scholarly journals The local spiral structure of the Milky Way

2016 ◽  
Vol 2 (9) ◽  
pp. e1600878 ◽  
Author(s):  
Ye Xu ◽  
Mark Reid ◽  
Thomas Dame ◽  
Karl Menten ◽  
Nobuyuki Sakai ◽  
...  
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Spiral Structure ◽  
Formation Rate ◽  
Great Distance ◽  
High Mass ◽  
Mass Star ◽  
Distance Measurements ◽  
Spiral Arms ◽  
Long Baseline

The nature of the spiral structure of the Milky Way has long been debated. Only in the last decade have astronomers been able to accurately measure distances to a substantial number of high-mass star-forming regions, the classic tracers of spiral structure in galaxies. We report distance measurements at radio wavelengths using the Very Long Baseline Array for eight regions of massive star formation near the Local spiral arm of the Milky Way. Combined with previous measurements, these observations reveal that the Local Arm is larger than previously thought, and both its pitch angle and star formation rate are comparable to those of the Galaxy’s major spiral arms, such as Sagittarius and Perseus. Toward the constellation Cygnus, sources in the Local Arm extend for a great distance along our line of sight and roughly along the solar orbit. Because of this orientation, these sources cluster both on the sky and in velocity to form the complex and long enigmatic Cygnus X region. We also identify a spur that branches between the Local and Sagittarius spiral arms.

Structure of the Milky Way: View from the Southern Hemisphere

2017 ◽  
Vol 13 (S336) ◽  
pp. 154-157
Author(s):  
Lucas J. Hyland ◽  
Simon P. Ellingsen ◽  
Mark J. Reid
Keyword(s):  
Southern Hemisphere ◽  
High Precision ◽  
Large Scale ◽  
Milky Way ◽  
Spiral Structure ◽  
High Mass ◽  
Mass Star ◽  
Spiral Arms ◽  
Long Baseline ◽  
Trigonometric Parallax

AbstractThe exclusive association of Class II methanol masers with high mass star formation regions and in turn spiral arms, makes them ideal tracers of spiral structure. The bright and compact nature of masers also makes them good sources for Very Long Baseline Interferometry, with their fluxes visible on some of the longest terrestrial baselines. The success of the BeSSeL (Bar and Spiral Structure Legacy) project has demonstrated the use of masers in large scale high–precision trigonometric parallax surveys. This survey was then able to precisely map the spiral arms visible from the Northern Hemisphere and recalculate the fundamental Milky Way parameters R0 and θ0. The majority of the Milky Way is visible from the Southern Hemisphere and at the present time the Australian LBA (Long Baseline Array) is the only Southern Hemisphere array capable of taking high–precision trigonometric parallax data. We present the progress–to–date of the Southern Hemisphere experiment. We will also unveil a new broadband Southern Hemisphere array, capable of much faster parallax turnaround and atmospheric calibration.

scholarly journals Molecular Gas Kinematics and High-Mass Star Formation in the Spiral Arms of the Milky Way

2004 ◽  
Vol 191 ◽  
pp. 143-144
Author(s):  
A. Luna ◽  
L. Carrasco ◽  
L. Ortega ◽  
L. Bronfman ◽  
O. Yam
Keyword(s):  
Star Formation ◽  
Rigid Body ◽  
Large Scale ◽  
Milky Way ◽  
Stellar System ◽  
High Mass ◽  
Rotational Line ◽  
Molecular Gas ◽  
Mass Star ◽  
Spiral Arms

AbstractWe study the kinematic of the molecular gas using observations of the rotational line 12CO(J=1→0), and also the star formation traced by Ultra-Compact HII regions in the IV galactic quadrant (270° ≤ l ≤ 360°). Our results show that there is a connection between 1) high-mass star formation in the spiral arms of the Milky Way, 2) molecular gas of high column density, and 3) the large-scale rigid-body-like motion of the gas. The large-scale rigid-body-like motions observed in the arms imply that there is less angular momentum to dissipate in the formation processes of stellar systems. We show a multiple stellar system under study, embedded in its parent molecular cloud in the Carina arm region.

scholarly journals Combination of CN(1-0), HCN(1-0), and HNC(1-0): A possible indicator for a high-mass star formation sequence in the Milky Way

2015 ◽  
Vol 576 ◽  
pp. A131 ◽  
Author(s):  
X. H. Han ◽  
J. J. Zhou ◽  
J. Z. Wang ◽  
J. Esimbek ◽  
J. S. Zhang ◽  
...  
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
High Mass ◽  
Mass Star

scholarly journals The JCMT Legacy Survey: Mapping the Milky Way in the Submillimetre

2009 ◽  
Vol 5 (H15) ◽  
pp. 797-797
Author(s):  
Antonio Chrysostomou ◽  
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
High Mass ◽  
Mass Star ◽  
Valuable Resource ◽  
Spectral Window ◽  
Multi Wavelength ◽  
Second Year ◽  
Near Future

AbstractThe JCMT Legacy Survey (JLS) is an ambitious programme of independent surveys to study our Galaxy and universe in the submillimetre (λ = 450 − 850 μm) from the summit of Mauna Kea, Hawaii. With its scientific breadth and unique spectral window, it is clear that the JLS will have a significant impact on star formation studies in the near future and beyond. Its complementarity with other surveys (e.g. Spitzer, Herschel) will make the JLS a very valuable resource for multi-wavelength studies for low and high-mass star formation across the Milky Way. The JLS is currently in its second year of operation.

scholarly journals High-Mass Star and Massive Cluster Formation in the Milky Way

2018 ◽  
Vol 56 (1) ◽  
pp. 41-82 ◽  
Author(s):  
Frédérique Motte ◽  
Sylvain Bontemps ◽  
Fabien Louvet
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Galactic Plane ◽  
Cluster Formation ◽  
Theoretical Models ◽  
High Mass ◽  
High Angular Resolution ◽  
Mass Star ◽  
Star Forming ◽  
Massive Cluster

This review examines the state-of-the-art knowledge of high-mass star and massive cluster formation, gained from ambitious observational surveys, which acknowledges the multiscale characteristics of these processes. After a brief overview of theoretical models and main open issues, we present observational searches for the evolutionary phases of high-mass star formation, first among high-luminosity sources and more recently among young massive protostars and the elusive high-mass prestellar cores. We then introduce the most likely evolutionary scenario for high-mass star formation, which emphasizes the link of high-mass star formation to massive cloud and cluster formation. Finally, we introduce the first attempts to search for variations of the star-formation activity and cluster formation in molecular cloud complexes in the most extreme star-forming sites and across the Milky Way. The combination of Galactic plane surveys and high–angular resolution images with submillimeter facilities such as Atacama Large Millimeter Array (ALMA) are prerequisites to make significant progress in the forthcoming decade.

scholarly journals The Spiral Structure in the Solar Neighborhood

2021 ◽  
Vol 8 ◽  
Author(s):  
L. G. Hou
Keyword(s):  
Spiral Structure ◽  
Open Clusters ◽  
Solar Neighborhood ◽  
High Mass ◽  
Mass Star ◽  
Giant Molecular Clouds ◽  
Star Formation Region ◽  
Spiral Arms ◽  
Different Types ◽  
Better Than

The spiral structure in the solar neighborhood is an important issue in astronomy. In the past few years, there has been significant progress in observation. The distances for a large number of good spiral tracers, i.e., giant molecular clouds, high-mass star-formation region masers, HII regions, O-type stars, and young open clusters, have been accurately estimated, making it possible to depict the detailed properties of nearby spiral arms. In this work, we first give an overview about the research status for the Galaxy’s spiral structure based on different types of tracers. Then the objects with distance uncertainties better than 15% and <0.5 kpc are collected and combined together to depict the spiral structure in the solar neighborhood. Five segments related with the Perseus, Local, Sagittarius-Carina, Scutum-Centaurus, and Norma arms are traced. With the large dataset, the parameters of the nearby arm segments are fitted and updated. Besides the dominant spiral arms, some substructures probably related to arm spurs or feathers are also noticed and discussed.

A CCD Hα Survey of Nearby Southern Spiral Galaxies

1991 ◽  
Vol 9 (1) ◽  
pp. 89-90
Author(s):  
Stuart D. Ryder ◽  
Michael A. Dopita
Keyword(s):  
Star Formation ◽  
Observational Data ◽  
Spiral Galaxies ◽  
Star Formation Rate ◽  
Formation Rate ◽  
High Mass ◽  
H Ii Regions ◽  
Mass Star ◽  
Reliable Measure ◽  
Initial Results

AbstractSome initial results of a flux-calibrated CCD Hα imaging program of bright, nearby southern spiral galaxies are presented. Very few southern hemisphere spiral galaxies have ever been completely imaged in Hα, let alone with a CCD. This survey (which mainly uses the MSSSO 1.0-m reflector with an f/3.5 focal reducer) will, when combined with spectrophotometry of the H II regions thus revealed, allow us to trace the chemical evolution of each galaxy. Furthermore, since the absolute Hα flux is a reliable measure of the high-mass star formation rate in a galaxy, such observational data will permit us to test the predictions of the various star formation theories.

scholarly journals High-mass stars in Milky Way clusters

2016 ◽  
Vol 12 (S329) ◽  
pp. 271-278
Author(s):  
Ignacio Negueruela
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Theoretical Models ◽  
Open Clusters ◽  
High Mass ◽  
Mass Star ◽  
Formation And Evolution

AbstractYoung open clusters are our laboratories for studying high-mass star formation and evolution. Unfortunately, the information that they provide is difficult to interpret, and sometimes contradictory. In this contribution, I present a few examples of the uncertainties that we face when confronting observations with theoretical models and our own assumptions.

scholarly journals Comparing galaxy formation in the L-GALAXIES semi-analytical model and the IllustrisTNG simulations

2021 ◽  
Vol 502 (1) ◽  
pp. 1051-1069
Author(s):  
Mohammadreza Ayromlou ◽  
Dylan Nelson ◽  
Robert M Yates ◽  
Guinevere Kauffmann ◽  
Malin Renneby ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Analytical Model ◽  
Formation Rate ◽  
Stellar Mass ◽  
Gas Content ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Hydrodynamical Simulations

ABSTRACT We perform a comparison, object by object and statistically, between the Munich semi-analytical model, L-GALAXIES, and the IllustrisTNG hydrodynamical simulations. By running L-GALAXIES on the IllustrisTNG dark matter-only merger trees, we identify the same galaxies in the two models. This allows us to compare the stellar mass, star formation rate, and gas content of galaxies, as well as the baryonic content of subhaloes and haloes in the two models. We find that both the stellar mass functions and the stellar masses of individual galaxies agree to better than ${\sim} 0.2\,$dex. On the other hand, specific star formation rates and gas contents can differ more substantially. At z = 0, the transition between low-mass star-forming galaxies and high-mass quenched galaxies occurs at a stellar mass scale ${\sim} 0.5\,$dex lower in IllustrisTNG than that in L-GALAXIES. IllustrisTNG also produces substantially more quenched galaxies at higher redshifts. Both models predict a halo baryon fraction close to the cosmic value for clusters, but IllustrisTNG predicts lower baryon fractions in group environments. These differences are primarily due to differences in modelling feedback from stars and supermassive black holes. The gas content and star formation rates of galaxies in and around clusters and groups differ substantially, with IllustrisTNG satellites less star forming and less gas rich. We show that environmental processes such as ram-pressure stripping are stronger and operate to larger distances and for a broader host mass range in IllustrisTNG. We suggest that the treatment of galaxy evolution in the semi-analytic model needs to be improved by prescriptions that capture local environmental effects more accurately.

scholarly journals The young stellar population of the metal-poor galaxy NGC 6822

2019 ◽  
Vol 490 (1) ◽  
pp. 832-847 ◽  
Author(s):  
Olivia C Jones ◽  
Michael J Sharp ◽  
Megan Reiter ◽  
Alec S Hirschauer ◽  
M Meixner ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Initial Mass Function ◽  
High Mass ◽  
Spectral Energy ◽  
Mass Star ◽  
Star Formation Regions ◽  
Ngc 6822

ABSTRACT We present a comprehensive study of massive young stellar objects (YSOs) in the metal-poor galaxy NGC 6822 using IRAC and MIPS data obtained from the Spitzer Space Telescope. We find over 500 new YSO candidates in seven massive star formation regions; these sources were selected using six colour–magnitude cuts. Via spectral energy distribution fitting to the data with YSO radiative transfer models we refine this list, identifying 105 high-confidence and 88 medium-confidence YSO candidates. For these sources, we constrain their evolutionary state and estimate their physical properties. The majority of our YSO candidates are massive protostars with an accreting envelope in the initial stages of formation. We fit the mass distribution of the Stage I YSOs with a Kroupa initial mass function and determine a global star formation rate of 0.039 $\mathrm{M}_{\odot } \, \mathrm{yr}^{-1}$. This is higher than star formation rate estimates based on integrated UV fluxes. The new YSO candidates are preferentially located in clusters which correspond to seven active high-mass star-formation regions which are strongly correlated with the 8 and 24 μm emission from PAHs and warm dust. This analysis reveals an embedded high-mass star formation region, Spitzer I, which hosts the highest number of massive YSO candidates in NGC 6822. The properties of Spitzer I suggest it is younger and more active than the other prominent H ii and star-formation regions in the galaxy.

Sign in / Sign up

Export Citation Format

Share Document