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Near-Infrared Spectral Properties of Metal-Poor Red Supergiants

Valentin D. Ivanov (ESO) Collaborators: Marcia J. Rieke, A. Alonso-Herrero, Danielle Alloin. Near-Infrared Spectral Properties of Metal-Poor Red Supergiants.

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Near-Infrared Spectral Properties of Metal-Poor Red Supergiants

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  1. Valentin D. Ivanov (ESO) Collaborators: Marcia J. Rieke, A. Alonso-Herrero, Danielle Alloin Near-Infrared Spectral Properties of Metal-Poor Red Supergiants

  2. - improved metallicity coverage for red supergiants for population synthesis models of metal-poor galaxies undergoing active star formation - higher resolution than the typically used 2000-3000 in order to work in-between the sky emission lines, for example searching for high redshift emitters in the near infrared - stellar abundance and abundance ratio analysis - templates are needed for kinematic mass estimates of the recently discovered massive star clusters; such estimates would be based on the CO band head (i.e. Mengel et al. 2002) Why the world needs yet another near-infrared spectral atlas?

  3. Summary from Ivanov et al. (2004, accepted to ApJS) Currently Available IR Spectral Atlases From Ivanov et al. (2004, ApJS. 151, 387)

  4. - goal: equidistant Teff coverage at fixed abundance [Fe/H]~ -0.65 - Observed stars: -- sequence of: K2-K5-M0-M1-M6 SMC RSGs -- Milky Way stars: HD8498 – K5 III HD207585 – K2 II Program stars - Sample Selection

  5. MBR – Meliani et al. (1995) OSK - Oestreicher and Schmidt-Kaler (1998) Program stars – Sample Selection Red line – observed SMC stars

  6. - one night with ISAAC @ VLT: Aug 25/26, 2002 - strategy: 1 or 2 AB cycles = nodding along the slit; always a nearby star of similar brightness was put in the slit - set up: slit 0.6”; typically 1x120 sec in H-band and 2x120 sec in K-band; R~9000 – some degradation in comparison with the expected R~10000, due to instrument miss-alignment - spectral coverage: 1.479-1.775 (4 settings) and 2.079-2.424 microns (3 settings) - typical signal-to-noise ratio S/N~20-30, dominated by the systematics such as sky background and transmission variation - telluric standards: B-A stars at the same or similar airmass; the spectra of the program stars will be flux-calibrated Observations and Data Reduction

  7. MBR P123 K2I Teff=4293 K log g=+0.57 [Fe/H]=-0.70 Data Note Bene: this is a preliminary reduction! Note the telluric correction artifacts at ~1.75 and ~2.40 microns!

  8. MBR P123 K2I Teff=4293 K log g=+0.57 [Fe/H]=-0.70 Spectral Features

  9. - the main goals of this project are to improve the metallicity coverage of infrared spectral atlases for the red supergiants which dominate the near-IR continuum of starbursts - five red supergiants stars in the Small Magellanic Cloud were observed at medium-high spectral resolution (R~9000) with ISAAC at the VLT; one Galactic red giant and one Galactic red supergiant were observed for comparison purposes. Summary

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