J/AJ/121/318 BV photometry in NGC 5986 (Alves+, 2001)
CCD photometry of the globular cluster NGC 5986 and its post-asymptotic giant
branch and RR Lyrae stars.
Alves D.R., Bond H.E., Onken C.
<Astron. J. 121, 318 (2001)>
=2001AJ....121..318A 2001AJ....121..318A
ADC_Keywords: Clusters, globular ; Photometry, CCD ; Photometry, UBV
Keywords: color-magnitude diagrams - globular clusters: individual (NGC 5986) -
RR Lyrae variable - stars: AGB and post-AGB
Abstract:
We have obtained new CCD BV photometry of the little-studied southern
Galactic globular cluster NGC 5986, including light curves of five of
its RR Lyrae variables. The cluster's red giant branch bump is
detected for the first time, at V=16.47 ±0.03. We derive a reddening
and true distance modulus of E(B-V)=0.29±0.02 and
(m-M)0=15.15±0.10, respectively. The cluster's color-magnitude
diagram reveals a mostly blue horizontal branch, like that of M13 or
M2, and quite unlike M3; yet all of these clusters have nearly
identical metallicities ([Fe/H]CG97=-1.35). We show that the RR
Lyrae variables in NGC 5986 are about 0.2mag brighter on average than
those in M3, an important exception to the often-employed, universal
MV(RR)-[Fe/H] relation. Finally, we note that NGC 5986 contains two
luminous stars with spectral types A-F, which are likely to be
post-asymptotic giant branch (PAGB) objects. The V-band luminosity
function of such yellow PAGB stars is a promising standard candle. We
suggest that the luminosity function is sharply peaked at
MV(PAGB)=-3.28±0.07.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 55 6381 Calibrated BV photometry of NGC 5986 and
surrounding field
table2.dat 56 91 Time Series BV Photometry of Variable Stars
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See also:
V/97 : Updated 3rd Cat Variable Stars in Globular Clusters (Clement+ 1997)
J/A+AS/144/5 : Nearby globular clusters photometric catalog (Rosenberg+, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Stellar ID number
6- 13 F8.3 pix Xpix X pixel position (1)
15- 22 F8.3 pix Ypix Y pixel position (1)
24- 29 F6.3 mag Bmag B-band magnitude
31- 35 F5.3 mag e_Bmag Uncertainty in Bmag
37- 42 F6.3 mag Vmag V-band magnitude
44- 48 F5.3 mag e_Vmag Uncertainty in Vmag
50- 55 A6 --- Comm Comment on ID (2)
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Note (1): Pixel coordinates from 1998 data; the plate scale is 0.396"/pixel.
The center of the cluster is at approximately X=1025, Y=1025.
Note (2): Comments:
Star F = Foreground F dwarf;
PAGB-1 = The PAGB candidate denoted "BW" in Bond (2001, in prep.);
PAGB-2 = The PAGB candidate denoted "BE" in Bond (2001, in prep.);
V# = Known variable star designations.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Name Variable star identification (VNN)
5- 10 F6.3 mag Vmag V-band magnitude
12- 16 F5.3 mag e_Vmag Uncertainty in Vmag
18- 28 F11.3 d JD-Vmag Julian date of Vmag observation
30- 35 F6.3 mag Bmag B-band magnitude
37- 41 F5.3 mag e_Bmag Uncertainty in Bmag
43- 53 F11.3 d JD-Bmag Julian date of Bmag observation
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Table 3: Summary of light-curve characteristics
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ID P (days) AB AV (B-V)min Type
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V1 0.724704 1.20 0.95 17.29 16.60 0.75 RRab
V2 0.636044 1.60 1.05 17.12 16.37 1.00 RRab
V4 ≳20. 0.3 0.2 13.26 15.01 Semiregular
V6 0.627247 1.60 1.15 17.23 16.46 0.80 RRab
V9 0.554631 2.00 1.40 17.54 16.72 0.90 RRab
V10 0.2 0.1 16.66 15.29
V11 0.608155 1.50 1.20 17.22 16.47 0.80 RRab
V12 0.348834 0.70 0.50 15.15 14.66 Foreground RRc
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 26-Jul-2002