63 citations · 309 across the 28 of their papers we have counts for
28 papers
Six decades of TIGRE and Mount Wilson chromospheric monitoring in the H and K lines: The quest for an understanding of solar-type activity
J. H. M. M. Schmitt, K. -P. Schröder, M. Mittag +3
The combined time series of the consistently calibrated chromospheric activity indicator, the S-index -- derived from Mount Wilson and TIGRE data -- now spans more than five decade…
On the stellar parameter dependence of the combined Fe I and Fe II chromospheric emission-line in the wings of the Ca II K line
Faiber Rosas-Portilla, Luis Zapata, Klaus-Peter Schröder +3
We present an analysis of the chromospheric emission of Fe I + Fe II in the wing of the Ca II K line of 21 G and K giant stars. Stellar parameters and absolute chromospheric fluxes…
Bright Spectroscopic Binaries: III. Binary systems with orbital periods of P > 500 days
Dennis Jack, Missael Alejandro Hernández Huerta, Faiber Danilo Rosas-Portilla +1
We present an analysis of nine bright spectroscopic binaries (HD 1585, HD 6613, HD 12390, HD 39923, HD 55201, HD 147430, HD 195543, HD 202699, HD 221643), which have orbital period…
Chromospheric activity and photospheric variation of Ori during the great dimming event in 2020
M. Mittag, K. -P. Schröder, V. Perdelwitz +2
The so-called great dimming event of alpha Ori in late 2019 and early 2020 sparked our interest in the behaviour of chromospheric activity during this period. To study the timeline…
Eight years of TIGRE robotic spectroscopy: Operational experience and selected scientific results
J. N. González-Perez, M. Mittag, J. H. M. M. Schmitt +4
TIGRE (Telescopio Internacional de Guanajuato Robótico Espectroscópico) has been operating in fully robotic mode in the Observatory La Luz (Guanajuato, Mexico) since the end of 201…
On the physical nature of the Wilson-Bappu effect: revising the gravity and temperature dependence
F. Rosas-Portilla, K. -P. Schröder, D. Jack
We present a sample of 32 stars of spectral types G and K, and luminosity classes I to V, with moderate activity levels, covering four orders of magnitude of surface gravity and a…