J/AN/322/73 BVIc photometry in NGC 2976 (Notni+, 2001)
Photometry of young starlike objects in the dwarf galaxy NGC 2976 -
age and metallicity.
Notni P., Karachentsev I.D., Makarova L.N.
<Astron. Nachrichten, 322, 73-86 (2001)>
=2001AN....322...73N 2001AN....322...73N
ADC_Keywords: Galaxies, photometry ; Stars, bright ; Photometry, CCD
Keywords: galaxies: dwarf - galaxies: individual (NGC 2976) -
galaxies: stellar photometry - galaxies: stellar content
Abstract:
We present BVIc photometry of the brightest stars and compact star
clusters in NGC 2976, a dwarf galaxy in the interacting M81/M82 group.
Deep CCD images of the galaxy were obtained with the 6m-Telescope of
the Special Astrophysical Observatory (Russia) at arcsec resolution.
About 290 young stars and concentrated young clusters were measured.
Supplementaxy data in the ultraviolet are taken from the literature.
The extinction to the measured objects is comparatively low,
E(B-V)∼0.15-0.20mag. We estimate the ages of youngest resolved stars
and concentrated star clusters to be ∼5x106years. This population
is concentrated in a broad stripe facing M81. In the central disk the
population is a bit older, about 8x106years, this may be a hint to
an outward spreading star formation process. The metallicity of the
disk population is estimated as solar (z∼0.02) from a fitting to
Padova theoretical stellar isochrones.
Objects:
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RA (2000) DE Designation(s)
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09 47 15.5 +67 54 59 NGC 2976 = MCG+11-12-025
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 67 288 BVIc photometry of bright starlike objects in
NGC 2976
table3.dat 67 39 BVIc photometry, mean values of very tight
(<0.8") multiple objects
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Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 4 I04 --- [NKM2001] Identification number (1)
5 A1 --- m_[NKM2001] [abc] Multiplicity index (1)
7- 9 I3 --- [BNM92] ? Blue Knots identification number,
[BNM92] BKNN in Simbad (2)
11- 16 F6.2 pix Xpos X position (3)
18- 23 F6.2 pix Ypos Y position (3)
25- 30 F6.2 mag Vmag ?=100.0 Johnson V magnitude (4)
32- 37 F6.2 mag B-V ?=100.0 Johnson B-V colour index (4)
39- 44 F6.2 mag V-Ic ?=100.0 Johnson-Cousins V-I colour index (4)
46- 51 F6.3 mag (U-B)p ? Photographic (U-B) colour index
53- 55 I3 --- q_Bmag ?=999 Quality indicator on B frame (7)
57- 59 I3 --- q_Vmag ?=999 Quality indicator on V frame (7)
61- 63 I3 --- q_Imag ?=999 Quality indicator on I frame (7)
65 I1 --- T [1/3]? Number of objects with the same
sequential number (5)
67 I1 --- Ext [0/4] Position label (6)
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Note (1): Very tight neighbours (distance<0.8") are given the same number.
They are differenciated with a letter, a, b, c.
Note (2): Identification number of Blue Knots from the photographic
measures of Bronkalle et al., 1992AN....313....1B 1992AN....313....1B (their Table 2).
If more than one object measured here may be contained in the knot,
the identification is given for all of them. The nearest one is the
one for which (U-B)p is given.
Note (3): Coordinates in pixels, 1pixel=0.20arcsec.
The x-direction points towards PA=242.2° (south-west), the major
axis of NGC 2976 (PA=322°) is inclined about 10 degrees towards
west from the y-axis.
Note (4): '100.0' marks objects too faint in V (and B) to be measured
Note (5): Flag T as follows:
1 = normal single object
2 = object has 1 close neighbour
3 = object has 2 close neighbours
Note (6): Position label as follows:
0 = red region
1 = bluest region
2 = red region
3 = moderately blue region
4 = moderately blue region
Note (7): the quality gives an estimate of the error in units of
0.01mag/pixel step in radius. Reliable measurements have their
quality less than 15.
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History:
Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 25-Oct-2001