The observed spiral structure of the Milky Way

Abstract

The spiral structure of the Milky Way is not yet well determined. The keys to understanding this structure are to increase the number of reliable spiral tracers and to determine their distances as accurately as possible. HII regions, giant molecular clouds (GMCs), and 6.7-GHz methanol masers are closely related to high mass star formation, and hence they are excellent spiral tracers. We update the catalogs of Galactic HII regions, GMCs, and 6.7-GHz methanol masers, and then outline the spiral structure of the Milky Way. We collected data for more than 2500 known HII regions, 1300 GMCs, and 900 6.7-GHz methanol masers. If the photometric or trigonometric distance was not yet available, we determined the kinematic distance using a Galaxy rotation curve with the current IAU standard, $R_0$ = 8.5 kpc and ${\Theta }_0$ = 220 km s${}^{-1}$, and the most recent updated values of $R_0$ = 8.3 kpc and ${\Theta }_0$ = 239 km s${}^{-1}$, after we modified the velocities of tracers with the adopted solar motions. With the weight factors based on the excitation parameters of HII regions or the masses of GMCs, we get the distributions of these spiral tracers. The distribution of tracers shows at least four segments of arms in the first Galactic quadrant, and three segments in the fourth quadrant. The Perseus Arm and the Local Arm are also delineated by many bright HII regions. The arm segments traced by massive star forming regions and GMCs are able to match the HI arms in the outer Galaxy. We found that the models of three-arm and four-arm logarithmic spirals are able to connect most spiral tracers. A model of polynomial-logarithmic spirals is also proposed, which not only delineates the tracer distribution, but also matches the observed tangential directions.

22 Pages, 16 Figures, 7 Tables, updated to match the published version

References in corpus (28)

• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• A Class I and Class II Methanol Maser Survey of Extended Green Objects (EGOs) from the GLIMPSE Survey
• Kinematic Distances to Molecular Clouds identified in the Galactic Ring Survey
• The Molonglo Galactic Plane Survey (MGPS-2): Compact Source Catalogue
• The Vertical Structure of the Outer Milky Way HI Disk
• The old nuclear star cluster in the Milky Way: dynamics, mass, statistical parallax, and black hole mass
• Resolution of the Distance Ambiguity for Galactic HII Regions
• The 6-GHz Multibeam Maser Survey I. Techniques
• Trigonometric parallaxes of star forming regions in the Sagittarius spiral arm
• 3D Distribution of Molecular Gas in the Barred Milky Way
• Trigonometric Parallaxes of Massive Star Forming Regions: V. G23.01-0.41 and G23.44-0.18
• Spiral structure in the outer Galactic disk. I. The Third Galactic Quadrant
• Radio Recombination Lines in Galactic HII Regions
• Molecular clouds and clumps in the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• The Arecibo Methanol Maser Galactic Plane Survey--I: Data
• Trigonometric Parallaxes of Star Forming Regions in the Scutum Spiral Arm
• The Distances of SNR W41 and overlapping HII regions
• The Distances of SNRs Kes 69 and G21.5-0.9 from HI and 13CO Spectra
• Calculation of the Local Standard of Rest from 20,574 Local Stars in the New Hipparcos Reduction with Known Radial Velocities
• A GLIMPSE-based search for 6.7-GHz Methanol Masers and the lifetime of their spectral features
• Resolving distance ambiguities towards 6.7 GHz methanol masers
• The nature of the methanol maser ring G23.657-00.127
• Two-dimensional metallicity distribution of the ionized gas in NGC 628 and NGC 6946
• Parameters of the Local Warp of the Stellar-Gaseous Galactic Disk from the Kinematics of Tycho-2 Nearby Red Giant Clump Stars
• Probing embedded star clusters in the HII complex NGC 6357 with VVV
• A study of the neglected Galactic HII region NGC 2579 and its companion ESO 370-9
• On the central ionizing star of G23.96+0.15 and near-IR spectral classification of O stars

Cited by in corpus (112)

• A New Electron Density Model for Estimation of Pulsar and FRB Distances
• Painting a portrait of the Galactic disc with its stellar clusters
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• Rings and Radial Waves in the Disk of the Milky Way
• The FAST Galactic Plane Pulsar Snapshot survey: I. Project design and pulsar discoveries
• Pulsar Rotation Measures and Large-scale Magnetic Field Reversals in the Galactic Disk
• The gas-to-extinction ratio and the gas distribution in the Galaxy
• The spiral pattern rotation speed of the Galaxy and the corotation radius with GAIA DR2
• The Coherent Magnetic Field of the Milky Way
• A Census of Large-Scale ($\ge$ 10 pc), Velocity-Coherent, Dense Filaments in the Northern Galactic Plane: Automated Identification Using Minimum Spanning Tree
• A comparison of Galactic electron density models using PyGEDM
• Gas Dynamics in the Galaxy: Total Mass Distribution and the Bar Pattern Speed
• Parallaxes of Star Forming Regions in the Outer Spiral Arm of the Milky Way
• Evolution of the local spiral structure of the Milky Way revealed by open clusters
• Proper motions and kinematics of selected bulge globular clusters
• Mapping Luminous Hot Stars in the Galaxy
• Local spiral structure based on the Gaia EDR3 parallaxes
• A stripped helium star in the potential black hole binary LB-1
• A guided map to the Spiral arms in the galactic disk of the Milky Way
• The Galactic spiral structure as revealed by O- and early B-type stars
• A radio-polarisation and rotation measure study of the Gum Nebula and its environment
• The Bar and Spiral Arms in the Milky Way: Structure and Kinematics
• What Does the Milky Way Look Like?
• Chemo-kinematics of the Milky Way spiral arms and bar resonances: connection to ridges and moving groups in the Solar vicinity
• Tracing the Galactic spiral structure with embedded clusters
• Tracing the Spiral Structure of the Outer Milky Way with Dense Atomic Hydrogen Gas
• The prevalence of star formation as a function of Galactocentric radius
• The FAST Galactic Plane Pulsar Snapshot survey: VI. The discovery of 473 new pulsars
• Tracing the Milky Way warp and spiral arms with classical Cepheids
• Milky Way Tomography with K and M Dwarf Stars: the Vertical Structure of the Galactic Disk
• Gaia-DR2 extended kinematical maps. Part II: Dynamics in the Galactic disk explaining radial and vertical velocities
• The low-mass population in the young cluster Stock 8: Stellar properties and Initial Mass Function
• The spiral structure in the Solar neighborhood
• The Forgotten Quadrant Survey. ${}^{12}$CO and ${}^{13}$CO (1-0) survey of the Galactic Plane in the range 220°$<l<$240° -2.5°$<b<$0°
• Constraining the pitch angle of the Galactic spiral arms in the Milky Way
• The dynamical origin of the Local arm and the Sun's trapped orbit
• Exploring the origin of moving groups and diagonal ridges by simulations of stellar orbits and birthplaces
• Star formation around mid-infrared bubble N37: Evidence of cloud-cloud collision
• Local stellar formation history from the 40 pc white dwarf sample
• FEDReD II : 3D Extinction Map with 2MASS and Gaia DR2 data
• Gaia-DR2 distance to the W3 Complex in the Perseus Arm
• Analysis of galaxy kinematics based on Cepheids from the Gaia DR2 Catalogue
• The SEDIGISM survey: The influence of spiral arms on the molecular gas distribution of the inner Milky Way
• Modelling resonances and orbital chaos in disk galaxies. Application to a Milky Way spiral model
• Young stars as tracers of a barred-spiral Milky Way
• CRIRES high-resolution near-infrared spectroscopy of diffuse interstellar band profiles. Detection of 12 new DIBs in the YJ band and the introduction of a combined ISM sight line and stellar analysis approach
• The power of co-ordinate transformations in dynamical interpretations of Galactic structure
• The new magnetar SGR J1830-0645 in outburst
• Molecular cloud catalogue from ${}^{13}$CO(1-0) data of the Forgotten Quadrant Survey
• The Great Wave: Evidence of a large-scale vertical corrugation propagating outwards in the Galactic disc
• The Gould Belt, the de Vaucouleurs-Dolidze Belt, and the Orion Arm
• Kinematic footprint of the Milky Way spiral arms in Gaia EDR3
• The Galactic neutron star population I - an extragalactic view of the Milky Way and the implications for fast radio bursts
• 2D chemical evolution models II. Effects of multiple spiral arm patterns on O, Eu, Fe and Ba abundance gradients
• Peering into the Milky Way by FAST: II. Ionized gas in the inner Galactic disk revealed by the piggyback line observations of the FAST GPPS survey
• The Norma spiral arm: large-scale pitch angle
• Estimating the local dark matter density in a non-axisymmetric wobbling disc
• A comprehensive photometric study of dynamically evolved small van den Bergh-Hagen open clusters
• A Map of the Local Velocity Substructure in the Milky Way Disk
• Towards a comprehensive knowledge of the open cluster Haffner 9
• Blue extreme disk-runaway stars with Gaia EDR3
• Star forming activity in the H II regions associated with IRAS 17160-3707 complex
• Modeling of Spiral Structure in a Multi-Component Milky~Way-Like Galaxy
• Bayesian inference of three-dimensional gas maps: I. Galactic CO
• Stellar encounters with giant molecular clouds
• Vertical Structure and Kinematics of the Galactic Outer Disk
• A Sino-German 6cm polarisation survey of the Galactic plane IX. HII regions
• Synthetic observations of spiral arm tracers of a simulated Milky Way analog
• Ionization age of iron ejecta in the Galactic Type Ia supernova remnant G306.3-0.9
• Growing Local arm inferred by the breathing motion
• Peering into the Milky Way by FAST: III. Magnetic fields in the Galactic halo and farther spiral arms revealed by the Faraday effect of faint pulsars
• Constraining HeII Reionization Detection Uncertainties via Fast Radio Bursts
• Tilted outer and inner structures in edge-on galaxies?
• The Galactic HII Region Luminosity Function at Radio and Infrared Wavelengths
• Star formation activity beyond the outer Arm I: WISE-selected candidate star-forming regions
• Parallax-based Distances to Galactic Hii Regions: Nearby Spiral Structure
• Contribution of young massive star clusters to Galactic diffuse $\gamma$-ray emission
• Discovery of a new supernova remnant G21.8-3.0
• FEDReD III : Unraveling the 3D structure of Vela
• Galactic Kinematics from Data on Open Star Clusters from the MWSC Catalogue
• Probing the physical conditions and star formation processes in the Galactic HII region S305
• The Outer spiral arm of the Milky Way using Red Clump stars
• NE2025: An Updated Electron Density Model for the Galactic Interstellar Medium
• Radio Recombination Line Observations at $1.0-1.5$ GHz with FAST
• A Low Frequency Pilot Survey of Southern HII Regions in the Vela Constellation
• Surveying the Giant HII Regions of the Milky Way with SOFIA: IV. Sgr D, W42, and a Reassessment of the Giant HII Region Census
• Galactic HI supershells: Kinetic energies and possible origin
• Oumuamuas passing through molecular clouds
• The nearby Galaxy structure toward the Vela Gum nebula
• Interarm islands in the Milky Way -- the one near the Cygnus spiral arm
• Multi-band observations of Swift J0840.7-3516: a new transient ultra-compact X-ray binary candidate
• A new method of reconstructing Galactic three-dimensional structures using ultralong-wavelength radio observations
• Redetermination of the Parameters of the Galactic Spiral Pattern from Classical Cepheids
• On the physical reality of overlooked open clusters
• Estimation of the Parameters of the Spiral Pattern in the Galaxy Based on a Sample of Classical Cepheids
• A revised view of the Canis Major stellar overdensity with DECam and Gaia: new evidence of a stellar warp of blue stars
• Local dark matter density from Gaia DR3 K-dwarfs using Gaussian processes
• Damping of the Milky Way bar by manifold-driven spirals
• Star Formation Law in the Milky Way
• Gaia20bdk -- a new FUor in Sh 2-301 Star Forming Region
• Study of pulsar flux density and its variability with Parkes data archive
• Distances of Galactic Radio Pulsars; First Quadrant: $-2^{\circ }<\ell <90^{\circ }$ and $-2^{\circ }<b<2^{\circ }$
• Evidence for protostellar jets as a population of hadronic gamma-ray sources
• Investigating the vertical distribution of the disk as a function of radial action: Results from simulations
• Mapping the reddening plane in the Galactic disk through interstellar extinction of open clusters
• The Spiral Pattern Speed in the Milky Way Galaxy
• The SARAO MeerKAT Galactic Plane Survey filamentary source catalogue
• Discovery of a runaway star likely ejected by a Type Iax Supernova
• Tidal tails in open clusters: Morphology, binary fraction, dynamics, and rotation
• MIRIS Paα Galactic Plane Survey. II. The Catalog of Paα Emission-line Sources
• Distance and extinction to the Milky Way spiral arms along the Galactic centre line of sight
• The GPSP Atlas: High-resolution Galactic Photon Survival Probability Atlas for Very-High- and Ultra-High-Energy Gamma-Ray Astronomy