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Maria Hajdukova - One of the best experts on this subject based on the ideXlab platform.
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frequency of hyperbolic and interstellar meteoroids
Meteoritics & Planetary Science, 2014Co-Authors: Maria Hajdukova, Leonard Kornos, Juraj TothAbstract:Hyperbolic meteor orbits from the catalog of 64,650 meteors observed by the multistation video meteor network located in Japan (SonotaCo 2009) have been investigated with the aim of determining the relation between the frequency of hyperbolic and interstellar meteors. The proportion of hyperbolic meteors in the data decreased significantly (from 11.58% to 3.28%) after a selection of quality orbits, which shows its dependence on the quality of observations. Initially, the hyperbolic orbits were searched for meteors unbound due to planetary perturbation. It was determined that 22 meteors from the 7489 hyperbolic orbits in the catalog (and 2 from the selection of the orbits with the highest quality) had had a close encounter with a planet, none of which, however, produced essential changes in their orbits. Similarly, the fraction of hyperbolic orbits in the data, which could be hyperbolic by reason of a meteor's interstellar origin, was determined to be at most 3.9 × 10−2. From the statistical point of view, the vast majority of hyperbolic meteors in the database have definitely been caused by inaccuracy in the Velocity determination. This fact does not necessarily assume great measurement errors, since, especially near the parabolic limit, a small error in the value of the Heliocentric Velocity of a meteor can create an artificial hyperbolic orbit that does not really exist. The results show that the remaining 96% of meteoroids with apparent hyperbolic orbits belong to the solar system meteoroid population. This is also supported by their high abundance (about 50%) among the meteor showers.
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interstellar meteoroids in the japanese tv catalogue
Publications of the Astronomical Society of Japan, 2011Co-Authors: Maria HajdukovaAbstract:The present work is based on an analysis of the 14763 precise determined meteor orbits collected in the Japanese tv catalogue (SonotaCo 2009), with the aim of determining the real proportion of interstellar meteors in this database. If interstellar meteors are present among the registered meteor orbits, the distribution of the excesses of their Heliocentric velocities should correspond to the distribution of the radial velocities of close stars. For the Velocity vi = 20 km s 1 of an interstellar meteor, with respect to the Sun, we obtain a Heliocentric Velocity of vH = 46.6 km s 1 of an interstellar meteor arriving at Earth. Any error in the determination of vH , especially near the parabolic limit, can create an artificial hyperbolic orbit that does not really exist. The analysis of the data did not produce any convincing arguments in favour of the existence of true hyperbolic meteors in the catalogue. It was shown that the vast majority of the 484 hyperbolic orbits has been caused by an overestimation of their Velocity, and approximately 50% of them belong to meteor showers. Furthermore, the hyperbolic excesses of the velocities in all cases are very low, about one order less than the Velocity distribution of neighbouring stars suggest. The upper limit of the proportion of possible interstellar meteors to interplanetary ones among all investigated meteor orbits in the database is 1.3 10 .
T S Li - One of the best experts on this subject based on the ideXlab platform.
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ships passing in the night spectroscopic analysis of two ultra faint satellites in the constellation carina
The Astrophysical Journal, 2018Co-Authors: T S Li, J D Simon, A B Pace, G Torrealba, K Kuehn, A Drlicawagner, K Bechtol, A K Vivas, R P Van Der MarelAbstract:We present Magellan/IMACS, Anglo-Australian Telescope/AAOmega+2dF, and Very Large Telescope/GIRAFFE+FLAMES spectroscopy of the CarinaII (Car II) & Carina III (Car III) dwarf galaxy candidates, recently discovered in the Magellanic Satellites Survey (MagLiteS). We identify 18 member stars in Car II, including 2 binaries with variable radial velocities and 2 RR Lyrae stars. The other 14 members have a mean Heliocentric Velocity $v_{\rm hel} = 477.2 \pm 1.2$ km/s and a Velocity dispersion of $\sigma_v = 3.4^{+1.2}_{-0.8}$ km/s. Assuming Car II is in dynamical equilibrium, we derive a total mass within the half-light radius of $1.0^{+0.8}_{-0.4} \times 10^{6} M_\odot$, indicating a mass-to-light ratio of $369^{+309}_{-161} M_\odot/L_\odot$. From equivalent width measurements of the calcium triplet lines of 9 RGB stars, we derive a mean metallicity of [Fe/H] = $-2.44 \pm 0.09$ with dispersion $\sigma_{\rm [Fe/H]} = 0.22 ^{+0.10}_{-0.07}$. Considering both the kinematic and chemical properties, we conclude that Car II is a dark-matter-dominated dwarf galaxy. For Car III, we identify 4 member stars, from which we calculate a systemic Velocity of $v_{\rm hel} = 284.6^{+3.4}_{-3.1}$ km/s. The brightest RGB member of Car III has a metallicity of [Fe/H] $= -1.97 \pm 0.12$. Due to the small size of the Car III spectroscopic sample, we cannot conclusively determine its nature. Although these two systems have the smallest known physical separation ($\Delta d\sim10~kpc$) among Local Group satellites, the large difference in their systemic velocities, $\sim200$ km/s, indicates that they are unlikely to be a bound pair. One or both systems are likely associated with the Large Magellanic Cloud (LMC), and may remain LMC satellites today. No statistically significant excess of $\gamma$-rays emission is found at the locations of Car II and Car III in eight years of Fermi-LAT data.
Bodewits Dennis - One of the best experts on this subject based on the ideXlab platform.
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Atomic iron and nickel in the coma of C/1996 B2 (Hyakutake): production rates, emission mechanisms, and possible parents
2021Co-Authors: Bromley Steven, Neff Brynna, Loch Stuart, Marler Joan, Országh Juraj, Venkataramani Kumar, Bodewits DennisAbstract:\noindent Recently, it has been discovered that gaseous nickel and iron is present in most comets. To evaluate the state of the laboratory data in support of these identifications, we re-analyzed archived spectra of comet C/1996 B2 (Hyakutake), one of the nearest and brightest comets of the last century, using a combined experimental and computational approach. We developed a new, many-level fluorescence model that indicates that the fluorescence emission of Fe I and Ni I vary greatly with Heliocentric Velocity. Combining this model with laboratory spectra of an Fe-Ni plasma, we identified 23 lines of Fe I and 14 lines of Ni I in the spectrum of Hyakutake. Using Haser models, we estimate the nickel and iron production rates as $Q_\textrm{Ni} = 2.6 - 4.1\times10^{22}$~s$^{-1}$ and $Q_\textrm{Fe} = 0.4 - 2.6\times10^{23}$~s$^{-1}$. From derived column densities the Ni/Fe abundance ratio log$_{10}$[Ni/Fe] = $-0.38\pm0.06$ deviates significantly from solar, and it is consistent with the ratios observed in solar system comets. Spectra from several offset distances show profiles consistent with a short-lived parent and/or emissive photodissociation of an unknown parent species. Possible production and emission mechanisms are analyzed in context of existing laboratory measurements. Based on the observed spatial distributions, excellent fluorescence model agreement, and Ni/Fe ratio, our findings support an origin consisting of dissociation of an unknown parent followed by fluorescence emission. Our findings suggest that the strong Heliocentric Velocity dependence of the fluorescence efficiencies can provide a meaningful test of the physical process responsible for the Fe I and Ni I emission.Comment: 23 pages, 11 figure
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Atomic iron and nickel in the coma of C/1996 B2 (Hyakutake): production rates, emission mechanisms, and possible parents
2021Co-Authors: Bromley Steven, Neff Brynna, Loch Stuart, Marler Joan, Országh Juraj, Venkataramani Kumar, Bodewits DennisAbstract:Two papers recently reported the detection of gaseous nickel and iron in the comae of over 20 comets from observations collected over two decades, including interstellar comet 2I/Borisov. To evaluate the state of the laboratory data in support of these identifications, we re-analyzed archived spectra of comet C/1996 B2 (Hyakutake), one of the nearest and brightest comets of the last century, using a combined experimental and computational approach. We developed a new, many-level fluorescence model that indicates that the fluorescence emission of Fe I and Ni I vary greatly with Heliocentric Velocity. Combining this model with laboratory spectra of an Fe-Ni plasma, we identified 22 lines of Fe I and 14 lines of Ni I in the spectrum of Hyakutake. Using Haser models, we estimate the nickel and iron production rates as Q(Ni) = 2.6 - 4.1 x 10^22 s^-1 and Q(Fe) = 0.4 - 2.8 x 10^23 s^-1. From derived column densities, the Ni/Fe abundance ratio log10[Ni/Fe] = -0.15 +/- 0.07 deviates significantly from solar abundance ratios, and it is consistent with the ratios observed in solar system comets. Possible production and emission mechanisms are analyzed in context of existing laboratory measurements. Based on the observed spatial distributions, excellent fluorescence model agreement, and Ni/Fe ratio, our findings support an origin consisting of a short-lived unknown parent followed by fluorescence emission. Our models suggest that the strong Heliocentric Velocity dependence of the fluorescence efficiencies can provide a meaningful test of the physical process responsible for the Fe I and Ni I emission.Comment: 23 pages, 11 figure
R P Van Der Marel - One of the best experts on this subject based on the ideXlab platform.
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ships passing in the night spectroscopic analysis of two ultra faint satellites in the constellation carina
The Astrophysical Journal, 2018Co-Authors: T S Li, J D Simon, A B Pace, G Torrealba, K Kuehn, A Drlicawagner, K Bechtol, A K Vivas, R P Van Der MarelAbstract:We present Magellan/IMACS, Anglo-Australian Telescope/AAOmega+2dF, and Very Large Telescope/GIRAFFE+FLAMES spectroscopy of the CarinaII (Car II) & Carina III (Car III) dwarf galaxy candidates, recently discovered in the Magellanic Satellites Survey (MagLiteS). We identify 18 member stars in Car II, including 2 binaries with variable radial velocities and 2 RR Lyrae stars. The other 14 members have a mean Heliocentric Velocity $v_{\rm hel} = 477.2 \pm 1.2$ km/s and a Velocity dispersion of $\sigma_v = 3.4^{+1.2}_{-0.8}$ km/s. Assuming Car II is in dynamical equilibrium, we derive a total mass within the half-light radius of $1.0^{+0.8}_{-0.4} \times 10^{6} M_\odot$, indicating a mass-to-light ratio of $369^{+309}_{-161} M_\odot/L_\odot$. From equivalent width measurements of the calcium triplet lines of 9 RGB stars, we derive a mean metallicity of [Fe/H] = $-2.44 \pm 0.09$ with dispersion $\sigma_{\rm [Fe/H]} = 0.22 ^{+0.10}_{-0.07}$. Considering both the kinematic and chemical properties, we conclude that Car II is a dark-matter-dominated dwarf galaxy. For Car III, we identify 4 member stars, from which we calculate a systemic Velocity of $v_{\rm hel} = 284.6^{+3.4}_{-3.1}$ km/s. The brightest RGB member of Car III has a metallicity of [Fe/H] $= -1.97 \pm 0.12$. Due to the small size of the Car III spectroscopic sample, we cannot conclusively determine its nature. Although these two systems have the smallest known physical separation ($\Delta d\sim10~kpc$) among Local Group satellites, the large difference in their systemic velocities, $\sim200$ km/s, indicates that they are unlikely to be a bound pair. One or both systems are likely associated with the Large Magellanic Cloud (LMC), and may remain LMC satellites today. No statistically significant excess of $\gamma$-rays emission is found at the locations of Car II and Car III in eight years of Fermi-LAT data.
Juraj Toth - One of the best experts on this subject based on the ideXlab platform.
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frequency of hyperbolic and interstellar meteoroids
Meteoritics & Planetary Science, 2014Co-Authors: Maria Hajdukova, Leonard Kornos, Juraj TothAbstract:Hyperbolic meteor orbits from the catalog of 64,650 meteors observed by the multistation video meteor network located in Japan (SonotaCo 2009) have been investigated with the aim of determining the relation between the frequency of hyperbolic and interstellar meteors. The proportion of hyperbolic meteors in the data decreased significantly (from 11.58% to 3.28%) after a selection of quality orbits, which shows its dependence on the quality of observations. Initially, the hyperbolic orbits were searched for meteors unbound due to planetary perturbation. It was determined that 22 meteors from the 7489 hyperbolic orbits in the catalog (and 2 from the selection of the orbits with the highest quality) had had a close encounter with a planet, none of which, however, produced essential changes in their orbits. Similarly, the fraction of hyperbolic orbits in the data, which could be hyperbolic by reason of a meteor's interstellar origin, was determined to be at most 3.9 × 10−2. From the statistical point of view, the vast majority of hyperbolic meteors in the database have definitely been caused by inaccuracy in the Velocity determination. This fact does not necessarily assume great measurement errors, since, especially near the parabolic limit, a small error in the value of the Heliocentric Velocity of a meteor can create an artificial hyperbolic orbit that does not really exist. The results show that the remaining 96% of meteoroids with apparent hyperbolic orbits belong to the solar system meteoroid population. This is also supported by their high abundance (about 50%) among the meteor showers.