J/A+AS/123/63 NGC 6530 multiwavelength photometry (van den Ancker+ 1997) ================================================================================ A multiwavelength study of star formation in the very young open cluster NGC 6530 van den Ancker M.E., The P.S., Feinstein A., Vazquez R.A., de Winter D., Perez M.R. =1997A&AS..123...63V (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Clusters, open ; Photometry Keywords: circumstellar matter - stars: formation - stars: pre-main sequence - dust, extinction - H II regions - open clusters and associations: NGC 6530 Description: The distance and formation history of the very young open cluster NGC 6530 were investigated by studying a total of 132 probable member stars of this open cluster. It was concluded that the distance to NGC 6530 is 1.8+/-0.2kpc, and its interstellar reddening E(B-V) is 0.30. Furthermore, we conclude that the extinction law of the intracluster material is normal (i.e. R_V=3.1), but anomalous extinction laws were found for several more embedded stars in the cluster. Of the 132 stars included in this study, 11 are suspected to be variable, five show Halpha in emission and nine show an infrared excess. Among the member stars of NGC 6530, three were found to be part of the Herbig Ae/Be stellar class, whereas two others are possible members of this stellar group as well. Also, one cluster member is probably a new massive post-AGB star, whereas the same could possibly apply to another member star. Finally, from the distribution of post- and pre-main sequence stars in the cluster's HR-diagram, it was concluded that the process of star formation in NGC 6530 must have started a few times 10^7 years ago and, for the less massive stars, is probably still going on today. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1 95 132 Properties of programme stars in NGC 6530 from literature table2 129 105 New photometric data of stars in NGC 6530 table5 91 130 Astrophysical parameters of stars in NGC 6530 -------------------------------------------------------------------------------- Byte-by-byte Description of file: table1 -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 A3 --- VAJ Star number by van Altena & Jones (1972A&A....20..425V) 6- 8 A3 --- Walk Star number by Walker (1957ApJ...125..636W) and Kilambi (1977MNRAS.178..423K) 10- 12 A3 --- Sag Star number by Sagar & Joshi (1978MNRAS.184..467S) 15- 27 A13 --- Other Other designation 29- 30 I2 h RAh Right ascension (J1950) 32- 33 I2 min RAm Right ascension (J1950) 35- 38 F4.1 s RAs Right ascension (J1950) 41 A1 --- DE- Declination sign 42- 43 I2 deg DEd Declination (J1950) 45- 46 I2 arcmin DEm Declination (J1950) 48- 49 I2 arcsec DEs Declination (J1950) 52- 53 I2 % Prob ? Proper motion membership probability 56- 60 F5.2 mag Vmag V magnitude 63- 66 F4.2 mag B-V ? B-V colour index 69- 73 F5.2 mag U-B ? U-B colour index 76- 80 F5.1 km/s HRV ? Heliocentric radial velocity 83- 93 A11 --- Sp Spectral type 95 A1 --- Ref. Reference for spectral type (1) -------------------------------------------------------------------------------- Note (1): 1: Buscombe 1984, See Cat. 2: Boggs & Boehm-Vitense (1989ApJ...339..209B) 3: Walker (1957ApJ...125..636W) 4: Johnson & Borgman (1963BAN....17..115J) 5: Hiltner et al. (1965ApJ...141..183H) 6: Torres (1987ApJ...322..949T) 7: Boesono et al. (1987Ap&SS.137..167B) 8: Morrison & Conti (1978ApJ...224..558M) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2 -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- No. Star number for new stars 6- 11 F6.3 --- Vmag ? Walraven V intensity 14- 18 F5.2 mag Vmag1 ? Johnson V magnitude computed from Walraven V and V-B 21- 25 F5.3 --- V-B ? Walraven V-B colour index 28- 32 F5.3 --- B-U ? Walraven B-U colour index 34- 39 F6.3 --- U-W ? Walraven U-W colour index 42- 46 F5.3 --- B-L ? Walraven D-L colour index 49- 55 A7 --- Date1 Date (dd/mm/yy) of Walraven measurement 58- 62 F5.2 mag Vmag2 ? Johnson V magnitude 65- 68 F4.2 mag B-V ? Johnson B-V colour index 71- 75 F5.2 mag U-B ? Johnson U-B colour index 78- 81 F4.2 mag V-R ? Cousins V-R colour index 84- 87 F4.2 mag V-I ? Cousins V-I colour index 90- 96 A7 --- Date2 Date (dd/mm/yy) of UBVRI measurement 99-103 F5.2 mag Jmag ? ESO J magnitude index 106-110 F5.2 mag Hmag ? ESO H magnitude index 113-117 F5.2 mag Kmag ? ESO K magnitude index 120-126 A7 --- Date3 Date (dd/mm/yy) of JHK measurement 129 A1 --- Remark [1/2] Remarks (1) -------------------------------------------------------------------------------- Note (1): 1: Probably a variable star. 2: Two sources at that position in the infrared. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table5 -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- No. Star number 6- 13 A8 --- SpUBVl Spectral type from UBV data from literature 15- 22 A8 --- SpUBVn Spectral type from new UBV data 24- 31 A8 --- SpWalr Spectral type from new Walraven data 33- 37 A5 --- SpIDS Spectral type from IDS spectrum 40- 44 A5 --- SpCCD Spectral type from CCD spectrum 48- 54 A7 --- SpAdop Adopted spectral type 57- 60 F4.2 mag E(B-V) B-V colour excess 63- 65 F3.1 --- Extinct ? Ratio of visual to selective extinction 66 A1 --- u_Extinct Uncertainty flag on extinct 68- 71 F4.2 kpc Dist Photometric distance 74- 78 F5.3 K logTeff log of effective temperature 81- 85 F5.3 solLum logL log of stellar luminosity 88- 91 A4 --- IRexcess Presence of infrared excess (YES/NO) -------------------------------------------------------------------------------- Acknowledgements: Mario van den Ancker References: van Altena W.F., Jones B.F. 1972, A&A 20, 425 =1972A&A....20..425V Boesono B., The, P.S., Tjin A Djie, H.R.E. 1987, Ap&SS 137, 167 =1987Ap&SS.137..167B Boggs D., Boehm-Vitense E. 1989, ApJ 339, 209 =1989ApJ...339..209B Buscombe W. 1984, Sixth General Catalogue of MK Spectral Classifications, Northwestern University, Evanston, Illinois =Catalogue Hiltner W.A., Morgan W.W., Neff J.S. 1965, ApJ 141, 183 =1965ApJ...141..183H Johnson H.L., Borgman J. 1963, B.A.N. 17, 115 =1963BAN....17..115J Kilambi G.C. 1977, MNRAS 178, 423 =1977MNRAS.178..423K Morrison N.D., Conti P.S. 1978, ApJ 224, 558 =1978ApJ...224..558M Sagar R., Joshi U.C. 1978, MNRAS 184, 467 =1978MNRAS.184..467S Torres A.V. 1987, ApJ 322, 949 =1987ApJ...322..949T Walker M.F. 1957, ApJ 125, 636 =1957ApJ...125..636W ================================================================================ (End) Patricia Bauer [CDS] 13-Sep-1996