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The idea that non steady accretion during the embedded phase of protostar evolution can produce the observed luminosity spread in the Herzsprung-Russell diagram (HRD) of young clusters has recently been called into question. Observations of…

Solar and Stellar Astrophysics · Physics 2015-06-05 Isabelle Baraffe , Eduard Vorobyov , Gilles Chabrier

Understanding the collapse of dense molecular cloud cores to stellar densities and the subsequent evolution of the protostar is of importance to model the feedback effects such an object has on its surrounding environment, as well as…

Solar and Stellar Astrophysics · Physics 2023-12-06 Adnan Ali Ahmad , Matthias González , Patrick Hennebelle , Benoît Commerçon

Constraining the physical and chemical evolution of molecular clouds is essential to our understanding of star formation. These investigations often necessitate knowledge of some local representative number density of the gas along the line…

Astrophysics of Galaxies · Physics 2025-04-02 Brandt A. L. Gaches , Michael Y. Grudić

We conduct numerical experiments to determine the density probability distribution function (PDF) produced in supersonic, isothermal, self-gravitating turbulence of the sort that is ubiquitous in star-forming molecular clouds. Our…

Astrophysics of Galaxies · Physics 2021-08-10 Shivan Khullar , Christoph Federrath , Mark R. Krumholz , Christopher D. Matzner

We present a study connecting the physical properties of protostellar envelopes to the morphology of the envelope-scale magnetic field. We used the ALMA polarization observations of 61 young prtostars at 0.87 mm on $\sim400-3000$ au scales…

We present the full results of our 3-year long Submillimeter Array survey of protoplanetary disks in the Orion Nebula Cluster. We imaged 23 fields at 880 microns and 2 fields at 1330 microns, covering an area of ~6.5 arcmin^2 and containing…

Solar and Stellar Astrophysics · Physics 2015-05-20 Rita K. Mann , Jonathan P. Williams

We present observational results of the thermal dust continuum emission and its linear polarization in one of the nearest massive star-forming sites Orion BN/KL in Orion Molecular Cloud-1. The observations were carried out with the…

Astrophysics of Galaxies · Physics 2015-05-19 Ya-Wen Tang , Paul T. P. Ho , Patrick M. Koch , Ramprasad Rao

We use the ellipsoidal collapse approximation to investigate the nonlinear redshift space evolution of the density field with primordial non-Gaussianity of the local f_{nl}-type. We utilize the joint distribution of eigenvalues of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Tsz Yan Lam , Vincent Desjacques , Ravi K. Sheth

Knowledge of the evolution of the low column density end of the Ly alpha forest (12.8 < log N_HI < 16.0 cm^-2) can provide substantial insight for models of structure formation and studies of the evolution of the ionizing background. Here…

Astrophysics · Physics 2007-05-23 Esther M. Hu

We present the discovery of expanding spherical shells around low to intermediate-mass young stars in the Orion A giant molecular cloud using observations of $^{12}$CO (1-0) and $^{13}$CO (1-0) from the Nobeyama Radio Observatory 45-meter…

Photoevaporating protoplanetary discs (proplyds) in the vicinity of hot massive stars, such as those found in Orion, are important objects of study for the fields of star formation, early disc evolution, planetary formation, and H II region…

Astrophysics of Galaxies · Physics 2015-06-12 Y. G. Tsamis , N. Flores-Fajardo , W. J. Henney , J. R. Walsh , A. Mesa-Delgado

We explore the evolution of the morphology density relation using the COSMOS-ACS survey and previous cluster studies. The Gini parameter measured in a Petrosian aperture is found to be an effective way of selecting early-type galaxies free…

Astrophysics · Physics 2009-11-13 P. L. Capak , R. G. Abraham , R. S. Ellis , B. Mobasher , N. Z. Scoville , K. Sheth , A. Koekemoer

We derive an analytic expression for the transitional column density value ($s_t$) between the lognormal and power-law form of the probability distribution function (PDF) in star-forming molecular clouds. Our expression for $s_t$ depends on…

Astrophysics of Galaxies · Physics 2016-12-28 Blakesley Burkhart , Kye Stalpes , David Collins

Based on the analysis of available published data and archival data along 24 sightlines (5 of which are new) we derive more accurate estimates of the column densities of OH and CH towards diffuse/translucent clouds and revisit the typically…

Astrophysics of Galaxies · Physics 2016-04-20 Bhaswati Mookerjea

Our general understanding of multiple star and planet formation is primarily based on observations of young multiple systems in low density regions like Tau-Aur and Oph. Since many, if not most, of the stars are born in clusters,…

Solar and Stellar Astrophysics · Physics 2015-06-16 S. Correia , G. Duchene , B. Reipurth , H. Zinnecker , S. Daemgen , M. G. Petr-Gotzens , R. Koehler , Th. Ratzka , C. Aspin , Q. M. Konopacky , A. M. Ghez

The early evolution of protostellar, star-forming discs, including their density structure, turbulence, magnetic dynamics, and accretion variability, remains poorly understood. We present high-resolution magnetohydrodynamic simulations,…

Solar and Stellar Astrophysics · Physics 2025-08-28 Trey Qingyun Yang , Christoph Federrath

Analyzing the properties of dust and its evolution in the early phases of star formation is crucial to put constraints on the collapse and accretion processes as well as on the pristine properties of planet-forming seeds. We analyze PdBI…

Astrophysics of Galaxies · Physics 2019-11-27 Maud Galametz , Anaelle J. Maury , Valeska Valdivia , Leonardo Testi , Arnaud Belloche , Philippe Andre

Volume and column density PDFs in molecular clouds are important diagnostics for understanding their general structure. We developed a novel approach to trace the cloud structure by varying the lower PDF cut-off and exploring a suggested…

Solar and Stellar Astrophysics · Physics 2013-08-02 Orlin Stanchev , Sava Donkov , Todor V. Veltchev , Rahul Shetty

(Abridged) The physical structure of deeply-embedded low-mass protostars (Class 0) on scales of less than 300 AU is still poorly constrained. Determining this is crucial for understanding the physical and chemical evolution from cores to…

Solar and Stellar Astrophysics · Physics 2016-05-04 M. V. Persson , D. Harsono , J. J. Tobin , E. F. van Dishoeck , J. K. Jørgensen , N. Murillo , S. -P. Lai

Understanding the formation mechanisms of protoplanetary disks and multiple systems, and their pristine properties, is a key question for modern astrophysics. The properties of the youngest disks, embedded in rotating infalling protostellar…

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