J/AJ/111/1596 BV photometry in Fornax globulars (Smith+ 1996)
Fornax globular clusters 1 and 5: A confirmed extragalactic second parameter
Pair
Smith E.O., Neill J.D., Mighell K.J., Rich M.
<Astron. J. 111, 1596 (1996)>
=1996AJ....111.1596S 1996AJ....111.1596S
ADC_Keywords: Clusters, globular ; Photometry
Abstract:
We report new color-magnitude diagrams for Fornax globular clusters 1
and 5 where our data reaches V=24, below the horizontal branch.
Using the index B-R/(B+V+R), a measure of the horizontal branch color,
we find cluster 1 has a red (-0.50±0.10) and cluster 5 an
intermediate color (-0.09±0.12) horizontal branch confirming the
first extragalactic second parameter pair. The HB types are markedly
redder than the Galactic globular clusters at [Fe/H]=-2. In globular
cluster 1, we find 21 possible variable stars out of 41 horizontal
branch stars. Cluster 1 has an anomalously low ratio of horizontal
branch to red giant stars, which formally gives a helium abundance of
0.16<Y<0.22, depending on the assumptions used. For both clusters
1 and 5, and for the red horizontal branch in the field adjacent to
cluster 5, V_HB = 21.25 ± 0.05. We give calibrated surface
brightness profiles and measure new core and tidal radii for cluster 1
of 17.6" and 104" and for cluster 5 of <2" and 91", respectively.
Objects:
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RA (2000) DE Designation(s)
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02 37 02 -34 11.0 Fornax cluster 1 = C 0235-344
02 42 21 -34 06.2 Fornax cluster 5 = C 0240-343
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 55 182 Fornax cluster 1 photometry
table4.dat 55 253 Fornax cluster 5 photometry
table.tex 66 489 AASTeX version of table3.dat and table4.dat
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Byte-by-byte Description of file: table3.dat table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Identification number
5- 11 F7.1 pix Xpos X coordinate
13- 19 F7.1 pix Ypos Y coordinate
21- 26 F6.2 mag Vmag V magnitude
28- 31 F4.2 mag e_Vmag Error in Vmag
33- 38 F6.2 mag Bmag B magnitude
40- 43 F4.2 mag e_Bmag Error in Bmag
45- 50 F6.2 mag B-V B-V color
52- 55 F4.2 mag e_B-V Error in B-V
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Origin: AAS CD-ROM series, Volume 6, 1996 Lee Brotzman [ADS] 03-May-1996
(End) [CDS] 05-Sep-1996