Stellar populations in the BAaDE survey

2019 ◽  
Vol 14 (S353) ◽  
pp. 43-44
Author(s):  
Megan O. Lewis ◽  
Ylva M. Pihlström ◽  
Loránt O. Sjouwerman ◽  
Michael C. Stroh ◽  
Keyword(s):  
Detection Rate ◽  
Galactic Plane ◽  
Dynamical Evolution ◽  
Stellar Populations ◽  
Young Stellar Objects ◽  
Line Of Sight ◽  
Stellar Objects ◽  
Evolved Stars ◽  
Color Identification ◽  
Infrared Sources

AbstractThe BAaDE (Bulge Asymmetries and Dynamical Evolution) project is an SiO maser survey of the Galactic Plane. About 19,000 sources have been observed at 43 GHz with the VLA, and the production of spectra for each of these sources is well underway. The primary goal of the project is to collect line-of-sight velocities for all the detected masers in the sample to probe Galactic dynamics. With an expected detection rate of over 60% we should collect over 11,000 velocities to probe the Galactic potential. The survey is also a large sample of infrared sources to explore the different evolved stellar populations within the Milky Way. So far we discern three distinct groups in the BAaDE sample: the main group containing oxygen-rich, evolved stars with a high SiO maser detection rate, a much smaller population of carbon-rich evolved stars, and finally a group of likely young stellar objects with no maser emission. These populations are separated using 2MASS and MSX color-color diagrams, and we find a particularly useful cut between the young and evolved objects using the MSX [D] –[E] color. Identification of these populations will isolate BAaDE’s evolved star sample, and will more tightly define the region in IR color-color diagrams where SiO masers occur yielding a better understanding of these kinematical probes. Using our color-divisions we can also study the distribution of each of the populations within the Galactic Plane.

scholarly journals The RMS survey: radio observations of candidate massive YSOs in the southern hemisphere

2006 ◽  
Vol 2 (S237) ◽  
pp. 482-482 ◽  
Author(s):  
J. S. Urquhart ◽  
A. L. Busfield ◽  
M. G. Hoare ◽  
S. L. Lumsden ◽  
A. J. Clarke ◽  
...  
Keyword(s):  
Hii Regions ◽  
Point Sources ◽  
Radio Continuum ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Evolved Stars ◽  
Multi Wavelength ◽  
Sources Of Contamination ◽  
Compact Array

AbstractThe Red MSX Source (RMS) survey (Hoare et al. 2005) is a multi-wavelength programme of follow-up observations designed to distinguish between genuine massive young stellar objects (MYSOs) and other embedded or dusty objects, such as ultra compact (UC) HII regions, evolved stars and planetary nebulae (PNe). We have identified nearly 2000 MYSOs candidates by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. There are several other types of embedded or dust enshrouded objects that have similar colours as MYSOs and contaminate our sample. Two sources of contamination are from UCHII regions and PNe, both of which can be identified from the radio emission emitted by their ionised nebulae. In order to identify UCHII regions and PNe that contaminate our sample we have conducted high resolution radio continuum observations at 3.6 and 6 cm of all southern MYSOs candidates (235° < l < 350°) using the Australia Telescope Compact Array (ATCA).

Laboratory investigations aimed at building a database for the interpretation of JWST spectra

2019 ◽  
Vol 15 (S350) ◽  
pp. 77-80
Author(s):  
Maria Elisabetta Palumbo ◽  
Giuseppe A. Baratta ◽  
Gleb Fedoseev ◽  
Daniele Fulvio ◽  
Carlotta Scirè ◽  
...  
Keyword(s):  
Thermal Processing ◽  
Laboratory Data ◽  
Cosmic Ray ◽  
Peak Position ◽  
Young Stellar Objects ◽  
Line Of Sight ◽  
High Quality ◽  
Stellar Objects ◽  
James Webb Space Telescope ◽  
Laboratory Investigations

AbstractThe James Webb Space Telescope (JWST) is expected to be launched in 2021. The JWST’s science instruments will provide high quality spectra acquired in the line of sight to young stellar objects whose interpretation will require a robust database of laboratory data. With this in mind, an experimental work is in progress in the Laboratory for Experimental Astrophysics in Catania to study the profile (shape, width, and peak position) of the main infrared bands of molecular species expected to be present in icy grain mantles. Our study also takes into account the modifications induced on icy samples by low-energy cosmic ray bombardment and by thermal processing. Here we present some recent results on deuterium hydrogen monoxide (HDO), N-bearing species, and carbon dioxide (CO2).

scholarly journals Dust Evolution in Protoplanetary Disks

1996 ◽  
Vol 150 ◽  
pp. 513-516
Author(s):  
Thomas Henning ◽  
Wolfgang Schmitt ◽  
Hubert Klahr ◽  
Rastislav Mucha
Keyword(s):  
Numerical Study ◽  
Dynamical Evolution ◽  
Dynamical Behaviour ◽  
Young Stellar Objects ◽  
Dust Particles ◽  
Circumstellar Disk ◽  
Stellar Objects ◽  
One Dimensional ◽  
First Results ◽  
Dust Evolution

AbstractThe evolution of dust particles in circumstellar disk-like structures around protostars and young stellar objects is discussed. We especially consider the coagulation of grains due to collisional aggregation and the influence of this process on the optical properties of the particles. These dust opacities are important for both the derivation of the circumstellar dust mass from submillimetre continuum observations and the dynamical behaviour of the disks.We present first results of a numerical study of the coagulation of dust grains in a turbulent protoplanetary accretion disk described by a time-dependent one-dimensional (radial) “alpha” model. The influence of grain opacity changes due to dust coagulation on the dynamical evolution of a protostellar disk is investigated. In addition, we consider the grain motion in two-dimensional disks.

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 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.

scholarly journals G54.4–0.3 — Multi-Frequency Investigation of an SNR in Interaction with the ISM

1996 ◽  
Vol 169 ◽  
pp. 627-628
Author(s):  
N. Junkes
Keyword(s):  
Interstellar Medium ◽  
Northern Hemisphere ◽  
Supernova Remnant ◽  
Galactic Plane ◽  
Point Sources ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Shell Type ◽  
Fir Spectra

G54.4–0.3 is an extended shell-type supernova remnant (SNR) in the Galactic plane. We selected this source as a candidate for the interaction of SNRs with the interstellar medium on the base of an investigation of cool IRAS point sources in the direction of SNRs. We found a statistical excess of IRAS sources with FIR spectra similar to young stellar objects (Td ≈ 25 − 45 K) in the vicinity of G54.4–0.3 and a number of other SNRs in the northern hemisphere (Junkes & Fürst 1992).

BAaDE: The Bulge Asymmetries and Dynamical Evolution survey

2019 ◽  
Vol 14 (S353) ◽  
pp. 45-46
Author(s):  
Loránt O. Sjouwerman ◽  
Ylva M. Pihlström ◽  
Michael C. Stroh ◽  
Megan O. Lewis ◽  
Mark J Claussen ◽  
...  
Keyword(s):  
Dynamical Evolution ◽  
High Rate ◽  
Spectral Energy ◽  
Dynamical Structure ◽  
Energy Distributions ◽  
Evolved Stars ◽  
The Galaxy ◽  
Maser Line ◽  
Infrared Spectral ◽  
Infrared Sources

AbstractThe Bulge Asymmetries and Dynamical Evolution (BAaDE) survey aims to use circumstellar SiO maser line-of-sight velocities as probes for the Galactic gravitational potential and dynamical structure. The SiO masers are detected at a high rate in specific color-selected MSX infrared sources. Furthermore, the SiO maser properties and line ratios, in combination with infrared spectral energy distributions and location in the Galaxy, will statistically yield detailed information on population and evolution of low- to intermediate-mass evolved stars in the Galaxy.

scholarly journals VARIABLE EVOLVED STARS AND YOUNG STELLAR OBJECTS DISCOVERED IN THE LARGE MAGELLANIC CLOUD USING THESAGESURVEY

2009 ◽  
Vol 137 (2) ◽  
pp. 3139-3148 ◽  
Author(s):  
Uma P. Vijh ◽  
M. Meixner ◽  
B. Babler ◽  
M. Block ◽  
S. Bracker ◽  
...  
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Evolved Stars
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