scholarly journals The relationship between mid-infrared and sub-millimetre variability of deeply embedded protostars

2020 ◽  
Vol 495 (4) ◽  
pp. 3614-3635 ◽  
Author(s):  
Carlos Contreras Peña ◽  
Doug Johnstone ◽  
Giseon Baek ◽  
Gregory J Herczeg ◽  
Steve Mairs ◽  
...  
Keyword(s):  
Young Stellar Objects ◽  
Time Variability ◽  
Wide Field ◽  
Stellar Objects ◽  
Mid Infrared ◽  
James Clerk Maxwell ◽  
Secular Variability ◽  
The Relationship ◽  
Exact Scaling ◽  
Infrared Survey

ABSTRACT We study the relationship between the mid-infrared (mid-IR) and sub-millimetre (sub-mm) variability of deeply embedded protostars using the multi-epoch data from the Wide-field Infrared Survey Explorer (WISE/NEOWISE) and the ongoing James Clerk Maxwell Telescope (JCMT) Transient Survey. Our search for signs of stochastic (random) and/or secular (roughly monotonic in time) variability in a sample of 59 young stellar objects (YSOs) revealed that 35 are variable in at least one of the two surveys. This variability is dominated by secular changes. Of those objects with secular variability, 14 objects ($22{{\ \rm per\ cent}}$ of the sample) show correlated secular variability over mid-IR and sub-mm wavelengths. Variable accretion is the likely mechanism responsible for this type of variability. Fluxes of YSOs that vary in both wavelengths follow a relation of log10F4.6(t) = ηlog10F850(t) between the mid-IR and sub-mm, with η = 5.53 ± 0.29. This relationship arises from the fact that sub-mm fluxes respond to the dust temperature in the larger envelope whereas the mid-IR emissivity is more directly proportional to the accretion luminosity. The exact scaling relation, however, depends on the structure of the envelope, the importance of viscous heating in the disc, and dust opacity laws.

scholarly journals The WISE Census of Young Stellar Objects and Clusters in Canis Major

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
W. J. Fischer ◽  
D. L. Padgett ◽  
K. R. Stapelfeldt
Keyword(s):  
Molecular Clouds ◽  
Photometric Data ◽  
Young Stellar Objects ◽  
Wide Field ◽  
Stellar Objects ◽  
Infrared Survey

AbstractThe photometric data returned by WISE, the Wide-field Infrared Survey Explorer, can be used to search the sky for young stellar objects (YSOs) away from the molecular clouds studied in detail by Spitzer and Herschel. We present updated results for a 100 deg2 region centered on Canis Major, including a look at the clustering properties of YSOs in the region.

scholarly journals Triggered star formation in a cometary atomic/molecular cloud in the Cep OB3 association

2019 ◽  
Vol 489 (4) ◽  
pp. 4809-4816 ◽  
Author(s):  
Brandon Marshall ◽  
C R Kerton
Keyword(s):  
Star Formation ◽  
Galactic Plane ◽  
Initial Conditions ◽  
Young Stellar Objects ◽  
Wide Field ◽  
Infrared Source ◽  
Stellar Objects ◽  
Iras Source ◽  
Infrared Observations ◽  
Infrared Survey

ABSTRACT We present a study of a small atomic/molecular cometary cloud associated with the infrared source IRAS 23153+6938. The cloud is located 70 pc from the massive O-type stars in the Cepheus OB3 association, and is very likely an excellent example of triggered star formation via radiation-driven implosion (RDI). The cloud was studied using $\rm{H\,\small{I}}$ and 12CO data from the Canadian Galactic Plane Survey (CGPS) and infrared observations from the Wide-field Infrared Survey Explorer (WISE) telescope. The molecular mass is approximately MH2 = 350 ± 45 M$\odot$, and we find that the single IRAS source is actually the centre of a small cluster of class I and class II young stellar objects (YSOs). To compare with theory, we make reasonable estimates for the cometary cloud’s initial conditions and find that the cloud is located within the correct theoretical phase space for RDI to occur. In addition, both the morphology of the cloud and the location of different YSO classes relative to the cloud match what would be expected for RDI. We conclude that RDI is the most likely explanation for star formation within the cloud, and we suggest that similar studies of molecular clouds associated with nearby OB associations may be able to identify comparable examples.

scholarly journals WIDE-FIELD INFRARED SURVEY EXPLORER OBSERVATIONS OF YOUNG STELLAR OBJECTS IN THE WESTERN CIRCINUS MOLECULAR CLOUD

2011 ◽  
Vol 733 (1) ◽  
pp. L2 ◽  
Author(s):  
Wilson M. Liu ◽  
Deborah L. Padgett ◽  
David Leisawitz ◽  
Sergio Fajardo-Acosta ◽  
Xavier P. Koenig
Keyword(s):  
Molecular Cloud ◽  
Young Stellar Objects ◽  
Wide Field ◽  
Stellar Objects ◽  
Infrared Survey

scholarly journals WIDE-FIELD INFRARED SURVEY EXPLOREROBSERVATIONS OF YOUNG STELLAR OBJECTS IN THE LYNDS 1509 DARK CLOUD IN AURIGA

2014 ◽  
Vol 147 (6) ◽  
pp. 133 ◽  
Author(s):  
Wilson M. Liu ◽  
Deborah L. Padgett ◽  
Susan Terebey ◽  
John Angione ◽  
Luisa M. Rebull ◽  
...  
Keyword(s):  
Young Stellar Objects ◽  
Wide Field ◽  
Dark Cloud ◽  
Stellar Objects ◽  
Infrared Survey

scholarly journals The WISE Census of Young Stellar Objects in Canis Major

2015 ◽  
Vol 10 (S314) ◽  
pp. 63-64
Author(s):  
W. J. Fischer ◽  
D. L. Padgett ◽  
K. R. Stapelfeldt
Keyword(s):  
Molecular Clouds ◽  
Young Stellar Objects ◽  
Wide Field ◽  
Spitzer Space Telescope ◽  
Stellar Objects ◽  
Space Telescope ◽  
Infrared Survey

AbstractWhile searches for young stellar objects (YSOs) with the Spitzer Space Telescope focused on known molecular clouds, photometry from the Wide-field Infrared Survey Explorer (WISE) can be used to extend the search to the entire sky. As a precursor to more expansive searches, we present results for a 100 deg2 region centered on the Canis Major clouds.

scholarly journals Identification of Young Stellar Object candidates in the Gaia DR2 x AllWISE catalogue with machine learning methods

2019 ◽  
Vol 487 (2) ◽  
pp. 2522-2537 ◽  
Author(s):  
G Marton ◽  
P Ábrahám ◽  
E Szegedi-Elek ◽  
J Varga ◽  
M Kun ◽  
...  
Keyword(s):  
Machine Learning ◽  
3D Structure ◽  
Physical Nature ◽  
Machine Learning Techniques ◽  
Young Stellar Objects ◽  
Support Vector ◽  
Wide Field ◽  
Stellar Objects ◽  
Star Forming ◽  
Gaia Dr2

ABSTRACT The second Gaia Data Release (DR2) contains astrometric and photometric data for more than 1.6 billion objects with mean Gaia G magnitude <20.7, including many Young Stellar Objects (YSOs) in different evolutionary stages. In order to explore the YSO population of the Milky Way, we combined the Gaia DR2 data base with Wide-field Infrared Survey Explorer (WISE) and Planck measurements and made an all-sky probabilistic catalogue of YSOs using machine learning techniques, such as Support Vector Machines, Random Forests, or Neural Networks. Our input catalogue contains 103 million objects from the DR2xAllWISE cross-match table. We classified each object into four main classes: YSOs, extragalactic objects, main-sequence stars, and evolved stars. At a 90 per cent probability threshold, we identified 1 129 295 YSO candidates. To demonstrate the quality and potential of our YSO catalogue, here we present two applications of it. (1) We explore the 3D structure of the Orion A star-forming complex and show that the spatial distribution of the YSOs classified by our procedure is in agreement with recent results from the literature. (2) We use our catalogue to classify published Gaia Science Alerts. As Gaia measures the sources at multiple epochs, it can efficiently discover transient events, including sudden brightness changes of YSOs caused by dynamic processes of their circumstellar disc. However, in many cases the physical nature of the published alert sources are not known. A cross-check with our new catalogue shows that about 30 per cent more of the published Gaia alerts can most likely be attributed to YSO activity. The catalogue can be also useful to identify YSOs among future Gaia alerts.

scholarly journals Kinematics around the B335 protostar down to au scales

2019 ◽  
Vol 631 ◽  
pp. A64 ◽  
Author(s):  
Per Bjerkeli ◽  
Jon P. Ramsey ◽  
Daniel Harsono ◽  
Hannah Calcutt ◽  
Lars E. Kristensen ◽  
...  
Keyword(s):  
Morphological Properties ◽  
Young Stellar Objects ◽  
Continuum Emission ◽  
Small Scale ◽  
Short Baseline ◽  
Stellar Objects ◽  
Spatially Resolved ◽  
Long Baseline ◽  
The Relationship ◽  
The Continuum

Context. The relationship between outflow launching and the formation of accretion disks around young stellar objects is still not entirely understood, which is why spectrally and spatially resolved observations are needed. Recently, the Atacama Large Millimetre/sub-millimetre Array (ALMA) carried out long-baseline observations towards a handful of young sources, revealing connections between outflows and the inner regions of disks. Aims. Here we aim to determine the small-scale kinematical and morphological properties of the outflow from the isolated protostar B335 for which no Keplerian disk has, so far, been observed on scales down to 10 au. Methods. We used ALMA in its longest-baseline configuration to observe emission from CO isotopologues, SiO, SO2, and CH3OH. The proximity of B335 provides a resolution of ~3 au (0.03′′). We also combined our long-baseline data with archival observations to produce a high-fidelity image covering scales up to 700 au (7′′). Results. 12CO has an X-shaped morphology with arms ~50 au in width that we associate with the walls of an outflow cavity, similar to what is observed on larger scales. Long-baseline continuum emission is confined to <7 au from the protostar, while short-baseline continuum emission follows the 12CO outflow and cavity walls. Methanol is detected within ~30 au of the protostar. SiO is also detected in the vicinity of the protostar, but extended along the outflow. Conclusions. The 12CO outflow does not show any clear signs of rotation at distances ≳30 au from the protostar. SiO traces the protostellar jet on small scales, but without obvious rotation. CH3OH and SO2 trace a region <16 au in diameter, centred on the continuum peak, which is clearly rotating. Using episodic, high-velocity, 12CO features, we estimate the launching radius of the outflow to be <0.1 au and dynamical timescales of the order of a few years.

scholarly journals Identification of Class I Methanol Masers with Objects of Near and Mid-Infrared Bands and the Third Version of the Class I Methanol Maser (MMI) Catalog

2012 ◽  
Vol 8 (S287) ◽  
pp. 280-281
Author(s):  
Olga Bayandina ◽  
Irina Val'tts ◽  
Grigorii Larionov
Keyword(s):  
Galactic Plane ◽  
Short Wave ◽  
Class I ◽  
Young Stellar Objects ◽  
Bipolar Outflows ◽  
Stellar Objects ◽  
Mid Infrared ◽  
Dark Clouds ◽  
The Third ◽  
Methanol Masers

AbstractAn identification has been conducted of class I methanol masers with 1) short-wave infrared objects EGO (extended green objects) - tracer bipolar outflow of matter in young stellar objects, and 2) isolated pre-protostellar gas-dust cores of the interstellar medium which are observed in absorption in the mid-infrared in the Galactic plane. It is shown that more than 50% of class I methanol masers are identified with bipolar outflows, considering the EGO as bipolar outflows (as compared with the result of 22% in the first version of the MMI catalog that contains no information about EGO). 99 from 139 class I methanol masers (71%) are identified with SDC. Thus, it seems possible that the MMI can be formed in isolated self-gravitating condensations, which are the silhouette of dark clouds - IRDC and SDC.

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