Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System

Abstract

AQ Col (EC 05217-3914) is one of the first detected pulsating subdwarf B (sdB) stars and has been considered to be a single star. Photometric monitoring of AQ Col reveals a pulsation timing variation with a period of 486 days, interpreted as time-delay due to reflex motion in a wide-binary formed with an unseen companion with expected mass larger than 1.05 $M_{\odot }$. The optical spectra and color-Magnitude diagram of the system suggested that the companion is not a main sequence star but a white dwarf or neutron star. The pulsation timing variation also shows that the system has an eccentricity of 0.424, which is much larger than any known sdB long period binary system. That might be due to the existence of another short period companion to the sdB star. Two optical spectra obtained on 1996 December $5^{\mathrm{th}}$ show a radial velocity change of 49.1~km/s in 46.1 minutes, which suggests the hot subdwarf in the wide-binary is itself a close-binary formed with another unseen white dwarf or neutron star companion; if further observations show this interpretation to be correct, AQ Col is an interesting triple system worthy of further study.

accepted to ApJ. 26 pages, 10 figures

References in corpus (29)

• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Achieving better than 1 minute accuracy in the Heliocentric and Barycentric Julian Dates
• Gaia Early Data Release 3: Photometric content and validation
• Pulsating White Dwarf Stars and Precision Asteroseismology
• Barycentric Corrections at 1 cm/s for precise Doppler velocities
• The evolution of stellar triples: The most common evolutionary pathways
• Hot subdwarf binaries from the MUCHFUSS project - Analysis of 12 new systems and a study of the short-period binary population
• Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binaries
• Finding binaries among Kepler pulsating stars from phase modulation of their pulsations
• A hot subdwarf-white dwarf super-Chandrasekhar candidate supernova Ia progenitor
• Composite hot-subdwarf binaries -- I. The spectroscopically confirmed sdB sample
• Observed binary populations reflect the Galactic history. Explaining the orbital period-mass ratio relation in wide hot subdwarf binaries
• The Remote Observatories of the Southeastern Association for Research in Astronomy (SARA)
• Deriving the orbital properties of pulsators in binary systems through their light arrival time delays
• KIC7668647: a 14 day beaming sdB+WD binary with a pulsating subdwarf
• Subdwarf B stars from the common envelope ejection channel
• The temporal changes of the pulsational periods of the pre-white dwarf PG 1159-035
• Validation of the Frequency Modulation technique applied to the pulsating delta Sct - gamma Dor eclipsing binary star KIC 8569819
• Finding binaries from phase modulation of pulsating stars with Kepler. IV. Detection limits and radial velocity verification
• TESS first look at evolved compact pulsators: Known ZZ Ceti stars of the southern ecliptic hemisphere as seen by TESS
• Whole Earth Telescope observations of the hot helium atmosphere pulsating white dwarf EC 20058-5234
• Metal-Rich SX Phe stars in the Kepler Field
• The pulsating white dwarf G117-B15A: still the most stable optical clock known
• Orbital and atmospheric parameters of two wide O-type subdwarf binaries: BD$-$11${}^{\mathrm{o}}$162 and Feige 80
• Hot subdwarf B stars with neutron star components II: Binary population synthesis
• A binary with a $\delta$~Scuti star and an oscillating red giant: orbit and asteroseismology of KIC9773821
• EPIC 216747137: a new HW Vir eclipsing binary with a massive sdOB primary and a low-mass M-dwarf companion
• Spectroscopic confirmation of the binary nature of the hybrid pulsator KIC 5709664 found with the frequency modulation method
• The EXOTIME project: Signals in the $O-C$ diagrams of the rapidly pulsating subdwarfs DW Lyn, V1636 Ori, QQ Vir, and V541 Hya

Cited by in corpus (2)

• The first massive compact companion in a wide orbit around a hot subdwarf star
• Volume-limited sample of low-mass red giant stars, the progenitors of hot subdwarf stars I. Sample selection and binary classification method