Polarimetric evolution of V838 Monocerotis

Desidera, S.; Giro, E.; Munari, U.; Efimov, Yu. S.; Henden, A. A.; Benetti, S.; Tomov, T.; Bianchini, A.; Pernechele, Claudio

doi:10.1051/0004-6361:20031689

Cited by 19 publications

(25 citation statements)

References 20 publications

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“…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. Further polarisation variations were observed a few months after the outburst by Wisniewski et al (2003a), again suggesting the presence of an asymmetrical geometry of scattering material close to the star, and moreover that the distribution of this material had experience significant changes.…”

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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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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“…The enhanced flux at 18.1, 24, and 70 mm we observed in 2007 suggests that the equally strong (2007 epoch) 11.2 mm flux might not represent an additional enhancement of gas-phase molecular emission above that suggested by Lynch et al (2004) but rather represents a warm thermal dust emission component. Early postoutburst polarimetric observations (Wisniewski et al 2003a;Desidera et al 2004) indicated this ejecta was asymmetric; hence, we suggest that it is likely that dust which condenses from this ejecta will be spatially nonuniform and/or clumpy. We speculate that it is possible that one or more of these clumps eclipsed the line of sight in late 2006, producing the attenuation event reported by Bond (2006) and Munari et al (2007b).…”

Section: Bϫv Vmentioning

confidence: 80%

High Spatial Resolution Mid-IR Imaging of V838 Monocerotis: Evidence of New Circumstellar Dust Creation

Wisniewski¹,

Clampin²,

Bjorkman³

et al. 2008

ApJ

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We interpret these data as evidence that V838 Mon has experienced a new circumstellar dust creation event. We suggest that this newly created dust has condensed from the expanding ejecta produced from V838 Mon's 2002 outburst events and is most likely clumpy. We speculate that one (or more) of these clumps might have passed through the line of sight in late 2006, producing the brief multiwavelength photometric event reported by H. Bond in 2006 and U. Munari et al. in 2007b. We detect no evidence of extended emisssion above a level of ∼1 mJy at 11.2 mm and ∼7 mJy at 18.1 mm over radial distances of 1860-93,000 AU (0.3Љ-15.0Љ) from the central source. Using the simple assumption that ejecta material expands at a constant velocity of 300-500 km s Ϫ1

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“…It is also likely that the ejecta are not uniformly distributed, and hence the binary morphology preferred by the data may be "clumpiness" in the ejecta. In this context, we note that polarimetric observations during the outburst (Desidera et al 2004;Wisniewski et al 2003) indicate that the source became significantly polarized (0.7% at 5000 ). This A has been interpreted as being due to departures from spherical symmetry during the outburst.…”

Section: ϫ013 ϫ1mentioning

confidence: 83%

Interferometric Observations of V838 Monocerotis

Lane¹,

Retter²,

Thompson³

et al. 2005

ApJ

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We have used long-baseline near-IR interferometry to resolve the peculiar eruptive variable star V838 Mon and to provide the first direct measurement of its angular size. Assuming a uniform disk model for the emission, we derive an apparent angular diameter at the time of observations (2004 November-December) of 1.83 ‫ע‬ mas. For a nominal distance of kpc, this implies a linear radius of 1570 ‫ע‬ 400 R , . However, the 0.06 8 ‫ע‬ 2 data are somewhat better fitted by elliptical disk or binary component models, and we suggest that the emission may be strongly affected by ejecta from the outburst.

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Polarimetric evolution of V838 Monocerotis

Cited by 19 publications

References 20 publications

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

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

High Spatial Resolution Mid-IR Imaging of V838 Monocerotis: Evidence of New Circumstellar Dust Creation

Interferometric Observations of V838 Monocerotis

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