scholarly journals Young Stellar Objects in the Magellanic Clouds: Herschel Spectroscopy First Results

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Joana M. Oliveira ◽  
Jacco Th. van Loon ◽  
Marta Sewiło
Keyword(s):  
Gas Phase ◽  
Magellanic Clouds ◽  
Young Stellar Objects ◽  
Space Observatory ◽  
Herschel Space Observatory ◽  
Stellar Objects ◽  
Preliminary Results ◽  
Physical Conditions ◽  
First Results

AbstractWe present preliminary results from spectroscopy obtained with PACS and SPIRE onboard the Herschel Space Observatory of a sample of massive Young Stellar Objects in the Magellanic Clouds. We analyse key gas-phase cooling species (Oi], [Cii], H2O, CO, OH), in order to characterise the physical conditions in these metal-poor environments.

scholarly journals Dust Evolution in Protoplanetary Disks

1996 ◽  
Vol 150 ◽  
pp. 513-516
Author(s):  
Thomas Henning ◽  
Wolfgang Schmitt ◽  
Hubert Klahr ◽  
Rastislav Mucha
Keyword(s):  
Numerical Study ◽  
Dynamical Evolution ◽  
Dynamical Behaviour ◽  
Young Stellar Objects ◽  
Dust Particles ◽  
Circumstellar Disk ◽  
Stellar Objects ◽  
One Dimensional ◽  
First Results ◽  
Dust Evolution

AbstractThe evolution of dust particles in circumstellar disk-like structures around protostars and young stellar objects is discussed. We especially consider the coagulation of grains due to collisional aggregation and the influence of this process on the optical properties of the particles. These dust opacities are important for both the derivation of the circumstellar dust mass from submillimetre continuum observations and the dynamical behaviour of the disks.We present first results of a numerical study of the coagulation of dust grains in a turbulent protoplanetary accretion disk described by a time-dependent one-dimensional (radial) “alpha” model. The influence of grain opacity changes due to dust coagulation on the dynamical evolution of a protostellar disk is investigated. In addition, we consider the grain motion in two-dimensional disks.

scholarly journals FIR/Submm Spectroscopy with Herschel: First Results from the VNGS and H-Atlas Surveys

2011 ◽  
Vol 20 (3) ◽  
Author(s):  
Maarten Baes ◽  
Jacopo Fritz ◽  
Naseem Rangwala ◽  
Pasquale Panuzzo ◽  
Christine D. Wilson ◽  
...  
Keyword(s):  
Wavelength Range ◽  
Spectroscopic Studies ◽  
Electromagnetic Spectrum ◽  
Physical Processes ◽  
Space Observatory ◽  
Herschel Space Observatory ◽  
Distant Galaxies ◽  
First Results ◽  
Nearby Galaxies

AbstractThe FIR/submm window is one of the least-studied regions of the electromagnetic spectrum, yet this wavelength range is absolutely crucial for understanding the physical processes and properties of the ISM in galaxies. The advent of the Herschel Space Observatory has opened up the entire FIR/submm window for spectroscopic studies. We present the first FIR/submm spectroscopic results on both nearby and distant galaxies obtained in the frame of two Herschel key programs: the Very Nearby Galaxies Survey and the Herschel ATLAS.

scholarly journals Validating post-AGB candidates in the LMC and SMC using SALT spectra

2020 ◽  
Vol 641 ◽  
pp. A142
Author(s):  
R. Szczerba ◽  
M. Hajduk ◽  
Ya. V. Pavlenko ◽  
B. J. Hrivnak ◽  
B. M. Kaminsky ◽  
...  
Keyword(s):  
South African ◽  
Stellar Atmosphere ◽  
Magellanic Clouds ◽  
Emission Lines ◽  
Young Stellar Objects ◽  
Agb Stars ◽  
Large Telescope ◽  
Stellar Objects ◽  
Effective Temperatures ◽  
The Continuum

We selected a sample of post-AGB candidates in the Magellanic Clouds on the basis of their near- and mid-infrared colour characteristics. Fifteen of the most optically bright post-AGB candidates were observed with the South African Large Telescope in order to determine their stellar parameters and thus to validate or discriminate their nature as post-AGB objects in the Magellanic Clouds. The spectral types of absorption-line objects were estimated according to the MK classification, and effective temperatures were obtained by means of stellar atmosphere modelling. Emission-line objects were classified on the basis of the fluxes of the emission lines and the presence of the continuum. Out of 15 observed objects, only 4 appear to be genuine post-AGB stars (27%). In the SMC, 1 out of 4 is post-AGB, and in the LMC, 3 out 11 are post-AGB objects. Thus, we can conclude that the selected region in the colour-colour diagram, while selecting the genuine post-AGB objects, overlaps severely with other types of objects, in particular young stellar objects and planetary nebulae. Additional classification criteria are required to distinguish between post-AGB stars and other types of objects. In particular, photometry at far-IR wavelengths would greatly assist in distinguishing young stellar objects from evolved ones. On the other hand, we showed that the low-resolution optical spectra appear to be sufficient to determine whether the candidates are post-AGB objects.

scholarly journals The Extreme Outer Regions of Disk Galaxies: Star Formation and Metal Abundances

1999 ◽  
Vol 171 ◽  
pp. 196-203
Author(s):  
Annette Ferguson ◽  
Rosemary Wyse ◽  
Jay Gallagher
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
Massive Star ◽  
Spiral Galaxies ◽  
Disk Galaxies ◽  
Physical Conditions ◽  
First Results ◽  
Disk Evolution ◽  
Metal Abundances ◽  
Optical Radius

AbstractThe extreme outer regions of disk galaxies, lying at or beyond the classical optical radius defined by R25, present an opportunity to study star formation and chemical evolution under unique physical conditions, possibly reminscent of those which existed during the early stages of disk evolution. We present here some of the first results from a large study to measure star formation rates and metallicities in the extreme outer limits of a sample of nearby spiral galaxies. Despite their low gas column densities, massive star formation is often observed in these outer parts, but at an azimuthally–averaged rate much lower than that seen in the inner disk. Gas-phase O/H abundances of roughly 10% solar characterize the gas at 1.5–2 R25. The implications of our results for star formation ‘laws’ and models of disk evolution are discussed.

scholarly journals Young stellar objects close to Sgr A*

2013 ◽  
Vol 9 (S303) ◽  
pp. 144-146
Author(s):  
B. Jalali ◽  
F. I. Pelupessy ◽  
A. Eckart ◽  
S. Portegies Zwart ◽  
N. Sabha ◽  
...  
Keyword(s):  
Black Hole ◽  
Star Formation ◽  
Radius Vector ◽  
Young Stellar Objects ◽  
Infrared Excess ◽  
Stellar Objects ◽  
Physical Conditions ◽  
Strong Compression ◽  
Sgr A ◽  
Hydrodynamical Simulations

AbstractWe aim at modeling small groups of young stars such as IRS 13N, 0.1 pc away from Sgr A*, which is suggested to contain a few embedded massive young stellar objects. We perform hydrodynamical simulations to follow the evolution of molecular clumps orbiting around a 4 × 106 M⊙ black hole, to constrain the formation and the physical conditions of such groups.We find that the strong compression due to the black hole along the orbital radius vector of clumps evolving on highly eccentric orbits causes the clumps densities to increase to higher than the tidal density of Sgr A* and required for star formation. This suggests that the tidal compression from the black hole could support star formation.Additionally, we speculate that the infrared excess source G2/DSO approaching Sgr A* on a highly eccentric orbit could be associated with a dust enshrouded star that may have been formed recently through the mechanism supported by our models.

scholarly journals Studies of the Perseus Region.I.

2006 ◽  
Vol 2 (S237) ◽  
pp. 405-405
Author(s):  
Srabani Datta
Keyword(s):  
Young Stellar Objects ◽  
Stellar Objects ◽  
Star Forming ◽  
Bolometer Array ◽  
Sky Survey ◽  
Multiple Imaging ◽  
First Results ◽  
Multi Wavelength ◽  
Array Camera ◽  
Infrared Array

AbstractStudies of molecular clouds have shown that they evolve from turbulent gas and dust to form coherent, dense and connected structures. We have conducted a multi-wavelength study of one such molecular cloud, the Perseus star-forming region, which includes Barnard 1 (B1), Barnard 3(B3), Barnard 5 (B5), NGC 1333, IC 348, L1455 and L1448. The data obtained using the Infrared Array Camera (IRAC), Multiple Imaging Photometer (MIPS), the Sub-mm Common User Bolometer Array(SCUBA) and the 2 Micron All Sky Survey (2MASS)provides information about the geometric structure of the dust and gas covering large areas around young stellar objects (YSO), dust temperatures, effect of turbulence and processes of molecule formation and their relevance in the chemical and physical evolution of the cloud. This paper presents our first results.

scholarly journals Characterising the Protostellar Population of the Magellanic Clouds with VLT/SINFONI

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Jacob Ward ◽  
Joana Oliveira ◽  
Jacco van Loon ◽  
Marta Sewilo
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Emission Lines ◽  
Young Stellar Objects ◽  
Small Magellanic Cloud ◽  
Stellar Objects ◽  
Accretion Rates

AbstractAt distances of ~50 kpc and ~60 kpc for the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) respectively the Magellanic Clouds present us with a unique opportunity to study star formation in environments outside our own galaxy. Through Spitzer and Herschel photometry and spectroscopy, samples of Young Stellar Objects (YSOs) have been selected and spectroscpically confirmed in the Magellanic Clouds. Here we present some of the key results of our SINFONI K-band observations towards massive YSOs in the Magellanic Clouds. We resolve a number of Spitzer sources into multiple, previously unresolved, components and our analysis of emission lines suggest higher accretion rates and different disc properties compared with massive YSOs in the Milky Way.

scholarly journals Modeling CO, CO2and H2O Ice Abundances in the Envelopes of Young Stellar Objects in the Magellanic Clouds

2017 ◽  
Vol 13 (S332) ◽  
pp. 47-53
Author(s):  
Tyler Pauly ◽  
Robin T. Garrod
Keyword(s):  
Radiation Field ◽  
Magellanic Clouds ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Elemental Abundances ◽  
Grain Sizes ◽  
Chemical Models ◽  
Carbon Abundance ◽  
Absorption Features ◽  
Chemical Code

AbstractMassive young stellar objects (MYSOs) in the Magellanic Clouds (MCs) show infrared absorption features corresponding to significant abundances of CO, CO2and H2O ice along the line of sight, with the relative abundances of these ices varying between sources in the Magellanic Clouds and the Milky Way. We use our gas-grain chemical code MAGICKAL, with multiple grain sizes and grain temperatures, and further expand it with a treatment for increased interstellar radiation field intensity to model the elevated dust temperatures observed in the MCs. We also adjust the elemental abundances used in the chemical models, guided by observations of HII regions in these metal-poor satellite galaxies. With a grid of models, we are able to reproduce the relative ice fractions observed in MC MYSOs, indicating that metal depletion and elevated grain temperature are important drivers of the MYSO envelope ice composition. The observed shortfall in CO in the Small Magellanic Cloud can be explained by a combination of reduced carbon abundance and increased grain temperatures. The models indicate that a large variation in radiation field strength is required to match the range of observed LMC abundances.

scholarly journals First results from VLTI near-infrared interferometry on high-mass young stellar objects

2010 ◽  
Author(s):  
Stefan Kraus ◽  
Karl-Heinz Hofmann ◽  
Karl M. Menten ◽  
Dieter Schertl ◽  
Gerd Weigelt ◽  
...  
Keyword(s):  
Near Infrared ◽  
Young Stellar Objects ◽  
High Mass ◽  
Stellar Objects ◽  
First Results ◽  
Infrared Interferometry
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