scholarly journals The ORFEUS Far Ultraviolet Spectrum of the LMC Binary Star HDE 269546

1997 ◽  
Vol 166 ◽  
pp. 517-520
Author(s):  
H. Widmann ◽  
G. Krämer ◽  
I. Appenzeller ◽  
J. Barnstedt ◽  
A. Fromm ◽  
...  
Keyword(s):  
Molecular Hydrogen ◽  
Milky Way ◽  
Galactic Halo ◽  
Binary Star ◽  
Ultraviolet Spectrum ◽  
Echelle Spectrograph ◽  
Hot Gas ◽  
First Results ◽  
Far Ultraviolet ◽  
First Time

AbstractFar UV high resolution spectra of 3 LMC and SMC stars were obtained with the Echelle spectrograph during the second ORFEUS mission in Dec. 1996. We present the first results from observations of the LMC star HDE 269546. We find definitely components of very hot gas identified as OVI and SVI absorption in the galactic halo of the Milky Way and in the LMC. Additionally, more than 30 ions of the most abundant elements in different stages of ionization can be identified in both our galaxy and the LMC. For the first time we can identify a significant absorption component of molecular hydrogen in the ORFEUS II Echelle spectrum with a redshift of 200 km s−1, doubtlessly to be attributed to the LMC.

scholarly journals AGN Spectra as Seen by the Infrared Space Observatory: First Results

1997 ◽  
Vol 159 ◽  
pp. 333-336
Author(s):  
D. Lutz ◽  
R. Genzel ◽  
E. Sturm ◽  
A.F.M. Moorwood ◽  
E. Oliva ◽  
...  
Keyword(s):  
Fine Structure ◽  
Short Wavelength ◽  
Molecular Hydrogen ◽  
Molecular Gas ◽  
Space Observatory ◽  
Infrared Space Observatory ◽  
First Results ◽  
External Galaxies ◽  
First Time ◽  
Fine Structure Lines

AbstractWe discuss 2.5–45 µm spectra of the Circinus galaxy and of Cen A, obtained with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory. The large number of detected ionic fine structure lines, observable also in visually obscured sources, provides strong constraints on the shape of the ionizing spectrum, which is found to exhibit a UV bump peaking at ~ 70 eV in the case of Circinus. Pure rotational emission of molecular hydrogen, directly probing warm molecular gas, can for the first time be detected in external galaxies.

scholarly journals The Fuse Survey of O VI in and near the Milky Way

2004 ◽  
Vol 217 ◽  
pp. 147-153
Author(s):  
B. D. Savage ◽  
B. P. Wakker ◽  
K. R. Sembach ◽  
P. Richter ◽  
M. Meade
Keyword(s):  
High Velocity ◽  
Polar Region ◽  
Milky Way ◽  
Thick Disk ◽  
Hot Gas ◽  
Tidal Interactions ◽  
Halo Stars ◽  
Absorbing Layer ◽  
Far Ultraviolet ◽  
Gas Interactions

We summarize the results of the Far-Ultraviolet Spectroscopic Explorer (FUSE) program to study O VI in the Milky Way halo. Spectra of 100 extragalactic objects and two distant halo stars are analyzed to obtain measures of O VI absorption along paths through the Milky Way thick disk/halo and beyond. Strong O VI absorption over the velocity range from −100 to 100 km s−1 reveals a widespread but highly irregular distribution of O VI, implying the existence of substantial amounts of hot gas with T~3×105 K in the Milky Way thick disk/halo. The overall distribution of O VI can be described by a plane-parallel patchy absorbing layer with an average O VI mid-plane density of no(O VI) = 1.7×10−8 cm−3, an exponential scale height of ~2.3 kpc, and a ~0.25 dex excess of O VI in the northern Galactic polar region. Approximately 60 percent of the sky is covered by high velocity O VI with |vLSR|>100 km s−1. This high velocity O VI traces a variety of phenomena in and near the Milky Way including outflowing material from the Milky Way, tidal interactions with the Magellanic Clouds, accretion of gas onto the Milky Way, and warm/hot gas interactions in a highly extended (>70 kpc) Galactic corona or with hot intergalactic gas in the Local Group.

A Discussion on solar studies with special reference to space observations - A high resolution solar ultraviolet spectrum between 200 and 220 nm

1971 ◽  
Vol 270 (1202) ◽  
pp. 29-46 ◽  
Keyword(s):  
High Resolution ◽  
Solar Spectrum ◽  
Ultraviolet Spectrum ◽  
Absorption Feature ◽  
Intensity Analysis ◽  
Echelle Spectrograph ◽  
Broad Absorption ◽  
First Time ◽  
Solar Ultraviolet ◽  
The Continuum

A high resolution solar spectrum in the range 200 to 220 nm has been recorded with an echelle spectrograph launched in, a sun-pointing Skylark rocket. The data have been reduced and are presented as intensity-wavelength plots together with a wavelength list and proposed identifications. A broad absorption feature at 212.4 nm is assigned to a single source and an intensity analysis confirms this to be the non-resonance Sii line at 212.412 nm. The discontinuity in the continuum intensity near 208.7 nm is revealed with high resolution for the first time and is assigned to the photoionization edge of A11. An analysis shows that its intensity drop and wavelength position can only be explained by adjustments to the solar model in the region 0.001 < T 5000 < 0.2.

scholarly journals Hot gas in Milky Way size galaxies at z=0

2016 ◽  
Vol 11 (S321) ◽  
pp. 72-74
Author(s):  
Santi Roca-Fàbrega ◽  
Pedro Colin ◽  
Octavio Valenzuela ◽  
Francesca Figueras ◽  
Yair Krongold
Keyword(s):  
Dark Matter ◽  
Column Density ◽  
Milky Way ◽  
Galactic Halo ◽  
Careful Analysis ◽  
Dark Matter Halo ◽  
Hot Gas ◽  
Satellite Galaxy ◽  
Real Distribution ◽  
Axisymmetric Structures

AbstractWe present a new set of cosmological Milky Way size galaxy simulations using ART. In our simulations the main system has been evolved inside a 28 Mpc cosmological box with a spatial resolution of 109 pc. At z=0 our systems have an Mvir = 6 − 8 × 1011 M⊙. In several of out models we have observed how a well defined disk is formed inside the dark matter halo and the overall amount of gas and stars is comparable with MW observations. Several non-axisymmetric structures arise out of the disk: spirals, bars and also a warp. We have also observed that a huge reservoir of hot gas is present at large distances from the disk, embedded in the dark matter halo region, accounting for only a fraction of the ”missing baryons”. Gas column density, emission (EM) and dispersion (DM) measure have been computed from inside the simulated disk at a position of 8 kpc from the center and in several directions. Our preliminary results reveal that the distribution of hot gas is non-isotropic according with observations (Gupta et al. 2012, Gupta et al. 2014). Also its metallic content presents a clear bimodality what is a consequence of a recent accretion of a satellite galaxy among others. After a careful analysis we confirm that due to the anisotropy in the gas distribution a new observational parameter needs to be defined to recover the real distribution of hot gas in the galactic halo (Roca-Fàbrega et al. 2016).

scholarly journals The H i Column Density Distribution of the Galactic Disk and Halo

2021 ◽  
Vol 923 (1) ◽  
pp. 50
Author(s):  
David M. French ◽  
Andrew J. Fox ◽  
Bart P. Wakker ◽  
Nicolas Lehner ◽  
J. Christopher Howk ◽  
...  
Keyword(s):  
Density Distribution ◽  
Column Density ◽  
Milky Way ◽  
Galactic Halo ◽  
Galactic Disk ◽  
Galactic Latitude ◽  
Low Velocity ◽  
Neutral Gas ◽  
Robust Measurements ◽  
Far Ultraviolet

Abstract We present a census of neutral gas in the Milky Way disk and halo down to limiting column densities of N(H i) ∼ 1014 cm−2 using measurements of H i Lyman series absorption from the Far Ultraviolet Spectroscopic Explorer. Our results are drawn from an analysis of 25 AGN sight lines spread evenly across the sky with Galactic latitude ∣b∣ ≳ 20°. By simultaneously fitting multi-component Voigt profiles to 11 Lyman series absorption transitions covered by FUSE (Lyβ–Lyμ) plus HST measurements of Lyα, we derive the kinematics and column densities of a sample of 152 H i absorption components. While saturation prevents accurate measurements of many components with column densities 17 ≲ log N(H i) ≲ 19, we derive robust measurements at log N(H i) ≲ 17 and log N(H i) ≳ 19. We derive the first ultraviolet H i column density distribution function (CDDF) of the Milky Way, both globally and for low-velocity (ISM), intermediate-velocity clouds (IVCs), and high-velocity clouds (HVCs). We find that IVCs and HVCs show statistically indistinguishable CDDF slopes, with β IVC = − 1.01 − 0.14 + 0.15 and β HVC = − 1.05 − 0.06 + 0.07 . Overall, the CDDF of the Galactic disk and halo appears shallower than that found by comparable extragalactic surveys, suggesting a relative abundance of high column density gas in the Galactic halo. We derive the sky-covering fractions as a function of H i column density, finding an enhancement of IVC gas in the northern hemisphere compared to the south. We also find evidence for an excess of inflowing H i over outflowing H i, with −0.88 ± 0.40 M ⊙ yr−1 of HVC inflow versus ≈0.20 ± 0.10 M ⊙ yr−1 of HVC outflow, confirming an excess of inflowing HVCs seen in UV metal lines.

The ORFEUS far ultraviolet spectrum of the LMC binary star HDE 269546

2008 ◽  
pp. 517-520
Author(s):  
H. Widmann ◽  
G. Krämer ◽  
I. Appenzeller ◽  
J. Barnstedt ◽  
A. Fromm ◽  
...  
Keyword(s):  
Binary Star ◽  
Ultraviolet Spectrum ◽  
Far Ultraviolet

scholarly journals A Far-ultraviolet Fluorescent Molecular Hydrogen Emission Map of the Milky Way Galaxy

2017 ◽  
Vol 231 (2) ◽  
pp. 21 ◽  
Author(s):  
Young-Soo Jo ◽  
Kwang-Il Seon ◽  
Kyoung-Wook Min ◽  
Jerry Edelstein ◽  
Wonyong Han
Keyword(s):  
Molecular Hydrogen ◽  
Milky Way ◽  
Milky Way Galaxy ◽  
Hydrogen Emission ◽  
Far Ultraviolet

scholarly journals Line observations of the 30-Dor complex and N159A5 with the MPE imaging NIR spectrometer FAST

1991 ◽  
Vol 148 ◽  
pp. 205-206 ◽  
Author(s):  
A. Krabbe ◽  
J. Storey ◽  
V. Rotaciuc ◽  
S. Drapatz ◽  
R. Genzel
Keyword(s):  
Spatial Resolution ◽  
Molecular Hydrogen ◽  
Near Infrared ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Emission Lines ◽  
Resolving Power ◽  
Max Planck ◽  
First Time ◽  
Infrared Array

Images with subarcsec spatial resolution in the light of near-infrared atomic (Bry) and molecular hydrogen H2 (S(1) v=1-0) emission lines were obtained for some extended, pointlike objects in the Large Magellanic Cloud (LMC) for the first time. We used the Max-Planck-Institut für extraterrestrische Physik (MPE) near-infrared array spectrometer FAST (image scale 0.8”/pix, spectral resolving power 950) at the ESO/MPI 2.2m telescope, La Silla. We present some results on the 30-Dor complex and N159A5.

scholarly journals Measurement of the cosmic ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite

2019 ◽  
Vol 5 (9) ◽  
pp. eaax3793 ◽  
Author(s):  
◽  
Q. An ◽  
R. Asfandiyarov ◽  
P. Azzarello ◽  
P. Bernardini ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Cosmic Radiation ◽  
Precise Measurement ◽  
Milky Way ◽  
Spectral Feature ◽  
Dark Matter Particle ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Proton Spectrum ◽  
First Time

The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 1/2 years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

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