Discovery of magnetic A supergiants: the descendants of magnetic main sequence B stars

Abstract

In the context of the high resolution, high signal-to-noise ratio, high sensitivity, spectropolarimetric survey BritePol, which complements observations by the BRITE constellation of nanosatellites for asteroseismology, we are looking for and measuring the magnetic field of all stars brighter than V=4. In this paper, we present circularly polarised spectra obtained with HarpsPol at ESO in La Silla (Chile) and ESPaDOnS at CFHT (Hawaii) for 3 hot evolved stars: $\iota$ Car, HR 3890, and $\epsilon$ CMa. We detected a magnetic field in all 3 stars. Each star has been observed several times to confirm the magnetic detections and check for variability. The stellar parameters of the 3 objects were determined and their evolutionary status was ascertained employing evolution models computed with the Geneva code. $\epsilon$ CMa was already known and is confirmed to be magnetic, but our modeling indicates that it is located near the end of the main sequence, i.e. it is still in a core hydrogen burning phase. $\iota$ Car and HR 3890 are the first discoveries of magnetic hot supergiants located well after the end of the main sequence on the HR diagram. These stars are probably the descendants of main sequence magnetic massive stars. Their current field strength (a few G) is compatible with magnetic flux conservation during stellar evolution. These results provide observational constraints for the development of future evolutionary models of hot stars including a fossil magnetic field.

arXiv comment11 pages, 5 figures, 3 tables, in press in MNRAS

References in corpus (50)

• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• Pre-Supernova Evolution of Massive Single and Binary Stars
• Presupernova Evolution of Differentially Rotating Massive Stars Including Magnetic Fields
• Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models
• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: I. Isothermal, Nonrotating, Radially Driven Flow
• Stable magnetic fields in stellar interiors
• On magnetic instabilities and dynamo action in stellar radiation zones
• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: II. The Effects of Field-Aligned Rotation
• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: III. Angular Momentum Loss and Rotational Spindown
• The MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type stars
• BRITE-Constellation: nanosatellites for precision photometry of bright stars
• Simulations of core convection in rotating A-type stars: Magnetic dynamo action
• The spectroscopic Hertzsprung-Russell diagram
• Searching for links between magnetic fields and stellar evolution. II. The evolution of magnetic fields as revealed by observations of Ap stars in open clusters and associations
• 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
• The IACOB project: III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars
• Searching for links between magnetic fields and stellar evolution. I. A survey of magnetic fields in open cluster A- and B-type stars with FORS1
• Transport and mixing in the radiation zones of rotating stars II. Axisymmetric magnetic field
• Quantitative Spectroscopy of BA-type Supergiants
• Searching for links between magnetic fields and stellar evolution III. Measurement of magnetic fields in open cluster Ap stars with ESPaDOnS
• Non-LTE line-formation for hydrogen revisited
• Massive star models with magnetic braking
• Populations of rotating stars. - I. Models from 1.7 to 15 Msun at Z = 0.014, 0.006, and 0.002 with Ω/Ωcrit between 0 and 1
• Stellar evolution with rotation and magnetic fields:I. The relative importance of rotational and magnetic effects
• Magnetic Fields in Massive Stars. II. The Buoyant Rise of Magnetic Flux Tubes Through the Radiative Interior
• B fields in OB stars (BOB): low-resolution FORS2 spectropolarimetry of the first sample of 50 massive stars
• Magnetic massive stars as progenitors of "heavy" stellar-mass black holes
• The Magnetic Fields at the Surface of Active Single G-K Giants
• Discovery of Rotational Braking in the Magnetic Helium-Strong Star Sigma Orionis E
• The search for magnetic fields in mercury-manganese stars
• The weak magnetic field of the O9.7 supergiant zeta Orionis A
• Systematic detection of magnetic fields in massive, late-type supergiants
• Possible pair-instability supernovae at solar metallicity from magnetic stellar progenitors
• EK Eridani: the tip of the iceberg of giants which have evolved from magnetic Ap stars
• On magnetic inhibition of photospheric macro-turbulence generated in the iron-bump opacity zone of O-stars
• A high-resolution spectropolarimetric survey of Herbig Ae/Be stars - II. Rotation
• Effect of a fossil magnetic field on the structure of a young Sun
• Evidence of magnetic field decay in massive main-sequence stars
• Spectroscopic evolution of massive stars on the main sequence
• Quantitative spectroscopy of Galactic BA-type supergiants. I. Atmospheric parameters
• Magnetic braking of stellar cores in red giants and supergiants
• The magnetic field of zeta Orionis A
• Dynamical mass of the O-type supergiant in Zeta Orionis A
• B fields in OB stars (BOB): on the detection of weak magnetic fields in the two early B-type stars beta CMa and epsilon CMa
• Blue supergiants as descendants of magnetic main sequence stars
• CNO in evolved intermediate mass stars
• The dramatic change of the fossil magnetic field of HD 190073: evidence of the birth of the convective core in a Herbig star ?
• An Observational Evaluation of Magnetic Confinement in the Winds of BA Supergiants
• Abundance analysis of the supergiant stars HD 80057 and HD 80404 based on their UVES Spectra
• Dynamo Scaling Relationships

Cited by in corpus (18)

• The Magnetic Early B-type Stars III: A main sequence magnetic, rotational, and magnetospheric biography
• The Magnetic Early B-type Stars I: Magnetometry and Rotation
• The effects of surface fossil magnetic fields on massive star evolution: I. Magnetic field evolution, mass-loss quenching and magnetic braking
• The effects of surface fossil magnetic fields on massive star evolution: II. Implementation of magnetic braking in MESA and implications for the evolution of surface rotation in OB stars
• A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the Main Sequence to planets
• New mass-loss rates of B supergiants from global wind models
• First results from the LIFE project: discovery of two magnetic hot evolved stars
• The effects of surface fossil magnetic fields on massive star evolution: IV. Grids of models at Solar, LMC, and SMC metallicities
• Testing the fossil field hypothesis: could strongly magnetised OB stars produce all known magnetars?
• Magnetism in High-Mass Stars
• A search for strong magnetic fields in massive and very massive stars in the Magellanic Clouds
• NGC 6611 601: A hot pre-main sequence spectroscopic binary containing a centrifugal magnetosphere host star
• B stars seen at high resolution by XMM-Newton
• Ultraviolet Spectropolarimetric Diagnostics of Hot Star Magnetospheres
• Yellow hypergiant V509 Cas -- stable in the 'yellow void'
• Evolution of random initial magnetic fields in stably stratified and barotropic stars
• Stellar Magnetism
• CoronaGraph Instrument Reference stars for Exoplanets (CorGI-REx) I. Preliminary Vetting and Implications for the Roman Coronagraph and Habitable Worlds Observatory