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Astron. Astrophys. 321, 24-28 (1997)

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The gravitational lensing nature of the Cloverleaf unveiled in CO (7-6) line emission *

D. Alloin 1, S. Guilloteau 2, R. Barvainis 3, R. Antonucci 4 and L. Tacconi 5

1 Service d'Astrophysique, CE Saclay, F-91191 Gif-sur-Yvette Cedex, France
2 Institut de Radio Astronomie Millimétrique, 300 Rue de la Piscine, F-38406 Saint Martin d'Hères, France
3 MIT Haystack Observatory, Westford, MA 01886 USA
4 UC Santa Barbara, Physics Department, Santa Barbara, CA 93106 USA
5 Max Planck Institut fur extraterrestrische Physik, D-85748 Garching Germany

Received 11 December 1996 / Accepted 27 February 1997


We report [FORMULA] resolution imaging of the Cloverleaf quasar in the CO(7-6) line and 1.3 mm continuum,, as well as [FORMULA] resolution imaging in the CO(3-2) line, performed with the IRAM interferometer. The CO(7-6) image is clearly resolved into 4 spots, demonstrating that the CO emission is also gravitationally lensed. We do not find any convincing evidence for a velocity gradient in the maps. As compared to the optical spots from a V band HST image, some of the CO spots are found to be stretched along the Einstein ring. Using the available lens model for the Cloverleaf, this suggests an intrinsic radius of [FORMULA] pc for the CO emitting region. No continuum emission is detected: the measured flux density is [FORMULA] mJy, consistent with a spectral index larger than 3.

Key words: quasars: H 1413+117 – gravitational lensing – radio lines: ISM

* Based on observations at the Institut de Radio Astronomie Millimétrique, supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain)

Send offprint requests to: D.Alloin

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998