scholarly journals Infrared emission lines from celestial sources

1965 ◽  
Vol 23 ◽  
pp. 299-302
Author(s):  
Robert J. Gould
Keyword(s):  
Fine Structure ◽  
Ground State ◽  
Hydrogen Molecule ◽  
Infrared Region ◽  
Infrared Emission ◽  
Rotational Transition ◽  
Emission Lines ◽  
H Ii Regions ◽  
Para Hydrogen ◽  
Stellar Envelopes

Some possible strong astronomical emission lines in the infrared region are discussed. The line at 12.8 microns, which results from a transition between the fine structure components of the ground state of the ion Ne+, is thought to be emitted from galactic H II regions and also possibly from extended stellar envelopes. The line at 28 microns is emitted in the J = 2 to J = 0 rotational transition in the (para) hydrogen molecule, and could be emitted from interstellar H I regions and from collapsing protostars. Estimates of the expected intensities of these astronomical emission lines are given.

Laser-rf double-resonance study of SiO+

1995 ◽  
Vol 73 (1-2) ◽  
pp. 101-105 ◽  
Author(s):  
T. J. Scholl ◽  
R. Cameron ◽  
S. D. Rosner ◽  
R. A. Holt
Keyword(s):  
Fine Structure ◽  
Ground State ◽  
Molecular Model ◽  
Double Resonance ◽  
Rotational Quantum Number ◽  
Resonance Method ◽  
Rotational Transition ◽  
Quantum Numbers ◽  
Data Yield ◽  
Π State

We used the laser-rf double resonance method to measure 15 fine structure intervals for rotational quantum numbers ranging from N = 5 to 79 of the ν = 0 level of the X2Σ+ state of SiO+. We present a molecular model, including perturbations from the A2Π state, which explains the observed strong variation of fine structure as a function of rotational quantum number. These data yield greatly improved predictions of the microwave spectrum of the ground state of SiO+. In particular we predicted the ground state rotational transition (N = 2, J = 5/2) → (N = 1, J = 3/2) to be 86 063(1) MHz, confirming that this transition is not the source of the radio line known as U86.2 at 86 243.45(40) MHz.

Infrared Emission Lines from H II Regions.

1963 ◽  
Vol 138 ◽  
pp. 1308 ◽  
Author(s):  
Robert J. Gould
Keyword(s):  
Infrared Emission ◽  
Emission Lines ◽  
H Ii Regions

scholarly journals Neon, sulphur, and argon abundances of planetary nebulae in the sub-solar metallicity Galactic anti-centre

2018 ◽  
Vol 615 ◽  
pp. A29 ◽  
Author(s):  
G. J. S. Pagomenos ◽  
J. Bernard-Salas ◽  
S. R. Pottasch
Keyword(s):  
Planetary Nebula ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Ionic Species ◽  
Infrared Emission ◽  
Emission Lines ◽  
Solar Neighbourhood ◽  
Radial Dependence ◽  
Galactic Centre ◽  
H Ii Regions

Context. Spectra of planetary nebulae show numerous fine structure emission lines from ionic species, enabling us to study the overall abundances of the nebular material that is ejected into the interstellar medium. The abundances derived from planetary nebula emission show the presence of a metallicity gradient within the disk of the Milky Way up to Galactocentric distances of ~10 kpc, which are consistent with findings from studies of different types of sources, including H II regions and young B-type stars. The radial dependence of these abundances further from the Galactic centre is in dispute. Aims. We aim to derive the abundances of neon, sulphur and argon from a sample of planetary nebulae towards the Galactic anti-centre, which represent the abundances of the clouds from which they were formed, as they remain unchanged throughout the course of stellar evolution. We then aim to compare these values with similarly analysed data from elsewhere in the Milky Way in order to observe whether the abundance gradient continues in the outskirts of our Galaxy. Methods. We have observed 23 planetary nebulae at Galactocentric distances of 8–21 kpc with Spitzer IRS. The abundances were calculated from infrared emission lines, for which we observed the main ionisation states of neon, sulphur, and argon, which are little affected by extinction and uncertainties in temperature measurements or fluctuations within the planetary nebula. We have complemented these observations with others from optical studies in the literature, in order to reduce or avoid the need for ionisation correction factors in abundance calculations. Results. The overall abundances of our sample of planetary nebulae in the Galactic anti-centre are lower than those in the solar neighbourhood. The abundances of neon, sulphur, and argon from these stars are consistent with a metallicity gradient from the solar neighbourhood up to Galactocentric distances of ~20 kpc, albeit with varying degrees of dispersion within the data.

scholarly journals The Submillimeter Wave Astronomy Satellite

1990 ◽  
Vol 123 ◽  
pp. 251-251 ◽  
Author(s):  
G.J. Melnick
Keyword(s):  
Fine Structure ◽  
Chemical Composition ◽  
Ground State ◽  
Molecular Clouds ◽  
Large Scale ◽  
Rotational Transition ◽  
Submillimeter Wave ◽  
Important Species ◽  
Structure Transition ◽  
Large Scale Survey

AbstractThe Submillimeter Wave Astronomy Satellite (SWAS) is a NASA Small-Explorer Class experiment whose objective is to study both the chemical composition and the thermal balance in dense (NH2 > 103 cm−3) molecular clouds and, by observing many clouds throughout our galaxy, relate these conditions to the processes of star formation. To conduct this study SWAS will be capable of carrying out both pointed and scanning observations simultaneously in the lines of four important species: (1) the H2O (110–101) 556.963 GHz ground-state ortho transition, (2) the O2 (3,3–1,2) 487.249 GHz transition, (3) the CI (3P1 – 3P0) 492.162 GHz ground-state fine structure transition, and (4) the 13CO (J = 5–4) 550.926 GHz rotational transition. These atoms and molecules are predicted to be among the most abundant within molecular clouds and, because they possess low-lying transitions with energy differences (ΔE/k) between 15 and 30K (temperatures typical of many molecular clouds), these species are believed to be dominant coolants of the gas as it collapses to form stars and planets. A large-scale survey in these lines is virtually impossible from any platform within the atmosphere due to telluric absorption.

Sound absorption in hydrogen gas at 77 °K

1970 ◽  
Vol 48 (3) ◽  
pp. 303-306 ◽  
Author(s):  
H. Narayana ◽  
S. B. Woods
Keyword(s):  
Relaxation Time ◽  
Hydrogen Molecule ◽  
Rotational Transition ◽  
Hydrogen Gas ◽  
Translational Energy ◽  
Pressure Measurements ◽  
Para Hydrogen ◽  
Pulse Technique ◽  
Ortho Hydrogen ◽  
Recent Experimental Work

The absorption of sound in gaseous para-hydrogen and in two mixtures of para- and ortho-hydrogen has been measured at 77 °K by a pulse technique. The frequency was 3 MHz and, by varying the gas pressure, measurements were made at frequency/pressure ratios from 3 to 45 MHz atm−1. The absorption due to relaxation between the rotational and translational energy modes was separated from the classical absorption and the relaxation time for the rotational transition J = 0 → 2 in the para-hydrogen molecule was determined. In pure para-hydrogen the isothermal relaxation time is found to be 2.21 × 10−8 s atm, but it is found to be shorter in mixtures of para- and ortho-hydrogen. The results in pure para-hydrogen are in excellent accord with recent experimental work of others but the agreement in the para–ortho mixtures is not quite so precise.

scholarly journals Observations of Infrared Fine Structure Emission

1978 ◽  
Vol 76 ◽  
pp. 127-127
Author(s):  
J.H. Lacy ◽  
F. Baas ◽  
S. Beck ◽  
C.H. Townes
Keyword(s):  
Fine Structure ◽  
Liquid Helium ◽  
Liquid Nitrogen ◽  
Planetary Nebulae ◽  
Emission Lines ◽  
H Ii Regions ◽  
Line Flux ◽  
Atmospheric Window ◽  
Fabry Perot ◽  
Absorption Features

A new spectrometer has been built for use in the 10μm atmospheric window which is substantially more sensitive than previous instruments for observations of 10]im emission and absorption features narrower than about 0.25 cm−1. Measurements have been made of fine structure emission lines in planetary nebulae as well as in galactic and extragalactic H II regions. The spectrometer consists of a liquid Helium cooled grating with a resolution of 1–4 cm−1 and a liquid Nitrogen cooled Fabry-Perot spectrometer which is scanned across the grating bandpass, resulting in a resolution of 0.1 − 0.2 cm−1. The system NEP is about , resulting in a minimum detectable line flux of about 10−19 w/cm2, with a 6″ aperture on the Lick 3m telescope.

scholarly journals Infrared Emission Lines in Planetary Nebulae

1983 ◽  
Vol 103 ◽  
pp. 79-88 ◽  
Author(s):  
Harriet L. Dinerstein
Keyword(s):  
Fine Structure ◽  
Infrared Spectroscopy ◽  
Planetary Nebulae ◽  
Infrared Emission ◽  
Emission Lines ◽  
Physical Conditions ◽  
Ionization Structure

Advances in infrared spectroscopy have led to the detection of many forbidden fine-structure emission lines in planetary nebulae. Measurements of these lines offer sensitive probes of the physical conditions and ionization structure, and lead to improved abundance determinations. This paper reviews recent observations and discusses the ways in which infrared line measurements can contribute to our knowledge of planetary nebulae.

scholarly journals Observations of infrared emission lines in the southern compact H II regions G 333.6-0.2 and G 298.2-0.3

1978 ◽  
Vol 185 (2) ◽  
pp. 179-192 ◽  
Author(s):  
D. M. Rank ◽  
H. L. Dinerstein ◽  
D. F. Lester ◽  
J. K. Bregman ◽  
D. K. Aitken ◽  
...  
Keyword(s):  
Infrared Emission ◽  
Emission Lines ◽  
H Ii Regions

The DIVING3D Project: Analysis of the nuclear region of Early-type Galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 454-456
Author(s):  
T. V. Ricci ◽  
J. E. Steiner ◽  
R. B. Menezes
Keyword(s):  
Emission Lines ◽  
H Ii Regions ◽  
Sample Type ◽  
Early Type ◽  
Integral Field Spectroscopy ◽  
Project Analysis ◽  
Line Region ◽  
Field Unit ◽  
Integral Field

AbstractIn this work, we present preliminary results regarding the nuclear emission lines of a statistically complete sample of 56 early-type galaxies that are part of the Deep Integral Field Spectroscopy View of Nuclei of Galaxies (DIVING3D) Project. All early type galaxies (ETGs) were observed with the Gemini Multi-Object Spectrograph Integral Field Unit (GMOS-IFU) installed on the Gemini South Telescope. We detected emission lines in 93% of the sample, mostly low-ionization nuclear emission-line region galaxies (LINERs). We did not find Transition Objects nor H II regions in the sample. Type 1 objects are seen in ∼23% of the galaxies.

scholarly journals 3D optical spectroscopic study of NGC 3344 with SITELLE: I. Identification and confirmation of supernova remnants

2019 ◽  
Vol 488 (1) ◽  
pp. 803-829 ◽  
Author(s):  
I Moumen ◽  
C Robert ◽  
D Devost ◽  
R P Martin ◽  
L Rousseau-Nepton ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Flux Ratio ◽  
Large Magellanic Cloud ◽  
Emission Lines ◽  
Ionization Mechanism ◽  
H Ii Regions ◽  
Nearby Galaxy ◽  
Galactocentric Distance ◽  
Ionized Gas ◽  
Diffuse Ionized Gas

ABSTRACT We present the first optical identification and confirmation of a sample of supernova remnants (SNRs) in the nearby galaxy NGC 3344. Using high spectral and spatial resolution data, obtained with the CFHT imaging Fourier transform spectrograph SITELLE, we identified about 2200 emission line regions, many of which are H ii regions, diffuse ionized gas regions, and also SNRs. Considering the stellar population and diffuse ionized gas background, which are quite important in NGC 3344, we have selected 129 SNR candidates based on four criteria for regions where the emission lines flux ratio [S ii]/H α ≥ 0.4. Emission lines of [O ii] λ3727, H β, [O iii] λλ4959,5007, H α, [N ii] λλ6548,6583, and [S ii] λλ6716,6731 have been measured to study the ionized gas properties of the SNR candidates. We adopted a self-consistent spectroscopic analysis, based on Sabbadin plots and Baldwin, Phillips & Terlevich diagrams, to confirm the shock-heated nature of the ionization mechanism in the candidates sample. With this analysis, we end up with 42 Confirmed SNRs, 45 Probable SNRs, and 42 Less likely SNRs. Using shock models, the confirmed SNRs seem to have a metallicity ranging between Large Magellanic Cloud and 2×solar. We looked for correlations between the size of the confirmed SNRs and their emission lines ratios, their galaxy environment, and their galactocentric distance: We see a trend for a metallicity gradient among the SNR population, along with some evolutionary effects.

Sign in / Sign up

Export Citation Format

Share Document