Spectral classification of OB stars in both hemispheres and the absolute magnitude calibration.

1972 ◽  
Vol 77 ◽  
pp. 312 ◽  
Author(s):  
N. R. Walborn
Keyword(s):  
Absolute Magnitude ◽  
Spectral Classification ◽  
Ob Stars ◽  
The Absolute

scholarly journals Verification of the Spectral Classification of Stars Using the Hipparcos Catalogue

2014 ◽  
Vol 31 ◽  
Author(s):  
D. Deb ◽  
P. Chakraborty
Keyword(s):  
Absolute Magnitude ◽  
Interstellar Extinction ◽  
Statistical Technique ◽  
The Other ◽  
Spectral Classification ◽  
Intrinsic Nature ◽  
Hipparcos Catalogue ◽  
The Difference ◽  
Rule Out

AbstractThe spectral classifications of the stars from spectral data have been corrected from time to time and new spectral and luminosity classes have been assigned. Identifying stars with wrong spectral and luminosity classification has been a stupendous task from the huge catalogue of stars. In this work we describe a simple statistical technique to identify stars with wrong spectral and luminosity classification. We make use of the Hipparcos catalogue which has the most accurate measurement of the distance d of the stars. A comparison is made between the absolute V magnitudes MV computed using the observed V magnitude mV and d, with the standard absolute magnitude MV0 assigned to a spectral and luminosity classification for a large number of stars (with d < 100 pc). As expected, for most of the stars the difference between MV and MV0 lies within the range ±2 mag, due to the intrinsic nature of each star ignored in this generalisation. A systematic error analysis is made of all the observable used in the computation. Therefore to identify stars which we suspect to be wrongly classified, we look for abnormal deviation in |MV – MV0| ≥5. The location of these stars with respect to the galactic plain and interstellar extinction is also investigated to rule out effects due to variations in the interstellar extinction. From our results we see that some of the stars were indeed wrongly classified and have recently been reclassified (SIMBAD). The reclassification drastically reduces the |MV – MV0| deviation. The other stars in the list which have not yet been reclassified need to be spectroscopically investigated and classified again.

scholarly journals Infrared spectral classification of OB stars with ISO-SWS

2001 ◽  
Vol 366 (1) ◽  
pp. 241-253 ◽  
Author(s):  
P. A. Zaal ◽  
A. de Koter ◽  
L. B. F. M. Waters
Keyword(s):  
Spectral Classification ◽  
Ob Stars ◽  
Infrared Spectral

scholarly journals A new automated tool for the spectral classification of OB stars

2021 ◽  
Author(s):  
E. Kyritsis ◽  
G. Maravelias ◽  
A. Zezas ◽  
P. Bonfini ◽  
K. Kovlakas ◽  
...  
Keyword(s):  
Spectral Classification ◽  
Ob Stars ◽  
Automated Tool

scholarly journals The Wolf-Rayet Stars

1975 ◽  
Vol 67 ◽  
pp. 257-274
Author(s):  
Sergej V. Rublev
Keyword(s):  
Physical Properties ◽  
Absolute Magnitude ◽  
Stellar Systems ◽  
Spectral Classification ◽  
The Absolute

This review discusses the spectral classification, the absolute magnitude, the position in stellar systems, the physical properties and the evolution of WR stars.

scholarly journals New massive members of Cygnus OB2

2018 ◽  
Vol 612 ◽  
pp. A50 ◽  
Author(s):  
S. R. Berlanas ◽  
A. Herrero ◽  
F. Comerón ◽  
A. Pasquali ◽  
C. Bertelli Motta ◽  
...  
Keyword(s):  
Massive Stars ◽  
Spectral Classification ◽  
Homogeneous Population ◽  
B Stars ◽  
Ob Stars ◽  
Star Forming ◽  
Star Forming Regions ◽  
Close Distance ◽  
Galactic Longitude

Context. The Cygnus complex is one of the most powerful star forming regions at a close distance from the Sun (~1.4 kpc). Its richest OB association Cygnus OB2 is known to harbor many tens of O-type stars and hundreds of B-type stars, providing a large homogeneous population of OB stars that can be analyzed. Many studies of its massive population have been developed in the last decades, although the total number of OB stars is still incomplete. Aim. Our aim is to increase the sample of O and B members of Cygnus OB2 and its surroundings by spectroscopically classifying 61 candidates as possible OB-type members of Cygnus OB2, using new intermediate resolution spectroscopy. Methods. We have obtained intermediate resolution (R ~ 5000) spectra for all of the OB-type candidates between 2013 and 2017. We thus performed a spectral classification of the sample using HeI-II and metal lines rates, as well as the Marxist Ghost Buster (MGB) software for O-type stars and the IACOB standards catalog for B-type stars. Results. From the whole sample of 61 candidates, we have classified 42 stars as new massive OB-type stars, earlier than B3, in Cygnus OB2 and surroundings, including 11 O-type stars. The other candidates are discarded as they display later spectral types inconsistent with membership in the association. We have also obtained visual extinctions for all the new confirmed massive OB members, placing them in a Hertzsprung-Russell Diagram using calibrations for Teff and luminosity. Finally, we have studied the age and extinction distribution of our sample within the region. Conclusions. We have obtained new blue intermediate-resolution spectra suitable for spectral classification of 61 OB candidates in Cygnus OB2 and surroundings. The confirmation of 42 new OB massive stars (earlier than B3) in the region allows us to increase the young massive population known in the field. We have also confirmed the correlation between age and Galactic longitude previously found in the region. We conclude that many O and early B stars at B > 16 mag are still undiscovered in Cygnus.

Sign in / Sign up

Export Citation Format

Share Document