J/ApJ/809/161 X-ray obs. and membership probabilities of M37 (Nunez+, 2015)
Linking stellar coronal activity and rotation at 500 Myr:
a deep Chandra observation of M37.
Nunez A., Agueros M.A., Covey K.R., Hartman J.D., Kraus A.L., Bowsher E.C.,
Douglas S.T., Lopez-Morales M., Pooley D.A., Posselt B., Saar S.H.,
West A.A.
<Astrophys. J., 809, 161 (2015)>
=2015ApJ...809..161N 2015ApJ...809..161N (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources ; Photometry, ugriz ; Cross identifications ;
Clusters, open ; Stars, masses
Keywords: open clusters and associations: individual: M37;
stars: activity; stars: coronae; stars: rotation;
X-rays: individual: M37
Abstract:
Empirical calibrations of the stellar age-rotation-activity relation
(ARAR) rely on observations of the co-eval populations of stars in
open clusters. We used the Chandra X-ray Observatory to study M37, a
500-Myr-old open cluster that has been extensively surveyed for
rotation periods (Prot). M37 was observed almost continuously for
five days, for a total of 440.5ks, to measure stellar X-ray
luminosities (LX), a proxy for coronal activity, across a wide range
of masses. The cluster's membership catalog was revisited to calculate
updated membership probabilities from photometric data and each star's
distance to the cluster center. The result is a comprehensive sample
of 1699 M37 members: 426 with Prot, 278 with X-ray detections, and
76 with both. We calculate Rossby numbers, R0=Prot/τ, where
τ is the convective turnover time, and ratios of the
X-ray-to-bolometric luminosity, LX/Lbol, to minimize mass
dependencies in our characterization of the rotation-coronal activity
relation at 500Myr. We find that fast rotators, for which
R0<0.09±0.01, show saturated levels of activity, with
log(LX/Lbol)=-3.06±0.04. For R0≥0.09±0.01, activity is
unsaturated and follows a power law of the form R0β, where
β=-2.03+0.17-1.14. This is the largest sample available for
analyzing the dependence of coronal emission on rotation for a
single-aged population, covering stellar masses in the range
0.4-1.3M☉, Prot in the range 0.4-12.8 days, and LX in the
range 1028.4-30.5erg/s. Our results make M37 a new benchmark open
cluster for calibrating the ARAR at ages of ∼500Myr.
Description:
The central field of M37 was observed five separate times between 2011
November 14 20:58 and 2011 November 19 15:31 UTC for a total of
440.5ks with the Advanced CCD Imaging Spectrometer (ACIS; obsID 13655,
13656, 13657, 14366 and 14367).
ME08 (Messina+, 2008, J/A+A/483/253) selected images from the survey
taken with the 1.0m telescope at the Mt. Lemmon Optical Astronomy
Observatory, AZ, of a 22.2"x22.2" area centered on M37, and used both
the Scargle-Press and CLEAN periodogram techniques to measure
variability for stars with 13<V<20mag. ME08 found 135 variables and
reported for 120 of them.
HA08 (Hartman+, 2008, J/ApJ/675/1233) used filters on Megacam and the
6.5m MMT telescope at the MMT Observatory, AZ, to survey a 24' area
around the center of M37. Finally, HA09 (Hartman+, 2009,
J/ApJ/691/342) identified periodic variability due to rotation for 575
variable stars.
We consolidated photometry and Prot from the surveys described above
(ME08 and HA08).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 258 774 Chandra catalog: basic source properties
table5.dat 205 3766 Catalog of optical objects: basic properties
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See also:
J/AJ/145/143 : XMM observations of α Per (Pillitteri+, 2013)
J/MNRAS/426/3403 : UKIDSS-GCS α Per members (Lodieu+, 2012)
J/ApJ/743/48 : Stellar rotation periods & X-ray luminosities (Wright+, 2011)
J/ApJS/195/10 : The CDF-S survey: 4Ms source catalogs (Xue+, 2011)
J/ApJ/733/L9 : Stellar rotation for 71 NGC 6811 members (Meibom+, 2011)
J/MNRAS/400/299 : Chandra deep protocluster survey (Lehmer+, 2009)
J/ApJ/691/342 : griBVI photometry in M37 (Hartman+, 2009)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/A+A/490/113 : X-ray sources in NGC 752 (Giardino+, 2008)
J/AJ/136/118 : Open clusters as galactic disk tracers. I. (Frinchaboy+, 2008)
J/A+A/485/303 : Radial velocities for 1309 stars & 166 OCl (Mermilliod+, 2008)
J/A+A/483/253 : BV photometry of NGC 2099 variables (Messina+, 2008)
J/ApJ/675/1254 : M37 variable stars (Hartman+, 2008)
J/ApJ/675/1233 : gri photometry in M37 (NGC 2099) (Hartman+, 2008)
J/AJ/134/2340 : Praesepe & Coma Berenices clusters' membership (Kraus+, 2007)
J/MNRAS/380/712 : ZYJHK photometry in Pleiades (Lodieu+, 2007)
J/ApJS/169/401 : ChaMP X-ray point source catalog (Kim+, 2007)
J/AJ/130/873 : Properties of BQS objects in the SDSS DR3 area (Jester+, 2005)
J/MNRAS/342/1241 : Low-mass stars in M45 and M44 (Pinfield+, 2003)
J/A+A/397/147 : Activity-rotation relationship in stars (Pizzolato+ 2003)
J/A+A/388/168 : Absolute proper motions of 93 open clusters (Dias+, 2002)
J/A+A/381/65 : BVI photometry of NGC 2099 (Nilakshi+, 2002)
J/A+A/341/751 : ROSAT HRI observations of the Pleiades (Micela+ 1999)
J/AN/319/215 : Alpha Per cluster low-mass members. II. (Prosser+, 1998)
J/A+A/335/183 : Pleiades low-mass stars rotational velocities (Queloz+ 1998)
J/A+A/331/81 : Hyades membership (Perryman+ 1998)
J/ApJS/102/75 : ROSAT Observations of the Pleiades (Micela+ 1996)
J/ApJ/448/683 : Hyades RASS observations (Stern+ 1995)
J/ApJ/348/557 : X-ray studies of stars in the Pleiades (Micela+, 1990)
J/ApJ/315/687 : X-Ray emission from solar-type stars: F and G (Maggio+, 1987)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [1/1018] X-ray catalog XID sequence number
6- 23 A18 --- CXOU IAU designation (HHMMSS.ss+DDMMSS.s; J2000)
25- 33 F9.6 deg RAdeg Right ascension of X-ray source (J2000)
35- 43 F9.6 deg DEdeg Declination of X-ray source (J2000)
45- 56 F12.9 arcsec e_Pos [0.1/19] 80% confidence level X-ray positional
uncertainty
58- 61 F4.1 arcmin theta [0.3/18] Off-axis angle of X-ray source
63- 68 F6.1 ct Fcts [2/5020] Net source counts in the 0.5-7keV
band (ct-f)
70- 74 F5.2 ct E_Fcts 1-sigma upper bound of ct-f
76- 81 F6.3 ct e_Fcts 1-sigma lower bound of ct-f
83- 88 F6.1 ct Scts [-2/3171] Net source counts in the 0.5-2keV
band (ct-s)
90- 94 F5.2 ct E_Scts 1-sigma upper bound of ct-s
96-101 F6.3 ct e_Scts ? 1-sigma lower bound of ct-s
103-108 F6.1 ct Hcts [-8/1899] Net source counts in the 2-7keV
band (ct-h)
110-114 F5.2 ct E_Hcts 1-sigma upper bound of ct-h
116-122 F7.4 ct e_Hcts ? 1-sigma lower bound of ct-h
124-131 E8.2 mW/m2 F0.5-7 Absorbed energy flux in the 0.5-7 keV band
133-140 E8.2 mW/m2 F0.5-2 ? Absorbed energy flux in the 0.5-2 keV band
142-149 E8.2 mW/m2 F2-7 ? Absorbed energy flux in the 2-7 keV band
151-154 F4.2 keV Emed [0.7/6.4] Median photon energy in
the 0.5-7keV band
156-159 F4.2 --- PSFf Fraction of the PSF enclosed within
extraction region
161-171 E11.5 10-7W LX ? X-ray luminosity in the 0.1-2.4 keV band
173-183 E11.5 10-7W e_LX ? standard deviation of LX
185-195 E11.5 [-] logP [0/0.005] Logarithmic probability P that
extracted X-ray counts are solely from
background
197-208 F12.9 --- SNR [0.7/63.3] ct-f divided by E_ct-f
210-211 A2 --- A Source anomalies (1)
213-213 A1 --- Var Variability based on K-S statistic (2)
215-220 A6 --- OID ? ID of optical match from Hartman+, 2008,
J/ApJ/675/1233
222-232 F11.8 deg RAOdeg ? Right Ascension of optical match (J2000)
234-244 F11.8 deg DEOdeg ? Declination of optical match (J2000)
246-256 F11.9 arcsec X-O [0.02/7.3]? Offset between X-ray source
and optical match
258 A1 --- Note ? Additional notes (3)
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Note (1): Source anomalies as follows:
f = fractional time that source was on a detector is <0.9
a = photometry and spectrum may contain >10% afterglow events
Note (2): K-S statistic ranges as follows:
a = PKS<0.05
b = 0.005<PKS<0.05
c = PKS<0.005
Note (3): Note as follows:
g = In ACIS-S3 chip
h = In ACIS-S3 chip. Spectrum and light curve in Appendix B.
i = Spectrum and light curve in Appendix B.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- OID Optical ID from Hartman+, 2008, J/ApJ/675/1233
8- 16 F9.6 deg RAdeg Right ascension of object (J2000)
18- 26 F9.6 deg DEdeg Declination of object (J2000)
28- 32 F5.2 mag gmag [10.5/25.5]? g magnitude
34- 38 F5.3 mag e_gmag [0.005/0.03]? g magnitude standard deviation
40- 44 F5.2 mag rmag [9.9/24.5]? r magnitude
46- 50 F5.3 mag e_rmag [0.005/0.3]? r magnitude standard deviation
52- 56 F5.2 mag imag [9.3/24.4]? i magnitude
58- 62 F5.3 mag e_imag [0.006/0.04]? i magnitude standard deviation
64- 68 F5.2 d Per [0.04/20]? Rotation period
70- 72 F3.1 --- f_Per ? Rotation period flag (1)
74- 80 F7.3 --- Ps Probability that object is single member
82- 88 F7.3 --- Pb Probability that object is
likely binary member
90- 96 F7.3 --- Pmem Probability that object is member (2)
98-101 F4.2 Msun Mass [0.1/3.8]? Stellar mass
103-108 F6.2 d tau [10.2/185.5]? Convective turnover time
110-120 E11.5 10-7W Lbol ? Bolometric luminosity
122-132 E11.5 10-7W e_Lbol ? Standard deviation of Lbol
134-137 I4 --- XID [1/1013]? ID of X-ray match
139-141 F3.1 arcsec O-X [0/7.2]? Offset between optical object
and X-ray match
143-146 I4 --- ME08 [59/7941]? ID of ME08 (Messina+, 2008,
J/A+A/483/253) match
148-158 F11.8 deg RAMdeg ? Right Ascension of ME08 match (J2000)
160-170 F11.8 deg DEMdeg ? Declination of ME08 match (J2000)
172-182 F11.9 arcsec oME08 [1.5/9.6]? Offset between optical object
and ME08 match
184-188 F5.3 --- OPmem ? Original Pmem (3)
190-193 A4 --- OT Object type from literature (4)
195-205 A11 --- OName Other identification (5)
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Note (1): Rotation period flag as follows:
0 = non-clean HA09 (Hartman+, 2009, J/ApJ/691/342) period
1 = clean HA09 (Hartman+, 2009, J/ApJ/691/342) period
2 = ME08 (Messina+, 2008, J/A+A/483/253) period
Note (2): We used the gi photometry of HA08 (Hartman+, 2008, J/ApJ/675/1233)
for ∼16800 objects with 0.2<(g-i)<4 and combined it with the
stars' distances from M37's center to determine membership
probabilities (Pmem). The full description of our Pmem calculations is
in Appendix A. Stars with 0.2<(g-i)<3.6 were assigned a probability of
being a single star (Ps), a binary star (Pb), or a field (non-member)
star (Pf), so that Ps+Pb+Pf=1 for every star. We considered stars
with pmem=Ps+Pb≥0.2 to be candidate cluster members.
See section 3.3 for further explanations.
Note (3): Pmem<0.2 but we consider it cluster member, based on the fact that it
has a soft X-ray counterpart.
Note (4): Object type as follows:
* = Star from Messina et al. (2008, J/A+A/483/253)
RGB = Red giant from Mermilliod et al. (2008, J/A+A/485/303).
FM06 = Massive star from Frinchaboy & Majewski (2006, J/AJ/136/118).
NS02 = Massive star from Nilakshi & Sagar (2002, J/A+A/381/65).
Note (5): References are:
NS02 = Nilakshi & Sagar (2002, J/A+A/381/65).
FM06 = Frinchaboy & Majewski (2006, J/AJ/136/118).
M08 = Mermilliod et al. (2008, J/A+A/485/303).
K05 = Kalirai et al. (2005ApJ...618L.123K 2005ApJ...618L.123K; <Cl* NGC 2099 KRR NN> in Simbad).
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History:
From electronic version of the journal
References:
Nunez & Agueros Paper II. 2016ApJ...830...44N 2016ApJ...830...44N Cat. J/ApJ/830/44
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Dec-2015