The Origin of Large Peculiar Motions of Star-Forming Regions and Spiral Structures of Our Galaxy

Baba, Junichi; Asaki, Y.; Makino, Junichiro; Miyoshi, Makoto; Saitoh, Takayuki R.; Wada, Keiichi

doi:10.1088/0004-637x/706/1/471

Cited by 93 publications

(107 citation statements)

References 65 publications

(78 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, Baba et al (2009) show from simulations that there is no clear tendency that star-forming gas moves slower than the galactic rotation, and they found the peculiar velocities to be randomly oriented.…”

Section: Distance Calculationmentioning

confidence: 97%

Giving physical significance to the Hi-GAL data: determining the distance of cold dusty cores in the Milky Way

Russeil

Pestalozzi

Mottram

et al. 2011

A&A

View full text Add to dashboard Cite

Context. Hi-GAL, an open time key-project of the Herschel satellite, was awarded 343 hours observing time to carry out a 5-band photometric imaging survey at 70, 160, 250, 350, and 500 μm of a |b| ≤ 1 • wide strip of the Milky Way Galactic plane in the longitude range −70 • ≤ l ≤ 70 • . Two 2 • × 2 • fields centred at l = 30 • and l = 59 • have been observed with the SPIRE and PACS photometric cameras in parallel mode during the Herschel science demonstration phase (SDP). From the images, compact sources are extracted for which the distance must be established in order to determine their physical properties. Aims. The aim of this paper is to present the distance determination strategy for the Hi-GAL compact sources. We illustrate this strategy for the two fields at l = 30 • and l = 59 • . Methods. The first step to determine the distance is to establish the LSR (local standard of rest) velocity of each compact source. The kinematic distance is then determined assuming a rotation curve for our Galaxy. To resolve the distance ambiguity for sources within the solar circle, we adopt a multiwavelength approach combining extinction maps, optical, and near infrared images, and velocity information from NH 3 , CO and HI data. When sources can be kinematically linked to optical H ii regions, the stellar distance of the exciting stars, when known, can be attributed to all linked sources. Results. In the two 2 • × 2 • SDP fields, 2678 compact sources have been identified and listed in the band-merged catalogue. About 93% of these sources have been assigned a radial velocity and distance. Conclusions. A multiwavelength approach is necessary to assign the correct velocity to sources (especially when CO spectra have a lot of features) and to determine the distance by solving the distance ambiguity. Also, several Hi-GAL sources seem to be in the interarm region. These sources have to be investigated with dedicated programme to be compared with sources located in the spiral arms.

show abstract

Section: Distance Calculationmentioning

confidence: 97%

Giving physical significance to the Hi-GAL data: determining the distance of cold dusty cores in the Milky Way

Russeil

Pestalozzi

Mottram

et al. 2011

A&A

View full text Add to dashboard Cite

show abstract

“…The Galaxy is decomposed into halo, disc and bulge components, the density profiles for which are used to set the initial positions of the star particles by the tabulation and sampling of mass distribution functions. We initialise the velocities using the procedures from Hernquist (1993), also used by Baba et al (2009), which primarily requires integrating the separate moments of the collisonless Boltzmann equation. Velocities of the disc are circular with some dispersion, while the velocities of the halo and bulge are set in random orientations.…”

Section: Initial Conditions and Galactic Potentialsmentioning

confidence: 99%

The morphology of the Milky Way – II. Reconstructing CO maps from disc galaxies with live stellar distributions

Pettitt¹,

Dobbs²,

Acreman³

et al. 2015

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

The arm structure of the Milky Way remains somewhat of an unknown, with observational studies hindered by our location within the Galactic disc. In the work presented here we use smoothed particle hydrodynamics (SPH) and radiative transfer to create synthetic longitude-velocity observations. Our aim is to reverse-engineer a top down map of the Galaxy by comparing synthetic longitude-velocity maps to those observed. We set up a system of N -body particles to represent the disc and bulge, allowing for dynamic creation of spiral features. Interstellar gas, and the molecular content, is evolved alongside the stellar system. A 3D-radiative transfer code is then used to compare the models to observational data. The resulting models display arm features that are a good reproduction of many of the observed emission structures of the Milky Way. These arms however are dynamic and transient, allowing for a wide range of morphologies not possible with standard density wave theory. The best fitting models are a much better match than previous work using fixed potentials. They favour a 4-armed model with a pitch angle of approximately 20• , though with a pattern speed that decreases with increasing Galactic radius. Inner bars are lacking however, which appear required to fully reproduce the central molecular zone.

show abstract

“…In addition, their recommended fit assumes that the massive star-forming gas orbits slower the Galaxy than expected for circular rotation, which has been questioned by some subsequent studies (Baba et al 2009;McMillan & Binney 2010).…”

Section: B42 Rotation Curvementioning

confidence: 99%

Stellar clusters in the inner Galaxy and their correlation with cold dust emission

Morales

Wyrowski

Schüller

et al. 2013

A&A

View full text Add to dashboard Cite

Context. Stars are born within dense clumps of giant molecular clouds, and constitute young stellar agglomerates known as embedded clusters, which only evolve into bound open clusters under special conditions. Aims. We statistically study all embedded clusters (ECs) and open clusters (OCs) known so far in the inner Galaxy, in particular investigating their interaction with the surrounding molecular environment and the differences in their evolution. Methods. We first compiled a merged list of 3904 clusters from optical and infrared cluster catalogs in the literature, including 75 new (mostly embedded) clusters discovered by us in the GLIMPSE survey. From this list, 695 clusters are within the Galactic range | | ≤ 60 • and |b| ≤ 1.5 • covered by the ATLASGAL survey, which was used to search for correlations with submm dust continuum emission tracing dense molecular gas. We defined an evolutionary sequence of five morphological types: deeply embedded cluster (EC1), partially embedded cluster (EC2), emerging open cluster (OC0), OC still associated with a submm clump in the vicinity (OC1), and OC without correlation with ATLASGAL emission (OC2). Together with this process, we performed a thorough literature survey of these 695 clusters, compiling a considerable number of physical and observational properties in a catalog that is publicly available. Results. We found that an OC defined observationally as OC0, OC1, or OC2 and confirmed as a real cluster is equivalent to the physical concept of OC (a bound exposed cluster) for ages in excess of ∼16 Myr. Some observed OCs younger than this limit can actually be unbound associations. We found that our OC and EC samples are roughly complete up to ∼1 kpc and ∼1.8 kpc from the Sun, respectively, beyond which the completeness decays exponentially. Using available age estimates for a few ECs, we derived an upper limit of 3 Myr for the duration of the embedded phase. Combined with the OC age distribution within 3 kpc of the Sun, which shows an excess of young exposed clusters compared to a theoretical fit that considers classical disruption mechanisms, we computed an embedded and young cluster dissolution fraction of 88 ± 8%. This high fraction is thought to be produced by several factors and not only by the classical paradigm of fast gas expulsion.

show abstract

The Origin of Large Peculiar Motions of Star-Forming Regions and Spiral Structures of Our Galaxy

Cited by 93 publications

References 65 publications

Giving physical significance to the Hi-GAL data: determining the distance of cold dusty cores in the Milky Way

Giving physical significance to the Hi-GAL data: determining the distance of cold dusty cores in the Milky Way

The morphology of the Milky Way – II. Reconstructing CO maps from disc galaxies with live stellar distributions

Stellar clusters in the inner Galaxy and their correlation with cold dust emission

Contact Info

Product

Resources

About