Shock Breakout in Dense Circumstellar Material with Application to PS1-13arp

Stars in the earliest phases of their formation, i.e., those accreting the main component of their final mass, are deeply embedded within dense cores of dust and molecular material. Because of the high line-of-sight extinction and the large amount of circumstellar material, stellar emission is reprocessed by dust into long wavelength radiation, typically in the far-infrared and sub-millimeter bands. Consequently, the youngest sources are strong submillimeter continuum sources, and often undetectable as point sources in the near-infrared and optical. The most deeply embedded of these sources have been labelled “Class 0” sources by André, Ward-Thompson, & Barsony (1994), in an extension of the spectral energy distribution classification scheme first proposed by Adams, Lada, & Shu (1987).

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Revealing the Mass Loss Structures of Four Key Massive Binaries Using Optical Spectropolarimetry

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314007042 ◽

2014 ◽

Vol 9 (S307) ◽

pp. 336-341

Author(s):

Jamie R. Lomax

Keyword(s):

Mass Loss ◽

Binary Systems ◽

Hot Spot ◽

Polarized Light ◽

Opening Angle ◽

Geometric Information ◽

Intrinsic Polarization ◽

Polarization Component ◽

Circumstellar Material ◽

Large Opening

AbstractThe majority of massive stars are members of binary systems. However, in order to understand their evolutionary pathways, mass and angular momentum loss from these systems needs to be well characterized. Self-consistent explanations for their behavior across many wavelength regimes need to be valid in order to illuminate key evolutionary phases. I present the results of linear spectropolarimetric studies of three key binaries (β Lyrae, V356 Sgr, V444 Cyg, and WR 140) which reveal important geometric information about their circumstellar material. β Lyrae exhibits a repeatable discrepancy between secondary eclipse in the total and polarized light curves that indicates an accretion hot spot has formed on the edge of the disk in the system. The existence of this hot spot and its relationship to bipolar outflows within the system is important in the understanding of mass transfer dynamics in Roche-lobe overflow binaries. Preliminary work on V356 Sgr suggests the system maybe surrounded by a common envelope. V444 Cyg shows evidence that its shock creates a cone with a large opening angle of missing material around the WN star. This suggests the effects of radiative inhibition or braking, can be significant contributors to the location and shape of the shock within colliding wind binaries. The intrinsic polarization component of WR 140 is likely due to the formation of dust within the system near periastron passages. Continued work on these and additional objects will provide new and important constraints on the mass loss structures within binary systems.

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Unidentified emission features in the R Coronae Borealis star V854 Centauri

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731549 ◽

2018 ◽

Vol 610 ◽

pp. L6 ◽

Cited By ~ 2

Author(s):

L. C. Oostrum ◽

B. B. Ochsendorf ◽

L. Kaper ◽

A. G. G. M. Tielens

Keyword(s):

Near Infrared ◽

Physical Nature ◽

The Other ◽

Large Telescope ◽

Circumstellar Material ◽

Spatially Resolved ◽

Broad Emission ◽

Very Large Telescope ◽

New Feature ◽

Molecular Nature

During its 2012 decline, the R Coronae Borealis star (RCB) V854 Cen was spectroscopically monitored with X-shooter on the ESO Very Large Telescope. The obscured optical and near-infrared spectrum exhibits many narrow and several broad emission features, as previously observed. The envelope is spatially resolved along the slit and allows for a detailed study of the circumstellar material. In this Letter, we report on the properties of a number of unidentified visual emission features (UFs), including the detection of a new feature at 8692 Å. These UFs have been observed in the Red Rectangle (RR), but their chemical and physical nature is still a mystery. The previously known UFs behave similarly in the RR and in V854 Cen, but are not detected in six other observed RCBs. Some hydrogen might be required for the formation of their carrier(s). The λ8692 UF is present in all RCBs. Its carrier is likely of a carbonaceous molecular nature, presumably different from that of the other UFs.

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A search for circumstellar material around B-type stars in the Galactic halo

Monthly Notices of the Royal Astronomical Society ◽

10.1046/j.1365-8711.2002.05856.x ◽

2002 ◽

Vol 336 (4) ◽

pp. 1147-1154 ◽

Cited By ~ 1

Author(s):

H. R. M. Magee ◽

W. R. J. Rolleston ◽

P. L. Dufton ◽

F. P. Keenan ◽

C. J. Mooney

Keyword(s):

Galactic Halo ◽

Circumstellar Material

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A Reader Friendly Formalism for the Circumstellar Material-supernova Ejecta Interaction Model

Research Notes of the AAS ◽

10.3847/2515-5172/abba7b ◽

2020 ◽

Vol 4 (9) ◽

pp. 162

Author(s):

Liang-Duan Liu ◽

Ling-Jun Wang ◽

He Gao

Keyword(s):

Interaction Model ◽

Circumstellar Material

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Interstellar Extinction in 20 Open Star Clusters

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2017.64 ◽

2017 ◽

Vol 34 ◽

Cited By ~ 1

Author(s):

Geeta Rangwal ◽

R. K. S. Yadav ◽

Alok K. Durgapal ◽

D. Bisht

Keyword(s):

Spatial Variation ◽

Star Clusters ◽

Interstellar Extinction ◽

Open Star Clusters ◽

Circumstellar Material ◽

Open Star ◽

Near Ir ◽

Spectral Class ◽

Colour Excess ◽

The Difference

AbstractThe interstellar extinction law in 20 open star clusters namely, Berkeley 7, Collinder 69, Hogg 10, NGC 2362, Czernik 43, NGC 6530, NGC 6871, Bochum 10, Haffner 18, IC 4996, NGC 2384, NGC 6193, NGC 6618, NGC 7160, Collinder 232, Haffner 19, NGC 2401, NGC 6231, NGC 6823, and NGC 7380 have been studied in the optical and near-IR wavelength ranges. The difference between maximum and minimum values of E(B − V) indicates the presence of non-uniform extinction in all the clusters except Collinder 69, NGC 2362, and NGC 2384. The colour excess ratios are consistent with a normal extinction law for the clusters NGC 6823, Haffner 18, Haffner 19, NGC 7160, NGC 6193, NGC 2401, NGC 2384, NGC 6871, NGC 7380, Berkeley 7, Collinder 69, and IC 4996. We have found that the differential colour-excess ΔE(B − V), which may be due to the occurrence of dust and gas inside the clusters, decreases with the age of the clusters. A spatial variation of colour excess is found in NGC 6193 in the sense that it decreases from east to west in the cluster region. For the clusters Berkeley 7, NGC 7380, and NGC 6871, a dependence of colour excess E(B − V) with spectral class and luminosity is observed. Eight stars in Collinder 232, four stars in NGC 6530, and one star in NGC 6231 have excess flux in near-IR. This indicates that these stars may have circumstellar material around them.

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NIKA2 observations around LBV stars Emission from stars and circumstellar material

EPJ Web of Conferences ◽

10.1051/epjconf/202022800023 ◽

2020 ◽

Vol 228 ◽

pp. 00023

Author(s):

J. Ricardo Rizzo ◽

Alessia Ritacco ◽

Cristobal Bordiu

Keyword(s):

Thermal Emission ◽

Continuum Emission ◽

Core Collapse ◽

Spectral Indices ◽

Ionized Gas ◽

Dark Cloud ◽

High Frequencies ◽

Circumstellar Material ◽

Dark Clouds ◽

Luminous Blue Variable

Luminous Blue Variable (LBV) stars are evolved massive objects, previous to core-collapse supernova. LBVs are characterized by photometric and spectroscopic variability, produced by strong and dense winds, mass-loss events and very intense UV radiation. LBVs strongly disturb their surroundings by heating and shocking, and produce important amounts of dust. The study of the circumstellar material is therefore crucial to understand how these massive stars evolve, and also to characterize their effects onto the interstellar medium. The versatility of NIKA2 is a key in providing simultaneous observations of both the stellar continuum and the extended, circumstellar contribution. The NIKA2 frequencies (150 and 260 GHz) are in the range where thermal dust and free-free emission compete, and hence NIKA2 has the capacity to provide key information about the spatial distribution of circumstellar ionized gas, warm dust and nearby dark clouds; non-thermal emission is also possible even at these high frequencies. We show the results of the first NIKA2 survey towards five LBVs. We detected emission from four stars, three of them immersed in tenuous circumstellar material. The spectral indices show a complex distribution and allowed us to separate and characterize different components. We also found nearby dark clouds, with spectral indices typical of thermal emission from dust. Spectral indices of the detected stars are negative and hard to be explained only by free-free processes. In one of the sources, G79.29+0.46, we also found a strong correlation of the 1mm and 2mm continuum emission with respect to nested molecular shells at ≈1 pc from the LBV. The spectral index in this region clearly separates four components: the LBV star, a bubble characterized by free-free emission, and a shell interacting with a nearby infrared dark cloud.

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Luminous Type II supernovae for their low expansion velocities

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1133 ◽

2020 ◽

Vol 494 (4) ◽

pp. 5882-5901 ◽

Cited By ~ 3

Author(s):

Ó Rodríguez ◽

G Pignata ◽

J P Anderson ◽

T J Moriya ◽

A Clocchiatti ◽

...

Keyword(s):

Near Infrared ◽

Current Data ◽

Type Ii ◽

Data Set ◽

Circumstellar Material ◽

V Band ◽

Dominant Component ◽

Absolute Magnitudes ◽

Using Data ◽

Early Interaction

ABSTRACT We present optical and near-infrared data of three Type II supernovae (SNe II), SN 2008bm, SN 2009aj, and SN 2009au. These SNe display the following common characteristics: signs of early interaction of the ejecta with circumstellar material (CSM), blue B − V colours, weakness of metal lines, low expansion velocities, and V-band absolute magnitudes 2–3 mag brighter than those expected for normal SNe II based on their expansion velocities. Two more SNe reported in the literature (SN 1983K and LSQ13fn) share properties similar to our sample. Analysing this set of five SNe II, which are luminous for their low expansion velocities (LLEV), we find that their properties can be reproduced assuming ejecta–CSM interaction that lasts between 4 and 11 weeks post-explosion. The contribution of this interaction to the radiation field seems to be the dominant component determining the observed weakness of metal lines in the spectra rather than the progenitor metallicity. Based on hydrodynamic simulations, we find that the interaction of the ejecta with a CSM of ∼3.6 M⊙ can reproduce the light curves and expansion velocities of SN 2009aj. Using data collected by the Chilean Automatic Supernova Search, we estimate an upper limit for the LLEV SNe II fraction to be 2–4 per cent of all normal SNe II. With the current data set, it is not clear whether the LLEV events are a separated class of SNe II with a different progenitor system, or whether they are the extreme of a continuum mediated by CSM interaction with the rest of the normal SN II population.

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Early Blue Excess from the Type Ia Supernova 2017cbv

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318002193 ◽

2017 ◽

Vol 14 (S339) ◽

pp. 47-49

Author(s):

G. Hosseinzadeh

Keyword(s):

Light Curve ◽

Standard Type ◽

Circumstellar Material ◽

Type Ia Supernova ◽

Unusual Distribution ◽

Photometric Observations ◽

Type Ia ◽

Optical Light Curve ◽

Ia Supernovae

AbstractThis paper presented very early, high-cadence photometric observations of the nearby Type Ia SN 2017cbv. The light-curve is unique in that during the first five days of observations it has a blue bump in the U, B, and g bands which is clearly resolved by virtue of our photometric cadence of 5.7 hr during that time span. We modelled the light-curve as the combination of an early shock of the supernova ejecta against a non-degenerate companion star plus a standard Type Ia supernova component. Our best-fit model suggested the presence of a subgiant star 56 R⊙ from the exploding white dwarf, although that number is highly model-dependent. While the model matches the optical light-curve well, it over-predicts the flux expected in the ultraviolet bands. That may indicate that the shock is not a blackbody, perhaps because of line blanketing in the UV. Alternatively, it could point to another physical explanation for the optical blue bump, such as interaction with circumstellar material or an unusual distribution of the element Ni. Early optical spectra of SN 2017cbv show strong carbon absorption as far as day –13 with respect to maximum light, suggesting that the progenitor system contained a significant amount of unburnt material. These results for SN 2017cbv illustrate the power of early discovery and intense follow-up of nearby supernovæ for resolving standing questions about the progenitor systems and explosion mechanisms of Type Ia supernovæ.

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