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Related papers: DR 21 South Filament: a Parsec-sized Dense Gas Acc…

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Damped Lyman-alpha systems (DLAs) seen in the spectra of high-z QSOs allow us to probe the physical conditions in protogalaxies. Our understanding of physical conditions in DLAs at high-z is primarily based on the absorption lines of H_2…

Cosmology and Nongalactic Astrophysics · Physics 2009-02-19 N. Gupta , R. Srianand , P. Petitjean , P. Noterdaeme , D. J. Saikia

We investigate the practice of assigning high spin temperatures to damped Lyman-alpha absorption systems (DLAs) not detected in HI 21-cm absorption. In particular, Kanekar & Chengaulr (2003) have attributed the mix of 21-cm detections and…

Astrophysics · Physics 2009-11-10 S. J. Curran , M. T. Murphy , Y. M. Pihlstroem , J. K. Webb , C. R. Purcell

The initial conditions of massive star and star cluster formation are expected to be cold, dense and high column density regions of the interstellar medium, which can reveal themselves via near, mid and even far-infrared absorption as…

It has recently been shown that the abundance of cold neutral gas may follow a similar evolution as the star formation history. This is physically motivated, since stars form out of this component of the neutral gas and if the case, would…

Astrophysics of Galaxies · Physics 2018-12-05 S. J. Curran

We present new 0.6 - 4 $\mu$m imaging of the SR 21 transition disk from Keck/NIRC2 and Magellan/MagAO. The protoplanetary disk around SR 21 has a large (~ 30 - 40 AU) clearing first inferred from its spectral energy distribution and later…

We quantify the gas flows from a scale of up to several parsecs down to the sub-parsec scale along filamentary structures in the three high-mass star-forming regions G75.78, IRAS21078+5211 and NGC7538 with data obtained from the IRAM 30 m…

We present Giant Metrewave Radio Telescope HI 21cm absorption observations, of candidate and confirmed damped Lyman-$\alpha$ systems (DLAS). The derived spin temperatures (T_s) are in all cases $\sim 1000$ K or higher. We have also collated…

Astrophysics · Physics 2015-06-24 Jayaram N Chengalur , Nissim Kanekar

We present atmospheric parameters for 51 nearby FG dwarfs uniformly distributed over the -2.60 < [Fe/H] < +0.20 metallicity range that is suitable for the Galactic chemical evolution research. Lines of iron, Fe I and Fe II, were used to…

Solar and Stellar Astrophysics · Physics 2015-08-06 T. Sitnova , G. Zhao , L. Mashonkina , Y. Q. Chen , F. Liu , Yu. Pakhomov , K. Tan , M. Bolte , S. Alexeeva , F. Grupp , J. -R. Shi , H. -W. Zhang

The non-thermal filament (NTF) radio structures clustered within a few hundred parsecs of the Galactic Center (GC) are apparently unique to this region of the Galaxy. Recent radio images of the GC using MeerKAT at 1 GHz have revealed a…

Astrophysics of Galaxies · Physics 2022-12-21 Dylan M. Paré , Cornelia C. Lang , Mark R. Morris

We compare the gas distribution, kinematics and the current star formation in a sample of 10 very faint (-13.37 < M_B < -9.55) dwarf galaxies. For 5 of these galaxies we present fresh, high sensitivity, GMRT HI 21cm observations. For all…

The interstellar medium of galaxies, with temperatures reaching several million degrees, provides a pivotal perspective for understanding the physical and chemical properties of star formation, galactic evolution, and their associated…

Astrophysics of Galaxies · Physics 2025-06-24 Chunyi Zhang , Junfeng Wang

Filamentary structures are widely observed in molecular clouds, yet most filament observations are biased toward case studies and small samples; a uniform census within a single giant molecular cloud is still missing. We do a complete…

Astrophysics of Galaxies · Physics 2026-03-18 Yingxi Li , Keping Qiu

Dense filaments are believed to be representative of the initial conditions of star formation in molecular clouds. We have used the MIRI instrument on JWST to image the massive filament NGC6334M at d~1.3 kpc with unprecedented resolution…

Over the last 3 yrs, the Galactic center (GC) region has been monitored with the Chandra X-Ray Observatory. With 11 Chandra observations through 2002 June, the total effective exposure reaches ~590 ks, providing significant photon…

The fragmentation process in massive star-forming regions is one of the contemporary problems in astrophysics, and several physical processes have been proposed to control the fragmentation including turbulence, magnetic field, rotation,…

Astrophysics of Galaxies · Physics 2021-12-22 Mengyao Tang , Aina Palau , Luis A. Zapata , Sheng-Li Qin

Most of the baryons in the Universe are thought to be contained within filaments of galaxies, but as yet, no single study has published the observed properties of a large sample of known filaments to determine typical physical…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Amelia Fraser-McKelvie , Kevin A. Pimbblet , Jasmina S. Lazendic

Filamentary flows toward the centre of molecular clouds have been recognized as a crucial process in the formation and evolution of stellar clusters. In this paper, we present a comprehensive observational study that investigates the gas…

Astrophysics of Galaxies · Physics 2024-01-12 Vineet Rawat , M. R. Samal , D. L. Walker , D. K. Ojha , A. Tej , A. Zavagno , C. P. Zhang , Davide Elia , S. Dutta , J. Jose , C. Eswaraiah , E. Sharma

The 500 central pc of the Galaxy (hereafter GC) exhibit a widespread gas component with a kinetic temperature of 100-200 K. The bulk of this gas is not associated to the well-known thermal radio continuum or far infrared sources like Sgr A…

Astrophysics · Physics 2009-11-10 N. J Rodriguez-Fernandez , J. Martin-Pintado , A. Fuente , T. L. Wilson

Deep imaging of the Sgr A complex at 6 cm wavelength with the B and C configurations of the Karl G. Jansky VLA has revealed a new population of faint radio filaments. Like their brighter counterparts that have been observed throughout the…

Astrophysics of Galaxies · Physics 2015-06-18 Mark Morris , Jun-Hui Zhao , W. M. Goss

We study a fragment of a large quiescent filament observed on May 29, 2017 by the Interferometric BIdimensional Spectropolarimeter (IBIS) mounted at the Dunn Solar Telescope. We focus on its quiescent stage prior to its eruption. We analyse…

Solar and Stellar Astrophysics · Physics 2019-11-13 P. Schwartz , S. Gunar , J. M. Jenkins , D. M. Long , P. Heinzel , D. P. Choudhary