On the hardening of the ionizing radiation in HII regions across galactic discs through softness parameters

Details On the hardening of the ionizing radiation in HII regions across galactic discs through softness parameters On the hardening of the ionizing radiation in HII regions across galactic discs through softness parameters

2009-08-21

arxiv.org/abs/0908.3069v1

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

To appear as a letter in MNRAS. 5 pages, 4 figures and 2 tables

Scientific paper

We carry out a study of the hardness of the radiation of ionizing clusters in HII regions. Firstly, we explore the applicability of the softness parameter, originally defined in the optical for pairs of consecutive ionization stages of the same species. With the advent of the infrared space observatories, this definition has been extended to the mid-infrared. We show that the softness parameters, as determined both in the optical and the mid-infrared wavelengths, are sensitive to the effective temperature using a sample of data in both spectral regimes. This is confirmed by comparing the data with a grid of photoionization models, although no complete agreement has been found even for different stellar model atmospheres. Finally, we show that both softness parameters are consistent in the search for radial variations of the hardness of the ionizing radiation of HII regions in the discs of spiral galaxies. We find a range of trends, from galaxies showing pronounced gradients to those showing very flat ones. Although the detectability and slope of these gradients can be altered by the size and luminosity of the studied HII regions, it looks that their existence is related to the mass and type of the galaxies and, hence, to the roperties of the entire disc.

Affiliated with

Also associated with

No associations

Rating

On the hardening of the ionizing radiation in HII regions across galactic discs through softness parameters does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with On the hardening of the ionizing radiation in HII regions across galactic discs through softness parameters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the hardening of the ionizing radiation in HII regions across galactic discs through softness parameters will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-666433