Absolute parameters of young stars: QZ Carinae

Walker, William S.; Blackford, Mark G.; Butland, R.; Budding, E.

doi:10.1093/mnras/stx1153

Cited by 9 publications

(9 citation statements)

References 23 publications

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“…According to our best-fit solution, the star's evolutionary stage seems to be somewhere between Siess et al (2000)'s ZAMS and early-main sequence 6 . Its age of 9.7 Myr is probably in fair agreement with QZ Car age estimates (Walker et al 2017). The best-fit ATLAS9 model is displayed in Fig.…”

Section: Spectral Modelling Of Adsupporting

confidence: 76%

Carina High-contrast Imaging Project for massive Stars (CHIPS)

Rainot

Reggiani

Sana

et al. 2020

A&A

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Context. Massive stars like company. However, low-mass companions have remained extremely difficult to detect at angular separations (ρ) smaller than 1″ (approx. 1000–3000 au, considering the typical distance to nearby massive stars) given the large brightness contrast between the companion and the central star. Constraints on the low-mass end of the companions mass-function for massive stars are needed, however, for helping, for example, to distinguish among the various scenarios that describe the formation of massive stars. Aims. With the aim of obtaining a statistically significant constraint on the presence of low-mass companions beyond the typical detection limit of current surveys (Δmag ≲ 5 at ρ ≲ 1″), we initiated a survey of O and Wolf-Rayet stars in the Carina region using the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) coronagraphic instrument on the Very Large Telescope (VLT). In this, the first paper of the series, we aim to introduce the survey, to present the methodology and to demonstrate the capability of SPHERE for massive stars using the multiple system QZ Car. Methods. We obtained VLT-SPHERE snapshot observations in the IRDIFS_EXT mode, which combines the IFS and IRDIS sub-systems and simultaneously provides us four-dimensional (4D) data cubes in two different fields-of-view: 1.73″ × 1.73″ for IFS (39 spectral channels across the YJH bands) and 12″ × 12″ for IRDIS (two spectral channels across the K band). Angular- and spectral-differential imaging techniques as well as PSF-fitting were applied to detect and measure the relative flux of the companions in each spectral channel. The latter were then flux-calibrated using theoretical SED models of the central object and compared to a grid of ATLAS9 atmosphere model and (pre-)main-sequence evolutionary tracks, providing a first estimate of the physical properties of the detected companions. Results. Detection limits of 9 mag at ρ > 200 mas for IFS, and as faint as 13 mag at ρ > 1.″8 for IRDIS (corresponding to sub-solar masses for potential companions), can be reached in snapshot observations of only a few minutes integration times, allowing us to detect 19 sources around the QZ Car system. All but two are reported here for the first time. With near-IR magnitude contrasts in the range of 4 to 7.5 mag, the three brightest sources (Ab, Ad, and E) are most likely to be physically bound. They have masses in the range of 2 to 12 M⊙ and are potentially co-eval with QZ Car central system. The remaining sources have flux contrast of 1.5 × 105 to 9.5 × 106 (ΔK ≈ 11 to 13 mag). Their presence can be explained by the local source density and they are, thus, likely to be chance alignments. If they were members of the Carina nebula, they would be sub-solar-mass pre-main sequence stars. Conclusions. Based on this proof of concept, we show that the VLT/SPHERE allows us to reach the sub-solar mass regime of the companion mass function. It paves the way for this type of observation with a large sample of massive stars to provide novel constraints on the multiplicity of massive stars in a region of the parameter space that has remained inaccessible so far.

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Section: Spectral Modelling Of Adsupporting

confidence: 76%

Carina High-contrast Imaging Project for massive Stars (CHIPS)

Rainot

Reggiani

Sana

et al. 2020

A&A

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“…We obtain the best agreement for a 2.2 M star with T eff = 9700 K, L = 25.5 L and R = 1.77 R , corresponding to a spectral type A0. According to Siess et al (2000) evolutionary tracks, its estimated age is 7.7 Myr, in fair agreement with the estimates for QZ Car (Walker et al, 2017).…”

Section: Qz Carsupporting

confidence: 73%

High-contrast imaging of massive stars: the example of QZ Car

Reggiani¹,

Rainot²,

Sana³

2020

caosp

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The formation of massive stars remains one of the most intriguing questions in astrophysics today. Several formation theories, that could potentially be tested by the multiplicity properties of their outcome, have been proposed. There are, however, observational challenges preventing us from discriminating between the different formation scenarios: massive stars are rare and found at relative large distances from us, they form on short timescales and evolve in multiple stellar systems within the gas-rich environment from which they are born. Taking advantage of the extreme-adaptive optics capabilities of VLT/SPHERE, we observed more than 70 galactic O stars, about half in the Carina nebula and another half in the galactic field or clusters and associations, aiming at characterizing their multiplicity properties. SPHERE offers unprecedented imaging contrasts which allows us to detect even the faintest companions around massive stars. Here, we illustrate its capabilities by focussing on the high-order multiple system QZ Car.

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“…References. (1)Surkova & Svechnikov (2004), (2) Budding et al (2015), (3) Budding et al (2004), (4) Hilditch et al (2007), (5) Bell et al (1987), (6) Terrell et al (2005), (7) Surina & Kang (2009), (8) Stickland et al (1998), (9) Mahy et al (2011), (10) Evans (1974), (11) Tüysüz et al (2014), (12) Ibanoglu et al (2013), (13) Martins et al (2017), (14)Bagnuolo et al (1994), (15)Lorenz et al (1994), (16)Djurašević et al (2009), (17)Walker et al (2017), (18)Çakırlı (2015), (19)Rauw et al (1999), (20)Daems & Waelkens (1997).…”

mentioning

confidence: 99%

Detailed models of interacting short-period massive binary stars

Sen

Langer

Marchant

et al. 2022

A&A

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Context. The majority of massive stars are part of binary systems. In about a quarter of these, the companions are so close that mass transfer occurs while they undergo core hydrogen burning, first on the thermal and then on the nuclear timescale. The nuclear timescale mass transfer leads to observational counterparts: the semi-detached so-called massive Algol binaries. These systems may provide urgently needed tests of the physics of mass transfer. However, comprehensive model predictions for these systems are sparse. Aims. We use a large grid of detailed evolutionary models of short-period massive binaries and follow-up population synthesis calculations to derive probability distributions of the observable properties of massive Algols and their descendants. Methods. Our results are based on ∼10 000 binary model sequences calculated with the stellar evolution code MESA, using a metallicity suitable for the Large Magellanic Cloud (LMC), covering initial donor masses between 10 M⊙ and 40 M⊙ and initial orbital periods above 1.4 d. These models include internal differential rotation and magnetic angular momentum transport, non-conservative mass and angular momentum transfer between the binary components, and time-dependent tidal coupling. Results. Our models imply ∼30, or ∼3% of the ∼1000, core hydrogen burning O-star binaries in the LMC to be currently in the semi-detached phase. Our donor models are up to 25 times more luminous than single stars of an identical mass and effective temperature, which agrees with the observed Algols. A comparison of our models with the observed orbital periods and mass ratios implies rather conservative mass transfer in some systems, while a very inefficient one in others. This is generally well reproduced by our spin-dependent mass transfer algorithm, except for the lowest considered masses. The observations reflect the slow increase of the surface nitrogen enrichment of the donors during the semi-detached phase all the way to CNO equilibrium. We also investigate the properties of our models after core hydrogen depletion of the donor star, when these models correspond to Wolf-Rayet or helium+OB star binaries. Conclusions. A dedicated spectroscopic survey of massive Algol systems may allow to derive the dependence of the efficiency of thermal timescale mass transfer on the binary parameters, as well as the efficiency of semiconvective mixing in the stellar interior. This would be a crucial step towards reliable binary models up to the formation of supernovae and compact objects.

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Absolute parameters of young stars: QZ Carinae

Cited by 9 publications

References 23 publications

Carina High-contrast Imaging Project for massive Stars (CHIPS)

Carina High-contrast Imaging Project for massive Stars (CHIPS)

High-contrast imaging of massive stars: the example of QZ Car

Detailed models of interacting short-period massive binary stars

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