J/A+A/488/409 Radial velocities of α Per stars (Mermilliod+, 2008)
Membership and binarity of solar-type dwarfs in the nearby open cluster
Alpha Persei (Mel 20).
Mermilliod J.-C., Queloz D., Mayor M.
<Astron. Astrophys. 488, 409 (2008)>
=2008A&A...488..409M 2008A&A...488..409M
ADC_Keywords: Clusters, open ; Radial velocities
Keywords: stars: binary: spectroscopic - Galaxy: open cluster and associations:
individual: Alpha Persei (Melotte 20) - technique: radial velocity
Abstract:
The Alpha Persei open cluster (Melotte 20) is one of the nearby
clusters (d<500pc) for which a long-term systematic radial-velocity
monitoring of the solar-type stars has not been published so far.
We undertook an observing program in 1982 to study the membership,
duplicity, and rotation of the main-sequence stars and to compare the
results with those of the other nearby clusters.
Radial-velocity observations of 60 solar-type stars in Mel 20 were
obtained with CORAVEL, and of 44 fainter stars with ELODIE
spectrographs, in the magnitude range 9.5<V<13.85
The membership of 37 stars from the list compiled by Heckmann is
confirmed according to their proper motions, radial velocities, and
photometry. We discovered twelve spectroscopic binaries (3
double-lined, 8 single-lined, 1 suspected) among the members and
determined an orbit for the double-lined binary He 848.
The observed frequency of spectroscopic binaries is therefore 32%
(12/37). Four stars are photometric binaries.
In addition, the membership of 33 stars with AP numbers is supported
by the present radial velocities.
Two single-lined and three double-lined binaries were detected in this
sample. The cluster mean radial velocity is -1.39±0.17km/s based on
18 stars within 2σ.
We found a systematic difference of 3.67±1.48km/s between observed-
and astrometric radial velocities.
The Alpha Persei cluster members define a tight main sequence in the
colour-magnitude diagrams. The remaining scatter observed in the
colour- magnitude diagrams and in radial velocities may be due to the
difficulty of separating the core Alpha Persei stars from the extended
comoving stream.
Objects:
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RA (2000) DE Designation(s)
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03 26.0 +49 07 Melotte 20 = NAME alf Perseus cluster
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 44 64 ELODIE individual radial velocities
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See also:
III/55 : Radial Velocities in Open Clusters (Mermilliod 1979)
III/97 : Radial Velocities in open clusters (Mermilliod 1984)
V/80 : Low-Mass Stars Membership in Alpha Persei Cluster (Prosser 1992)
J/AN/283/109 : Star positions in the region of alpha Per (Heckmann+, 1956)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- No Star designation (WEBDA) (1)
9- 19 F11.3 d HJD Heliocentric Julian date
25 A1 ---- m_No [AB 12] Component (2)
32- 37 F6.2 km/s RV Radial velocity
41- 44 F4.2 km/s e_RV Error on the radial velocity
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Note (1): Star number are from:
No 1-1234 : Heckmann et al., 1956, Cat. J/AN/283/109,
Cl Melotte 20 NNNN in Simbad
No > 1500 : Prosser, 1992AJ....103..488P 1992AJ....103..488P, Cat. V/80,
Cl* Melotte 20 AP NNN in Simbad, where NNN is No-1500
Note (2): A, B stand for components of doubled-lined binaries
1, 2 stand for components of visual binaries
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Acknowledgements:
Jean-Claude.Mermilliod(at)obs.unige.ch
(End) Patricia Vannier [CDS] 30-Jun-2008