Po-Jian Chiu et al. 2006 ApJ 645 605 doi:10.1086/504309
Po-Jian Chiu1,2, Chi-Thiem Hoang2, Dinh-V-Trung2, Jeremy Lim2, Sun Kwok2, Naomi Hirano2 and C. Muthu2
Show affiliationsWe study the molecular outflow of the nearby evolved S star π1 Gru. We imaged the outflow in CO J = 2-1 and dust continuum with the Submillimeter Array. The CO emission was detected over a very broad velocity width of ~90 km s-1. Our high-resolution images show that the outflow at low velocities (≤15 km s-1) is elongated east-west and at high velocities (≥25 km s-1) is displaced north (at redshifted velocities) and south (blueshifted velocities) of center as defined by the dust continuum source. We model the spatial-kinematic structure of the low-velocity outflow as a flared disk with a central cavity of radius 200 AU and an expansion velocity of 11 km s-1, inclined by 55° to our line of sight. We attribute the high-velocity component to a bipolar outflow that emerges perpendicular to this disk with a velocity of up to ~45 km s-1. This high-velocity outflow may play an important role in shaping the gas envelope previously ejected by the AGB star and thus produce a bipolar morphology when the object evolves into a proto-planetary nebula.
circumstellar matter; stars: AGB and post-AGB; stars: individual (π Gruis)
Issue 1 (2006 July 1)
Received 2005 October 18, accepted for publication 2006 March 15
Po-Jian Chiu et al. 2006 ApJ 645 605
T. Sakamoto et al. 2004 ApJ 602 875
Koujin Takeda et al 2005 J. Phys. A: Math. Gen. 38 3751
P Catravas et al 2001 Meas. Sci. Technol. 12 1828
R. Atkins et al. 2003 ApJ 595 803
B. Sargent et al. 2006 ApJ 645 395
E A Hinds and I G Hughes 1999 J. Phys. D: Appl. Phys. 32 R119
M J Davis et al 2001 J. Phys. B: At. Mol. Opt. Phys. 34 4487
Augusto Damineli 1996 ApJ 460 L49
Angelos Vourlidas et al 2007 ApJ 668 L79