J/AJ/152/113 Pleiades members with K2 light curves. I. Periods (Rebull+, 2016)
Rotation in the Pleiades with K2. I. Data and first results.
Rebull L.M., Stauffer J.R., Bouvier J., Cody A.M., Hillenbrand L.A.,
Soderblom D.R., Valenti J., Barrado D., Bouy H., Ciardi D.,
Pinsonneault M., Stassun K., Micela G., Aigrain S., Vrba F., Somers G.,
Christiansen J., Gillen E., Collier Cameron A.
<Astron. J., 152, 113-113 (2016)>
=2016AJ....152..113R 2016AJ....152..113R (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Rotational velocities ; Cross identifications
Keywords: globular clusters: individual: Pleiades - stars: rotation
Abstract:
Young (125Myr), populous (>1000 members), and relatively nearby, the
Pleiades has provided an anchor for stellar angular momentum models
for both younger and older stars. We used K2 to explore the
distribution of rotation periods in the Pleiades. With more than 500
new periods for Pleiades members, we are vastly expanding the number
of Pleiades with periods, particularly at the low-mass end. About 92%
of the members in our sample have at least one measured spot-modulated
rotation period. For the ∼8% of the members without periods,
non-astrophysical effects often dominate (saturation, etc.), such that
periodic signals might have been detectable, all other things being
equal. We now have an unusually complete view of the rotation
distribution in the Pleiades. The relationship between P and
(V-Ks)0 follows the overall trends found in other Pleiades
studies. There is a slowly rotating sequence for 1.1≲(V-Ks)0≲3.7
and a primarily rapidly rotating population for (V-Ks)0≳5.0.
There is a region in which there seems to be a disorganized
relationship between P and (V-Ks)0 for 3.7≲(V-Ks)0≲5.0.
Paper II continues the discussion, focusing on multiperiod structures,
and Paper III speculates about the origin and evolution of the period
distribution in the Pleiades.
Description:
Members of the Pleiades were observed in K2 Campaign 4. The NASA K2
mission (Howell et al. 2014PASP..126..398H 2014PASP..126..398H), using the repurposed 1m
Kepler spacecraft, observed the Pleiades cluster nearly continuously
for 72 days. All of the stars shown were observed in the long-cadence
(∼30-minute exposure) mode. Thirty-four of these stars were
additionally observed in fast cadence (∼1-minute exposure), but those
data are beyond the scope of the present work. There are 1020 unique
K2 long-cadence light curves (see Table7).
Kepler pixel sizes are relatively large, 3.98''*3.98'', and the 95%
encircled energy diameter ranges from 3.1 to 7.5 pixels with a median
value of 4.2 pixels. During the K2 portion of the mission, because
only two reaction wheels can be used, the whole spacecraft slowly
drifts and then repositions regularly every 0.245 days.
We find periods for 798 out of our sample of 1020 K2 light curves of
candidate Pleiads. However, not all of those stars may be members.
Our final list of members is in Table2 (for the periodic members).
Basic parameters for stars not detected as periodic are listed in
Table3. Five of these stars have reported periods in the literature
that we do not recover. For some objects, we found a period during our
analysis, but individual inspection of the light curves suggests that
whatever is causing the repeating pattern is not a spot-modulated
rotation period. For a complete list of these objects, see Table4. In
Table5, we list the objects that are too bright or too faint for our
sample. There are more than 150 stars where a K2 light curve was
obtained, presumably because some literature considered these objects
as Pleiades members. However, consideration of each of the individual
stars, suggests that these are not, in fact, likely to be Pleiades
members. They are listed in Table6 with the period(s) we derived. The
Table7 gives some of the common synonyms for our targets in the
literature.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 145 759 Periods and supporting data for periodic
Pleiades members
table3.dat 95 67 Supporting data for Pleiades members not
detected to be periodic in the K2 data
table4.dat 145 28 Timescales
table5.dat 92 41 Targets that are too bright or too faint
table6.dat 102 153 Targets taken as non-members
table7.dat 230 1020 Contents of online cross-identifications list
--------------------------------------------------------------------------------
See also:
II/281 : 2MASS 6X Point Source Working Database / Catalog (Cutri+ 2006)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/258 : Pleiades positions and proper motions (Wang+, 1996)
II/131 : Tonantzintla Pleiades Flare Stars (Haro+ 1982)
J/AJ/152/114 : Pleiades members with K2 LCs. II. (Rebull+, 2016)
J/AJ/152/115 : Pleiades members with K2 LCs. III. (Stauffer+, 2016)
J/ApJS/224/2 : K2 EPIC properties for 138600 targets (Huber+, 2016)
J/A+A/579/A19 : K2 Variable Catalogue (Armstrong+, 2015)
J/A+A/577/A148 : The Seven Sisters DANCe. I. Pleiades (Bouy+, 2015)
J/AJ/148/30 : BVI photometry of 350 Pleiades stars (Kamai+, 2014)
J/MNRAS/422/1495 : UKIDSS Galactic Clusters Survey Pleiades members
(Lodieu+ 2012)
J/MNRAS/408/475 : HATNet Pleiades Rotation Period Catalogue (Hartman+, 2010)
J/A+A/416/125 : RI photometry in alpha Per and Pleiades (Deacon+, 2004)
J/MNRAS/313/347 : Pleiades low-mass stars and brown dwarfs (Pinfield+, 2000)
J/A+A/335/183 : Pleiades low-mass stars rotational vel. (Queloz+ 1998)
J/A+A/332/575 : Pleiades member list (Belikov+ 1998)
J/A+A/329/101 : Masses of Pleiades members (Raboud+ 1998)
J/A+A/323/139 : K magnitude of Pleiades low-mass binaries (Bouvier+ 1997)
J/A+A/299/696 : Pleiades field Membership probabilities (Schilbach+, 1995)
J/other/PZ/23.141 : Flare stars in the Pleiades (Kazarovets 1993)
J/ApJS/85/315 : F, G and K dwarf stars of the Pleiades (Soderblom+ 1993)
J/A+AS/100/607 : Very low mass proper motion members in Pleiades
(Hambly+ 1993)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Number in the Ecliptic Plane Input Catalog (EPIC)
for K2 (1)
11- 28 A18 --- Name Position-based name (HHMMSS.ss+DDMMSS.s; J2000)
30- 37 F8.5 deg RAdeg Right Ascension in decimal degrees (J2000)
39- 46 F8.5 deg DEdeg Declination in decimal degrees (J2000)
48- 70 A23 --- OName Other identifier
72- 76 F5.2 mag Vmag [6.7/20.8]? The V-band magnitude (in Vega mag),
if observed (G1)
78- 82 F5.2 mag Ksmag [6.2/14.5] The 2MASS Ks (K-short) band magnitude
(in Vega mag), if observed (G1)
84- 88 F5.2 mag (V-K)0 [-0.2/7.2] Dereddened V-Ks, (V-Ks)0, color
index (directly observed, if V and Ks exist,
or inferred) (vmk0) (G1)
90- 96 F7.4 d Prot [0.035/22.2] Primary period, taken to be rotation
period (P1) (2)
98-103 F6.4 d Per2 [0.03/9.7]? Secondary period (P2) (3)
105-110 F6.4 d Per3 [0.036/6]? Tertiary period (P3) (3)
112-118 F7.4 d Per4 [0.03/11]? Quaternary period (P4) (3)
120-124 F5.3 mag Amp [0.001/0.6] Amplitude of the 10th to 90th
percentile (ampl) (4)
126-127 A2 --- --- [LC]
128 I1 --- LC Light curve used as "best" (1, 2, 3, or 4) (5)
130-133 A4 --- Mm Pleiades membership indicator (best or ok) (G2)
135-139 F5.2 d LPer [0.1/11.3]? Literature (rotation) period, if
available (Plit) (6)
141-145 F5.1 km/s vsini [2.4/140]? Literature rotational velocity, if
available (refer to Section 2.3.2 in the paper
for details)
--------------------------------------------------------------------------------
Note (1): Our set of members consists of 799 high-confidence ("best") Pleiades
members and 54 more lower-confidence ("ok") members, for a total of 853. Thus,
we find that 167 of the candidate Pleiads with K2 light curves are unlikely to
be members. Omitting the too bright and too faint stars for our sample, there
are 775 high-confidence members, with 51 more lower-confidence members (for a
total of 826 members). Out of those 775 (best members), 716 (92.4%) have at
least one measured period that we believe in the overwhelming majority of
cases to be a rotation period and due to starspots. Including the
lower-confidence members, 759/826 (91.9%) have at least one measured period
that we believe to be the rotation period.
Note (2): We looked for periodic signals using primarily the NASA Exoplanet
Archive Periodogram Service:
http://exoplanetarchive.ipac.caltech.edu/cgi-bin/Periodogram/nph-simpleupload
(Akeson et al. 2013PASP..125..989A 2013PASP..125..989A). We also looked for periods using CLEAN
(Roberts et al. 1987AJ.....93..968R 1987AJ.....93..968R). See Section 2.2 in the paper for details
about the periods finding.
Note (3): See Paper II (Rebull et al. 2016, Cat. J/AJ/152/114) for multiperiodic
stars.
Note (4): We calculated the amplitude of the light curves in magnitudes by
assembling the distribution of all points in the light curve, taking the log
of the 90th percentile flux, subtracting from that the log of the 10th
percentile flux, and multiplying by 2.5. See Section 3.3 in the paper for more
details.
Note (5): We have used different sets of LCs employing the following reductions:
1 = The Pre-search Data Conditioning (PDC) version generated by the Kepler
project and obtained from MAST, the Mikulski Archive for Space Telescopes;
2 = A version with moving apertures obtained following A. M. Cody et al.
(2016, in preparation);
3 = A version using a semiparametric Gaussian process model used by
Aigrain et al. (2015MNRAS.447.2880A 2015MNRAS.447.2880A, 2016MNRAS.459.2408A 2016MNRAS.459.2408A);
4 = The "self-flat-fielding" approach used by Vanderburg & Johnson
(2014PASP..126..948V 2014PASP..126..948V) from MAST.
Note (6): In order to verify our period-finding approach, it is useful to
compare to prior Pleiades results. There are two recent papers that obtain
periods in the Pleiades from large-field photometric monitoring. Hartman et
al. 2010 (Cat. J/MNRAS/408/475) used HATNet and reported periods for 383
Pleiads. Covey et al. 2016ApJ...822...81C 2016ApJ...822...81C used Palomar Transient Facility
(PTF) and report periods for 138 Pleiads. Please refer to Section 2.3.1 in the
paper for more details about the literature periods.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Number in the Ecliptic Plane Input Catalog (EPIC)
for K2
11 A1 --- f_EPIC [a] Flag if not recovered literature period (1)
13- 30 A18 --- Name Position based name (HHMMSS.ss+DDMMSS.s; J2000)
32- 39 F8.5 deg RAdeg Right Ascension in decimal degrees (J2000)
41- 48 F8.5 deg DEdeg Declination in decimal degrees (J2000)
50- 72 A23 --- OName Other identifier
74- 78 F5.2 mag Vmag [6.8/20.8]? The V-band magnitude (in Vega mag), if
observed (G1)
80- 84 F5.2 mag Ksmag [6.4/14.5] The 2MASS Ks (K-short) band magnitude
(in Vega mag), if observed (G1)
86- 90 F5.2 mag (V-K)0 [-0.2/9.3] Dereddened V-Ks, (V-Ks)0, color
index (directly observed, if V and Ks exist, or
inferred) (G1)
92- 95 A4 --- Mm Pleiades membership indicator (best or ok) (G2)
--------------------------------------------------------------------------------
Note (1): Three stars have periods in the literature that we do not recover from
the K2 data:
EPIC211060530 = 0.622 days;
EPIC211078009 = 3.158 days;
EPIC211094556 = 0.17 days.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Number in the Ecliptic Plane Input Catalog (EPIC)
for K2 (1)
11- 28 A18 --- Name Position based name (HHMMSS.ss+DDMMSS.s; J2000)
30- 37 F8.5 deg RAdeg Right Ascension in decimal degrees (J2000)
39- 46 F8.5 deg DEdeg Declination in decimal degrees (J2000)
48- 70 A23 --- OName Other identifier
72 A1 --- f_tau1 [~] Approximate flag on tau1
73- 78 F6.3 d tau1 [5.2/35]? Repeating pattern timescale
80- 81 I2 d tau2 [30]? Upper value when timescale range
83- 93 A11 --- n_tau2 Note about the timescale
95- 98 A4 --- Mm Pleiades membership indicator (best, ok,
or NM=non-member) (G2)
100-145 A46 --- Note Additional comments
--------------------------------------------------------------------------------
Note (1): For these objects, we found a period during our analysis, but
individual inspection of the light curves suggests that whatever is causing
the repeating pattern is not a spot-modulated rotation period. We have
opted to describe the period suggested by the repeating pattern as
"timescale" rather than a period.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Number in the Ecliptic Plane Input Catalog (EPIC)
for K2 (1)
11- 28 A18 --- Name Position based name (HHMMSS.ss+DDMMSS.s; J2000)
30- 37 F8.5 deg RAdeg Right Ascension in decimal degrees (J2000)
39- 46 F8.5 deg DEdeg Declination in decimal degrees (J2000)
48- 69 A22 --- OName Other identifier
71- 78 F8.6 d Per1 [0.23/0.68]? Period, if detected
80- 87 F8.6 d Per2 [0.24/0.65]? Second period, if detected
89- 92 A4 --- Mm Pleiades membership indicator (best, ok,
or NM=non-member) (G2)
--------------------------------------------------------------------------------
Note (1): We empirically determined that our brightness and faintness limits are
effectively Ks≲6 and Ks≳14.5, respectively. Sometimes, despite these
limits, we were still able to derive a period (and in two cases, two
distinct periods).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Number in the Ecliptic Plane Input Catalog (EPIC)
for K2 (1)
11- 28 A18 --- Name Position based name (HHMMSS.ss+DDMMSS.s; J2000)
30- 37 F8.5 deg RAdeg Right Ascension in decimal degrees (J2000)
39- 46 F8.5 deg DEdeg Declination in decimal degrees (J2000)
48- 70 A23 --- OName Other identifier
72- 76 F5.2 mag Vmag [10.45/20.41]? The V band magnitude (in Vega mag),
if observed (G1)
78- 82 F5.2 mag Ksmag [7.28/14.48] The 2MASS Ks (K-short) band magnitude
(in Vega mag), if observed (G1)
84- 87 F4.2 mag (V-K)0 [1.3/7] Dereddened V-Ks, (V-Ks)0, color
index (directly observed, if V and Ks exist, or
inferred) (G1)
89- 94 F6.3 d Per1 [0.24/29.6]? Primary period we derived
98-102 F5.3 d Per2 [0.24/5.1]? Other period or timescale
--------------------------------------------------------------------------------
Note (1): There are more than 150 stars where a K2 light curve was obtained,
presumably because some literature considered these objects as Pleiades
members. However, consideration of each of the individual stars, including
the references mentioned in Section 2.5 in the paper, suggests that these
are not, in fact, likely to be Pleiades members.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC Number in the Ecliptic Plane Input Catalog (EPIC)
for K2
11- 33 A23 --- Name More common name used in the literature
35- 37 A3 --- --- [HII]
38- 43 A6 --- HII Identifier in HII catalog (Hertzsprung
1947AnLei..19A...1H 1947AnLei..19A...1H)
45- 47 A3 --- --- [HCG]
48- 50 I3 --- HCG [5/516]? Identification number in HCG catalog
(Haro, Chavira, and Gonzalez 1982, Cat. II/131;
Kazarovets 1993, Cat. J/other/PZ/23.141)
51 A1 --- f_HCG [b] Flag "b" on HCG377
53- 55 A3 --- --- [HHJ]
56- 58 I3 --- HHJ [5/440]? Identification number in HHJ catalog
(Hambly, Hawkins, and Jameson 1993,
Cat. J/A+AS/100/607)
60- 63 A4 --- --- [PELS]
64- 66 I3 --- PELS [3/192]? Identification number in Pels catalog (van
Leeuwen et al. 1986A&AS...65..309V 1986A&AS...65..309V)
68- 69 A2 --- --- [DH]
70- 72 I3 --- DH [10/916]? Sequence number in DH catalog (Deacon &
Hambly 2004, Cat. J/A+A/416/125)
74- 76 A3 --- --- [SRS]
77- 81 I5 --- SRS [12896/92992]? Identification number in SRS catalog
(Schilbach, Robichon, Souchay, and Guibert 1995,
Cat. J/A+A/299/696; Belikov et al. 1998,
Cat. J/A+A/332/575)
83- 91 F9.7 --- --- [0.02/0.99]?
93- 99 A7 --- BPL Identifier in BPL catalog (Pinfield et al. 2000,
Cat. J/MNRAS/313/347)
101-107 A7 --- n_BPL Possible other BPL identification number
109-110 A2 --- --- [SK]
111-113 I3 --- SK [13/778]? Identification number in SK catalog
(Stauffer, Klemola et al. 1991AJ....101..980S 1991AJ....101..980S)
115-116 A2 --- --- [Tr]
117-121 A5 --- Tr Identifier in Trumpler 1921PASP...33..214T 1921PASP...33..214T
123-135 A13 --- n_Tr Possible other Tr identifier
137-139 A3 --- --- [WCZ]
140-142 I3 --- WCZ [4/476]? Identification number in WCZ catalog
(Wang, Chen, Zhao, and Jiang 1996, Cat. I/258)
144-169 A26 --- SIMBAD Name used in Simbad as primary identifier
171-188 A18 --- Lodieu Position-based identifier from catalog of Lodieu et
al. 2012 (Cat. J/MNRAS/422/1495)
(HHMMSS.ss+DDMMSS.s, J2000)
190-208 A19 --- DANCe DANCe survey identifier from Bouy et al. 2015
(Cat. J/A+A/577/A148) (JHHMMSS.ss+DDMMSS.s)
210-225 A16 --- 2MASS Identifier in 2MASS All-sky point source catalog
(Cat. II/246) (HHMMSSss+DDMMSSs, J2000)
227-230 A4 --- f_2MASS [tm6x] Flag on 2MASS (tm6x=6x 2MASS data,
Cat. II/281)
--------------------------------------------------------------------------------
Global Notes:
Note (G1): Ideally, we would have Teff or mass for all of our targets.
However, those quantities can be very model dependent. Because we preferred
to keep our discussion of the new K2 rotation period data on an empirical
basis to the extent possible, our goal was to use an observed color as the
proxy for mass or Teff. The broadband color that acts as the best such
proxy over the entire mass range for which we have periods is (V-Ks)0.
While Ks is widely available from 2MASS, V is harder to find. We only
have measured V-band photometry for about half of the periodic stars; it
was necessary to estimate V magnitudes from other photometry for the rest.
The highest-quality V-band photometry we have is from phototube photometry
reported in Johnson & Mitchell 1958ApJ...128...31J 1958ApJ...128...31J, Landolt
1979ApJ...231..468L 1979ApJ...231..468L, Stauffer & Hartmann 1987ApJ...318..337S 1987ApJ...318..337S, or references
therein, or CCD photometry from Kamai et al. 2014 (Cat. J/AJ/148/30).
Additional V-band photometry, generally for fainter members, was obtained
using CCD cameras on small telescopes by Prosser et al. 1991AJ....101.1361P 1991AJ....101.1361P
and Stauffer et al. 1998ApJ...504..805S 1998ApJ...504..805S. For the remaining stars (mostly
faint M dwarfs), we have adopted measured photometry at bands near in
wavelength to V. Please see Section 2.4 in the paper for additional details
about the photometry.
Note (G2): We evaluated each object using a combination of proper motions and
photometric position in an optical color-magnitude diagram (CMD). As a
result of this analysis, we have the three following sets of members:
best = Highest confidence (our determination) Pleiades member;
ok = Lower confidence (our determination) Pleiades member, where the
evidence for membership is suggestive but not conclusive;
NM = Non-member.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
15-Nov-2017: Insert into VizieR
23-Jul-2018: One name corrected in column Name of Table 7.
References:
Rebull et al., Paper II 2016AJ....152..114R 2016AJ....152..114R, Cat. J/AJ/152/114
Stauffer et al., Paper III 2016AJ....152..115S 2016AJ....152..115S, Cat. J/AJ/152/115
Rebull et al., Paper IV 2017ApJ...839...92R 2017ApJ...839...92R, Cat. J/ApJ/839/92
Rebull et al., Paper V 2018AJ....155..196R 2018AJ....155..196R
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 12-Dec-2016