NOEMA maps the CO J = 2 − 1 environment of the red supergiant $\mu$ Cep★

Montargès, M.; Homan, W.; Keller, Daniel M.; Clementel, Nicola; Shetye, S.; Decin, L.; Harper, G. M.; Royer, P.; Winters, J. M.; Bertre, T. Le; Richards, A. M. S.

doi:10.1093/mnras/stz397

Cited by 34 publications

(27 citation statements)

References 53 publications

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“…The emission of different species traced by ALMA, especially emission of SO (Fig. 3), reveals excitation variations or chemical inhomogeneities within the wind, not unlike those known from genuine red supergiants Adande et al 2013;Montargès et al 2019). As the stellar remnant is expected to be highly magnetic (Soker & Tylenda 2007;Schneider et al 2020), perhaps some of these asymmetries can be linked to magnetism.…”

Section: Molecular Gas In the Remnant Of V838 Monmentioning

confidence: 95%

V838 Monocerotis as seen by ALMA: A remnant of a binary merger in a triple system

Kamiński

Tylenda

Kiljan

et al. 2021

A&A

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Context. V838 Mon erupted in 2002, quickly becoming the prototype of a new type of stellar eruption known today as the (luminous) red nova. Red nova outbursts are thought to be caused by stellar mergers. The merger in V838 Mon took place in a triple or higher system involving two B-type stars. Aims. We wish to characterize the merger remnant ~17 yr after the eruption to learn more about the remaining system, the progenitor, and the merger physics. Methods. We mapped the merger site with ALMA at a resolution of ~25 mas, or 148 au for a distance of 5.9 kpc, in continuum dust emission and in rotational lines of simple molecules, including CO, SiO, SO, SO2, AlOH, and H2S. We use radiative transfer calculations to reproduce the architecture of the remnant at the epoch of the ALMA observations. We also make use of optical spectroscopy data obtained mainly with VLT/X-shooter and SALT/HRS. Results. For the first time, we identify the position of the B-type companion relative to the outbursting component of V838 Mon. The stellar remnant is surrounded by a clumpy wind with characteristics similar to those of the winds of red supergiants. The merger product is also associated with an elongated structure of 17.6 × 7.6 mas (104 × 45 au) seen in continuum emission, and which we interpret as a disk seen at a moderate inclination. Maps of continuum and molecular emission also show a complex region of interaction between the B-type star (its gravity, radiation, and wind) and the flow of matter ejected in 2002. The remnant’s molecular mass is about 0.1 M⊙ and the dust mass is 8.3 × 10−3 M⊙. The mass of the atomic component remains unconstrained. Conclusions. The most interesting region for understanding the merger of V838 Mon lies in its direct vicinity and appears elongated, but details of its substructure remain unknown. To study it further and in more detail will require even higher angular resolutions. ALMA maps show us an extreme form of interaction between the merger ejecta and the distant (~250 au) companion. This interaction is similar to that known from the Anteres AB system but at a much higher mass loss rate. The B-type star not only deflects the merger ejecta but also changes its molecular composition with an involvement of circumstellar shocks. The ALMA view of V838 Mon offers the best images of a merger site so far.

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Section: Molecular Gas In the Remnant Of V838 Monmentioning

confidence: 95%

V838 Monocerotis as seen by ALMA: A remnant of a binary merger in a triple system

Kamiński

Tylenda

Kiljan

et al. 2021

A&A

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“…de Wit et al (2008) derived the mass-loss rate of µ Cep from the presence of an extended circumstellar shell at 25 µm and they conclude that it is on the order of a few 10 −7 M yr −1 . More recently, De Beck et al (2010), Mauron & Josselin (2011), Shenoy et al (2016), andMontargès et al (2019) derived massloss rates of a few 10 −6 M yr −1 for µ Cep. This value is much smaller than that of other RSGs, where the mass-loss rate may be orders of magnitude larger (Schuster et al 2006).…”

Section: The Red Supergiant Star µ Cepmentioning

confidence: 97%

Tomography of cool giant and supergiant star atmospheres

Kravchenko

Chiavassa

Eck

et al. 2019

A&A

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Context. Red supergiants are cool massive stars and are the largest and the most luminous stars in the Universe. They are characterized by irregular or semi-regular photometric variations, the physics of which is not clearly understood. Aims. The paper aims to derive the velocity field in the red supergiant star μ Cep and to relate it to the photometric variability with the help of the tomographic method. Methods. The tomographic method allows one to recover the line-of-sight velocity distribution over the stellar disk and within different optical-depth slices. This method was applied to a series of high-resolution spectra of μ Cep, and these results are compared to those obtained from 3D radiative-hydrodynamics CO5BOLD simulations of red supergiants. Fluctuations in the velocity field are compared with photometric and spectroscopic variations, the latter were derived from the TiO band strength and serve, at least partly, as a proxy of the variations in effective temperature. Results. The tomographic method reveals a phase shift between the velocity and spectroscopic and photometric variations. This phase shift results in a hysteresis loop in the temperature – velocity plane with a timescale of a few hundred days, which is similar to the photometric one. The similarity between the hysteresis loop timescale measured in μ Cep and the timescale of acoustic waves disturbing the convective pattern suggests that such waves play an important role in triggering the hysteresis loops.

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“…VY CMa may be the best known source to display such episodic mass loss but other Galactic red supergiants have highly structured outflows too (e.g. Mauron 1997; Montargès et al 2019). There may be also extragalactic analogs -clumpy structures in winds of red supergiants that are immediate progenitors of core-collapse supernovae (SNe) give rise to particular observational characteristics of the explosions, including radio and X-ray emission.…”

Section: Introductionmentioning

confidence: 99%

Massive dust clumps in the envelope of the red supergiant VY Canis Majoris

Kamiński

2019

A&A

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The envelope of the red supergiant VY CMa has long been considered an extreme example of episodic mass loss that is possibly taking place in other cool and massive evolved stars. Recent (sub-)millimeter observations of the envelope revealed the presence of massive dusty clumps within 800 mas from the star which reinforce the picture of drastic mass-loss phenomena in VY CMa. We present new ALMA observations at an angular resolution of 0.1 and at an unprecedented sensitivity that reveal further details about the dusty clumps. We resolve more discrete features and identify a submillimeter counterpart of a more distant Clump SW known from visual observations. The brightest clump, named C, is marginally resolved in the observations. Gas seen against the resolved continuum emission of clump C produces a molecular spectrum in absorption, in lines of mainly sulfur-bearing species. Except for SW Clump, no molecular emission is found to be associated with the dusty clumps and we propose that the dusty structures have an atypically low gas content. We attempt to reproduce the properties of the dusty clumps through three-dimensional radiative-transfer modeling. Although a clump configuration explaining the observations is found, it is not unique. A very high optical depth of all clumps to the stellar radiation make the modeling very challenging and requires unrealistically high dust masses for one of them. It is suggested that the dusty features have substructures, e.g. porosity, that allows deeper penetration of stellar photons within the clumps than in a homogeneous configuration. A comparison of the estimated clumps ages to variations in the stellar visual flux for over a century suggests that the mechanism responsible for their formation is not uniquely manifested by enhanced or strongly diminished visual light. The study demonstrates that the dusty mass-loss episodes of VY CMa are indeed unparalleled among all known non-explosive stars. The origin of these episodes remains an unsolved problem.

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NOEMA maps the CO J = 2 − 1 environment of the red supergiant $\mu$ Cep★

Cited by 34 publications

References 53 publications

V838 Monocerotis as seen by ALMA: A remnant of a binary merger in a triple system

V838 Monocerotis as seen by ALMA: A remnant of a binary merger in a triple system

Tomography of cool giant and supergiant star atmospheres

Massive dust clumps in the envelope of the red supergiant VY Canis Majoris

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