J/ApJ/795/161 Activity and rotation in Praesepe and the Hyades (Douglas+, 2014)
The factory and the beehive.
II. Activity and rotation in Praesepe and the Hyades.
Douglas S.T., Agueros M.A., Covey K.R., Bowsher E.C., Bochanski J.J.,
Cargile P.A., Kraus A., Law N.M., Lemonias J.J., Arce H.G., Fierroz D.F.,
Kundert A.
<Astrophys. J., 795, 161 (2014)>
=2014ApJ...795..161D 2014ApJ...795..161D (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Spectral types ; Photometry, infrared ;
Stars, masses ; Stars, distances ; Equivalent widths
Keywords: stars: activity - stars: chromospheres - stars: coronae -
stars: evolution - stars: late-type - stars: rotation
Abstract:
Open clusters are collections of stars with a single, well-determined
age, and can be used to investigate the connections between
angular-momentum evolution and magnetic activity over a star's
lifetime. We present the results of a comparative study of the
relationship between stellar rotation and activity in two benchmark
open clusters: Praesepe and the Hyades. As they have the same age and
roughly solar metallicity, these clusters serve as an ideal laboratory
for testing the agreement between theoretical and empirical
rotation-activity relations at ∼600 Myr. We have compiled a
sample of 720 spectra - more than half of which are new
observations - for 516 high-confidence members of Praesepe; we have
also obtained 139 new spectra for 130 high-confidence Hyads. We have
also collected rotation periods (Prot) for 135 Praesepe members and
87 Hyads. To compare Hα emission, an indicator of chromospheric
activity, as a function of color, mass, and Rossby number Ro, we
first calculate an expanded set of χ values, with which we can
obtain the Hα to bolometric luminosity ratio, LHα/Lbol,
even when spectra are not flux-calibrated and/or stars lack reliable
distances. Our χ values cover a broader range of stellar masses
and colors (roughly equivalent to spectral types from K0 to M9), and
exhibit better agreement between independent calculations, than
existing values. Unlike previous authors, we find no difference
between the two clusters in their Hα equivalent width or
LHα/Lbol distributions, and therefore take the merged
Hα and Prot data to be representative of 600 Myr old stars.
Our analysis shows that Hα activity in these stars is saturated
for RO≤0.110.03_+0.02. Above that value activity declines as
a power-law with slope β=0.73-0.12+0.16, before dropping
off rapidly at Ro~ 0.4. These data provide a useful anchor
for calibrating the age-activity-rotation relation beyond 600 Myr.
Description:
Kraus & Hillenbrand (2007, J/AJ/134/2340) calculated proper motions
and photometry for several million objects within 7° of the center
of Praesepe. The resulting catalog includes 1128 candidate cluster
members with membership probabilities Pmem>50%. As in Paper I
(Agueros et al. 2011ApJ...740..110A 2011ApJ...740..110A), we supplement this catalog with
41 known members that are too bright to be identified as members by
Kraus & Hillenbrand (2007, J/AJ/134/2340). For the Hyades, we adopt
the Roser et al. (2011, J/A+A/531/A92) membership catalog. These
authors identified candidate Hyades members via the convergent point
method and confirmed membership using photometry. We used the MDM
Observatory Modular Spectrograph (ModSpec) on the Hiltner 2.4 m telescope
to obtain spectra of stars in Praesepe and the Hyades over the course
of five multi-night runs between 2010 December 2 and 2012 November 14.
Objects:
------------------------------------------------------------
RA (ICRS) DE Designation(s)
------------------------------------------------------------
08 40 24 +19 40.0 Praesepe = NGC 2632
04 26 54.00 +15 52 00.0 Hyades = NAME Hyades Cluster
------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table5.dat 171 1169 Praesepe stars
table6.dat 171 737 Hyades stars
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See also:
J/AJ/80/379 : Hyades cluster: motion, membership, and distance
(Hanson+, 1975)
J/A+A/310/879 : Hyades binaries (Barrado+, 1996)
J/ApJ/521/682 : Binaries in the Praesepe and Coma clusters (Abt+, 1999)
J/A+A/367/111 : A Hipparcos study of the Hyades cluster (de Bruijne+, 2001)
J/A+A/375/989 : JHK photometry of Praesepe low-mass stars (Bouvier+, 2001)
J/AJ/134/2340 : Membership of Praesepe and Coma Berenices clusters
(Kraus+, 2007)
J/A+A/531/A92 : Deep all-sky census of the Hyades (Roeser+, 2011)
J/MNRAS/413/2218 : Stellar rotation in Hyades and Praesepe (Delorme+, 2011)
J/A+A/559/A43 : Pan-STARRS1 (PS1) observations of the Hyades
(Goldman+, 2013)
J/MNRAS/434/3236 : Masses of Praesepe members (Khalaj+, 2013)
Byte-by-byte Description of file: table5.dat table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 22 A22 --- Name Identifier
24- 25 I2 h RAh Hour of Right Ascension (J2000) (4)
27- 28 I2 min RAm Minute of Right Ascension (J2000)
30- 34 F5.2 s RAs Second of Right Ascension (J2000)
36 A1 --- DE- Sign of the Declination (J2000) (4)
37- 38 I2 deg DEd Degree of Declination (J2000) (4)
40- 41 I2 arcmin DEm Arcminute of Declination (J2000)
43- 47 F5.2 arcsec DEs Arcsecond of Declination (J2000)
49- 53 I5 % PMem ?=-9999 Membership probability (1)
55- 59 A5 --- SpType Spectral type
61- 67 F7.3 mag rmag ?=-99 The r' band magnitude (1)
69- 73 F5.3 mag e_rmag ?=9 Error in rmag (1)
75 A1 --- r_rmag [TUSC] Reference for rmag (2)
77- 83 F7.3 mag Kmag ?=-99 The K band magnitude (1)
85- 91 F7.3 mag e_Kmag ?=9 Error in Kmag (1)
93- 96 F4.1 pc Dist ? Distance
98 A1 --- r_Dist [RH-] Reference for Dist (3)
100-107 F8.2 Msun PMass ? Mass from Agueros et al.
(2011ApJ...740..110A 2011ApJ...740..110A) (1)
109-114 F6.2 Msun Mass ?=-99 Mass from this work (1)
116-125 F10.4 Rsun Radius ?=-9999 Radius
127 A1 --- Bin? [YN] Possible binary system
129-131 A3 --- SpTypeH Spectral type from the output of the Hammer
(only in table6.dat)
133-141 F9.3 0.1nm EW ?=-9999 Hα equivalent width; Angstroms
(1)
143-151 F9.3 0.1nm e_EW ?=-9999 Error in EW (1)
153-161 F9.3 10-5 Lum ?=-9999 Hα to bolometric luminosities
ratio for stars with Hα in emission (1)
163-171 F9.3 10-5 e_Lum ?=-9999 Error in Lum (1)
--------------------------------------------------------------------------------
Note (1): Where a -9999 indicates a null value.
Note (2): Reference as follows:
T = 2MASS/TYCHO2;
U = UCAC4;
S = SDSS;
C = CMC14.
Note (3): Reference as follows:
R = Secular parallax from Roeser et al. 2011, J/A+A/531/A92;
H = Hipparcos parallax;
- = No parallax available.
Note (4): 35 coordinates with discrepancies between names and declination
(for all 2MASS names with declination sign <0) have been corrected
by CDS.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
31-May-2017: Insert into VizieR
09-Jun-2023: 35 declinations in Table 6 corrected for the ones given
in names (concerned all 2MASS objects with declination sign <0).
References:
Agueros et al. Paper I. 2011ApJ...740..110A 2011ApJ...740..110A
Douglas et al. Paper II. 2014ApJ...795..161D 2014ApJ...795..161D This catalog
Kraus et al. Paper III. 2017ApJ...845...72K 2017ApJ...845...72K
Douglas et al. 2017ApJ...842...83D 2017ApJ...842...83D Cat. J/ApJ/842/83
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 24-May-2017