共查询到3条相似文献,搜索用时 0 毫秒
1.
D. J. Lennon Paolo A. Mazzali F. Pasian P. Bonifacio V. Castellani 《Space Science Reviews》1993,66(1-4):169-172
Medium resolution (2A/px) but high s/n spectra of approximately twenty of the brightest blue stars in the young open cluster NGC 330 in the SMC have been analyzed in order to determine their atmospheric parameters and the evolutionary status. Stellar parameters are determined by comparison with LTE and NLTE model atmosphere calculations and an HR diagram constructed. Luminosities of the sample stars lie in the range 4.0L
*/L
)<5.0 and spectral types between O9 and late-B. The stars in our sample appear to define 4 groups: main-sequence B-stars (B2-B4), B-supergiants (B4) in a blue-loop phase of evolution, a small number of blue stragglers (O9-B0 near main-sequence stars) and a group of luminous giants (B1-B2) which reside in the so-called post main-sequence gap of the HR diagram. Furthermore, we have confirmed spectroscopically the very high incidence of Be stars in this cluster. Finally the almost complete absence of metal lines (at this resolution) is in keeping with the expected very low metallicity of the SMC. 相似文献
2.
Brunella Nisini Anlaug Amanda Kaas Ewine F. Van Dishoeck Derek Ward-Thompson 《Space Science Reviews》2005,119(1-4):159-179
We summarize the observations of the Infrared Space Observatory (ISO) concerning the earliest stages of the stellar formation.
The observations of samples of sources in different evolutionary stages are reviewed, addressing in particular how the physical
and chemical properties of the protostellar environments change from the pre-stellar cores to the protostars at the end of
their accretion phase. In addition, the mid-IR surveys in nearby star-forming regions are discussed, showing their implications
for the understanding of the stellar initial mass function.
Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries:
France, Germany, The Netherlands, and the United Kingdom), and with the participation of ISAS and NASA. 相似文献