A Millisecond Pulsar Optical Counterpart with Large-Amplitude Variability in the Globular Cluster 47 Tucanae

Abstract

Using extensive HST imaging, combined with Chandra X-ray and Parkes radio data, we have detected the optical binary companion to a second millisecond pulsar (MSP) in the globular cluster 47 Tucanae. This faint (V=22.3) blue (V-I=0.7) star shows a large amplitude (60-70%) sinusoidal variation in both V and I. The period (3.19066 hr) and phase of the variation match those of the MSP 47 Tuc W (which does not have an accurate radio timing position) to within 0.5 seconds and 1.2 minutes respectively, well within the ~1sigma errors. The phase dependence of the intensity and color implies that heating of a tidally locked companion causes the observed variations. The eclipsing nature of this MSP in the radio, combined with the relatively large companion mass (> 0.13 solar masses) and the companion's position in the color-magnitude diagram, suggest that the companion is a main sequence star, a rare circumstance for an MSP companion. This system is likely to have had a complex evolution and represents an interesting case study in MSP irradiation of a close companion. We present evidence for another optical variable with similar properties to the companion of 47 Tuc W. This variable may also be an MSP companion, although no radio counterpart has yet been detected.

11 pages, 9 figures, accepted for publication in ApJ

References in corpus (19)

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Cited by in corpus (45)

• A Deep Chandra Survey of the Globular Cluster 47 Tucanae: Catalog of Point Sources
• Eight New Millisecond Pulsars in NGC 6440 and NGC 6441
• Analysis of the Quiescent Low-Mass X-ray Binary Population in Galactic Globular Clusters
• Chandra X-Ray Observations of Nineteen Millisecond Pulsars in the Globular Cluster 47 Tucanae
• Long-term observations of the pulsars in 47 Tucanae - II. Proper motions, accelerations and jerks
• Chandra Study of a Complete Sample of Millisecond Pulsars in 47Tuc and NGC6397
• An Extensive Census of HST Counterparts to Chandra X-ray Sources in the Globular Cluster 47 Tucanae. I. Astrometry and Photometry
• An X-ray Variable Millisecond Pulsar in the Globular Cluster 47 Tucanae: Closing the Link to Low Mass X-ray Binaries
• An Extensive Census of HST Counterparts to Chandra X-ray Sources in the Globular Cluster 47 Tucanae. II. Time Series and Analysis
• Long-term observations of the pulsars in 47 Tucanae. I. A study of four elusive binary systems
• PSR J1723-2837: An Eclipsing Binary Radio Millisecond Pulsar
• A Chandra X-ray Observatory Study of PSR J1740--5340 and Candidate Millisecond Pulsars in the Globular Cluster NGC 6397
• GMRT Discovery of A Millisecond Pulsar in a Very Eccentric Binary System
• Chandra X-ray Observations of 12 Millisecond Pulsars in the Globular Cluster M28
• Three Binary Millisecond Pulsars in NGC 6266
• GBT Discovery of Two Binary Millisecond Pulsars in the Globular Cluster M30
• The Helium White Dwarf orbiting the Millisecond Pulsar in the halo of the Globular Cluster NGC 6752
• New Cataclysmic Variables and other Exotic Binaries in the Globular Cluster 47 Tucanae
• The optical companion to the binary millisecond pulsar J1824-2452H in the globular cluster M28
• Chandra studies of the globular cluster 47 Tucanae: A deeper X-ray source catalogue, five new X-ray counterparts to millisecond radio pulsars, and new constraints to r-mode instability window
• Radio timing and optical photometry of the black widow system PSR J1518+0204C in the globular cluster M5
• Accurate mass ratio and heating effects in the dual-line millisecond binary pulsar in NGC 6397
• Optical Identification of He White Dwarfs Orbiting Four Millisecond Pulsars in the Globular Cluster 47 Tucanae
• The Optical Counterpart to the Accreting Millisecond X-ray Pulsar SAX J1748.9-2021 in the Globular Cluster NGC 6440
• The puzzling properties of the Helium White Dwarf orbiting the millisecond pulsar PSR J1911-5958A in NGC 6752
• Optical identification of the companion to PSR J1911-5958A, the pulsar binary in the outskirts of NGC 6752
• Radio Timing and Optical Photometry of the Black Widow System PSR J1953+1846A in the Globular Cluster M71
• Discovery of near-ultraviolet counterparts to millisecond pulsars in the globular cluster 47 Tucanae
• Variability of Nineteen Millisecond Pulsars in 47 Tucanae with CHANDRA/HRC-S
• Formation of redbacks via accretion induced collapse
• The Pulsar Population in Globular Clusters and in the Galaxy
• The identification of the optical companion to the binary millisecond pulsar J0610-2100 in the Galactic field
• The chemical composition of the peculiar companion to the millisecond pulsar in NGC 6397
• Photometric Binaries in 14 Magellanic Cloud Star Clusters
• Green Bank Telescope Discovery of the Redback Binary Millisecond Pulsar PSR J0212+5321
• Periodic X-ray sources in the Massive Globular Cluster 47 Tucanae: Evidence for Dynamically Formed Cataclysmic Variables
• On the vanishing orbital X-ray variability of the eclipsing binary millisecond pulsar 47 Tuc W
• Modeling Gas Evacuation Mechanisms in Present-Day Globular Clusters: Stellar Winds from Evolved Stars and Pulsar Heating
• Evolution of redback radio pulsars in globular clusters
• A New Pulsar in Green Bank Telescope Searches of Ten Globular Clusters
• Mining the time axis with TRON. I. Millisecond pulsars in Omega Centauri, Terzan 5 and 47 Tucanae detected through MeerKAT interferometric imaging
• Searching for exotic object companions in the dense core of NGC 362: a multi-wavelength and multi-epoch photometric analysis
• Identification and characterization of optical companions to the population of millisecond pulsars in the globular cluster M3
• A candidate to the long sought optical counterpart to the Rapid Burster in the bulge fossil fragment Liller 1
• PSR J0024$-$7204ai: a massive, eccentric binary system in the globular cluster 47 Tucanae