GG Carinae: discovery of orbital-phase-dependent 1.583-day periodicities in the B[e] supergiant binary

Porter, A.; Blundell, Katherine M.; Podsiadlowski, Philipp; Lee, Steven

doi:10.1093/mnras/stab817

Cited by 4 publications

(3 citation statements)

References 52 publications

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“…W232 is somewhat more X-ray luminous than expected for an isolated star (Clark et al 2008), suggesting a binary interpretation is appropriate, and we note that the sgB[e] binary GG Carinae also displays stable photometric and RV variability on a period of ∼1.53 days that is well below its ∼31 day orbital period (Porter et al 2021). GG Car has a significantly eccentric orbit, and these short period pulsations result from tidally-driven oscillations at the l = 2 f -mode frequency, with the largest variability occurring at periastron.…”

Section: The Peculiar B0 Iab Star W232mentioning

confidence: 67%

A VLT/FLAMES survey for massive binaries in Westerlund 1

Ritchie

Clark

Negueruela

et al. 2022

A&A

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Context. The galactic cluster Westerlund 1 contains a rich population of evolved, massive stars. A high binary fraction has been inferred from previous multi-wavelength observations. Aims. We use multi-epoch spectroscopy of a large sample of early-type stars in Westerlund 1 to identify new binaries and binary candidates in the cluster. Methods. VLT/FLAMES was used with the GIRAFFE spectrograph in HR21 mode to obtain spectra of ∼100 OB stars over a 14-month baseline in 2008 and 2009, supplemented with follow-up observations in 2011 and 2013. Radial velocities were obtained from strong Paschen series absorption lines in the I-band. Results. We identify 20 new OB I–III binaries, a WN9h binary, and a WC9d binary, greatly increasing the number of directly confirmed binary systems in Westerlund 1, while 12 O9−9.5 Iab−III stars are identified as candidate binaries based on radial velocity changes that are inconsistent with photospheric variability. The 173.9 day SB1 W1030 represents the first longer-period system identified in the cluster, while the determination of a 53.95 day period for W44 (WR L) makes it the first Wolf-Rayet binary in Westerlund 1 with a confirmed orbital period greater than ten days. Our results suggest the binary fraction in the OB population is at least ∼40%, and may be significantly higher. Conclusions. These results demonstrate that binary systems can be effectively identified in the population of OB I−III stars evolving off the main sequence in Westerlund 1. Future multi-epoch surveys will be able to fully characterise this population.

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Section: The Peculiar B0 Iab Star W232mentioning

confidence: 67%

A VLT/FLAMES survey for massive binaries in Westerlund 1

Ritchie

Clark

Negueruela

et al. 2022

A&A

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“…On the other hand, the B[e]SGs are considered more stable, with variability that does not exceed ∼0.2 mag (optical; [5]). However, this is changing and significant variability is observed, due to binary interactions and possible pulsations (e.g., [12,19,89]). Therefore, it is not surprising to observe similar magnitude differences between the two classes.…”

Section: Light Curves and Variabilitymentioning

confidence: 99%

Discovering New B[e] Supergiants and Candidate Luminous Blue Variables in Nearby Galaxies

Maravelias,

de Wit,

Bonanos

et al. 2023

Galaxies

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Mass loss is one of the key parameters that determine stellar evolution. Despite the progress we have achieved over the last decades we still cannot match the observational derived values with theoretical predictions. Even worse, there are certain phases, such as the B[e] supergiants (B[e]SGs) and the Luminous Blue Variables (LBVs), where significant mass is lost through episodic or outburst activity. This leads to various structures forming around them that permit dust formation, making these objects bright IR sources. The ASSESS project aims to determine the role of episodic mass in the evolution of massive stars, by examining large numbers of cool and hot objects (such as B[e]SGs/LBVs). For this purpose, we initiated a large observation campaign to obtain spectroscopic data for ∼1000 IR-selected sources in 27 nearby galaxies. Within this project we successfully identified seven B[e] supergiants (one candidate) and four Luminous Blue Variables of which six and two, respectively, are new discoveries. We used spectroscopic, photometric, and light curve information to better constrain the nature of the reported objects. We particularly noted the presence of B[e]SGs at metallicity environments as low as 0.14 Z⊙.

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“…Table 1 lists the known stellar parameters of GG Car and the binary separation and eccentricity. Porter et al (2021b) investigated the variability of the system over short timescales, and found a 1.583-day periodicity present in both photometry and spectroscopy whose amplitude is modulated by the orbital phase of the binary.…”

Section: Introductionmentioning

confidence: 99%

The circumbinary rings of GG Carinae: indications of disc eccentricity growth in the B[e] supergiant's atomic emission lines

Porter,

Blundell,

Lee

2021

Preprint

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B[e] supergiants have unusual circumstellar environments which may include thin, concentric rings displaying atomic line emission. GG Carinae is a B[e] supergiant binary which exhibits such a geometry in its circumbinary environment. We study atomic emission lines arising from GG Carinae's circumbinary disc in FEROS spectra collected between 1998 and 2015. We find that semi-forbidden Fe II] and permitted Ca II emission are formed in the same thin circumbinary ring previously reported to have forbidden [O I] and [Ca II] emission. We find that there are two circumbinary rings orbiting with projected velocities of 84.6 ± 1.0 km s −1 and 27.3 ± 0.6 km s −1 . Deprojecting these velocities from the line-of-sight, and using updated binary masses presented by Porter et al. (2021a), we find that the radii of the circumbinary rings are 2.8 +0.9 −1.1 AU and 27 +9 −10 AU for the inner ring and outer ring respectively. We find evidence of subtle dynamical change in the inner circumbinary ring over the 17 years spanned by the data, manifesting in variability in the ratio of the intensity of the blueshifted peak to the redshifted peak of its emission lines and the central velocity becoming more blueshifted. We perform smoothed-particle hydrodynamic simulations of the system which suggest that these observed changes are consistent with pumping of the eccentricity of a radially thin circumbinary ring by the inner binary. We find a systemic velocity of the GG Carinae system of −23.2 ± 0.4 km s −1 .

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GG Carinae: discovery of orbital-phase-dependent 1.583-day periodicities in the B[e] supergiant binary

Cited by 4 publications

References 52 publications

A VLT/FLAMES survey for massive binaries in Westerlund 1

A VLT/FLAMES survey for massive binaries in Westerlund 1

Discovering New B[e] Supergiants and Candidate Luminous Blue Variables in Nearby Galaxies

The circumbinary rings of GG Carinae: indications of disc eccentricity growth in the B[e] supergiant's atomic emission lines

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