Scott Schnee

THE EFFECT OF NOISE ON THE DUST TEMPERATURE-SPECTRAL INDEX CORRELATION

We investigate how uncertainties in flux measurements affect the results from modified blackbody spectral energy distribution (SED) fits. We show that an inverse correlation between the dust temperature T and spectral index β naturally arises from least-squares fits due to the uncertainties, even for sources with a single T and β. Fitting SEDs to noisy fluxes solely in the Rayleigh-Jeans regime produces unreliable T and β estimates. Thus, for long wavelength observations (λ 200 μm), or for warm sources (T 60 K), it becomes difficult to distinguish sources with different temperatures. We assess the role of noise in recent observational results that indicate an inverse and continuously varying T-β relation. Though an inverse and continuous T-β correlation may be a physical property of dust in the interstellar medium, we find that the observed inverse correlation may be primarily due to noise.

THE ENIGMATIC CORE L1451-mm: A FIRST HYDROSTATIC CORE? OR A HIDDEN VeLLO?

We present the detection of a dust continuum source at 3 mm (CARMA) and 1.3 mm (Submillimeter Array, SMA), and 12CO (2-1) emission (SMA) toward the L1451-mm dense core. These detections suggest a compact object and an outflow where no point source at mid-infrared wavelengths is detected using Spitzer. An upper limit for the dense core bolometric luminosity of 0.05 L # is obtained. By modeling the broadband spectral energy distribution and the continuum interferometric visibilities simultaneously, we confirm that a central source of heating is needed to explain the observations. This modeling also shows that the data can be well fitted by a dense core with a young stellar object (YSO) and a disk, or by a dense core with a central first hydrostatic core (FHSC). Unfortunately, we are not able to decide between these two models, which produce similar fits. We also detect 12CO (2-1) emission with redshifted and blueshifted emission suggesting the presence of a slow and poorly collimated outflow, in opposition to what is usually found toward YSOs but in agreement with prediction from simulations of an FHSC. This presents the best candidate, so far, for an FHSC, an object that has been identified in simulations of collapsing dense cores. Whatever the true nature of the central object in L1451-mm, this core presents an excellent laboratory to study the earliest phases of low-mass star formation. Based on observations carried out with the IRAM 30 m Telescope, the Submillimeter Array, and CARMA. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. Support for CARMA construction was derived from the states of California, Illinois, and Maryland, the James S. McDonnell Foundation, the Gordon and Betty Moore Foundation, the Kenneth T. and Eileen L. Norris Foundation, the University of Chicago, the Associates of the California Institute of Technology, and the National Science Foundation. Ongoing CARMA development and operations are supported by the National Science Foundation under a cooperative agreement and by the CARMA partner universities.

DETECTION OF A BIPOLAR MOLECULAR OUTFLOW DRIVEN BY A CANDIDATE FIRST HYDROSTATIC CORE

We present new 230 GHz Submillimeter Array observations of the candidate first hydrostatic core Per-Bolo 58. We report the detection of a 1.3 mm continuum source and a bipolar molecular outflow, both centered on the position of the candidate first hydrostatic core. The continuum detection has a total flux density of 26.6 ± 4.0 mJy, from which we calculate a total (gas and dust) mass of 0.11 ± 0.05 Mand a mean number density of 2.0 ± 1.6 × 10 7 cm −3 . There is some evidence for the existence of an unresolved component in the continuum detection, but longer-baseline observations are required in order to confirm the presence of this component and determine whether its origin lies in a circumstellar disk or in the dense inner envelope. The bipolar molecular outflow is observed along a nearly due east-west axis. The outflow is slow (characteristic velocity of 2.9 km s −1 ), shows a jet-like morphology (opening semi-angles ∼8 ◦ for both lobes), and extends to the edges of the primary beam. We calculate the kinematic and dynamic properties of the outflow in the standard manner and compare them to several other protostars and candidate first hydrostatic cores with similarly low luminosities. We discuss the evidence both in support of and against the possibility that Per-Bolo 58 is a first hydrostatic core, and we outline future work needed to further evaluate the evolutionary status of this object.

A Sub-arcsecond Survey Toward Class 0 Protostars in Perseus : Searching for Signatures of Protostellar Disks

We present a CARMA 1.3 mm continuum survey toward 9 Class 0 protostars in the Perseus molecular cloud at

The Dust Emissivity Spectral Index in the Starless Core TMC-1C

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TMC-1C: An Accreting Starless Core

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The complete nature of the warm dust shell in perseus

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DUST EMISSION FROM THE PERSEUS MOLECULAR CLOUD

(70 AU) resolution. This study approximately doubles the number of Class 0 protostars observed with spatial resolutions

HOW STARLESS ARE STARLESS CORES

100 AU around 2 sources (L1448 IRS2 and Per-emb-14) and these sources may be strong disk candidates. Marginally-resolved structures with position angles within 30