Journal or Publication Title:

Բյուրականի աստղադիտարանի հաղորդումներ: Երևանի աստղադիտարանի բյուլետեն = Сообщения Бюраканской обсерватории. Бюллетень ереванской Астрономической обсерватории = Contributions from the Burakan observatory. Bulletin of the Erevan astronomical observatory

Date of publication:

2025

Volume:

72

Number:

1

ISSN:

2579-2276

Coverage:

78-83

Abstract:

Context: The Kepler mission spent 9 years discovering exoplanets; however, it also provided valuable information not only about these objects but also more than 200,000 light curves of active stars. From this data, we can measure stellar characteristics such as rotation period and differential rotation.// Aims: Our main goal is to measure differential rotation (DR) using two methods. The first is the ”Two-Peak Method,” developed by Reinhold & Gizon (2015). Their research provided a formula that calculates the DR coefficient based on the difference between the periods of two peaks that are close to each other. The formula (Phigh-Plow)/ Phigh gives the DR parameter, where Phigh and Plow represent periods at higher and lower latitudes, respectively. A positive coefficient indicates solar-like differential rotation, while a negative coefficient indicates anti-solar differential rotation. The second method is the ”Gaussian Distribution Function Method,” which assumes that the full width at half maximum (FWHM) of the periodogram’s Gaussian distribution can be an indicator of the star’s differential rotation. Method: We used the Kepler database (Q0-Q17 quarters) to derive differential rotation for 25,000 F G K M spectral-class stars using the two methods described above. We analysed their light curves using the Lomb-Scargle periodogram. Results: In our research, we identified differential rotation in 500 stars using the “Two-Peak Method” and in 200 stars (with 10 solar-like effective temperature, radius, and rotation period stars) using the “Gaussian Distribution Function Method”. From the first one, we found ∼ 10% asymmetry between solar and anti-solar differential rotation. For these 500 stars, DR was measured for the first time in almost 300 stars. We also present the statistical characteristics (rotation period, temperature, radius, log g, and mass) of these stars in relation to the differential rotation coefficient.

Format:

pdf

Identifier:

oai:arar.sci.am:425916

General note:

Communications of the Byurakan Astrophysical Observatory (ComBAO) is a peer-reviewed scientific journal, which publishes research in observational and theoretical astronomy/astrophysics and presents recent advances in these fields. It is being published by the NAS RA V. Ambartsumian Byurakan Astrophysical Observatory (BAO) in English in electronic form. The journal publishes original papers, review papers, brief reports, book reviews, special communications, observational and theoretical results in various fields of astronomy and related sciences, and some editorial notes, including anniversaries and obituaries. Under the heading “Legacy”, the renewed magazine will republish some old articles of high value in English. The heading “Guest articles” will bring to the attention of readers the articles of researchers who are not employees of BAO. ComBAO was founded in 1946 and regularly published in 1946-1990. However, the publication was interrupted because of the economic situation after the disintegration of the Soviet Union in 1991.

Location of original object:

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