scholarly journals Physical conditions and chemical abundances in PN M 2-36. Results from deep echelle observations

2021 ◽  
Author(s):  
José N Espíritu ◽  
Antonio Peimbert
Keyword(s):  
Chemical Structure ◽  
Ultra Violet ◽  
Emission Lines ◽  
High Spectral Resolution ◽  
Large Telescope ◽  
Echelle Spectrograph ◽  
Chemical Abundances ◽  
Physical Conditions ◽  
Very Large Telescope ◽  
Physical And Chemical

Abstract We present a spectrum of the planetary nebula M 2-36 obtained using the Ultra Violet and Visual Echelle Spectrograph (UVES) at the Very Large Telescope (VLT). 446 emission lines are detected. We perform an analysis of the chemical composition using multiple electron temperature (Te) and density (ne) diagnostics. Te and ne are computed using a variety of methods, including collisionally excited line (CEL) ratios, O++ optical recombination lines (ORLs), and measuring the intensity of the Balmer jump. Besides the classical CEL abundances, we also present robust ionic abundances from ORLs of heavy elements. From CELs and ORLs of O++, we obtain a new value for the Abundance Discrepancy Factor (ADF) of this nebula, being ADF(O++) = 6.76 ± 0.50. From all the different line ratios that we study, we find that the object cannot be chemically homogeneous; moreover, we find that two-phased photoionization models are unable to simultaneously reproduce critical ${\rm O\, \small {II}}$ and [${\rm O\, \small {III}}$] line ratios. However, we find a three-phased model able to adequately reproduce such ratios. While we consider this to be a toy model, it is able to reproduce the observed temperature and density line diagnostics. Our analysis shows that it is important to study high ADF PNe with high spectral resolution, since its physical and chemical structure may be more complicated than previously thought.

scholarly journals Exoplanet atmospheres at high spectral resolution: A CRIRES survey of hot-Jupiters

2010 ◽  
Vol 6 (S276) ◽  
pp. 208-211
Author(s):  
Ignas Snellen ◽  
Remco de Kok ◽  
Ernst de Mooij ◽  
Matteo Brogi ◽  
Bas Nefs ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Mass Composition ◽  
Large Telescope ◽  
Test Bed ◽  
Echelle Spectrograph ◽  
Hot Jupiters ◽  
Transiting Planets ◽  
Very Large Telescope

AbstractRecently, we presented the detection of carbon monoxide in the transmission spectrum of extrasolar planet HD209458b, using CRIRES, the Cryogenic high-resolution Infrared Echelle Spectrograph at ESO's Very Large Telescope (VLT). The high spectral resolution observations (R=100,000) provide a wealth of information on the planet's orbit, mass, composition, and even on its atmospheric dynamics. The new observational strategy and data analysis techniques open up a whole world of opportunities. We therefore started an ESO large program using CRIRES to explore these, targeting both transiting and non-transiting planets in carbon monoxide, water vapour, and methane. Observations of the latter molecule will also serve as a test-bed for METIS, the proposed mid-infrared imager and spectrograph for the European Extremely Large Telescope.

scholarly journals First detection of the O III 495.8911 and 500.6843 nm lines in the Earth's upper atmosphere

2011 ◽  
Vol 29 (12) ◽  
pp. 2235-2238 ◽  
Author(s):  
O. Witasse ◽  
T. Slanger ◽  
R. Thissen
Keyword(s):  
Atomic Oxygen ◽  
The State ◽  
Upper Atmosphere ◽  
Emission Lines ◽  
Large Telescope ◽  
Echelle Spectrograph ◽  
Very Large Telescope ◽  
Doubly Charged

Abstract. We report the first detection of two emission lines of the atomic oxygen doubly-charged ion at 495.8911 and 500.6843 nm in the terrestrial upper atmosphere. They correspond to the transitions 1D2-3P1 and 1D2-3P2 of the O++ ion, respectively. The measurements were performed on 30 October 2003 during the "Halloween" storms, with the Ultraviolet and Visual Echelle Spectrograph (UVES) mounted on the Very Large Telescope (VLT) in Chile. The intensities of these emissions are ~70 mRayleigh, and ~260 mRayleigh, respectively. These emissions constitute a new diagnostic of the state of the ionosphere.

scholarly journals Twenty years of observations of PM 1-188: Its chemical abundances and extraordinary kinematics

2021 ◽  
Author(s):  
Miriam Peña ◽  
Liliana Hernández-Martínez ◽  
Francisco Ruiz-Escobedo
Keyword(s):  
Chemical Composition ◽  
Planetary Nebula ◽  
Central Star ◽  
Emission Lines ◽  
Type I ◽  
Chemical Abundances ◽  
Line Intensities ◽  
Physical Conditions ◽  
The Past ◽  
Spectrophotometric Data

Abstract The analysis of 20 years of spectrophotometric data of the double shell planetary nebula PM 1-188 is presented, aiming to determine the time evolution of the emission lines and the physical conditions of the nebula, as a consequence of the systematic fading of its [WC 10] central star whose brightness has declined by about 10 mag in the past 40 years. Our main results include that the [O iii], [O ii], [N ii] line intensities are increasing with time in the inner nebula as a consequence of an increase in electron temperature from 11 000 K in 2005 to more than 14 000 K in 2018, due to shocks. The intensity of the same lines are decreasing in the outer nebula, due to a decrease in temperature, from 13 000 K to 7000 K, in the same period. The chemical composition of the inner and outer shells was derived and they are similar. Both nebulae present subsolar O, S and Ar abundances, while they are He, N and Ne rich. For the outer nebula the values are 12+log He/H = 11.13 ± 0.05, 12+log O/H = 8.04 ± 0.04, 12+log N/H = 7.87 ± 0.06, 12+log S/H = 7.18 ± 0.10 and 12+log Ar = 5.33 ± 0.16. The O, S and Ar abundances are several times lower than the average values found in disc non-Type I PNe, and are reminiscent of some halo PNe. From high resolution spectra, an outflow in the N-S direction was found in the inner zone. Position-velocity diagrams show that the outflow expands at velocities in the −150 to 100 km s−1 range, and both shells have expansion velocities of about 40 km s−1.

scholarly journals The impact of spectra quality on nebular abundances

2020 ◽  
Vol 495 (1) ◽  
pp. 1016-1034 ◽  
Author(s):  
Mónica Rodríguez
Keyword(s):  
Planetary Nebulae ◽  
The Other ◽  
Statistical Equilibrium ◽  
Emission Lines ◽  
Reference Spectrum ◽  
Equilibrium Equations ◽  
Chemical Abundances ◽  
Physical Conditions ◽  
Observational Errors ◽  
The Impact

ABSTRACT I explore the effects of observational errors on nebular chemical abundances using a sample of 179 optical spectra of 42 planetary nebulae (PNe) observed by different authors. The spectra are analysed in a homogeneous way to derive physical conditions and ionic and total abundances. The effects of recombination on the [O ii] and [N ii] emission lines are estimated by including the effective recombination coefficients in the statistical equilibrium equations that are solved for O+ and N+. The results are shown to be significantly different than those derived using previous approaches. The O+ abundances derived with the blue and red lines of [O ii] differ by up to a factor of 6, indicating that the relative intensities of lines widely separated in wavelength can be highly uncertain. In fact, the He ii lines in the range 4000–6800 Å imply that most of the spectra are bluer than expected. Scores are assigned to the spectra using different criteria and the spectrum with the highest score for each PN is taken as the reference spectrum. The differences between the abundances derived with the reference spectrum and those derived with the other spectra available for each object are used to estimate the 1σ observational uncertainties in the final abundances: 0.11 dex for O/H and Ar/H, 0.14 dex for N/H, Ne/H, and Cl/H, and 0.16 dex for S/H.

scholarly journals The full infrared spectrum of molecular hydrogen

2019 ◽  
Vol 630 ◽  
pp. A58 ◽  
Author(s):  
E. Roueff ◽  
H. Abgrall ◽  
P. Czachorowski ◽  
K. Pachucki ◽  
M. Puchalski ◽  
...  
Keyword(s):  
Infrared Spectrum ◽  
Magnetic Dipole ◽  
Molecular Hydrogen ◽  
Radiative Lifetime ◽  
Electric Quadrupole ◽  
Molecular State ◽  
High Spectral Resolution ◽  
Echelle Spectrograph ◽  
Very Large Telescope ◽  
Magnetic Dipole Transitions

Context. The high spectral resolution R ∼ 45 000 provided by IGRINS (Immersion Grating INfrared Spectrometer) at MacDonald Observatory and R ∼ 100 000 achieved by CRIRES (CRyogenic high-resolution InfraRed Echelle Spectrograph) at VLT (Very Large Telescope) challenges the present knowledge of infrared spectra. Aims. We aim to predict the full infrared spectrum of molecular hydrogen at a comparable accuracy. Methods. We take advantage of the recent theoretical ab initio studies on molecular hydrogen to compute both the electric quadrupole and magnetic dipole transitions taking place within the ground electronic molecular state of hydrogen. Results. We computed the full infrared spectrum of molecular hydrogen at an unprecedented accuracy and derive for the first time the emission probabilities including both electric quadrupole (ΔJ = 0, ±2) and magnetic dipole transitions (ΔJ = 0) as well as the total radiative lifetime of each rovibrational state. Inclusion of magnetic dipole transitions increases the emission probabilities by factors of a few for highly excited rotational levels, which occur in the 3–20 μ range.

scholarly journals The Physical and Chemical Structure of Warm, Dense Regions: IC 63 and IC 443

1992 ◽  
Vol 150 ◽  
pp. 319-320
Author(s):  
D.J. Jansen ◽  
E.F. Van Dishoeck ◽  
J.H. Black ◽  
T.G. Phillips
Keyword(s):  
Shock Waves ◽  
Molecular Clouds ◽  
Chemical Structure ◽  
Elevated Temperatures ◽  
Chemical Abundances ◽  
Molecular Line ◽  
External Galaxies ◽  
Ultraviolet Photons ◽  
Physical And Chemical ◽  
Initial Results

Elevated temperatures in molecular clouds can result either from heating by ultraviolet photons or from the passage of shock waves. The effect that these processes have on the chemical abundances is not well established observationally, but is of great importance for the interpretation of molecular line observations not only in our own Galaxy, but also in external galaxies. We present here initial results from our study of two “template” regions: the photon-dominated region IC 63 and the shocked region IC 443.

scholarly journals Nebula around R Corona Borealis

2011 ◽  
Vol 7 (S283) ◽  
pp. 476-477 ◽  
Author(s):  
N. Kameswara Rao ◽  
David L. Lambert
Keyword(s):  
Electron Density ◽  
Spectral Resolution ◽  
General Characteristic ◽  
Emission Lines ◽  
High Spectral Resolution ◽  
Low Density ◽  
Deep Minimum ◽  
Physical Conditions ◽  
Double Peaks ◽  
R Coronae Borealis Stars

AbstractThe star R Corona Borealis (R CrB) shows forbidden lines of [O II], [N II], and [S II] during the deep minimum when the star is fainter by about 8 to 9 magnitudes from normal brightness, suggesting the presence of nebular material around it. We present low and high spectral resolution observations of these lines during the ongoing deep minimum of R CrB, which started in July 2007. These emission lines show double peaks with a separation of about 170 km/s. The line ratios of [S II] and [O II] suggest an electron density of about 100 cm−3. We discuss the physical conditions and possible origins of this low density gas. These forbidden lines have also been seen in other R Coronae Borealis stars during their deep light minima and this is a general characteristic of these stars, which might have some relevance to their origins.

scholarly journals Uses of Very Large Telescopes for Galaxy Research

1984 ◽  
Vol 79 ◽  
pp. 703-711 ◽  
Author(s):  
M.-H. Ulrich
Keyword(s):  
Elliptical Galaxies ◽  
Point Sources ◽  
High Spectral Resolution ◽  
Large Field ◽  
Large Telescope ◽  
Quasar Spectra ◽  
Very Large Telescope ◽  
Large Telescopes ◽  
Field Imaging

SummaryMany areas of extragalactic research will greatly benefit from observations with a very large telescope. We concentrate, here, on four of them as illustrative examples:First we briefly discuss the study of the absorption lines in quasar spectra.In the second section we suggest the possibility of doing serendipity large field imaging during high spectral resolution exposures on point sources.In sections 3 and 4 we discuss two topics which have long been recognized as important drivers for the construction of very large telescopes, the determination of the nature of the missing mass, and the study of elliptical galaxies.

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