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Black hole accretion flows can be divided into two broad classes: cold and hot. Cold accretion flows, which consist of cool optically thick gas, are found at relatively high mass accretion rates. Prominent examples are the standard thin…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Feng Yuan , Ramesh Narayan

We present a 350 micron APEX/SABOCA map of IRAS 05399-0121/SMM 1, which is a dense double-core system in Orion B9. We combined these data with our previous LABOCA 870-micron data. The spatial resolution of the new SABOCA image, ~3400 AU, is…

Astrophysics of Galaxies · Physics 2015-06-15 Oskari Miettinen , Stella S. R. Offner

Massive infrared dark clouds (IRDCs) are considered to host the earliest stages of high-mass star formation. In particular, 70 $\mu$m dark IRDCs are the colder and more quiescent clouds. At a scale of about 5000 au using formaldehyde (H2CO)…

We explore the relationship between gas and dust in massive star-forming regions by comparing physical properties derived from each. We compare the temperatures and column densities in a massive star-forming Infrared Dark Cloud (IRDC,…

Astrophysics of Galaxies · Physics 2014-05-15 Cara Battersby , John Bally , Miranda Dunham , Adam Ginsburg , Steve Longmore , Jeremy Darling

We use high resolution cosmological hydrodynamical simulations to demonstrate that cold flow gas accretion, particularly along filaments, modifies the standard picture of gas accretion and cooling onto galaxy disks. In the standard picture,…

Astrophysics · Physics 2011-02-11 A. M. Brooks , F. Governato , T. Quinn , C. B. Brook , J. Wadsley

Abundance of chemical elements in the stars provides important clues regarding galaxy formation. The most powerful diagnostics is the relative abundance of {\alpha}-elements (O, Mg, Si, S, Ca, and Ti) with respect to iron (Fe),…

Astrophysics of Galaxies · Physics 2018-09-10 Masafumi Noguchi

We study a sample of 44 low-luminosity radio-loud AGN, which represent a range of nuclear radio-power spanning 5 orders of magnitude, to unveil the accretion mechanism in these galaxies. We estimate the accretion rate of gas associated with…

Astrophysics · Physics 2009-11-13 Barbara Balmaverde , Ranieri D. Baldi , Alessandro Capetti

The protostar IRAS 15398-3359 is associated with a bipolar molecular outflow ejected in an nearly northeast-southwest (NE-SW) direction which has been extensively studied. It has been suggested previous episodic accretion events by this…

Solar and Stellar Astrophysics · Physics 2024-06-12 E. Guzmán Ccolque , M. Fernández López , M. M. Vazzano , I. de Gregorio , A. Plunkett , A. Santamaría-Miranda

(Abridged) Through spectrally unresolved observations of high-J CO transitions, Herschel-PACS has revealed large reservoirs of warm (300 K) and hot (700 K) molecular gas around low-mass protostars. We aim to shed light on the excitation and…

The study of multiple molecular spectral lines in gas infalling sources can provide the physical and chemical properties of these sources and help us estimate their evolutionary stages. We report line detections within the 3 mm band using…

Astrophysics of Galaxies · Physics 2025-04-09 Yang Yang , Xi Chen , ZhiBo Jiang , Zhiwei Chen , Shuling Yu , Jun Li

The high-velocity clouds (HVCs) in the outer Milky Way at $20^{\circ} < l < 190^{\circ}$ have similar spatial locations, metallicities, and kinematics. Moreover, their locations and kinematics are coincident with several extraplanar stellar…

Astrophysics of Galaxies · Physics 2022-10-21 Todd M. Tripp

Until now the known sources in the Galactic center with sufficiently smooth spectra and of sufficient brightness to be suitable for high resolution infrared absorption spectroscopy of interstellar gas occupied a narrow range of longitudes,…

Astrophysics of Galaxies · Physics 2015-05-14 T. R. Geballe , T. Oka

The hypothesized supermassive black hole in the nucleus of M31 (which we shall hereafter call M31*) has many features in common with Sgr A* at the Galactic Center, yet they differ in several significant and important ways. Though M31* is…

Astrophysics · Physics 2016-08-30 Siming Liu , Fulvio Melia

It remains a key challenge to establish the molecular content of different components of low-mass protostars, like their envelopes and disks, and how this depends on the evolutionary stage and/or environment of the young stars. Observations…

Solar and Stellar Astrophysics · Physics 2015-05-30 Jes K. Jorgensen , Tyler L. Bourke , Quang Nguyen Luong , Shigehisa Takakuwa

We study the gas distribution in the Milky Way and Andromeda using a constrained cosmological simulation of the Local Group (LG) within the context of the CLUES (Constrained Local UniversE Simulations) project. We analyse the properties of…

Transferring a significant fraction of the magnetic flux from a dense cloud core is essential in the star formation process. A ring-like structure produced by magnetic flux loss has been predicted theoretically, but no observational…

While unbiased surveys observable from ground-based telescopes have previously been obtained towards several high mass protostars, very little exists on low mass protostars. To fill up this gap, we carried out a complete spectral survey of…

The identification of the main sulfur reservoir on its way from the diffuse interstellar medium to the cold dense star-forming cores and eventually to protostars is a long-standing problem. Despite sulfur's astrochemical relevance, the…

Astrophysics of Galaxies · Physics 2023-04-12 Tanya Kushwahaa , Maria N. Drozdovskaya , Łukasz Tychoniec , Benoît Tabone