A candidate magnetic helium core white dwarf in the globular cluster NGC 6397
arXiv:2303.04184 · doi:10.1093/mnras/stad722
Abstract
We report a peculiar variable blue star in the globular cluster NGC 6397, using Hubble Space Telescope optical imaging. Its position in the colour-magnitude diagrams, and its spectrum, are consistent with this star being a helium core white dwarf (He WD) in a binary system. The optical light curve shows a periodicity at 18.5 hours. We argue that this periodicity is due to the rotation of the WD and possibly due to magnetic spots on the surface of the WD. This would make this object the first candidate magnetic He WD in any globular cluster (GC), and the first candidate magnetic WD in a detached binary system in any GC and one of the few He WDs with a known rotation period and of magnetic nature. Another possibility is that this system is a He WD in a binary system with another WD or another degenerate object, which would make this object one of the few candidate non-accreting double degenerate binaries in any GC.
arXiv commentAccepted for publication in MNRAS
References in corpus (39)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- Astropy: A Community Python Package for Astronomy
- The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
- Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
- WFPC2 Stellar Photometry with HSTphot
- Resolved Massive Star Clusters in the Milky Way and its Satellites: Brightness Profiles and a Catalogue of Fundamental Parameters
- The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. I. Overview of the Project and Detection of Multiple Stellar Populations
- Assessing statistical significance of periodogram peaks
- Accurate distances to Galactic globular clusters through a combination of Gaia EDR3, HST and literature data
- Magnetic White Dwarfs
- New evolutionary sequences for extremely low mass white dwarfs: Homogeneous mass and age determinations, and asteroseismic prospects
- The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters - XVII. Public Catalogue Release
- The White Dwarf Cooling Sequence of NGC6397
- Observations of Doppler Boosting in Kepler Lightcurves
- MUSE crowded field 3D spectroscopy of over 12,000 stars in the globular cluster NGC 6397 - I. The first comprehensive spectroscopic HRD of a globular cluster
- The chemical composition of donors in AM CVn stars and ultra-compact X-ray binaries: observational tests of their formation
- The ELM Survey. VIII. 98 Double White Dwarf Binaries
- On type Ia supernovae and the formation of single low-mass white dwarfs
- Optical spectroscopy of (candidate) ultra-compact X-ray binaries: constraints on the composition of the donor stars
- Deep ACS Imaging in the Globular Cluster NGC 6397: The Cluster Color Magnitude Diagram and Luminosity Function
- The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXIII. Proper-motion catalogs and internal kinematics
- Probing the Faintest Stars in a Globular Star Cluster
- MUSE crowded field 3D spectroscopy of over 12,000 stars in the globular cluster NGC 6397 - II. Probing the internal dynamics and the presence of a central black hole
- Cataclysmic Variables and a New Class of Faint UV Stars in the Globular Cluster NGC 6397
- A Chandra X-ray Observatory Study of PSR J1740--5340 and Candidate Millisecond Pulsars in the Globular Cluster NGC 6397
- The Binary Fraction of Low Mass White Dwarfs
- Cataclysmic Variables and a Candidate Helium White Dwarf in the Globular Cluster NGC 6397
- White Dwarf Subsystems in Core-Collapsed Globular Clusters
- Helium-Core White Dwarfs in the Globular Cluster NGC 6397
- Evolution and colors of helium-core white dwarf stars with high-metallicity progenitors
- X-ray Census of Millisecond Pulsars in the Galactic field
- Outer boundary conditions for evolving cool white dwarfs
- FAST discovery of an extremely radio-faint millisecond pulsar from the Fermi-LAT unassociated source 3FGL J0318.1+0252
- The MAVERIC Survey: Chandra/ACIS Catalog of Faint X-ray sources in 38 Galactic globular clusters
- A Census of X-ray Millisecond Pulsars in Globular Clusters
- The origin of single low-mass WDs: another problem that consequential angular momentum loss in CVs might solve
- Discovery of near-ultraviolet counterparts to millisecond pulsars in the globular cluster 47 Tucanae
- Radio detection of an elusive millisecond pulsar in the Globular Cluster NGC 6397
- The MAVERIC survey: A catalogue of radio sources in southern globular clusters from the Australia Telescope Compact Array