J/A+A/612/A48 4 oxygen-rich evolved stars NH3 spectra (Wong+, 2018) ================================================================================ Circumstellar ammonia in oxygen-rich evolved stars. Wong K.T., Menten K.M., Kaminski T., Wyrowski F., Lacy J.H., Greathouse T.K. =2018A&A...612A..48W (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Stars, emission ; Stars, radio ; Planetary nebulae ; Stars, giant ; Stars, supergiant ; Radio lines ; Spectra, millimetric/submm ; Spectra, infrared Keywords: stars: AGB and post-AGB - circumstellar matter - supergiants - tars: winds, outflows - ISM: molecules - stars: mass-loss Abstract: The circumstellar ammonia (NH_3_) chemistry in evolved stars is poorly understood. Previous observations and modelling showed that NH_3_ abundance in oxygen-rich stars is several orders of magnitude above that predicted by equilibrium chemistry. We would like to characterise the spatial distribution and excitation of NH_3_ in the oxygen-rich circumstellar envelopes (CSEs) of four diverse targets: IK Tau, VY CMa, OH 231.8+4.2, and IRC +10420. We observed NH_3_ emission from the ground state in the inversion transitions near 1.3cm with the Very Large Array (VLA) and submillimetre rotational transitions with the Heterodyne Instrument for the Far-Infrared (HIFI) aboard Herschel Space Observatory from all four targets. For IK Tau and VY CMa, we observed NH_3_ rovibrational absorption lines in 2 band near 10.5um with the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared Telescope Facility (IRTF).We also attempted to search for the rotational transition within the excited vibrational state (v_2_=1) near 2mm with the IRAM 30m Telescope. Non-LTE radiative transfer modelling, including radiative pumping to the vibrational state, was carried out to derive the radial distribution of NH_3_ in the CSEs of these targets. We detected NH_3_ inversion and rotational emission in all four targets. IK Tau and VY CMa show blueshifted absorption in the rovibrational spectra. We did not detect vibrationally excited rotational transition from IK Tau. Spatially resolved VLA images of IK Tau and IRC +10420 show clumpy emission structures; unresolved images of VY CMa and OH 231.8+4.2 indicate that the spatial-kinematic distribution of NH_3_ is similar to that of assorted molecules, such as SO and SO2, that exhibit localised and clumpy emission. Our modelling shows that the NH_3_ abundance relative to molecular hydrogen is generally of the order of 10^-7^, which is a few times lower than previous estimates that were made without considering radiative pumping and is at least ten times higher than that in the carbon-rich CSE of IRC +10216. NH_3_ in OH 231.8+4.2 and IRC +10420 is found to emit in gas denser than the ambient medium. Incidentally, we also derived a new period of IK Tau from its V-band light curve. NH_3_ is again detected in very high abundance in evolved stars, especially the oxygen-rich ones. Its emission mainly arises from localised spatial-kinematic structures that are probably denser than the ambient gas. Circumstellar shocks in the accelerated wind may contribute to the production of NH_3_. Future mid-infrared spectroscopy and radio imaging studies are necessary to constrain the radii and physical conditions of the formation regions of NH_3_. Description: The catalogue contains radio (VLA), submillimetre (Herschel/HIFI), and mid-infrared (NASA IRTF/TEXES) spectra of ammonia emission or absorption from four oxygen-rich evolved stars, including IK Tau (AGB star), VY CMa (red supergiant), OH 231.8+4.2 (pre-planetary nebular), and IRC +10420 (yellow hypergiant). The scales of the VLA, Herschel/HIFI, and IRTF/TEXES are total flux (Jansky), main-beam brightness temperature (Kelvin), and relative intensity, respectively. The X-axis of the IRTF/TEXES spectra are in LSR velocity while that of the other spectra are in stellar rest frame (as in the paper). The positions of the objects are determined from the radio continuum of the VLA observations except for IRC +10420 of which the coordinates are taken from SIMBAD. The spectra are generated in FITS format with the GILDAS/CLASS software. Objects: ------------------------------------------------------ RA (2000) DE Designation(s) ------------------------------------------------------ 03 53 28.93 +11 24 21.5 IK Tau = V* IK Tau 07 22 58.33 -25 46 03.0 VY CMa = V* VY CMa 07 42 16.94 -14 42 49.8 OH 231.8+4.2 = V* QX Pup 19 26 48.10 +11 21 16.7 IRC +10420 = V* V1302 Aql ------------------------------------------------------ File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file list.dat 178 65 List of spectra fits/* . 65 Individual fits spectra -------------------------------------------------------------------------------- Byte-by-byte Description of file: list.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 12 A12 --- Star Star name 14- 22 F9.5 deg RAdeg Right Ascension of center (J2000) 23- 31 F9.5 deg DEdeg Declination of center (J2000) 33- 35 I3 --- Nx Number of pixels along X-axis 37- 59 A23 --- Obs.Date Observation date (YYYY-MM-DDThh:mm:ss.sss) 61- 69 F9.4 km/s bVel Lower value of velocity interval 71- 78 F8.4 km/s BVel Upper value of velocity interval 80- 86 F7.4 km/s dVel Velocity resolution 88- 89 I2 Kibyte size Size of FITS file 91-116 A26 --- FileName Name of FITS file, in subdirectory fits 118-178 A61 --- Title Title of the FITS file -------------------------------------------------------------------------------- Acknowledgements: Ka Tat Wong, ktwong(at)mpifr-bonn.mpg.de ================================================================================ (End) Ka Tat Wong [MPIfR/IRAM], Patricia Vannier [CDS] 20-Nov-2017