Registration of H2O and SiO masers in the Calabash Nebula to confirm the planetary nebula paradigm

We report on the astrometric registration of VLBI images of the SiO and water masers in OH231.8+4.2, the iconic Proto-Planetary Nebula also known as the Calabash nebula, using the KVN and Source/Frequency Phase Referencing. This, for the first time, robustly confirms the alignment of the SiO masers, close to the AGB star, driving the bi-lobe structure with the water masers in the out-flow. We are able to trace the bulk motions for the water masers over the last few decades to be 19 km/s and deduce that the age of this expansion stage is 38$\pm$2 years. The combination of this result with the distance allows a full 3D reconstruction, and confirms that the water masers lie on and expand along the known large-scale symmetry axis and that the outflow is only a few decades old, so mass loss is almost certainly on-going. Therefore we conclude that the SiO emission marks the stellar core of the nebular, the water emission traces the expansion, and that there must be multiple epochs of ejection to drive the macro-scale structure.

[1]  R. Dodson,et al.  The Power of (Near) Simultaneous Multi-Frequency Observations for mm-VLBI and Astrometry , 2017 .

[2]  I. Gatley,et al.  Variation in the near-infrared surface brightness distribution of the bipolar nebula OH 231.8 + 4.2 , 1992 .

[3]  Min-Gyu Song,et al.  ASTROMETRICALLY REGISTERED SIMULTANEOUS OBSERVATIONS OF THE 22 GHz H2O AND 43 GHz SiO MASERS TOWARD R LEONIS MINORIS USING KVN AND SOURCE/FREQUENCY PHASE REFERENCING , 2014, 1408.3513.

[4]  C. Contreras,et al.  Submilliarcsecond-resolution mapping of the 43 GHz SiO maser emission in the bipolar post-AGB nebula OH231.8+4.2 , 2002 .

[5]  C. Contreras,et al.  Water vapor and silicon monoxide maser observations in the protoplanetary nebula OH 231.8+4.2 , 2007, 0704.2166.

[6]  Sang-Sung Lee,et al.  VERIFICATION OF THE ASTROMETRIC PERFORMANCE OF THE KOREAN VLBI NETWORK, USING COMPARATIVE SFPR STUDIES WITH THE VLBA AT 14/7 mm , 2014, 1407.4604.

[7]  R. Neri,et al.  The highly collimated bipolar outflow of OH 231.8+4.2 ? , 2001 .

[8]  A. Castro-Carrizo,et al.  Mass, linear momentum and kinetic energy of bipolar flows in protoplanetary nebulae , 2001 .

[9]  Yong-Sun Park,et al.  SiO AND H2O MASER SURVEY TOWARD POST-ASYMPTOTIC GIANT BRANCH AND ASYMPTOTIC GIANT BRANCH STARS , 2014 .

[10]  R. Sahai,et al.  HST observations of the protoplanetary nebula OH 231.8+4.2: The structure of the jets and shocks , 2002 .

[11]  Bruce Balick,et al.  Shapes and Shaping of Planetary Nebulae , 2002 .

[12]  Yoshiharu Asaki,et al.  Verification of the Effectiveness of VSOP-2 Phase Referencing with a Newly Developed Simulation Tool, ARIS , 2007, 0707.0558.

[13]  Do-Young Byun,et al.  Korean VLBI Network Receiver Optics for Simultaneous Multifrequency Observation: Evaluation , 2013 .

[14]  Richard Dodson,et al.  THE POWER OF SIMULTANEOUS MULTIFREQUENCY OBSERVATIONS FOR mm-VLBI: ASTROMETRY UP TO 130 GHz WITH THE KVN , 2015, 1509.02621.

[15]  K. Sellgren,et al.  Near-infrared polarization in the bipolar outflow OH 0739-14 , 1995 .

[16]  M. Cohen,et al.  STUDIES OF BIPOLAR NEBULAE. VII. THE EXCITING STAR OF OH 0739-14 (= OH 231.8+4.2) , 1981 .

[17]  28 SiO v = 1 and v = 2, J = 1-0 maser variability in evolved stars. Eleven years of short spaced monitoring , 2004 .

[18]  R. Sahai,et al.  The Companion to the Central Mira Star of the Protoplanetary Nebula OH 231.8+4.2 , 2004 .

[19]  Richard Dodson,et al.  HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD FOR ATMOSPHERIC CALIBRATION , 2011, 1101.2051.

[20]  Richard Dodson,et al.  The Science Case for Simultaneous mm-Wavelength Receivers in Radio Astronomy , 2017, 1709.07167.

[21]  A. Kemball,et al.  Rotten Egg nebula: the magnetic field of a binary evolved star , 2012, 1201.3839.