The Time of Perihelion Passage and the Longitude of Perihelion of Nemesis
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Wimps and Machos ENCYCLOPEDIA of ASTRONOMY and ASTROPHYSICS
WIMPs and MACHOs ENCYCLOPEDIA OF ASTRONOMY AND ASTROPHYSICS WIMPs and MACHOs objects that could be the dark matter and still escape detection. For example, if the Galactic halo were filled –3 . WIMP is an acronym for weakly interacting massive par- with Jupiter mass objects (10 Mo) they would not have ticle and MACHO is an acronym for massive (astrophys- been detected by emission or absorption of light. Brown . ical) compact halo object. WIMPs and MACHOs are two dwarf stars with masses below 0.08Mo or the black hole of the most popular DARK MATTER candidates. They repre- remnants of an early generation of stars would be simi- sent two very different but reasonable possibilities of larly invisible. Thus these objects are examples of what the dominant component of the universe may be. MACHOs. Other examples of this class of dark matter It is well established that somewhere between 90% candidates include primordial black holes created during and 99% of the material in the universe is in some as yet the big bang, neutron stars, white dwarf stars and vari- undiscovered form. This material is the gravitational ous exotic stable configurations of quantum fields, such glue that holds together galaxies and clusters of galaxies as non-topological solitons. and plays an important role in the history and fate of the An important difference between WIMPs and universe. Yet this material has not been directly detected. MACHOs is that WIMPs are non-baryonic and Since extensive searches have been done, this means that MACHOS are typically (but not always) formed from this mysterious material must not emit or absorb appre- baryonic material. -
Messier Objects
Messier Objects From the Stocker Astroscience Center at Florida International University Miami Florida The Messier Project Main contributors: • Daniel Puentes • Steven Revesz • Bobby Martinez Charles Messier • Gabriel Salazar • Riya Gandhi • Dr. James Webb – Director, Stocker Astroscience center • All images reduced and combined using MIRA image processing software. (Mirametrics) What are Messier Objects? • Messier objects are a list of astronomical sources compiled by Charles Messier, an 18th and early 19th century astronomer. He created a list of distracting objects to avoid while comet hunting. This list now contains over 110 objects, many of which are the most famous astronomical bodies known. The list contains planetary nebula, star clusters, and other galaxies. - Bobby Martinez The Telescope The telescope used to take these images is an Astronomical Consultants and Equipment (ACE) 24- inch (0.61-meter) Ritchey-Chretien reflecting telescope. It has a focal ratio of F6.2 and is supported on a structure independent of the building that houses it. It is equipped with a Finger Lakes 1kx1k CCD camera cooled to -30o C at the Cassegrain focus. It is equipped with dual filter wheels, the first containing UBVRI scientific filters and the second RGBL color filters. Messier 1 Found 6,500 light years away in the constellation of Taurus, the Crab Nebula (known as M1) is a supernova remnant. The original supernova that formed the crab nebula was observed by Chinese, Japanese and Arab astronomers in 1054 AD as an incredibly bright “Guest star” which was visible for over twenty-two months. The supernova that produced the Crab Nebula is thought to have been an evolved star roughly ten times more massive than the Sun. -
Black-Hole Binaries, Gravitational Waves, and Numerical Relativity
Black-hole binaries, gravitational waves, and numerical relativity Joan Centrella∗ and John G. Baker† Gravitational Astrophysics Laboratory, NASA/GSFC, 8800 Greenbelt Road, Greenbelt, Maryland 20771, USA Bernard J. Kelly‡ and James R. van Meter§ CRESST and Gravitational Astrophysics Laboratory, NASA/GSFC, 8800 Greenbelt Road, Greenbelt, Maryland 20771, USA and Department of Physics, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250, USA (Dated: November 30, 2010) Understanding the predictions of general relativity for the dynamical interactions of two black holes has been a long-standing unsolved problem in theoretical physics. Black-hole mergers are monu- mental astrophysical events, releasing tremendous amounts of energy in the form of gravitational radiation, and are key sources for both ground- and space-based gravitational-wave detectors. The black-hole merger dynamics and the resulting gravitational waveforms can only be calculated through numerical simulations of Einstein’s equations of general relativity. For many years, nu- merical relativists attempting to model these mergers encountered a host of problems, causing their codes to crash after just a fraction of a binary orbit could be simulated. Recently, however, a series of dramatic advances in numerical relativity has allowed stable, robust black-hole merger simulations. This remarkable progress in the rapidly maturing field of numerical relativity, and the new understanding of black-hole binary dynamics that is emerging is chronicled. Important applications of these fundamental physics results to astrophysics, to gravitational-wave astronomy, and in other areas are also discussed. Contents G. Numerical Approximation Methods 15 H. Extracting the Physics 15 I. Prelude 2 V. Black-Hole Merger Dynamics and Waveforms 16 II. -
Are Gamma-Ray Bursts Signals of Supermassive Black Hole Formation?
Are Gamma-Ray Bursts Signals of Supermassive Black Hole Formation? K. Abazajian, G. Fuller, X. Shi Department of Physics, University of California, San Diego, La Jolla, California 92093-0350 Abstract. The formation of supermassive black holes through the gravitational 4 collapse of supermassive objects (M ∼> 5 × 10 M⊙) has been proposed as a source of cosmological γ-ray bursts. The major advantage of this model is that such collapses are far more energetic than stellar-remnant mergers. The major drawback of this idea is the severe baryon loading problem in one-dimensional models. We can show that the observed log N − log P (number vs. peak flux) distribution for gamma-ray bursts in the BATSE database is not inconsistent with an identification of supermassive object collapse as the origin of the gamma-ray bursts. This conclusion is valid for a range of plausible cosmological and γ-ray burst spectral parameters. 1. Introduction We investigate aspects of a recent model for the internal engine powering γ-ray bursts (GRBs). This model produces a GRB fireball through neutrino emission and annihilation during the collapse of a supermassive object into a black hole (Fuller & Shi, 1998). This supermassive object may either be a relativistic cluster of stars or a single supermassive star. The collapse of a supermassive object provides an exceedingly large amount of energy to power the burst, much higher than the amount of energy available in stellar remnant models. In addition, the rate of collapse of these objects–when associated with galaxy-type structures–is arXiv:astro-ph/9812287v1 15 Dec 1998 similar to the GRB rate. -
Gamma Ray Bursts from Stellar Collisions
CORE Metadata, citation and similar papers at core.ac.uk Provided by CERN Document Server Gamma Ray Bursts from Stellar Collisions Brad M.S. Hansen & Chigurupati Murali Canadian Institute for Theoretical Astrophysics University of Toronto, Toronto, ON M5S 3H8, Canada Received ; accepted –2– ABSTRACT We propose that the cosmological gamma ray bursts arise from the collapse of neutron stars to black holes triggered by collisions or mergers with main sequence stars. This scenario represents a cosmological history qualitatively different from most previous theories because it contains a significant contribution from an old stellar population, namely the globular clusters. Furthermore, the gas poor central regions of globular clusters provide an ideal environment for the generation of the recently confirmed afterglows via the fireball scenario. Collisions resulting from neutron star birth kicks in close binaries may also contribute to the overall rate and should lead to associations between some gamma ray bursts and supernovae of type Ib/c. Subject headings: stars:neutron–supernovae:general–globular clusters:general– gamma rays:bursts– Galaxy:evolution –3– 1. Introduction The detection of X-ray, optical and radio afterglows from gamma-ray burst events (Costa et al 1997; van Paradijs et al 1997, Sahu et al 1997; Frail et al 1997) and concommitant redshifts (Metzger et al 1997) has provided strong support for the cosmological origin of the phenomenon. The success of the fireball model (Cavallo & Rees 1978; Rees & Meszaros 1992; Meszaros & Rees 1993) is largely independent of the origin of the energy, requiring only an energetic and baryon-poor event confined to small scales, thereby giving rise to a relativistic and optically thick outflow. -
The Solar System
5 The Solar System R. Lynne Jones, Steven R. Chesley, Paul A. Abell, Michael E. Brown, Josef Durech,ˇ Yanga R. Fern´andez,Alan W. Harris, Matt J. Holman, Zeljkoˇ Ivezi´c,R. Jedicke, Mikko Kaasalainen, Nathan A. Kaib, Zoran Kneˇzevi´c,Andrea Milani, Alex Parker, Stephen T. Ridgway, David E. Trilling, Bojan Vrˇsnak LSST will provide huge advances in our knowledge of millions of astronomical objects “close to home’”– the small bodies in our Solar System. Previous studies of these small bodies have led to dramatic changes in our understanding of the process of planet formation and evolution, and the relationship between our Solar System and other systems. Beyond providing asteroid targets for space missions or igniting popular interest in observing a new comet or learning about a new distant icy dwarf planet, these small bodies also serve as large populations of “test particles,” recording the dynamical history of the giant planets, revealing the nature of the Solar System impactor population over time, and illustrating the size distributions of planetesimals, which were the building blocks of planets. In this chapter, a brief introduction to the different populations of small bodies in the Solar System (§ 5.1) is followed by a summary of the number of objects of each population that LSST is expected to find (§ 5.2). Some of the Solar System science that LSST will address is presented through the rest of the chapter, starting with the insights into planetary formation and evolution gained through the small body population orbital distributions (§ 5.3). The effects of collisional evolution in the Main Belt and Kuiper Belt are discussed in the next two sections, along with the implications for the determination of the size distribution in the Main Belt (§ 5.4) and possibilities for identifying wide binaries and understanding the environment in the early outer Solar System in § 5.5. -
Theoretical Orbits of Planets in Binary Star Systems 1
Theoretical Orbits of Planets in Binary Star Systems 1 Theoretical Orbits of Planets in Binary Star Systems S.Edgeworth 2001 Table of Contents 1: Introduction 2: Large external orbits 3: Small external orbits 4: Eccentric external orbits 5: Complex external orbits 6: Internal orbits 7: Conclusion Theoretical Orbits of Planets in Binary Star Systems 2 1: Introduction A binary star system consists of two stars which orbit around their joint centre of mass. A large proportion of stars belong to such systems. What sorts of orbits can planets have in a binary star system? To examine this question we use a computer program called a multi-body gravitational simulator. This enables us to create accurate simulations of binary star systems with planets, and to analyse how planets would really behave in this complex environment. Initially we examine the simplest type of binary star system, which satisfies these conditions:- 1. The two stars are of equal mass. 2, The two stars share a common circular orbit. 3. Planets orbit on the same plane as the stars. 4. Planets are of negligible mass. 5. There are no tidal effects. We use the following units:- One time unit = the orbital period of the star system. One distance unit = the distance between the two stars. We can classify possible planetary orbits into two types. A planet may have an internal orbit, which means that it orbits around just one of the two stars. Alternatively, a planet may have an external orbit, which means that its orbit takes it around both stars. Also a planet's orbit may be prograde (in the same direction as the stars' orbits ), or retrograde (in the opposite direction to the stars' orbits). -
Binary and Multiple Systems of Asteroids
Binary and Multiple Systems Andrew Cheng1, Andrew Rivkin2, Patrick Michel3, Carey Lisse4, Kevin Walsh5, Keith Noll6, Darin Ragozzine7, Clark Chapman8, William Merline9, Lance Benner10, Daniel Scheeres11 1JHU/APL [[email protected]] 2JHU/APL [[email protected]] 3University of Nice-Sophia Antipolis/CNRS/Observatoire de la Côte d'Azur [[email protected]] 4JHU/APL [[email protected]] 5University of Nice-Sophia Antipolis/CNRS/Observatoire de la Côte d'Azur [[email protected]] 6STScI [[email protected]] 7Harvard-Smithsonian Center for Astrophysics [[email protected]] 8SwRI [[email protected]] 9SwRI [[email protected]] 10JPL [[email protected]] 11Univ Colorado [[email protected]] Abstract A sizable fraction of small bodies, including roughly 15% of NEOs, is found in binary or multiple systems. Understanding the formation processes of such systems is critical to understanding the collisional and dynamical evolution of small body systems, including even dwarf planets. Binary and multiple systems provide a means of determining critical physical properties (masses, densities, and rotations) with greater ease and higher precision than is available for single objects. Binaries and multiples provide a natural laboratory for dynamical and collisional investigations and may exhibit unique geologic processes such as mass transfer or even accretion disks. Missions to many classes of planetary bodies – asteroids, Trojans, TNOs, dwarf planets – can offer enhanced science return if they target binary or multiple systems. Introduction Asteroid lightcurves were often interpreted through the 1970s and 1980s as showing evidence for satellites, and occultations of stars by asteroids also provided tantalizing if inconclusive hints that asteroid satellites may exist. -
1 on the Origin of the Pluto System Robin M. Canup Southwest Research Institute Kaitlin M. Kratter University of Arizona Marc Ne
On the Origin of the Pluto System Robin M. Canup Southwest Research Institute Kaitlin M. Kratter University of Arizona Marc Neveu NASA Goddard Space Flight Center / University of Maryland The goal of this chapter is to review hypotheses for the origin of the Pluto system in light of observational constraints that have been considerably refined over the 85-year interval between the discovery of Pluto and its exploration by spacecraft. We focus on the giant impact hypothesis currently understood as the likeliest origin for the Pluto-Charon binary, and devote particular attention to new models of planet formation and migration in the outer Solar System. We discuss the origins conundrum posed by the system’s four small moons. We also elaborate on implications of these scenarios for the dynamical environment of the early transneptunian disk, the likelihood of finding a Pluto collisional family, and the origin of other binary systems in the Kuiper belt. Finally, we highlight outstanding open issues regarding the origin of the Pluto system and suggest areas of future progress. 1. INTRODUCTION For six decades following its discovery, Pluto was the only known Sun-orbiting world in the dynamical vicinity of Neptune. An early origin concept postulated that Neptune originally had two large moons – Pluto and Neptune’s current moon, Triton – and that a dynamical event had both reversed the sense of Triton’s orbit relative to Neptune’s rotation and ejected Pluto onto its current heliocentric orbit (Lyttleton, 1936). This scenario remained in contention following the discovery of Charon, as it was then established that Pluto’s mass was similar to that of a large giant planet moon (Christy and Harrington, 1978). -
Arxiv:2012.04712V1 [Astro-Ph.EP] 8 Dec 2020 Direct Evidence of the Presence of Planets (E.G., ALMA Part- Nership Et Al
DRAFT VERSION DECEMBER 10, 2020 Typeset using LATEX twocolumn style in AASTeX63 First detection of orbital motion for HD 106906 b: A wide-separation exoplanet on a Planet Nine-like orbit MEIJI M. NGUYEN,1 ROBERT J. DE ROSA,2 AND PAUL KALAS1, 3, 4 1Department of Astronomy, University of California, Berkeley, CA 94720, USA 2European Southern Observatory, Alonso de Cordova´ 3107, Vitacura, Santiago, Chile 3SETI Institute, Carl Sagan Center, 189 Bernardo Ave., Mountain View, CA 94043, USA 4Institute of Astrophysics, FORTH, GR-71110 Heraklion, Greece (Received August 26, 2020; Revised October 8, 2020; Accepted October 10, 2020) Submitted to AJ ABSTRACT HD 106906 is a 15 Myr old short-period (49 days) spectroscopic binary that hosts a wide-separation (737 au) planetary-mass ( 11 M ) common proper motion companion, HD 106906 b. Additionally, a circumbinary ∼ Jup debris disk is resolved at optical and near-infrared wavelengths that exhibits a significant asymmetry at wide separations that may be driven by gravitational perturbations from the planet. In this study we present the first detection of orbital motion of HD 106906 b using Hubble Space Telescope images spanning a 14 yr period. We achieve high astrometric precision by cross-registering the locations of background stars with the Gaia astromet- ric catalog, providing the subpixel location of HD 106906 that is either saturated or obscured by coronagraphic optical elements. We measure a statistically significant 31:8 7:0 mas eastward motion of the planet between ± the two most constraining measurements taken in 2004 and 2017. This motion enables a measurement of the +27 +27 inclination between the orbit of the planet and the inner debris disk of either 36 14 deg or 44 14 deg, depending on the true orientation of the orbit of the planet. -
Why Pluto Is Not a Planet Anymore Or How Astronomical Objects Get Named
3 Why Pluto Is Not a Planet Anymore or How Astronomical Objects Get Named Sethanne Howard USNO retired Abstract Everywhere I go people ask me why Pluto was kicked out of the Solar System. Poor Pluto, 76 years a planet and then summarily dismissed. The answer is not too complicated. It starts with the question how are astronomical objects named or classified; asks who is responsible for this; and ends with international treaties. Ultimately we learn that it makes sense to demote Pluto. Catalogs and Names WHO IS RESPONSIBLE for naming and classifying astronomical objects? The answer varies slightly with the object, and history plays an important part. Let us start with the stars. Most of the bright stars visible to the naked eye were named centuries ago. They generally have kept their old- fashioned names. Betelgeuse is just such an example. It is the eighth brightest star in the northern sky. The star’s name is thought to be derived ,”Yad al-Jauzā' meaning “the Hand of al-Jauzā يد الجوزاء from the Arabic i.e., Orion, with mistransliteration into Medieval Latin leading to the first character y being misread as a b. Betelgeuse is its historical name. The star is also known by its Bayer designation − ∝ Orionis. A Bayeri designation is a stellar designation in which a specific star is identified by a Greek letter followed by the genitive form of its parent constellation’s Latin name. The original list of Bayer designations contained 1,564 stars. The Bayer designation typically assigns the letter alpha to the brightest star in the constellation and moves through the Greek alphabet, with each letter representing the next fainter star. -
Chapter 5 Galaxies and Star Systems
Chapter 5 Galaxies and Star Systems Section 5.1 Galaxies Terms: • Galaxy • Spiral Galaxy • Elliptical Galaxy • Irregular Galaxy • Milky Way Galaxy • Quasar • Black Hole Types of Galaxies A galaxy is a huge group of single stars, star systems, star clusters, dust, and gas bound together by gravity. There are billions of galaxies in the universe. The largest galaxies have more than a trillion stars! Astronomers classify most galaxies into the following types: spiral, elliptical, and irregular. Spiral galaxies are those that appear to have a bulge in the middle and arms that spiral outward, like pinwheels. The spiral arms contain many bright, young stars as well as gas and dust. Most new stars in the spiral galaxies form in theses spiral arms. Relatively few new stars form in the central bulge. Some spiral galaxies, called barred-spiral galaxies, have a huge bar-shaped region of stars and gas that passes through their center. Not all galaxies have spiral arms. Elliptical galaxies look like round or flattened balls. These galaxies contain billions of the stars but have little gas and dust between the stars. Because there is little gas or dust, stars are no longer forming. Most elliptical galaxies contain only old stars. Some galaxies do not have regular shapes, thus they are called irregular galaxies. These galaxies are typically smaller than other types of galaxies and generally have many bright, young stars. They contain a lot of gas a dust to from new stars. The Milky Way Galaxy Although it is difficult to know what the shape of the Milky Way Galaxy is because we are inside of it, astronomers have identified it as a typical spiral galaxy.