J/ApJ/788/114 Detection of Kepler multiple M-star systems (Rappaport+, 2014)
M-dwarf rapid rotators and the detection of relatively young multiple M-star systems. Rappaport S., Swift J., Levine A., Joss M., Sanchis-Ojeda R., Barclay T., Still M., Handler G., Olah K., Muirhead P.S., Huber D., Vida K. <Astrophys. J., 788, 114 (2014)> =2014ApJ...788..114R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, M-type ; Photometry ; Effective temperatures Keywords: binaries: close - binaries: general - stars: activity - stars: late-type - stars: rotation - starspots - techniques: photometric Abstract: We have searched the Kepler light curves of ∼3900 M-star targets for evidence of periodicities that indicate, by means of the effects of starspots, rapid stellar rotation. Several analysis techniques, including Fourier transforms, inspection of folded light curves, "sonograms", and phase tracking of individual modulation cycles, were applied in order to distinguish the periodicities due to rapid rotation from those due to stellar pulsations, eclipsing binaries, or transiting planets. We find 178 Kepler M-star targets with rotation periods, Prot<2 days, and 110 with Prot<1 day. Some 30 of the 178 systems exhibit two or more independent short periods within the same Kepler photometric aperture, while several have 3 or more short periods. Adaptive optics imaging and modeling of the Kepler pixel response function for a subset of our sample support the conclusion that the targets with multiple periods are highly likely to be relatively young physical binary, triple, and even quadruple M star systems. We explore in detail the one object with four incommensurate periods all less than 1.2 days, and show that two of the periods arise from one of a close pair of stars, while the other two arise from the second star, which itself is probably a visual binary. If most of these M-star systems with multiple periods turn out to be bound M-stars, this could prove a valuable way discovering young hierarchical M-star systems; the same approach may also be applicable to G and K stars. The ∼5% occurrence rate of rapid rotation among the ∼3900 M star targets is consistent with spin evolution models that include an initial contraction phase followed by magnetic braking, wherein a typical M star can spend several hundred Myr before spinning down to periods longer than 2 days. Description: In all, we find 297 of the 3897 targets exhibit the requisite significant Fourier transform (FT) signal comprising a base frequency plus its harmonic, with the base frequency exceeding 0.5 cycles/day (i.e., Prot<2 days). We believe that the majority of these periodicities are likely to be due to stellar rotation manifested via starspots, but a significant number may be due to planet transits and binary eclipses. The individual FTs for these systems were further examined to eliminate those which were clearly not due to rotating starspots. In all cases we folded the data modulo the detected fundamental period, and were readily able to rule out cases due to transiting planets since their well-known sharp, relatively rectangular dipping profiles are characteristic. Of course, we also checked the KOI list for matches. Any of the objects that appear in the Kepler eclipsing binary ("EB") star catalog (e.g., Matijevic et al. 2012AJ....143..123M) were likewise eliminated. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 15 178 Kepler M Stars Exhibiting a Short Rotation Period table2.dat 108 37 Kepler M Stars Exhibiting Two or More Short Rotation Periods
See also: V/133 : Kepler Input Catalog (Kepler Mission Team, 2009) J/A+A/557/L10 : Rotation periods of 12000 Kepler stars (Nielsen+, 2013) J/A+A/560/A4 : Rotation periods of active Kepler stars (Reinhold+, 2013) J/MNRAS/432/1203 : Rotation periods of M-dwarf stars (McQuillan+, 2013) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 8 I8 --- KIC "Kepldr(Input Catalog number (Cat. V/133) 10- 15 F6.4 d Per Rotation period (1)
Note (1): 178 Kepler targets exhibiting at least one starspot rotation period shorter than 2 days. If more than one period is present, only the shortest period is listed here. For systems with more than one short rotation period see Table 2.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 8 I8 --- KIC Kepler Input Catalog number (Cat. V/133) 10- 11 I2 h RAh Hour of Right Ascension (J2000) 13- 14 I2 min RAm Minute of Right Ascension (J2000) 16- 20 F5.2 s RAs Second of Right Ascension (J2000) 22- 23 I2 deg DEd Degree of Declination (J2000) 25- 26 I2 arcmin DEm Arcminute of Declination (J2000) 28- 32 F5.2 arcsec DEs Arcsecond of Declination (J2000) 34- 37 F4.1 mag Kpmag Kepler magnitude 39- 42 I4 deg Teff Composite effective temperature 44- 49 F6.4 d PerA Source A rotation period (1) 50 A1 --- n_PerA [ab] Note on PerA (2) 52- 57 F6.4 d PerB Source B rotation period (1) 58 A1 --- n_PerB [b] Note on PerB (2) 60- 66 F7.4 d PerC ? Source C rotation period (1) 67 A1 --- n_PerC [c] Note on PerC (2) 69- 75 F7.4 d PerD ? Source D rotation period (1) 77-107 A31 --- Com Comment on the stellar neighbors (3) 108 A1 --- n_Com [d] Note on Com (4)
Note (1): Two of the periods (A, B) arise from one of a close pair of stars, while the other two arise (C, D) from the second star, which itself is probably a visual binary. Note (2): Note as follows: a = Inferred from only the base frequency and no higher harmonics; b = Sufficiently close that these may result from differential rotation of a single star; c = The period of an eccentric binary component of the system. Note (3): Inferred from the UKIRT J-band images, as well as the Keck AO images - where available; angular distances to some of the neighboring stars are noted. Note (4): Note as follows: d = The other stars are of a distinctly different, i.e., hotter, spectral type.
History: From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 12-Jul-2017
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