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Astron. Astrophys. 357, 681-685 (2000)


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The distance to the nearest star-forming clouds: MBM12 and MBM20

T. Hearty 1, M. Fernández 1, J.M. Alcalá 2, E. Covino 2 and R. Neuhäuser 1

1 Max-Planck-Institut für Extraterrestrische Physik, 85740 Garching, Germany
2 Osservatorio Astronomico di Capodimonte, 80131 Napoli, Italy

Received 4 January 2000 / Accepted 3 February 2000

Abstract

We present high-resolution spectra (R [FORMULA] 49,000) of stars that have parallax measurements from the Hipparcos satellite and are projected along the line of sight to the two nearest known star forming clouds to the Sun: MBM12 and MBM20. The spectra were obtained with the FOCES Echelle Spectrograph at the 2.2 meter telescope in Calar Alto, Spain and the wavelength range was chosen to include the interstellar NaI D lines at [FORMULA] Å and [FORMULA] Å. Since the stars are at a range of distances, we use their spectra along with their parallaxes from Hipparcos to determine the distance to the molecular gas. The stars in front of the cloud do not show interstellar NaI D absorption features while the stars behind the cloud do show interstellar absorption features. We find that both clouds are somewhat more distant than previously estimated. The revised distance to MBM12 is 58[FORMULA]5 pc [FORMULA] 90[FORMULA]12 pc and the distance to MBM20 is [FORMULA] pc [FORMULA] [FORMULA] pc.

Key words: stars: formation – ISM: clouds – ISM: individual objects: MBM12 – ISM: individual objects: MBM20

Send offprint requests to: thearty@xray.mpe.mpg.de

© European Southern Observatory (ESO) 2000

Online publication: June 5, 2000

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