Planetary transit mapping of spotted stars with Kepler

2011 ◽  
Author(s):  
Riley James Smith
Keyword(s):  
Spotted Stars

scholarly journals Twenty Years of Dedicated Photometry of RS CVn at Catania Observatory

1983 ◽  
Vol 71 ◽  
pp. 387-390
Author(s):  
C. Blanco ◽  
S. Catalano ◽  
E. Marilli ◽  
M. Rodonò
Keyword(s):  
Light Curves ◽  
Angular Rotation ◽  
Similar Activity ◽  
Activity Phase ◽  
Spotted Stars ◽  
Spotted Star ◽  
Complete Set ◽  
Star Rotation

We present a complete set of yearly seasonal light curves (LC) of RS CVn obtained from 1963 to 1982 at Catania Observatory, integrated with two LCs obtained by Ludington (1978) in 1975 and 1976. This unique observation set vividly shows (Figure l) the migrating outside of eclipse “photometric wave” (PW), which was first evidenced by Catalano and Rodonò (1967) and it is now considered the distinctive photometric feature of RS CVn binaries as well as of other spotted stars. By attributing the PW to surface inhomogeneities, or spots, whose visibility is modulated by the spotted star rotation, the present PW migration toward decreasing orbital phases indicates that the angular rotation of the KOIV spotted component is slightly lower than the orbital one. An inspection of Figure 1 readly shows that the almost sinusoidal PW has been fairly stable from 1963 up to 1981, when a double-peaked wave, still present in the 1982 LC, developed. Most probably the “unusual” 1949 LC by Keller and Limber (1951) and the 1976 one by Ludington (1978) were obtained at a similar activity phase.

scholarly journals Simulating acoustic waves in spotted stars

2015 ◽  
Vol 577 ◽  
pp. A145 ◽  
Author(s):  
Emanuele Papini ◽  
Aaron C. Birch ◽  
Laurent Gizon ◽  
Shravan M. Hanasoge
Keyword(s):  
Acoustic Waves ◽  
Spotted Stars

scholarly journals Synopsis of by Dra and II PEG Light Curves: Variability and Possible Evidence of Differential Rotation

1983 ◽  
Vol 71 ◽  
pp. 179-184 ◽  
Author(s):  
M. Rodonò ◽  
V. Pazzani ◽  
G. Cutispoto
Keyword(s):  
Differential Rotation ◽  
Binary Systems ◽  
Original Data ◽  
Light Curves ◽  
Time Interval ◽  
Photometric Variability ◽  
Spectroscopic Binary ◽  
Spotted Stars ◽  
Variable Light ◽  
Low Amplitude

BY Dra (MOVe+MOVe) and II Peg (K2IV-III) are well known noneclipsing spectroscopic binary systems showing the low-amplitude quasiperiodic photometric variability that is typical of spotted stars.Since the discovery of their variability (Chugainov 1966, Eggen 1968) additional accurate photometry has been carried out (cf. Rodono 1982). On account of their highly variable light curves (LC), we have reanalyzed all the available observations and divided the original data into shorter time-interval sets, so that overlapping LCs with different shape could be separated. Additional LCs obtained at Catania Observatory till 198l were also included.

scholarly journals Period determinations of spotted stars

2003 ◽  
Vol 407 (3) ◽  
pp. 1029-1037 ◽  
Author(s):  
D. Clarke
Keyword(s):  
Spotted Stars

scholarly journals Simulations of starspot anomalies within TESS exoplanetary transit light curves

2019 ◽  
Vol 630 ◽  
pp. A114 ◽  
Author(s):  
J. Tregloan-Reed ◽  
E. Unda-Sanzana
Keyword(s):  
Light Curve ◽  
Detection Limits ◽  
Mean Amplitude ◽  
Light Curves ◽  
Dwarf Stars ◽  
Spotted Stars ◽  
M Dwarf Stars ◽  
M Dwarf ◽  
The Relationship ◽  
Host Stars

Context. The primary targets of the NASA Transiting Exoplanet Survey Satellite (TESS) are K and M dwarf stars within our solar neighbourhood. Young K and M dwarf stars are known to exhibit a high starspot coverage (≈50%), however, older stars are known to show fewer starspots. This implies that TESS transit light curves at 2 min cadence may contain starspot anomalies, and if so, will require transit-starspot models to determine accurately the properties of the system. Aims. The goals are to determine if starspot anomalies can manifest in TESS transit light curves, to determine the detection limits of the starspot anomalies, and to examine the relationship between the change in flux caused by the starspot anomaly and the planetary transit. Methods. We conducted 20 573 simulations of planetary transits around spotted stars using the transit-starspot model, PRISM. In total 3888 different scenarios were considered using three different host star spectral types, M4V, M1V, and K5V. The mean amplitude of the starspot anomaly was measured and compared to the photometric precision of the light curve to determine if the characteristic “blip” of the starspot anomaly was noticeable in the light curve. Results. The simulations show that starspot anomalies are observable in TESS 2 min cadence data. The smallest starspot detectable in TESS transit light curves has a radius of ≈ 1900 km. The starspot detection limits for the three host stars are 4900 ± 1700 km (M4V), 13 800 ± 6000 km (M1V), and 15 900 ± 6800 km (K5V). The smallest change in flux of the starspot (ΔFspot = 0.00015 ± 0.00001) can be detected when the ratio of planetary to stellar radii k = 0.082 ± 0.004. Conclusions. The results confirm known dependencies between the amplitude of the starspot anomaly and the photometric parameters of the light curve. The results facilitated the characterisation of the relationship between the change in flux of the starspot anomaly and the change in flux of the planetary transit for TESS transit light curves.

scholarly journals Time series photometry and starspot properties

2010 ◽  
Vol 6 (S273) ◽  
pp. 104-110 ◽  
Author(s):  
Katalin Oláh
Keyword(s):  
Eclipsing Binaries ◽  
Special Focus ◽  
Flip Flop ◽  
Time Frequency ◽  
Cycle Lengths ◽  
Spotted Stars ◽  
Multiple Cycles ◽  
Activity Cycles ◽  
Term Monitoring

AbstractSystematic efforts of monitoring starspots from the middle of the XXth century, and the results obtained from the datasets, are summarized with special focus on the observations made by automated telescopes. Multicolour photometry shows correlations between colour indices and brightness, indicating spotted regions with different average temperatures originating from spots and faculae. Long-term monitoring of spotted stars reveals variability on different timescales.On the rotational timescale new spot appearances and starspot proper motions are followed from continuous changes of light curves during subsequent rotations. Sudden interchange of the more and less active hemispheres on the stellar surfaces is the so called flip-flop phenomenon. The existence and strength of the differential rotation is seen from the rotational signals of spots being at different stellar latitudes.Long datasets, with only short, annual interruptions, shed light on the nature of stellar activity cycles and multiple cycles. The systematic and/or random changes of the spot cycle lengths are discovered and described using various time-frequency analysis tools. Positions and sizes of spotted regions on stellar surfaces are calculated from photometric data by various softwares. From spot positions derived for decades, active longitudes on the stellar surfaces are found, which, in case of synchronized eclipsing binaries can be well positioned in the orbital frame, with respect to, and affected by, the companion stars.

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