2021/03/06 by Manuel Pichardo Marcano, L. E. Rivera Sandoval, Thomas J. Maccarone +3 · 7 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Globular cluster #Millisecond pulsar #Orbital period #Physics #Pulsar #Pulsars and Gravitational Waves Research #Star cluster #Stars #Stellar, planetary, and galactic studies #astro-ph.HE
paper · pdf · doi:10.1093/mnrasl/slab024
published in Monthly Notices of the Royal Astronomical Society Letters 503(1), L51-L55 (Oxford University Press) · Accepted for publication as a letter in MNRAS
arxiv created 2021/03/06 · openalex publication_date 2021/03/09 · openalex created_date 2021/03/15 · arxiv updated 2021/08/04 · openalex updated_date 2026/08/05
ABSTRACT We report optical modulation of the companion to the X-ray source U18 in the globular cluster NGC 6397. U18, with combined evidence from radio and X-ray measurements, is a strong candidate as the second redback in this cluster, initially missed in pulsar searches. This object is a bright variable star with an anomalous red colour and optical variability (∼0.2 mag in amplitude) with a periodicity ∼1.96 d that can be interpreted as the orbital period. This value corresponds to the longest orbital period for known redback candidates and confirmed systems in Galactic globular clusters and one of the few with a period longer than 1 d.