The evolution of M 2–9 from 2000 to 2010

Abstract

Context. Understanding the formation of collimated outflows is one of the most debated and controversial topics in the study of the late stages of stellar evolution. Aims. M 2-9 is an outstanding representative of extreme aspherical flows. It presents unique features such as a pair of high-velocity dusty polar blobs and a mirror-symmetric rotating pattern in the inner lobes. Their study provides important information on the nature of the poorly understood central source of M 2-9 and its nebula. Methods. Imaging monitoring at sub-arcsec resolution of the evolution of the nebula in the past decade is presented. Spectroscopic data provide complementary information. Results. We determine the proper motions of the dusty blobs, which infer a new distance estimate of 1.3 ± 0.2 kpc, a total nebular size of 0.8 pc, a speed of 147 km s −1 , and a kinematical age of 2500 yr. The corkscrew geometry of the inner rotating pattern is confirmed and quantified. Different recombination timescales for different ions explain the observed surface brightness distribution. According to the images taken after 1999, the pattern rotates with a period of 92 ± 4 years. On the other hand, the analysis of images taken between 1952 and 1977 measures a faster angular velocity. If the phenomenon were related to orbital motion, this would correspond to a modest orbital eccentricity (e = 0.10 ± 0.05), and a slightly shorter period (86 ± 5 years). New features have appeared after 2005 on the west side of the lobes and at the base of the pattern. Conclusions. The geometry and travelling times of the rotating pattern support our previous proposal that the phenomenon is produced by a collimated spray of high velocity particles (jet) from the central source, which excites the walls of the inner cavity of M 2-9, rather than by a ionizing photon beam. The speed of such a jet would be remarkable: between 11 000 and 16 000 km s −1 . The rotatingjet scenario may explain the formation and excitation of most of the features observed in the inner nebula, with no need for additional mechanisms, winds, or ionization sources. All properties point to a symbiotic-like interacting binary as the central source of M 2-9. The new distance determination implies system parameters that are consistent with this hypothesis.

A morpho-kinematic and spectroscopic study of the bipolar nebulae: M 2−9, Mz 3, and Hen 2−104

“…Its bipolar structure contains two separate shells, an inner bulb and an outer neutral shell (Corradi et al 2011), which are thought to be formed from two equatorial rings/tori (Castro-Carrizo et al 2012) found at the nebula's centre. The nebula also has a feathered component which extends all the way out to a pair of dusty blobs.…”

“…Here, two well known extreme bPNe (M 2−9 and Mz 3) and one confirmed symbiotic nebula (Hen 2−104) are investigated. It has been proposed that a SySt mechanism has led to the formation of M 2−9 (Doyle et al 2000;Livio & Soker 2001;Schmeja & Kimeswenger 2001;Smith & Gehrz 2005;Corradi et al 2011), Mz 3 (Schmeja & Kimeswenger 2001;Guerrero et al 2004;Smith & Gehrz 2005), and Hen 2−104 (Whitelock 1987;Lutz et al 1989;Schwarz et al 1989;Corradi et al 2001;Santander-García et al 2008).…”

“…It is generally accepted that accretion disks are needed to launch jets and possibly ansae (Gonçalves et al 2001;Crocker et al 2002;Corradi 2003;Sokoloski 2003;Corradi et al 2011;Werner et al 2014).…”

The growth of the outflows from evolved stars: A live poster

“…The unique property of this object is its 90-yr rotating pattern in the inner lobes. Given its corkscrew geometry and associated travelling times, excitation structure, we conclude that the phenomenon is caused by a particle jet from the central source hitting and exciting the walls of the inner lobes of M2-9 (Corradi et al 2011). The speed of the jet -between 11000 and 16000 km s −1 -would be unusually high among PNe and symbiotic stars.…”

Discovery of a planetary nebula surrounding the symbiotic star DT Serpentis

“…Nebulae have also been discovered around symbiotic stars that harbor non-Mira cool giants: AS 201 (Schwarz 1991) and CH Cyg (Corradi et al 2001b). Bipolar planetary nebulae like M 2-9 (Corradi et al 2011) and Mz 3 (Guerrero et al 2004;Santander-García et al 2004) that may possibly host a symbiotic nucleus (Schmeja & Kimeswenger 2001) are relevant bridges between symbiotic binaries and aspherical planetary nebulae.…”