scholarly journals Origins of Type Ibn SNe 2006jc/2015G in interacting binaries and implications for pre-SN eruptions

2019 ◽  
Vol 491 (4) ◽  
pp. 6000-6019 ◽  
Author(s):  
Ning-Chen Sun ◽  
Jusytn R Maund ◽  
Ryosuke Hirai ◽  
Paul A Crowther ◽  
Philipp Podsiadlowski
Keyword(s):  
Main Sequence ◽  
Hubble Space Telescope ◽  
Optical Observations ◽  
Initial Mass ◽  
Binary Interaction ◽  
Lower Mass ◽  
Single Star ◽  
Circumstellar Material ◽  
Luminous Blue Variables ◽  
Star Evolution

ABSTRACT Type Ibn supernovae (SNe Ibn) are intriguing stellar explosions whose spectra exhibit narrow helium lines with little hydrogen. They trace the presence of circumstellar material (CSM) formed via pre-SN eruptions of their stripped-envelope progenitors. Early work has generally assumed that SNe Ibn come from massive Wolf–Rayet (WR) stars via single-star evolution. In this paper, we report ultraviolet (UV) and optical observations of two nearby Type Ibn SNe 2006jc and 2015G conducted with the Hubble Space Telescope (HST) at late times. A point source is detected at the position of SN 2006jc, and we confirm the conclusion of Maund et al. that it is the progenitor’s binary companion. Its position on the Hertzsprung–Russell (HR) diagram corresponds to a star that has evolved off the main sequence (MS); further analysis implies a low initial mass for the companion star (M2 ≤ 12.3$^{+2.3}_{-1.5}$ M⊙) and a secondary-to-primary initial mass ratio very close to unity (q = M2/M1 ∼ 1); the SN progenitor’s hydrogen envelope had been stripped through binary interaction. We do not detect the binary companion of SN 2015G. For both SNe, the surrounding stellar populations have relatively old ages and argue against any massive WR stars as their progenitors. These results suggest that SNe Ibn may have lower mass origins in interacting binaries. As a result, they also provide evidence that the giant eruptions commonly seen in massive luminous blue variables (LBVs) can also occur in much lower mass, stripped-envelope stars just before core collapse.

scholarly journals On the Gaia DR2 distances for Galactic luminous blue variables

2019 ◽  
Vol 488 (2) ◽  
pp. 1760-1778 ◽  
Author(s):  
Nathan Smith ◽  
Mojgan Aghakhanloo ◽  
Jeremiah W Murphy ◽  
Maria R Drout ◽  
Keivan G Stassun ◽  
...  
Keyword(s):  
Main Sequence ◽  
Mass Range ◽  
Instability Strip ◽  
Single Star ◽  
Circumstellar Material ◽  
Luminous Blue Variables ◽  
Binary Evolution ◽  
Lower Luminosity ◽  
Gaia Dr2 ◽  
Wide Swath

ABSTRACT We examine parallaxes and distances for Galactic luminous blue variables (LBVs) in the Gaia second data release (DR2). The sample includes 11 LBVs and 14 LBV candidates. For about half of the sample, DR2 distances are either similar to commonly adopted literature values, or the DR2 values have large uncertainties. For the rest, reliable DR2 distances differ significantly from values in the literature, and in most cases the Gaia DR2 distance is smaller. Two key results are that the S Doradus instability strip may not be as clearly defined as previously thought, and that there exists a population of LBVs at relatively low luminosities. LBVs seem to occupy a wide swath from the end of the main sequence at the blue edge to ∼8000 K at the red side, with a spread in luminosity reaching as low as log(L/L⊙) ≈ 4.5. The lower-luminosity group corresponds to effective single-star initial masses of 10–25 M⊙, and includes objects that have been considered as confirmed LBVs. We discuss implications for LBVs including (1) their instability and origin in binary evolution, (2) connections to some supernova (SN) impostors such as the class of SN 2008S-like objects, and (3) LBVs that may be progenitors of SNe with dense circumstellar material across a wide initial mass range. Although some of the Gaia DR2 distances for LBVs have large uncertainty, this represents the most direct and consistent set of Galactic LBV distance estimates available in the literature.

scholarly journals Revised Stellar Parameters for V471 Tau, A Post-common Envelope Binary in the Hyades

2021 ◽  
Vol 163 (1) ◽  
pp. 34
Author(s):  
Philip S. Muirhead ◽  
Jason Nordhaus ◽  
Maria R. Drout
Keyword(s):  
White Dwarf ◽  
Main Sequence ◽  
Hubble Space Telescope ◽  
Main Sequence Star ◽  
Velocity Measurements ◽  
Single Star ◽  
Orbital Parameters ◽  
Common Envelope ◽  
Star Evolution ◽  
First Time

Abstract V471 Tau is a post-common-envelope binary consisting of an eclipsing DA white dwarf and a K-type main-sequence star in the Hyades star cluster. We analyzed publicly available photometry and spectroscopy of V471 Tau to revise the stellar and orbital parameters of the system. We used archival K2 photometry, archival Hubble Space Telescope spectroscopy, and published radial-velocity measurements of the K-type star. Employing Gaussian processes to fit for rotational modulation of the system flux by the main-sequence star, we recovered the transits of the white dwarf in front of the main-sequence star for the first time. The transits are shallower than would be expected from purely geometric occultations owing to gravitational microlensing during transit, which places an additional constraint on the white-dwarf mass. Our revised mass and radius for the main-sequence star is consistent with single-star evolutionary models given the age and metallicity of the Hyades. However, as noted previously in the literature, the white dwarf is too massive and too hot to be the result of single-star evolution given the age of the Hyades, and may be the product of a merger scenario. We independently estimate the conditions of the system at the time of common envelope that would result in the measured orbital parameters today.

scholarly journals Alone but not lonely: Observational evidence that binary interaction is always required to form hot subdwarf stars

2020 ◽  
Vol 642 ◽  
pp. A180
Author(s):  
Ingrid Pelisoli ◽  
Joris Vos ◽  
Stephan Geier ◽  
Veronika Schaffenroth ◽  
Andrzej S. Baran
Keyword(s):  
Proper Motion ◽  
Binary Systems ◽  
Main Sequence ◽  
Open Clusters ◽  
Binary Interaction ◽  
Spectral Energy ◽  
Wide Binary ◽  
Single Star ◽  
Rotation Rates ◽  
Hot Subdwarfs

Context. Hot subdwarfs are core-helium burning stars that show lower masses and higher temperatures than canonical horizontal branch stars. They are believed to be formed when a red giant suffers an extreme mass-loss episode. Binary interaction is suggested to be the main formation channel, but the high fraction of apparently single hot subdwarfs (up to 30%) has prompted single star formation scenarios to be proposed. Aims. We investigate the possibility that hot subdwarfs could form without interaction by studying wide binary systems. If single formation scenarios were possible, there should be hot subdwarfs in wide binaries that have undergone no interaction. Methods. Angular momentum accretion during interaction is predicted to cause the hot subdwarf companion to spin up to the critical velocity. The effect of this should still be observable given the timescales of the hot subdwarf phase. To study the rotation rates of companions, we have analysed light curves from the Transiting Exoplanet Survey Satellite for all known hot subdwarfs showing composite spectral energy distributions indicating the presence of a main sequence wide binary companion. If formation without interaction were possible, that would also imply the existence of hot subdwarfs in very wide binaries that are not predicted to interact. To identify such systems, we have searched for common proper motion companions with projected orbital distances of up to 0.1 pc to all known spectroscopically confirmed hot subdwarfs using Gaia DR2 astrometry. Results. We find that the companions in composite hot subdwarfs show short rotation periods when compared to field main sequence stars. They display a triangular-shaped distribution with a peak around 2.5 days, similar to what is observed for young open clusters. We also report a shortage of hot subdwarfs with candidate common proper motion companions. We identify only 16 candidates after probing 2938 hot subdwarfs with good astrometry. Out of those, at least six seem to be hierarchical triple systems, in which the hot subdwarf is part of an inner binary. Conclusions. The observed distribution of rotation rates for the companions in known wide hot subdwarf binaries provides evidence of previous interaction causing spin-up. Additionally, there is a shortage of hot subdwarfs in common proper motion pairs, considering the frequency of such systems among progenitors. These results suggest that binary interaction is always required for the formation of hot subdwarfs.

scholarly journals Massive star evolution revealed in the Mass-Luminosity plane

2018 ◽  
Vol 14 (S346) ◽  
pp. 480-485
Author(s):  
Erin R. Higgins ◽  
Jorick S. Vink
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Massive Star ◽  
Main Sequence ◽  
Theoretical Models ◽  
Physical Processes ◽  
Single Star ◽  
Star Evolution ◽  
Novel Method ◽  
Massive Star Evolution

AbstractMassive star evolution is dominated by key physical processes such as mass loss, convection and rotation, yet these effects are poorly constrained, even on the main sequence. We utilise a detached, eclipsing binary HD166734 as a testbed for single star evolution to calibrate new MESA stellar evolution grids. We introduce a novel method of comparing theoretical models with observations in the ‘Mass-Luminosity Plane’, as an equivalent to the HRD (see Higgins & Vink 2018). We reproduce stellar parameters and abundances of HD166734 with enhanced overshooting (αov=0.5), mass loss and rotational mixing. When comparing the constraints of our testbed to the systematic grid of models we find that a higher value of αov=0.5 (rather than αov=0.1) results in a solution which is more likely to evolve to a neutron star than a black hole, due to a lower value of the compactness parameter.

Spectroscopy of complete populations of Wolf-Rayet binaries in the Magellanic Clouds

2018 ◽  
Vol 14 (S346) ◽  
pp. 307-315
Author(s):  
Tomer Shenar ◽  
R. Hainich ◽  
W.-R. Hamann ◽  
A. F. J. Moffat ◽  
H. Todt ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Mass Loss ◽  
Massive Stars ◽  
Large Population ◽  
Magellanic Clouds ◽  
Binary Interaction ◽  
Stellar Winds ◽  
Single Star ◽  
Mass Removal ◽  
Star Evolution

AbstractClassical Wolf-Rayet stars are evolved, hydrogen depleted massive stars that exhibit strong mass-loss. In theory, these stars can form either by intrinsic mass loss (stellar winds or eruptions), or via mass-removal in binaries. The Wolf-Rayet stars in the Magellanic Clouds are often thought to have originated through binary interaction due to the low ambient metallicity and, correspondingly, reduced wind mass-loss. We performed a complete spectral analysis of all known WR binaries of the nitrogen sequence in the Small and Large Magellanic Clouds, as well as additional orbital analyses, and constrained the evolutionary histories of these stars. We find that the bulk of Wolf-Rayet stars are luminous enough to be explained by single-star evolution. In contrast to prediction, we do not find clear evidence for a large population of low-luminosity Wolf-Rayet stars that could only form via binary interaction, suggesting a discrepancy between predictions and observations.

scholarly journals Lower Limit for NPN's Masses

1989 ◽  
Vol 131 ◽  
pp. 454-454
Author(s):  
Amos Harpaz
Keyword(s):  
Mass Loss ◽  
Lower Limit ◽  
Planetary Nebula ◽  
Mass Range ◽  
Lower Mass ◽  
Single Star ◽  
Star Evolution ◽  
Low Mass ◽  
Red Giant

The lowest mass observed for a nucleus of a planetary nebula (NPN) is about 0.55 M⊙ (Weidemann and Koester, 1983, Schonberner, 1983). Hence, Lower mass WD's should have been produced without going through the phase of a visible PN ejection. Recently, Harpaz et al. (1987), have shown that very low mass WD's (up to 0.45 M⊙) can be formed by a single star evolution from red giant branch (RGB) stars, due to mass loss along the RGB. It turns out that WD's in mass range of 0.46–0.55 M⊙ formed by a single star evolution should be formed from the AGB, without an observable PN.

scholarly journals Why binary interaction does not necessarily dominate the formation of Wolf-Rayet stars at low metallicity

2020 ◽  
Vol 634 ◽  
pp. A79 ◽  
Author(s):  
T. Shenar ◽  
A. Gilkis ◽  
J. S. Vink ◽  
H. Sana ◽  
A. A. C. Sander
Keyword(s):  
Mass Range ◽  
Magellanic Clouds ◽  
Initial Mass ◽  
Binary Interaction ◽  
Additional Contribution ◽  
Apparent Contradiction ◽  
Single Star ◽  
Binary Channel ◽  
The Galaxy ◽  
Low Metallicity

Context. Classical Wolf-Rayet (WR) stars are massive, hydrogen-depleted, post main-sequence stars that exhibit emission-line dominated spectra. For a given metallicity Z, stars exceeding a certain initial mass MsingleWR(Z) can reach the WR phase through intrinsic mass-loss or eruptions (single-star channel). In principle, stars of lower masses can reach the WR phase via stripping through binary interactions (binary channel). Because winds become weaker at low Z, it is commonly assumed that the binary channel dominates the formation of WR stars in environments with low metallicity such as the Small and Large Magellanic Clouds (SMC, LMC). However, the reported WR binary fractions of 30−40% in the SMC (Z = 0.002) and LMC (Z = 0.006) are comparable to that of the Galaxy (Z = 0.014), and no evidence for the dominance of the binary channel at low Z could be identified observationally. Here, we explain this apparent contradiction by considering the minimum initial mass MspecWR(Z) needed for the stripped product to appear as a WR star. Aims. By constraining MspecWR(Z) and MsingleWR(Z), we estimate the importance of binaries in forming WR stars as a function of Z. Methods. We calibrated MspecWR using the lowest-luminosity WR stars in the Magellanic Clouds and the Galaxy. A range of MsingleWR values were explored using various evolution codes. We estimated the additional contribution of the binary channel by considering the interval [MspecWR(Z), MsingleWR(Z)], which characterizes the initial-mass range in which the binary channel can form additional WR stars. Results. The WR-phenomenon ceases below luminosities of log L ≈ 4.9, 5.25, and 5.6 [L⊙] in the Galaxy, the LMC, and the SMC, respectively, which translates to minimum He-star masses of 7.5, 11, 17 M⊙ and minimum initial masses of MspecWR = 18, 23, 37 M⊙. Stripped stars with lower initial masses in the respective galaxies would tend not to appear as WR stars. The minimum mass necessary for self-stripping, MsingleWR(Z), is strongly model-dependent, but it lies in the range 20−30, 30−60, and ≳40 M⊙ for the Galaxy, LMC, and SMC, respectively. We find that that the additional contribution of the binary channel is a non-trivial and model-dependent function of Z that cannot be conclusively claimed to be monotonically increasing with decreasing Z. Conclusions. The WR spectral appearance arises from the presence of strong winds. Therefore, both MspecWR and MsingleWR increase with decreasing metallicity. Considering this, we show that one should not a-priori expect that binary interactions become increasingly important in forming WR stars at low Z, or that the WR binary fraction grows with decreasing Z.

scholarly journals Candidate LBV stars in galaxy NGC 7793 found via HST photometry + MUSE spectroscopy

2020 ◽  
Vol 493 (2) ◽  
pp. 2410-2428 ◽  
Author(s):  
Aida Wofford ◽  
Vanesa Ramírez ◽  
Janice C Lee ◽  
David A Thilker ◽  
Lorenza Della Bruna ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
H Ii Regions ◽  
Binary Black Holes ◽  
Luminous Blue Variables ◽  
Large Samples ◽  
Star Evolution ◽  
Large N ◽  
Binary Formation ◽  
Nearby Galaxies ◽  
Massive Star Evolution

ABSTRACT Only about 19 Galactic and 25 extragalactic bonafide luminous blue variables (LBVs) are known to date. This incomplete census prevents our understanding of this crucial phase of massive star evolution which leads to the formation of heavy binary black holes via the classical channel. With large samples of LBVs one could better determine the duration and maximum stellar luminosity which characterize this phase. We search for candidate LBVs (cLBVs) in a new galaxy, NGC 7793. For this purpose, we combine high spatial resolution images from two Hubble Space Telescope (HST) programs with optical spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE). By combining PSF-fitting photometry measured on F547M, F657N, and F814W images, with restrictions on point-like appearance (at HST resolution) and H α luminosity, we find 100 potential cLBVs, 36 of which fall in the MUSE fields. Five of the latter 36 sources are promising cLBVs which have MV ≤ −7 and a combination of: H α with a P-Cygni profile; no [O i]$\, \lambda 6300$ emission; weak or no [O iii]$\, \lambda 5007$ emission; large [N ii]/H α relative to H ii regions; and [S ii]$\, \lambda 6716$/[S ii]$\, \lambda 6731\sim 1$. It is not clear if these five cLBVs are isolated from O-type stars, which would favour the binary formation scenario of LBVs. Our study, which approximately covers one fourth of the optical disc of NGC 7793, demonstrates how by combining the above HST surveys with multi-object spectroscopy from 8-m class telescopes, one can efficiently find large samples of cLBVs in nearby galaxies.

scholarly journals The fates of massive stars: exploring uncertainties in stellar evolution with metisse

2020 ◽  
Vol 497 (4) ◽  
pp. 4549-4564
Author(s):  
Poojan Agrawal ◽  
Jarrod Hurley ◽  
Simon Stevenson ◽  
Dorottya Szécsi ◽  
Chris Flynn
Keyword(s):  
Stellar Evolution ◽  
Main Sequence ◽  
Massive Stars ◽  
Mass Range ◽  
Radial Expansion ◽  
Single Star ◽  
New Approach ◽  
Star Evolution ◽  
Order Of Magnitude ◽  
The Impact

ABSTRACT In the era of advanced electromagnetic and gravitational wave detectors, it has become increasingly important to effectively combine and study the impact of stellar evolution on binaries and dynamical systems of stars. Systematic studies dedicated to exploring uncertain parameters in stellar evolution are required to account for the recent observations of the stellar populations. We present a new approach to the commonly used single-star evolution (sse) fitting formulae, one that is more adaptable: method of interpolation for single star evolution (metisse). It makes use of interpolation between sets of pre-computed stellar tracks to approximate evolution parameters for a population of stars. We have used metisse with detailed stellar tracks computed by the modules for experiments in stellar astrophysics (mesa), the bonn evolutionary code (bec), and the Cambridge stars code. metisse better reproduces stellar tracks computed using the stars code compared to sse, and is on average three times faster. Using stellar tracks computed with mesa and bec, we apply metisse to explore the differences in the remnant masses, the maximum radial expansion, and the main-sequence lifetime of massive stars. We find that different physical ingredients used in the evolution of stars, such as the treatment of radiation-dominated envelopes, can impact their evolutionary outcome. For stars in the mass range 9–100 M⊙, the predictions of remnant masses can vary by up to 20 M⊙, while the maximum radial expansion achieved by a star can differ by an order of magnitude between different stellar models.

scholarly journals Massive star evolution in the Small Magellanic Cloud

2003 ◽  
Vol 212 ◽  
pp. 308-315 ◽  
Author(s):  
Daniel J. Lennon
Keyword(s):  
Stellar Evolution ◽  
Massive Star ◽  
Main Sequence ◽  
Single Star ◽  
Promising Alternative ◽  
Star Models ◽  
Abundance Patterns ◽  
Star Evolution ◽  
Type Giant ◽  
Massive Star Evolution

We discuss abundances for eight early B-type giant/supergiant stars in the SMC cluster NGC 330. All are nitrogen rich with an abundance approximately 1.3 dex higher than an SMC main-sequence field. Given the number of B-type stars with low rotational projected velocities in NGC 330 (all our targets have v sin i < 50 kms–1), we suggest that it is unlikely that the stars in our sample are seen almost pole-on, but rather that they are intrinsically slow rotators. Comparing these results with the predictions of stellar evolution models including the effects of rotationally induced mixing, we conclude that while the abundance patterns may indeed be reproduced, those models with initially large rotational velocities do not reproduce the observed range of effective temperatures of our sample, nor the currently observed rotational velocities. Binary models may be able to produce stars in the observed temperature range and provide a promising alternative to single star models for explaining the observations. We also discuss the clear need for stellar evolution calculations employing the correct chemical mix of carbon, nitrogen and oxygen for the SMC.

Sign in / Sign up

Export Citation Format

Share Document