J/A+A/689/A262      APT photometry for V889 Her and LQ Hya        (Tuomi+, 2024)

Characterising the stellar differential rotation based on largest-spot statistics from ground-based photometry. Tuomi M., Lehtinen J.J., Henry G.W., Hackman T. <Astron. Astrophys. 689, A262 (2024)> =2024A&A...689A.262T 2024A&A...689A.262T (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry, UBV Keywords: methods: statistical - stars: activity - stars: individual: V889 Her - stars: individual: LQ Hya - stars: rotation - starspots Abstract: Stellar spot distribution has consequences on the observable periodic signals in long-time baseline ground-based photometry. We model the statistics of the dominating spots of two young and active Solar-type stars, V889 Her and LQ Hya, in order to obtain information on the underlying spot distribution, rotation of the star, as well as the orientation of the stellar axis of spin. By calculating estimates for spot-induced periodicities in independent subsets of photometric data, we obtain statistics based on the dominating spots in each subset, giving rise to largest-spot statistics accounting for stellar geometry and rotation, including differential rotation. Our simple statistical models are able to reproduce the observed distribution of photometric signals rather well. This also enables us to estimate the dependence of angular velocity of the spots as a function of latitude. Our results indicate that V889 Her has a non-monotonic differential rotation curve with a maximum angular velocity between latitudes of 37-40 deg and lower angular velocity at the pole than the equator. Our results for LQ Hya indicate that the star rotates much like a rigid body. Furthermore, the results imply that the monotonic Solar differential rotation curve may not be a universal model for other solar-type stars. The non-monotonicity of the differential rotation of V889 Her is commonly produced in magnetohydrodynamic simulations, which indicates that our results are realistic from a theoretical perspective. Description: The B- and V-band light curves for the stars V889 Her and LQ Hya are provided in the files v889her_b.dat, lqhya_b.dat, v889her_v.dat and lqhya_v.dat as differential photometry against the comparison stars HD 171286 (V889 Her) and HD 82477 (LQ Hya). The time points are given as reduced HJD, i.e. HJD-2400000.0. The data was obtained with the T3 0.4m APT at the Fairborn Observatory, Arizona. Objects: ------------------------------------------------------- RA (2000) DE Designation(s) ------------------------------------------------------- 18 34 20.1 +18 41 24.2 V* V889 Her = HD 171488 09 32 25.6 -11 11 04.7 V* LQ Hya = HD 82558 ------------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file lqhyab.dat 19 3730 LQ Hya B-band light curve lqhyav.dat 19 3653 LQ Hya V-band light curve v889herb.dat 19 2780 V889 Her B-band light curve v889herv.dat 19 2755 V889 Her V-band light curve -------------------------------------------------------------------------------- See also: J/A+A/276/345 : Photometry of variable LQ Hya (Jestu 1993) J/A+A/394/505 : UBV photometry of LQ Hya (Berdyugina+, 2002) J/A+A/542/A38 : LQ Hya V-band differential light curve (Lehtinen+, 2012) J/A+A/575/A57 : LQ Hya activity and Li variations (Flores Soriano+, 2015) J/A+A/577/A120 : Carrier fit analysis of LQ Hya photometry (Olspert+, 2015) J/A+A/660/A141 : Light curve of the active star LQ Hya (Lehtinen+, 2022) J/A+A/622/A170 : V-band differential photometry for V889 Her (Willamo+, 2019) Byte-by-byte Description of file: lqhya?.dat v889her?.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 F10.4 d HJD Reduced Heliocentric Julian Date (HJD-2400000) 13- 17 F5.3 mag dmag Differential band Johnson (B or V) photometry 19 A1 --- Band [BV] Observed band -------------------------------------------------------------------------------- Acknowledgements: Mikko Tuomi, mikko.tuomi(at)helsinki.fi Thoma Hackman, thomas.hackman(at)helsinki.fi
(End) Patricia Vannier [CDS] 02-Sep-2024
The document above follows the rules of the Standard Description for Astronomical Catalogues; from this documentation it is possible to generate f77 program to load files into arrays or line by line