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Register a new userOn the age and formation mechanism of the core of the Quadrantid meteoroid stream
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Abedin Yusein Abedin
Publication date
2015
fields
Physics
and research's language is
English
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The Quadrantid meteor shower is among the strongest annual meteor showers, and has drawn the attention of scientists for several decades. The stream is unusual, among others, for several reasons: its very short duration around maximum activity (~12 - 14 hours) as detected by visual, photographic and radar observations, its recent onset (around 1835 AD) and because it had been the only major stream without an obvious parent body until 2003. Ever since, there have been debates as to the age of the stream and the nature of its proposed parent body, asteroid 2003 EH1. In this work, we present results on the most probable age and formation mechanism of the narrow portion of the Quadrantid meteoroid stream. For the first time we use data on eight high precision photographic Quadrantids, equivalent to gram - kilogram size, to constrain the most likely age of the core of the stream. Out of eight high-precision photographic Quadrantids, five pertain directly to the narrow portion of the stream. In addition, we also use data on five high-precision radar Quadrantids, observed within the peak of the shower. We performed backwards numerical integrations of the equations of motion of a large number of clones of both, the eight high-precision photographic and five radar Quadrantid meteors, along with the proposed parent body, 2003 EH1. According to our results, from the backward integrations, the most likely age of the narrow structure of the Quadrantids is between 200 - 300 years. These presumed ejection epochs, corresponding to 1700 - 1800 AD, are then used for forward integrations of large numbers of hypothetical meteoroids, ejected from the parent 2003 EH$_1$, until the present epoch. The aim is to constrain whether the core of the Quadrantid meteoroid stream is consistent with a previously proposed relatively young age (~ 200 years).}
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The near-Earth asteroid (196256) 2003 EH1 has been suggested to have a dynamical association with the Quadrantid meteoroid stream. We present photometric observations taken to investigate the physical character of this body and to explore its possible relation to the stream. We find no evidence for on-going mass-loss. A model fitted to the point-like surface brightness profile at 2.1 AU limits the fractional contribution to the integrated brightness by near-nucleus coma to $leq$ 2.5 %. Assuming an albedo equal to those typical of cometary nuclei ($it p_{rm R}$=0.04), we find that the effective nucleus radius is $r_e$ = 2.0$pm$0.2 km. Time-resolved ${it R}$-band photometry can be fitted by a two-peaked lightcurve having a rotational period of 12.650$pm$0.033 hr. The range of the lightcurve, $Delta m_{rm R}$= 0.44 $pm$ 0 .01 mag, is indicative of an elongated shape having an axis ratio $sim$1.5 projected into the plane of the sky. The asteroid shows colors slightly redder than the Sun, being comparable with those of C-type asteroids. The limit to the mass loss rate set by the absence of resolved coma is $lesssim$ 2.5$times$ 10$^{-2}$ kg ${rm s^{-1}}$, corresponding to an upper limit on the fraction of the surface that could be sublimating water ice $f_A$ $lesssim$ 10$^{-4}$. Even if sustained over the 200-500 yr dynamical age of the Quadrantid stream, the total mass loss from 2003 EH1 would be too small to supply the reported stream mass ($10^{13}$ kg), implying either that the stream has another parent or that mass loss from 2003 EH1 is episodic.
[Abridged] Asteroid mining is not necessarily a distant prospect. Hayabusa2 and OSIRIS-REx have recently rendezvoused with near-Earth asteroids and will return samples to Earth. While there is significant science motivation for these missions, there are also resource interests. Space agencies and commercial entities are particularly interested in ices and water-bearing minerals that could be used to produce rocket fuel in space. The internationally coordinated roadmaps of major space agencies depend on utilizing the natural resources of such celestial bodies. Several companies have already created plans for intercepting and extracting water and minerals from near-Earth objects, as even a small asteroid could have high economic worth. However, the low surface gravity of asteroids could make the release of mining waste and the subsequent formation of debris streams a consequence of asteroid mining. Strategies to contain material during extraction could still eventually require the purposeful jettison of waste to avoid managing unwanted mass. Using simulations, we explore the formation of mining debris streams by integrating particles released from four select asteroids. Radiation effects are included, and a range of debris sizes are explored. The simulation results are used to investigate the timescales for debris stream formation, the sizes of the streams, and the meteoroid fluxes compared with sporadic meteoroids. We find that for prodigious mining activities resulting in the loss of a few percent of the asteroids mass or more, it is possible to produce streams that exceed the sporadic flux during stream crossing for some meteoroid sizes. The result of these simulations are intended to highlight potential unintended consequences that could result from NewSpace activity, which could help to inform efforts to develop international space resource guidelines.
The recent discoveries of massive planets on ultra-wide orbits of HR 8799 (Marois et al. 2008) and Fomalhaut (Kalas et al. 2008) present a new challenge for planet formation theorists. Our goal is to figure out which of three giant planet formation mechanisms--core accretion (with or without migration), scattering from the inner disk, or gravitational instability--could be responsible for Fomalhaut b, HR 8799 b, c and d, and similar planets discovered in the future. This paper presents the results of numerical experiments comparing the long-period planet formation efficiency of each possible mechanism in model A star, G star and M star disks. First, a simple core accretion simulation shows that planet cores forming beyond 35 AU cannot reach critical mass, even under the most favorable conditions one can construct. Second, a set of N-body simulations demonstrates that planet-planet scattering does not create stable, wide-orbit systems such as HR 8799. Finally, a linear stability analysis verifies previous work showing that global spiral instabilities naturally arise in high-mass disks. We conclude that massive gas giants on stable orbits with semimajor axes greater than 35 AU form by gravitational instability in the disk. We recommend that observers examine the planet detection rate as a function of stellar age, controlling for planet dimming with time. If planet detection rate is found to be independent of stellar age, it would confirm our prediction that gravitational instability is the dominant mode of producing detectable planets on wide orbits. We also predict that the occurrence ratio of long-period to short-period gas giants should be highest for M dwarfs due to the inefficiency of core accretion and the expected small fragment mass in their disks.
The Martian Moons Exploration (MMX) spacecraft is a JAXA mission to Mars and its moons Phobos and Deimos. MMX will carry the Circum-Martian Dust Monitor (CMDM) which is a newly developed light-weight ($mathrm{650,g}$) large area ($mathrm{1,m^2}$) dust impact detector. Cometary meteoroid streams (also referred to as trails) exist along the orbits of comets, forming fine structures of the interplanetary dust cloud. The streams consist predominantly of the largest cometary particles (with sizes of approximately $mathrm{100,mu m}$ to 1~cm) which are ejected at low speeds and remain very close to the comet orbit for several revolutions around the Sun. The Interplanetary Meteoroid Environment for eXploration (IMEX) dust streams in space model is a new and recently published universal model for cometary meteoroid streams in the inner Solar System. We use IMEX to study the detection conditions of cometary dust stream particles with CMDM during the MMX mission in the time period 2024 to 2028. The model predicts traverses of 12 cometary meteoroid streams with fluxes of $mathrm{100,mu m}$ and bigger particles of at least $mathrm{10^{-3},m^{-2},day^{-1}}$ during a total time period of approximately 90~days. The highest flux of $mathrm{0.15,m^{-2},day^{-1}}$ is predicted for comet 114P/Wiseman-Skiff in October 2026. With its large detection area and high sensitivity CMDM will be able to detect cometary meteoroid streams en route to Phobos. Our simulation results for the Mars orbital phase of MMX also predict the occurrence of meteor showers in the Martian atmosphere which may be observable from the Martian surface with cameras on board landers or rovers. Finally, the IMEX model can be used to study the impact hazards imposed by meteoroid impacts on to large-area spacecraft structures that will be particularly necessary for crewed deep space missions.
We have used moderate resolution, near-infrared spectra from the SpeX spectrograph on the NASA Infrared Telescope facility to characterize the stellar content of Barnard 59 (B59), the most active star-forming core in the Pipe Nebula. Measuring luminosity and temperature sensitive features in the spectra of 20 candidate YSOs, we identified likely background giant stars and measured each stars spectral type, extinction, and NIR continuum excess. We find that B59 is composed of late type (K4-M6) low-mass (0.9--0.1 M_sun) YSOs whose median stellar age is comparable to, if not slightly older than, that of YSOs within the Rho Oph, Taurus, and Chameleon star forming regions. Deriving absolute age estimates from pre-main sequence models computed by DAntona et al., and accounting only for statistical uncertainties, we measure B59s median stellar age to be 2.6+/-0.8 Myrs. Including potential systematic effects increases the error budget for B59s median (DM98) stellar age to 2.6+4.1/-2.6 Myrs. We also find that the relative age orderings implied by pre-main sequence evolutionary tracks depend on the range of stellar masses sampled, as model isochrones possess significantly different mass dependencies. The maximum likelihood median stellar age we measure for B59, and the regions observed gas properties, suggest that the B59 dense core has been stable against global collapse for roughly 6 dynamical timescales, and is actively forming stars with a star formation efficiency per dynamical time of ~6%. This maximum likelihood value agrees well with recent star formation simulations that incorporate various forms of support against collapse, such as sub-critical magnetic fields, outflows, and radiative feedback from protostellar heating. [abridged]
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