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J/ApJ/448/683 Hyades RASS observations (Stern+ 1995)
ROSAT all-sky survey observations of the Hyades cluster Stern R.A., Schmitt J.H.M.M., Kahabka P.T. <Astrophys. J. 448, 683 (1995)> =1995ApJ...448..683S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Binaries, X-ray Mission_Name: ROSAT Keywords: binaries: close - surveys - X-rays: stars - open clusters and associations: individual (Hyades) Abstract: We report the results of a complete X-ray survey of the Hyades cluster region using the ROSAT All-Sky Survey (RASS). Our survey covers over 900deg2 of the sky. Over 185 optically identified Hyades were detected down to a limiting X-ray luminosity of ∼1-2x1028ergs/s (0.1-1.8keV); among solar-like stars, i.e., main-sequence stars of spectral type G, the RASS detection rate is ∼90%. The presence of many binary systems in the cluster is a key factor influencing the X-ray luminosity function. Short-period (∼ a few days or less) binaries are anomalously X-ray bright, as might be expected; however, the X-ray luminosity functions of K and possibly M binaries of all types are significantly different from their single counterparts, confirming the results of Pye et al. (1994MNRAS.266..798P) for a smaller K star sample drawn from deep ROSAT pointings. Comparison with Einstein Observatory studies of a subset of Hyades stars demonstrates a general lack of significant (> a factor of 2) long-term X-ray variability. This may be the result of the dominance of a small-scale, turbulent dynamo in the younger Hyades stars compared to the large-scale, cyclic dynamo observed in the Sun. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1 104 440 Hyades survey table2 83 4 Reid (1992, Cat. J/MNRAS/257/257) stars detected in X-rays table3 70 20 Non-members in optical catalog detected in X-rays
See also: IX/11 : The ROSAT Source Catalogue (Voges+ 1995) Byte-by-byte Description of file: table1
Bytes Format Units Label Explanations
1- 10 A10 --- Star Star name (1) 12- 13 I2 h RAh Optical right ascension (J2000) 15- 16 I2 min RAm Optical right ascension (J2000) 18- 21 F4.1 s RAs Optical right ascension (J2000) 23- 24 I2 deg DEd Optical declination (J2000) 26- 27 I2 arcmin DEm Optical declination (J2000) 29- 32 F4.1 arcsec DEs Optical declination (J2000) 34- 37 F4.1 arcsec X-Opos ? Difference in X-ray and optical positions 39- 43 F5.2 mag Vmag ? V magnitude 45- 46 I2 --- r_Vmag ? Reference for V magnitude (2) 48- 52 F5.2 mag B-V ? B-V colour index 54- 55 I2 --- r_B-V ? Reference for B-V index (2) 57- 60 F4.1 pc Dist ? Distance 62 A1 --- r_Dist [HS] Reference for distance (3) 65- 74 A10 --- Binarity Binarity codes (4) 76- 81 F6.1 --- M/L ? Maximum likelihood ratio for X-ray source existence 83 A1 --- l_LX45 Limit flag on LX45 84- 88 F5.1 ZW LX45 X-ray luminosity based upon an assumed 45pc distance 90- 93 F4.1 ZW e_LX45 ? rms uncertainty on LX45 95 A1 --- l_LXd Limt flag on LXd 96-100 F5.1 ZW LXd ? X-ray luminosity using the distance from Dist column 102-104 F3.1 ZW e_LXd ? rms uncertainty on LXd
Note (1): For members with multiple designations, the name used is determined by the following order of preference: vB (van Bueren, 1952BAN....11..385V), VA (van Altena, 1969AJ.....74....2V), BD (Bonner Durchmusterung, Cat. I/122), GH 7 or GH 8 (Giclas, Burnham, & Thomas, 1962LowOB...5..257G), L (Pels et al., 1975A&A....43..423P), LP (Luyten et al., 1981, see Cat. I/130), H (Hanson 1975, Cat. J/AJ/80/379), OS (Osvald, 1954AN....281..193O), AK (Artyukhina & Khopolov 1975, Trans. Gos. Astron. Inst. Sternberg, 46 No. 2, 57 and 1976, Trans. Gos. Astron. Inst. Sternberg, 47 ,105) HD, or other designation. A table of cross-referenced Hyades members provided by E. Weis was used in selecting the primary designation. Note (2): Optical photometry references are as follows: (1)-(3) Weis & Hanson, 1988AJ.....96..148W (4)-(6) Upgren et al., 1985AJ.....90.2039U (7) Weis, 1983PASP...95...29W (8)-(9) Weis & Upgren, 1982PASP...94..475W (10) Stauffer, 1982AJ.....87..899S (11) Weis et al., 1979PASP...91..766W (12)-(13) Weis, 1992, unpublished photometry; (14) Pels et al., 1975A&A....43..423P (15) Eggen, 1969ApJ...157..287E (16) Morel & Mangnenat, 1978, Cat. II/7 (17) Schwan, 1991A&A...243..386 (18) Reid, 1992, Cat. J/MNRAS/257/257 (19) Hanson, 1975, Cat. J/AJ/80/379 (20) Griffin et al., 1988AJ.....96..172G Note (3): H: Hanson, 1975, Cat. J/AJ/80/379 S: Schwan, 1991A&A...243..386 Note (4): Binary notations: GR: spectroscopic binary as noted in Griffin et al., 1988AJ.....96..172G GP: photometric binary as noted in Griffin et al., 1988AJ.....96..172G GV: visual binary as noted in Griffin et al., 1988AJ.....96..172G B: spectroscopic binary listed in Batten et al., 1989, Cat. V/64 C: photometric binary from Carney, 1982AJ.....87.1527C T: photometric binary as noted by Bettis, 1975 (reference not precised) S: photometric binary as noted by Stauffer, 1982AJ.....87..899S UW: photometric binary as noted by Upgren & Weis, 1977AJ.....82..978U A: visual binary in ADS catalog MD: definite speckle binary in Mason et al., 1993AJ....105..220M MP: probable speckle binary in Mason et al., 1993AJ....105..220M MS: suspected speckle binary in Mason et al., 1993AJ....105..220M SP: spectroscopic binary or triple based on unpublished data (Stauffer, private communication).
Byte-by-byte Description of file: table2
Bytes Format Units Label Explanations
1- 5 A5 --- Star Star designation (Reid number, Cat. J/MNRAS/257/257) 7 I1 h RAh Optical right ascension (J2000) 9- 10 I2 min RAm Optical right ascension (J2000) 12- 15 F4.1 s RAs Optical right ascension (J2000) 17- 18 I2 deg DEd Optical declination (J2000) 20- 21 I2 arcmin DEm Optical declination (J2000) 23- 26 F4.1 arcsec DEs Optical declination (J2000) 28- 32 F5.2 mag Vmag ? V magnitude 34- 37 F4.2 mag B-V ? B-V colour index 39- 42 F4.1 --- M/L ? Maximum likelihood ratio for X-ray source existence 44- 48 F5.3 ct/s PSPC PSPC count 50- 54 F5.3 ct/s e_PSPC rms uncertainty on PSPC 56- 59 F4.1 arcsec X-Opos ? Difference in X-ray and optical positions 61- 83 A23 --- Note Notes
Byte-by-byte Description of file: table3
Bytes Format Units Label Explanations
1- 10 A10 --- Star Star name 12- 13 I2 h RAh Optical right ascension (J2000) 15- 16 I2 min RAm Optical right ascension (J2000) 18- 21 F4.1 s RAs Optical right ascension (J2000) 23- 24 I2 deg DEd Optical declination (J2000) 26- 27 I2 arcmin DEm Optical declination (J2000) 29- 32 F4.1 arcsec DEs Optical declination (J2000) 34- 38 F5.2 mag Vmag ? V magnitude 40- 43 F4.2 mag B-V ? B-V colour index 45- 46 A2 --- Binarity Binarity codes (1) 48- 53 F6.1 --- M/L ? Maximum likelihood ratio for X-ray source existence 55- 59 F5.3 ct/s PSPC PSPC count 61- 65 F5.3 ct/s e_PSPC rms uncertainty on PSPC 67- 70 F4.1 arcsec X-Opos ? Difference in X-ray and optical positions
Note (1): Binary notations: GR: spectroscopic binary as noted in Griffin et al., 1988AJ.....96..172G UW: photometric binary as noted by Upgren & Weis, 1977AJ.....82..978U
History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 08-Apr-1997
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