SIMBAD references

1998A&A...330..559O - Astronomy and Astrophysics, volume 330, 559-568 (1998/2-2)

MgII h&k line diagnostics of IM Pegasi.

OLAH K., MARIK D., HOUDEBINE E.R., DEMPSEY R.C. and BUDDING E.

Abstract (from CDS):

We have analysed the MgII h&k resonance lines of IM Peg (KII-III) on 14 high resolution IUE LWR spectra and compared the results coming from visual spectroscopic and UBV(RI)C photometric data. The `clean' spectra (free from interstellar absorption) were modelled using a convolution of the rotational profile with a Gaussian profile, that represents macroturbulence and broadenings of other origin, the former dominating. Significant variations in the h&k line fluxes and widths were found throughout the orbital phase range. A line broadening effect is found at maximum spot visibility both in the k and h lines. The MgII line widths increase linearly with the flux of the transition region lines as a function of rotational phase. Anticorrelations as a function of phase were found between the MgII line fluxes and the higher temperature lines. The k line is broader than the h line, correlated with a slope greater than unity, in keeping with a greater radiation transfer effect in the k line, and a non-optically thin medium at all phases. We observe a systematic asymmetry in the ratio of the h to k line profiles at all phases. The spectral diagnostics thus suggest the appearance of a plage region on the stellar disc. We obtained new orbital elements of the IM Peg system, deriving a small, but non-zero eccentricity.

Abstract Copyright:

Journal keyword(s): stars: individual: IM Peg - stars: activity - stars: chromospheres - stars: binaries: spectroscopic - stars: late-type

Simbad objects: 8

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