The Herschel view of the nebula around the luminous blue variable star AG Carinae

Abstract

Far-infrared Herschel PACS imaging and spectroscopic observations of the nebula around the luminous blue variable (LBV) star AG Car have been obtained along with optical imaging in the Halpha+[NII] filter. In the infrared light, the nebula appears as a clumpy ring shell that extends up to 1.2 pc with an inner radius of 0.4 pc. It coincides with the Halpha nebula, but extends further out. Dust modeling of the nebula was performed and indicates the presence of large grains. The dust mass is estimated to be ~ 0.2 Msun. The infrared spectrum of the nebula consists of forbidden emission lines over a dust continuum. Apart from ionized gas, these lines also indicate the existence of neutral gas in a photodissociation region that surrounds the ionized region. The abundance ratios point towards enrichment by processed material. The total mass of the nebula ejected from the central star amounts to ~ 15 Msun, assuming a dust-to-gas ratio typical of LBVs. The abundances and the mass-loss rate were used to constrain the evolutionary path of the central star and the epoch at which the nebula was ejected, with the help of available evolutionary models. This suggests an ejection during a cool LBV phase for a star of ~ 55 Msun with little rotation.

arXiv commentaccepted for publication in A&A

References in corpus (29)

• Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy
• The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory
• The Herschel-SPIRE instrument and its in-flight performance
• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• Mass Loss: Its Effect on the Evolution and Fate of High-Mass Stars
• The Infrared Astronomical Mission AKARI
• Far Infrared and Submillimeter Emission from Galactic and Extragalactic Photo-Dissociation Regions
• The AKARI/IRC Mid-Infrared All-Sky Survey
• Hi-GAL: the Herschel infrared Galactic Plane Survey
• Stellar evolution with rotation X: Wolf-Rayet star populations at solar metallicity
• The Discordance of Mass-Loss Estimates for Galactic O-Type Stars
• Scanamorphos: a map-making software for Herschel and similar scanning bolometer arrays
• Low mass loss rates in O-type stars: Spectral signatures of dense clumps in the wind of two Galactic O4 stars
• Rapid formation of large dust grains in the luminous supernova SN 2010jl
• The evolution of massive stars and their spectra I. A non-rotating 60 Msun star from the zero-age main sequence to the pre-supernova stage
• MESS (Mass-loss of Evolved StarS), a Herschel Key Program
• A deep survey of heavy element lines in planetary nebulae - I. Observations and forbidden-line densities, temperatures and abundances
• On the nature of the prototype LBV AG Carinae I. Fundamental parameters during visual minimum phases and changes in the bolometric luminosity during the S-Dor cycle
• Chemical composition and origin of nebulae around Luminous Blue Variables
• 2-Dust : a Dust Radiative Transfer Code for an Axisymmetric System
• The Astrophysical Implications of Dust Formation During The Eruptions of Hot, Massive Stars
• Two Subclasses of Proto-Planetary Nebulae: Model Calculations
• On the nature of the prototype LBV AG Carinae II. Witnessing a massive star evolving close to the Eddington and bistability limits
• The dusty Nebula surrounding HR Car: a Spitzer view
• Multiple shells around G79.29+0.46 revealed from near-IR to millimeter data
• Herschel imaging and spectroscopy of the nebula around the luminous blue variable star WRAY 15-751
• Detection of CO emission 12 CO J=1->0 and 12 CO J=2->1 from the Luminous Blue Variable Star AG Carinae: circumstellar envelope or disk?
• A massive parsec-scale dust ring nebula around the yellow hypergiant Hen3-1379
• Dust Formation in the Presence of Photons I: Evaporation Rates for Small Dust Grains

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• Luminous Blue Variables
• The contribution by luminous blue variable stars to the dust content of the Magellanic Clouds
• A warm molecular ring in AG Car: composing the mass-loss puzzle
• MeerKAT reveals a ghostly thermal radio ring towards the Galactic Centre
• Millimetre continuum from LBV stars and their environs. NIKA2 observations and Virtual Observatory data