Astron. Astrophys. 330, 578-584 (1998)

Infrared high angular resolution measurements of stellar sources ^*

III. Angular diameters and effective temperatures of eleven late-type giants

A. Richichi ¹, S. Ragland ¹ and L. Fabbroni <sup>2

1</sup> Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi, 5, I-50125 Firenze, Italy
² Dipartimento di Statistica, Viale Morgagni 59, I-50134 Firenze, Italy

Received 5 August 1997 / Accepted 25 August 1997

Abstract

Near-infrared lunar occultation observations of eleven late-type giants in the spectral range K0 to M6 (including one carbon star) are reported here. These stars are resolved from our observations carried out at 2.2 m, resulting in accurate determinations of their angular sizes, with values in the range 1.4 to 7.1 milliseconds of arc (mas) and a typical accuracy of 0.12 mas. Nine out of eleven sources are resolved for the first time.

In addition, near infrared photometric observations of some of the sources have been carried out to compute stellar bolometric fluxes, and hence derive the effective temperatures. Our accurate angular diameter measurements (at least in the case of eight sources) have the potential to provide effective temperatures with an accuracy less than 3 when bolometric fluxes become available with an accuracy less than 10 . The observed sources are discussed in conjunction with earlier high angular resolution observations and available photometric data. A comparison of the current performance of lunar occultations and long baseline inferferometry in the field of angular diameters and effective temperatures is presented.

Key words: occultation stars: fundamental parameters stars: late-type stars: circumstellar matter

* Based on observations collected at TIRGO (Gornergrat, Switzerland), at Calar Alto (Spain), and at the European Southern Observatory (La Silla, Chile). TIRGO is operated by CNR-CAISMI Arcetri, Italy. Calar Alto is operated by the German-Spanish Astronomical Center.

Send offprint requests to: A. Richichi (arichichi@arcetri.astro.it)

SIMBAD Objects

Contents

• 1. Introduction
• 2. Observations and data analysis
• 3. Results and discussion
  • 3.1. SW Gem
  • 3.2. T Ari
  • 3.3. IRC-20445
  • 3.4. IRC-20550
  • 3.5. AB Gem
  • 3.6. IRC + 20071
  • 3.7. IRC + 20141
  • 3.8. Bolometric fluxes and effective temperatures
• 4. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: January 16, 1998
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