GCN Circular 7192
Subject
Transient in NGC2770 / SN2008D: Metallicity of nearby HII regions
Date
2008-01-17T15:27:09Z (17 years ago)
From
Edo Berger at Princton U <eberger@astro.princeton.edu>
E. Berger and A. M. Soderberg (Princeton) report on behalf of a larger
collaboration:
"We used the ARC 3.5-m telescope at Apache Point Observatory to obtain
spectroscopic observations of the X-ray transient in NGC2770 (GCN 7159).
We obtained 4x1200 sec exposures with the DIS red+blue cameras providing a
wavelength range of 3600-9000A. The spectra therefore cover a wide range
of nebular emission lines relevant for metallicity measurements (i.e.
[OII], H-beta, [OIII], H-alpha, [NII], and [SII]). Following the
prescriptions of Kewley & Dopita (2002) we use several indicators (e.g.
[NII]/[OII], R23) to measure the metallicity and ionization parameter of
bright HII regions within +/-8 arcsec (about 1 kpc) of the X-ray transient
position. We find metallicities of 12+log(O/H)=8.9+/-0.2, or about
0.6-1.6 times the solar metallicity. The error bar includes both the
spread in metallicity and the systematic uncertainty between the various
indicators. This value is higher, and more robust, than the estimate in
GCN 7189 which relied on an assumed metallicity gradient."