C.D.S. - SIMBAD4 rel 1.7 - 2020.11.25CET09:44:12

2013A&A...557A..11R - Astronomy and Astrophysics, volume 557A, 11-11 (2013/9-1)

Fast and reliable method for measuring stellar differential rotation from photometric data.


Abstract (from CDS):

Co-rotating spots at different latitudes on the stellar surface generate periodic photometric variability and can be useful proxies for detecting differential rotation (DR). This is a major ingredient of the solar dynamo, but observations of stellar DR are very sparse. Because the Kepler space telescope steadily collects more data, we are interested in detecting DR using photometric information of a star. The main goal of this paper is to develop a fast method for determining stellar DR from photometric data. We ran an extensive Monte Carlo simulation of differentially rotating spotted stars with very different properties to investigate the detectability of DR. For different noise levels the resulting light curves were prewhitened using Lomb-Scargle periodograms to derive parameters for a global sine fit to detect periodicities. We show under which conditions DR can successfully be detected from photometric data, and in which cases the light curve provides insufficient or even misleading information on the stellar rotation law. In our simulations, the most significant period P1out is on average 2.4% shorter than the actual spot rotation-rate. This period was detected in 96.2% of all light curves. The signature of DR is a second period close to P1out in our model. For the noise-free case, we found such a period in 64.2% of all stars. Calculating the measured latitudinal shear of two distinct spots αout, and comparing this with the known original spot rotation-rates shows that the real value is on average 3.2% lower. Comparing the total equator-to-pole shear α to αout, we find that α is underestimated by 8.8%, especially the detection of DR for stars with α<6% is challenging. Finally, we applied our method to four differentially rotating Kepler stars and found close agreement with results from detailed modeling. The method we developed is capable of measuring stellar rotation periods and detecting DR with relatively high accuracy and is suitable for large data sets. We will apply our analysis to more Kepler data in a forthcoming paper.

Abstract Copyright:

Journal keyword(s): stars: rotation - starspots - methods: analytical - methods: statistical - techniques: photometric

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
1 * eps Eri BY* 03 32 55.8449634 -09 27 29.731165 5.19 4.61 3.73 3.00 2.54 K2V 1720 1
2 V* LQ Hya BY* 09 32 25.5684079124 -11 11 04.687410738 9.316 8.761 7.891 7.288 6.815 K1Vp 405 0
3 RX J1925.0+4429 Ro* 19 25 02.0048126 +44 29 50.757778   10.83 9.93 9.595   K1V 34 0
4 KIC 5110407 BY* 19 39 19.9395282541 +40 14 26.588296512     16.900 16.390   ~ 8 0
5 TYC 3148-2163-1 Ro* 19 42 50.5787960349 +43 24 48.662472426     11.736 11.51 10.986 G2V 17 0
6 HD 189210 Ro* 19 56 59.7430162616 +43 45 08.300363883   10.58 9.98   9.240 G1.5V 24 0

    Equat.    Gal    SGal    Ecl

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