X iv : a st ro - p h / 97 04 10 4 v 1 1 1 A pr 1 99 7 H II Region Abundances in the Polar Ring of NGC 2685 1 Paul

نویسندگان

  • Paul B. Eskridge
  • Richard W. Pogge
چکیده

We have obtained optical spectrophotometry of 11 H II regions in the polar ring of NGC 2685 (the Helix galaxy), and have used these data to study the physical characteristics of the polar-ring H II regions. The H II regions have normal spectra with no suggestion of unusual density, temperature, extinction, or composition. Semi-empirical calculations yield high oxygen abundance estimates (0.8–1.1 Z⊙) in all H II regions. This, along with the observed (B−V ) color, Hα equivalent width, and molecular gas properties argue against the current picture in which polar rings form from tidally captured dwarf irregular galaxies, and suggests instead that the rings are long-lived, self-gravitating structures as predicted by some dynamical models. This would allow the time required for multiple generations of star formation, and for the retention of the resulting enriched ejecta for inclusion in further generations of star formation. Subject headings: galaxies: abundances — galaxies: individual (NGC 2685) — galaxies: interactions — ISM: H II regions This paper is partially based on observations obtained with the Multiple Mirror Telescope, a joint facility of the Smithsonian Institution and the University of Arizona. [email protected] [email protected]

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

A pr 1 99 7 The Nature of Compact Galaxies in the Hubble Deep Field — II : Spectroscopic Properties and Implications for the Evolution of the Star Formation Rate Density of the Universe

X iv :a st ro -p h/ 97 04 00 1v 1 1 A pr 1 99 7 The Nature of Compact Galaxies in the Hubble Deep Field — II: Spectroscopic Properties and Implications for the Evolution of the Star Formation Rate Density of the Universe. 1,2,3 Rafael Guzmán, Jesús Gallego, David C. Koo, Andrew C. Phillips, James D. Lowenthal, S. M. Faber, Garth D. Illingworth & Nicole P. Vogt University of California Observato...

متن کامل

ar X iv : a st ro - p h / 98 05 04 7 v 1 6 M ay 1 99 8 The energy distribution of β CrB for the specific stellar abundances

The comparison of the observed and computed energy distributions of β CrB has shown that a model with the specific chemical composition of the star can account for the visual enery distribution, while it is still unable to reproduce ultraviolet observations shortward of 1700Å. Furthermore, the predicted absorption of strong Fe ii and Mg ii UV lines is much larger than the observed one.

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 1997