of KL. Two possibilities are considered for the nature of the two objects. First, it is proposed that BN is a protostar and KL is an early cluster of protostars (a contracting cloud of gas and dust) which radiates gravitational energy during its collapse. In this case, it is shown that the radiation from BN should not be polarized since supersonic accretion would take place on the periphery of KL, the dust could not be accelerated by collisions with gas particles on account of light pressure, and effective orientation of the dust grains on the periphery would be impossible. The other possibility is that KL is an optically thick dust cloud which contains hot O and B stars and which reradiates their energy in the IR. In this case, the dust grains would be oriented as a result of collisions and could cause noticeable polarization only in the presence of a transverse magnetic field of the same intensity as the interstellar field. The mass of the KL nebula is estimated to be of the order of 10,000 solar masses.
- Publication:
-
Astronomicheskii Zhurnal
- Pub Date:
- December 1975
- Bibcode:
- 1975AZh....52.1121G
- Keywords:
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- Infrared Astronomy;
- Interstellar Matter;
- Nebulae;
- Polarization Characteristics;
- Stellar Radiation;
- B Stars;
- Hot Stars;
- Interstellar Magnetic Fields;
- O Stars;
- Point Sources;
- Protostars;
- Star Clusters;
- Stellar Evolution;
- Astrophysics