Proper Motions of the Jets in the Region of HH 30 and HL/XZ Tau: Evidence for a Binary Exciting Source of the HH 30 Jet

Abstract

We present [S ii] images of the HH 30 and HL/XZ Tau region obtained at two epochs, as well as long-slit optical spectroscopy of the HH 30 jet. We measured proper motions of $100Y300 km s À1 for the HH 30 jet and counterjet and of $120 km s À1 for the HL Tau jet. Inclination angles with respect to the plane of the sky are 0 Y40 for the HH 30 jet and 60 for the HLTau jet. Comparison with previous observations suggests that most of the jet knots consist of persistent structures. Also, we corroborate that the HH 30-N knots correspond to the head of the HH 30 jet. The overall HH 30 jet structure can be well described by a wiggling ballistic jet, arising either from orbital motion of the jet source around a primary or from precession of the jet axis because of the tidal effects of a companion. In the first scenario, the orbital period would be 53 yr and the total mass 0.25Y2 M . In the precession scenario, the mass of the jet source would be $0.1Y1 M , the orbital period <1 yr, and the mass of the companion less than a few times 0.01 M , thus being a substellar object or a giant exoplanet. In both scenarios a binary system with a separation <18 AU (<0.13 00 ) is required. Since the radius of the flared disk observed with the HST is $250 AU, we conclude that this disk appears to be circumbinary rather than circumstellar, suggesting that the search for the collimating agent of the HH 30 jet should be carried out at much smaller scales.

Kinematics and the origin of the internal structures in HL Tauri jet (HH 151)

“…The present PM values are more similar to the results of Anglada et al (2007) than to the higher estimates of Mundt et al (1990) and Movsessian et al (2007). Very probably this discrepancy results from the unavoidable systematic errors of various origin, which were briefly discussed also in Sect.…”

“…In addition, these knots also demonstrate perceptible proper motions, which were first studied by Mundt et al (1990). Other data, presented in the papers of Movsessian et al (2007) and Anglada et al (2007), showed a certain difference between the proper motions (PM) of the knots, obtained in Hα and [S ii] emission lines. A&A 541, A16 (2012) There are various theoretical approaches to explain the formation of knotty structures in the jets .…”

The circumstellar disk of HH 30

“…Most research has been conducted in the optical and NIR band including photometry, polarimetry, medium-resolution imaging and high-resolution spectroscopy with ground-based instruments (Vrba et al 1985;Appenzeller et al 2005;Anglada et al 2007) and high-resolution imaging with the Hubble Space Telescope (HST) from outside the atmosphere (B96; C01;Watson & Stapelfeldt 2004, hereafter W04). The SED in the MIR has been measured with ISOCAM/ISO (Stapelfeldt & Moneti 1999;Brandner et al 2000) and refined substantially by observations with IRS on the Spitzer Space Telescope (SST, Furlan et al 2008).…”

“…Effective temperature and luminosity are consistent with a contracting protostar of spectral class M3 ± 2 with R * ∼ 2 R (Simon et al 2000), but it is very difficult to constrain the properties of the central source and a binary, as proposed by Anglada et al (2007) and G08, seems a viable option.…”

“…Observed photometric and polarimetric variability of HH 30 shows periodicity on the scale of a few days and seems to be caused by either a light-house effect, periodic shadowing by infalling matter, or a close companion Duran-Rojas et al 2009). The impressive dynamic bipolar jet features an undulating morphology and ballistic motion that can be explained by orbital motion or precession of the source due to gravitational interaction with a partner separated by <18 AU (Anglada et al 2007). The jet is associated with an entrained conical molecular outflow featuring an opening angle of ∼30 • (P06), whose morphology is consistent with a close binary (Tambovtseva et al 2008).…”