High-resolution STIS/Hubble Space Telescope and HIRES/Keck spectra of three weak Mg II absorbers toward PG 1634+706

Jane C. Charlton, Jie Ding, Stephanie G. Zonak, Christopher W. Churchill, Nicholas A. Bond, Jane R. Rigby

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


High-resolution optical (HIRES/Keck) and UV (STIS/Hubble Space Telescope) spectra, covering a large range of chemical transitions, are analyzed for three single-cloud weak Mg II absorption systems along the line of sight toward the quasar PG 1634+706. Weak Mg II absorption lines in quasar spectra trace metal-enriched environments that are rarely closely associated with the most luminous galaxies (>0.05L*). The two weak Mg II systems at z = 0.81 and 0.90 are constrained to have at least solar metallicity, while the metallicity of the z = 0.65 system is not as well constrained, but is consistent with more than 1/10 solar. These weak Mg II clouds are likely to be local pockets of high metallicity in a lower metallicity environment. All three systems have two phases of gas, a higher density region that produces narrower absorption lines for low-ionization transitions, such as Mg II, and a lower density region that produces broader absorption lines for high-ionization transitions, such as C IV. The C IV profile for one system (at z = 0.81) can be fitted with a single broad component (b ∼ 10 km s-1), but those for the other two systems require one or two additional offset high-ionization clouds. Two possible physical pictures for the phase structure are discussed: one with a low-ionization, denser phase embedded in a lower density surrounding medium and the other with the denser clumps surrounding more highly ionized gas.

Original languageEnglish (US)
Pages (from-to)111-125
Number of pages15
JournalAstrophysical Journal
Issue number1 I
StatePublished - May 20 2003

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'High-resolution STIS/Hubble Space Telescope and HIRES/Keck spectra of three weak Mg II absorbers toward PG 1634+706'. Together they form a unique fingerprint.

Cite this