scholarly journals A Decoupled Nucleus in NGC 1052

1995 ◽  
Vol 164 ◽  
pp. 438-438
Author(s):  
O.K. Sil'chenko
Keyword(s):  
Absorption Line ◽  
Spectral Range ◽  
Equivalent Width ◽  
Two Dimensional ◽  
Ionized Gas ◽  
Radial Profiles ◽  
Line Equivalent Width

The central part of NGC 1052 has been observed at the prime focus of the 6m telescope with the Multi-Pupil Spectrophotometer equipped with a two-dimensional IPCS. Ninety-nine spectra over the central 14.5″x11″ are registered in the spectral range of λλ4700 – 5400 AA and are used to map ionized-gas velocities (by [OIII]λ5007) and to derive radial profiles of absorption-line equivalent width for MgIλA5175, FeIλ5270, and Hβ.

scholarly journals The effects of diffuse ionized gas and spatial resolution on metallicity gradients: TYPHOON two-dimensional spectrophotometry of M83

2019 ◽  
Vol 487 (1) ◽  
pp. 79-96 ◽  
Author(s):  
Henry Poetrodjojo ◽  
Joshua J D’Agostino ◽  
Brent Groves ◽  
Lisa Kewley ◽  
I-Ting Ho ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Systematic Study ◽  
Surface Brightness ◽  
H Ii Regions ◽  
Two Dimensional ◽  
Ionized Gas ◽  
Data Cubes ◽  
Radial Profiles ◽  
Diffuse Ionized Gas ◽  
Spectrophotometric Data

Abstract We present a systematic study of the diffuse ionized gas (DIG) in M83 and its effects on the measurement of metallicity gradients at varying resolution scales. Using spectrophotometric data cubes of M83 obtained at the 2.5m duPont telescope at Las Campanas Observatory as part of the TYPHOON programme, we separate the H ii regions from the DIG using the [S ii]/H α ratio, HIIphot (H ii-finding algorithm), and the H α surface brightness. We find that the contribution to the overall H α luminosity is approximately equal for the H ii and DIG regions. The data is then rebinned to simulate low-resolution observations at varying resolution scales from 41 pc up to 1005 pc. Metallicity gradients are measured using five different metallicity diagnostics at each resolution. We find that all metallicity diagnostics used are affected by the inclusion of DIG to varying degrees. We discuss the reasons why the metallicity gradients are significantly affected by DIG using the H ii dominance and emission line ratio radial profiles. We find that applying the [S ii]/H α cut will provide a closer estimate of the true metallicity gradient up to a resolution of 1005 pc for all metallicity diagnostics used in this study.

scholarly journals Interaction Between A Stellar Wind and the Ionized Gas in N120 (LMC)

1989 ◽  
Vol 120 ◽  
pp. 194-194
Author(s):  
A. Laval ◽  
M. Rosado ◽  
J. Boulesteix ◽  
Y.P. Georgelin ◽  
M. Marcelin ◽  
...  
Keyword(s):  
Spectral Range ◽  
Stellar Wind ◽  
Free Spectral Range ◽  
Photon Counting ◽  
Field Of View ◽  
Two Dimensional ◽  
Total Field ◽  
Ionized Gas ◽  
Counting System ◽  
Being There

The western part of the nebula N120, in the LMC, was observed in Hα with the equipment CIGALE at ESO. This equipment consists mainly of a scanning Perot-Fabry interferometer and a two-dimensional photon counting system. The spectral step used here is 0.41 Ǡover free spectral range of 8.24 Ǡ. The total field of view of 7’ x 7’ is covered by 256 x 256 pixels (each pixel being there 2.6” x 2.6”).

scholarly journals Further developments in star cluster spectral libraries

2009 ◽  
Vol 5 (S266) ◽  
pp. 347-350
Author(s):  
Andrea V. Ahumada ◽  
Juan J. Clariá ◽  
Eduardo Bica ◽  
Andrés E. Piatti ◽  
João F. C. Santos ◽  
...  
Keyword(s):  
Spectral Range ◽  
Equivalent Width ◽  
Template Matching ◽  
Magellanic Cloud ◽  
Star Cluster ◽  
Open Clusters ◽  
Stellar Clusters ◽  
Colour Excess ◽  
Matching Procedure ◽  
Spectral Libraries

AbstractWe present flux-calibrated integrated spectra in the optical spectral range of Galactic open clusters (GOCs) and Magellanic Cloud (MC) stellar clusters (SCs) obtained at CASLEO (Argentina). The SC parameters were derived using the equivalent-width (EW) method and the template-matching procedure by comparing the line strengths and continuum distribution of the cluster spectra with those of template spectra with known parameters. MC cluster reddening values were also estimated by interpolation between the available extinction maps. The derived ages for the GOCs range from 3 Myr to 4 Gyr, while those of the MC SCs vary from 3 Myr to 7 Gyr. E(B−V) colour-excess values in the MCs appear to be all lower than 0.17 mag, while those of the GOCs range from 0.00 to 2.40 mag. The present data led us to upgrade the spectral libraries of reference spectra or templates of solar and MC metallicities.

scholarly journals Lithium Abundance and Spacial Distribution of T Tauri Stars

1992 ◽  
Vol 150 ◽  
pp. 395-397
Author(s):  
Jane Gregorio-Hetem ◽  
Jacques R.D. Lépine
Keyword(s):  
Star Formation ◽  
Equivalent Width ◽  
Molecular Cloud ◽  
Resonance Line ◽  
T Tauri Stars ◽  
Lithium Abundance ◽  
Active Star ◽  
T Tauri ◽  
Star Formation Regions ◽  
Line Equivalent Width

We determined temperatures and Lithium 6707 A resonance line equivalent width of a sample of 62 T Tauri stars. Lithium abundances were then estimated by using a grid of curves of growth. The lithium abundance is shown to decrease with the distance of the stars to the nearest dense core of a molecular cloud. This effect is interpreted as being due to the ages of the stars, the youngest ones being closer to still active star formation regions.

scholarly journals Observations of Highly-Ionized Interstellar Iron

1984 ◽  
Vol 81 ◽  
pp. 189-191
Author(s):  
L.M. Hobbs
Keyword(s):  
Radial Velocity ◽  
Absorption Line ◽  
Equivalent Width ◽  
Column Density ◽  
Light Path ◽  
Interstellar Gas ◽  
X Ray ◽  
X Ray Background ◽  
Multi Phase ◽  
No Absorption

AbstractThe spectra of 24 stars, including 5 at distances d < 200 pc, have been observed in the regions of the coronal [Fe X] λ6375 and [Fe XIV] λ5303 lines at detection limits near an equivalent width of 1 mÅ in the best cases. In general agreement with predictions based on a multi-phase model of the interstellar medium, no absorption which can be attributed to Fe X or Fe XIV ions in hot interstellar gas emitting the soft x-ray background is seen in any of these spectra, except for two. Toward λ Cephei an absorption line near λ6375 is measured with an equivalent width of 8.1 ± 2 mÅ, a width corresponding to 20 ± 5 km s-1 or a temperature T ≤ (0.5 ± 0.25) x 106 °K, and, if it is caused by Fe X ions, a radial velocity of -355 km s-1. On that hypothesis, the hot interstellar gas constitutes at least 63% of the column density of gas along this light path.

scholarly journals Quantitative spectral classification of Galactic O stars

2018 ◽  
Vol 616 ◽  
pp. A135 ◽  
Author(s):  
F. Martins
Keyword(s):  
Spectral Range ◽  
Spectral Resolution ◽  
Equivalent Width ◽  
Classification Criteria ◽  
High Spectral Resolution ◽  
Spectral Classification ◽  
Class V ◽  
Luminosity Class ◽  
Spectral Class

Our goal is to provide a quantification of several spectral classification criteria for O stars. We collect high-spectral resolution spectra of 105 Galactic O-type stars from various archives. We measured equivalent widths of classification lines. We defined average values of classification criteria for given spectral types and luminosity classes. We find that the ratio He I 4471 to He II 4542 well matches the published ratios for spectral types. We have quantified equivalent width ratios of helium and silicon lines among O8–O9.7 stars to refine spectral class typing in this spectral range. We present quantitative criteria to separate between luminosity class V, IV–III–II (grouped), and I among O3–O8.5 stars, mainly based on the strength of He II 4686. We find that these criteria also define very well the f, (f), and ((f)) classes for O3–O7.5 stars. Among O9–O9.7 stars we quantify the ratios of He II 4686 to He I 4713 and Si IV 4089 to He I 4026 for all luminosity classes. The tabulated values of the classification criteria should help classify any new O-type stars. The final step of the classification process should rely on a direct comparison to standard stars of the assigned spectral type or luminosity class.

Turbulent boundary-layer flow on a rotating disk

1969 ◽  
Vol 37 (1) ◽  
pp. 129-147 ◽  
Author(s):  
T-S. Cham ◽  
M. R. Head
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Rotating Disk ◽  
Circumferential Velocity ◽  
Auxiliary Equation ◽  
Two Dimensional ◽  
Free Air ◽  
Radial Profiles ◽  
Layer Flow ◽  
Momentum Integral

Calculations have been made of the development of the turbulent boundary layer on a disk rotating in free air, using circumferential and radial momentum-integral equations and an auxiliary equation of entrainment. In the calculations, circumferential velocity profiles are represented by Thompson's (1965) two-parameter family, while radial profiles are given by Mager's (1952) quadratic expression. The circumferential component of skin friction follows from the use of Thompson's profile family for the circumferential velocity. The entrainment, in dimensionless form, is assumed to be determined uniquely by the circumferential velocity profile in the same way as was proposed by Head (1958) for a two-dimensional turbulent boundary layer.Detailed measurements have been made of the development of the turbulent boundary layer on the rotating disk, and the calculations are found to be in excellent agreement with the results when a suitable adjustment is made to Head's two-dimensional entrainment curve.

scholarly journals The Evolution of Moderately Ionized Gas in the Universe

2006 ◽  
Vol 2 (S235) ◽  
pp. 416-416
Author(s):  
Eric Monier ◽  
Dan Nestor ◽  
Sandhya Rao ◽  
David Turnshek ◽  
Michael Daino ◽  
...  
Keyword(s):  
Absorption Line ◽  
Ionized Gas ◽  
The Universe

AbstractWe present results on the properties and evolution of moderately ionized gas in the Universe based on intervening CIV absorption-line systems. We have compiled a database of CIV systems from the SDSS, and we find evidence for evolution in the incidence of CIV absorbers.

Comparison of Free Spectral Range and Quality Factor for Two-Dimensional Square and Circular Microcavities

2004 ◽  
Vol 21 (1) ◽  
pp. 79-80 ◽  
Author(s):  
Guo Wei-Hua ◽  
Huang Yong-Zhen ◽  
Lu Qiao-Yin ◽  
Yu Li-Juan
Keyword(s):  
Quality Factor ◽  
Spectral Range ◽  
Free Spectral Range ◽  
Two Dimensional
Sign in / Sign up

Export Citation Format

Share Document