| | |
| | |
Stat |
Members: 3643 Articles: 2'487'895 Articles rated: 2609
28 March 2024 |
|
| | | |
|
Article overview
| |
|
Andromeda IV: a new Local Volume very metal-poor galaxy | S.A.Pustilnik
; A.L.Tepliakova
; A.Y.Kniazev
; A.N.Burenkov
; Russia;
; SAAO
; South Africa
; | Date: |
27 Dec 2007 | Abstract: | And IV is a low-surface brightness (LSB) dwarf galaxy projecting close to
Messier 31. Ferguson et al. (2000, FGW), from the Hubble Space Telescope (HST)
study placed it at the distance of 6.1 Mpc. On the results of its several HII
regions spectroscopy they also estimated their oxygen abundance 12+log(O/H) of
~7.90 via the empirical calibration R_23 method. In this paper the results of
the spectroscopy of And IV two brightest HII regions with the SAO 6-m telescope
(BTA) are presented. In both of them the faint line [OIII]4363A was detected
that allowed us to determine their O/H by the classical T_e method. Their mean
12+log(O/H)=7.42+-0.10. The line intensities of these HII regions from FGW
paper, with addition of I([OIII]4363) roughly estimated from their plots for
the respective spectra were used to recalculate O/H via the classical T_e
method. The derived mean value of 12+log(O/H) for the same two HII-regions
appeared of 7.67+-0.14. Thus, the two independent values O/H are consistent
each with other within their uncertainties. Their weighted mean is of
12+log(O/H)=7.50+-0.10 (in the old scale). For And IV blue luminosity of
M_B=-12.6, the latter value of O/H fits much better to the ’standard’ relation
between O/H and L_B for dwarf irregular galaxies (DIGs). Also, the new value of
O/H is better consistent with the known unusually large value of M(HI)/L_B 13
for galaxy And IV. And IV appears to be a new representative of the extremely
metal-deficient gas-rich galaxies in the Local Volume. The very large range of
M(HI) for LSB galaxies with close metallicities and luminosities indicates that
the simple models of LSBG chemical evolution are too limited to predict such
striking diversity. | Source: | arXiv, 0712.4205 | Services: | Forum | Review | PDF | Favorites |
|
|
No review found.
Did you like this article?
Note: answers to reviews or questions about the article must be posted in the forum section.
Authors are not allowed to review their own article. They can use the forum section.
browser claudebot
|
| |
|
|
|
| News, job offers and information for researchers and scientists:
| |