Lithium abundance is a gravitational model dependent quantity

AbstractWe computed the impact solutions of the potentially dangerous Near Earth Asteroid (NEA) 2001 BB16 based on 47 optical observations from January 20.08316 UTC, 2001, through February 09.15740 UTC, 2016, and one radar observation from January 19.90347 UTC, 2016. We used two methods to sample the starting Line of Variation (LOV). First method, called thereafter LOV1, with the uniform sampling of the LOV parameter, out to LOV = 5 computing 3000 virtual asteroids (VAs) on both sides of the LOV, which gives 6001 VAs and propagated their orbits to JD2525000.5 TDT=February 12, 2201. We computed the non-gravitational parameterA2=(34.55±7.38)·10–14 au/d2 for nominal orbit of 2001 BB16 and possible impacts with the Earth until 2201. For potential impact in 2195 we find A2=20.0·10−14 au/d2. With a positive value of A2, 2001 BB16 can be prograde rotator. Moreover, we computed Lyapunov Time (LT) for 2001 BB16, which for all VAs, has a mean value of about 25 y. We showed that impact solutions, including the calculated probability of a possible collision of a 2001 BB16 asteroid with the Earth depends on how to calculate and take into account the appropriate gravitational model, including the number of perturbing massive asteroids. In some complicated cases, it may depend also on the number of clones calculated for a given sigma LOV1. The second method of computing the impact solutions, called thereafter LOV2, is based on a non-uniformly sampling of the LOV. We showed that different methods of sampling the LOV can give different impact solutions, but all computed dates of possible impacts of the asteroid 2001 BB16 with the Earth occur in accordance at the end of the 22nd century.

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Formation and dynamics of Saturn and its disk simulated by using a new N-body model

Open Physics ◽

10.2478/bf02475908 ◽

2003 ◽

Vol 1 (4) ◽

Author(s):

A. Pavlov ◽

Y. Pavlova

Keyword(s):

Surface Density ◽

Electromagnetic Interaction ◽

The Core ◽

Body Model ◽

Magnetic Forces ◽

Axis Of Rotation ◽

Gravitational Model ◽

Minor Part ◽

Body Self ◽

A Minor

AbstractThe formation of Saturn and its disk is simulated using a new N-body self-gravitational model. It is demonstrated that the formation of the disk and the planet is the result of gravitational contraction of a slowly rotated particle cloud that have a shape of slightly deformed sphere. The sphere was flattened by a coefficient of 0.8 along the axis of rotation. During the gravitational contraction, the major part of the cloud transformed into a planet and a minor part transformed into a disk. The thin structured disk is a result of the electromagnetic interaction in which the magnetic forces acting on charged particles of the cloud originate in the core of the planet. The simulation program gives such parameters of Saturn as the escape velocity of about 35 km/s at the surface, density, rotational velocities of the rings and temperature distribution.

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The Tidal Potential of a Homogeneous Torus with an Elliptical Section of the Sleeve

Open Astronomy ◽

10.1515/astro-2017-0140 ◽

2016 ◽

Vol 25 (3) ◽

Author(s):

B. P. Kondratyev ◽

N. G. Trubitsyna

Keyword(s):

Cross Section ◽

Kuiper Belt ◽

Analytical Form ◽

Elliptical Cross Section ◽

External Region ◽

Elliptical Cross ◽

Tidal Potential ◽

Gravitational Model ◽

Elliptical Section

AbstractIn this paper the problem of the tidal potential of a homogeneous gravitating torus with an elliptical cross-section sleeve is solved. In particular, the potentials in analytical form in the vicinity of the center of the torus and its external region are found. This torus can serve as a gravitational model of the Kuiper belt.

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Lithium Observations in the Sun

Highlights of Astronomy ◽

10.1017/s1539299600001222 ◽

1968 ◽

Vol 1 ◽

pp. 243-246

Author(s):

Edith A. Müller

Keyword(s):

Unknown Origin ◽

Absorption Feature ◽

The Sun ◽

Degree Of Ionization ◽

Lithium Abundance ◽

Resonance Doublet ◽

Lower Temperature ◽

Central Depth ◽

The Continuum

The determination of the lithium abundance in the solar atmosphere is essentially based on the LiI resonance doublet at λ 6707·761 and 6707·912 Å. These two lines form a very faint absorption feature, the central depth of the stronger component being of the order of 1% of the continuum. The violet component, which is also the stronger of the two, occurs near the red wing of a faint solar line of unknown origin, and the lines appear to be blended with other faint lines including possibly the doublet of the Li6 isotope (the isotopic shift being 0·160 Å). No other line of LiI has been detected in the Fraunhofer spectum of the undisturbed solar disk. This is nothing surprising, because practically all lithium is expected to be ionized in the photosphere on account of its low ionization potential (Xion = 5·37 e.v.). In sunspot spectra the lower temperature reduces the degree of ionization of lithium and causes a strengthening of the LiI lines. In fact, the LiI resonance lines which appear as a very faint absorption feature on disk spectra are about 50 times stronger in spot spectra. Furthermore, the very weak feature at λ 6103·6 Å was identified by Dubov (1964) and by Schmahl and Schröter (1965) as due to the 2s 2S–3d 2D transition of LiI. Both the resonance doublet and the faint feature at 6103·6 Å have been used by the above-mentioned authors to derive the lithium abundance in spots.

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NGC 6124: a young open cluster with anomalous- and fast-rotating giant stars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab2836 ◽

2021 ◽

Author(s):

N Holanda ◽

N Drake ◽

W J B Corradi ◽

F A Ferreira ◽

F Maia ◽

...

Keyword(s):

Isotopic Ratio ◽

Rotational Velocity ◽

Open Cluster ◽

Chemical Species ◽

Stellar Atmospheres ◽

Lithium Abundance ◽

Giant Stars ◽

Analysis Technique ◽

Young Open Cluster ◽

Fast Rotating

Abstract We present the results of a chemical analysis of fast and anomalous rotator giants members of the young open cluster NGC 6124. For this purpose, we carried out abundances of the mixing sensitive species such as Li, C, N, Na and 12C/13C isotopic ratio, as well as other chemical species for a sample of four giants among the seven observed ones. This study is based on standard spectral analysis technique using high-resolution spectroscopic data. We also performed an investigation of the rotational velocity (v sin i) once this sample exhibit abnormal values – giant stars commonly present rotational velocities of few km s−1. In parallel, we have been performed a membership study, making use of the third data release from ESA Gaia mission. Based on these data, we estimated a distance of d = 630 pc and an age of 178 Myr through isochrone fitting. After that procedure, we matched all the information raised and investigated the evolutionary stages and thermohaline mixing model through of spectroscopic Teff and log g and mixing tracers, as 12C/13C and Na, of the studied stars. We derived a low mean metallicity of [Fe/H] = −0.13 ±0.05 and a modest enhancement of the elements created by the s-process such as Y, Zr, La, Ce, and Nd, which is in agreement of what has already been reported in the literature for young clusters. The giants analyzed have homogeneous abundances, except for lithium abundance [log ε(Li)NLTE = 1.08±0.42] and this may be associated to a combination of mechanisms that act increasing or decreasing lithium abundances in stellar atmospheres.

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Lithium Abundance of the Solar-Type Superflare Stars

Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016) ◽

10.7566/jpscp.14.020303 ◽

2017 ◽

Author(s):

Satoshi Honda ◽

Yuta Notsu ◽

Hiroyuki Maehara ◽

Shota Notsu ◽

Takuya Shibayama ◽

...

Keyword(s):

Lithium Abundance ◽

Solar Type

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Gravitational Model of a p-n Junction

The Physics Teacher ◽

10.1119/1.5064566 ◽

2018 ◽

Vol 56 (8) ◽

pp. 538-539

Author(s):

Victor E. Henrich

Keyword(s):

Gravitational Model

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The solar lithium abundance

Solar Physics ◽

10.1007/bf00152955 ◽

1975 ◽

Vol 41 (1) ◽

pp. 53-65 ◽

Cited By ~ 45

Author(s):

Edith A Müller ◽

Eric Peytremann ◽

Ramiro de la Reza

Keyword(s):

Lithium Abundance

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Li isotopes in metal-poor halo dwarfs: a more and more complicated story

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310004138 ◽

2009 ◽

Vol 5 (S268) ◽

pp. 201-210

Author(s):

Monique Spite ◽

François Spite

Keyword(s):

Cosmic Rays ◽

Big Bang ◽

The Other ◽

Big Bang Nucleosynthesis ◽

Lithium Abundance ◽

The Galaxy ◽

Li Isotope ◽

Low Metallicity ◽

The Big Bang ◽

Early Galaxy

AbstractThe nuclei of the lithium isotopes are fragile, easily destroyed, so that, at variance with most of the other elements, they cannot be formed in stars through steady hydrostatic nucleosynthesis.The 7Li isotope is synthesized during primordial nucleosynthesis in the first minutes after the Big Bang and later by cosmic rays, by novae and in pulsations of AGB stars (possibly also by the ν process). 6Li is mainly formed by cosmic rays. The oldest (most metal-deficient) warm galactic stars should retain the signature of these processes if, (as it had been often expected) lithium is not depleted in these stars. The existence of a “plateau” of the abundance of 7Li (and of its slope) in the warm metal-poor stars is discussed. At very low metallicity ([Fe/H] < −2.7dex) the star to star scatter increases significantly towards low Li abundances. The highest value of the lithium abundance in the early stellar matter of the Galaxy (logϵ(Li) = A(7Li) = 2.2 dex) is much lower than the the value (logϵ(Li) = 2.72) predicted by the standard Big Bang nucleosynthesis, according to the specifications found by the satellite WMAP. After gathering a homogeneous stellar sample, and analysing its behaviour, possible explanations of the disagreement between Big Bang and stellar abundances are discussed (including early astration and diffusion). On the other hand, possibilities of lower productions of 7Li in the standard and/or non-standard Big Bang nucleosyntheses are briefly evoked.A surprisingly high value (A(6Li)=0.8 dex) of the abundance of the 6Li isotope has been found in a few warm metal-poor stars. Such a high abundance of 6Li independent of the mean metallicity in the early Galaxy cannot be easily explained. But are we really observing 6Li?

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