Astron. Astrophys. 327, 337-341 (1997)

Diffuse interstellar bands near 9600 Å: not due to C60 yet

P. Jenniskens ¹, G. Mulas ², I. Porceddu ³ and P. Benvenuti <sup>2, 4, 5

1</sup> The SETI Institute at NASA/Ames Research Center, Mail-Stop 239-4, Moffett Field, CA 94035-1000, USA
² Dipartimento di Scienze Fisiche dell'Universita di Cagliari, Via Ospedale 72, I-09124 Cagliari, Italy
³ Osservatorio Astronomico di Cagliari, Str. 54, Loc. Poggio dei Pini, I-09012 Capoterra (CA), Italy
⁴ Space Telescope European Coordinating Facility, European Southern Observatory, Germany
⁵ Affiliated with the Astrophysics Division, SSD-ESA

Received 24 December 1996 / Accepted 6 June 1997

Abstract

High spectral resolution studies of the two Diffuse Interstellar Bands (DIB) previously assigned to C60 ( 9577 and 9632) confirm that these DIBs have the same full-width-at-half-maximum and behave similarly in dense cloud environments where the DIBs are weakened relative to the diffuse interstellar medium. Their relative strength, however, is less than previously reported and differs from the relative intensities measured from matrix isolation spectroscopy. A simultaneous search for the two laboratory derived vibronic tranistions of C60 at about 9366 and 9419 Å has not lead to the detection of the two weak counterparts stronger than 15% of 9577. We conclude that for the diffuse band spectrum to be consistent with C60, not only the measured band positions have to be slightly different in the gas-phase, but also the relative intensity of the two main lines has to differ significantly from that of the known laboratory data.

Key words: ISM: molecules - line: identification

Send offprint requests to: P. Jenniskens

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Contents

• 1. Introduction
• 2. The observations
• 3. Results
  • 3.1. The 9600Å window
  • 3.2. The 9400 Å window
• 4. Discussion
• 5. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998
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