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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
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: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 03 26.0 +49 07 Melotte 20 = NAME alf Perseus cluster ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 44 64 ELODIE individual radial velocities
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
Bytes Format Units Label Explanations
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
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, 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
Acknowledgements: Jean-Claude.Mermilliod(at)
(End) Patricia Vannier [CDS] 30-Jun-2008
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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