2016A&A...592A..47N


Query : 2016A&A...592A..47N

2016A&A...592A..47N - Astronomy and Astrophysics, volume 592A, 47-47 (2016/8-1)

Constraining the escape fraction of ionizing photons from HII regions within NGC 300: A concept paper.

NIEDERHOFER F., HILKER M., BASTIAN N. and ERCOLANO B.

Abstract (from CDS):

Using broadband photometry from the Hubble Space Telescope in combination with Very Large Telescope narrowband Hα observations of the nearby spiral galaxy NGC 300, we explore a method for estimating the escape fractions of hydrogen-ionizing photons from HII regions within this galaxy. Our goal in this concept study is to evaluate the spectral types of the most massive stars using the broadband data and estimating their ionizing photon output with the help of stellar atmosphere models. A comparison with the Hα flux that gives the amount of ionized gas in the HII region provides a measure of the escape fraction of ionizing photons from that region. We performed some tests with a number of synthetic young clusters with varying parameters to assess the reliability of the method. However, we found that the derived stellar spectral types and consequently the expected ionizing photon luminosity of a region is highly uncertain. The tests also show that on one hand we tended to overestimate the integrated photon output of a region for young ages and low numbers of stars, and on the other hand we mostly underestimated the combined ionizing luminosity for a large stellar number and older cluster ages. We conclude that the proposed method of using stellar broadband photometry to infer the leakage of ionizing photons from HII regions is highly uncertain and dominated by the errors of the resulting stellar spectral types. Therefore this method is not suitable. Stellar spectra are needed to reliably determine the stellar types and escape fractions. Studies to this end have been carried out for the Magellanic Clouds.

Abstract Copyright: © ESO, 2016

Journal keyword(s): stars: massive - H II regions - galaxies: individual: NGC 300 - galaxies: ISM

Nomenclature: Table 2: [NHB2016] NN (Nos 1-20).

Simbad objects: 33

goto Full paper

goto View the references in ADS

Number of rows : 33
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10361 1
2 [DCL88] 15 HII 00 54 24.87 -37 39 47.1           ~ 3 0
3 [DCL88] 17 HII 00 54 25.63 -37 39 09.8           ~ 3 0
4 [DCL88] 20 HII 00 54 27.26 -37 40 01.6           ~ 2 0
5 [DCL88] 25 HII 00 54 28.77 -37 38 36.6           ~ 6 0
6 [DCL88] 26 HII 00 54 29.45 -37 37 23.3           ~ 2 0
7 [NHB2016] 6 HII 00 54 31.66 -37 37 51.0           ~ 1 0
8 [BL97] N300-H4 HII 00 54 31.71 -37 37 58.4           ~ 8 0
9 [DCL88] 31 HII 00 54 32.07 -37 37 43.7           ~ 4 0
10 [BL97] N300-H5 HII 00 54 32.18 -37 38 34.6           ~ 7 0
11 [NHB2016] 7 HII 00 54 32.42 -37 38 41.1           ~ 1 0
12 [DCL88] 34 HII 00 54 32.7 -37 38 42           ~ 4 0
13 [NHB2016] 8 HII 00 54 35.25 -37 39 42.6           ~ 1 0
14 [BL97] N300-H8 HII 00 54 35.33 -37 39 35.7           ~ 10 0
15 [DCL88] 38 HII 00 54 36.06 -37 39 50.6           ~ 4 0
16 [DCL88] 48 HII 00 54 41.84 -37 38 36.4           ~ 4 0
17 [DCL88] 49 HII 00 54 42.15 -37 39 02.8           ~ 4 0
18 [NHB2016] 12 HII 00 54 42.19 -37 39 02.7           ~ 1 0
19 [DCL88] 50 HII 00 54 42.34 -37 38 53.6           ~ 6 0
20 [DCL88] 56 HII 00 54 44.24 -37 40 26.3           ~ 11 0
21 [NHB2016] 14 HII 00 54 45.19 -37 41 49.0           ~ 1 0
22 [DCL88] 61 HII 00 54 45.35 -37 38 47.0           ~ 12 0
23 [DCL88] 74 HII 00 54 49.88 -37 41 12.5           ~ 4 0
24 [NHB2016] 17 HII 00 54 50.70 -37 40 24.1           ~ 1 0
25 [DCL88] 76B HII 00 54 50.74 -37 40 15.2           ~ 8 0
26 [DCL88] 81 HII 00 54 51.33 -37 41 45.9           ~ 6 0
27 [DCL88] 84 SNR 00 54 51.73 -37 39 38.6 17.168 19.517 19.073     ~ 18 0
28 [DCL88] 85 HII 00 54 52.05 -37 41 40.6           ~ 6 0
29 NGC 300 GiG 00 54 53.4465638304 -37 41 03.168402396 8.83 8.69 8.13 7.46   ~ 1417 2
30 NAME Scl Group GrG 01 00 06 -33 44.2           ~ 493 0
31 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6408 1
32 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1882 1
33 Feige 110 HS* 23 19 58.3996844256 -05 09 56.171142864 10.360 11.45 11.50 11.970 12.145 sdO8VIIIHe5 602 1

To bookmark this query, right click on this link: simbad:objects in 2016A&A...592A..47N and select 'bookmark this link' or equivalent in the popup menu


2022.09.24-18:12:02

© Université de Strasbourg/CNRS

    • Contact