scholarly journals An infrared survey of the Southern Milky Way

1964 ◽  
Vol 20 ◽  
pp. 160-167 ◽  
Author(s):  
B. E. Westerlund
Keyword(s):  
Spectral Region ◽  
Milky Way ◽  
Galactic Plane ◽  
Galactic Structure ◽  
The Sun ◽  
Ob Stars ◽  
Objective Prism ◽  
Blue Spectral Region ◽  
Infrared Survey

The determination by optical means of the galactic structure at great distances from the Sun is becoming more and more important. Most optical investigations, using ordinary techniques — objective-prism survey in the blue spectral region + UBV photometry — do not reach very far out owing to the heavy obscuration in most directions in the galactic plane. Only a few very luminous OB stars and some rare supergiants have been identified in some selected regions at distances exceeding 4 kpc.

scholarly journals Optical Observations of Galactic and Extragalactic Light: Implications for Galactic Structure

1990 ◽  
Vol 139 ◽  
pp. 21-34
Author(s):  
Gary N. Toller
Keyword(s):  
Galactic Plane ◽  
Historical Review ◽  
Interstellar Extinction ◽  
Galactic Structure ◽  
Optical Observations ◽  
The Sun ◽  
Color Distribution ◽  
Background Light ◽  
Dominant Component ◽  
Spiral Arm

A historical review of integrated starlight, diffuse galactic light, and extragalactic light studies is presented. Together, these components compose the “background light.” Methods ranging from star counts to space-based photometric surveys have succeeded in quantifying the contribution of each component of the background. Integrated starlight is the dominant component. The contribution of diffuse galactic light in the general interstellar medium peaks slightly off the galactic plane and declines toward higher latitudes. The extragalactic light has been determined from both galaxy counts and photometric methods. The blue and red intensity and B–R color distribution of background light have been mapped. The relation between galactic structure and background light measurements is established. The distribution of interstellar extinction is the primary regulator of the brightness. However, spiral arm and stellar distribution effects are discerned in Carina and Sagittarius. The sun lies 13 pc north of the galactic plane as defined by brightness and dust distributions.

scholarly journals Radio Stars of the SKA

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 119
Author(s):  
Bin Yu ◽  
Albert Zijlstra ◽  
Biwei Jiang
Keyword(s):  
Radio Emission ◽  
Milky Way ◽  
Galactic Plane ◽  
High Sensitivity ◽  
Hii Regions ◽  
Be Stars ◽  
M Dwarfs ◽  
Ob Stars ◽  
5 Ghz ◽  
Radio Stars

Radio emission from stars can be used, for example, to study ionized winds or stellar flares. The radio emission is faint and studies have been limited to few objects. The Square Kilometer Array (SKA) brings a survey ability to the topic of radio stars. In this paper we investigate what the SKA can detect, and what sensitivity will be required for deep surveys of the stellar Milky Way. We focus on the radio emission from OB stars, Be stars, flares from M dwarfs, and Ultra Compact HII regions. The stellar distribution in the Milky Way is simulated using the Besançon model, and various relations are used to predict their radio flux. We find that the full SKA will easily detect all UltraCompact HII regions. At the limit of 10 nJy at 5 GHz, the SKA can detect 1500 Be stars and 50 OB stars per square degree, out to several kpc. It can also detect flares from 4500 M dwarfs per square degree. At 100 nJy, the numbers become about 8 times smaller. SKA surveys of the Galactic plane should be designed for high sensitivity. Deep imaging should consider the significant number of faint flares in the field, even outside the plane of the Milky Way.

scholarly journals Progress report on the Cleveland-Chile survey for southern OB stars

1970 ◽  
Vol 38 ◽  
pp. 276-277
Author(s):  
C. B. Stephenson ◽  
N. Sanduleak
Keyword(s):  
Milky Way ◽  
Progress Report ◽  
The State ◽  
Published Data ◽  
Ob Stars ◽  
Systematic Survey ◽  
The North ◽  
Objective Prism

From some standpoints it should seem surprising that not all of the OB stars of our Galaxy that can be identified to a feasible limiting magnitude (say 12–13) by conventional objective prism techniques have yet been so identified, but this is in fact the state of our published data. Some people here will recall that such a systematic survey for the northern Milky Way was carried out several years ago jointly by the Hamburg and Warner and Swasey Observatories. Now at the Warner and Swasey Observatory we are extending this northern survey into the southern Milky Way that could not be reached from the north, and we are making this extension as homogeneous as possible with respect to the northern survey.

scholarly journals III. Local Galactic Structure

1985 ◽  
Vol 19 (1) ◽  
pp. 407-409
Keyword(s):  
Milky Way ◽  
Gamma Ray ◽  
Galactic Structure ◽  
Solar Neighbourhood ◽  
The Sun ◽  
X Ray ◽  
The Galaxy

This section contains work dealing with the Milky Way characteristics in the solar neighbourhood and supported by observations with wavelengths shorter than 1 mm. Thus, results are collected from gamma-ray, X-ray, UV, optical and IR observations in the different subsections. These are (1) the volume closest to the sun, (2) more distant objects at low galactic latitudes, and (3) objects at high galactic latitudes. Overall properties of the Galaxy and evolutionary effects are presented in Section IV.

Kinematics of the Milky Way Thick disk in solar neighborhood

2021 ◽  
Author(s):  
K. Vieira ◽  
V. Korchagin ◽  
A. Lutsenko
Keyword(s):  
Milky Way ◽  
Galactic Plane ◽  
Thick Disk ◽  
Solar Neighborhood ◽  
Stellar Disk ◽  
The Sun ◽  
Complete Sample ◽  
Two Component ◽  
Thick Disks ◽  
Red Giant

Using GAIA EDR3 catalog, we present the detailed analysis of the two-component Milky Way stellar disk in the solar neighborhood. To determine the kinematical properties of the thin and of the Thick disks, we select the complete sample of about 278,000 evolved red giant branch (RGB) stars distributed in the cylinder of 1 kpc radius and 0.5 kpc height centered at the Sun. We measured the following mean velocities and dispersions for the thin and the Thick disks, respectively: [Formula: see text][Formula: see text]km s[Formula: see text] with [Formula: see text][Formula: see text]km s[Formula: see text], and [Formula: see text][Formula: see text]km s[Formula: see text] with [Formula: see text][Formula: see text]km s[Formula: see text]. Errors in mean velocities and dispersions are all less than 1[Formula: see text]km s[Formula: see text]. Same values were computed on much smaller subsamples of our Gaia data with RAVE DR5 [Fe/H] values, from which a metallicity selection was added. Results are basically the same. We find that up to 500 pc height above/below the galactic plane, Thick disk stars comprise about half the stars of the disk. We also find evidence of a substructure in [Formula: see text] versus [Formula: see text] in the thick disk population mostly that would give support to the accretion scenario for the formation of the thick disk.

scholarly journals Radial velocities of early-type stars

1970 ◽  
Vol 38 ◽  
pp. 290-290
Author(s):  
J. P. Kaufmann
Keyword(s):  
Velocity Gradient ◽  
Milky Way ◽  
Radial Velocities ◽  
Circular Motion ◽  
The Sun ◽  
Spectral Classification ◽  
Early Type ◽  
Objective Prism ◽  
Minimum Distances ◽  
Early Type Stars

With the Fehrenbach objective prism radial velocities of about 700 stars of type B0 to A0 were determined in two fields of the Southern Milky Way (lII = 295° bII = −0.6°; lII = 320° bII = −2.5°), with a mean error of ±20 km s−1. An additional photographic UBV-photometry with plates of the ADH-telescope at Boyden Observatory was accomplished. Minimum distances for the stars resulted from absorption-corrected magnitudes and a MK-spectral classification. About 200 stars lay at distances greater than 1.5 kpc from the sun. The largest distances determined were 5 kpc. From the radial velocities and distances circular velocities were derived and plotted against galactocentric distances R. Even within the possible error limits a positive velocity gradient showed up in the range 8 kpc < R < 9.5 kpc, which French authors had already found for the region 10.5 kpc < R < 12.5 kpc. If there do not exist significant deviations from circular motion for these stars, a conformity with Schmidt's 1965 model cannot be obtained.

scholarly journals A Low-Dispersion, Near-Infrared Survey for Galactic M Supergiants

1986 ◽  
Vol 116 ◽  
pp. 123-124
Author(s):  
D. J. MacConnell ◽  
R. F. Wing ◽  
E. Costa
Keyword(s):  
Interstellar Dust ◽  
Near Infrared ◽  
Galactic Plane ◽  
Galactocentric Distance ◽  
The Galaxy ◽  
Red Supergiants ◽  
Objective Prism ◽  
Low Dispersion ◽  
Infrared Survey

While there have been many surveys for luminous, blue galactic stars and their numbers can be considered somewhat complete, such is not the case for red supergiants (see e.g. Humphreys and McElroy 1984). One result of this incompleteness is that the ratios B/R and WR/R, often used as diagnostics for evolutionary models of massive stars and the variation of the ratios with galactocentric distance, are not well known for the Galaxy. In an attempt to improve the statistics, the first author began an objective-prism survey within 6 deg of the southern galactic plane using I-N plates. The dispersion is 3400 A/mm at the A-band, and the spectra cover the range 6800–8800 A; the deepest plates reach ir mag ∼13. The detection of possible M supergiants on such plates was first discussed by Nassau, et al. (1954) and depends on the presence of TiO at 7054 A and a spectrum sharply tapered to the blue. For supergiants, this shape results from integration of interstellar dust over a long path-length, but any sample of red stars with tapered spectra contains M giants in heavily-obscured regions and S stars; thus follow-up observations of the candidate stars are necessary.

The SRC Near-Infrared Survey of the Galactic Plane

1981 ◽  
Vol 4 (2) ◽  
pp. 251-254 ◽  
Author(s):  
M. Hartley ◽  
J. A. Dawe
Keyword(s):  
Near Infrared ◽  
Milky Way ◽  
Galactic Plane ◽  
Magellanic Clouds ◽  
Schmidt Telescope ◽  
Photographic Paper ◽  
Infrared Survey

In 1975, Hoessel, Elias, Wade and Huchra commenced a near infrared survey of 80 fields in the northern Milky Way with the Palomar 1.2 m Schmidt telescope, (Hoessel et al. 1979). This has now been issued as an atlas reproduced in the form of photographic paper prints. In 1977, the SRC 1.2 m Schmidt telescope at Siding Spring was authorized to commence a complementary survey of the southern Milky Way, consisting of the 151 ESO/SRC survey fields which have centres within 10° of the galactic plane and negative declinations (see Fig. 1). A further 12 fields have subsequently been added to the survey to permit coverage of the Large and Small Magellanic Clouds.

A comparison of the classification systems of luminous stars in the northern Milky Way II and IV, for stars assigned two-dimensional spectral types from objective-prism plates

1966 ◽  
Vol 24 ◽  
pp. 70-73
Author(s):  
C. B. Stephenson
Keyword(s):  
Milky Way ◽  
Classification Systems ◽  
Two Dimensional ◽  
Joint Project ◽  
Ob Stars ◽  
Luminosity Class ◽  
Objective Prism ◽  
The Mean ◽  
The Difference ◽  
Hydrogen Lines

For some years a survey for early-type luminous stars in the northern Milky Way has been underway at the Warner and Swasey Observatory and the Hamburg Observatory, as a joint project by the two institutions (1). With the aid of ultraviolet-transmitting objective prisms (Schott UBK7 glass), it has been possible at both institutions to recognize OB stars at a dispersion of about 600Å/mm. Moreover, the appearance of the Balmer discontinuity at low dispersion affords a valuable aid to two-dimensional classification of stars of late B to late F types (2, 3). These two-dimensional classifications, which are based essentially upon the appearance of the continuum (especially the Balmer discontinuity), the hydrogen lines, the K line, and the G band, are assigned in the MK classification nomenclature since they are well correlated with classifications made by means of the real MK classification criteria. The quality of the correlation depends upon location in the HR diagram, but the random probable error appears to be upward of one MK luminosity class and about a quarter of a full letter division in temperature class, except that luminosity class IV is nowhere well distinguished from class V, and class Iab is not really well distinguished from Ia and Ib.The present Cleveland system of assigning two-dimensional spectral types to stars from ultraviolet-included objective-prism plates tends to assign lower luminosities than those of the LS II (–LS I?) system. This fact alone accounts for certainly most of the difference between the numbers of stars assigned two-dimensional spectral types in LS II and in LS IV. The origin of this systematic difference of over a luminosity class is not well explained, but the difference is hardly alarming. The numbers of OB stars in the two catalogues are quite comparable and this is consistent with the fact that no classification system difference for OB stars is known to exist between these two catalogues.Slit spectrograms so far available support the belief that LS IV agrees better in the mean with the MK system than does LS II, though LS IV may also be slightly overluminous in the mean. There is one factor always tending to confuse the transformation from this objective-prism system to MK spectral types: stars having abnormally strong Balmer discontinuities will usually be included in our catalogues with some kind of MK classification, While those with abnormally weak Balmer discontinuities will more often be excluded or assigned to the OB group. This problem is by no means so serious as to detract significantly from the desirability of making objective-prism surveys that pay special heed to the Balmer discontinuity.

scholarly journals Some Results of Classification of Stars in Kapteyn Areas Applied to Galactic Structure in NGP

1977 ◽  
Vol 4 (2) ◽  
pp. 49-50 ◽  
Author(s):  
E. K. Kharadze ◽  
R. A. Bartaya
Keyword(s):  
Galactic Plane ◽  
High Accuracy ◽  
Galactic Structure ◽  
The Other ◽  
Two Dimensional ◽  
Other Hand ◽  
Objective Prism

The observational base of our investigation consists of a two-dimensional MK classification of about 11.000 stars in the 42 Kapteyn Areas situated along the gal.lat-s from −17° up to +72° and 200 Ap, Am stars discovered in the same KA. The dispersion of the applied objective-prism spectra is 160 Â per mm. The data are of high accuracy, close to the Michigan level, and uniformity, which make them reliable. The limit is close to the 12-th ph.mg.The general conclusion of the undoubted importance is stated: the galactic concentration of dwarfs is closer than it had been assumed until now; on the other hand - the giants are not so closely concentrated to the galactic plane as it has been accepted.

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