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A long-standing problem in low-mass star formation is the "luminosity problem," whereby protostars are underluminous compared to the accretion luminosity expected both from theoretical collapse calculations and arguments based on the…

Astrophysics of Galaxies · Physics 2014-11-20 Michael M. Dunham , Neal J. Evans , Susan Terebey , Cornelis P. Dullemond , Chadwick H. Young

Aims. Studying protostellar objects in their earliest stages, particularly during the Class 0 phase, provides key insight into the beginnings of planet formation and dust evolution. Disentangling the various components, however, is…

We present a survey of the formaldehyde emission in a sample of eight Class 0 protostars obtained with the IRAM and JCMT telescopes. The data have been analyzed with three different methods with increasing level of sophistication. We first…

(Abridged) We use optical spectroscopy to investigate the disk, wind, and accretion during the 2008 ZCMa NW outburst. Over 1000 optical emission lines reveal accretion, a variable, multi-component wind, and double-peaked lines of disk…

Solar and Stellar Astrophysics · Physics 2020-10-28 A. Sicilia-Aguilar , J. Bouvier , C. Dougados , K. Grankin , J. -F. Donati

We observed the W51 high-mass star-forming complex with ALMA's longest-baseline configurations, achieving an angular resolution of $\sim$20 milliarcseconds, corresponding to a linear resolution of $\sim$100 au at $D_{\mathrm{W51}}=5.4$ kpc.…

Astrophysics of Galaxies · Physics 2020-12-23 Ciriaco Goddi , Adam Ginsburg , Luke Maud , Qizhou Zhang , Luis Zapata

We present a survey toward 16 Low Luminosity Objects (LLOs with an internal luminosity, Lint, lower than 0.2 Lsun) with N2H+ (1-0), N2H+ (3-2), N2D+ (3-2), HCO+ (3-2) and HCN (3-2) using the Arizona Radio Observatory Kitt Peak 12m Telescope…

Astrophysics of Galaxies · Physics 2015-06-24 Tien-Hao Hsieh , Shih-Ping Lai , Arnaud Belloche , Friedrich Wyrowski , Chao-Ling Hung

Studying the physical and chemical properties of cold and dense molecular clouds is crucial for the understanding of how stars form. Under the typical conditions of infrared dark clouds, CO is removed from the gas phase and trapped on to…

High-amplitude variability in Young Stellar Objects (YSOs) is usually associated with episodic accretion events. It has not been observed so far in massive YSOs. Here, the high-amplitude variable star sample of ContrerasPe\~{n}a et…

Solar and Stellar Astrophysics · Physics 2016-12-14 M. S. N. Kumar , C. Contreras-Pena , P. W. Lucas , M. A. Thompson

We present a study of accretion in a sample of 45 young, low mass objects in a variety of star forming regions and young associations, about half of which are likely substellar. Based primarily on the presence of broad, asymmetric Halpha…

Astrophysics · Physics 2009-07-09 James Muzerolle , Lynne Hillenbrand , Nuria Calvet , Cesar Briceno , Lee Hartmann

We present the detection of multiple CO line transitions with ALMA in a few tens of infrared-selected galaxies on and above the main sequence at z=1.1-1.7. We reliably detected the emission of CO(5-4), CO(2-1), and CO(7-6)+[CI](2-1) in 50,…

Evidence for a large scale flow of low density gas onto the Cepheus A young stellar cluster is presented. Observations of K-band near-infrared and multi-transition CS and N2H+ millimeter line emission are shown in relation to a…

Astrophysics · Physics 2009-11-10 Sandrine Bottinelli , Jonathan P. Williams

We report new, $\sim$1000 AU spatial resolution observations of 225 GHz dust continuum emission towards the OB cluster-forming molecular clump G33.92+0.11. On parsec scales, this molecular clump presents a morphology with several arm-like…

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of molecular line emission from d216-0939, one of the largest and most massive protoplanetary disks in the Orion Nebula Cluster (ONC). We model the spectrally…

We present an analysis of the dust attenuation of star forming galaxies at $z=2.5-4.0$ through the relationship between the UV spectral slope ($\beta$), stellar mass ($M_{\ast}$) and the infrared excess (IRX$=L_{\rm{IR}}/L_{\rm{UV}}$) based…

We present a study of chemistry toward 294 dense cores in 12 molecular clumps using the data obtained from the ALMA Survey of 70 $\mu \rm m$ dark High-mass clumps in Early Stages (ASHES). We identified 97 protostellar cores and 197…

We acquired ALMA ground state absorption profiles of HCO+ and other molecules toward 33 extragalactic continuum sources seen toward the Galactic anticenter, deriving N(H2) = N(HCO+)/3x10^{-9}. We observed J=1-0 CO emission with the IRAM 30m…

Astrophysics of Galaxies · Physics 2023-07-19 Harvey Liszt , Maryvonne Gerin

We present new observations of the CB130 region, composed of three separate cores. Using the \textit{Spitzer Space Telescope} we detected a Class 0 and a Class II object in one of these, CB130-1. The observed photometric data from…

We used the NRAO Very Large Array to search for 3.6 cm continuum emission from embedded protostars in a sample of 8 nearby ``starless'' cores that show spectroscopic evidence for infalling motions in molecular emission lines. We detect a…

Astrophysics · Physics 2009-11-07 D. W. A. Harvey , D. J. Wilner , J. Di Francesco , C. -W. Lee , P. C. Myers , J. P. Williams

(Abridged) We aim to determine the degrees of CO depletion, deuterium fractionation, and ionisation in a sample of seven massive clumps associated with IRDCs. The APEX telescope was used to observe the C17O(2-1), H13CO+(3-2), DCO+(3-2),…

Astrophysics of Galaxies · Physics 2015-05-30 Oskari Miettinen , Martin Hennemann , Hendrik Linz

Context. Acetone (CH3COCH3) is a carbonyl-bearing complex organic molecule, yet interstellar observations of acetone remain limited. Studying the formation and distribution of CH3COCH3 in the interstellar medium can provide valuable…