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Astron. Astrophys. 361, 660-670 (2000)

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Young stellar clusters and H2 nebulosities in S233IR * **

A. Porras 1, I. Cruz-González 2 and L. Salas 3

1 Instituto Nacional de Astrofísica, Optica y Electrónica, Apartado Postal 216, Puebla, Pue. 72000, México (aporras@inaoep.mx)
2 Instituto de Astronomía, UNAM, Apartado Postal 70-264, C.U., México, D.F. 04510, México (irene@astroscu.unam.mx)
3 Instituto de Astronomía, UNAM, Apartado Postal 877, Ensenada, B.C. 22830, México (salas@astrosen.unam.mx)

Received 11 January 2000 / Accepted 30 June 2000

Abstract

We present an infrared photometric study of the star formation region associated to IRAS 05358+3543, hereafter designated S233IR. Several manifestations of star formation activity are present in S233IR: masers, molecular outflow, GMC core, YSOs, young stellar clusters and an IRAS source. The paper includes photometric J, H, K and H2 (2.12 µm) images and scanning Fabry-Perot observations to study H2 kinematics. In the 3.6´[FORMULA]3.6´ observed field, two distinct young stellar clusters separated by 0.5 pc are found, one being much redder than the other by AV [FORMULA] 7 mag. A collection of PMS objects and several H2 nebulosities associated to the younger and redder NE cluster are found. Two deeply embedded jet/counter-jet structures, produced by shocked H2 gas, are detected near the core of the molecular outflow. Possible exciting source candidates of the molecular outflow and H2 nebula are discussed. The velocity field of H2 gas shows that the bulk of the emission occurs within -36.9 to 2.3 km/s. Individual spectra of H2 nebulosities show peak velocities consistent with the rest velocity of the GMC and H2O maser peak velocities. Luminosity function histograms are used to obtain a crude age estimate for cluster and field stars: [FORMULA]2 Myr for NE cluster, 3 Myr for SW cluster and 6 Myr for field (distributed population) stars; indicating at least two star formation stages and a distributed population of young stars. Finally, from PMS isochrones and NIR photometry, taking care of completeness limits, we estimate stellar masses to study the IMF. A turnover for low-mass-stars is found for the SW cluster, while field stars show a Salpeter IMF.

Key words: stars: early-type – stars: formation – stars: mass-loss – ISM: individual objects: S233IR – ISM: jets and outflows

* Based on observations obtained at the Observatorio Astronómico Nacional at San Pedro Mártir, B.C., México.
** Table 1 is only available in electronic form at the CDS via anonymous ftp to ftp://cdsarc.u-strasbg.fr/pub/cats/J/A+A/361/660 (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/361/660

Send offprint requests to: I. Cruz-González

Correspondence to: irene@astroscu.unam.mx

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© European Southern Observatory (ESO) 2000

Online publication: October 2, 2000
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