J-band variability of M dwarfs in the WFCAM Transit Survey
We present an analysis of the photometric variability of M dwarfs in the Wide Field Camera (WFCAM) Transit Survey. Although periodic light-curve variability in low mass stars is generally dominated by photospheric star spot activity, M dwarf variability in the J band has not been as thoroughly investigated as at visible wavelengths. Spectral type estimates for a sample of over 200 000 objects are made using spectral type-colour relations, and over 9600 dwarfs (J <17) with spectral types later than K7 were found. The light curves of the late-type sample are searched for periodicity using a Lomb-Scargle periodogram analysis. A total of 68 periodic variable M dwarfs are found in the sample with periods ranging from 0.16 to 90.33 d, with amplitudes in the range of similar to 0.009 to similar to 0.115 in the J band. We simulate active M dwarfs with a range of latitude-independent spot coverages and estimate a periodically variable fraction of 1-3 per cent for stars where spots cover more than 10 per cent of the star's surface. Our simulated spot distributions indicate that operating in the J band, where spot contrast ratios are minimized, enables variability in only the most active of stars to be detected. These findings affirm the benefits of using the J band for planetary transit searches compared to visible bands. We also serendipitously find a Delta J > 0.2 mag flaring event from an M4V star in our sample.
Item Type | Article |
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Uncontrolled Keywords | stars: activity; stars: late type; stars: starspots; stars: variables: general; SKY SURVEY DATA; LOW-MASS STARS; SCALE MAGNETIC TOPOLOGIES; FIELD M-DWARFS; MONITOR PROJECT; MAIN-SEQUENCE; TIME-SERIES; SPACED DATA; COOL STARS; MID-M |
Date Deposited | 27 Jul 2024 00:05 |
Last Modified | 27 Jul 2024 00:05 |
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Read more research from the creator(s):
- Goulding, N. T.
- Barnes, J. R.
- Pinfield, D.J.
- Kovacs, G.
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- Catalan, S.
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- Jones, H.R.A.
- del Burgo, C.
- Jeffers, S.V.
- Nefs, S.
- Galvez-Ortiz, M. -C.
- Martin, E. L.
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