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J/AJ/116/1801       IC 4996 CCD photometry                   (Delgado+, 1998)

Pre-main-sequence stars in the young galactic cluster IC 4996: a CCD photometric study. Delgado A.J., Alfaro E.J., Moitinho A., Franco J. <Astron. J. 116, 1801 (1998)> =1998AJ....116.1801D
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Photometry, UBV Keywords: open clusters and associations: individual (IC 4996) - stars: pre-main-sequence Abstract: The results of a UBV CCD photometric study of the cluster IC 4996 are presented. We obtain new values for the cluster parameters: E(B-V)=0.71±0.08, V0-MV=11.9±0.1, and age=(7.5±3)x106yr. The combined evidence from the photometric diagrams suggests the presence of a number of premain-sequence (PMS) cluster members with spectral types ∼A0 to F5. The interpretation of these objects as PMS candidates is further supported by independent results from CCD uvbyHβ observations. If confirmed, these stars would bridge the existing gap in the sample of PMS stars, between the coolest Herbig AeBe stars (HAeBe), and the hottest T Tauri stars. These PMS candidates are located some 0.5 and 1 mag above the main sequence in the V-(B-V) diagram, around the location of spectral types AF. This feature, together with their locations in the (U-B)-(B-V) diagram and the interpretation that they are PMS members, suggest an additional reddening law with a slope α=E(U-B)/E(B-V)∼0.55, probably caused by circumstellar material. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 20 16 30 +37 38.0 IC 4996 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 42 610 Photometry of Hoag et al. (1961PUSNO..17..343H, H61) stars and member stars
See also: http://obswww.unige.ch/webda/ : BDA database Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq Sequential number 4 A1 --- n_Seq [p*] Note on stars (1) 6- 8 I3 --- BDA ? BDA number (Mermilliod, 1995, http://obswww.unige.ch/webda/ 10- 16 F7.2 pix Xpos X position (2) 18- 24 F7.2 pix Ypos Y position (2) 26- 30 F5.2 mag Vmag V magnitude 32- 36 F5.2 mag B-V B-V colour index 38- 42 F5.2 mag U-B ? U-B colour index
Note (1): *: stars with H61 (Hoag et al, 1961PUSNO..17..349H) values p: suggested PMS members Note (2): 1 pix = 0.33". Y increasing from north to south, X increasing from west to east.
History: From AJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 09-Mar-1999
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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