scholarly journals Three-dimensional interstellar dust reddening maps of the Galactic plane

2018 ◽  
Vol 483 (4) ◽  
pp. 4277-4289 ◽  
Author(s):  
B-Q Chen ◽  
Y Huang ◽  
H-B Yuan ◽  
C Wang ◽  
D-W Fan ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Galactic Plane ◽  
Three Dimensional

scholarly journals Three-dimensional maps of interstellar dust in the Local Arm: using Gaia, 2MASS, and APOGEE-DR14

2018 ◽  
Vol 616 ◽  
pp. A132 ◽  
Author(s):  
R. Lallement ◽  
L. Capitanio ◽  
L. Ruiz-Dern ◽  
C. Danielski ◽  
C. Babusiaux ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Large Scale ◽  
Galactic Plane ◽  
Large Fraction ◽  
Complex Structure ◽  
Dust Emission ◽  
Three Dimensional ◽  
Red Giants ◽  
Photometric Calibration ◽  
The One

Context. Gaia data and stellar surveys open the way to the construction of detailed 3D maps of the Galactic interstellar (IS) dust based on the synthesis of star distances and extinctions. Dust maps are tools of broad use, also for Gaia-related Milky Way studies. Aims. Reliable extinction measurements require very accurate photometric calibrations. We show the first step of an iterative process linking 3D dust maps and photometric calibrations, and improving them simultaneously. Methods. Our previous 3D map of nearby IS dust was used to select low-reddening SDSS/APOGEE-DR14 red giants, and this database served for an empirical effective temperature- and metallicity-dependent photometric calibration in the Gaia G and 2MASS Ks bands. This calibration has been combined with Gaia G-band empirical extinction coefficients recently published, G, J, and Ks photometry and APOGEE atmospheric parameters to derive the extinction of a large fraction of the survey targets. Distances were estimated independently using isochrones and the magnitude-independent extinction KJ−Ks. This new dataset has been merged with the one used for the earlier version of dust map. A new Bayesian inversion of distance-extinction pairs has been performed to produce an updated 3D map. Results. We present several properties of the new map. A comparison with 2D dust emission reveals that all large dust shells seen in emission at middle and high latitudes are closer than 300 pc. The updated distribution constrains the well-debated, X-ray bright North Polar Spur to originate beyond 800 pc. We use the Orion region to illustrate additional details and distant clouds. On the large scale the map reveals a complex structure of the Local Arm. Chains of clouds of 2–3 kpc in length appear in planes tilted by ≃15° with respect to the Galactic plane. A series of cavities oriented along a l ≃ 60–240° axis crosses the Arm. Conclusions. The results illustrate the ongoing synergy between 3D mapping of IS dust and stellar calibrations in the context of Gaia. Dust maps provide prior foregrounds for future calibrations appropriate to different target characteristics or ranges of extinction, allowing us in turn to increase extinction data and produce more detailed and extended maps.

scholarly journals Elongated Gravity Sources as an Analytical Limit for Flat Galaxy Rotation Curves

Universe ◽  
2021 ◽  
Vol 7 (9) ◽  
pp. 346
Author(s):  
Felipe J. Llanes-Estrada
Keyword(s):  
Galactic Plane ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Small Scale ◽  
Scaling Exponent ◽  
Rotation Curves ◽  
Central Mass ◽  
Filamentary Structure ◽  
Analytical Limit ◽  
Galaxy Rotation Curves

The flattening of spiral-galaxy rotation curves is unnatural in view of the expectations from Kepler’s third law and a central mass. It is interesting, however, that the radius-independence velocity is what one expects in one less dimension. In our three-dimensional space, the rotation curve is natural if, outside the galaxy’s center, the gravitational potential corresponds to that of a very prolate ellipsoid, filament, string, or otherwise cylindrical structure perpendicular to the galactic plane. While there is observational evidence (and numerical simulations) for filamentary structure at large scales, this has not been discussed at scales commensurable with galactic sizes. If, nevertheless, the hypothesis is tentatively adopted, the scaling exponent of the baryonic Tully–Fisher relation due to accretion of visible matter by the halo comes out to reasonably be 4. At a minimum, this analytical limit would suggest that simulations yielding prolate haloes would provide a better overall fit to small-scale galaxy data.

scholarly journals Orbital elements of different Galactic population objects

1993 ◽  
Vol 153 ◽  
pp. 369-370
Author(s):  
L.P. Ossipkov ◽  
S.A. Kutuzov
Keyword(s):  
Galactic Plane ◽  
Three Dimensional ◽  
Meridional Plane ◽  
Orbital Elements ◽  
Classical Analysis ◽  
Significant Difference ◽  
Maximal Height ◽  
The Galaxy ◽  
Numerical Orbit ◽  
Component Models

The study of prevalent orbits in galactic subsystems can help us understand galactic structure and clarify its history. The classical analysis of flat orbits and metallicities of old stars led Eggen et al. (1962) to formulate the rapid collapse of the primordial Galaxy. On the other side Yoshii & Saio (1979) studied three-dimensional orbits that separate in spherical coordinates. They found the Galaxy contracted quasi-stationary after the formation of halo objects. Here we shall briefly discuss the results of numerical orbit calculations (with Merson's method) for selected galactic subsystems. The axially symmetrical two-component model of the Galaxy (Kutuzov, Ossipkov 1989) was adopted. One-component models (Barkhatova et al. 1987, Kutuzov 1988) were used also but no significant difference in orbit elements was found (Kutuzov & Ossipkov 1992). Pericenter and apocenter distances, Rp and Ra, and the maximal height of objects over the galactic plane, zm, were used as orbit elements as well as dimensionless quantities e = (Ra — Rp)/(Ra + Rp) (eccentricity) and c = 2zm/(Ra — Rp) (the flatness of box filled by orbit projection on the meridional plane).

scholarly journals Observations of the Diffuse Ultraviolet Background from the UVX Experiment On Space Shuttle

1990 ◽  
Vol 139 ◽  
pp. 227-228
Author(s):  
Richard C. Henry ◽  
Paul D. Feldman ◽  
Jayant Murthy
Keyword(s):  
Interstellar Dust ◽  
Galactic Plane ◽  
Space Shuttle ◽  
Galactic Latitude ◽  
Cosmic Background

The UVX experiment has resulted in confirmation that the diffuse ultraviolet background is low in intensity everywhere and that it is fairly uniform in intensity, both spatially and spectrally. There is no clear evidence that any significant portion of the moderate galactic latitude diffuse cosmic background originates in galactic plane starlight scattering from interstellar dust.

scholarly journals Light Echoes of Transients and Variables in the Local Universe

2012 ◽  
Vol 29 (4) ◽  
pp. 466-481 ◽  
Author(s):  
A. Rest ◽  
B. Sinnott ◽  
D. L. Welch
Keyword(s):  
Interstellar Dust ◽  
Three Dimensional ◽  
Large Magellanic Cloud ◽  
Multiple Perspectives ◽  
Local Universe ◽  
New Developments ◽  
Light Echoes ◽  
Dimensional Distribution ◽  
History Of ◽  
The Many

AbstractAstronomical light echoes, the time-dependent light scattered by dust in the vicinity of varying objects, have been recognized for over a century. Initially, their utility was thought to be confined to mapping out the three-dimensional distribution of interstellar dust. Recently, the discovery of spectroscopically useful light echoes around centuries-old supernovae in the Milky Way and the Large Magellanic Cloud has opened up new scientific opportunities to exploit light echoes.In this review, we describe the history of light echoes in the local Universe and cover the many new developments in both the observation of light echoes and the interpretation of the light scattered from them. Among other benefits, we highlight our new ability to classify outbursting objects spectroscopically, view them from multiple perspectives, obtain a spectroscopic time series of the outburst, and establish accurate distances to the source event. We also describe the broader range of variable objects with properties that may be better understood from light-echo observations. Finally, we discuss the prospects of new light-echo techniques not yet realized in practice.

scholarly journals Bipolar H II regions

2018 ◽  
Vol 617 ◽  
pp. A67 ◽  
Author(s):  
M. R. Samal ◽  
L. Deharveng ◽  
A. Zavagno ◽  
L. D. Anderson ◽  
S. Molinari ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Galactic Plane ◽  
Three Dimensional ◽  
Young Stellar Objects ◽  
Formation Processes ◽  
Two Dimensional ◽  
Stellar Objects ◽  
Flat Structures ◽  
Exciting Star

Aims. We aim to identify bipolar Galactic H II regions and to understand their parental cloud structures, morphologies, evolution, and impact on the formation of new generations of stars. Methods. We use the Spitzer-GLIMPSE, Spitzer-MIPSGAL, and Herschel-Hi-GAL surveys to identify bipolar H II regions and to examine their morphologies. We search for their exciting star(s) using NIR data from the 2MASS, UKIDSS, and VISTA surveys. Massive molecular clumps are detected near these bipolar nebulae, and we estimate their temperatures, column densities, masses, and densities. We locate Class 0/I young stellar objects (YSOs) in their vicinities using the Spitzer and Herschel-PACS emission. Results. Numerical simulations suggest bipolar H II regions form and evolve in a two-dimensional flat- or sheet-like molecular cloud. We identified 16 bipolar nebulae in a zone of the Galactic plane between ℓ ± 60° and |b| < 1°. This small number, when compared with the 1377 bubble H II regions in the same area, suggests that most H II regions form and evolve in a three-dimensional medium. We present the catalogue of the 16 bipolar nebulae and a detailed investigation for six of these. Our results suggest that these regions formed in dense and flat structures that contain filaments. We find that bipolar H II regions have massive clumps in their surroundings. The most compact and massive clumps are always located at the waist of the bipolar nebula, adjacent to the ionised gas. These massive clumps are dense, with a mean density in the range of 105 cm−3 to several 106 cm−3 in their centres. Luminous Class 0/I sources of several thousand solar luminosities, many of which have associated maser emission, are embedded inside these clumps. We suggest that most, if not all, massive 0/I YSO formation has probably been triggered by the expansion of the central bipolar nebula, but the processes involved are still unknown. Modelling of such nebula is needed to understand the star formation processes at play.

scholarly journals Three-dimensional Distribution of the Interstellar Dust in the Milky Way

2021 ◽  
Vol 906 (1) ◽  
pp. 47
Author(s):  
H.-L. Guo ◽  
B.-Q. Chen ◽  
H.-B. Yuan ◽  
Y. Huang ◽  
D.-Z Liu ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Milky Way ◽  
Three Dimensional ◽  
Dimensional Distribution

scholarly journals The kinematics of the white dwarf population from the SDSS DR12

2017 ◽  
Vol 12 (S330) ◽  
pp. 201-202
Author(s):  
B. Anguiano ◽  
A. Rebassa-Mansergas ◽  
E. García-Berro ◽  
S. Torres ◽  
K. Freeman ◽  
...  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Galactic Plane ◽  
Three Dimensional ◽  
Radial Distance ◽  
Space Velocity ◽  
Galactic Disc ◽  
Present Sample ◽  
Secular Evolution ◽  
The North

AbstractWe use the Sloan Digital Sky Survey Data Release 12, which is the largest available white dwarf catalog to date, to study the evolution of the kinematical properties of the population of white dwarfs in the Galactic disc. We derive masses, ages, photometric distances and radial velocities for all white dwarfs with hydrogen-rich atmospheres. For those stars for which proper motions from the USNO-B1 catalog are available the true three-dimensional components of the stellar space velocity are obtained. This subset of the original sample comprises 20,247 objects, making it the largest sample of white dwarfs with measured three-dimensional velocities. Furthermore, the volume probed by our sample is large, allowing us to obtain relevant kinematical information. In particular, our sample extends from a Galactocentric radial distance RG = 7.8 kpc to 9.3 kpc, and vertical distances from the Galactic plane ranging from Z = −0.5 kpc to 0.5 kpc. We examine the mean components of the stellar three-dimensional velocities, as well as their dispersions with respect to the Galactocentric and vertical distances. We confirm the existence of a mean Galactocentric radial velocity gradient, ∂〈VR〉/∂RG = −3 ± 5 km s−1 kpc−1. We also confirm North-South differences in 〈Vz〉. Specifically, we find that white dwarfs with Z > 0 (in the North Galactic hemisphere) have 〈Vz〉 < 0, while the reverse is true for white dwarfs with Z < 0. The age-velocity dispersion relation derived from the present sample indicates that the Galactic population of white dwarfs may have experienced an additional source of heating, which adds to the secular evolution of the Galactic disc.

scholarly journals The kinematics of white dwarfs from the SDSS DR12

2017 ◽  
Vol 13 (S334) ◽  
pp. 294-295
Author(s):  
E. García–Berro ◽  
G. Skorobogatov ◽  
S. Torres ◽  
B. Anguiano ◽  
A. Rebassa-Mansergas
Keyword(s):  
White Dwarfs ◽  
Galactic Plane ◽  
Galactic Disk ◽  
Three Dimensional ◽  
Radial Distance ◽  
Sloan Digital Sky Survey ◽  
Original Sample ◽  
Proper Motions ◽  
Sky Survey ◽  
Data Release

AbstractWe use the Sloan Digital Sky Survey Data Release 12, which is the largest available white dwarf catalogue to date, to study the evolution of the kinematical properties of the population of white dwarfs of the Galactic disk. We derive masses, ages, photometric distances and radial velocities for all white dwarfs with hydrogen-rich atmospheres. For those stars for which proper motions from the USNO-B1 catalogue are available, the three-dimensional components of the velocity are obtained. This subset of the original sample comprises 20,247 stars, making it the largest sample of white dwarfs with measured three-dimensional velocities. The volume probed by our sample is large, allowing us to obtain relevant kinematical information. In particular, our sample extends from a Galactocentric radial distance RG = 7.8 to 9.3 kpc, and vertical distances from the Galactic plane ranging from Z = +0.5 to –0.5 kpc.

scholarly journals Survey of Correlated FIR, HI, CO, and Radio-Continuum Emission Features in the Multi-Phase Milky Way

1998 ◽  
Vol 179 ◽  
pp. 191-193
Author(s):  
W.F. Wall ◽  
W.H. Waller
Keyword(s):  
Interstellar Dust ◽  
Galactic Plane ◽  
Line Emission ◽  
Spatial Filter ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Spatial Correlations ◽  
Gas Phases ◽  
Ir Emission ◽  
Size Scales

The interstellar medium (ISM) is rich with structure on varying size scales, reflecting its diverse energetics and dynamics. A step toward understanding this structure is to enhance the visibility of the structure on finer size scales. We present maps of a section of the Galactic plane filtered with the Median Normalized Spatial Filter (MNSF, a median smoothed map is divided into the original map), which emphasizes higher latitude emission relative to that of the plane itself (see also Waller et al., this volume, p. 194). The maps also illustrate the spatial correlations between the interstellar dust and the various gas phases: ionized, atomic, and molecular. The dust is represented by the IR emission maps of the IRAS survey, the ionized gas by the radio continuum maps at 1.4 GHz (Reich 1978, northern sky) and 2.3 GHz (Jonas & Baart 1995, southern sky), the atomic gas by surveys of the HI 21 cm line emission (Heiles & Habing 1974, Weaver & Williams 1973, Cleary et al. 1979, Kerr et al. 1986), and the molecular gas by surveys of the CO J = 1 → 0 line emission (Dame et al. 1987).

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