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 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:
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RA (2000) DE Designation(s)
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20 16 30 +37 38.0 IC 4996
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 42 610 Photometry of Hoag et al. (1961PUSNO..17..343H 1961PUSNO..17..343H,
H61) stars and member stars
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See also:
http://obswww.unige.ch/webda/ : BDA database
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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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
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Note (1):
*: stars with H61 (Hoag et al, 1961PUSNO..17..349H 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.
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History: From AJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 09-Mar-1999