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.

scholarly journals Spitzer view of Lyman break galaxies

2007 ◽  
Vol 3 (S245) ◽  
pp. 451-454
Author(s):  
Georgios E. Magdis ◽  
Dimitra Rigopoulou
Keyword(s):  
Rest Frame ◽  
Near Infrared ◽  
Optical Observations ◽  
Spectral Energy ◽  
Stellar Content ◽  
Mid Infrared ◽  
Lyman Break Galaxies ◽  
Polycyclic Aromatic ◽  
Stellar Masses ◽  
First Time

AbstractUsing a combination of deep MID-IR observations obtained by IRAC, MIPS and IRS on board Spitzer we investigate the MID-IR properties of Lyman Break Galaxies (LBGs) at z~3, establish a better understanding of their nature and attempt a complete characterisation of the population. With deep mid-infrared and optical observations of ~1000 LBGs covered by IRAC/MIPS and from the ground respectively, we extend the spectral energy distributions (SEDs) of the LBGs to mid-infrared. Spitzer data reveal for the first time that the mid-infrared properties of the population are inhomogeneous ranging from those with marginal IRAC detections to those with bright rest-frame near-infrared colors and those detected at 24μm MIPS band revealing the newly discovered population of the Infrared Luminous Lyman Break Galaxies (ILLBGs). To investigate this diversity, we examine the photometric properties of the population and we use stellar population synthesis models to probe the stellar content of these galaxies. We find that a fraction of LBGs have very red colors and large estimated stellar masses M∗>5×1010M⊙. We discuss the link between these LBGs and submm-luminous galaxies and we report the detection of rest frame 6.2 and 7.7 μm emission features arising from Polycyclic Aromatic Hydrocarbons (PAH) in the Spitzer/IRS spectrum of an infrared-luminous Lyman break galaxy at z=3.01.

scholarly journals Observational signatures of eccentric Jupiters inside gas cavities in protoplanetary discs

2021 ◽  
Author(s):  
Clément Baruteau ◽  
Gaylor Wafflard-Fernandez ◽  
Romane Le Gal ◽  
Florian Debras ◽  
Andrés Carmona ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Scattered Light ◽  
Dust Emission ◽  
Three Dimensional ◽  
Continuum Emission ◽  
Integrated Intensity ◽  
Gas Cavity ◽  
Hydrodynamical Simulations ◽  
Small Dust

Abstract Predicting how a young planet shapes the gas and dust emission of its parent disc is key to constraining the presence of unseen planets in protoplanetary disc observations. We investigate the case of a 2 Jupiter mass planet that becomes eccentric after migrating into a low-density gas cavity in its parent disc. Two-dimensional hydrodynamical simulations are performed and post-processed by three-dimensional radiative transfer calculations. In our disc model, the planet eccentricity reaches ∼0.25, which induces strong asymmetries in the gas density inside the cavity. These asymmetries are enhanced by photodissociation and form large-scale asymmetries in 12CO J=3→2 integrated intensity maps. They are shown to be detectable for an angular resolution and a noise level similar to those achieved in ALMA observations. Furthermore, the planet eccentricity renders the gas inside the cavity eccentric, which manifests as a narrowing, stretching and twisting of iso-velocity contours in velocity maps of 12CO J=3→2. The planet eccentricity does not, however, give rise to detectable signatures in 13CO and C18O J=3→2 inside the cavity because of low column densities. Outside the cavity, the gas maintains near-circular orbits, and the vertically extended optically thick CO emission displays a four-lobed pattern in integrated intensity maps for disc inclinations $\gtrsim$ 30○. The lack of large and small dust inside the cavity in our model further implies that synthetic images of the continuum emission in the sub-millimetre, and of polarized scattered light in the near-infrared, do not show significant differences when the planet is eccentric or still circular inside the cavity.

scholarly journals The circumstellar environment of EX Lupi: SPHERE and SINFONI views

2020 ◽  
Vol 641 ◽  
pp. A33
Author(s):  
E. Rigliaco ◽  
R. Gratton ◽  
Á. Kóspál ◽  
D. Mesa ◽  
V. D’Orazi ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
Scattered Light ◽  
Circumstellar Disk ◽  
T Tauri ◽  
Dual Beam ◽  
Imaging Mode ◽  
Band Spectra ◽  
First Time ◽  
Circumstellar Environment

Context. EX Lup is a well-studied T Tauri star that represents the prototype of young eruptive stars known as EXors. They are characterized by repetitive outbursts that are due to enhanced accretion from the circumstellar disk onto the star. In this paper, we analyze new adaptive optics imaging and spectroscopic observations to study EX Lup and its circumstellar environment in near-infrared in its quiescent phase. Aims. We aim to provide a comprehensive understanding of the circumstellar environment around EX Lup in quiescence, building upon the vast store of data provided by the literature. Methods. We observed EX Lup in quiescence with the high contrast imager SPHERE/IRDIS in the dual-beam polarimetric imaging mode to resolve the circumstellar environment in near-infrared scattered light. We complemented the data with earlier SINFONI spectroscopy, which was also taken in quiescence. Results. We resolve, for the first time in scattered light, a compact feature around EX Lup azimuthally extending from ~280° to ~360° and radially extending from ~0.3′′ to ~0.55′′ in the plane of the disk. We explore two different scenarios for the detected emission. The first one accounts for the emission as coming from the brightened walls of the cavity excavated by the outflow whose presence was suggested by ALMA observations in the J = 3−2 line of 12CO. The second attributes the emission to an inclined disk. In this latter case, we detect, for the first time, a more extended circumstellar disk in scattered light, which shows that a region between ~10 and ~30 au is depleted of μm-size grains. We compare the J-, H-, and K-band spectra obtained with SINFONI in quiescence with the spectra taken during the outburst, showing that all the emission lines result from the episodic accretion event. Conclusions. Based on the morphology analysis, we favor the scenario that assumes the scattered light is coming from a circumstellar disk rather than the outflow around EX Lup. We determine the origin of the observed feature as either coming from a continuous circumstellar disk with a cavity, from the illuminated wall of the outer disk, or from a shadowed disk. Moreover, we discuss the potential origins of the depleted region of μm-size grains, exploring the possibility that a sub-stellar companion may be the source of this feature.

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 Optical and near-infrared observations of the SPT2349-56 proto-cluster core at z = 4.3

2021 ◽  
Vol 502 (2) ◽  
pp. 1797-1815
Author(s):  
K M Rotermund ◽  
S C Chapman ◽  
K A Phadke ◽  
R Hill ◽  
E Pass ◽  
...  
Keyword(s):  
Near Infrared ◽  
Early Stage ◽  
Stellar Mass ◽  
Cluster Core ◽  
Cluster Galaxy ◽  
Infrared Observations ◽  
The Core ◽  
Virial Mass ◽  
Stellar Masses ◽  
Optical Surveys

ABSTRACT We present Gemini-S and Spitzer-IRAC optical-through-near-IR observations in the field of the SPT2349-56 proto-cluster at z = 4.3. We detect optical/IR counterparts for only 9 of the 14 submillimetre galaxies (SMGs) previously identified by ALMA in the core of SPT2349-56. In addition, we detect four z ∼ 4 Lyman-break galaxies (LBGs) in the 30 arcsec-diameter region surrounding this proto-cluster core. Three of the four LBGs are new systems, while one appears to be a counterpart of one of the nine observed SMGs. We identify a candidate brightest cluster galaxy (BCG) with a stellar mass of $(3.2^{+2.3}_{-1.4})\times 10^{11}$ M⊙. The stellar masses of the eight other SMGs place them on, above, and below the main sequence of star formation at z ≈ 4.5. The cumulative stellar mass for the SPT2349-56 core is at least (12.2 ± 2.8) × 1011 M⊙, a sizeable fraction of the stellar mass in local BCGs, and close to the universal baryon fraction (0.19) relative to the virial mass of the core (1013 M⊙). As all 14 of these SMGs are destined to quickly merge, we conclude that the proto-cluster core has already developed a significant stellar mass at this early stage, comparable to z = 1 BCGs. Importantly, we also find that the SPT2349-56 core structure would be difficult to uncover in optical surveys, with none of the ALMA sources being easily identifiable or constrained through g, r, and i colour selection in deep optical surveys and only a modest overdensity of LBGs over the more extended structure. SPT2349-56 therefore represents a truly dust-obscured phase of a massive cluster core under formation.

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

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 Detection of polarized continuum emission of the Dusty S-cluster Object (DSO/G2)

2016 ◽  
Vol 11 (S322) ◽  
pp. 233-234
Author(s):  
B. Shahzamanian ◽  
M. Zajaček ◽  
M. Valencia-S. ◽  
F. Peissker ◽  
A. Eckart ◽  
...  
Keyword(s):  
Near Infrared ◽  
Galactic Center ◽  
Continuum Emission ◽  
Polarization Angle ◽  
Imaging Data ◽  
Intrinsic Geometry ◽  
Infrared Excess ◽  
Geometrical Properties ◽  
Sgr A ◽  
First Time

AbstractA peculiar source in the Galactic center known as the Dusty S-cluster Object (DSO/G2) moves on a highly eccentric orbit around the supermassive black hole with the pericenter passage in the spring of 2014. Its nature has been uncertain mainly because of the lack of any information about its intrinsic geometry. For the first time, we use near-infrared polarimetric imaging data to obtain constraints about the geometrical properties of the DSO. We find out that DSO is an intrinsically polarized source, based on the significance analysis of polarization parameters, with the degree of the polarization of ~30% and an alternating polarization angle as it approaches the position of Sgr A*. Since the DSO exhibits a near-infrared excess of Ks-L′ > 3 and remains rather compact in emission-line maps, its main characteristics may be explained with the model of a pre-main-sequence star embedded in a non-spherical dusty envelope.

scholarly journals Exocomets: A spectroscopic survey

2020 ◽  
Vol 639 ◽  
pp. A11 ◽  
Author(s):  
I. Rebollido ◽  
C. Eiroa ◽  
B. Montesinos ◽  
J. Maldonado ◽  
E. Villaver ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Excess ◽  
Small Bodies ◽  
Hot Gas ◽  
Extrasolar Systems ◽  
Circumstellar Gas ◽  
First Time ◽  
Host Stars ◽  
Weak Trend ◽  
Circumstellar Environment

Context. While exoplanets are now routinely detected, the detection of small bodies in extrasolar systems remains challenging. Since the discovery of sporadic events, which are interpreted to be exocomets (falling evaporating bodies) around β Pic in the early 1980s, only ∼20 stars have been reported to host exocomet-like events. Aims. We aim to expand the sample of known exocomet-host stars, as well as to monitor the hot-gas environment around stars with previously known exocometary activity. Methods. We have obtained high-resolution optical spectra of a heterogeneous sample of 117 main-sequence stars in the spectral type range from B8 to G8. The data were collected in 14 observing campaigns over the course of two years from both hemispheres. We analysed the Ca II K&H and Na I D lines in order to search for non-photospheric absorptions that originated in the circumstellar environment and for variable events that could be caused by the outgassing of exocomet-like bodies. Results. We detected non-photospheric absorptions towards 50% of the sample, thus attributing a circumstellar origin to half of the detections (i.e. 26% of the sample). Hot circumstellar gas was detected in the metallic lines inspected via narrow stable absorptions and/or variable blue- and red-shifted absorption events. Such variable events were found in 18 stars in the Ca II and/or Na I lines; six of them are reported in the context of this work for the first time. In some cases, the variations we report in the Ca II K line are similar to those observed in β Pic. While we do not find a significant trend in the age or location of the stars, we do find that the probability of finding CS gas in stars with larger v sin i is higher. We also find a weak trend with the presence of near-infrared excess and with anomalous (λ Boo-like) abundances, but this would require confirmation by expanding the sample.

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