GG Carinae: orbital parameters and accretion indicators from phase-resolved spectroscopy and photometry

Porter, A.; Grant, David; Blundell, Katherine M.; Lee, Steven

doi:10.1093/mnras/staa3749

Cited by 9 publications

(15 citation statements)

References 86 publications

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“…We find that the closer ring has a radius of 𝑅 = 2.8 +0.9 −1.1 AU from the binary, and the outer ring has 𝑅 = 27 +9 −10 AU from the binary. As expected, the rings orbit slightly closer into the binary than as reported by Maravelias et al (2018) due to the lower masses of the binary components reported in Porter et al (2021a). These correspond to ∼ 4.7 and 45 semi-major axes of the binary, respectively.…”

Section: Radii Of the Circumbinary Ringssupporting

confidence: 72%

“…Marchiano et al (2012) finds that the dust envelope begins at ∼ 230 𝑅 pr . Using 𝑅 pr = 27 +9 −7 𝑅 from Porter et al (2021a), this corresponds to the dust envelope radius of 29 +10 −7 AU. This places the outer O I ring in a similar region to the inner edge of the system's dust envelope.…”

Section: Radii Of the Circumbinary Ringsmentioning

confidence: 99%

“…Gaia Data Release 2 distance, 𝑑, and stellar parameters of the primary in GG Car, where 𝑀 pr is the mass of the primary, 𝑀 sec is the mass of the secondary, 𝑇 eff is the effective temperature of the primary, 𝐿 pr is the luminosity of the primary, 𝑅 pr is the radius of the primary, 𝑎 bin is the binary semi-major axis, 𝑒 bin the binary orbital eccentricity, and 𝜔 bin is the binary's argument of periastron. All values taken from Porter et al (2021a) except 𝑇 eff , which is taken from Marchiano et al (2012).…”

Section: Introductionmentioning

confidence: 99%

“…Its well known ∼31-day orbital period has long been observed photometrically and spectroscopically (Kruytbosch 1930;Greenstein 1938;Hernandez et al 1981;Gosset et al 1984Gosset et al , 1985van Leeuwen et al 1998;Marchiano et al 2012). Porter et al (2021a) used the spectroscopic variation of the emission lines from the wind to determine an accurate orbital solution of the binary and constrain the mass of the secondary, which is of unknown class. Table 1 lists the known stellar parameters of GG Car and the binary separation and eccentricity.…”

Section: Introductionmentioning

confidence: 99%

“…In the present study, we analyse GG Car's circumbinary atomic emission lines in high resolution FEROS spectra in the context of the updated orbital parameters and stellar masses reported in Porter et al (2021a). Section 2 describes the FEROS observations; Section 3 presents the detected circumbinary atomic emission lines; Section 4 describes the thin-ring model that is used to fit the circumbinary emission lines; Section 5 presents the results of the fitting; Section 6 discusses these results in the context of the new orbital solution of Porter et al (2021a) and presents the results of smoothed-particle hydrodynamic simulations which can recreate the observed variability of the emission lines; and Section 7 presents our conclusions.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Radii Of the Circumbinary Ringssupporting

confidence: 72%

Section: Radii Of the Circumbinary Ringsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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Science with a Small Two-Band UV-Photometry Mission II: Observations of Stars and Stellar Systems

Krtička,

Benáček,

Budaj

et al. 2024

Space Sci Rev

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We outline the impact of a small two-band UV-photometry satellite mission on the field of stellar physics, magnetospheres of stars, binaries, stellar clusters, interstellar matter, and exoplanets. On specific examples of different types of stars and stellar systems, we discuss particular requirements for such a satellite mission in terms of specific mission parameters such as bandpass, precision, cadence, and mission duration. We show that such a mission may provide crucial data not only for hot stars that emit most of their light in UV, but also for cool stars, where UV traces their activity. This is important, for instance, for exoplanetary studies, because the level of stellar activity influences habitability. While the main asset of the two-band UV mission rests in time-domain astronomy, an example of open clusters proves that such a mission would be important also for the study of stellar populations. Properties of the interstellar dust are best explored when combining optical and IR information with observations in UV.It is well known that dust absorbs UV radiation efficiently. Consequently, we outline how such a UV mission can be used to detect eclipses of sufficiently hot stars by various dusty objects and study disks, rings, clouds, disintegrating exoplanets or exoasteroids. Furthermore, UV radiation can be used to study the cooling of neutron stars providing information about the extreme states of matter in the interiors of neutron stars and used for mapping heated spots on their surfaces.

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Probabilistic orbits and dynamical masses of emission-line binaries

Grant

Blundell

2021

Monthly Notices of the Royal Astronomical Society

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The observed orbits of emission-line stars may be affected by systematics owing to their broad emission lines being formed in complex and extended environments. This is problematic when orbital parameter probability distributions are estimated assuming radial-velocity data are solely comprised of Keplerian motion plus Gaussian white noise, leading to overconfident and inaccurate orbital solutions, with implications for the inferred dynamical masses and hence evolutionary models. We present a framework in which these systems can be meaningfully analysed. We synthesise benchmark datasets, each with a different and challenging noise formulation, for testing the performance of different algorithms. We make these datasets freely available with the aim of making model validation an easy and standardised practice in this field. Next, we develop an application of Gaussian processes to model the radial-velocity systematics of emission-line binaries, named marginalised $\mathcal {GP}$. We benchmark this algorithm, along with current standardised algorithms, on the synthetic datasets and find our marginalised $\mathcal {GP}$ algorithm performs significantly better than the standard algorithms for data contaminated by systematics. Finally, we apply the marginalised $\mathcal {GP}$ algorithm to four prototypical emission-line binaries: Eta Carinae, GG Carinae, WR 140, and WR 133. We find systematics to be present in several of these case studies; and consequently, the predicted orbital parameter distributions, and dynamical masses, are modified from those previously determined.

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GG Carinae: orbital parameters and accretion indicators from phase-resolved spectroscopy and photometry

Cited by 9 publications

References 86 publications

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

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

Science with a Small Two-Band UV-Photometry Mission II: Observations of Stars and Stellar Systems

Probabilistic orbits and dynamical masses of emission-line binaries

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