scholarly journals Vertical structure and kinematics of the Galactic outer disk

2019 ◽  
Vol 72 (4) ◽  
Author(s):  
Nobuyuki Sakai ◽  
Takumi Nagayama ◽  
Hiroyuki Nakanishi ◽  
Nagito Koide ◽  
Tomoharu Kurayama ◽  
...  
Keyword(s):  
Dwarf Galaxy ◽  
Oscillatory Behavior ◽  
Maximum Height ◽  
Galactocentric Distance ◽  
The North ◽  
Vertical Density ◽  
Galactic Longitude ◽  
Maser Sources ◽  
Galactic Warp ◽  
North Galactic

Abstract We report on measurements of parallax and proper motion for four 22 GHz water maser sources as part of the VERA Outer Rotation Curve project. All the sources show Galactic latitudes of >2° and Galactocentric distances of >11 kpc at the Galactic longitude range of 95° < l < 126°. The sources trace the Galactic warp reaching to 200–400 pc, and also the signature of the warp to 600 pc toward the north Galactic pole. The new results, along with previous results in the literature, show that the maximum height of the Galactic warp increases with Galactocentric distance. Also, we examined velocities perpendicular to the disk for the sample, and found oscillatory behavior between the vertical velocities and Galactic heights. This behavior suggests the existence of bending (vertical density) waves, possibly induced by a perturbing satellite (e.g., the passage of the Sagittarius dwarf galaxy).

scholarly journals On the Kinematics of Tidal Debris from Omega Cen's Progenitor Galaxy

2004 ◽  
Vol 21 (2) ◽  
pp. 237-241 ◽  
Author(s):  
Masashi Chiba ◽  
Arihiro Mizutani
Keyword(s):  
Dynamical Evolution ◽  
The Sun ◽  
Retrograde Motion ◽  
The North ◽  
Satellite Galaxy ◽  
Flat Disk ◽  
The Galaxy ◽  
Galactic Longitude ◽  
North Galactic ◽  
Kinematic Properties

AbstractThe kinematic properties of tidal debris from an orbiting Galactic satellite is presented, on the assumption that its central part once contained the most massive Galactic globular cluster, ω Cen. We simulate dynamical evolution of a satellite galaxy that follows the present-day and likely past orbits of ω Cen, and analyse the kinematic nature of their tidal debris and randomly generated Galactic stars comprising spheroidal halo and flat disk components. It is found that the debris stars show a retrograde rotation at ∼–100 km s–1, which may accord with a recently discovered stellar stream at a radial velocity of ∼300 km s–1 towards the Galactic longitude of ∼270°. These stars also contribute, only in part, to a reported retrograde motion of the outer halo in the north Galactic pole direction, without significantly modifying local halo kinematics near the Sun. The prospects for future debris searches and the implications for the early evolution of the Galaxy are briefly presented.

scholarly journals Kinematics and stellar content of the Milky Way populations toward the North Galactic Pole

2006 ◽  
Vol 451 (1) ◽  
pp. 125-139 ◽  
Author(s):  
A. Vallenari ◽  
S. Pasetto ◽  
G. Bertelli ◽  
C. Chiosi ◽  
A. Spagna ◽  
...  
Keyword(s):  
Milky Way ◽  
Stellar Content ◽  
The North ◽  
North Galactic

scholarly journals SiO maser survey of AGB stars in the North Galactic Cap

2001 ◽  
Vol 376 (1) ◽  
pp. 112-123 ◽  
Author(s):  
Y. Ita ◽  
S. Deguchi ◽  
T. Fujii ◽  
O. Kameya ◽  
M. Miyoshi ◽  
...  
Keyword(s):  
Agb Stars ◽  
The North ◽  
North Galactic

scholarly journals Brightness and Polarization of the Zodiacal Light: Results of Fixed-Position Observations from Skylab

1980 ◽  
Vol 90 ◽  
pp. 19-22
Author(s):  
J. L. Weinberg ◽  
R. C. Hahn
Keyword(s):  
Asteroid Belt ◽  
Degree Of Polarization ◽  
Zodiacal Light ◽  
Fixed Position ◽  
Vernal Equinox ◽  
The North ◽  
Celestial Pole ◽  
Total Light ◽  
North Galactic ◽  
Pioneer 10

In an earlier paper Sparrow et al. (1976) found the polarized brightness of zodiacal light to have solar color at five sky positions for which there were fixed-position observations from Skylab: north celestial pole, south ecliptic pole, vernal equinox, and two places near the north galactic pole. The brightness and degree of polarization of zodiacal light at these sky positions are derived using Pioneer 10 observations of background starlight from beyond the asteroid belt (Weinberg et al., 1974; Schuerman et al., 1976) and the assumption that the zodiacal light is also solar color in total light.

scholarly journals Identification of a Complete Sample of Northern Rosat All-Sky Survey X-Ray Sources

1998 ◽  
Vol 179 ◽  
pp. 449-449
Author(s):  
J. Krautter ◽  
I. Thiering ◽  
F.-J Zickgraf ◽  
I. Appenzeller ◽  
R. Kneer ◽  
...  
Keyword(s):  
Optical Observations ◽  
Limited Sample ◽  
Ccd Imaging ◽  
X Ray ◽  
The North ◽  
Cluster Of Galaxies ◽  
Faint Object ◽  
Sky Survey ◽  
Faint Object Spectrograph ◽  
North Galactic

We present results of the optical identification of a spatially complete, flux limited sample of about 700 ROSAT All-Sky X-ray sources contained in 6 study areas north of δ = −9° with |bII|> 20° (including one region near the North Galactic pole (NGP), another one near the North Ecliptic pole (NEP)). Countrate limits are 0.01 cts s–1 near the NEP and 0.03 cts s–1 for the other areas. The optical observations were performed at the 2.15-m telescope of the Guillermo Haro Observatory, Mexico, using the Landessterwarte Faint Object Spectrograph Camera which allows to carry out direct CCD imaging and multi-object spectroscopy. The limiting magnitude is about 19m for spectroscopy and about 23m for B and R direct imaging. Our analysis shows a dependency of the ratio of ‘extragalactic’ (e.g., AGN, cluster of galaxies) to ‘stellar’ (e.g., coronal emitters, active binaries) counterparts on NH. In the area near the NGP (low NH) ‘extragalactic’ counterparts dominate, while in the area with the highest NH ‘stellar’ counterparts dominate.

scholarly journals The Performance of Neural Networks in Astronomical Image Classification

1994 ◽  
Vol 161 ◽  
pp. 235-241
Author(s):  
S.C. Odewahn
Keyword(s):  
Neural Network ◽  
Image Classification ◽  
Sky Surveys ◽  
Pattern Recognition Techniques ◽  
The North ◽  
Astronomical Image ◽  
Sky Survey ◽  
Network Pattern ◽  
North Galactic

The use of neural network pattern recognition techniques in the field of astronomy is reviewed. In assessing the quality of image recognition derived from this method particular attention is given to the problem of star/galaxy discrimination in large digital sky surveys. A two color survey of 9 fields of the first epoch Palomar Sky Survey, centered on the North Galactic Pole, has been performed with the Minnesota Automated Plate Scanner. A set of neural network image classifiers are used to automatically perform star/galaxy discrimination. We assess the efficiency of image classification and sample completeness through comparisons with a variety of independent studies of the NGP area.

Sign in / Sign up

Export Citation Format

Share Document