Photometric studies of very metal-deficient blue compact dwarf galaxies: the exponential ionized gas halo of IZw18

Details Photometric studies of very metal-deficient blue compact dwarf galaxies: the exponential ionized gas halo of IZw18 Photometric studies of very metal-deficient blue compact dwarf galaxies: the exponential ionized gas halo of IZw18

Apr 2003

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003ap%26ss.284..619p&link_type=abstract

Astrophysics and Space Science, v. 284, Issue 2, p. 619-622 (2003).

Astronomy and Astrophysics

Astrophysics

3

Galaxies: Dwarf, Galaxies: Compact, Galaxies: Structure

Scientific paper

Using HST and ground-based optical and NIR imaging data, we investigate whether the blue compact dwarf (BCD) galaxy I Zw 18 possesses an extended low-surface brightness (LSB) old stellar population underlying its star-forming (SF) regions. We show that the exponential intensity decrease observed in the filamentary LSB envelope of the BCD out to 18″ (1.3 kpc at the adopted distance of 15 Mpc) is not due to an evolved stellar disc, but rather due to extended ionized gas emission. Broad-band images reveal, after subtraction of nebular line emission, a compact stellar LSB component extending slightly beyond the SF regions. This stellar host, being blue over a radius range of 5 exponential scale lengths and showing little colour contrast to the SF component, differs strikingly from the red LSB host of standard BCDs. This fact, in connection with the blue colours of component I Zw 18 C (see discussion in Papaderos et al. 2002), suggests that most of the stellar mass in I Zw 18 has formed within the last 0.5 Gyr. Furthermore, we show that the exponential intensity fall-off in the filamentary ionized envelope of I Zw 18 is not particular to this system but a common property of the ionized halo of many SF dwarf galaxies on galactocentric distances of several kpc. In the absence of an appreciable underlying stellar background, extended ionized gas emission dominates in the periphery of I Zw 18, superficially resembling an exponential stellar disc on optical surface brightness profiles. The case of I Zw 18 suggests caution in the search of more distant young galaxy candidates. Intense SF activity in the early phase of dwarf galaxy formation may result in an extended ionized gas halo which can be mistaken for an evolved stellar disc by studying only its exponential surface brightness profile.

Affiliated with

Also associated with

No associations

Rating

Photometric studies of very metal-deficient blue compact dwarf galaxies: the exponential ionized gas halo of IZw18 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 Photometric studies of very metal-deficient blue compact dwarf galaxies: the exponential ionized gas halo of IZw18, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photometric studies of very metal-deficient blue compact dwarf galaxies: the exponential ionized gas halo of IZw18 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-919640