scholarly journals The spectral energy distribution of protoplanetary discs around massive young stellar objects

2012 ◽  
Vol 428 (3) ◽  
pp. 2714-2722 ◽  
Author(s):  
Barbara Ercolano ◽  
Antonia Bevan ◽  
Thomas Robitaille
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Stellar Objects ◽  
Protoplanetary Discs

scholarly journals The evolution of the spectral energy distribution in massive young stellar objects

2008 ◽  
Vol 481 (2) ◽  
pp. 345-365 ◽  
Author(s):  
S. Molinari ◽  
S. Pezzuto ◽  
R. Cesaroni ◽  
J. Brand ◽  
F. Faustini ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Stellar Objects

scholarly journals The Real Solar Neighborhood Protostars

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Amanda L. Heiderman ◽  
Neal J. Evans
Keyword(s):  
Spatial Distribution ◽  
Spectral Energy Distribution ◽  
Solar Neighborhood ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Stellar Objects ◽  
Class System ◽  
Consistent Manner ◽  
Bona Fide

AbstractCharacterization of how dense molecular cores evolve into stars has historically been made through observational changes in their 2 to 25 μm spectral energy distribution (SED) or bolometric temperature via the Class system. Linking these observational classes to a physical protostellar phase or Stages in a consistent manner remains challenging. In order to provide a uniform indicator of whether an observationally classified embedded protostar candidate is likely to be a physical phase Stage 0 or I protostar, we performed an HCO+(J=3-2) survey of Class 0+I and Flat SED young stellar objects (YSOs) in the Spitzer nearby (D < 500 pc) Gould Belt cloud surveys. We use criteria from van Kempen et al.(2009) to classify sources as Stage 0+I or bona fide protostars and find 84% of our HCO+ detected sources meet that criteria. We recommend 0.54 Myr as an evolutionary timescale for these embedded protostars. We discuss trends in our sample with spatial distribution, molecular cloud extinction, spectral index, and bolometric temperature and luminosity.

scholarly journals The perturbed sublimation rim of the dust disk around the post-AGB binary IRAS08544-4431

2018 ◽  
Vol 616 ◽  
pp. A153 ◽  
Author(s):  
J. Kluska ◽  
M. Hillen ◽  
H. Van Winckel ◽  
R. Manick ◽  
M. Min ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Asymptotic Giant Branch ◽  
Young Stellar Objects ◽  
Radiative Transfer Model ◽  
Spectral Energy ◽  
Transfer Model ◽  
Stellar Objects ◽  
Binary Evolution

Context. Post-asymptotic giant branch (post-AGB) binaries are surrounded by stable dusty and gaseous disks similar to the ones around young stellar objects. Whereas, significant effort has been spent on modeling observations of disks around young stellar objects, the disks around post-AGB binaries have received significantly less attention, even though they pose significant constraints on theories of disk physics and binary evolution. Aims. We want to examine the structure of and phenomena at play in circumbinary disks around post-AGB stars. We continue the analysis of our near-infrared interferometric image of the inner rim of the circumbinary disk around IRAS08544-4431. We want to understand the physics governing this inner disk rim. Methods. We use a radiative transfer model of a dusty disk to reproduce simultaneously the photometry as well as the near-infrared interferometric dataset on IRAS08544-4431. The model assumes hydrostatic equilibrium and takes dust settling self-consistently into account. Results. The best-fit radiative transfer model shows excellent agreement with the spectral energy distribution up to millimeter wavelengths as well as with the PIONIER visibility data. It requires a rounded inner rim structure, starting at a radius of 8.25 au. However, the model does not fully reproduce the detected over-resolved flux nor the azimuthal flux distribution of the inner rim. While the asymmetric inner disk rim structure is likely to be the consequence of disk-binary interactions, the origin of the additional over-resolved flux remains unclear. Conclusions. As in young stellar objects, the disk inner rim of IRAS08544-4431 is ruled by dust sublimation physics. Additional observations are needed to understand the origin of the extended flux and the azimuthal perturbation at the inner rim of the disk.

scholarly journals Magnetic field dispersion in the neighbourhood of Bok Globules

2013 ◽  
Vol 9 (S302) ◽  
pp. 21-24
Author(s):  
C. V. Rodrigues ◽  
V. de S. Magalhães ◽  
J. W. Vilas-Boas ◽  
G. Racca ◽  
A. Pereyra
Keyword(s):  
Magnetic Field ◽  
Statistical Tests ◽  
Spectral Energy Distribution ◽  
Field Direction ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Magnetic Field Direction ◽  
Stellar Objects ◽  
Bok Globules ◽  
The Magnetic Field

AbstractWe performed an observational study of the relation between the interstellar magnetic field alignment and star formation in twenty (20) sky regions containing Bok Globules. The presence of young stellar objects in the globules is verified by a search of infrared sources with spectral energy distribution compatible with a pre main-sequence star. The interstellar magnetic field direction is mapped using optical polarimetry. These maps are used to estimate the dispersion of the interstellar magnetic field direction in each region from a Gaussian fit, σB. In addition to the Gaussian dispersion, we propose a new parameter, η, to measure the magnetic field alignment that does not rely on any function fitting. Statistical tests show that the dispersion of the magnetic field direction is different in star forming globules relative to quiescent globules. Specifically, the less organised magnetic fields occur in regions having young stellar objects.

scholarly journals Variability of young stellar objects in the star-forming region Pelican Nebula

2019 ◽  
Vol 627 ◽  
pp. A135 ◽  
Author(s):  
A. Bhardwaj ◽  
N. Panwar ◽  
G. J. Herczeg ◽  
W. P. Chen ◽  
H. P. Singh
Keyword(s):  
Main Sequence ◽  
T Tauri Stars ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Main Sequence Stars ◽  
Stellar Objects ◽  
Star Forming ◽  
T Tauri ◽  
Optical Wavelengths

Context. Pre-main-sequence variability characteristics can be used to probe the physical processes leading to the formation and initial evolution of both stars and planets. Aims. The photometric variability of pre-main-sequence stars is studied at optical wavelengths to explore star–disk interactions, accretion, spots, and other physical mechanisms associated with young stellar objects. Methods. We observed a field of 16′ × 16′ in the star-forming region Pelican Nebula (IC 5070) at BVRI wavelengths for 90 nights spread over one year in 2012−2013. More than 250 epochs in the VRI bands are used to identify and classify variables up to V ∼ 21 mag. Their physical association with the cluster IC 5070 is established based on the parallaxes and proper motions from the Gaia second data release (DR2). Multiwavelength photometric data are used to estimate physical parameters based on the isochrone fitting and spectral energy distributions. Results. We present a catalog of optical time-series photometry with periods, mean magnitudes, and classifications for 95 variable stars including 67 pre-main-sequence variables towards star-forming region IC 5070. The pre-main-sequence variables are further classified as candidate classical T Tauri and weak-line T Tauri stars based on their light curve variations and the locations on the color-color and color-magnitude diagrams using optical and infrared data together with Gaia DR2 astrometry. Classical T Tauri stars display variability amplitudes up to three times the maximum fluctuation in disk-free weak-line T Tauri stars, which show strong periodic variations. Short-term variability is missed in our photometry within single nights. Several classical T Tauri stars display long-lasting (≥10 days) single or multiple fading and brightening events of up to two magnitudes at optical wavelengths. The typical mass and age of the pre-main-sequence variables from the isochrone fitting and spectral energy distributions are estimated to be ≤1 M⊙ and ∼2 Myr, respectively. We do not find any correlation between the optical amplitudes or periods with the physical parameters (mass and age) of pre-main-sequence stars. Conclusions. The low-mass pre-main-sequence stars in the Pelican Nebula region display distinct variability and color trends and nearly 30% of the variables exhibit strong periodic signatures attributed to cold spot modulations. In the case of accretion bursts and extinction events, the average amplitudes are larger than one magnitude at optical wavelengths. These optical magnitude fluctuations are stable on a timescale of one year.

scholarly journals Influence of Microlensing on Spectral Anomalies of the Lensed Objects

2011 ◽  
Vol 20 (3) ◽  
Author(s):  
S. Simić ◽  
L. Č. Popović ◽  
P. Jovanović
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Angular Size ◽  
Black Body ◽  
Spectral Energy

AbstractHere we consider the influence of microlensing on the spectrum of a lensed object with the angular size 5 μas accepting that the composite emission of this object originates from three different regions arranged around its center. We assume that the lensed object has three concentric regions with a black-body emission; the temperatures of these regions are 10 000 K, 7500 K and 5000 K. We investigate how the integral spectral energy distribution (SED) of such stratified source changes due to microlensing by a group of solarmass stars. We find that the SED and flux ratios in the photometric B, V and R passbands show considerable changes during a microlens event. This indicates that the flux anomaly observed in some lensed quasars may be caused by microlensing of a stratified object.

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