Wide system containing a B type star.Wide system containing a B type star.

Explosion of the hot companion up Explosion of the hot companion up to Mto MV V == – –1010mm..

Cool K0 – M giant in outburst.Cool K0 – M giant in outburst.

Mass equal to a few solar masses Mass equal to a few solar masses erupted into space.erupted into space.

Very cool oxygen-rich stellar Very cool oxygen-rich stellar remnant, supergiant of L – M type.remnant, supergiant of L – M type.

Not a classical nova, a sample of a Not a classical nova, a sample of a new class of astrophysical objects. new class of astrophysical objects.

What is a red nova?What is a red nova?

Tycho Brage observes a sudden appearance of a nova star in 1572 (Flammarion Tycho Brage observes a sudden appearance of a nova star in 1572 (Flammarion textbook, 1902). In the Flammarion’s textbook all the novae were explained as a textbook, 1902). In the Flammarion’s textbook all the novae were explained as a result of stellar collisions. result of stellar collisions.

A term of nova means only a new A term of nova means only a new star unseen earlier.star unseen earlier.

GCVS editors did not believe that the star might GCVS editors did not believe that the star might be both a nova and a red supergiant as written in be both a nova and a red supergiant as written in different papers and gave It two namesdifferent papers and gave It two names

The photometric history of V838 Mon. The photometric history of V838 Mon. I. The 2002 outburstI. The 2002 outburst

Dust Dust formationformation

L type spectrum out of the V bandL type spectrum out of the V band

Spectrum ofSpectrum of V838 Mon in the outburstV838 Mon in the outburst ( (SAO RAS SAO RAS 1-1-mm Zeiss telescopeZeiss telescope))Resembles K0I type star, but the absorption lines are 3-4 times strongerResembles K0I type star, but the absorption lines are 3-4 times stronger

Spectra of V838 Mon in the different phases of the outburstSpectra of V838 Mon in the different phases of the outburst

Pre-maximumPre-maximum

Shock wave in Shock wave in the peak of the peak of outburstoutburst

After the After the peak of peak of outburstoutburst

Line profiles of high-resolution spectra V838 Mon in the Line profiles of high-resolution spectra V838 Mon in the peak of outburst.peak of outburst.BTA/NES spectra (resolution ~1 km/s) first analysed by BTA/NES spectra (resolution ~1 km/s) first analysed by Kipper et al. (2004)Kipper et al. (2004)

Classical P Cyg profiles:Classical P Cyg profiles:

Smooth profiles, ~radially Smooth profiles, ~radially symmetric outflowsymmetric outflow

The photometric history of V838 Mon. II. Pre- and The photometric history of V838 Mon. II. Pre- and post - explosion evolutionpost - explosion evolution

Digital reduction of Sonneberg (Germany) and Sternberg Institute (Moscow, Russia) Digital reduction of Sonneberg (Germany) and Sternberg Institute (Moscow, Russia) photographic plates.photographic plates.

V838 Mon progenitor. Photography taken on V838 Mon progenitor. Photography taken on 1943 February 28 with the 40-cm astrograph 1943 February 28 with the 40-cm astrograph of Sonneberg Observatory (Germany).of Sonneberg Observatory (Germany).

Fragment of HST imageFragment of HST image

Single B3V starSingle B3V star

V838 Mon, binary of B3V V838 Mon, binary of B3V starsstars

The photometric The photometric post-outburst post-outburst history of history of V838 Mon . V838 Mon . Different filters.Different filters.

Capture and engulf Capture and engulf of its B3V of its B3V companion.companion.

Julian Date Julian Date

B3V star B3V star inside the red inside the red supergiant!supergiant!

Radius of Radius of the red the red supergiant it supergiant it equal to equal to 30000 Rsun30000 Rsun

Spectral energy distributionSpectral energy distribution V838 Mon before the outburst V838 Mon before the outburst (progenitor) and after outburst (progenitor) and after outburst (L type supergiant in (L type supergiant in 2002). Corrected for reddening of E(B-V)=0.77.2002). Corrected for reddening of E(B-V)=0.77.

Unreddened spectral energy distributions of V838 Mon Unreddened spectral energy distributions of V838 Mon components. components.

If we know correct energy distributions of progenitor binary and a surviving If we know correct energy distributions of progenitor binary and a surviving B3V companion, we can calculate the energy distribution of exploded star. It B3V companion, we can calculate the energy distribution of exploded star. It was a B3V star, too.was a B3V star, too.

Cluster of B type stars around V838 Mon. Cluster of B type stars around V838 Mon. Color-Magnitude diagramColor-Magnitude diagram

The location of V838 Mon components on the Afsar & Bond’s CM The location of V838 Mon components on the Afsar & Bond’s CM diagram of the cluster. Both components have the reddening equal to diagram of the cluster. Both components have the reddening equal to the cluster’s one but are low-luminosity stars.the cluster’s one but are low-luminosity stars.

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Wavelength, AngstremWavelength, Angstrem

Post-outburst Post-outburst spectral spectral evolution of evolution of V838 MonV838 Mon

Approach & Approach & engulfengulf

Photometric history of V4332 Sgr. I.Photometric history of V4332 Sgr. I.

POSS-1 1950POSS-1 1950

The light curve in the R filter. Brightening The light curve in the R filter. Brightening before outburst is seenbefore outburst is seen

Photometric history of V4332 Sgr. II. Photometric history of V4332 Sgr. II. V band light curveV band light curve

SAI, 1986SAI, 1986

Spectral Spectral energy energy distributions of distributions of V4332 Sgr V4332 Sgr before and before and after 1994 after 1994 outburstoutburst

Reddening of E(B-V)=0.32 is Reddening of E(B-V)=0.32 is taken into account.taken into account.

V4332 Sgr spectrum 11 years after outburstV4332 Sgr spectrum 11 years after outburst

Resonance lines of Al I,Resonance lines of Al I, Ca I, Sr I; triplets of Mn I, Cr I; intercombination line ofCa I, Sr I; triplets of Mn I, Cr I; intercombination line of Mg I Mg I 45714571ÅÅ; faint emissions of Rb I; faint emissions of Rb I; ; molecular emissions ofmolecular emissions of AlOAlO, , TiOTiO, , large number of Cr I large number of Cr I lines and widelines and wide TiO bands ofTiO bands of M7M7 type star with the temperature of type star with the temperature of 2700К. 2700К.

Emission line spectrum belongs to cool gas nebulaEmission line spectrum belongs to cool gas nebula.. T=1100K. T=1100K.

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WavelengthWavelength

SlitSlit

Comparison of two red novae spectra, V4332 Sgr Comparison of two red novae spectra, V4332 Sgr and V838 Mon in 2007 and V838 Mon in 2007

V838 Mon surroundings and V838 Mon surroundings and Light echo Light echo

Light echo ofLight echo of V838 MonV838 MonCompared with X-ray light echo ofCompared with X-ray light echo ofGRB 031203GRB 031203

Our images taken Our images taken with 1-m Zeiss with 1-m Zeiss telescopetelescope

First HST image of V838 Mon light echo taken on 2002 April 30 in B First HST image of V838 Mon light echo taken on 2002 April 30 in B band. Arcs and the central gap are seenband. Arcs and the central gap are seen

Model of light echoModel of light echo

ObserverObserver

Boundary Boundary of the dense interstellar of the dense interstellar mediummedium

Light yearsLight years

Echo expansion Echo expansion in four in four directionsdirections

Superluminal partSuperluminal part

Computer Computer modeling of modeling of surrounding surrounding dust nebuladust nebula

Distance = 6 kpc generally acceptedDistance = 6 kpc generally accepted

Different structures of nebulosity Different structures of nebulosity being cut by narrow ellipsoid give being cut by narrow ellipsoid give the arcs the arcs

Distance = 6 kpcDistance = 6 kpc

Bad approximation of Bad approximation of superluminal partsuperluminal part

Computer modeling of light echo. II. Computer modeling of light echo. II. Distance = 4 kpc.Distance = 4 kpc.

We assume that V838 Mon components both are young pre main We assume that V838 Mon components both are young pre main sequence stars in the stage of gravitational contraction, and the sequence stars in the stage of gravitational contraction, and the ignition of hydrogen in the center of one of them gave a powerful ignition of hydrogen in the center of one of them gave a powerful push to star expansion. push to star expansion.

Later, when the radiation of the internal burning and shock waves Later, when the radiation of the internal burning and shock waves reached the surface, its area became so large that could not be reached the surface, its area became so large that could not be heated up to high temperature. heated up to high temperature.

This may be the case why red novae look like cool supergiants. This may be the case why red novae look like cool supergiants.

CONCLUSIONCONCLUSION

Not a Thorne – Zitkow like event. No place for a neutron star Not a Thorne – Zitkow like event. No place for a neutron star in the young binary system. Exploding star had zero age in the young binary system. Exploding star had zero age main sequence composition (Kipper et al., 2006).main sequence composition (Kipper et al., 2006).

Thank youThank you