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Galactic bulge M giants. III - Near-infrared spectra and implications for the stellar content of E and S0 galaxies
Spectra at 0.6-0.9 micron of 320 K and M giants in six low-absorptionfields along the minor axis of the galactic bulge and of an additional60 late-type giants and dwarfs in the solar neighborhood were obtained.Indices of the strength of molecular absorption are combined withprevious infrared and optical photometry to estimate the mean metalabundance of the bulge M giants and to constrain the relativecontribution of late giants and dwarfs to the integrated light of E andS0 galaxies.
| Observations of high-redshift CA II absorption in QSO spectra
A spectroscopic search for Ca II H and K absorption in known QSOabsorption systems is reported, resulting in the detection of this ionin the QSO PKS 0454-22 at z(abs) = 0.4745. Fe II and Mg II absorptionlines in this system have been observed, and it is shown that gaseous CaII is severely underabundant with respect to both Fe II and Mg II. Ifthe observed fraction of Ca II is typical of QSO absorption systems itwould explain why this ion has not been readily seen and why two otherobserved objects, 1101-264 and the BL Lac PKS 0735 + 178, did not givepositive detections. The underabundance of Ca II with respect to Fe IIand Mg II is similar to that in interstellar clouds in the Galaxy,suggesting the selective condensation of elements on to grains.Alternatively, the lack of Ca II may be due to ionization equilibriumconditions, i.e., a lower ratio of the electron density to thephotoionization rate of Ca(+) in the absorbing region than typicallyfound in disk gas in the Galaxy.
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Osservazione e dati astrometrici
| Costellazione: | Vele |
| Ascensione retta: | 09h46m06.08s |
| Declinazione: | -55°47'37.2" |
| Magnitudine apparente: | 8.598 |
| Distanza: | 369.004 parsec |
| Moto proprio RA: | -12.4 |
| Moto proprio Dec: | 2.9 |
| B-T magnitude: | 10.006 |
| V-T magnitude: | 8.715 |
Cataloghi e designazioni:
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