The HeI6678 line in P Cyg
Posted: Tue Sep 27, 2011 7:08 am
Beside of the primary aim of the P Cyg campaign, I studied the behavior of the HeI6678 line, which represents the helium-forming zone (12-13 stellar radii; O. Chesneau et al., ASP Conf. Ser., 233, 2001), near the central star (see attached pdf file).
A series of 76 HeI6678 spectra, obtained during April 2003 until today, shows fig.1. It shows clear the variations in the emission intensity, variations of the central absorption core and its movement in wavelength. The correlation of the emission intensity and the central absorption core is obvious (fig.2). This is due of variability of optical depth, as result of a variability in mass-loss.
Two spectra (JD 2455767 & 2455675) in fig. 3 shows the measured maximum difference so far in expansion velocity of approx. 40 km/s. This is qualitatively in good agreement with Markova 1993 (A&A, 273, 555).
From JD 2555444 until now the central absorption core is variable in a quasi-periodic way (fig. 4). A period analysis of this time section (fig. 5 & 6) reveals a period of 158 d.
As far as I know, is this the first time, that the central absorption core of HeI6678 in P Cyg does show this sort of quasi-periodic variability.
Ernst Pollmann
-------------------------------------------------
Active Spectroscopy in Astronomy
http://www.astrospectroscopy.de
A series of 76 HeI6678 spectra, obtained during April 2003 until today, shows fig.1. It shows clear the variations in the emission intensity, variations of the central absorption core and its movement in wavelength. The correlation of the emission intensity and the central absorption core is obvious (fig.2). This is due of variability of optical depth, as result of a variability in mass-loss.
Two spectra (JD 2455767 & 2455675) in fig. 3 shows the measured maximum difference so far in expansion velocity of approx. 40 km/s. This is qualitatively in good agreement with Markova 1993 (A&A, 273, 555).
From JD 2555444 until now the central absorption core is variable in a quasi-periodic way (fig. 4). A period analysis of this time section (fig. 5 & 6) reveals a period of 158 d.
As far as I know, is this the first time, that the central absorption core of HeI6678 in P Cyg does show this sort of quasi-periodic variability.
Ernst Pollmann
-------------------------------------------------
Active Spectroscopy in Astronomy
http://www.astrospectroscopy.de