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J/A+A/288/413 Massive stars in I Zw 36 (Deharveng+ 1994)
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The massive star content of the blue dwarf galaxy I Zw 36 from
Faint Object Camera observations.
Deharveng J.-M., Albrecht R., Barbieri C., Blades J.C., Boksenberg A.,
Crane P., Disney M.J., Jakobsen P., Kamperman T.M., King I.R.,
Macchetto F., Mackay C.D., Paresce F., Weigelt G., Baxter D.,
Greenfield P., Jedrzejewski R., Nota A., Sparks W.B.
<Astron. Astrophys. 288, 413 (1994)>
=1994A&A...288..413D (SIMBAD/NED BibCode)
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ADC_Keywords: Photometry, ultraviolet ; Populations, stellar
Mission_Name: HST
Keywords: stars: formation - stars: mass function - galaxies: stellar content -
ultraviolet: galaxies - galaxies: I Zw 36
Abstract:
We have observed the blue dwarf galaxy I Zw 36 with the f/96 relay of
the HST Faint Object Camera and have for the first time resolved
massive stars, using the broad band filters F175W, F342W, F430W and
F480LP. We have measured the fluxes of 143 of these objects and
studied their characteristics in color-magnitude diagrams. A few stars
may be red supergiants but their contribution to the integrated light
is less than 5% in the F430W filter. The F175W-F430W color of the
integrated stellar population is redder than expected from the current
burst of star formation, suggesting therefore the presence of an older
and unresolved underlying population. The ultraviolet measurements
combined with synthetic photometry calculations allow us to place the
massive stars in a bolometric magnitude vs. temperature diagram. In
this diagram, the stars are compared to evolutionary tracks for
different stellar masses. The current burst probably has an age less
than 12Myr. We infer an Initial Mass Function, with a power-law slope
in the range -1.7 to -2.6 for masses M>=20M_{sun}_. This is consistent
with most of the values reported for sites of star formation in the
Galaxy and the Magellanic Clouds and does not support the view of an
IMF flattening at low metallicity.
Objects:
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RA (2000) DE Designation(s)
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12 26 16.0 +48 29 31 ZW I 36 = Mrk 209
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 33 143 Photometry of stars
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Identification number
5- 9 F5.1 pix Xpos X position (1)
11- 15 F5.1 pix Ypos Y position (1)
17- 21 F5.2 mag m175 ? Magnitude through the F175W filter
23- 27 F5.2 mag m342 ? Magnitude through the F342W filter
29- 33 F5.2 mag m430 Magnitude through the F430W filter
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Note (1): 1 pix = 0.022". The origin is the lower left corner of Fig.1 and
X-axis is the horizontal axis.
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History: Prepared via OCR at CDS.
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(End) James Marcout, Patricia Bauer [CDS] 28-Jan-1997