Turn Right At Orion

by Mitchell Begelman

  special theory of relativity: Einstein’s 1905 theory describing the relationships among space, time, and motion, but neglecting gravity. Gravitational effects are treated in Einstein’s general theory of relativity (1915).

  spiral arms: curved patterns superimposed on the disk of a spiral galaxy, corresponding to “traffic jams” in the orbital flow of stars and gas. Associated with the accumulation of large molecular clouds and regions of star formation.

  spiral galaxy: galaxy containing a prominent disk of stars and gas embedded in an extended halo. Gravitational disturbances within the disk give rise to spiral arms.

  SS 433: binary system notable for producing a pair of jets that precess about a fixed axis, like a wobbling top. The jets are believed to arise near the center of an accretion disk, but it is not known whether the accreting body is a neutron star or a black hole.

  superbubble: large region of hot interstellar gas created by the combined action of stellar winds and supernovae from many hot stars.

  supernova: enormous explosion of a stellar envelope that occurs when a massive star’s core collapses to form a neutron star. This term also refers to explosions of white dwarfs that have grown too heavy to support themselves.

  synchrotron radiation: radiation produced when electrons moving at close to the speed of light gyrate in a magnetic field.

  Tarantula Nebula: huge star-forming region in the Large Magellanic Cloud. Thousands of times more luminous than Orion. Site of the fictional supernova explosion (based on the real Supernova 1987A) witnessed by the narrator.

  Texas Symposium: biennial series of conferences, first held in Dallas in 1963, focusing on the latest results in relativistic astrophysics. The meeting site now rotates among international destinations, returning to Texas only occasionally.

  tidal force: differential gravitational force that can stretch or squeeze objects.

  Trapezium: quartet of young, massive stars responsible for illuminating the Orion Nebula.

  Virgo Cluster: cluster of more than a thousand galaxies located about 60 million light-years from the Milky Way.

  white dwarf: body with a mass similar to that of the Sun but a size similar to that of Earth. Supported against gravity by electron degeneracy pressure.

  Index

  Accretion disks; definition; jets and; plasma and; protostars and; of SS 433; See also Disks

  Accretion streams

  Aging

  Alcohol in molecular clouds

  Ammonia in dust disks

  Andromeda (spiral galaxy)

  Angular momentum; black holes and; Milky Way halo and

  Antares

  Asteroid impact with sheperd planets

  Atomic hydrogen

  Atoms; the aurora borealis and; electron clouds and; filaments of Crab II and; in gap between molecular clouds and Trapezium stars; hydrogen; hydrogen in interstellar clouds; hydrogen in molecular clouds; jets of SS 433 and; neutron stars and; in Orion Nebula molecular clouds; planetary nebulae; the Sun and; Trapezium stars and; See also Molecules; Particles

  Aurora borealis, the

  Barnard’s Loop

  Betelgeuse (red supergiant); in comparison to the Sun; core of; distance from Earth; helium and; surface of; winds of

  Binary systems: Cygnus X–1; planets and; SS 433

  Black holes; of Cygnus X–1, ; definition; gravitational fields and; growth of; jets and; luminosity and; of M87; of the Milky Way; neutron stars and; stellar velocities and

  Blueshift

  Blue supergiants; temperature and; See also Supernova 1987A

  BN-KL Cluster (stellar)

  Bulges: definition; of merging stars; of Milky Way, of SS

  Calcium; Supernova 1987A and

  Carbon; atomic weight; bulge of the Milky Way and; incipient to supernovae; versus neutrinos; in Orion Nebula molecular clouds; planetary nebulae and; and red supergiant at Dumbbell Nebula’s center; Supernova 1987A and

  Carbon dioxide

  Carbon monoxide; in molecular clouds

  Clouds (electron)

  Clouds (hydrogen): the Magellanic Stream; in the Milky Way disk, in the Milky Way halo; in the Virgo Cluster

  Clouds (interstellar); definition; in M87; See also Gas; Molecular clouds

  Clusters (galactic); dominant galaxies of; See also Virgo Cluster

  Clusters (stellar): globular; near Trapezium Cluster; tracers and; See also Trapezium Cluster

  Coal versus hydrogen

  Cobalt in Supernova 1987A

  Color: at the corona of the Milky Way black hole; disk of Cygnus X–1 and; Dumbbell Nebula and; dust and; filaments of Crab II; of gas in outer layers of Orion Nebula molecular clouds; hot stars; in M87; planetary nebulae and; of radiation at black holes; spectral lines; Supernova 1987A and

  Coma Bernices

  Comets and evolution

  Copernican Principle; definition

  Cores (stellar): of Betelgeuse; mass and; of massive stars incipient to supernovae; of neutron star created by Supernova 1987A; nuclear reactions and; of red giants; of red supergiant at Dumbbell Nebula’s center; rotation and

  Cosmic rays

  Crab Nebula; glossary description

  Crab II (imaginary Crab Nebula); nebula of, neutron star of; See also Pulsars

  Cygnus X–1 (binary system)

  Debris: from Crab II supernova; in the Solar System; SS 433 and; from Supernova 1987A and; See also Dust; Dust disks

  Degeneracy; definition; electron clouds and; and massive stars incipient to supernovae; versus neutrons; white dwarfs and

  Deneb

  Densities: of galaxies in the Local Group; of galaxies in the Virgo Cluster; iron and Supernova 1987A; of M87 black hole; of Milky Way black hole; of neutrinos incipient to Supernova 1987A; neutron star of Crab Nebula; of neutron stars; nickel and Supernova 1987A and; surfaces of neutron stars and

  Disks (of binary systems): Cygnus X–1; SS 433

  Disks (galactic): orbital motions and; spiral arms and; stability and; in the Virgo Cluster; See also Accretion, disks

  Disks (planetary)

  Disks (protostellar)

  Disks (stellar): as debris from star formation; planet formation and; See also Dust disks; Planet formation

  Distances: Betelgeuse from Earth; Betelgeuse from Trapezium; and brightness of Trapezium stars; center of Milky Way from Earth; Crab Nebula from SS 433; Cygnus X–1 from center of Milky Way; and density of neutrinos incipient to Supernova 1987A; expansion of Supernova 1987A; of gap between molecular clouds and Trapezium stars; horizon of black holes and; interstellar dust and visibility; orbit of instability for Cygnus X–1 black hole; orbit of instability for Milky Way black hole; Orion Nebula from Earth; radiance of Crab II pulsar and; size of black hole of Cygnus, X–1 and; size of Crab 11 neutron star; size of Crab Nebula neutron star; size of horizon of Cygnus X–1 black hole; size of horizon of Milky Way black hole; size of molecular clouds in the Milky Way; size of the Virgo Cluster; SS 433 from Earth; thickness off Milky Way disk; Virago Cluster from Large Magellanic Cloud; Virgo Cluster from Milky Way

  Doppler shift

  “Dream, or Lunar Astronomy” (Kepler)

  Dumbbell Nebula (planetary); distance from Earth; glossary description; red supergiant at the center of

  Dust (interstellar): creation of stars in Orion Nebula and; definition; estimating distances to stars and; in gap between molecular clouds and Trapezium stars; light rays and; mixed with Orion Nebula molecular clouds; spacecraft and; Supernova 1987A and; in vicinity of the Sun; See also Debris

  Dust disks; binary stars and planet formation. and; as debris from star formation; gaps in during planet formation; ice in during planet formation; in planet formation

  Earth; comets and; electrical repulsion and; formation of the moon and

  Einstein, Albert

  Electrical currents and magnetic fields

  Electrical repulsion versus gravity

  Electromagnetic radiation at the corona of the Milky Way black hole; See also
Radiation

  Electron clouds

  Electrons: color and photons and; at the corona of the Milky Way black hole; Crab II neutron star and; Crab Nebula and; degeneracy and; in gap between molecular clouds and Trapezium stars; incipient to supernovae; ions and; magnetic fields and; and magnetic fields in star formation; in M87; neutron stars and; in Orion Nebula molecular clouds; and planetary nebulae; plasma and; spacecraft and; spectral lines and; Supernova 1987A and; surfaces of neutron stars and; synchrotron radiation and; Trapezium stars and; in vicinity of the Sun

  Elliptical galaxies; definition; in the Virgo Cluster; See also M49; M87

  Energy; black hole of Cygnus X–1 and; brightness of stars and; at the corona of the Milky Way black hole; Crab II pulsar and; at the horizon of the Milky Way black hole; motion and; quantum mechanics and; radioactive cobalt and Supernova 1987A and; red giants and; shrinkage of red giants and; the Sun’s radiance and; supergiants and; synchrotron radiation and

  Equilibrium; Earth and; gravity and; Milky Way halo and; neutrons stars and

  Explosion: of neutron star of Crab Nebula; See also Supernova 1987A

  Filaments: of Crab II; in M87; Supernova 1987A and

  Formaldehyde in molecular clouds

  Friction in accretion disks

  Galaxies: black holes and; gravitational fields and; hierarchical structure of; in the Virgo Cluster; See also Elliptical galaxies; Magellanic Clouds, the; Spiral galaxies

  Gamma rays; Crab II neutron star and; jets of SS 433 and; Supernova 1987A and

  Gas, gas clouds; accretion disks and; at black hole of M87; at the corona of the Milky Way black hole; Crab II and; degeneracy and; disk of Cygnus X–1 and; Dumbbell nebula and; dust disks and; formation of stars near Trapezium Cluster and; in gap between molecular clouds and Trapezium stars; helium; interstellar clouds and; jets of SS 433 and; the Magellanic Clouds and; orbital motions and; planetary nebulae and; plasma and; Ring Nebula and; shell of Crab Nebula and; spiral arms and; stellar bars and; superbubbles and; Trapezium cluster and; at various distances from center of M87; in vicinity of the Sun; in the Virgo Cluster; See also Nebulae; plasma

  Gas streams; companion star of Cygnus X–1 and; companion star of SS 433 and; disk of Cygnus X–1 and; gas knots in Orion Nebula; See also Jets

  General theory of relativity

  Globular clusters

  Gold, Tommy

  Gould, Benjamin

  Gould’s Belt

  Graphite in Supernova 1987A

  Gravitational fields: accretion disks and; black holes and; energy and; of galaxies; and light rays at block hole of Cygnus, X–1; Milky Way black hole and; of neutron stars; in the Virgo Cluster; See also Black holes

  Gravity; acceleration and; black holes and; in concretion of protoplanets; condensation, of matter toward a common center and; Crab II neutron star and; creation of jets and; versus electrical repulsion; galactic disks and; in general theory of relativity; incipient to supernovae; luminosity and; the Magellanic Stream and; merging stars and; Milky Way halo and; motion and; motion of dust in planet formation and; neutrons stars and; red giants and; and red supergiant at Dumbbell Nebula’s center; shrinkage of red giants and; spiral arms and; Spiral structure of galaxies and; star formation and; stellar bars and; stellar disks and; surfaces of neutron stars and; in the Virgo Cluster; white dwarfs and; versus winds from bulge of SS 433

  Halos; definition; pervading clusters of galaxies in the Virgo Cluster

  Halos (galactic): matter and; orbital motions and; in the Virgo Cluster

  “Headlight effect,”

  Heartbeat

  Heat: black holes and; versus condensation of matter toward a common center; energy and; filaments of Crab II and; shrinkage of red giants and; spacecraft and; See also Temperature

  Helium; cores of stars and; dust disks and; filaments of Crab II and; fueling of the Sun and; incipient to supernovae; planetary nebulae; red giants and; and red supergiant at Dumbbell Nebula’s center; Ring Nebula and; SS 433 and; Supernova 1987A and; Trapezium stars and

  Herschel, William

  Horizon; of Cygnus X–1 black hole; definition

  Hot stars: definition; superbubbles and; See also Trapezium Cluster

  Hydrogen; atomic; cores of stars and; Dumbbell Nebula and; dust disks and; filaments of Crab II and; fueling of the Sun and; in gap between molecular clouds and Trapezium stars; hot stars and; incipient to supernovae; interstellar clouds and; the Magellanic Stream; in M87; molecular clouds and; red giants and; and red supergiant at Dumbbell Nebula’s center; spacecraft and; SS 433 and; Supernova 1987A and; Trapezium stars and; in vicinity of the Sun; See also Clouds (hydrogen)

  Ice in dust disks

  Ions: definition; and magnetic fields in star formation; in Orion Nebula molecular clouds; planetary nebulae; plasma and; spacecraft and

  Iron; bulge of the Milky Way and; incipient to supernovae; the Magellanic Clouds and; Supernova 1987 A and; Trapezium stars and; white dwarfs and

  jets (plasmic); condensation of matter toward a common center and; definition; of M87 and; from protostar in Orion Nebula; See also Gas streams; Plasma; SS 433

  Jupiter

  Kapteyn, Johannes

  Kepler, Johannes

  Lagoon Nebula

  Large Mangellanic Cloud; in relation to Small Magellanic Cloud; Supernova 1987A and; See also Tarantula Nebula

  Light, light rays; of Betelgeuse; black hole of Cygnus X–1 and; black holes and; Crab II neutron star and; debris in the Solar System and; in gap between molecular clouds and Trapezium stars; “headlight effect,”; photons and; polarized; and red supergiant at Dumbbell Nebula’s center; Supernova 1987A and; synchrotron radiation and; See also Luminosity; Speed of Light

  Lithium

  Local Group, the; definition

  Luminosity: black hole of Cygnus X–1 and; of blue supergiant Supernova 1987A; of Crab II pulsar; gravity and; shrinkage of red giants and; of Trapezium stars; See also Light

  Magellanic Clouds, the; glossary description; the Milky Way and; See also Large Magellanic Cloud; Small Magellanic Cloud

  Magellanic Stream, the

  Magnesium: incipient to supernovae; Supernova 1987A and

  Magnetic fields; black holes and; condensation of matter toward a common center and; Crab II neutron star and; energy and; and gas knots in star formation; in M87; particles and; plasma and; rotation of protostellar disk and; synchrotron radiation and

  Mars

  Mass: of Betelgeuse; black hole of Cygnus X–1 and; brightness of stars and; of Crab II neutron star; Crab Nebula and; creation of jets and; of Milky Way black hole; in the Virgo Cluster

  Matter: black hole of Cygnus X–1 and; black hole of M87 and; black holes and; companion star of SS 433 and; Crab II neutron star and; disk of Cygnus X–1 and; elements in planets versus the rest of space; filaments of Crab II and; galactic halos and; gas in M87 and; jets of M87; jets of SS 433; Milky Way halo and; orbital motions and; Orion Nebula v. planetary nebulae; quantum mechanics and; star formation and; in the Virgo cluster; the winds of stars and

  M87 (elliptical galaxy); black hole of; gas at black hole of; gas at various distances from center; globular cluster; glossary description; jets of

  Messier, Charles

  Methane in dust disks

  M49 (elliptical galaxy)

  Microwaves

  Milky Way, center of; atmospheric pressure; black hole; cavity of; distance from Earth; gas and; infrared radiation from; Sun’s orbit around

  Milky Way, disk of; interstellar dust and; stability and

  Milky Way, halo of; angular momentum and; equilibrium and; the Magellanic Clouds and; matter and

  Milky Way (spiral galaxy); cavity of; gas to dust ratio; globular clusters; the Magellanic Clouds and

  Molecular clouds; definition, in the Milky Way disk; in the Orion Nebula; spiral arms and; star formation and; star formation near the Trapezium Cluster and; tracers and; the Trapezium Cluster and; in the Virgo Cluster; See also Clouds

>   Molecules: hydrogen atoms in molecular clouds; hydrogen in molecular clouds; See also Atoms

  Moons in gaps of planetary rings

  Motion: black holes and; caused by gravity of Cygnus X–1 black hole; versus collapse of supergiant at Dumbbell Nebula’s center: creation of jets and; degeneracy and; of dust in planet formation; energy and; filaments of Crab II and; gas at black hole of M87 and; versus gravity; gravity and; See also Angular momentum

  Nebulae (planetary); absence of accretion disks and; Ring Nebula; versus stellar nebulae; See also Dumbbell Nebula; Gas

  Nebulae (stellar): definition; versus planetary nebulae; See also Crab Nebula; Gas; Orion Nebula

  Neon; incipient to supernovae; and red supergiant at Dumbbell Nebula’s center, Supernova 1987A and; Trapezium stars and

  Neutrinos incipient to supernovae

  Neutrons; degeneracy and; jets of SS 433 and; neutron stars and

  Neutron stars; black holes and; Crab II and; Crab Nebula and; definition; degeneracy and; density of matter and; equilibrium and; luminosity and; preservation from collapse; supernovae and

  Nickel in Supernova 1987A

  Nitrogen: Dumbbell Nebula and; in Earth’s atmosphere; planetary nebulae and; and red supergiant at Dumbbell Nebula’s center; Supernova 1987A and

  Novae and interstellar dust

  Nuclear reactions; cores of stars and; helium and; incipient to supernovae; and red supergiant at Dumbbell Nebula’s center; the Sun and; temperature and; white dwarfs and