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 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 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 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.

First Near-infrared Imaging Polarimetry of Young Stellar Objects in the Circinus Molecular Cloud

2018 ◽  
Vol 234 (2) ◽  
pp. 42 ◽  
Author(s):  
Jungmi Kwon ◽  
Takao Nakagawa ◽  
Motohide Tamura ◽  
James H. Hough ◽  
Minho Choi ◽  
...  
Keyword(s):  
Molecular Cloud ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Young Stellar Objects ◽  
Near Infrared Imaging ◽  
Stellar Objects ◽  
Imaging Polarimetry

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 Bipolar H II regions

2018 ◽  
Vol 617 ◽  
pp. A67 ◽  
Author(s):  
M. R. Samal ◽  
L. Deharveng ◽  
A. Zavagno ◽  
L. D. Anderson ◽  
S. Molinari ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Galactic Plane ◽  
Three Dimensional ◽  
Young Stellar Objects ◽  
Formation Processes ◽  
Two Dimensional ◽  
Stellar Objects ◽  
Flat Structures ◽  
Exciting Star

Aims. We aim to identify bipolar Galactic H II regions and to understand their parental cloud structures, morphologies, evolution, and impact on the formation of new generations of stars. Methods. We use the Spitzer-GLIMPSE, Spitzer-MIPSGAL, and Herschel-Hi-GAL surveys to identify bipolar H II regions and to examine their morphologies. We search for their exciting star(s) using NIR data from the 2MASS, UKIDSS, and VISTA surveys. Massive molecular clumps are detected near these bipolar nebulae, and we estimate their temperatures, column densities, masses, and densities. We locate Class 0/I young stellar objects (YSOs) in their vicinities using the Spitzer and Herschel-PACS emission. Results. Numerical simulations suggest bipolar H II regions form and evolve in a two-dimensional flat- or sheet-like molecular cloud. We identified 16 bipolar nebulae in a zone of the Galactic plane between ℓ ± 60° and |b| < 1°. This small number, when compared with the 1377 bubble H II regions in the same area, suggests that most H II regions form and evolve in a three-dimensional medium. We present the catalogue of the 16 bipolar nebulae and a detailed investigation for six of these. Our results suggest that these regions formed in dense and flat structures that contain filaments. We find that bipolar H II regions have massive clumps in their surroundings. The most compact and massive clumps are always located at the waist of the bipolar nebula, adjacent to the ionised gas. These massive clumps are dense, with a mean density in the range of 105 cm−3 to several 106 cm−3 in their centres. Luminous Class 0/I sources of several thousand solar luminosities, many of which have associated maser emission, are embedded inside these clumps. We suggest that most, if not all, massive 0/I YSO formation has probably been triggered by the expansion of the central bipolar nebula, but the processes involved are still unknown. Modelling of such nebula is needed to understand the star formation processes at play.

scholarly journals Rapid clump formation in discs of young stellar objects class O-I

2014 ◽  
Vol 9 (S310) ◽  
pp. 223-224
Author(s):  
Olga P. Stoyanovskaya ◽  
Valeriy N. Snytnikov
Keyword(s):  
Gravitational Collapse ◽  
Molecular Cloud ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Simultaneous Formation ◽  
Instability Development

AbstractThe formation of planetesimals and large bodies in circumstellar discs can be referred to the stage of massive unstable disc emerging due to the gravitational collapse in the molecular cloud. We have simulated the dynamics of gas and boulder clumps in such systems. The features of instability development in massive disc is discussed. Unlike medium-massive discs the massive disc can provide conditions for simultaneous formation of several clumps as a result of overdensity ring fragmentation. We found regimes where 3, 2 or 1 overdensity ring appear in the disc and then fragment into clumps collecting about a half of the disc mass.

scholarly journals SK 1: A possible case of triggered star formation in perseus

2006 ◽  
Vol 2 (S237) ◽  
pp. 217-221
Author(s):  
Miriam Rengel ◽  
Klaus Hodapp ◽  
Jochen Eislöffel
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Thermal Emission ◽  
Young Stellar Objects ◽  
Wide Field ◽  
Dust Shell ◽  
Stellar Objects ◽  
Star Forming ◽  
Star Forming Regions ◽  
Suitable Target

AbstractAccording to a triggered star formation scenario (e.g. Martin-Pintado & Cernicharo 1987) outflows powered by young stellar objects shape the molecular clouds, can dig cavities, and trigger new star formation. NGC 1333 is an active site of low- and intermediate star formation in Perseus and is a suggested site of self-regulated star formation (Norman & Silk 1980). Therefore it is a suitable target for a study of triggered star formation (e.g. Sandell & Knee 2001, SK1). On the other hand, continuum sub-mm observations of star forming regions can detect dust thermal emission of embedded sources (which drive outflows), and further detailed structures.Within the framework of our wide-field mapping of star formation regions in the Perseus and Orion molecular clouds using SCUBA at 850 and 450 μm, we mapped NCG 1333 with an area of around 14′× 21′. The maps show more structure than the previous maps of the region observed in sub-mm. We have unveiled the known embedded SK 1 source (in the dust shell of the SSV 13 ridge) and detailed structure of the region, among some other young protostars.In agreement with the SK 1 observations, our map of the region shows lumpy filaments and shells/cavities that seem to be created by outflows. The measured mass of SK 1 (~0.07 M) is much less than its virial mass (~0.2-1 M). Our observations support the idea of SK 1 as an event triggered by outflow-driven shells in NGC 1333 (induced by an increase in gas pressure and density due to radiation pressure from the stellar winds that have presumably created the dust shell). This kind of evidences provides a more thorough understanding of the star formation regulation processes.

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