scholarly journals High Accuracy Molecular Line Lists for Studies of Exoplanets and Other Hot Atmospheres

2022 ◽  
Vol 8 ◽  
Author(s):  
Jonathan Tennyson ◽  
Sergey N. Yurchenko
Keyword(s):  
Spectroscopic Data ◽  
Extrasolar Planets ◽  
Current Status ◽  
Laboratory Studies ◽  
Molecular Line ◽  
The Earth ◽  
Cool Stars ◽  
Competing Demands ◽  
Spectroscopic Information ◽  
The Many

The desire to characterize and model the atmospheres of the many extrasolar planets that have been discovered over the last three decades is a major driver of current astronomy. However, this goal is impacted by the lack of spectroscopic data on the molecules in question. As most atmospheres that can be studied are hot, some surprisingly so, this activity requires spectroscopic information not readily available from laboratory studies. This article will review the current status of available molecular spectroscopic data, usually presented as line lists, for studies of exoplanet atmospheres and, indeed, the atmospheres of other astronomical objects hotter than the Earth such as brown dwarfs, cool stars and even sunspots. Analysis of exoplanet transit spectra and the calculation of the relevant opacities often require huge datasets comprising billions of individual spectroscopic transitions. Conversely, the newly-developed high-resolution Doppler-shift spectroscopy technique has proved to be a powerful tool for detecting molecular species in exoplanet atmospheres, but relies on the use of smaller, highly accurate line lists. Methods of resolving issues arising from the competing demands of completeness versus accuracy for line lists are discussed.

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

scholarly journals On particle acceleration and transport in plasmas in the Galaxy: theory and observations

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
Elena Amato ◽  
Sabrina Casanova
Keyword(s):  
Particle Acceleration ◽  
Cosmic Rays ◽  
Galactic Cosmic Rays ◽  
Energetic Particles ◽  
Quality Data ◽  
Current Status ◽  
The Earth ◽  
The Galaxy ◽  
Formation And Evolution ◽  
Galaxy Assembly

Accelerated particles are ubiquitous in the Cosmos and play a fundamental role in many processes governing the evolution of the Universe at all scales, from the sub-AU scale relevant for the formation and evolution of stars and planets to the Mpc scale involved in Galaxy assembly. We reveal the presence of energetic particles in many classes of astrophysical sources thanks to their production of non-thermal radiation, and we detect them directly at the Earth as cosmic rays. In the last two decades both direct and indirect observations have provided us a wealth of new, high-quality data about cosmic rays and their interactions both in sources and during propagation, in the Galaxy and in the Solar System. Some of the new data have confirmed existing theories about particle acceleration and propagation and their interplay with the environment in which they occur. Some others have brought about interesting surprises, whose interpretation is not straightforward within the standard framework and may require a change of paradigm in terms of our ideas about the origin of cosmic rays of different species or in different energy ranges. In this article, we focus on cosmic rays of galactic origin, namely with energies below a few petaelectronvolts, where a steepening is observed in the spectrum of energetic particles detected at the Earth. We review the recent observational findings and the current status of the theory about the origin and propagation of galactic cosmic rays.

scholarly journals Cassini/Huygens Mission To Saturn: Results And Prospects

2005 ◽  
Vol 13 ◽  
pp. 904-904
Author(s):  
Dennis L. Matson ◽  
Jean-Pierre Lebreton ◽  
Linda Spilker
Keyword(s):  
Magnetic Field ◽  
Current Status ◽  
Outer Planet ◽  
Simultaneous Measurements ◽  
The Earth ◽  
Bilateral Agreement ◽  
Interplanetary Trajectory ◽  
Jovian System ◽  
Intensive Observations ◽  
Scientific Results

The Cassini spacecraft was launched in October, 1997. Since then it has been on an interplanetary trajectory aimed toward Saturn and arriving there on July 1, 2004. En route, Cassini has flown by Venus, the Earth, and Jupiter. Each of these events yielded new scientific results, (e.g., 11 papers in J. Geophys. Res. 106, 30099-30279.) The Cassini flyby of Jupiter, with Galileo already in Jovian orbit, enabled the first-ever simultaneous measurements by two spacecraft at an outer planet. This fortuitous event provided a unique opportunity to investigate the giant planet’s magnetic field and the properties of the Jovian system. It provided a focused period for intensive observations of Jupiter and cooperation with investigators using Galileo, Hubble, Chandra, and ground-based observatories. The results achieved at Jupiter were stunning (e.g., 8 articles in Nature 415, 965-1005, February 28, 2002). Recent results and the current status of the spacecraft and mission will be discussed. Of note are the dates of July 1, 2004 when Cassini goes into orbit about Saturn and January 14, 2005 when Huygens enters the atmosphere of Titan. The Cassini/Huygens mission is a joint undertaking by NASA and ESA, with ASI as a partner via a bilateral agreement with NASA.

scholarly journals L’hypermédia Au Service De La Formation Initiale D’enseignants-Stagiaires (Cas Du CRMEF-FESMEKNES)

2017 ◽  
Vol 13 (16) ◽  
pp. 113
Author(s):  
Youssef Nafidi ◽  
Anouar Alami ◽  
Moncef Zaki ◽  
Hanane Afkar ◽  
Mohammed Elazami Elhassani
Keyword(s):  
New Technologies ◽  
Initial Training ◽  
Formation Initiale ◽  
Trainee Teachers ◽  
Digital Resource ◽  
The Earth ◽  
Information And Communication ◽  
Promising Solution ◽  
The Many ◽  
And Training

In light of empirical experience from Morocco, combined with new possibilities afforded by Information and Communication Technology (ICT), there is a wish to integrate new technologies into distance education to help solve a set of problems identified in the initial training at the Regional Centre for the Professions of Education and Training of Fez-Meknes. The results of a study conducted among 15 trainee teachers of the Earth and Life Sciences allow us to conclude that designing a hypermedia tool for learning could constitute a promising solution to address the many challenges linked to the initial training of teachers in Morocco. Finally, the use of this digital resource by trainee teachers’ has also strongly contributed to their eagerness to integrate ICT in their subsequent teaching practices.

scholarly journals The Marketing of Canadian University Rankings: A Misadventure Now 24 Years Old

2016 ◽  
Vol 9 ◽  
pp. 227
Author(s):  
Ken Cramer ◽  
Stewart Page ◽  
Vanessa Burrows ◽  
Chastine Lamoureux ◽  
Sarah Mackay ◽  
...  
Keyword(s):  
Current Status ◽  
Annual Data ◽  
University Rankings ◽  
Negative Consequences ◽  
Ranking Data ◽  
Canadian Universities ◽  
Cluster Analyses ◽  
Student Welfare ◽  
The Many ◽  
Personal Welfare

Based on analyses of Maclean’s ranking data pertaining to Canadian universities published over the last 24 years, we present a summary of statistical findings of annual ranking exercises, as well as discussion about their current status and the effects upon student welfare. Some illustrative tables are also presented. Using correlational and cluster analyses, for each year, we have found largely nonsignificant, inconsistent, and uninterpretable relations between rank standings of universities and Maclean’s main measures, as well as between rank standings and the many specific indices used to generate these standings. In our opinion, when assessed in terms of their empirical characteristics, the annual data show generally that this system of ranking is highly limited in terms of its practical or academic value to students. Among other difficulties with the interpretation of ranks, we also discuss the possibility that ranking exercises have unintended, though potentially serious, negative consequences for the intellectual and personal welfare of students.

Thermal consequences of impact bombardments to silicate crusts of terrestrial-type exoplanets

2021 ◽  
Author(s):  
Stephen J. Mojzsis ◽  
Oleg Abramov
Keyword(s):  
Extrasolar Planets ◽  
Unit Area ◽  
Production Functions ◽  
Asteroid Belt ◽  
Earth Planet ◽  
Cross Sectional ◽  
The Earth ◽  
Main Asteroid Belt ◽  
Gravitational Compression ◽  
Impactor Velocity

<p><strong>Introduction. </strong>Post-accretionary impact bombardment is part of planet formation and leads to localized, regional [e.g., 1-3], or even wholesale global melting of silicate crust [e.g., 4]; less intense bombardment can also create hydrothermal oases favorable for life [e.g, 5]. Here, we generalize the effects of late accretion bombardments to extrasolar planets of different masses (0.1-10M<sub>⊕</sub>). One example is Proxima Centauri b, estimated at ~2× M<sub>⊕</sub> [6]. We model a 0.1M<sub>⊕ </sub>“mini-Earth”<sub></sub>and “super-Earth” at 10M<sub>⊕</sub>, the approximate upper limit for a “mini-Neptune” [7]. Output predicts lithospheric melting and subsurface habitable volumes.</p><p><strong>Methods. </strong>The model [1,2] consists of (i) stochastic cratering; (ii) analytical thermal expressions for each crater [e.g., 8,9]; and (iii) a 3-D thermal model of the lithosphere, where craters cool by conduction and radiation.</p><p>We analyze impact bombardments using our solar system’s mass production functions for the first 500 Myr [10]. Surface temperatures and geothermal gradients are set to 20 °C and 70 °C/km [2]. Total delivered mass for Earth is 7.8 × 10<sup>21</sup> kg, and scaled to other planets based on cross-sectional areas, with 1.7 × 10<sup>21</sup> kg for mini-Earth, 1.2 × 10<sup>22</sup> kg for Proxima Centauri b, and 3.6 × 10<sup>22</sup> kg for super-Earth. The impactors' SFD is based on our main asteroid belt [11]. Impactor and target densities are set to 3000 kg m<sup>-3</sup> and planetary bulk densities are assumed to be 5510 kg m<sup>-3</sup>, omitting gravitational compression [7]. Impactor velocity was estimated at 1.5 × v<sub>esc</sub> for each planet, with 7.8 km s<sup>-1</sup> for mini-Earth,  16.8 km s<sup>-1</sup> for the Earth, 21.1 km s<sup>-1</sup> for Proxima Centauri b, and 36.1 km s<sup>-1</sup> for super-Earth.</p><p><strong>Results. </strong>We assume fully formed crusts, so melt volume immediately increases due to impacts. Super-Earth reaches a maximum of ~45% of the lithosphere in molten state, whereas mini-Earth reaches a maximum of only ~5%.  This is due to much higher impact velocities and cratering densities on the super-Earth compared to mini-Earth. We also show the geophysical habitable volumes within the upper 4 km of a planet’s crust as the bombardment progresses. Impacts sterilize the majority of the habitable volume on super-Earth; however, due to its large total volume, the total habitable volume is still higher than on other planets despite the more intense bombardment in terms of energy delivered per unit area.</p><p><strong>References:</strong> [1] Abramov, O., and S.J. Mojzsis (2009) Nature, 459, 419-422. [2] Abramov et al. (2013) Chemie der Erde, 73, 227-248. [3] Abramov, O., and S. J. Mojzsis (2016) Earth Planet Sci. Lett., 442, 108-120. [4] Canup, R. M. (2004) Icarus, 168, 433-456. [5] Abramov, O., and D. A. Kring (2004) J. Geophys. Res., 109(E10). [6] Tasker, E. J. et al. (2020). Astronom. J., 159(2), 41. [7] Marcy, G. W. et al. (2014). PNAS, 111(35), 12655-12660. [8] Kieffer S. W. and Simonds C. H. (1980) Rev. Geophys. Space Phys., 18, 143-181. [9] Pierazzo E., and H.J. Melosh (2000). Icarus, 145, 252-261. [10] Mojzsis, S. J. et al. (2019). Astrophys. J., 881(1), 44. [11] Bottke, W. F. et al. (2010) Science, 330, 1527-1530.</p>

Current status of heart transplantation

2018 ◽  
pp. 223-240
Author(s):  
Ayyaz Ali ◽  
Robert L. Kormos
Keyword(s):  
Heart Transplantation ◽  
Cardiac Transplantation ◽  
Organ Procurement ◽  
Severe Heart Failure ◽  
Surgical Techniques ◽  
Current Status ◽  
Definitive Treatment ◽  
Term Survival ◽  
The Many ◽  
End Stage

Cardiac transplantation has extended and improved the lives of patients suffering from severe heart failure over many decades. Despite advances in medical therapy, cardiac transplantation remains the definitive treatment for end-stage heart disease. Surgical techniques for organ procurement and implantation, development of appropriate methods for preserving the heart, and understanding the immunological challenges associated with transplantation were among the many areas which required focused investigation. In the current era, heart transplantation is associated with a low operative mortality and excellent long-term survival, however, the major obstacle of shortage of suitable donor organs remains. In the following chapter, recipient selection and management, donor organ procurement and preservation, and surgical techniques of heart transplantation are described in detail.

scholarly journals Role of Piezoelectric Elements in Finding the Mechanical Properties of Solid Industrial Materials

2018 ◽  
Vol 8 (10) ◽  
pp. 1737 ◽  
Author(s):  
Arshed Mohammed ◽  
Sallehuddin Haris ◽  
Mohd Nuawi
Keyword(s):  
Mechanical Properties ◽  
State Of The Art ◽  
New Technology ◽  
Material Testing ◽  
Current Status ◽  
Piezoelectric Elements ◽  
Need To Evaluate ◽  
Recent Developments ◽  
The Many

Recent developments in ultrasonic material testing have increased the need to evaluate the current status of the different applications of piezoelectric elements (PEs). This research have reviewed state-of-the-art emerging new technology and the role of PEs in tests for a number of mechanical properties, such as creep, fracture toughness, hardness, and impact toughness, among others. In this field, importance is given to the following variables, namely, (a) values of the natural frequency to PEs, (b) type and dimensions of specimens, and (c) purpose of the tests. All these variables are listed in three tables to illustrate the nature of their differences in these kinds of tests. Furthermore, recent achievements in this field are emphasized in addition to the many important studies that highlight the role of PEs.

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