اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدHow Sedna and family were captured in a close encounter with a solar sibling
111
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The discovery of 2012VP113 initiated the debate on the origin of the Sedna family of planetesimals in orbit around the Sun. Sednitos roam the outer regions of the Solar System between the Egeworth--Kuiper belt and the Oort cloud, in extraordinary wide (a>150au) orbits with a large perihelion distance of q>30au compared to the Earths (a=1au and eccentricity e=(1-q/a) ~ 0.0167 or q=1au). This population is composed of a dozen objects, which we consider a family because they have similar perihelion distance and inclination with respect to the ecliptic i=10--30deg. They also have similar argument of perihelion omega=340+/-55deg. There is no ready explanation for their origin. Here we show that these orbital parameters are typical for a captured population from the planetesimal disk of another star.Assuming the orbital elements of Sednitos have not changed since they acquired their orbits, we reconstruct the encounter that led to their capture. We conclude that they might have been captured in a near miss with a 1.8MSun star that impacted the Sun at ~340au at an inclination with respect to the ecliptic of 17--34deg with a relative velocity at infinity of ~4.3km/s. We predict that the Sednitos-region is populated by 930 planetesimals and the inner Oort cloud acquired ~440 planetesimals through the same encounter.
قيم البحث
اقرأ أيضاً
The dynamics of planetesimals plays an important role in planet formation, because their velocity distribution sets the growth rate to larger bodies. When planetesimals form in protoplanetary discs, their orbits are nearly circular and planar due to
the effect of gas drag. However, mutual close encounters of the planetesimals increase eccentricities and inclinations until an equilibrium between stirring and damping is reached. After disc dissipation, there is no more gas drag and mutual close encounters as well as encounters with planets stir the orbits again. The high number of planetesimals in protoplanetary discs renders it difficult to simulate their dynamics by means of direct N-body simulations of planet formation. Therefore, we developed a novel method for the dynamical evolution of planetesimals that is based on following close encounters between planetesimal-mass bodies and gravitational stirring by planet-mass bodies. To separate the orbital motion from the close encounters, we employ a Hamiltonian splitting scheme as used in symplectic N-body integrators. Close encounters are identified using a cell algorithm with linear scaling in the number of bodies. A grouping algorithm is used to create small groups of interacting bodies which are integrated separately. Our method allows simulating a high number of planetesimals interacting through gravity and collisions with low computational cost. The typical computational time is of the order of minutes or hours, up to a few days for more complex simulations, as compared to several hours or even weeks for the same setup with full N-body. The dynamical evolution of the bodies is sufficiently well reproduced. This will make it possible to study the growth of planetesimals through collisions and pebble accretion coupled to their dynamics for a much higher number of bodies than previously accessible with full N-body simulations.
We have used (a) HST ACS imaging and STIS spectroscopy, (b) ground-based PIONIER/VLT long-baseline interferometry, and (c) ground-based spectroscopy from different instruments to study the orbit of the extreme multiple system HD 93 129 Aa,Ab, which i
s composed of (at least) two very massive stars in a long-period orbit with e>0.92 that will pass through periastron in 2017/2018. In several ways, the system is an eta Car precursor. Around the time of periastron passage the two very strong winds will collide and generate an outburst of non-thermal hard X-ray emission without precedent in an O+O binary since astronomers have been able to observe above Earths atmosphere. A coordinated multiwavelength monitoring in the next two years will enable a breakthrough understanding of the wind interactions in such extreme close encounters. Furthermore, we have found evidence that HD 93 129 Aa may be a binary system itself. In that case, we could witness a three-body interaction that may yield a runaway star or a stellar collision close to or shortly after the periastron passage. Either of those outcomes would be unprecedented, as they are predicted to be low-frequency events in the Milky Way.
Next year, 2015, the New Horizons spacecraft will have a close encounter with Pluto. In the present study we discuss some possibilities regarding what the spacecraft may encounter during its approach to Pluto. Among them we should include: the presen
ce of geological activity due to heat generated by tides; the unlikely presence of an intrinsic magnetic field; the possibility of a plasmasphere and a plasmapause; the position of an ionopause; the existence of an ionospheric trans-terminator flow similar to that at Venus and Mars; and the presence of a Magnus force that produces a deflection of Pluto plasma wake. This deflection oscillates up and down in its orbit around the sun.
Parker Solar Probe (PSP) aims at exploring the nascent solar wind close to the Sun. Meanwhile, PSP is also expected to encounter small objects like comets and asteroids. In this work, we survey the ephemerides to find a chance of recent encounter, an
d then model the interaction between released dusty plasmas and solar wind plasmas. On 2019 September 2, a comet-like object 322P/SOHO just passed its perihelion flying to a heliocentric distance of 0.12 au, and swept by PSP at a relative distance as close as 0.025 au. We present the dynamics of dust particles released from 322P, forming a curved dust tail. Along the PSP path in the simulated inner heliosphere, the states of plasma and magnetic field are sampled and illustrated, with the magnetic field sequences from simulation results being compared directly with the in-situ measurements from PSP. Through comparison, we suggest that 322P might be at a deficient activity level releasing limited dusty plasmas during its way to becoming a rock comet. We also present images of solar wind streamers as recorded by WISPR, showing an indication of dust bombardment for the images superposed with messy trails. We observe from LASCO coronagraph that 322P was transiting from a dimming region to a relatively bright streamer during its perihelion passage, and simulate to confirm that 322P was flying from relatively faster to slower solar wind streams, modifying local plasma states of the streams.
A compact gas cloud G2 is predicted to reach the pericenter of its orbit around the super massive black hole (SMBH) of our galaxy, Sagittarius A* (Sgr A*). This event will give us a rare opportunity to observe the interaction between SMBH and gas aro
und it. We report the result of the fully three-dimensional simulation of the evolution of G2 during the first pericenter passage. The strong tidal force by the SMBH stretches the cloud along its orbit, and compresses it strongly in the vertical direction, resulting in the heating up and flaring up of the cloud. The bolometric luminosity will reach the maximum of $sim100 L_{odot}$. This flare should be easily observed in the near infrared.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
