VLBA DETERMINATION OF THE DISTANCE TO NEARBY STAR-FORMING REGIONS. III. HP TAU/G2 AND THE THREE-DIMENSIONAL STRUCTURE OF TAURUS

By R. Torres, L. Loinard, A. Mioduszewski, Luis F. Rodriguez. 2009

136 citations recorded by the source corpus.

Using multiepoch Very Long Baseline Array (VLBA) observations, we have measured the trigonometric parallax of the weak-line T Tauri star HP Tau/G2 in Taurus. The best fit yields a distance of 161.2 ± 0.9 pc, suggesting that the eastern portion of Taurus (where HP Tau/G2 is located) corresponds to the far side of the complex. Previous VLBA observations have shown that T Tau, to the south of the complex, is at an intermediate distance of about 147 pc, whereas the region around L1495 corresponds to the near side at roughly 130 pc. Our observations of only four sources are still too coarse to enable a reliable determination of the three-dimensional structure of the entire Taurus star-forming complex. They do demonstrate, however, that VLBA observations of multiple sources in a given star-forming region have the potential not only to provide a very accurate estimate of its mean distance, but also to reveal its internal structure. The proper motion measurements obtained simultaneously with the parallax allowed us to study the kinematics of the young stars in Taurus. Combining the four observations available so far, we estimate the peculiar velocity of Taurus to be about 10.6 km s−1 almost completely in a direction parallel to the Galactic plane. Using our improved distance measurement, we have refined the determination of the position on the H–R diagram of HP Tau/G2, and of two other members of the HP Tau group (HP Tau itself and HP Tau/G3). Most pre-main-sequence evolutionary models predict significantly discrepant ages (by 5 Myr) for those three stars—expected to be coeval. Only in the models of Palla & Stahler do they fall on a single isochrone (at 3 Myr).

Subfields: Astronomy and Astrophysics, Instrumentation

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In Astronomy and Astrophysics

1. K. Luhman
2. S. Andrews
3. D. Wilner
4. A. Kraus
5. T. Birnstiel
6. Michael C. Liu
7. L. Hillenbrand
8. T. Dupuy

In Instrumentation

1. K. Luhman
2. Michael C. Liu
3. S. Andrews
4. T. Birnstiel
5. A. Kraus
6. T. Dupuy
7. D. Wilner
8. K. Allers

Citations in the corpus

• A millimeter Continuum Size–Luminosity Relationship for Protoplanetary Disks (2017, methodology): “We assign the same parallax for HP Tau that was measured for its wide companion, HP Tau/G2, using VLBI radio observations (Torres et al. 2009).”
• TADPOL: A 1.3 mm SURVEY OF DUST POLARIZATION IN STAR-FORMING CORES AND REGIONS (2013, background): “DG Tau DG Tau is a Class II, 0.67M K5-M0 T Tauri star (Güdel et al. 2007, and references therein) located at a distance of roughly 140 pc in the Taurus-Auriga star-forming association (Kenyon et al. 1994; Torres et al. 2009).”
• RESOLVED IMAGES OF LARGE CAVITIES IN PROTOPLANETARY TRANSITION DISKS (2011, background): “The primary star of a wide multiple system in Taurus (d ≈ 140pc; see Torres et al. 2009), UX Tau A is the only component with evidence for remnant disk material (e.g., White & Ghez 2001; McCabe et al. 2006).”
• LkCa 15: A YOUNG EXOPLANET CAUGHT AT FORMATION? (2011, methodology): “…contrasts can be converted into absolute magnitudes using the observed photometry for LkCa15 A (Appendix A) and the distance to Taurus-Auriga, 145±15 pc (Torres et al. 2009); the combined absolute magnitude and color for all three components are ML′ = 6.8 ± 0.2 mag and K ′ − L′ = 1.7 ± 0.2 mag.”
• MAPPING THE SHORES OF THE BROWN DWARF DESERT. II. MULTIPLE STAR FORMATION IN TAURUS–AURIGA (2011, background): “…a characteristic distance for all Taurus members of 145±15 pc. Recent high-precision parallax measurements with the VLBA (Loinard et al. 2007; Torres et al. 2007, 2009) and from binary orbit fitting (Boden et al. 2007) suggest that there might be a distance gradient of 165-125 pc in the…”
• THE MASS DEPENDENCE BETWEEN PROTOPLANETARY DISKS AND THEIR STELLAR HOSTS (2013, result): “Historical spectroscopic parallax estimates have favored a mean distance of d ≈ 140 ± 20 pc to the association, in good agreement with a few precise, individual trigonometric parallaxes from VLBI measurements (Loinard et al. 2007; Torres et al. 2009, 2012).”
• THE TAURUS SPITZER SURVEY: NEW CANDIDATE TAURUS MEMBERS SELECTED USING SENSITIVE MID-INFRARED PHOTOMETRY (2009, background): “At just 137 pc (with a depth of ∼ 20 pc; Torres et al. 2007, 2009), the Taurus star-forming region is one of the closest large cloud complexes with hundreds of low-mass stars, ongoing star formation, and objects ranging in age up to ∼5 Myr.”
• AN INFRARED/X-RAY SURVEY FOR NEW MEMBERS OF THE TAURUS STAR-FORMING REGION (2009, methodology): “Since accurate distances are available only for a few individual stars (Torres et al. 2009), we have adopted a distance of 140± 10 pc for each group.”
• AN OPTICAL SPECTROSCOPIC STUDY OF T TAURI STARS. I. PHOTOSPHERIC PROPERTIES (2014, background): “Table 9 lists the most significant changes in Taurus spectral types, relative to the compilation of spectral types by Luhman et al. (2010).”
• Microarcsecond Radio Astrometry (2013, unknown): “The Taurus molecular cloud has been well studied and parallaxes for five YSOs have been reported from VLBA observations in a series of papers (Loinard et al. 2005, 2007; Torres et al. 2007, 2009, 2012).”
• THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, result): “Our CFHT parallax puts this at a distance (240+70−40 pc) that is marginally consistent with the young stars in Taurus (130–160 pc; Torres et al. 2009).”
• Fundamental Parameters of the Milky Way Galaxy Based on VLBI Astrometry (2012, unknown): “…et al. 2012, (28) Sanna et al. 2009, (29) Sanna et al. 2012, (30) Sato et al. 2008, (31) Sato et al. 2010a, (32) Sato et al. 2010b, (33) Shiozaki et al. 2011, (34) Torres et al. 2007, (35) Torres et al. 2009, (36) Xu et al. 2006, (37) Xu et al. 2009, (38) Xu et al. 2011, (39) Zhang et al. 2009.”