Unraveling the Nature of the Deeply Embedded Wolf–Rayet Star WR 121a

Arora, Bharti; Pandey, J. C.

doi:10.3847/1538-4357/ab7337

Cited by 4 publications

(2 citation statements)

References 58 publications

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“…As a result, even though the low state is likely related to periastron, the exact time of periastron passage cannot be determined with accuracy, given the available information on the system. We also clarify that in such a long period system, we can certainly reject the hypothesis of an eclipse of the CWR by one of the stars as observed in the short period massive binary WR 121a (Arora & Pandey 2020).…”

Section: X-ray Emissionsupporting

confidence: 58%

Quest for the upcoming periastron passage of an episodic dust maker and particle accelerating colliding wind binary: WR 125

Arora,

Pandey,

De Becker

et al. 2021

Preprint

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We have carried out a long term infrared and X-ray investigation of the colliding wind binary WR 125 (WC7 + O9III). The source was monitored using AstroSat−Soft X-ray Telescope and TIRCAM2 mounted at the back of 3.6 m Devasthal Optical Telescope. WR 125 appeared brighter in near infra-red K-band during the years 2017-2021 which is attributed to another episode of dust formation similar to the one reported during the likely periastron passage at the beginning of the 1990s. This is further supported by enhanced emission observed in W1 and W2 bands of WISE from 2018-19. By combining archival X-ray data sets with our new measurements, long-term variations have been noticed. The source reaches a lower emission state in June 2020 (close to the recent infrared maximum) which could be due to enhanced absorption of X-rays produced in the colliding wind region by the WC stellar wind close to the periastron in an eccentric orbit. The time interval between the previous and latest X-ray low states may indicate an orbital period of 28-29 years, in fair agreement with the recurrence time of episodic dust production. We also discuss published radio measurements in the context of a common picture based on a long period binary scenario. These results allow us to draw relevant guidelines for future multi-wavelength observations of WR 125.

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Section: X-ray Emissionsupporting

confidence: 58%

Quest for the upcoming periastron passage of an episodic dust maker and particle accelerating colliding wind binary: WR 125

Arora,

Pandey,

De Becker

et al. 2021

Preprint

Self Cite

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show abstract

“…X-ray observations have been made of all three systems (Gosset et al (2009), Skinner et al (2010), Raassen et al (2003), Pollock & Corcoran (2006)) and are summarised in Table C1. WR22 and WR25 have already been confirmed as binaries via RV studies, and both sources also appear to show orbitally modulated X-ray fluxes (Gosset et al (2009), Arora et al (2020)). WR22 is of particularly interest since it is observed to be particularly faint at the point at which the WNLha and associated wind might be expected to eclipse both the secondary and any associated wind interaction zone (𝐿 X ∼ 6.3 × 10 31 erg −1 ).…”

Section: Data Availabilitymentioning

confidence: 90%

The Arches cluster revisited: IV. Observational constraints on the binary properties of very massive stars

Clark¹,

Lohr²,

Najarro³

et al. 2023

Preprint

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Serving as the progenitors of electromagnetic and gravitational wave transients, massive stars have received renewed interest in recent years. However, many aspects of their birth and evolution remain opaque, particularly in the context of binary interactions. The centre of our galaxy hosts a rich cohort of very massive stars, which appear to play a prominent role in the ecology of the region. In this paper we investigate the binary properties of the Arches cluster, which is thought to host a large number of very massive stars. A combination of multi-epoch near-IR spectroscopy and photometry was utilised to identify binaries. 13 from 36 cluster members meet our criteria to be classed as RV variable. Combining the spectroscopic data with archival radio and X-ray observations -to detect colliding wind systems -provides a lower limit to the binary fraction of ∼ 43%; increasing to 50% for the O-type hypergiants and WNLha. Dynamical and evolutionary masses reveal the primaries to be uniformly massive ( 50𝑀 ). Where available, orbital analysis reveals a number of short period, highly eccentric binaries, which appear to be pre-interaction systems. Such systems are X-ray luminous, with 80% above an empirical bound of (𝐿 x /𝐿 bol ) ∼ 10 −7 and their orbital configurations suggest formation and evolution via a single star channel; however, we cannot exclude a binary formation channel for a subset. Qualitative comparison to surveys of lower mass OB-type stars confirms that the trend to an extreme binary fraction (≥ 60%) extends to the most massive stars currently forming in the local Universe.

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The Arches cluster revisited – IV. Observational constraints on the binary properties of very massive stars

Clark

Lohr

Najarro

et al. 2023

Monthly Notices of the Royal Astronomical Society

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Serving as the progenitors of electromagnetic and gravitational wave transients, massive stars have received renewed interest in recent years. However, many aspects of their birth and evolution remain opaque, particularly in the context of binary interactions. The centre of our galaxy hosts a rich cohort of very massive stars, which appear to play a prominent role in the ecology of the region. In this paper we investigate the binary properties of the Arches cluster, which is thought to host a large number of very massive stars. A combination of multi-epoch near-IR spectroscopy and photometry was utilised to identify binaries. 13 from 36 cluster members meet our criteria to be classed as RV variable. Combining the spectroscopic data with archival radio and X-ray observations - to detect colliding wind systems - provides a lower limit to the binary fraction of ∼43%; increasing to ≳ 50% for the O-type hypergiants and WNLha. Dynamical and evolutionary masses reveal the primaries to be uniformly massive (≳ 50M⊙). Where available, orbital analysis reveals a number of short period, highly eccentric binaries, which appear to be pre-interaction systems. Such systems are X-ray luminous, with 80% above an empirical bound of (Lx/Lbol) ∼ 10−7 and their orbital configurations suggest formation and evolution via a single star channel; however, we cannot exclude a binary formation channel for a subset. Qualitative comparison to surveys of lower mass OB-type stars confirms that the trend to an extreme binary fraction (≥60%) extends to the most massive stars currently forming in the local Universe.

show abstract

Unraveling the Nature of the Deeply Embedded Wolf–Rayet Star WR 121a

Cited by 4 publications

References 58 publications

Quest for the upcoming periastron passage of an episodic dust maker and particle accelerating colliding wind binary: WR 125

Quest for the upcoming periastron passage of an episodic dust maker and particle accelerating colliding wind binary: WR 125

The Arches cluster revisited: IV. Observational constraints on the binary properties of very massive stars

The Arches cluster revisited – IV. Observational constraints on the binary properties of very massive stars

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