The 2014 Alma Long Baseline Campaign: First Results From High Angular Resolution Observations Toward The Hl Tau Region

C. L. Brogan 1 L. M. Pérez 2 T. R. Hunter 1 W. R. F. Dent 3, 4 A. S. Hales 1, 4 R. E. Hills 5 S. Corder 1, 4 E. B. Fomalont 1, 4 C. Vlahakis 4, 3 Y. Asaki 6, 7 D. Barkats 4, 3 A. Hirota 4, 7 J. A. Hodge 1 C. M. V. Impellizzeri 1, 4 R. Kneissl 4, 3 E. Liuzzo 8 R. Lucas 9 N. Marcelino 8 S. Matsushita 10 K. Nakanishi 4, 7 N. Phillips 4, 3 A. M. S. Richards 11 I. Toledo 4 R. Aladro 3 D. Broguiere 12 J. R. Cortes 1, 4 P. C. Cortes 1, 4 D. Espada 4, 7 F. Galarza 4 D. Garcia- Appadoo 4, 3 L. Guzman- Ramirez 3 E. M. Humphreys 13 T. Jung 14 S. Kameno 4, 7 R. A. Laing 13 S. Leon 4, 3 G. Marconi 4, 3 A. Mignano 8 B. Nikolic 5 L.-A. Nyman 4, 3 M. Radiszcz 4 A. Remijan 1, 4 J. A. Rodón 3 T. Sawada 4, 7 S. Takahashi 4, 7 R. P. J. Tilanus 15 B. Vila Vilaro 4, 3 L. C. Watson 3 T. Wiklind 4, 3 E. Akiyama 7 E. Chapillon 16, 12 I. de Gregorio- Monsalvo 4, 3 J. Di Francesco 17 F. Gueth 12 A. Kawamura 7 C.-F. Lee 10 Q. Nguyen Luong 7 J. Mangum 1 V. Pietu 12 P. Sanhueza 7 K. Saigo 7 S. Takakuwa 10 C. Ubach 1 T. Van Kempen 15 A. Wootten 1 A. Castro- Carrizo 12 H. Francke 3 J. Gallardo 4 J. Garcia 4 S. Gonzalez 4 T. Hill 4, 3 T. Kaminski 3 Y. Kurono 4, 7 H.-Y. Liu 10 C. Lopez 4 F. Morales 4 K. Plarre 4 G. Schieven L. Testi 13 L. Videla 4 E. Villard 4, 3 P. Andreani 13 J. E. Hibbard 1 K. Tatematsu 7
Abstract : We present Atacama Large Millimeter/submillimeter Array (ALMA) observations from the 2014 Long Baseline Campaign in dust continuum and spectral line emission from the HL Tau region. The continuum images at wavelengths of 2.9, 1.3, and 0.87 mm have unprecedented angular resolutions of 0.″ 075 (10 AU) to 0.″ 025 (3.5 AU), revealing an astonishing level of detail in the circumstellar disk surrounding the young solar analog HL Tau, with a pattern of bright and dark rings observed at all wavelengths. By fitting ellipses to the most distinct rings, we measure precise values for the disk inclination (46\buildrel{\circ}\over{.} 72+/- 0\buildrel{\circ}\over{.} 05) and position angle (+138\buildrel{\circ}\over{.} 02+/- 0\buildrel{\circ}\over{.} 07). We obtain a high-fidelity image of the 1.0 mm spectral index (α), which ranges from α ∼ 2.0 in the optically thick central peak and two brightest rings, increasing to 2.3–3.0 in the dark rings. The dark rings are not devoid of emission, and we estimate a grain emissivity index of 0.8 for the innermost dark ring and lower for subsequent dark rings, consistent with some degree of grain growth and evolution. Additional clues that the rings arise from planet formation include an increase in their central offsets with radius and the presence of numerous orbital resonances. At a resolution of 35 AU, we resolve the molecular component of the disk in HCO+ (1-0) which exhibits a pattern over LSR velocities from 2–12 km s‑1 consistent with Keplerian motion around a ∼1.3 {M}ȯ star, although complicated by absorption at low blueshifted velocities. We also serendipitously detect and resolve the nearby protostars XZ Tau (A/B) and LkHα358 at 2.9 mm.
Type de document :
Article dans une revue
Astrophysical Journal Letters, 2015, 808 (1), 〈10.1088/2041-8205/808/1/L3〉
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https://hal.archives-ouvertes.fr/hal-01179310
Contributeur : Marie-Paule Pomies <>
Soumis le : mercredi 22 juillet 2015 - 11:11:07
Dernière modification le : lundi 4 septembre 2017 - 12:26:24

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C. L. Brogan, L. M. Pérez, T. R. Hunter, W. R. F. Dent, A. S. Hales, et al.. The 2014 Alma Long Baseline Campaign: First Results From High Angular Resolution Observations Toward The Hl Tau Region. Astrophysical Journal Letters, 2015, 808 (1), 〈10.1088/2041-8205/808/1/L3〉. 〈hal-01179310〉

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