HST Spectra of Stellar Populations: The Extinction Law and IMF in M 101

Rosa, M. R.; Benvenuti, P.

doi:10.1007/978-94-011-0794-5_100

Cited by 19 publications

(32 citation statements)

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“…Mas-Hesse & Kunth (1999) deduced an age of 2.9 Myr for NGC 5471, which is too young to explain the faint P Cygni profiles observed in the FUV diagnostic lines. Oxygen abundances ranging from 8.0 to 8.2 (0.2-0.3 Z ; Torres-Peimbert et al 1989;Rosa & Benvenuti 1994;Mas-Hesse & Kunth 1999;Bosch et al 2002) are found in the literature, which is in good agreement with FUV synthesis.…”

Section: Ngc 5471supporting

confidence: 84%

“…A good correspondence is also obtained with 0.4 Z models at 3:3 AE 0:2 Myr, still with < 2:35. A multiwavelength study from Rosa & Benvenuti (1994) suggests an age between 3.0 and 4.5 Myr, compatible with FUV line profiles. Luridiana & Peimbert (2001) deduced an age between 2.5 and 3.5 Myr based on EW( H ), also in general agreement with FUV line profiles.…”

Section: Ngc 5461mentioning

confidence: 60%

“…The other clusters are probably older and do not seem to contribute much to the FUV flux. Abundances ranging from 8.4 to 8.6 in 12 þ log ½O/ H are found in the literature (Torres-Peimbert et al 1989;Scowen et al1992;Rosa & Benvenuti 1994;Luridiana & Peimbert 2001). Their observations favor the FUV synthesis models at 0.4 Z .…”

Section: Ngc 5461mentioning

confidence: 71%

“…Using a standard IMF slope of 2.35, the calculated stellar mass is then (5 AE 1) ; 10 4 M . According to Rosa & Benvenuti (1994), the extinction from the Balmer decrement is 0.23, and using an extinction law especially designed for M101, they find a stellar mass of 1 ; 10 5 M . According to LavalSB, the FUV stellar population should produce an H flux of (5 AE 2) ; 10 À13 ergs s À1 cm À2 8 À1 , while H image data give 6.5 and 3:2 ; 10 À12 ergs s À1 cm À2 8 À1 (Bosch et al 2002;Kennicutt 1979, respectively).…”

Section: Ngc 5461mentioning

confidence: 99%

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Massive Stellar Content of Giant HiiRegions in M33 and M101

Pellerin

2006

Astron J

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Far-ultraviolet (900-1200 8) spectral synthesis of nine giant extragalactic H ii regions in M33 and M101 is performed to study their massive stellar content. Several parameters are quantified, predicted, and compared to the literature: age, stellar mass, initial mass function ( IMF) slope, number of O-type and Wolf-Rayet stars, and H and 5500 8 continuum fluxes. The results of this particular technique are consistent with other methods and observations. This work shows that a total stellar mass of a few 10 3 M is needed to populate the IMF bins well enough at high masses to obtain accurate results from the spectral synthesis technique in the far-ultraviolet. A flat IMF slope seems to characterize better the stellar line profiles of these objects, which is likely the first sign of a small number statistics effect on the IMF. Finally, the H ii region NGC 5461 is identified as a good candidate for hosting a second generation of stars, not yet seen at far-ultraviolet wavelengths.

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Section: Ngc 5471supporting

confidence: 84%

Section: Ngc 5461mentioning

confidence: 60%

Section: Ngc 5461mentioning

confidence: 71%

Section: Ngc 5461mentioning

confidence: 99%

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Massive Stellar Content of Giant HiiRegions in M33 and M101

Pellerin

2006

Astron J

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“…Bianchi et al (1996) derived an average extinction law for stars in M31 ; they found an average extinction law similar to that in the Galaxy, except possibly for a weaker 2175 bump. Rosa & Benvenuti A (1994) found a similar result based on FOS spectroscopy of OB associations in M101. The uncertainties in both of these results are still relatively large, however.…”

Section: Corrections For Interstellar Reddeningsupporting

confidence: 72%

Carbon in Spiral Galaxies fromHubble Space TelescopeSpectroscopy

Garnett

Shields

Peimbert³

et al. 1999

ApJ

156

256

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We present measurements of the gas-phase abundance ratio C/O in six H II regions in the spiral galaxies M101 and NGC 2403, based on ultraviolet spectroscopy using the Faint Object Spectrograph on the Hubble Space T elescope. The ratios of C to O increase systematically with O/H in both galaxies, from log C/O B [0.8 at log O/H \ [4.0 to log C/O B [0.1 at log O/H \ [3.4. C/N shows no correlation with O/H. The rate of increase of C/O is somewhat uncertain because of uncertainty as to the appropriate UV reddening law and uncertainty in the metallicity dependence on grain depletions. However, the trend of increasing C/O with O/H is clear, conÐrming and extending the trend in C/O indicated previously from observations of irregular galaxies. Our data indicate that the radial gradients in C/H across spiral galaxies are steeper than the gradients in O/H. Comparing the data to chemicalevolution models for spiral galaxies shows that models in which the massive star yields do not vary with metallicity predict radial C/O gradients that are much Ñatter than the observed gradients. The most likely hypothesis at present is that stellar winds in massive stars have an important e †ect on the yields and thus on the evolution of carbon and oxygen abundances. C-to-O and N-to-O abundance ratios in the outer disks of spirals determined to date are very similar to those in dwarf irregular galaxies. This implies that the outer disks of spirals have average stellar-population ages much younger than those of the inner disks.

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Chemical abundances of the H II regions NGC 5461 and NGC 5471 in M 101, Derived from echelle spectrophotometry

Luridiana

Esteban

Peimbert

et al. 2003

Symp. - Int. Astron. Union

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We present high resolution spectroscopic data of the two giant extragalactic H ii regions NGC 5461 and NGC 5471 in M 101. We calculate the physical conditions in the two nebulae with a large number of diagnostics, and determine their chemical abundances by applying ionization correction factors (icfs) to the observed ionic abundances. The comparison of the icfs based on photo-ionization models (Luridiana & Peimbert 2001; Luridiana et al. 1999) to those computed following the prescriptions by Mathis & Rosa (1991) shows large discrepancies for several elements, including nitrogen, neon and chlorine.

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HST Spectra of Stellar Populations: The Extinction Law and IMF in M 101

Cited by 19 publications

References 0 publications

Massive Stellar Content of Giant HiiRegions in M33 and M101

Massive Stellar Content of Giant HiiRegions in M33 and M101

Carbon in Spiral Galaxies fromHubble Space TelescopeSpectroscopy

Chemical abundances of the H II regions NGC 5461 and NGC 5471 in M 101, Derived from echelle spectrophotometry

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