J/ApJ/962/12 The Factory and the Beehive. V. (Nunez+, 2024)
The Factory and the Beehive.
V. Chromospheric and coronal activity and its dependence on rotation in Praesepe
and the Hyades.
Nunez A., Agueros M.A., Curtis J.L., Covey K.R., Douglas S.T., Chu S.R.,
DeLaurentiis S., Wang M.(., Drake J.J.
<Astrophys. J., 962, 12 (2024)>
=2024ApJ...962...12N 2024ApJ...962...12N
ADC_Keywords: Clusters, open; Stars, diameters; Spectra, optical;
Equivalent widths; X-ray sources; Infrared
Keywords: Open star clusters ; Stellar chromospheres ; Stellar coronae ; Late-
type stars ; Stellar evolution ; Stellar atmospheres
Abstract:
Low-mass (≲1.2M☉) main-sequence stars lose angular momentum
over time, leading to a decrease in their magnetic activity. The
details of this rotation-activity relation remain poorly understood,
however. Using observations of members of the ∼700Myr old Praesepe and
Hyades open clusters, we aim to characterize the rotation-activity
relation for different tracers of activity at this age. To complement
published data, we obtained new optical spectra for 250 Praesepe
stars, new X-ray detections for 10, and new rotation periods for 28.
These numbers for Hyads are 131, 23, and 137, respectively. The latter
increases the number of Hyads with periods by 50%. We used these data
to measure the fractional Hα and X-ray luminosities,
LHα/Lbol and LX/Lbol, and to calculate Rossby numbers Ro. We
found that at ∼700Myr almost all M dwarfs exhibit Hα emission,
with binaries having the same overall color-Hα equivalent width
distribution as single stars. In the Ro-LHα/Lbol plane,
unsaturated single stars follow a power law with index
β=-5.9±0.8 for Ro>0.3. In the Ro-LX/Lbol plane, we see
evidence for supersaturation for single stars with Ro≲0.01, following
a power law with index βsup=0.5-0.1+0.2, supporting the
hypothesis that the coronae of these stars are being centrifugally
stripped. We found that the critical Ro value at which activity
saturates is smaller for LX/Lbol than for LHα/Lbol. Finally, we
observed an almost 1:1 relation between LHα/Lbol and LX/Lbol,
suggesting that both the corona and the chromosphere experience
similar magnetic heating.
Description:
We adopted the original cluster membership catalog presented in Table2
of Paper IV (Nunez+ 2022, J/ApJ/931/45) for Praesepe and Hyades stars,
updating the Gaia data to the values published in Data Release 3 (DR3;
see I/355). For Praesepe, the catalog has 1739 members, 539 of which
are candidate or confirmed binaries. For Hyades, the numbers are 1315
and 298, respectively. See Section 2.
In Paper II (Douglas+ 2014, J/ApJ/795/161), we presented new spectra
for 130 Hyades and 390 Praesepe members obtained with the MDM
Observatory 2.4m Hiltner telescope and the WIYN 3.5m telescope, both
on Kitt Peak in Arizona and with the Magellan 6.5m Clay telescope, Las
Campanas Observatory in Chile. To these, we added archival spectra.
See Section 3.
We obtained additional spectra of Praesepe and Hyades stars over the
course of 19 observing runs between 2014 November and 2023 March with
the Modular Spectrograph (ModSpec; wavelength coverage of
4500-7500Å and R∼3600) and the Ohio State Multi-Object Spectrograph
(OSMOS; wavelength coverage of 4000-6800Å and R∼9300 in blue and
wavelength coverage of 5500-10000Å and R∼5000 in red) on board the
MDM Observatory 2.4m Hiltner telescope. See Section 3.1.
We obtained additional spectra of Praesepe stars with the multi-object
spectrograph Hectospec on board the MMT 6.5m telescope, Mt. Hopkins in
Arizona (wavelength coverage of 5030-7540Å and R∼11000).
See Section 3.2.
In Paper II, we found SDSS spectra for 66 Praesepe stars (as of 2013
February 14). We repeated this search using the SDSS DR16 Science
Archive Server. We also searched for spectra in the Large Sky Area
Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data Release 8
catalog.
Finally, J. Stauffer (2014, private communication) shared 12 spectra
of Hyades obtained as part of the Stauffer+ (1997ApJ...475..604S 1997ApJ...475..604S)
survey of the cluster. In Paper II, we used 10 of these spectra to
compare our equivalent width measurements to those of Stauffer+ (1997);
here we include all 12 in our spectroscopic sample.
With our newly obtained spectra and newly found archival spectra, we
now have a total of 2216 good quality (S/N≳5) spectra for
879 Praesepe members; for the Hyades, the numbers are 943 and 565,
respectively. Ninety-four of the Praesepe stars and 12 Hyads have five
or more spectra.
See Section 3.3.
Paper IV explains in detail the origin of the X-ray data for our
Praesepe and Hyades stars. Briefly, we consolidated X-ray detections
from the Rontgen Satellite (ROSAT), the Chandra X-ray Observatory
(Chandra), the Neil Gehrels Swift Observatory (Swift), and the X-ray
Multi-Mirror Mission Newton (XMM).
For this work, we updated our X-ray data to reflect developments since
the publication of Paper IV, namely, new Chandra observations,
additions to the Chandra Source Catalog (CSC, see IX/57), and the 13th
data release of the XMM EPIC Serendipitous Source Catalog (4XMM-DR13;
see IX/69).
As part of the Chandra Cool Targets program (Proposal 20201075, PI:
Agueros), we observed 17 Hyads with 14 pointings between 2022 November
and 2023 December. For each observation, we used the ACIS-S3 chip in
Very Faint telemetry mode.
See Section 4.
We measured periods for 19 Praesepe stars and 125 Hyads using TESS
data. We also measured periods for 18 Praesepe stars and 59 Hyads
using ZTF data.
All the ZTF data used in this paper can be found at
doi:10.26131/IRSA539, https://irsa.ipac.caltech.edu/applications/ztf/
See Section 5.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 185 3054 Praesepe and Hyades membership catalog
table4.dat 337 32 Addendum to Table 3 in Paper IV
(Nunez+ 2022, J/ApJ/931/45): the Praespe and
Hyades X-ray source catalog
--------------------------------------------------------------------------------
See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
IX/57 : The Chandra Source Catalog (CSC), Release 2.0 (Evans+, 2019)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
IX/69 : XMM-Newton Serendipitous Source Catalog 4XMM-DR13 (Webb+, 2023)
V/162 : LAMOST DR11 catalogs (Luo+, 2026)
J/ApJS/91/625 : ROSAT survey of the Pleiades (Stauffer+ 1994)
J/AJ/109/1379 : Praesepe & M 67 spectral standards (Allen+ 1995)
J/A+A/397/147 : Activity-rotation relationship in stars (Pizzolato+ 2003)
J/AJ/132/1517 : Spectroscopy of M dwarfs in Praesepe (Kafka+, 2006)
J/ApJ/646/297 : Spitzer obs. of pre-main-sequence stars (Rebull+, 2006)
J/AJ/134/2340 : Membership of Praesepe & Coma Berenices (Kraus+, 2007)
J/MNRAS/407/465 : Fast-rotating M dwarfs in NGC2516 (Jackson+, 2010)
J/MNRAS/411/2099 : Fast-rotating M-dwarf stars in NGC 2547 (Jeffries+, 2011)
J/ApJ/743/48 : Stars with rot. periods & X-ray luminosities (Wright+, 2011)
J/A+A/539/A64 : X-ray data for IC 348 young stars (Alexander+, 2012)
J/ApJS/208/9 : Colors and temperatures of PMS stars (Pecaut+, 2013)
J/MNRAS/431/2063 : UV/X-ray activity of M dwarfs within 10pc (Stelzer+, 2013)
J/ApJ/795/161 : Activity & rot. in Praesepe and the Hyades (Douglas+, 2014)
J/ApJ/809/161 : X-ray obs. and membership of M37 (Nunez+, 2015)
J/A+A/589/A113 : PMS stars in h Per (Argiroffi+, 2016)
J/ApJ/822/47 : K2 rotation periods for 65 Hyades members (Douglas+, 2016)
J/AJ/152/8 : Stellar multiplicity on planetary systems I. (Kraus+, 2016)
J/MNRAS/463/1844 : M dwarfs rotation-activity relation (Stelzer+, 2016)
J/ApJ/842/83 : Praesepe members rot. periods from K2 LCs (Douglas+, 2017)
J/ApJ/834/85 : Hα emission in nearby M dwarfs (Newton+, 2017)
J/ApJ/834/176 : Spectroscopic survey of M37 candidate members (Nunez+, 2017)
J/A+A/616/A10 : Open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)
J/AJ/156/259 : Robo-AO detected close binaries in Gaia DR2 (Ziegler+, 2018)
J/ApJ/879/100 : K2 rot. periods for Hyades & Praesepe (Douglas+, 2019)
J/ApJ/871/193 : Chandra & LAMOST study of stellar activity (He+, 2019)
J/ApJ/872/17 : HAZMAT. V. UV-X-ray evol. of K stars (Richey-Yowell+, 2019)
J/ApJ/904/140 : Ruprecht 147 members & rot. data (Curtis+, 2020)
J/A+A/638/A20 : M dwarfs X-ray activity and rot. relations (Magaudda+, 2020)
J/AJ/159/19 : SOAR TESS survey. I. (Ziegler+, 2020)
J/ApJ/921/167 : Rotators in Praesepe with K2 LCs & Gaia (Rampalli+, 2021)
J/A+A/657/A7 : Stellar & substellar companions from Gaia (Kervella+, 2022)
J/ApJ/931/45 : The factory & the beehive. IV. (Nunez+, 2022)
http://dr16.sdss.org/home : SDSS DR16 homepage
http://dr8.lamost.org/v2/ : LAMOST DR8 homepage
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 28 A28 --- Name Name of star
30- 46 A17 --- 2MASS 2MASS designation (JHHMMSSss+DDMMSSs)
48- 66 I19 --- GaiaDR3 ? Gaia DR3 designation
68- 75 A8 --- Cluster Cluster to which object belongs
("Hyades": 1315 occurrences or
"Praesepe": 1739 occurrences)
77 I1 --- Bin [0/2] Binary flag (2=confirmed binary) (1)
79- 89 A11 mW/m2 FX ? X-ray energy flux in the 0.1-2.4keV band
91- 101 A11 mW/m2 e_FX ? Mean error of X-ray energy flux
103- 107 F5.2 d Prot [0.13/49.32]? Rotation period
109- 114 A6 --- r_Prot Source of Rotation periods (2)
116- 121 F6.2 0.1nm EWHa [-27.7/9.1]? Equivalent width of the H-alpha
line
123- 126 F4.2 0.1nm e_EWHa [0/2.5]? Mean error on EWHa
128- 129 I2 --- Nsp [0/27]? Number of spectra used to calculate
equivalent width
131- 137 F7.3 0.1nm EWHaR [-27.8/1.2]? Relative H-alpha equivalent width
139- 145 F7.1 K Teff [1456/10099]? Effective temperature
147- 151 F5.1 K e_Teff [0.3/530]? Mean error of effective temperature
153- 160 E8.3 --- chi [4.7e-06/9.8e-05]? chi value
162- 169 E8.3 --- e_chi [4.8e-07/1.2e-05]? Mean error of the chi value
171- 177 F7.5 Rsun Rstar [0.087/2.34]? Stellar radius
179- 185 F7.5 Rsun e_Rstar [0/0.24]? Mean error of stellar radius
--------------------------------------------------------------------------------
Note (1): Binary flags as follows:
0 = No binary flag (2239 occurrences)
1 = Candidate binary (501 occurrences)
2 = Confirmed binary (314 occurrences)
Note (2): Source of rotation periods as follows:
TESS = from TESS data
ZTF = from ZTF data
T+Z = from both TESS and ZTF
Legacy = from Douglas+ (2019, J/ApJ/879/100) or Rampalli+ (2021, J/ApJ/921/167)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 I15 --- SourceID ? Catalog Source ID
17- 20 A4 --- XCat Provenance of X-ray information (1)
22- 42 A21 --- Name ? IAU name (JHHMMSS.s+DDMMSS)
44- 52 I9 --- ObsID [12394/871390401]? Observation ID
54- 59 A6 --- Inst Instrument used in the observation
("ACIS-S" or "EPIC")
61- 72 F12.8 deg RAdeg [48.26/130.4] Right ascension (J2000)
74- 85 F12.8 deg DEdeg [-28.7/32.9] Declination (J2000)
87- 98 F12.9 arcsec PosErr [0.07/28.4]? X-ray positional uncertainty
100- 111 F12.9 arcmin OffAxis [0.14/18.51]? Off-axis angle
113- 127 F15.9 --- Det [2.9/40836]? Detection likelihood (2)
129- 142 F14.8 ct NetCtBr [5.87/10114]? Net counts in the broad band
144- 154 F11.9 ct/s CRBr [0.00058/0.5] Net count rate in the broad
band
156- 166 F11.9 ct/s e_CRBr [0.00024/0.009] Mean error of net count rate
in the broad band
168- 178 F11.9 ct/s CRs [0.00035/0.5]? Net count rate in the soft
band
180- 190 F11.9 ct/s e_CRs [0.0002/0.009]? Mean error of net count rate
in the soft band
192- 202 F11.9 ct/s CRh [9.5e-05/0.006]? Net count rate in the hard
band
204- 214 F11.9 ct/s e_CRh [0.0001/0.004]? Mean error of net count rate
in the hard band
216- 223 A8 --- BandBr Definition of broad band in keV
("0.2-12.0" or "0.5-7.0")
225- 231 A7 --- Bands ? Definition of soft band in keV, min-max
("0.2-2.0" or "0.5-2.0")
233- 240 A8 --- Bandh ? Definition of hard band in keV, min-max
("2.0-7.0" or "2.0-12.0")
242- 253 F12.9 --- HR [-1.001/1]? Hardness ratio
(hard-soft)/(hard+soft)
255- 267 F13.6 s ExpTime [4762/116868]? Exposure time
269 I1 --- Var [0/2]? Variability flag (2=Variable) (3)
271- 281 E11.5 mW/m2 FX [3.38e-15/4.85e-13] Unabsorbed X-ray energy
flux in the 0.1-2.4keV band
283- 293 E11.5 mW/m2 e_FX [7.39e-16/3.35e-14] Mean error on FX
295- 297 A3 --- n_FX Source of X-ray energy flux calculation
(always "ECF") (4)
299 I1 --- Fl [0] X-ray flare removed? (always "0")
301 A1 --- Q Quality flag (always empty) (5)
303- 325 A23 --- Match Name of optical counterpart
327- 337 F11.9 arcsec Sep [0.016/9.2] Separation between X-ray source
and optical counterpart
--------------------------------------------------------------------------------
Note (1): Provenance of X-ray information as follows:
4XMM = the 13th data release of the XMM EPIC Serendipitous Source Catalogue
(4XMM-DR13; Webb+ 2020, IX/69).
CIAO = Reduction of Chandra observation with the Chandra Interactive
Analysis of Observations tools
CSC = the Chandra Source Catalog (IX/57)
Note (2): For Chandra (CIAO and CSC), it is the source significance;
for all others, it is the maximum likelihood.
Note (3): Variability flag as follows:
0 = No evidence of variability (28 occurrences)
1 = Possibly variable (2 occurrences)
2 = Definitely variable (2 occurrences)
Note (4): Source of X-ray energy flux calculation as follows:
ECF = From applying ECF (32 occurrences)
SpecFit = From spectral fitting
Note (5): Quality flag as follows:
m = Likely mismatch to optical counterpart
x = Likely extended source
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Agueros et al. Paper I. 2011ApJ...740..110A 2011ApJ...740..110A
Douglas et al. Paper II. 2014ApJ...795..161D 2014ApJ...795..161D Cat. J/ApJ/795/161
Kraus et al. Paper III. 2017ApJ...845...72K 2017ApJ...845...72K Cat. J/ApJ/845/72
Nunez et al. Paper IV. 2022ApJ...931...45N 2022ApJ...931...45N Cat. J/ApJ/931/45
Nunez et al. Paper V. 2024ApJ...962...12N 2024ApJ...962...12N This catalog
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Apr-2026