An accreting dwarf star orbiting the S-type giant star pi1 Gru

Abstract

Aims. We aim to characterize the properties of the inner companion of the S-type AGB star pi1 Gru and to identify plausible future evolutionary scenarios for this triple system. Methods. We observed pi1 Gru with ALMA and VLT/SPHERE. In addition, we collected archival photometry data and used the Hipparcos-Gaia proper motion anomaly. We derive the best orbital parameters from Bayesian inference. Results. In June-July 2019, the inner companion, pi1 Gru C, was located at 37.4 +/- 2.0 mas from the primary (a projected separation of 6.05 +/- 0.55 au at 161.7 +/- 11.7 pc). The best orbital solution yields a companion mass of 0.86 (+0.22/-0.20) Msun (using the derived mass of the primary) and a semi-major axis of 7.05(+0.54/-0.57) au, corresponding to an orbital period of 11.0 (+1.7/-1.5) yr. The preferred solution is an elliptical orbit with eccentricity e = 0.35(+0.18/-0.17), although a circular orbit cannot be fully excluded. The close companion could be either a K1V (F9.5V to K7V) star or a white dwarf (WD). Ultraviolet and millimeter continuum photometry are consistent with the presence of an accretion disk around the close companion. The ultraviolet emission may originate from hot spots in an overall cooler disk, or from a hot disk if the companion is a WD. Conclusions. Although the close companion and the AGB star are interacting and an accretion disk is observed around the companion, the mass-accretion rate is too low to trigger a Type Ia supernova, but it could produce novae every ~900 yr. Short-wavelength, spatially resolved observations are required to further constrain the nature of the C companion. Searches for close-in companions similar to this system will improve our understanding of the physics of mass and angular momentum transfer, as well as orbital evolution during late evolutionary stages.

arXiv commentAccepted for publications in Astronomy & Astrophysics. 21 pages, 10+2 figures, 3+4 tables. v2: Language and formatting editing. Correction in inclination convention

References in corpus (79)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• The Gaia mission
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Gaia Data Release 3: Summary of the content and survey properties
• Validation of the new Hipparcos reduction
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• SPHERE: the exoplanet imager for the Very Large Telescope
• The Second-Generation Guide Star Catalog: Description and Properties
• Revised Catalog of GALEX Ultraviolet Sources. I. The All-sky Survey: GUVcat_AIS
• New models for the evolution of Post-Asymptotic Giant Branch stars and Central Stars of Planetary Nebulae
• Post-Asymptotic Giant Branch Evolution of Low- and Intermediate-Mass Stars. Preliminary Results
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• The White Dwarf Initial-Final Mass Relation for Progenitor Stars From 0.85 to 7.5 M${}_{\odot }$
• Introduction to astroML: Machine Learning for Astrophysics
• Periodograms for Multiband Astronomical Time Series
• Stellar and substellar companions from Gaia EDR3 -- Proper motion anomaly and resolved common proper motion pairs
• Probing the mass-loss history of AGB and red supergiant stars from CO rotational line profiles - II. CO line survey of evolved stars: derivation of mass-loss rate formulae
• A statistical test for Nested Sampling algorithms
• Evidence for the White Dwarf Nature of Mira B
• Collaborative Nested Sampling: Big Data vs. complex physical models
• Resolving the stellar activity of the Mira AB binary with ALMA
• Unexpectedly large mass loss during the thermal pulse cycle of the red giant R Sculptoris!
• Recurrent novae as a progenitor system of Type Ia supernovae. I. RS Ophiuchi subclass --- Systems with a red giant companion
• The impact of companions on stellar evolution
• SPHERE / ZIMPOL high resolution polarimetric imager. I. System overview, PSF parameters, coronagraphy, and polarimetry
• The Southern Proper Motion Program IV. The SPM4 Catalog
• MESS (Mass-loss of Evolved StarS), a Herschel Key Program
• (Sub)stellar companions shape the winds of evolved stars
• Interferometric observations of the supergiant stars alpha Orionis and alpha Herculis with FLUOR at IOTA
• Orbital properties of binary post-AGB stars
• ALMA observations of the nearby AGB star L2 Puppis - I. Mass of the central star and detection of a candidate planet
• Mid-infrared interferometry on spectral lines: III. Ammonia and Silane around IRC+10216 and VY CMa
• Calibrated griz magnitudes of Tycho stars: All-sky photometric calibration using bright stars
• Interferometric observations of the Mira star o Ceti with the VLTI/VINCI instrument in the near-infrared
• Evolution and Mass Loss of Cool Ageing Stars: a Daedalean Story
• J, H, K spectro-interferometry of the Mira variable S Orionis
• SPHERE / ZIMPOL observations of the symbiotic system R Aqr. I. Imaging of the stellar binary and the innermost jet clouds
• A Catalog of GALEX Ultraviolet Emission from Asymptotic Giant Branch Stars
• Mid-infrared interferometry on spectral lines: II. Continuum (dust) emission around IRC+10216 and VY CMa
• Circumstellar shells and mass loss rates: Clues to the evolution of S stars
• The light curve of the semiregular variable L2 Puppis: I. A recent dimming event from dust
• Star-galaxy separation by far-infrared color-color diagrams for the AKARI FIS All-Sky Survey (Bright Source Catalogue Version beta-1)
• Aperture synthesis imaging of the carbon AGB star R Sculptoris: Detection of a complex structure and a dominating spot on the stellar disk
• The extended molecular envelope of the asymptotic giant branch star ${\pi }^1$ Gruis as seen by ALMA I. Large-scale kinematic structure and CO excitation properties
• ATOMIUM: ALMA tracing the origins of molecules in dust forming oxygen rich M-type stars: Motivation, sample, calibration, and initial results
• Long-term photometry and periods for 261 nearby pulsating M giants
• An all-sky catalog of solar-type dwarfs for exoplanetary transit surveys
• The impact of stellar companion UV photons on the chemistry of the circumstellar environments of AGB stars
• SPH modelling of companion-perturbed AGB outflows including a new morphology classification scheme
• Atomium: A high-resolution view on the highly asymmetric wind of the AGB star Pi1 Gruis. I. First detection of a new companion and its effect on the inner wind
• Temporal variations of the outer atmosphere and the dust shell of the carbon-rich Mira variable V Oph probed with VLTI/MIDI
• Binary evolution along the Red Giant Branch with BINSTAR: The barium star perspective
• High-resolution observations of the symbiotic system R Aqr. Direct imaging of the gravitational effects of the secondary on the stellar wind
• The VLTI/MIDI view on the inner mass loss of evolved stars from the Herschel MESS sample
• ATOMIUM: Molecular inventory of 17 oxygen-rich evolved stars observed with ALMA
• Interplay between pulsation, mass loss, and third dredge-up: More about Miras with and without technetium
• Discovery of the first resolved triple white dwarf
• The extended molecular envelope of the asymptotic giant branch star ${\pi }^1$ Gruis as seen by ALMA II. The spiral-outflow observed at high-angular resolution
• The close circumstellar environment of the semi-regular S-type star Pi^1 Gruis
• CO envelope of the symbiotic star R Aqr seen by ALMA
• The radio continuum spectrum of Mira A and Mira B up to submillimeter wavelengths
• The VLT/SPHERE view of the ATOMIUM cool evolved star sample. I. Overview: Sample characterization through polarization analysis
• A statistical search for Star-Planet Interaction in the UltraViolet using GALEX
• Structure and dynamics of the inner nebula around the symbiotic stellar system R Aqr
• The surprisingly carbon-rich environment of the S-type star W Aql
• Impact of HI cooling and study of accretion disks in AGB wind-companion smoothed particle hydrodynamic simulations
• Chemical tracers of a highly eccentric AGB-main sequence star binary
• Classifying the secondary component of the binary star W Aquilae
• The Red Giant Branch in the Tycho-2 Catalogue
• AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L2 Pup
• NSCC -- A New Scheme of Classification of C-rich Stars Devised from Optical and Infrared Observations
• Geometrical model fitting for interferometric data: GEM-FIND
• Flickering in AGB stars: Probing the nature of accreting companions
• A dynamic view of V Hydrae. Monitoring of a spectroscopic-binary AGB star with an alkaline jet
• An impressionist view of V Hydrae. When MATISSE paints Asymmetric Giant Blobs

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