The Bar and Spiral Structure Legacy (BeSSeL) survey: Mapping the Milky Way with VLBI astrometry

Brunthaler, A.; Reid, M. J.; Menten, K. M.; Zheng, Xingwu; Bartkiewicz, A.; Choi, Yoon Kyung; Dame, T. M.; Hachisuka, Kazuya; Immer, K.; Moellenbrock, G.; Moscadelli, L.; Rygl, K. L. J.; Sanna, A.; Sato, M.; Wu, Yunkun; Xu, Ye; Zhang, B.

doi:10.1002/asna.201111560

Cited by 183 publications

(196 citation statements)

References 65 publications

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“…The ratio of Θ 0 /R 0 has been well constrained to be 29.4 ± 0.9 km s −1 kpc −1 . Brunthaler et al (2011) suggested a value of Θ 0 = 239 ± 7 km s −1 . Schönrich (2012) obtained R 0 = 8.27 ± 0.29 kpc and Θ 0 = 238 ± 9 km s −1 by analyzing the stellar kinematics.…”

Section: Fundamental Parameter R 0 θ 0 and Solar Motionsmentioning

confidence: 99%

“…Based on the stellar kinematics in the solar neighborhood, Schönrich et al (2010) revised the solar motions with respect to the Local Standard of Rest (LSR) as U = 11.10 km s −1 (radially inward), V = 12.24 km s −1 (in the direction of Galactic rotation), and W = 7.25 km s −1 (vertically upward, all in J2000), which are inherently incorporated in the LSR velocities of spiral tracers, hence influence the estimation of their kinematic distances. A consistent value of the distance of the Sun to the Galactic center (GC), R 0 = 8.3 kpc, was proposed by Brunthaler et al (2011), who incorporated studies on stellar orbits in the GC (Ghez et al 2008;Gillessen et al 2009) and trigonometric parallax measurements toward Sgr B2 ) and massive star forming regions (Reid et al 2009b;Brunthaler et al 2011). The circular rotation of the LSR, Θ 0 , was estimated to be 239 km s −1 .…”

Section: Introductionmentioning

confidence: 96%

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The observed spiral structure of the Milky Way

Hou

Han

2014

A&A

237

233

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Context. 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. The distances for many of them have been determined in the literature with trigonometric, photometric, and/or kinematic methods. Aims. 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. Methods. 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 Θ 0 = 220 km s −1 , and the most recent updated values of R 0 = 8.3 kpc and Θ 0 = 239 km s −1 , after velocities of tracers are modified 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.Results. 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.

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Section: Fundamental Parameter R 0 θ 0 and Solar Motionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

The observed spiral structure of the Milky Way

Hou

Han

2014

A&A

237

233

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“…However, there are only a few maser parallax measurements, and current efforts to increase their number (e.g. BeSSeL project, Brunthaler et al 2011) are naturally focused on high-mass star forming regions, more prone to maser emission. Therefore, very few of our fields have known maser emission, and none of …”

Section: Determination Of Distancesmentioning

confidence: 99%

Galactic cold cores

Montillaud

Juvela

Rivera-Ingraham

et al. 2015

A&A

160

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Context. For the project Galactic cold cores, Herschel photometric observations were carried out as a follow-up of cold regions of interstellar clouds previously identified with the Planck satellite. The aim of the project is to derive the physical properties of the population of cold sources and to study its connection to ongoing and future star formation. Aims. We build a catalogue of cold sources within the clouds in 116 fields observed with the Herschel PACS and SPIRE instruments. We wish to determine the general physical characteristics of the cold sources and to examine the correlations with their host cloud properties. Methods. From Herschel data, we computed colour temperature and column density maps of the fields. We estimated the distance to the target clouds and provide both uncertainties and reliability flags for the distances. The getsources multiwavelength source extraction algorithm was employed to build a catalogue of several thousand cold sources. Mid-infrared data were used, along with colour and position criteria, to separate starless and protostellar sources. We also propose another classification method based on submillimetre temperature profiles. We analysed the statistical distributions of the physical properties of the source samples. Results. We provide a catalogue of ∼4000 cold sources within or near star forming clouds, most of which are located either in nearby molecular complexes ( 1 kpc) or in star forming regions of the nearby galactic arms (∼2 kpc). About 70% of the sources have a size compatible with an individual core, and 35% of those sources are likely to be gravitationally bound. Significant statistical differences in physical properties are found between starless and protostellar sources, in column density versus dust temperature, mass versus size, and mass versus dust temperature diagrams. The core mass functions are very similar to those previously reported for other regions. On statistical grounds we find that gravitationally bound sources have higher background column densities (median N bg (H 2 ) ∼ 5 × 10 21 cm −2 ) than unbound sources (median N bg (H 2 ) ∼ 3 × 10 21 cm −2 ). These values of N bg (H 2 ) are higher for higher dust temperatures of the external layers of the parent cloud. However, only in a few cases do we find clear N bg (H 2 ) thresholds for the presence of cores. The dust temperatures of cloud external layers show clear variations with galactic location, as may the source temperatures. Conclusions. Our data support a more complex view of star formation than in the simple idea of a column density threshold. They show a clear influence of the surrounding UV-visible radiation on how cores distribute in their host clouds with possible variations on the Galactic scale.

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“…Similar observations have been made using the European very-long base-line radio interferometer [66], which includes three Russian antennas: Svetloe, Zelenchukskaya, and Badary. At present, these two programs are combined in the BeSSeL 5 (Bar and Spiral Structure Legacy Survey, Brunthaler, et al [67]). Radio observations of water masers at 22.2 GHz [68] are being carried out in the Japanese program VERA (VLBI Exploration of Radio Astronomy).…”

Section: H2 Molecular Clouds and Hii Zonesmentioning

confidence: 99%

The Gould Belt

Бобылев

2014

Astrophysics

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This review is devoted to studies of the Gould belt and the Local system. Since the Gould belt is the giant stellar-gas complex closest to the sun, its stellar component is characterized, along with the stellar associations and diffuse clusters, cold atomic and molecular gas, high-temperature coronal gas, and dust contained in it. Questions relating to the kinematic features of the Gould belt are discussed and the most interesting scenarios for its origin and evolution are examined.

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The Bar and Spiral Structure Legacy (BeSSeL) survey: Mapping the Milky Way with VLBI astrometry

Cited by 183 publications

References 65 publications

The observed spiral structure of the Milky Way

The observed spiral structure of the Milky Way

Galactic cold cores

The Gould Belt

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