V838 Monocerotis: the central star and its environment a decade after outburst

Chesneau, O.; Millour, F.; Marco, Orsola De; Bright, Stacey N.; Spang, A.; Banerjee, D. P. K.; Ashok, N. M.; Kamiński, T.; Wisniewski, John P.; Meilland, A.; Lagadec, E.

doi:10.1051/0004-6361/201424458

Cited by 34 publications

(40 citation statements)

References 36 publications

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“…3). It is also consistent with VLTI observations of the region at MIR wavelengths (Chesneau et al 2014). The dust density was assumed to increase with distance from V838 Mon as r 0.75 .…”

Section: Dustsupporting

confidence: 91%

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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“…3). It is also consistent with VLTI observations of the region at MIR wavelengths (Chesneau et al 2014). The dust density was assumed to increase with distance from V838 Mon as r 0.75 .…”

Section: Dustsupporting

confidence: 91%

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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“…In fact this is probably not really the case. As well as the finding of Chesneau et al (2014), evidence for a non-spherical morphology comes from Wisniewksi et al (2003b). They found that spectroscopic and spectropolarimetric variations took place during the outburst, this being indicative of asymmetric geometry; this result is backed up the study of Desidera et al (2004), who also found polarimetric changes during 2002.…”

Section: Point Sourcementioning

confidence: 75%

On the properties of dust and gas in the environs of V838 Monocerotis

Exter

Cox

Swinyard

et al. 2016

A&A

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Aims. We aim to probe the close and distant circumstellar environments of the stellar outburst object V838 Mon. Methods. Herschel far-infrared imaging and spectroscopy were taken at several epochs to probe the central point source and the extended environment of V838 Mon. PACS and SPIRE maps were used to obtain photometry of the dust immediately around V838 Mon, and in the surrounding infrared-bright region. These maps were fitted in 1d and 2d to measure the temperature, mass, and β of the two dust sources. PACS and SPIRE spectra were used to detect emission lines from the extended atmosphere of the star, which were then modelled to study the physical conditions in the emitting material. HIFI spectra were taken to measure the kinematics of the extended atmosphere but unfortunately yielded no detections. Results. Fitting of the far-infrared imaging of V838 Mon reveals 0.5−0.6 M of ≈19 K dust in the environs (≈2.7 pc) surrounding V838 Mon. The surface-integrated infrared flux (signifying the thermal light echo), and derived dust properties do not vary significantly between the different epochs. We measured the photometry of the point source. As the peak of the SED (Spectral Energy Distribution) lies outside the Herschel spectral range, it is only by incorporating data from other observatories and previous epochs that we can usefully fit the SED; with this we explicitly assume no evolution of the point source between the epochs. We find that warm dust with a temperature ∼300 K distributed over a radius of 150-200 AU. We fit the far-infrared lines of CO arising from the point source, from an extended environment around V838 Mon. Assuming a model of a spherical shell for this gas, we find that the CO appears to arise from two temperature zones: a cold zone (T kin ≈ 18 K) that could be associated with the ISM or possibly with a cold layer in the outermost part of the shell, and a warm (T kin ≈ 400 K) zone that is associated with the extended environment of V838 Mon within a region of radius of ≈210 AU. The SiO lines arise from a warm/hot zone. We did not fit the lines of H 2 O as they are far more dependent on the model assumed.

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“…Interferometry carried out with the Very Large Telescope Interferometer (VLTI) was the one to resolve disks around post-AGB stars (Deroo et al, 2006, Section 4.2.2), not to mention a host of disks and tori nested inside the cores of pre-planetary nebulae (PNe) (e.g., Chesneau et al, 2007) or in newly exploded stars thought to be the product of a merger (e.g., Chesneau et al, 2014, Section 7). Today, thanks to Spectro-Polarimetric High-contrast Exoplanet REsearch , SPHERE, detailed observations are being taken of AGB systems such as LB Pup where a (presumed) binary causes a bipolar outflow (Kervella et al, 2015).…”

Section: The Binary Star Toolkitmentioning

confidence: 99%

Dawes Review 6: The Impact of Companions on Stellar Evolution

Marco

Izzard

2017

Publ. Astron. Soc. Aust.

193

136

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Astrophysicists are increasingly taking into account the effects of orbiting companions on stellar evolution. New discoveries have underlined the role of binary star interactions in a range of astrophysical events, including some that were previously interpreted as being due uniquely to single stellar evolution. We review classical binary phenomena, such as type Ia supernovae, and discuss new phenomena, such as intermediate luminosity transients, gravitational wave-producing double black holes, and the interaction between stars and their planets. Finally, we reassess well-known phenomena, such as luminous blue variables, in light of interpretations that include both single and binary stars. At the same time we contextualise the new discoveries within the framework of binary stellar evolution. The last decade has seen a revival in stellar astrophysics as the complexity of stellar observations is increasingly interpreted with an interplay of single and binary scenarios. The next decade, with the advent of massive projects such as the Square Kilometre Array, the James Webb Space Telescope, and increasingly sophisticated computational methods, will see the birth of an expanded framework of stellar evolution that will have repercussions in many other areas of astrophysics such as galactic evolution and nucleosynthesis.

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V838 Monocerotis: the central star and its environment a decade after outburst

Cited by 34 publications

References 36 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

On the properties of dust and gas in the environs of V838 Monocerotis

Dawes Review 6: The Impact of Companions on Stellar Evolution

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