Ref Arxiv: 1903.12163
Ref. & Cit.: NASA ADS
Commentaires: 10 pages, 12 figs, 3 Tables. Accepted for publication by AA

Ref Arxiv: 1901.11427
Ref INSPIRE: 1735542
DOI: 10.1007/s10511-019-09574-7
Ref. & Cit.: NASA ADS
Commentaires: 8 pages, 4 figures, accepted to Astrophysics

DOI: 10.1007/s10511-018-9539-4

Ref HAL: hal-01983689_v1
Ref INSPIRE: 1954238
DOI: 10.1007/s10511-018-9517-x
Exporter : BibTex | endNote
Commentaires: SPRINGER has Copyright

Résumé:

IRC+10216 is the nearest carbon star with a very high mass-loss rate. The existence of a binary companion has been hinted at by indirect observational evidence, such as the bipolar morphology of its nebula and a spiral-like pattern in its circumstellar material; however, to date, no companion has been identified. We have examined archival Hubble Space Telescope images of IRC+10216, and find that the images taken in 2011 exhibit dramatic changes in its innermost region from those taken at earlier epochs. The scattered light is more spread out in 2011. After proper motion correction, the brightest peak in 2011 is close to, but not coincident with, the dominant peak in previous epochs. A fainter point-like object was revealed at ∼0.″5 from this brightest peak. We suggest that these changes at the core of IRC+10216 are caused by dissipation of intervening circumstellar dust, as indicated by the brightening trend in the light curve extracted from the Catalina photometric survey. We tentatively identify the brightest peak in 2011 as the primary star of IRC+10216 and the fainter point-like source as a companion. The cause of non-detections of the companion candidate in earlier epochs is uncertain. These identifications need to be verified by monitoring the core of IRC+10216 at high resolution in the future.

DOI: 10.1007/s10511-015-9390-9
5 citations

Résumé:

The goal of this paper is to present an optical variability study of the comparatively faint carbon (C) stars which have been discovered by searching the First Byurakan Survey (FBS) low-resolution (lr) spectral plates at high Galactic latitudes using recent wide-area variability databases. The light curves from the Catalina Sky Survey (CSS) and Northern Sky Variability Survey (NSVS) databases were exploited to study theit variability nature. In this paper, first in this series, the variability classes are presented for 54 N-type Asymptotic Giant Branch (AGB) C stars. One finds that 9 stars belongs to the group of Mira-type, 43 are Semi-Regular (SR), and 2 stars are Irregular (Irr)-type variables. The variability types of 27 objects has been established for the first time. K-band absolute magnitudes, distances, and height from the Galactic plane were estimated for all of them. We aim to better understand the nature of the selected C stars through spectroscopy, 2MASS photometric colors, and variability data. Most of the tools used in this study are developed within the framework of the Astronomical Virtual Observatory.