scholarly journals OISTER optical and near-infrared observations of the super-Chandrasekhar supernova candidate SN 2012dn: Dust emission from the circumstellar shell

2016 ◽  
Vol 68 (5) ◽  
pp. 68 ◽  
Author(s):  
Masayuki Yamanaka ◽  
Keiichi Maeda ◽  
Masaomi Tanaka ◽  
Nozomu Tominaga ◽  
Koji S. Kawabata ◽  
...  
Keyword(s):  
Near Infrared ◽  
Dust Emission ◽  
Infrared Observations ◽  
Circumstellar Shell

Near-Infrared Photometry of Southern Galactic Wolf-Rayet Stars

1982 ◽  
Vol 99 ◽  
pp. 67-72
Author(s):  
C. Sterken ◽  
C. de Loore
Keyword(s):  
Infrared Radiation ◽  
Interstellar Dust ◽  
Near Infrared ◽  
Thermal Emission ◽  
Dust Emission ◽  
Circumstellar Dust ◽  
Infrared Photometry ◽  
Energy Distributions ◽  
Circumstellar Shell

Allen et al. (1972) observed 40 WR stars in the |1.6µ| and |2.2µ| bands, and found evidence of interstellar dust emission in the WC9 stars Ve 2–45, AS320 and HD 313643. Hackwell et al. (1974) reported 2.3 to 23 µ photometry of 19 WR stars and concluded that the excess infrared radiation from the Wolf-Rayet stars (except for the WC9 stars) could be explained by free-free emission from a hot circumstellar shell. Gehrz and Hackwell (1974) found from 2.3 to 23 µ photometry that three out of four WC stars appear to be embedded in thick circumstellar dust (graphite) shells, and concluded that WC9 stars may form a distinct Wolf-Rayet class. Cohen et al. (1975) derived energy distributions of 23 Wolf-Rayet stars from 3µ-11µ scanner spectrophotometry and infrared photometry, and concluded that WN stars show only free-free emission whereas only WC stars show dust. The excesses in WC9 stars are interpreted as thermal emission by graphite grains.

scholarly journals Multiwavelength modelling of the circumstellar environment of the massive protostar AFGL 2591 VLA 3

2020 ◽  
Vol 498 (4) ◽  
pp. 4721-4744
Author(s):  
F A Olguin ◽  
M G Hoare ◽  
K G Johnston ◽  
F Motte ◽  
H-R V Chen ◽  
...  
Keyword(s):  
Near Infrared ◽  
Dust Emission ◽  
Continuum Emission ◽  
Model Parameters ◽  
Infrared Observations ◽  
Slowing Down ◽  
Stellar Masses ◽  
First Time ◽  
Line Fitting ◽  
Circumstellar Environment

ABSTRACT We have studied the dust density, temperature, and velocity distributions of the archetypal massive young stellar object (MYSO) AFGL 2591. Given its high luminosity ($L=2\times 10^5\, \mbox{L$_{\odot}$}$) and distance (d = 3.3 kpc), AFGL 2591 has one of the highest $\sqrt{L}/d$ ratio, giving better resolved dust emission than any other MYSO. As such, this paper provides a template on how to use resolved multiwavelength data and radiative transfer to obtain a well-constrained 2D axisymmetric analytic rotating infall model. We show for the first time that the resolved dust continuum emission from Herschel 70- μm observations is extended along the outflow direction, whose origin is explained in part from warm dust in the outflow cavity walls. However, the model can only explain the kinematic features from CH3CN observations with unrealistically low stellar masses (<15 M⊙), indicating that additional physical processes may be playing a role in slowing down the envelope rotation. As part of our three-step continuum and line fitting, we have identified model parameters that can be further constrained by specific observations. High-resolution mm visibilities were fitted to obtain the disc mass (6 M⊙) and radius (2200 au). A combination of SED and near-infrared observations were used to estimate the luminosity and envelope mass together with the outflow cavity inclination and opening angles.

Near-infrared observations of dusty white dwarfs

2019 ◽  
Vol 15 (S357) ◽  
pp. 33-36
Author(s):  
Laura K. Rogers ◽  
Siyi Xu ◽  
Amy Bonsor ◽  
Simon Hodgkin ◽  
Kate Y. L. Su ◽  
...  
Keyword(s):  
Stochastic Process ◽  
White Dwarfs ◽  
Near Infrared ◽  
Dust Emission ◽  
Colour Change ◽  
Infrared Emission ◽  
Tidal Disruption ◽  
Process Variability ◽  
Infrared Observations ◽  
Excess Emission

AbstarctPlanetary material in the atmospheres of white dwarfs is thought to be scattered inwards from outer planetary systems. Dusty emission in the infrared traces the accretion. As the scattering of many small asteroids is a stochastic process, variability in the infrared emission is predicted. We report a 3 year near-infrared (J, H and K) monitoring campaign of 34 dusty, polluted white dwarfs which aims to search for dust emission variability. We find all white dwarfs have consistent near-infrared fluxes, implying the excess emission is stable. This suggests tidal disruption events which lead to large variabilities are rare and quick (<1 year) and become stable within a few years. For WD 0408–041, the system that shows both increases and decreases in dust emission over 11 years, our K band data suggest a potential colour change associated with the dust emission that needs further confirmation.

scholarly journals Physical and chemical modeling of the starless core L 1512

2020 ◽  
Vol 635 ◽  
pp. A188
Author(s):  
Sheng-Jun Lin ◽  
Laurent Pagani ◽  
Shih-Ping Lai ◽  
Charlène Lefèvre ◽  
François Lique
Keyword(s):  
Near Infrared ◽  
Dust Emission ◽  
Core Formation ◽  
Chemical Modeling ◽  
Infrared Observations ◽  
Peak Density ◽  
Star Forming ◽  
Physical Conditions ◽  
Multiple Line ◽  
Physical And Chemical

Context. The deuterium fractionation in starless cores gives us a clue to estimate their lifetime scales, thus allowing us to distinguish between dynamical theories of core formation. Cores also seem to be subject to a differential N2 and CO depletion, which was not expected from the models. Aims. We aim to create a survey of ten cores to estimate their lifetime scales and depletion profiles in detail. After describing L 183, located in Serpens, we present the second cloud of the series, L 1512, from the star-forming region Auriga. Methods. To constrain the lifetime scale, we performed chemical modeling of the deuteration profiles across L 1512 based on dust extinction measurements from near-infrared observations and nonlocal thermal equilibrium radiative transfer with multiple line observations of N2H+, N2D+, DCO+, C18O, and 13CO, plus H2D+ (110–111). Results. We find a peak density of 1.1 × 105 cm−3 and a central temperature of 7.5 ± 1 K, which are higher and lower, respectively, compared with previous dust emission studies. The depletion factors of N2H+ and N2D+ are 27−13+17 and 4−1+2 in L 1512, which are intermediate between the two other more advanced and denser starless core cases, L 183 and L 1544. These factors also indicate a similar freeze-out of N2 in L 1512, compared to the two others despite a peak density one to two orders of magnitude lower. Retrieving CO and N2 abundance profiles with the chemical model, we find that CO has a depletion factor of ~430–870 and the N2 profile is similar to that of CO unlike that toward L 183. Therefore, L 1512 has probably been living long enough so that N2 chemistry has reached steady state. Conclusions. N2H+ modeling is necessary to assess the precise physical conditions in the center of cold starless cores, rather than dust emission. L 1512 is presumably older than 1.4 Myr. Therefore, the dominating core formation mechanism should be ambipolar diffusion for this source.

scholarly journals Accretion and Outflow Activity in the Earliest Phases of Star-Formation: CO, Sub-mm Continuum, and Near-Infrared Observations

1997 ◽  
Vol 163 ◽  
pp. 725-726
Author(s):  
K.-W. Hodapp ◽  
E. F. Ladd
Keyword(s):  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Far Infrared ◽  
Point Sources ◽  
Spectral Energy ◽  
Infrared Observations ◽  
Circumstellar Material ◽  
Dense Cores ◽  
Wavelength Radiation ◽  
Main Component

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).

scholarly journals Comparison of satellite microwave backscattering (ASCAT) and visible/near-infrared reflectances (PARASOL) for the estimation of aeolian aerodynamic roughness length in arid and semi-arid regions

2012 ◽  
Vol 5 (2) ◽  
pp. 2933-2957
Author(s):  
C. Prigent ◽  
C. Jiménez ◽  
J. Catherinot
Keyword(s):  
Arid Regions ◽  
Near Infrared ◽  
Roughness Length ◽  
Aerodynamic Roughness Length ◽  
Sources Of Information ◽  
Transport Models ◽  
Dust Transport ◽  
Infrared Observations ◽  
Aerodynamic Roughness ◽  
Semi Arid

Abstract. Previous studies examined the possibility to estimate the aeolian aerodynamic roughness length from satellites, either from visible/near-infrared observations or from microwave backscattering measurements. Here we compare the potential of the two approaches and propose to merge the two sources of information to benefit from their complementary aspects, i.e. the high spatial resolution of the visible/near-infrared (PARASOL part of the A-Train) and the independence from atmospheric contamination of the active microwaves (ASCAT on board MetOp). A global map of the aeolian aerodynamic roughness length at 6 km resolution is derived, for arid and semi-arid regions. It shows very good consistency with the existing information on the properties of these surfaces. The dataset is available to the community, for use in atmospheric dust transport models.

scholarly journals Planck’s dusty GEMS

2018 ◽  
Vol 620 ◽  
pp. A60 ◽  
Author(s):  
R. Cañameras ◽  
N. P. H. Nesvadba ◽  
M. Limousin ◽  
H. Dole ◽  
R. Kneissl ◽  
...  
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Infrared Imaging ◽  
High Redshift ◽  
Dust Emission ◽  
Galaxy Cluster ◽  
Star Forming ◽  
The Galaxy ◽  
Mass Outflow ◽  
Gas Accretion

We report the discovery of a molecular wind signature from a massive intensely star-forming clump of a few 109 M⊙, in the strongly gravitationally lensed submillimeter galaxy “the Emerald” (PLCK_G165.7+49.0) at z = 2.236. The Emerald is amongst the brightest high-redshift galaxies on the submillimeter sky, and was initially discovered with the Planck satellite. The system contains two magnificient structures with projected lengths of 28.5″ and 21″ formed by multiple, near-infrared arcs, falling behind a massive galaxy cluster at z = 0.35, as well as an adjacent filament that has so far escaped discovery in other wavebands. We used HST/WFC3 and CFHT optical and near-infrared imaging together with IRAM and SMA interferometry of the CO(4–3) line and 850 μm dust emission to characterize the foreground lensing mass distribution, construct a lens model with LENSTOOL, and calculate gravitational magnification factors between 20 and 50 in most of the source. The majority of the star formation takes place within two massive star-forming clumps which are marginally gravitationally bound and embedded in a 9 × 1010 M⊙, fragmented disk with 20% gas fraction. The stellar continuum morphology is much smoother and also well resolved perpendicular to the magnification axis. One of the clumps shows a pronounced blue wing in the CO(4–3) line profile, which we interpret as a wind signature. The mass outflow rates are high enough for us to suspect that the clump might become unbound within a few tens of Myr, unless the outflowing gas can be replenished by gas accretion from the surrounding disk. The velocity offset of –200 km s−1 is above the escape velocity of the clump, but not that of the galaxy overall, suggesting that much of this material might ultimately rain back onto the galaxy and contribute to fueling subsequent star formation.

scholarly journals Near-infrared observations of the Fornax dwarf galaxy

2007 ◽  
Vol 467 (3) ◽  
pp. 1025-1036 ◽  
Author(s):  
M. Gullieuszik ◽  
E. V. Held ◽  
L. Rizzi ◽  
I. Saviane ◽  
Y. Momany ◽  
...  
Keyword(s):  
Near Infrared ◽  
Dwarf Galaxy ◽  
Infrared Observations

scholarly journals Secondary eclipses of WASP-18b – near-infrared observations with the Anglo-Australian Telescope, the Magellan Clay Telescope and the LCOGT network

2018 ◽  
Vol 483 (4) ◽  
pp. 5110-5122 ◽  
Author(s):  
L Kedziora-Chudczer ◽  
G Zhou ◽  
J Bailey ◽  
D D R Bayliss ◽  
C G Tinney ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Observations

Near-Infrared Observations of KH 15D through the 2003 February Eclipse

2004 ◽  
Vol 128 (6) ◽  
pp. 2977-2980 ◽  
Author(s):  
Roger Knacke ◽  
Sergio Fajardo-Acosta ◽  
A. T. Tokunaga
Keyword(s):  
Near Infrared ◽  
Infrared Observations
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