J/AJ/155/23 Low-mass fast rotators in the solar neighborhood (Saylor+, 2018)
Light-curve modulation of low-mass stars in K2.
I. Identification of 481 fast rotators in the solar neighborhood.
Saylor D., Lepine S., Crossfield I., Petigura E.A.
<Astron. J., 155, 23 (2018)>
=2018AJ....155...23S 2018AJ....155...23S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Stars, population II ; Proper motions ;
Photometry, ultraviolet ; Photometry, UBV ; Photometry, infrared
Keywords: stars: activity - stars: low-mass - stars: Population II -
stars: rotation - surveys
Abstract:
The K2 mission is targeting large numbers of nearby (d<100 pc) GKM dwarfs
selected from the SUPERBLINK proper motion survey (µ>40 mas/yr, V<20).
Additionally, the mission is targeting low-mass, high proper motion
stars associated with the local (d<500 pc) Galactic halo population
also selected from SUPERBLINK. K2 campaigns 0 through 8 monitored a
total of 26518 of these cool main-sequence stars. We used the
auto-correlation function to search for fast rotators by identifying
short-period photometric modulations in the K2 light curves. We
identified 481 candidate fast rotators with rotation periods <4 days
that show light-curve modulations consistent with starspots. Their
kinematics show low average transverse velocities, suggesting that
they are part of the young disk population. A subset (13) of the fast
rotators is found among those targets with colors and kinematics
consistent with the local Galactic halo population and may represent
stars spun up by tidal interactions in close binary systems. We
further demonstrate that the M dwarf fast rotators selected from the
K2 light curves are significantly more likely to have UV excess and
discuss the potential of the K2 mission to identify new nearby young
GKM dwarfs on the basis of their fast rotation rates. Finally, we
discuss the possible use of local halo stars as fiducial, non-variable
sources in the Kepler fields.
Description:
The current version of the SUPERBLINK proper motion catalog lists stars
with proper motions µ>40 mas/yr and visual magnitudes V<20 over the
entire sky north of decl.=-30°; this area includes all fields observable
in K2 (Lepine 2005, J/AJ/130/1247; Lepine & Gaidos 2011, J/AJ/142/138).
We have cross-matched the SUPERBLINK catalog with the final target lists
for K2 campaigns 0-8. We used a search radius of 5 arcsec to find matches
that identified 26518 high proper motion SUPERBLINK stars monitored by
Kepler in the initial K2 campaigns.
Fast rotators are identified from our combined auto-correlation function
(ACF) and Fast Fourier Transform (FFT) analysis, with the FFT identifying
regular peaks in the ACF corresponding to a recurrent signal and its
aliases, and with individual fits to these peaks used to compute the
associated stellar rotation period and assess the quality of the
identification. This combined ACF and FFT algorithm identified 481
candidate fast rotators in the SUPERBLINK stars monitored in K2
campaigns 0-8.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 109 481 Low-mass Fast Rotators in K2 Campaigns 0-8
table6.dat 109 9999 SUPERBLINK Stars Observed in K2 Campaigns 0-8
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See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
J/AJ/130/1247 : High proper motion stars in the DSS. III (Lepine+, 2005)
J/AJ/142/138 : All-sky catalog of bright M dwarfs (Lepine+, 2011)
J/ApJ/775/L11 : Stellar rotation periods for KOIs (McQuillan+, 2013)
J/ApJS/224/2 : K2 EPIC stellar properties for 138600 targets (Huber+, 2016)
Byte-by-byte Description of file: table2.dat table6.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- SB Source name (PM IHHMMm+DDMMWw)
18- 26 I9 --- EPIC Name in Ecliptic Plane Input Catalog
(Huber et al. 2016, J/ApJS/224/2)
28- 37 F10.6 deg RAdeg Right Ascension in decimal degrees (ICRS)
39- 48 F10.6 deg DEdeg Declination in decimal degrees (ICRS)
50- 55 F6.3 arcsec/yr pmRA [-0.443/1.221] Proper motion in Right
Ascension (pmRA*cosDE)
57- 62 F6.3 arcsec/yr pmDE [-2.669/0.298] Proper motion in Declination
64- 68 F5.2 mag NUV [12.22/24.61]?=99.99 GALEX near-UV magnitude
70- 74 F5.2 mag Vmag [5.61/21.1] Kepler V magnitude
76- 80 F5.2 mag V-J [-1.76/6.77]?=99.9 Color using 2MASS infrared
J magnitude
82- 85 F4.2 d Prot [0.12/3.99]? Calculated photometric rotation
period (not in Table 6)
87- 91 F5.3 d e_Prot [0/1.433]? Uncertainty in Prot (not in
Table 6)
93- 96 F4.2 --- A [0.03/2.58]? Amplitude of the auto-correlation
function (ACF) peak (not in Table 6) (1)
98-101 F4.1 --- B [2/16.9]? Spacing of aliases in the ACF
(not in Table 6) (2)
103-107 F5.3 --- sigma [0/0.552]? Amplitude of the rotation
modulation (not in Table 6) (3)
109 I1 --- NK2 [0/8] K2 campaign number
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Note (1): Average correlation value for the first five maxima in the
auto-correlation function.
Note (2): Parameter indicating the dominance of the auto-correlation peak
(see the text).
Note (3): Standard deviation in the light curve after detrending, showing the
amplitude of the variability signal.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 13-Sep-2018