Star Clusters and Stellar Dynamics
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The Solar System and Its Place in the Galaxy in Encyclopedia of the Solar System by Paul R
Giant Molecular Clouds http://www.astro.ncu.edu.tw/irlab/projects/project.htm Æ Galactic Open Clusters Æ Galactic Structure Æ GMCs The Solar System and its Place in the Galaxy In Encyclopedia of the Solar System By Paul R. Weissman http://www.academicpress.com/refer/solar/Contents/chap1.htm Stars in the galactic disk have different characteristic velocities as a function of their stellar classification, and hence age. Low-mass, older stars, like the Sun, have relatively high random velocities and as a result c an move farther out of the galactic plane. Younger, more massive stars have lower mean velocities and thus smaller scale heights above and below the plane. Giant molecular clouds, the birthplace of stars, also have low mean velocities and thus are confined to regions relatively close to the galactic plane. The disk rotates clockwise as viewed from "galactic north," at a relatively constant velocity of 160-220 km/sec. This motion is distinctly non-Keplerian, the result of the very nonspherical mass distribution. The rotation velocity for a circular galactic orbit in the galactic plane defines the Local Standard of Rest (LSR). The LSR is then used as the reference frame for describing local stellar dynamics. The Sun and the solar system are located approxi-mately 8.5 kpc from the galactic center, and 10-20 pc above the central plane of the galactic disk. The circular orbit velocity at the Sun's distance from the galactic center is 220 km/sec, and the Sun and the solar system are moving at approximately 17 to 22 km/sec relative to the LSR. -
Arxiv:1611.06573V2
Draft version April 5, 2017 Preprint typeset using LATEX style emulateapj v. 01/23/15 DYNAMICAL FRICTION AND THE EVOLUTION OF SUPERMASSIVE BLACK HOLE BINARIES: THE FINAL HUNDRED-PARSEC PROBLEM Fani Dosopoulou and Fabio Antonini Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astrophysics, Northwestern University, Evanston, IL 60208 Draft version April 5, 2017 ABSTRACT The supermassive black holes originally in the nuclei of two merging galaxies will form a binary in the remnant core. The early evolution of the massive binary is driven by dynamical friction before the binary becomes “hard” and eventually reaches coalescence through gravitational wave emission. We consider the dynamical friction evolution of massive binaries consisting of a secondary hole orbiting inside a stellar cusp dominated by a more massive central black hole. In our treatment we include the frictional force from stars moving faster than the inspiralling object which is neglected in the standard Chandrasekhar’s treatment. We show that the binary eccentricity increases if the stellar cusp density profile rises less steeply than ρ r−2. In cusps shallower than ρ r−1 the frictional timescale can become very long due to the∝ deficit of stars moving slower than∝ the massive body. Although including the fast stars increases the decay rate, low mass-ratio binaries (q . 10−3) in sufficiently massive galaxies have decay timescales longer than one Hubble time. During such minor mergers the secondary hole stalls on an eccentric orbit at a distance of order one tenth the influence radius of the primary hole (i.e., 10 100pc for massive ellipticals). -
Stellar Dynamics and Stellar Phenomena Near a Massive Black Hole
Stellar Dynamics and Stellar Phenomena Near A Massive Black Hole Tal Alexander Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 234 Herzl St, Rehovot, Israel 76100; email: [email protected] | Author's original version. To appear in Annual Review of Astronomy and Astrophysics. See final published version in ARA&A website: www.annualreviews.org/doi/10.1146/annurev-astro-091916-055306 Annu. Rev. Astron. Astrophys. 2017. Keywords 55:1{41 massive black holes, stellar kinematics, stellar dynamics, Galactic This article's doi: Center 10.1146/((please add article doi)) Copyright c 2017 by Annual Reviews. Abstract All rights reserved Most galactic nuclei harbor a massive black hole (MBH), whose birth and evolution are closely linked to those of its host galaxy. The unique conditions near the MBH: high velocity and density in the steep po- tential of a massive singular relativistic object, lead to unusual modes of stellar birth, evolution, dynamics and death. A complex network of dynamical mechanisms, operating on multiple timescales, deflect stars arXiv:1701.04762v1 [astro-ph.GA] 17 Jan 2017 to orbits that intercept the MBH. Such close encounters lead to ener- getic interactions with observable signatures and consequences for the evolution of the MBH and its stellar environment. Galactic nuclei are astrophysical laboratories that test and challenge our understanding of MBH formation, strong gravity, stellar dynamics, and stellar physics. I review from a theoretical perspective the wide range of stellar phe- nomena that occur near MBHs, focusing on the role of stellar dynamics near an isolated MBH in a relaxed stellar cusp. -
Two Stellar Components in the Halo of the Milky Way
1 Two stellar components in the halo of the Milky Way Daniela Carollo1,2,3,5, Timothy C. Beers2,3, Young Sun Lee2,3, Masashi Chiba4, John E. Norris5 , Ronald Wilhelm6, Thirupathi Sivarani2,3, Brian Marsteller2,3, Jeffrey A. Munn7, Coryn A. L. Bailer-Jones8, Paola Re Fiorentin8,9, & Donald G. York10,11 1INAF - Osservatorio Astronomico di Torino, 10025 Pino Torinese, Italy, 2Department of Physics & Astronomy, Center for the Study of Cosmic Evolution, 3Joint Institute for Nuclear Astrophysics, Michigan State University, E. Lansing, MI 48824, USA, 4Astronomical Institute, Tohoku University, Sendai 980-8578, Japan, 5Research School of Astronomy & Astrophysics, The Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Australian Capital Territory 2611, Australia, 6Department of Physics, Texas Tech University, Lubbock, TX 79409, USA, 7US Naval Observatory, P.O. Box 1149, Flagstaff, AZ 86002, USA, 8Max-Planck-Institute für Astronomy, Königstuhl 17, D-69117, Heidelberg, Germany, 9Department of Physics, University of Ljubljana, Jadronska 19, 1000, Ljubljana, Slovenia, 10Department of Astronomy and Astrophysics, Center, 11The Enrico Fermi Institute, University of Chicago, Chicago, IL, 60637, USA The halo of the Milky Way provides unique elemental abundance and kinematic information on the first objects to form in the Universe, which can be used to tightly constrain models of galaxy formation and evolution. Although the halo was once considered a single component, evidence for is dichotomy has slowly emerged in recent years from inspection of small samples of halo objects. Here we show that the halo is indeed clearly divisible into two broadly overlapping structural components -- an inner and an outer halo – that exhibit different spatial density profiles, stellar orbits and stellar metallicities (abundances of elements heavier than helium). -
Near-Field Cosmology with Extremely Metal-Poor Stars
AA53CH16-Frebel ARI 29 July 2015 12:54 Near-Field Cosmology with Extremely Metal-Poor Stars Anna Frebel1 and John E. Norris2 1Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; email: [email protected] 2Research School of Astronomy & Astrophysics, The Australian National University, Mount Stromlo Observatory, Weston, Australian Capital Territory 2611, Australia; email: [email protected] Annu. Rev. Astron. Astrophys. 2015. 53:631–88 Keywords The Annual Review of Astronomy and Astrophysics is stellar abundances, stellar evolution, stellar populations, Population II, online at astro.annualreviews.org Galactic halo, metal-poor stars, carbon-enhanced metal-poor stars, dwarf This article’s doi: galaxies, Population III, first stars, galaxy formation, early Universe, 10.1146/annurev-astro-082214-122423 cosmology Copyright c 2015 by Annual Reviews. All rights reserved Abstract The oldest, most metal-poor stars in the Galactic halo and satellite dwarf galaxies present an opportunity to explore the chemical and physical condi- tions of the earliest star-forming environments in the Universe. We review Access provided by California Institute of Technology on 01/11/17. For personal use only. the fields of stellar archaeology and dwarf galaxy archaeology by examin- Annu. Rev. Astron. Astrophys. 2015.53:631-688. Downloaded from www.annualreviews.org ing the chemical abundance measurements of various elements in extremely metal-poor stars. Focus on the carbon-rich and carbon-normal halo star populations illustrates how these provide insight into the Population III star progenitors responsible for the first metal enrichment events. We extend the discussion to near-field cosmology, which is concerned with the forma- tion of the first stars and galaxies, and how metal-poor stars can be used to constrain these processes. -
Galaxies at High Z II
Physical properties of galaxies at high redshifts II Different galaxies at high z’s 11 Luminous Infra Red Galaxies (LIRGs): LFIR > 10 L⊙ 12 Ultra Luminous Infra Red Galaxies (ULIRGs): LFIR > 10 L⊙ 13 −1 SubMillimeter-selected Galaxies (SMGs): LFIR > 10 L⊙ SFR ≳ 1000 M⊙ yr –6 −3 number density (2-6) × 10 Mpc The typical gas consumption timescales (2-4) × 107 yr VIGOROUS STAR FORMATION WITH LOW EFFICIENCY IN MASSIVE DISK GALAXIES AT z =1.5 Daddi et al 2008, ApJ 673, L21 The main question: how quickly the gas is consumed in galaxies at high redshifts. Observations maybe biased to galaxies with very high star formation rates. and thus give a bit biased picture. Motivation: observe galaxies in CO and FIR. Flux in CO is related with abundance of molecular gas. Flux in FIR gives SFR. So, the combination gives the rate of gas consumption. From Rings to Bulges: Evidence for Rapid Secular Galaxy Evolution at z ~ 2 from Integral Field Spectroscopy in the SINS Survey " Genzel et al 2008, ApJ 687, 59 We present Hα integral field spectroscopy of well-resolved, UV/optically selected z~2 star-forming galaxies as part of the SINS survey with SINFONI on the ESO VLT. " " Our laser guide star adaptive optics and good seeing data show the presence of turbulent rotating star- forming outer rings/disks, plus central bulge/inner disk components, whose mass fractions relative to the total dynamical mass appear to scale with the [N II]/H! flux ratio and the star formation age. " " We propose that the buildup of the central disks and bulges of massive galaxies at z~2 can be driven by the early secular evolution of gas-rich proto-disks. -
Astr-Astronomy 1
ASTR-ASTRONOMY 1 ASTR 1116. Introduction to Astronomy Lab, Special ASTR-ASTRONOMY 1 Credit (1) This lab-only listing exists only for students who may have transferred to ASTR 1115G. Introduction Astro (lec+lab) NMSU having taken a lecture-only introductory astronomy class, to allow 4 Credits (3+2P) them to complete the lab requirement to fulfill the general education This course surveys observations, theories, and methods of modern requirement. Consent of Instructor required. , at some other institution). astronomy. The course is predominantly for non-science majors, aiming Restricted to Las Cruces campus only. to provide a conceptual understanding of the universe and the basic Prerequisite(s): Must have passed Introduction to Astronomy lecture- physics that governs it. Due to the broad coverage of this course, the only. specific topics and concepts treated may vary. Commonly presented Learning Outcomes subjects include the general movements of the sky and history of 1. Course is used to complete lab portion only of ASTR 1115G or ASTR astronomy, followed by an introduction to basic physics concepts like 112 Newton’s and Kepler’s laws of motion. The course may also provide 2. Learning outcomes are the same as those for the lab portion of the modern details and facts about celestial bodies in our solar system, as respective course. well as differentiation between them – Terrestrial and Jovian planets, exoplanets, the practical meaning of “dwarf planets”, asteroids, comets, ASTR 1120G. The Planets and Kuiper Belt and Trans-Neptunian Objects. Beyond this we may study 4 Credits (3+2P) stars and galaxies, star clusters, nebulae, black holes, and clusters of Comparative study of the planets, moons, comets, and asteroids which galaxies. -
Dwarf Galaxies 1 Planck “Merger Tree” Hierarchical Structure Formation
04.04.2019 Grebel: Dwarf Galaxies 1 Planck “Merger Tree” Hierarchical Structure Formation q Larger structures form q through successive Illustris q mergers of smaller simulation q structures. q If baryons are Time q involved: Observable q signatures of past merger q events may be retained. ➙ Dwarf galaxies as building blocks of massive galaxies. Potentially traceable; esp. in galactic halos. Fundamental scenario: q Surviving dwarfs: Fossils of galaxy formation q and evolution. Large structures form through numerous mergers of smaller ones. 04.04.2019 Grebel: Dwarf Galaxies 2 Satellite Disruption and Accretion Satellite disruption: q may lead to tidal q stripping (up to 90% q of the satellite’s original q stellar mass may be lost, q but remnant may survive), or q to complete disruption and q ultimately satellite accretion. Harding q More massive satellites experience Stellar tidal streams r r q higher dynamical friction dV M ρ V from different dwarf ∝ − r 3 galaxy accretion q and sink more rapidly. dt V events lead to ➙ Due to the mass-metallicity relation, expect a highly sub- q more metal-rich stars to end up at smaller radii. structured halo. 04.04.2019 € Grebel: Dwarf Galaxies Johnston 3 De Lucia & Helmi 2008; Cooper et al. 2010 accreted stars (ex situ) in-situ stars Stellar Halo Origins q Stellar halos composed in part of q accreted stars and in part of stars q formed in situ. Rodriguez- q Halos grow from “from inside out”. Gomez et al. 2016 q Wide variety of satellite accretion histories from smooth growth to discrete events. -
Astro2020 Science White Paper the Multidimensional Milky Way
Astro2020 Science White Paper The Multidimensional Milky Way Thematic Areas: Planetary Systems Star and Planet Formation Formation and Evolution of Compact Objects 3Cosmology and Fundamental Physics 3Stars and Stellar Evolution 3Resolved Stellar Populations and their Environments 3Galaxy Evolution Multi-Messenger Astronomy and Astrophysics Principal Author: Name: Robyn Sanderson Institution: University of Pennsylvania / Flatiron Institute Email: [email protected] Co-authors (affiliations after text): Jeffrey L. Carlin1, Emily C. Cunningham2, Nicolas Garavito-Camargo3, Puragra Guhathakurta2, Kathryn V. Johnston4,5, Chervin F. P. Laporte6, Ting S. Li7,8, S. Tony Sohn9 Endorsers (affiliations after text): From the WFIRST Astrometry Working Group: Jay Anderson9, Andrea Bellini9, David P. Bennett10, Stefano Casertano9, S. Michael Fall9, Mattia Libralato9, Sangeeta Malhotra10, Leonidas A. Moustakas11, Jason Rhodes11 Other Endorsers: Lee Armus12, Yumi Choi13,14, Andres del Pino9, Elena D’Onghia15, Mark Fardal9, Karoline M. Gilbert9, Carl J. Grillmair12, Nitya Kallivayalil16, Evan N. Kirby17, Jing Li18, Jennifer L. Marshall19, Adrian M. Price-Whelan20, Elena Sacchi9, David N. Spergel5,20, Monica Valluri21, Roeland P. van der Marel9 Abstract: Studying our Galaxy, the Milky Way (MW), gives us a close-up view of the inter- play between cosmology, dark matter, and galaxy formation. In the next decade our under- standing of the MW’s dynamics, stellar populations, and structure will undergo a revolution thanks to planned and proposed astrometric, spectroscopic and photometric surveys, build- ing on recent advances by the Gaia astrometric survey. Together, these new efforts will mea- sure three-dimensional positions and velocities and numerous chemical abundances for stars arXiv:1903.07641v1 [astro-ph.GA] 18 Mar 2019 to the MW’s edge and well into the Local Group, leading to a complete multidimensional view of our Galaxy. -
Systematic Motions in the Galactic Plane Found in the Hipparcos
Astronomy & Astrophysics manuscript no. cabad0609 September 30, 2018 (DOI: will be inserted by hand later) Systematic motions in the galactic plane found in the Hipparcos Catalogue using Herschel’s Method Carlos Abad1,2 & Katherine Vieira1,3 (1) Centro de Investigaciones de Astronom´ıa CIDA, 5101-A M´erida, Venezuela e-mail: [email protected] (2) Grupo de Mec´anica Espacial, Depto. de F´ısica Te´orica, Universidad de Zaragoza. 50006 Zaragoza, Espa˜na (3) Department of Astronomy, Yale University, P.O. Box 208101 New Haven, CT 06520-8101, USA e-mail: [email protected] September 30, 2018 Abstract. Two motions in the galactic plane have been detected and characterized, based on the determination of a common systematic component in Hipparcos catalogue proper motions. The procedure is based only on positions, proper motions and parallaxes, plus a special algorithm which is able to reveal systematic trends. Our results come o o o o from two stellar samples. Sample 1 has 4566 stars and defines a motion of apex (l,b) = (177 8, 3 7) ± (1 5, 1 0) and space velocity V = 27 ± 1 km/s. Sample 2 has 4083 stars and defines a motion of apex (l,b)=(5o4, −0o6) ± o o (1 9, 1 1) and space velocity V = 32 ± 2 km/s. Both groups are distributed all over the sky and cover a large variety of spectral types, which means that they do not belong to a specific stellar population. Herschel’s method is used to define the initial samples of stars and later to compute the common space velocity. -
Evolution of a Dissipative Self-Gravitating Particle Disk Or Terrestrial Planet Formation Eiichiro Kokubo
Evolution of a Dissipative Self-Gravitating Particle Disk or Terrestrial Planet Formation Eiichiro Kokubo National Astronomical Observatory of Japan Outline Sakagami-san and Me Planetesimal Dynamics • Viscous stirring • Dynamical friction • Orbital repulsion Planetesimal Accretion • Runaway growth of planetesimals • Oligarchic growth of protoplanets • Giant impacts Introduction Terrestrial Planets Planets core (Fe/Ni) • Mercury, Venus, Earth, Mars Alias • rocky planets Orbital Radius • ≃ 0.4-1.5 AU (inner solar system) Mass • ∼ 0.1-1 M⊕ Composition • rock (mantle), iron (core) mantle (silicate) Close-in super-Earths are most common! Semimajor Axis-Mass Semimajor Axis–Mass “two mass populations” Orbital Elements Semimajor Axis–Eccentricity (•), Inclination (◦) “nearly circular coplanar” Terrestrial Planet Formation Protoplanetary disk Gas/Dust 6 10 yr Planetesimals ..................................................................... ..................................................................... 5-6 10 yr Protoplanets 7-8 10 yr Terrestrial planets Act 1 Dust to planetesimals (gravitational instability/binary coagulation) Act 2 Planetesimals to protoplanets (runaway-oligarchic growth) Act 3 Protoplanets to terrestrial planets (giant impacts) Planetesimal Disks Disk Properties • many-body (particulate) system • rotation • self-gravity • dissipation (collisions and accretion) Planet Formation as Disk Evolution • evolution of a dissipative self-gravitating particulate disk • velocity and spatial evolution ↔ mass evolution Question How -
ASTRON 449: Stellar Dynamics Winter 2017 in This Course, We Will Cover
ASTRON 449: Stellar Dynamics Winter 2017 In this course, we will cover • the basic phenomenology of galaxies (including dark matter halos, stars clusters, nuclear black holes) • theoretical tools for research on galaxies: potential theory, orbit integration, statistical description of stellar systems, stability of stellar systems, disk dynamics, interactions of stellar systems • numerical methods for N-body simulations • time permitting: kinetic theory, basics of galaxy formation Galaxy phenomenology Reading: BT2, chap. 1 intro and section 1.1 What is a galaxy? The Milky Way disk of stars, dust, and gas ~1011 stars 8 kpc 1 pc≈3 lyr Sun 6 4×10 Msun black hole Gravity turns gas into stars (all in a halo of dark matter) Galaxies are the building blocks of the Universe Hubble Space Telescope Ultra-Deep Field Luminosity and mass functions MW is L* galaxy Optical dwarfs Near UV Schechter fits: M = 2.5 log L + const. − 10 Local galaxies from SDSS; Blanton & Moustakas 08 Hubble’s morphological classes bulge or spheroidal component “late type" “early type" barred http://skyserver.sdss.org/dr1/en/proj/advanced/galaxies/tuningfork.asp Not a time or physical sequence Galaxy rotation curves: evidence for dark matter M33 rotation curve from http://en.wikipedia.org/wiki/Galaxy_rotation_curve Galaxy clusters lensing arcs Abell 1689 ‣ most massive gravitational bound objects in the Universe ‣ contain up to thousands of galaxies ‣ most baryons intracluster gas, T~107-108 K gas ‣ smaller collections of bound galaxies are called 'groups' Bullet cluster: more