The New I.A.U. System of Galactic Coordinates (1958 Revision)

Blaauw, Adriaan; Gum, C. S.; Pawsey, J. L.; Westerhout, G.

doi:10.1093/mnras/121.2.123

Cited by 86 publications

(63 citation statements)

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“…• plane (e.g., Blaauw et al 1960;Binney 1992). In the outer galactic disk, warp is a common feature in spiral galaxies, with amplitude increasing with galactic radius (e.g., Reshetnikov & Combes 1998;Schwarzkopf & Dettmar 2001;Reshetnikov et al 2002;Kalberla & Kerp 2009;Hou & Han 2014).…”

Section: The Spiral Arm and Warp Of The Galactic Plane Traced By Co Ementioning

confidence: 99%

Molecular Clouds in the Extreme Outer Galaxy between l = 34.°75 to 45.°25

Sun

Zhang

et al. 2017

ApJS

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We present the result of an unbiased CO survey in Galactic range of 34.75• ≤l≤ 45.25• and -5.25• ≤b≤ 5.25• , and velocity range beyond the Outer arm. A total of 168 molecular clouds (MCs) are identified within the Extreme Outer Galaxy (EOG) region, and 31 of these MCs are associated with 13 CO emission. However, none of them show significant C 18 O emission under current detection limit. The typical size and mass of these MCs are 5 pc and 3×10 3 M ⊙ , implying the lack of large and massive MCs in the EOG region. Similar to MCs in the outer Galaxy, the velocity dispersions of EOG clouds are also correlated with their sizes, however, are well displaced below the scaling relationship defined by the inner Galaxy MCs. These MCs with a median Galactocentric radius of 12.6 kpc, show very different distributions from those of the MCs in the Outer arm published in our previous paper, while roughly follow the Outer Scutum-Centaurus arm defined by Dame & Thaddeus (2011). This result may provide a robust evidence for the existence of the Outer Scutum-Centaurus arm. The lower limit of the total mass of this segment is about 2.7×10 5 M ⊙ , which is about one magnitude lower than that of the Outer arm. The mean thickness of gaseous disk is about 1.45• or 450 pc, and the scale height is about 1.27• or 400 pc above the b = 0 • plane. The warp traced by CO emission is very obvious in the EOG region and its amplitude is consistent with the predictions by other warp models using different tracers, such as dust, HI and stellar components of our Galaxy.

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Section: The Spiral Arm and Warp Of The Galactic Plane Traced By Co Ementioning

confidence: 99%

Molecular Clouds in the Extreme Outer Galaxy between l = 34.°75 to 45.°25

Sun

Zhang

et al. 2017

ApJS

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“…Thus, in contrast to the Pleiades and σ Orionis, the Upper Scorpius relative star density does not reach a maximum at Z = 0 (and n A,i (d, b) and d B,i (d, l, b) do not change sign). For the Pleiades and σ Orionis, the peak of n(d)/n 0 at d sin b = −Z (when the line of sight intersects the Galactic plane) is not exactly 1.00, but there is an error of about 3% because the galactic coordinate system "is necessarily based on a Galactic plane through the Sun", which is the H i principal plane (Blaauw et al 1960). Finally, the spatial density in the direction to Upper Scorpius is lower than in the direction to the other clusters at relatively small heliocentric distances, but it becomes higher beyond about 250 pc because the OB association is approximately in the direction of the Galactic Centre.…”

Section: The Galaxy Thin-disc Modelmentioning

confidence: 99%

Contamination by field late-M, L, and T dwarfs in deep surveys

Caballero

Burgasser

Klement

2008

A&A

108

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Context. Deep photometric surveys of substellar objects in young clusters and high-redshift quasars are affected by contaminant sources at different heliocentric distances. If not correctly taken into account, the contamination may have a strong effect on the Initial Mass Function determination and on the identification of quasars. Aims. We calculate in detail the back-and foreground contamination by field dwarfs of very late spectral types (intermediate and late M, L, and T) in deep surveys and provide the data and tools for the computation. Methods. We adopt the latest models and data from the literature, which include the following: (i) a model of the Galactic thin disc by an exponential law; (ii) the length and height scales of late-type dwarfs; and (iii) the local spatial densities, absolute magnitudes, and colours of dwarfs for each spectral type. Results. We derive a simplified expression for the spatial density in the thin disc that depends on the heliocentric distance and the galactic coordinates (l, b) and integrate this into the truncated cone studied in the survey. As a practical application, we compute the numbers of L-and T-type field dwarfs in very deep (I = 21−29 mag) surveys in the direction of the young σ Orionis cluster. The increasing number of contaminants at the faintest magnitudes could inhibit the study of the opacity mass limit at M < ∼ 0.003 M in the cluster.

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“…In the inner parts of the Milky Way most of the hydrogen is confined to a narrow disk which establishes a plane of fundamental physical significance (Blaauw et al 1960). But the more we look out of the disk, the more HI we see at curious locations.…”

Section: Introductionmentioning

confidence: 99%

The Hydrogen Clouds in the Galactic Halo

Lockman¹

2004

Symp. - Int. Astron. Union

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Abstract. New 21cm observations with the Green Bank Telescope show that a significant fraction of the HI in the inner Galaxy's halo rv 1 kpc from the midplane exists in the form of discrete clouds. Some look very much like a Spitzer (1968) "standard" diffuse cloud but with their HI in two phases. They mark the transition between the neutral disk and the highly ionized halo. The dominant motion of the clouds is Galactic rotation, but some have random velocities of as much as 50 km s-l. They are part of the Galaxy and are not related to high-velocity clouds, yet their origin is obscure.

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The New I.A.U. System of Galactic Coordinates (1958 Revision)

Cited by 86 publications

References 0 publications

Molecular Clouds in the Extreme Outer Galaxy between l = 34.°75 to 45.°25

Molecular Clouds in the Extreme Outer Galaxy between l = 34.°75 to 45.°25

Contamination by field late-M, L, and T dwarfs in deep surveys

The Hydrogen Clouds in the Galactic Halo

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