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Astron. Astrophys. 335, 522-532 (1998)

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5. Conclusions

We have used ISOCAM photometry to obtain mid infrared photometry of a sample of low mass embedded objects in [FORMULA] Ophiuchi. Combining these data with near infrared groundbased measurements provides strong constraints on models of these sources. We use a technique which simultaneously fits to the extinction, infrared excess, luminosity, and temperature of the object to derive the intrinsic properties of these sources.

Seven of these sources have spectroscopically determined temperatures. The values derived from our fitting are in all seven cases in good agreement. We conclude that the isochrone fitting technique can reliably estimate the source properties when data over the full spectral range of 1 to 6µm are available. We also show that similar modeling based on groundbased data alone (CRBR, Strom et al. 1995) can generally yield reasonably good estimates of the source parameters. Thus, for statistical evaluation of large samples of objects, modeling of groundbased photometry should be valid. However, the example of 2317.5-1729 (whose mass appears to be significantly underestimated from the groundbased data) is a caution about relying on such data for individual objects.

Based on the fits to the photometry, three of the sources in our sample are low mass brown dwarfs (of which two have spectroscopically determined temperatures in agreement with this designation). Five sources are transitional objects, either high mass brown dwarfs or very low mass stars. Three objects appear to be unequivocally young stars. Although the sample was selected to favor previously identified brown dwarf candidates, the results of our new analysis favor our previous arguments (CRBR; Williams et al. 1995; Comerón et al. 1996) that the IMF in [FORMULA] Ophiuchi does not drop precipitously at the bottom of the main sequence.

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© European Southern Observatory (ESO) 1998

Online publication: June 18, 1998
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