J/AJ/164/34 epsilon Cnc radial velocities & spectra (Morales+, 2022)
The interferometric binary epsilon Cnc in Praesepe: precise masses and age
Morales L.M., Sandquist E.L., Schaefer G.H., Farrington C.D., Klement R.,
Bedin L.R., Libralato M., Malavolta L., Nardiello D., Orosz J.A.,
Monnier J.D., Kraus S., Le Bouquin J.-B., Anugu N., ten Brummelaar T.,
Davies C.L., Ennis J., Gardner T., Lanthermann C.
<Astron. J., 164, 34 (2022)>
=2022AJ....164...34M 2022AJ....164...34M
ADC_Keywords: Stars, double and multiple; Spectra, optical; Clusters, open
Keywords: Open star clusters ; Spectroscopic binary stars ; White dwarf stars ;
Stellar evolution ; Long baseline interferometry
Abstract:
We observe the brightest member of the Praesepe cluster, ε Cnc,
to precisely measure the characteristics of the stars in this binary
system, en route to a new measurement of the cluster's age. We present
spectroscopic radial velocity measurements and interferometric
observations of the sky-projected orbit to derive the masses, which
we find to be M1/M☉=2.420±0.008 and M2/M☉=2.226±0.004.
We place limits on the color-magnitude positions of the stars by
using spectroscopic and interferometric luminosity ratios while trying
to reproduce the spectral energy distribution of ε Cnc. We
reexamine the cluster membership of stars at the bright end of the
color-magnitude diagram using Gaia data and literature radial velocity
information. The binary star data are consistent with an age of
637±19Myr, as determined from MIST model isochrones. The masses and
luminosities of the stars appear to select models with the most
commonly used amount of convective core overshooting.
Description:
The majority of the radial velocity measurements in this study are
based on a reanalysis of spectra taken as part of a survey of bright
Praesepe stars by Abt & Willmarth in 1999 (J/ApJ/521/682). The spectra
were obtained on the Kitt Peak National Observatory (KPNO) 0.9m coude
feed telescope and spectrograph between 1991 and 1996. The spectra
generally covered the wavelength range 436-474.2nm, at a resolution of
about 0.022nm.
In addition, we extracted two spectra from the archive of the ELODIE
spectrograph at the Observatoire de Haute-Provence (OHP). The spectra
(R=42,000) were taken in 2004 by observer R. Monier, covering the
range 385-681nm.
We also obtained four new spectra in 2020 with the Fiber-fed Echelle
Spectrograph (FIES) on the 2.56m Nordic Optical Telescope (NOT). We
used the medium-resolution (R=46,000) fiber in our observations,
covering the spectral range 370-830nm, although we only used 440-660nm
in our measurements.
Finally, we use one of Plaskett+ (1921PDAO....1..287P 1921PDAO....1..287P) measurements
that were taken at four epochs in 1919 and 1920 from the 1.83 m
Plaskett Telescope at Dominion Astrophysical Observatory (DAO).
Objects:
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RA (2000) DE Designation(s)
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08 40 27.01 +19 32 41.3 epsilon Cnc = 2MASS J08402702+1932415
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table8.dat 64 33 Radial velocity measurements and their associated
spectra for epsilon Cnc A and B
sp/* . 30 Individual MRT file of the KPNO & NOT spectra
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See also:
B/gcvs : General Catalogue of Variable Stars (Samus+, 2007-2017)
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2020)
II/84 : 13-color photometry of 1380 bright stars (Johnson+ 1975)
II/7 : UBVRIJKLMNH Photoelectric Catalogue (Morel+ 1978)
II/97 : ANS UV Catalogue of Point Sources (Wesselius+ 1982)
II/297 : AKARI/IRC mid-IR all-sky Survey (ISAS/JAXA, 2010)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
VII/233 : 2MASS All-Sky Extended Source Cat. (XSC) (IPAC/UMass, 2003-2006)
J/AJ/106/637 : ICCD speckle observations. IX (Mason+, 1993)
J/AJ/108/2299 : ICCD speckle observations of binary stars. XI. (Hartkopf+ 1994)
J/AJ/114/699 : Spectrophotometry in open clusters (Clampitt+ 1997)
J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)
J/A+AS/129/9 : Delta Sct stars in Praesepe (Pena+ 1998)
J/A+A/333/897 : Mass segregation in open clusters (Raboud+ 1998)
J/ApJ/521/682 : Binaries in the Praesepe and Coma clusters (Abt+, 1999)
J/A+AS/137/451 : Radial velocities. IX. (Grenier+, 1999)
J/A+A/354/881 : RVs of Praesepe & Hyades Am stars (Debernardi+ 2000)
J/AJ/119/3084 : ICCD speckle obs. of binary stars. XXIII. (Hartkopf+, 2000)
J/A+A/393/897 : Rotational velocities of A-type stars II. (Royer+, 2002)
J/ApJ/697/1578 : A debris disk study of Praesepe (Gaspar+, 2009)
J/A+A/525/A2 : Eclipsing binaries in NGC6791 (Brogaard+, 2011)
J/A+A/535/A30 : Chem abundance of 12 stars in open clusters (Carrera+, 2011)
J/MNRAS/413/2218 : Stellar rotation in Hyades and Praesepe (Delorme+, 2011)
J/A+A/543/A106 : UBVRI photometry in NGC6791 (Brogaard+, 2012)
J/A+A/546/A61 : Radial velocities for XHIP catalogue (de Bruijne+, 2012)
J/MNRAS/442/2081 : Praesepe members light curves (Kovacs+, 2014)
J/A+A/580/A23 : Stroemgren-Crawford uvbyβ phot. cat. (Paunzen, 2015)
J/AJ/152/213 : Interferometry & spec. of sigma Orionis (Schaefer+, 2016)
J/AJ/153/128 : WOCS. LXXV. Hyades&Praesepe stellar Li data (Cummings+, 2017)
J/ApJ/842/83 : Praesepe members rot. periods from K2 LCs (Douglas+, 2017)
J/AJ/153/212 : Obs. of binary stars at the WIYN telescope (Horch+, 2017)
J/AJ/154/110 : Orbits from SOAR speckle interferometry. II. (Tokovinin, 2017)
J/A+A/618/A93 : Gaia DR2 open clusters in the Milky Way (Cantat-Gaudin+, 2018)
J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)
J/ApJ/879/100 : K2 rot. periods for Hyades & Praesepe members (Douglas+, 2019)
J/A+A/627/A4 : Praesepe (NGC 2632) and its tidal tails (Roeser+, 2019)
J/A+A/621/L2 : Hyades tidal tails revealed by Gaia DR2 (Roeser+, 2019)
J/A+A/633/A38 : EW of 10 solar-type stars of Praesepe (D'Orazi+, 2020)
J/ApJ/919/100 : Abundances of 6 stars in Praesepe cluster (Vejar+, 2021)
Byte-by-byte Description of file:table8.dat
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Bytes Format Units Label Explanations
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1- 11 F11.5 d MJD [22384/58969] Modified Julian Date (1)
13- 17 F5.1 km/s RVelA [-27.9/86.1] Radial velocity of ε Cnc A
19- 21 F3.1 km/s e_RVelA [0.1/3] RVelA uncertainty
23- 27 F5.1 km/s RVelB [-20.5/95.6] Radial velocity of ε Cnc B
29- 31 F3.1 km/s e_RVelB [1.3/4.1] RVelB uncertainty
33- 37 F5.3 --- Phase [0.06/0.94] Orbital phase
39- 42 A4 --- Tel Telescope used for the observation (2)
44- 45 A2 --- Sp Associated spectrum at MJD with link to
interactive plot (column added by CDS)
47- 64 A18 --- File Link to the spectrum file in MRT format (column
added by CDS)
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Note (1): MJD = HJD - 2,400,000
Note (2): Telescopes and instruments as follows:
KPNO = Kitt Peak National Observatory (KPNO) 0.9m coude feed telescope and
spectrograph, located southwest of Tucson, Arizona.
NOT = The 2.56m Nordic Optical Telescope (NOT) with the Fiber-fed Echelle
Spectrograph (FIES), located at Roque de los Muchachos Observatory,
La Palma in the Canary Islands.
OHP = The 1.93m telescope at the Observatoire de Haute-Provence (OHP) with
the ELODIE spectrograph, located in France.
DAO = The 1.83m Plaskett Telescope at Dominion Astrophysical Observatory (DAO)
located in Saanich, British Columbia, Canada.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 23-Sep-2025