Star-forming Regions in the Irregular Galaxy NGC 4449: Determination of Their Integrated Parameters

2000 ◽  
Vol 119 (5) ◽  
pp. 2166-2182 ◽  
Author(s):  
Oriol Fuentes-Masip ◽  
Héctor O. Castañeda ◽  
Casiana Muñoz-Tuñón
Keyword(s):  
Irregular Galaxy ◽  
Star Forming ◽  
Star Forming Regions

AMBIPOLAR DIFFUSION AND TURBULENT MAGNETIC FIELDS IN MOLECULAR CLOUDS

2011 ◽  
Vol 26 (04) ◽  
pp. 235-249 ◽  
Author(s):  
MARTIN HOUDE ◽  
TALAYEH HEZAREH ◽  
HUA-BAI LI ◽  
THOMAS G. PHILLIPS
Keyword(s):  
Magnetic Fields ◽  
Molecular Clouds ◽  
Ambipolar Diffusion ◽  
Star Forming ◽  
Star Forming Regions ◽  
Spin Interactions ◽  
Line Narrowing ◽  
Weakly Ionized ◽  
Novel Method

We review the introduction and development of a novel method for the characterization of magnetic fields in star-forming regions. The technique is based on the comparison of spectral line profiles from coexistent neutral and ion molecular species commonly detected in molecular clouds, sites of star formation. Unlike other methods used to study magnetic fields in the cold interstellar medium, this ion/neutral technique is not based on spin interactions with the field. Instead, it relies on and takes advantage of the strong cyclotron coupling between the ions and magnetic fields, thus exposing what is probably the clearest observational manifestation of magnetic fields in the cold, weakly ionized gas that characterizes the interior of molecular clouds. We will show how recent development and modeling of the ensuing ion line narrowing effect leads to a determination of the ambipolar diffusion scale involving the turbulent component of magnetic fields in star-forming regions, as well as the strength of the ordered component of the magnetic field.

scholarly journals The Flying Saucer: Tomography of the thermal and density gas structure of an edge-on protoplanetary disk

2017 ◽  
Vol 607 ◽  
pp. A130 ◽  
Author(s):  
A. Dutrey ◽  
S. Guilloteau ◽  
V. Piétu ◽  
E. Chapillon ◽  
V. Wakelam ◽  
...  
Keyword(s):  
Thermal Structure ◽  
Direct Determination ◽  
Molecular Data ◽  
Temperature Structure ◽  
Gas Temperature ◽  
Star Forming ◽  
Star Forming Regions ◽  
Flying Saucer ◽  
Grain Properties

Context. Determining the gas density and temperature structures of protoplanetary disks is a fundamental task in order to constrain planet formation theories. This is a challenging procedure and most determinations are based on model-dependent assumptions. Aims. We attempt a direct determination of the radial and vertical temperature structure of the Flying Saucer disk, thanks to its favorable inclination of 90 degrees. Methods. We present a method based on the tomographic study of an edge-on disk. Using ALMA, we observe at 0.5″ resolution the Flying Saucer in CO J = 2–1 and CS J = 5–4. This edge-on disk appears in silhouette against the CO J = 2–1 emission from background molecular clouds in ρ Oph. The combination of velocity gradients due to the Keplerian rotation of the disk and intensity variations in the CO background as a function of velocity provide a direct measure of the gas temperature as a function of radius and height above the disk mid-plane. Results. The overall thermal structure is consistent with model predictions, with a cold (<12−15 K) CO-depleted mid-plane and a warmer disk atmosphere. However, we find evidence for CO gas along the mid-plane beyond a radius of about 200 au, coincident with a change of grain properties. Such behavior is expected in the case of efficient rise of UV penetration re-heating the disk and thus allowing CO thermal desorption or favoring direct CO photo-desorption. CO is also detected at up to 3–4 scale heights, while CS is confined to around 1 scale height above the mid-plane. The limits of the method due to finite spatial and spectral resolutions are also discussed. Conclusions. This method appears to be a very promising way to determine the gas structure of planet-forming disks, provided that the molecular data have an angular resolution which is high enough, on the order of 0.3−0.1″ at the distance of the nearest star-forming regions.

scholarly journals VLBA DETERMINATION OF THE DISTANCE TO NEARBY STAR-FORMING REGIONS. IV. A PRELIMINARY DISTANCE TO THE PROTO-HERBIG AeBe STAR EC 95 IN THE SERPENS CORE

2010 ◽  
Vol 718 (2) ◽  
pp. 610-619 ◽  
Author(s):  
Sergio Dzib ◽  
Laurent Loinard ◽  
Amy J. Mioduszewski ◽  
Andrew F. Boden ◽  
Luis F. Rodríguez ◽  
...  
Keyword(s):  
Nearby Star ◽  
Star Forming ◽  
Star Forming Regions

scholarly journals UVIT Imaging of WLM: Demographics of Star-forming Regions in the Nearby Dwarf Irregular Galaxy

2018 ◽  
Vol 156 (3) ◽  
pp. 109 ◽  
Author(s):  
Chayan Mondal ◽  
Annapurni Subramaniam ◽  
Koshy George
Keyword(s):  
Irregular Galaxy ◽  
Star Forming ◽  
Star Forming Regions

scholarly journals VLBA DETERMINATION OF THE DISTANCE TO NEARBY STAR-FORMING REGIONS. VII. MONOCEROS R2

2016 ◽  
Vol 826 (2) ◽  
pp. 201 ◽  
Author(s):  
Sergio A. Dzib ◽  
Gisela N. Ortiz-León ◽  
Laurent Loinard ◽  
Amy J. Mioduszewski ◽  
Luis F. Rodríguez ◽  
...  
Keyword(s):  
Nearby Star ◽  
Star Forming ◽  
Star Forming Regions

scholarly journals Determination of kinematic distances of pre-main-sequence stars in star-forming regions

2009 ◽  
Vol 5 (S266) ◽  
pp. 395-398
Author(s):  
Phillip A. B. Galli ◽  
Ramachrisna Teixeira ◽  
Christine Ducourant ◽  
Claude Bertout
Keyword(s):  
Main Sequence ◽  
Young Stars ◽  
Formation Mechanisms ◽  
Main Sequence Stars ◽  
Star Forming ◽  
Know How ◽  
Star Forming Regions ◽  
Moving Groups ◽  
Kinematic Properties

AbstractMany studies of star-forming regions have been carried out since the discovery of compact Hii regions in the late 1960s. The kinematic properties of young stars in the nearest regions with ongoing and recent star formation provide essential tests of their formation mechanisms. The detection of coeval moving groups allows determination of individual distances through the convergent-point method. As a result, the main physical properties of these stars and their early evolutionary stages can be determined if we know how distant they are.

scholarly journals Abundance determination of multiple star-forming regions in the H ii galaxy SDSS J165712.75+321141.4

2011 ◽  
Vol 414 (1) ◽  
pp. 272-288 ◽  
Author(s):  
Guillermo F. Hägele ◽  
Rubén García-Benito ◽  
Enrique Pérez-Montero ◽  
Ángeles I. Díaz ◽  
Mónica V. Cardaci ◽  
...  
Keyword(s):  
Multiple Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Abundance Determination

scholarly journals VLBA Determination of the Distance to Nearby Star‐forming Regions. I. The Distance to T Tauri with 0.4% Accuracy

2007 ◽  
Vol 671 (1) ◽  
pp. 546-554 ◽  
Author(s):  
Laurent Loinard ◽  
Rosa M. Torres ◽  
Amy J. Mioduszewski ◽  
Luis F. Rodriguez ◽  
Rosa A. Gonzalez‐Lopezlira ◽  
...  
Keyword(s):  
Nearby Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
T Tauri
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