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J/ApJ/443/124               Radial Velocities of Stars in M4    (Peterson+ 1995)

Radial Velocities of Stars in the Globular Cluster M4 and the Cluster Distance Peterson R.C., Rees R.F., Cudworth K.M. <Astrophys. J. 443, 124 (1995)> =1995ApJ...443..124P
ADC_Keywords: Clusters, globular; Radial velocities; Positional data; Photometry Keywords: globular clusters: individual (M4) - stars: kinematics - techniques: radial velocities Abstract: The internal stellar velocity distribution of the globular cluster M4 is evaluated from nearly 200 new radial velocity measurements good to 1 km/s and a rederivation of existing proper motions. The mean radial velocity of the cluster is 70.9 ± 0.6 km/s. The velocity dispersion is 3.5 ± 0.3 km/s at the core, dropping marginally towards the outskirts. Such a low internal dispersion is somewhat at odds with the cluster's orbit, for which the perigalacticon is sufficiently close to the galactic center that the probability of cluster disruption is high; a tidal radius two-thirds the currently accepted value would eliminate the discrepancy. The cluster mass-to-light ratio is also small, M/L_V = 1.0 ± 0.4 in solar units. M4 thus joins M22 as a cluster of moderate mass and concentration with a mass-to-light ratio among the lowest known. The astrometric distance to the cluster is also smaller than expected, 1.72 ± 0.14 kpc. This is only consistent with conventional estimates of the luminosity of horizontal branch stars provided an extinction law R = A_V/E(B-V) ∼ 4 is adopted, as has been suggested recently by several authors. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 88 182 Velocities for M4 members table2.dat 85 11 *Velocities for M4 nonmembers table3.dat 28 93 Duplicate velocities table5.dat 68 531 Proper-motion data superseding Table 3 of Cudworth & Rees =1990AJ.....99.1491C
Note on table2.dat: Table 2 lists the same information as in Table 1 for the nonmembers of M4. The velocities of these stars average -12.8 km/s with a dispersion of 34.5 km/s. Thus the radial velocity of M4 is quite distinct from that of the field, differing by more than 80 km/s.
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 2 I2 h RAh Right ascension (equinox 1950.0) 4- 5 I2 min RAm R.A. 7- 11 F5.2 s RAs R.A. 13 A1 --- DE- Declination sign 14- 15 I2 deg DEd Declination (equinox 1950.0) 17- 18 I2 arcmin DEm Dec. 20- 23 F4.1 arcsec DEs Dec. 25- 29 F5.2 arcmin Dist Radial distance from cluster center 31- 35 F5.1 deg PA Position angle positive north through east 38- 42 F5.2 mag Vmag V magnitude 43- 47 F5.2 mag B-V B-V color 50- 59 F10.2 d Date *Julian date of each observation 62- 66 F5.2 km/s RV *Measured radial velocity 67- 71 F5.2 km/s e_RV *Internal uncertainty in RV 72- 74 I3 % Memb []?=-1 Percent probability of membership 77- 88 A12 --- ID *Identification
Note on Date: Julian date of each observation, or that of the first observation if the star was observed twice or more. Note on RV: For all multiply observed stars, this is the weighted mean of the set of observations in Table 3. Note on e_RV: The uncertainty is derived from the ratio R of the height of the cross-correlation peak relative to a typical noise fluctuation, according to the Tonry & Davis [1979, AJ, 84, 1511] formula sigma_R = K/(1+R) (in km/s), with K=8.3 for sharp-lined spectra obtained with the Mount Hopkins echelle spectrographs. Note on ID: Star Name: Lee (1977, A&AS, 27, 367) number, no prefix; Sawyer-Hogg (1973, Pub. DDO, 3, No. 6) variable, prefix V; Alcaino (1975, A&AS, 21, 5) single letter or prefix A; Greenstein (1939, ApJ, 90, 387) prefix G
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 2 I2 h RAh Right ascension (equinox 1950.0) 4- 5 I2 min RAm R.A. 7- 11 F5.2 s RAs R.A. 13 A1 --- DE- Declination sign 14- 15 I2 deg DEd Declination (equinox 1950.0) 17- 18 I2 arcmin DEm Dec. 20- 23 F4.1 arcsec DEs Dec. 24- 29 F6.2 arcmin Dist Radial distance from cluster center 31- 35 F5.1 deg PA Position angle positive north through east 38- 42 F5.2 mag Vmag V magnitude 43- 47 F5.2 mag B-V B-V color 50- 59 F10.2 d Date Julian date of each observation 61- 66 F6.2 km/s RV Measured radial velocity 68- 71 F4.2 km/s e_RV Internal uncertainty in RV 72- 74 I3 % Memb []? Percent probability of membership 77- 85 A9 --- ID Identification
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 10 F10.2 d Date Julian date of each observation 12- 17 F6.2 km/s RV Measured radial velocity 19- 22 F4.2 km/s e_RV Internal uncertainty in RV 25- 28 A4 --- ID Number from Lee 1977, A&AS, 27, 367
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 16 A16 --- Names *Star names 18- 24 F7.1 arcsec X *X coordinate relative to cluster center 25- 31 F7.1 arcsec Y *Y coordinate relative to cluster center 32- 37 I6 0.01mas/yr mu_x Relative proper motion in X coordinate 38- 41 I4 0.01mas/yr emux Standard error in mu_x 42- 47 I6 0.01mas/yr mu_y Relative proper motion in Y coordinate 48- 51 I4 0.01mas/yr emuy Standard error in mu_y 52- 58 F7.2 mag Vmag V magnitude 59- 64 F6.2 mag B-V B-V color 65- 68 I4 % Pr Probability of membership based on relative proper motion
Note on Names: Lee (1977, A&AS, 27, 367) number, no prefix; Sawyer-Hogg (1973, Pub. DDO, 3, No. 6) variable, prefix V; Alcaino (1975, A&AS, 21 5), single letter or prefix A; Alcaino and Liller (1984), AL -- second number is ring number; Zinn et al. (1972) UV-bright star, Z; Greenstein (1939, ApJ, 90, 387), prefix G Note on X, Y: X and Y coordinates (arcsec) relative to the cluster center of Shawl and White (1986, AJ, 91, 312) and oriented along right ascension and declination for equator and equinox 1950
Origin: AAS CD-ROM series, Volume 4, 1995 Lee Brotzman [ADS] 06-May-1995 Historical Notes: the Julian Dates were converted to absolute scale (initially with offset 2440000)
(End) [CDS] 11-Jul-1995
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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