Line-depth and Teff variations with the solar cycle

Details Line-depth and Teff variations with the solar cycle Line-depth and Teff variations with the solar cycle

Mar 2002

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002esasp.477..205c&link_type=abstract

In: Proceedings of the Second Solar Cycle and Space Weather Euroconference, 24 - 29 September 2001, Vico Equense, Italy. Editor:

Computer Science

Solar Activity Cycles, Effective Temperatures

Scientific paper

We show that the sensitivity of line-depth ratios, used as indicators of Teff variations (δTeff = C0δr/r), are sensibly dependent on surface gravity. We propose a theoretical calibration, including a careful treatment of the convective transport and its dependence on surface gravity (Canuto & Mazzitelli, 1991; Ludwig et al. 1999), which fits very well the stellar observations by Gray & Livingston (1997) of the same lines monitored at Kitt Peak since 1976 (C I 538.032 nm, Fe I 537.958 nm and Ti II 538.103 nm). The immediate consequence is the impossibility of applying the empirical calibration used by Gray & Livingston (1997) to interpret the line variations with the solar cycle, because it was derived from stars of different surface gravity, while in the solar case the value of g remains practically constant. Using our theoretical values of C0, we obtain a Teff variation too large, which would produce almost twice the measured variation of irradiance. However, as already showed by Caccin & Penza (2000), a simultaneous variation of the granulation size of the order of that observed (Muller & Roudier, 1984) might compensate for this excess. Therefore the observed variations of line-depth ratios with the solar cycle might be consistent with a dominant contribution of bright & dark magnetic regions to the total irradiance variations.

Affiliated with

Also associated with

No associations

Rating

Line-depth and Teff variations with the solar cycle does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Line-depth and Teff variations with the solar cycle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Line-depth and Teff variations with the solar cycle will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-780152