Abstract
We present models of the late stages of stellar evolution intended to explain the "UV upturn" phenomenon in elliptical galaxies. Such models are sensitive to values of a number of poorly constrained physical parameters, including metallicity, age, stellar mass loss, helium enrichment, and the distribution of stars on the zero-age horizontal branch (HB). We explore the sensitivity of the results to values of these parameters and reach the following conclusions. Old, metal-rich galaxies, such as giant ellipticals, naturally develop a UV upturn within a reasonable timescale - less than a Hubble time - without the presence of young stars. The most likely stars to dominate the UV flux of such populations are low-mass, core helium-burning (HB and evolved HB) stars. Metal-poor populations produce a higher ratio of UV-to-V flux, owing to opacity effects, but only metal-rich stars develop a UV upturn, in which the flux increases toward shorter UV wavelengths.
| Original language | English |
|---|---|
| Pages (from-to) | 201-229 |
| Number of pages | 29 |
| Journal | Astrophysical Journal |
| Volume | 486 |
| Issue number | 1 PART I |
| DOIs | |
| Publication status | Published - 1997 Jan 1 |
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All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
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On the origin of the UV upturn in elliptical galaxies. I. Sensitivity of UV population synthesis to various input parameters. / Sukyoung, Y. I.; Demarque, Pierre; Oemler, Augustus.
In: Astrophysical Journal, Vol. 486, No. 1 PART I, 01.01.1997, p. 201-229.Research output: Contribution to journal › Article
TY - JOUR
T1 - On the origin of the UV upturn in elliptical galaxies. I. Sensitivity of UV population synthesis to various input parameters
AU - Sukyoung, Y. I.
AU - Demarque, Pierre
AU - Oemler, Augustus
PY - 1997/1/1
Y1 - 1997/1/1
N2 - We present models of the late stages of stellar evolution intended to explain the "UV upturn" phenomenon in elliptical galaxies. Such models are sensitive to values of a number of poorly constrained physical parameters, including metallicity, age, stellar mass loss, helium enrichment, and the distribution of stars on the zero-age horizontal branch (HB). We explore the sensitivity of the results to values of these parameters and reach the following conclusions. Old, metal-rich galaxies, such as giant ellipticals, naturally develop a UV upturn within a reasonable timescale - less than a Hubble time - without the presence of young stars. The most likely stars to dominate the UV flux of such populations are low-mass, core helium-burning (HB and evolved HB) stars. Metal-poor populations produce a higher ratio of UV-to-V flux, owing to opacity effects, but only metal-rich stars develop a UV upturn, in which the flux increases toward shorter UV wavelengths.
AB - We present models of the late stages of stellar evolution intended to explain the "UV upturn" phenomenon in elliptical galaxies. Such models are sensitive to values of a number of poorly constrained physical parameters, including metallicity, age, stellar mass loss, helium enrichment, and the distribution of stars on the zero-age horizontal branch (HB). We explore the sensitivity of the results to values of these parameters and reach the following conclusions. Old, metal-rich galaxies, such as giant ellipticals, naturally develop a UV upturn within a reasonable timescale - less than a Hubble time - without the presence of young stars. The most likely stars to dominate the UV flux of such populations are low-mass, core helium-burning (HB and evolved HB) stars. Metal-poor populations produce a higher ratio of UV-to-V flux, owing to opacity effects, but only metal-rich stars develop a UV upturn, in which the flux increases toward shorter UV wavelengths.
UR - http://www.scopus.com/inward/record.url?scp=21744448636&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=21744448636&partnerID=8YFLogxK
U2 - 10.1086/304498
DO - 10.1086/304498
M3 - Article
AN - SCOPUS:21744448636
VL - 486
SP - 201
EP - 229
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1 PART I
ER -