scholarly journals High Resolution CO Imaging of a Cometary Globule in the Helix Nebula

2003 ◽  
Vol 209 ◽  
pp. 277-278
Author(s):  
P. J. Huggins ◽  
T. Forveille ◽  
R. Bachiller ◽  
P. Cox
Keyword(s):  
High Resolution ◽  
Neutral Gas ◽  
Line Imaging

We report high resolution CO (1–0) line imaging of a prominent cometary globule in the Helix Nebula. The results confirm earlier observations (Huggins et al. 1992) that globules consist of dense condensations of neutral gas embedded in the ionized nebula, and they provide new constraints on the structure and kinematics of the gas.

scholarly journals Recommended isolated-line profile for representing high-resolution spectroscopic transitions (IUPAC Technical Report)

2014 ◽  
Vol 86 (12) ◽  
pp. 1931-1943 ◽  
Author(s):  
Jonathan Tennyson ◽  
Peter F. Bernath ◽  
Alain Campargue ◽  
Attila G. Császár ◽  
Ludovic Daumont ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
Pressure Effects ◽  
Task Group ◽  
High Resolution Spectroscopy ◽  
Line Shapes ◽  
Neutral Gas ◽  
Voigt Profile ◽  
Simplifying Assumptions ◽  
On Line

Abstract The report of an IUPAC Task Group, formed in 2011 on “Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory” (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule have resulted in the development of a variety of alternative line-profile models. These models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity. The Task Group recommends that the partially Correlated quadratic-Speed-Dependent Hard-Collision profile (pCqSD-HCP) should be adopted as the appropriate model for high-resolution spectroscopy. For simplicity this should be called the Hartmann–Tran profile (HTP). The HTP is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the Voigt profile, under certain simplifying assumptions.

The Line of Sight of ϵ Canis Majoris: Depletion and Extent of the Local Cloud

1997 ◽  
Vol 166 ◽  
pp. 161-164
Author(s):  
Cécile Gry ◽  
Olivier Dupin
Keyword(s):  
High Resolution ◽  
Column Density ◽  
Uv Spectra ◽  
Line Of Sight ◽  
Gas Density ◽  
Neutral Gas ◽  
Local Cloud

AbstractWith new high resolution UV spectra of ϵ CMa we show that the gas column density in this sight-line is less than 4 1017 cm−2, that the neutral gas density is less than 10−5 cm−3 after the first 3 parsecs, and that the Local Cloud seems to be almost undepleted and to extend to no more than 0.6 pc in this direction.

scholarly journals Low-mass star formation in bright rimmed clouds

2007 ◽  
Vol 3 (S242) ◽  
pp. 164-165
Author(s):  
V. Migenes ◽  
M. A. Trinidad ◽  
R. Valdettaro ◽  
F. Palla ◽  
J. Brand
Keyword(s):  
Boundary Layer ◽  
Star Formation ◽  
High Resolution ◽  
Shock Front ◽  
Detection Rate ◽  
Mass Star ◽  
Neutral Gas ◽  
Evolutionary Phase ◽  
Low Mass ◽  
External Ionization

AbstractBright Rimmed Clouds (BRCs) are clouds that have been compressed by an external ionization-shock front which focuses the neutral gas into compact globules. The boundary layer between the neutral gas and the gas ionized by the incident photons is often called “bright rim” but the clumps are sometimes classified also as speck globules or cometary globules depending on their appearance. Small globules with bright rims have been considered to be potential sites of star formation and have been studied in several individual regions. We present the first high resolution VLA observations of 20 of these BRCs, but only three detections were obtained. The low detection rate seems to support the idea that BRCs produce mostly low-luminosity objects, for which maser emission is weak and episodic, and that the embedded sources are in a more advanced evolutionary phase than class 0 objects.

scholarly journals Assessing mesoscale material response under shock & isentropic compression via high-resolution line-imaging VISAR.

2003 ◽  
Author(s):  
Clint Allen Hall ◽  
Michael David Furnish ◽  
Jason W. Podsednik ◽  
William Dodd Reinhart ◽  
Wayne Merle Trott ◽  
...  
Keyword(s):  
High Resolution ◽  
Isentropic Compression ◽  
Material Response ◽  
Line Imaging

High-Resolution CO and H[TINF]2[/TINF] Molecular Line Imaging of a Cometary Globule in the Helix Nebula

2002 ◽  
Vol 573 (1) ◽  
pp. L55-L58 ◽  
Author(s):  
P. J. Huggins ◽  
T. Forveille ◽  
R. Bachiller ◽  
P. Cox ◽  
N. Ageorges ◽  
...  
Keyword(s):  
High Resolution ◽  
Molecular Line ◽  
Line Imaging

scholarly journals Asymmetric drift of Andromeda analogues in the IllustrisTNG simulation

2020 ◽  
Vol 497 (3) ◽  
pp. 2870-2882
Author(s):  
Amanda C N Quirk ◽  
Ekta Patel
Keyword(s):  
High Resolution ◽  
Rotation Curve ◽  
Age Groups ◽  
Time Frame ◽  
Centre Of Mass ◽  
Stellar Rotation ◽  
Internal Heating ◽  
Rotation Curves ◽  
Neutral Gas ◽  
Andromeda Galaxy

ABSTRACT We analyse the kinematics as a function of stellar age for Andromeda (M31) mass analogues from the IllustrisTNG cosmological simulation. We divide the star particles into four age groups: <1, 1–5, 5–10, and >10 Gyr, and compare the kinematics of these groups to that of the neutral gas cells. We calculate rotation curves for the stellar and gaseous components of each analogue from 2 to 20 kpc from the centre of mass. We find that the lag, or asymmetric drift (AD), between the gas rotation curve and the stellar rotation curve on average increases with stellar age. This finding is consistent with observational measurements of AD in the disc of the Andromeda galaxy. When the M31 analogues are separated into groups based on merger history, we find that there is a difference in the AD of the analogues that have had a 4:1 merger the last 4, 8, or 12 Gyr compared to analogues that have not experienced a 4:1 merger in the same time frame. The subset of analogues that have had a 4:1 merger within the last 4 Gyr are also similar to AD measurements of stars in M31’s disc, providing evidence that M31 may in fact have recently merged with a galaxy nearly one-fourth of its mass. Further work using high-resolution zoom-in simulations is required to explore the contribution of internal heating to AD.

High Resolution & High Sensitivity Spectral-Line Imaging with Multiple Arrays

1994 ◽  
pp. 334-336
Author(s):  
V. Migenes ◽  
J. A. Yates ◽  
R. J. Cohen ◽  
M. C. Shepherd ◽  
P. F. Bowers
Keyword(s):  
High Resolution ◽  
Spectral Line ◽  
High Sensitivity ◽  
Line Imaging

scholarly journals High Resolution & High Sensitivity Spectral-Line Imaging with Multiple Arrays

1994 ◽  
Vol 158 ◽  
pp. 334-336
Author(s):  
V. Migenes ◽  
J.A. Yates ◽  
R.J. Cohen ◽  
M.C. Shepherd ◽  
P.F. Bowers
Keyword(s):  
High Resolution ◽  
Spectral Line ◽  
Spectral Resolution ◽  
High Sensitivity ◽  
Large Array ◽  
Very Large Array ◽  
Line Imaging ◽  
Line Work ◽  
Low Sensitivity ◽  
The Uk

At present there are several radio interferometer arrays ranging from the low-resolution (0.1–1″) high-sensitivity arrays such as the Very Large Array (VLA) to the high-resolution (0.0005–0.1″) low-sensitivity arrays such as MERLIN (though MERLIN, in the UK, is really in between this broad category), EVN, VLBA and SHEVE. Combining high sensitvity and high resolution is prohibitively expensive, because to have the u–v sampling of small arrays would require more and larger antenna elements. Hence high- resolution arrays have poor u–v coverage, decreasing the sensitivity of the instrument. This has a serious effect on spectral-line work, where sensitivity has already been sacrificed in the pursuit of spectral resolution.

Emission-Line Imaging of QSO[CLC]s[/CLC] with High Resolution

2001 ◽  
Vol 121 (1) ◽  
pp. 80-89 ◽  
Author(s):  
J. B. Hutchings ◽  
S. L. Morris ◽  
D. Crampton
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Line Imaging
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