Astronomy & Astrophysics

All Tables

Table 1: Sample of protostars surveyed in Taurus. The infrared photometry and the spectral indices are taken from Kenyon & Hartmann (1995), except for IRAS 04191+1523, whose JHK photometry is from the 2MASS database and classification from Motte & André (2001). The bolometric luminosities are from Motte & André (2001). IRAS did not resolve the systems IRAS 04108+2803 AB and IRAS 04181+2654 AB and we assigned the same spectral index, based on unresolved photometry, to both components and split evenly the bolometric luminosity of the later system. The classification of each source is based on the infrared spectral indices (see text); "I'' stands for Class I sources and "FS'' for flat spectrum sources. The last three columns indicate whether the source i) has at least one visual companion within 10 $^{\prime \prime }$ , ii) is surrounded by an extended nebulosity in our images (see also Park & Kenyon 2002), and iii) has an extended (>1000 AU) envelope as seen in millimeter continuum mapping (from Motte & André 2001).
Table 2: Sample of protostars surveyed in Ophiuchus. ISO numbers, infrared spectral indices and bolometric luminosities are from Bontemps et al. (2001), while the near-infrared magnitudes are from Barsony et al. (1997), Greene et al. (1994) and the 2MASS database (2MASS uses a $K{\rm s}$ filter rather than a K filter; the difference in magnitude for an object can reach a few tenths of a magnitude). The source marked with a $\dagger$ symbol has an infrared spectral index typical of a normal Class II source but Ressler & Barsony (2001) have shown that this system contains a Class I source and it is classified as such here. The last three columns have the same meaning as in Table 1. The existence of an envelope is taken either from André & Montmerle (1994) and Motte et al. (1998) or from our reexamination of the mosaic presented in the latter. (Note that this classification is more uncertain than in Taurus due to the smaller size of protostellar envelopes in Ophiuchus. Particularly uncertain cases are flagged with a "?''.)
Table 3: List of all companions detected within 10 $^{\prime \prime }$ (Ophiuchus) or 30 $^{\prime \prime }$ (Taurus) of our targets. Flux ratios are measured with respect to the brightest component in the K band image, except for three systems where the Class I source is the faintest component in the near-infrared ( $\dagger$ symbol). The boldfaced entries represent systems that are likely to be physically bound (see Sect. 3.3). The two companions to IRS 54 listed in italics were detected by combining a short and a long exposure and are not included in our survey. Upper limits for flux ratios are at the 3 $\sigma$ level. IRAS 04264+2433 was saturated in all of our images, so only a lower limit for the flux ratio to its companion can be obtained.
Table 4: Observed companion star fraction over the separation range 110-1400 AU in Perseus, Taurus-Auriga and Ophiuchus star-forming regions (SFRs) for Class 0 sources, Class I sources with (env+) and without (env-) an extended millimetric envelope, and for Class II-III T Tauri stars in the same clouds. For comparison, the multiplicity rate for G-type field dwarfs over the same separation range is 14% (Duquennoy & Mayor 1991). References: 1 - Looney et al. (2000); 2 - this study; 3 - Mathieu (1994); 4 - Barsony et al. (2003).
Table A.1: List of all T Tauri stars (Class II and III objects) in Ophiuchus that were detected in the vicinity of our target protostars. Objects whose name starts with "B'' are from Barsony et al. (1997). The classification is determined from the infrared spectral indices following Bontemps et al. (2001).
Table A.2: List of all companions to T Tauri stars in Ophiuchus that were detected in the course of our survey.