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We present an optical/near-IR survey of 11 variable young stars (EXors and EXor candidates) aimed at deriving and monitoring their accretion properties. About 30 optical and near-infrared spectra ($\Re$ $\sim$ 1500-2000) were collected…

Solar and Stellar Astrophysics · Physics 2022-04-27 T. Giannini , A. Giunta , M. Gangi , R. Carini , D. Lorenzetti , S. Antoniucci , A. Caratti o Garatti , L. Cassarà , B. Nisini , A. Rossi , V. Testa , F. Vitali

High spatial resolution CO observations of mid-inclination (30-75{\deg}) protoplanetary disks offer an opportunity to study the vertical distribution of CO emission and temperature. The asymmetry of line emission relative to the disk major…

The condensation fronts (snow lines) of H2O, CO and other abundant volatiles in the midplane of a protoplanetary disk affect several aspects of planet formation. Locating the CO snow line, where the CO gas column density is expected to drop…

We present ALMA CO(2-1) observations toward a massive infrared dark cloud G28.37+0.07. The ALMA data reveal numerous molecular (CO) outflows with a wide range of sizes throughout the cloud. Sixty-two 1.3 mm continuum cores were identified…

Astrophysics of Galaxies · Physics 2019-04-03 Shuo Kong , Héctor G. Arce , María José Maureira , Paola Caselli , Jonathan C. Tan , Francesco Fontani

Submillimeter/millimeter observations of dusty star-forming galaxies with the Atacama Large Millimeter/submillimeter Array (ALMA) have shown that dust continuum emission generally occurs in compact regions smaller than the stellar…

We have carried out a near-infrared imaging survey of luminous young stellar outflow candidates using the United Kingdom Infrared Telescope. Observations were obtained in the broad band K (2.2 mu) and through narrow band filters at the…

Solar and Stellar Astrophysics · Physics 2015-05-18 Watson P. Varricatt , Christopher J. Davis , Suzanne Ramsay , Stephen P. Todd

We present new infrared, submillimeter, and millimeter observations of the dense core L673-7 and report the discovery of a low-luminosity, embedded Class 0 protostar driving a molecular outflow. L673-7 is seen in absorption against the…

Astrophysics of Galaxies · Physics 2015-05-19 Michael M. Dunham , Neal J. Evans , Tyler L. Bourke , Philip C. Myers , Tracy L. Huard , Amelia M. Stutz

We present evolutionary models for young low mass stars and brown dwarfs taking into account episodic phases of accretion at early stages of the evolution, a scenario supported by recent large surveys of embedded protostars. An evolution…

Solar and Stellar Astrophysics · Physics 2015-05-13 I. Baraffe , G. Chabrier , J. Gallardo

Context: Gas accretion flows transport material from the cloud core onto the protostar. In multiple protostellar systems, it is not clear if the delivery mechanism is preferential or evenly distributed among the components. Aims: Gas…

Astrophysics of Galaxies · Physics 2022-02-02 Nadia M. Murillo , Ewine F. van Dishoeck , Alvaro Hacar , Daniel Harsono , Jes K. Jørgensen

We present Atacama Large Millimeter Array (ALMA) Cycle-0 observations of the CO J = 6-5 line in the advanced galaxy merger Arp 220. This line traces warm molecular gas, which dominates the total CO luminosity. The CO emission from the two…

Astrophysics of Galaxies · Physics 2015-06-11 Naseem Rangwala , Philip Maloney , Christine Wilson , Jason Glenn , Julia Kamenetzky , Luigi Spinoglio

Observations of submillimeter lines of CO (up to J=6-5), HCO+, HCN (up to J=4-3) and their isotopes from circumstellar disks around low mass pre-main sequence stars are presented. The different line ratios and optical depths indicate that…

We present Very Large Array (VLA) high resolution observations of the NH3(1,1) and NH3(2,2) molecular transitions towards the high mass star forming region AFGL 437. Our aim was to investigate if the poorly collimated CO molecular outflow…

Astrophysics of Galaxies · Physics 2015-06-03 G. Manjarrez , J. F. Gomez , I. de Gregorio-Monsalvo

We used the Submillimeter Array (SMA) to image 860 micron continuum and CO(3-2) line emission in the ultraluminous merging galaxy Arp 220, achieving a resolution of 0.23" (80 pc) for the continuum and 0.33" (120 pc) for the line. The CO…

[abridged] The enhanced degrees of deuterium fractionation observed in envelopes around protostars demonstrate the importance of chemistry at low temperatures, relevant in pre- and protostellar cores. formaldehyde is an important species in…

We present new results on CO depletion in a sample of nearby pre-stellar cores, based on observations of the millimeter C17O and C18O lines and the 1.3 mm dust emission with the IRAM 30m telescope. In most cases, the distribution of CO is…

We report serendipitous detections of line emission with ALMA in band 3, 6, and 7 in the central parsec of the Galactic center at an up to now highest resolution (<0.7''). Among the highlights are the very first and highly resolved images…

We report on interferometric observations of a face-on accretion system around the High-Mass young stellar object, G353.273+0.641. The innermost accretion system of 100 au radius was resolved in a 45 GHz continuum image taken with the…

The variability of submillimeter emission provides a useful tool to probe the accretion physics in low-luminosity active galactic nuclei. We accumulate four years of observations using Submillimeter Array for Centaurus A, NGC 4374, NGC…

High Energy Astrophysical Phenomena · Physics 2023-07-12 Bo-Yan Chen , Geoffrey C. Bower , Jason Dexter , Sera Markoff , Anthony Ridenour , Mark A. Gurwell , Ramprasad Rao , Sofia H. J. Wallström