scholarly journals H2O Masers in the Galactic Plane. I. Longitude 340º to the Galactic Centre

1983 ◽  
Vol 36 (3) ◽  
pp. 401 ◽  
Author(s):  
JL Caswell ◽  
RA Batchelor ◽  
JR Forster ◽  
KJ Wellington
Keyword(s):  
Galactic Plane ◽  
Main Line ◽  
Galactic Centre ◽  
Type I ◽  
Late Type

Twenty-five new H20 masers in the southern galactic plane have been discovered using a 22 GHz maser receiver on the Parkes telescope. The search was conducted at the locations of all the known 1665 MHz OH masers in the longitude range 340� through the galactic centre to 2�; of the 46 type I OH masers 38 are now found to have an H20 maser nearby; three other main-line OH emitters, possibly unusual late-type stars, also show H20 emission. We give an up-to-date tabulation of all 46 currently known H20 masers in the region which includes for completeness several H20 masers with no readily detectable associated type I OH emission.

scholarly journals Atlas of Main-line OH Masers in the Galactic Longitude Range 3° to 60°

1983 ◽  
Vol 36 (3) ◽  
pp. 417 ◽  
Author(s):  
JL Caswell ◽  
RF Haynes
Keyword(s):  
Star Formation ◽  
Circular Polarization ◽  
Galactic Plane ◽  
Hii Regions ◽  
Main Line ◽  
Late Type ◽  
Circumstellar Shells ◽  
Many Sources ◽  
First Time ◽  
Galactic Longitude

We tabulate all 55 OH main-line masers discovered to date in the galactic plane between longitude 3� and 60�. For most of these we show current spectra, which have been taken with the Parkes 64 m radio telescope, in both senses of circular polarization on the 1665 MHz and/or 1667 MHz transitions; for some sources we give new position estimates, and several sources are reported for the first time. We discuss many sources individually and note that while most of the main-line OH masers probably pinpoint compact HII regions and sites of current star formation, a few appear to be unusual varieties occurring in circumstellar shells, possibly associated with late-type stars.

scholarly journals Survey of OH Masers at 1665 MHz. II. Galactic Longitude 340o to the Galactic Centre

1983 ◽  
Vol 36 (3) ◽  
pp. 361 ◽  
Author(s):  
JL Caswell ◽  
RF Haynes
Keyword(s):  
Ground State ◽  
Galactic Plane ◽  
Line Emission ◽  
State Transitions ◽  
Galactic Centre ◽  
Emission Sources ◽  
Type I ◽  
Type Ii ◽  
Formation Type ◽  
Galactic Longitude

The galactic plane from longitude 340� through the galactic centre to longitude + 2� has been searched for OH on the 1665 MHz transition. Forty-nine OH maser emission sources were detected and these have now been studied on all four OH ground-state transitions. Most of the masers are associated with regions of star formation (type I) while three may be examples of late-type stars (type II OH/IR) with unusually strong main-line emission

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

scholarly journals Maser, infrared and optical emission for late-type stars in the Galactic plane

2017 ◽  
Vol 13 (S336) ◽  
pp. 184-186
Author(s):  
L. H. Quiroga-Nuñez ◽  
H. J. van Langevelde ◽  
L. O. Sjouwerman ◽  
Y. M. Pihlström ◽  
M. J. Reid ◽  
...  
Keyword(s):  
Galactic Plane ◽  
Population Distribution ◽  
Massive Stars ◽  
Optical Emission ◽  
Proper Motions ◽  
Late Type ◽  
Intrinsic Properties ◽  
Radio Observations ◽  
Evolved Stars

AbstractRadio astrometric campaigns using VLBI have provided distances and proper motions for masers associated with young massive stars (BeSSeL survey). The ongoing BAaDE project plans to obtain astrometric information of SiO maser stars located in the inner Galaxy. These stars are associated with evolved, mass-losing stars. By overlapping optical (Gaia), infrared (2MASS, MSX and WISE) and radio (BAaDE) sources, we expect to obtain important clues on the intrinsic properties and population distribution of late-type stars. Moreover, a comparison of the Galactic parameters obtained with Gaia and VLBI can be done using radio observations on different targets: young massive stars (BeSSeL) and evolved stars (BAaDE).

scholarly journals The evolutionary status of protostellar clumps hosting class II methanol masers

2020 ◽  
Vol 493 (2) ◽  
pp. 2015-2041 ◽  
Author(s):  
B M Jones ◽  
G A Fuller ◽  
S L Breen ◽  
A Avison ◽  
J A Green ◽  
...  
Keyword(s):  
Galactic Plane ◽  
Dust Emission ◽  
Principal Component ◽  
Far Infrared ◽  
Class Ii ◽  
Young Stellar Objects ◽  
Galactic Centre ◽  
Evolutionary Status ◽  
Methanol Maser ◽  
Methanol Masers

ABSTRACT The Methanol MultiBeam survey (MMB) provides the most complete sample of Galactic massive young stellar objects (MYSOs) hosting 6.7 GHz class II methanol masers. We characterize the properties of these maser sources using dust emission detected by the Herschel Infrared Galactic Plane Survey (Hi-GAL) to assess their evolutionary state. Associating 731 (73 per cent) of MMB sources with compact emission at four Hi-GAL wavelengths, we derive clump properties and define the requirements of an MYSO to host a 6.7 GHz maser. The median far-infrared (FIR) mass and luminosity are 630 M⊙ and 2500 L⊙ for sources on the near side of Galactic centre and 3200 M⊙ and 10000 L⊙ for more distant sources. The median luminosity-to-mass ratio is similar for both at ∼4.2 L⊙  M⊙−1. We identify an apparent minimum 70 μm luminosity required to sustain a methanol maser of a given luminosity (with $L_{70} \propto L_{6.7}\, ^{0.6}$). The maser host clumps have higher mass and higher FIR luminosities than the general Galactic population of protostellar MYSOs. Using principal component analysis, we find 896 protostellar clumps satisfy the requirements to host a methanol maser but lack a detection in the MMB. Finding a 70 μm flux density deficiency in these objects, we favour the scenario in which these objects are evolved beyond the age where a luminous 6.7 GHz maser can be sustained. Finally, segregation by association with secondary maser species identifies evolutionary differences within the population of 6.7GHz sources.

scholarly journals A Multi-Wavelength View of the XMM-Newton Galactic Plane

2014 ◽  
Vol 1 (1) ◽  
pp. 123-126
Author(s):  
Ada Nebot Gómez-Morán ◽  
Christian Motch
Keyword(s):  
Surface Density ◽  
Binary Systems ◽  
Galactic Plane ◽  
Galactic Centre ◽  
Galactic Latitude ◽  
X Ray ◽  
Model Predictions ◽  
Science Centre ◽  
Multi Wavelength ◽  
Galactic Longitude

We present an X-ray survey of the Galactic Plane conducted by the Survey Science Centre of the XMM-Newton satellite. The survey contains more than 1300 X-ray detections at low and intermediate Galactic latitudes and covering 4 deg<sup>2</sup> well spread in Galactic longitude. From a multi-wavelength analysis, using optical spectra and helped by optical and infrared photometry we identify and classify about a fourth of the sources. The observed surface density of soft X-ray (&lt;2 keV) sources decreases with Galactic latitude and although compatible with model predictions at first glance, presents an excess of stars, likely due to giants in binary systems. In the hard band (&gt;2 keV) the surface density of sources presents an excess with respect to the expected extragalactic contribution. This excess highly concentrates towards the direction of the Galactic Centre and is compatible with previous results from Chandra observations around the Galactic Centre. The nature of these sources is still unknown.

scholarly journals Statistical analysis of Galactic globular cluster type properties

2020 ◽  
Vol 495 (4) ◽  
pp. 3981-3989
Author(s):  
M Simioni ◽  
A Aparicio ◽  
G Piotto
Keyword(s):  
Globular Clusters ◽  
Principal Component ◽  
Slow Neutron ◽  
Galactic Centre ◽  
Type I ◽  
Type Ii ◽  
Relative Age ◽  
Average Complexity ◽  
Chromosome Maps ◽  
Cluster Type

ABSTRACT The analysis of pseudo-colour diagrams, the so-called chromosome maps, of Galactic globular clusters (GCs) permits to classify them into type I and type II clusters. Type II GCs are characterized by an above-the-average complexity of their chromosome maps and some of them are known to display star-to-star variations of slow neutron-capture reaction elements including iron. This is at the basis of the hypothesis that type II GCs may have an extragalactic origin and were subsequently accreted by the Milky Way. We performed a principal component analysis to explore possible correlations among various GCs parameters in the light of this new classification. The analysis revealed that cluster type correlates mainly with relative age. The cause of this relation was further investigated finding that more metal-rich type II clusters, also appear to be younger and more distant from the Galactic centre. A depletion of type II clusters for positive values of Galactic coordinate Z was also observed, with no type II clusters detected above Z ∼ 2 kpc. Type II cluster orbits also have larger eccentricities than type I ones.

A CO Survey of the Southern Galactic Plane

1981 ◽  
Vol 4 (2) ◽  
pp. 243-247 ◽  
Author(s):  
W. H. McCutcheon ◽  
B. J. Robinson ◽  
J. B. Whiteoak
Keyword(s):  
Northern Hemisphere ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Large Scale ◽  
Galactic Plane ◽  
Galactic Centre ◽  
Hydrogen Distribution ◽  
Millimetre Wave ◽  
The Galaxy ◽  
Wave Emission

Millimetre-wave emission from the CO molecule has proven to be an extremely useful probe of the cold, dense clouds of molecular hydrogen in the Galaxy. Previous studies of the large-scale distribution of CO in the galactic plane (Scoville and Solomon 1975; Burton et al. 1975; Bash and Peters 1976; Burton and Gordon 1978; Solomon et al. 1979b; Cohen et al. 1980) have all been of the northern hemisphere and primarily at longitudes 0° ≤ l ≥ 80°. These studies have revealed the striking characteristic that the CO, and by implication molecular hydrogen clouds, are concentrated in a ring extending from 4 to 8 kpc from the galactic centre. This is in sharp contrast to the atomic hydrogen distribution, which is fairly constant over the extended region from 4 to 13 kpc but correlates well with other Population I indicators.

scholarly journals Constraints for Cataclysmic Binary Evolution as Derived from Space Distributions

1984 ◽  
Vol 80 ◽  
pp. 363-385
Author(s):  
H. W. Duerbeck
Keyword(s):  
Stellar Populations ◽  
Recurrence Time ◽  
Type I ◽  
Symbiotic Stars ◽  
Late Type ◽  
Dwarf Novae ◽  
Space Density ◽  
Long Period ◽  
Mira Variables ◽  
Cataclysmic Binaries

AbstractSpace densities and galactic z-distributions of novae, recurrent novae, dwarf novae and symbiotic stars are newly determined and discussed in the context of earlier determinations. The data are then compared with the distributions of single and binary stars of possibly related types (late type giants, Mira variables, Algol systems, W UMa systems).Novae and dwarf novae have similar distributions, those of fairly young stellar populations. The observed space density of potential novae (novalike objects) indicates that the mean recurrence time of novae might be as small as a few hundred years, which leads, with given nova shell masses and mass transfer rates in the minimum stage, to a secular decrease of the masses of the components undergoing nova outbursts.Recurrent novae and symbiotic stars have distributions of older stellar populations, similar to those of late type giants and Mira variables.On the basis of galactic distribution, novae and dwarf novae are closely related and may be final stages of W UMa systems, as well as progenitors of supernovae of type I. A small fraction of W UMa systems seems to belong to an older population. If evolutionary transitions between these types of stars can be substantiated, the presence of a minority of novae and dwarf novae in globular clusters and of supernovae I in elliptical galaxies can be explained.Due to the lack of sufficiently well determined space distributions of Algol binaries, the suggestion that long-period Algol systems might be the progenitors of cataclysmic binaries can as yet neither be substantiated nor refuted. A very high space density of long-period Algol systems in the solar neighbourhood is derived. The observed space density of cataclysmic binaries could be explained by the transformation of a small percentage of the long-period Algol systems by common envelope evolution.

scholarly journals Local Stellar Kinematics from RAVE data – V. Kinematic Investigation of the Galaxy with Red Clump Stars

2014 ◽  
Vol 31 ◽  
Author(s):  
S. Karaali ◽  
S. Bilir ◽  
S. Ak ◽  
E. Yaz Gökçe ◽  
Ö. Önal ◽  
...  
Keyword(s):  
Velocity Component ◽  
Galactic Plane ◽  
Radial Distance ◽  
Vertical Direction ◽  
Space Velocity ◽  
Galactic Centre ◽  
Galactic Rotation ◽  
Stellar Kinematics ◽  
The Galaxy ◽  
Red Clump

AbstractWe investigated the space velocity components of 6 610 red clump (RC) stars in terms of vertical distance, Galactocentric radial distance and Galactic longitude. Stellar velocity vectors are corrected for differential rotation of the Galaxy which is taken into account using photometric distances of RC stars. The space velocity components estimated for the sample stars above and below the Galactic plane are compatible only for the space velocity component in the direction to the Galactic rotation of the thin disc stars. The space velocity component in the direction to the Galactic rotation (Vlsr) shows a smooth variation relative to the mean Galactocentric radial distance (Rm), while it attains its maximum at the Galactic plane. The space velocity components in the direction to the Galactic centre (Ulsr) and in the vertical direction (Wlsr) show almost flat distributions relative to Rm, with small changes in their trends at Rm ~ 7.5 kpc. Ulsr values estimated for the RC stars in quadrant 180° < l ⩽ 270° are larger than the ones in quadrants 0° < l ⩽ 90° and 270° < l ⩽ 360°. The smooth distribution of the space velocity dispersions reveals that the thin and thick discs are kinematically continuous components of the Galaxy. Based on the Wlsr space velocity components estimated in the quadrants 0° < l ⩽ 90° and 270° < l ⩽ 360°, in the inward direction relative to the Sun, we showed that RC stars above the Galactic plane move towards the North Galactic Pole, whereas those below the Galactic plane move in the opposite direction. In the case of quadrant 180° < l ⩽ 270°, their behaviour is different, i.e. the RC stars above and below the Galactic plane move towards the Galactic plane. We stated that the Galactic long bar is the probable origin of many, but not all, of the detected features.

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