SIMBAD references

2018MNRAS.473.4055M - Mon. Not. R. Astron. Soc., 473, 4055-4063 (2018)

The SMC B-type supergiant AzV322: a g-mode pulsator with a circumstellar disc.

MENNICKENT R.E., KOLACZKOWSKI Z., SOSZYNSKI I., CABEZAS M. and GARRIDO H.E.

Abstract (from CDS):

We present a photometric and spectroscopic study of AzV322, an emission line object located in the Small Magellanic Cloud previously classified between O9 and B0. We analyse 17.5 yr of I- and V-band OGLE-II, -III and -IV light curves and find four significant frequencies, viz. f1 = 0.386 549 ± 0.000 003, f2 = 0.101 177 ± 0.000 005, f3 = 0.487 726 ± 0.000 015 and f4 = 0.874 302 ± 0.000 020 cycles d-1 . The f1 frequency (period 2.587 00 ± 0.000 02 d) provides the stronger periodogram peak and gives a single wave light curve of full amplitude 0.066 mag in the I band. High-resolution optical spectroscopy confirms the early B-type spectral type and reveals prominent double peak Balmer, Paschen, O I 8446 and He I 5875 emissions. The spectral energy distribution shows significant colour excess towards long wavelengths possibly attributed to free-free emission in a disc -like envelope. Our analysis yields Teff = 23 000 ± 1500 K, log g = 3.0 ± 0.5, M = 16 ± 1 M☉, R = 31.0 ± 1.1 R☉ and Lbol = 104.87 ± 0.06 L☉. AzV322 might be a member of the new class of slowly pulsating B supergiants introduced by Saio et al. and documented by Lefever, Puls & Aerts; however its circumstellar disc makes it an hither to unique object. Furthermore, we notice that an O-C analysis for f1 reveals quasi-cyclic changes for the times of maximum in a time-scale of 20 yr, which might indicate a light-travel time effect in a very wide orbit binary with an undetected stellar component.

Abstract Copyright: © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): stars: early-type - stars: emission-line, Be - stars: evolution - stars: mass-loss - supergiants - stars: variables: general

Simbad objects: 5

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