J/AJ/127/1982 HST UBVI photometry of NGC 3081 inner regions (Buta+, 2004)
A Hubble space telescope study of star formation in the inner resonance ring
of NGC 3081.
Buta R.J., Byrd G.G., Freeman T.
<Astron. J., 127, 1982-2001 (2004)>
=2004AJ....127.1982B 2004AJ....127.1982B
ADC_Keywords: Galaxies, photometry ; Photometry, UBVRI ; Photometry, Cousins
Keywords: galaxies: individual (NGC 3081) - galaxies: photometry -
galaxies: spiral - galaxies: structure
Abstract:
We present Hubble Space Telescope Wide Field Planetary Camera 2 images
of the inner regions of NGC 3081, an absolute magnitude MB=-20.0
early-type barred spiral having four well-defined resonance rings: a
nuclear ring, an inner ring, an outer R1 ring, and an outer R'2
pseudoring. Here we focus on a photometric study of the inner ring, a
feature likely associated with an inner 4:1 resonance near the ends of
the bar. The ring is notable for its high contrast and sharp
definition, which is due to a significant degree of active star
formation. The ring is also notable for its significant intrinsic
elongation and parallel alignment with the bar.
Description:
The Hubble Space Telescope (HST) observations of NGC 3081 were secured
on 2000 June 25 with the Wide Field Planetary Camera 2 (WFPC2). The
center of the galaxy was placed near the overlap section between WFPC2
sections WF3 and WF4. Five broadband filters were used to observe the
galaxy: F255W, F336W, F439W, F555W, and F814W. The latter four filters
are intended to approximate Johnson U, B, V, and Cousins I photometric
systems, respectively, while F255W is a mid-ultraviolet filter.
Objects:
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RA (2000) DE Designation(s)
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09 59 29.5 -22 49 35 NGC 3081 = IC 2529
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 72 58 Photometry of ring sources brighter than V=23.6
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- [BBF2004] Sequential number
4- 9 F6.2 arcsec DXpos Offset along X axis from nucleus (1)
11- 16 F6.2 arcsec DYpos Offset along Y axis from nucleus (1)
18- 22 F5.2 mag V0mag Dereddened V magnitude (2)
24- 27 F4.2 mag e_V0mag rms uncertainty on V0mag
29- 33 F5.2 mag (U-B)0 Dereddened U-B colour index (2)
35- 38 F4.2 mag e_(U-B)0 rms uncertainty on (U-B)0
40- 44 F5.2 mag (B-V)0 Dereddened B-V colour index (2)
46- 49 F4.2 mag e_(B-V)0 rms uncertainty on (B-V)0
51- 55 F5.2 mag (V-Ic)0 Dereddened Cousins V-I colour index (2)
57- 60 F4.2 mag e_(V-Ic)0 rms uncertainty on (V-Ic)0
62- 67 F6.2 mag VMAG Absolute V magnitude, if the object is part
of NGC 3081
69- 72 F4.2 mag DV(0.5-3) Concentration parameter (3)
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Note (1): DXpos is westward while positive, DYpos is northward
Note (2): Magnitudes and colors corrected only for Galactic extinction.
Note (3): Concentration parameter, defined as the difference in V magnitude
between a 0.5 pixel radius and a 3 pixel radius aperture. Some of
the objects with ΔV<1.78 are likely to be foreground stars.
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History:
From electronic version of the journal
(End) James Marcout, Patricia Vannier [CDS] 02-Jul-2004