Four ultra-short-period eclipsing M-dwarf binaries in the WFCAM Transit Survey

Nefs, S. V.; Birkby, Jayne; Snellen, I. A. G.; Hodgkin, S. T.; Pinfield, D. J.; Sipőcz, Brigitta; Kovács, G.; Mislis, D.; Saglia, R.; Koppenhoefer, J.; Cruz, P.; Barrado, D.; Martín, E. L.; Goulding, N.; Stoev, H.; Zendejas, J.; Burgo, C. del; Cappetta, M.; Pavlenko, Ya. V.

doi:10.1111/j.1365-2966.2012.21338.x

Cited by 61 publications

(62 citation statements)

References 63 publications

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“…However, the red colors (V − I C ∼ 4.5; Mayne et al 2007) of HPer-513, indicative of a spectral type ∼M6, put this object far from expected pulsational instability strips at the age of the cluster (Rodríguez-López et al 2012;Baran et al 2011;Palla & Baraffe 2005). The shape of the phased light curve is somewhat suggestive of a contact binary (Nefs et al 2012) with…”

Section: Period Searchmentioning

confidence: 92%

The Monitor Project: stellar rotation at 13 Myr

Moraux

Artemenko

Bouvier

et al. 2013

A&A

115

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Aims. We aim at constraining the angular momentum evolution of low-mass stars by measuring their rotation rates when they begin to evolve freely towards the zero-age main sequence (ZAMS), i.e., after the disk accretion phase has stopped. Methods. We conducted a multisite photometric monitoring of the young open cluster h Persei, which has an age of ∼13 Myr. The observations were done in the I-band using four different telescopes, and the variability study is sensitive to periods from less than 0.2 day to 20 days. Results. Rotation periods are derived for 586 candidate cluster members over the mass range 0.4 ≤ M/M ≤ 1.4. The rotation period distribution indicates a slightly higher fraction of fast rotators for the lower mass objects, although the lower and upper envelopes of the rotation period distribution, located respectively at ∼0.2-0.3 d and ∼10 d, are remarkably flat over the whole mass range. We combine this period distribution with previous results obtained in younger and older clusters to model the angular momentum evolution of low mass stars during the pre-main sequence (PMS) phase. Conclusions. The h Per cluster provides the first statistically robust estimate of the rotational period distribution of solar-type and lower mass stars at the end of the PMS accretion phase (≥10 Myr). The results are consistent with models that assume significant core-envelope decoupling during the angular momentum evolution to the ZAMS.

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Section: Period Searchmentioning

confidence: 92%

The Monitor Project: stellar rotation at 13 Myr

Moraux

Artemenko

Bouvier

et al. 2013

A&A

115

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“…To be sensitive to small planets, MEarth observes a small number of stars with high photometric precision. Placing deeper constraints on the occurrence of Jupiter-sized planets can be better achieved by those surveys that monitor a larger number of M dwarfs, such as PTF/M-Dwarfs (Law et al 2012) or the WFCAM Transit Survey (Nefs et al 2012). …”

Section: Mearth Found No Jupiter-sized Exoplanetsmentioning

confidence: 99%

Constraints on Planet Occurrence Around Nearby Mid-to-Late M Dwarfs From the Mearth Project

Berta

Irwin

Charbonneau

2013

ApJ

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The MEarth Project is a ground-based photometric survey intended to find planets transiting the closest and smallest main-sequence stars. In its first four years, MEarth discovered one transiting exoplanet, the 2.7 R ⊕ planet GJ1214b. Here, we answer an outstanding question: in light of the bounty of small planets transiting small stars uncovered by the Kepler mission, should MEarth have found more than just one planet so far? We estimate MEarth's ensemble sensitivity to exoplanets by performing end-to-end simulations of 1.25 × 10 6 observations of 988 nearby mid-tolate M dwarfs, gathered by MEarth between 2008 October and 2012 June. For 2-4 R ⊕ planets, we compare this sensitivity to results from Kepler and find that MEarth should have found planets at a rate of 0.05-0.36 planets yr −1 in its first four years. As part of this analysis, we provide new analytic fits to the Kepler early M dwarf planet occurrence distribution. When extrapolating between Kepler's early M dwarfs and MEarth's mid-to-late M dwarfs, we find that assuming the planet occurrence distribution stays fixed with respect to planetary equilibrium temperature provides a good match to our detection of a planet with GJ1214b's observed properties. For larger planets, we find that the warm (600-700 K), Neptune-sized (4 R ⊕ ) exoplanets that transit early M dwarfs like Gl436 and GJ3470 occur at a rate of <0.15 star −1 (at 95% confidence) around MEarth's later M dwarf targets. We describe a strategy with which MEarth can increase its expected planet yield by 2.5 × without new telescopes by shifting its sensitivity toward the smaller and cooler exoplanets that Kepler has demonstrated to be abundant.

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“…Fortunately, the modern large stellar surveys during the last decade allowed to discover binaries with shorter and shorter periods Rucinski (2007), Pribulla et al (2009), Weldrake et al (2004, Maceroni & Rucinski (1997), Dimitrov & Kjurkchieva (2010), Norton et al (2011), Nefs et al (2012, Davenport et al (2013), Lohr et al (2014), Qian et al (2014), Drake et al (2014). The majority of the newly discovered binaries from space missions (Kepler, CoRoT, etc.)…”

mentioning

confidence: 99%