DOCSLIB.ORG

Features of the Sky

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Features of the Sky 2 Principal Features of the Sky 2.1. Star Patterns: Asterisms the absence of stars, the “dark constellations.”2 Chinese con- stellations were different from and far more numerous than and Constellations were those of the Mediterranean area. As far as we are aware, the oldest extant Chinese star chart on paper is con- 2.1.1. Stellar Pattern Recognition tained in a 10th-century manuscript from Dunhuang, but there is far older evidence for sky charting from this area of About 15,000 stars are detectable by the human eye, most the world (see §10 and §2.2.3); a compilation by Chhien Lu- of them near the limit of visibility. At any one time, we may Chih listed 284 constellations containing a total of 1464 stars be able to see a few thousand stars in a dark sky, but we tend and is said to be based on a Han catalogue (see §10.1.2.3; to remember only striking patterns of them—asterisms and Yi, Kistemaker, and Yang (1986) for new maps and a such as the Big Dipper or whole constellations such as Ursa review of historical Chinese star catalogues). Major (the Big Bear) or Orion (the name of a mythological Western constellations in current use largely derive from hunter)—and so it has been for millennia. Today, the entire ancient Mediterranean sources, mainly the Near East and sky has been divided into constellations; they are not defined Greece, as we show in §7. The earliest surviving detailed according to appearance alone but according to location, description of the Greek constellations is in the poem and there are no boundary disputes. The modern names and Phaenomena by the Greek poet Aratos (Aratus in the locations are more or less those of Argelander (1799–1875) Roman sources), ~250 b.c. (Whitfield 1995, p. 23). The con- for the Northern Hemisphere and John Herschel stellations portrayed in the poem derive from a work also (1824–1896) for the Southern, but the present divisions of called Phaenomena, which has not survived, by the Greek the constellations1 were adopted by the International Astro- astronomer Eudoxos (or Eudoxus) (4th century b.c.). One nomical Union (IAU), the chief authority on such matters of the later sources that discusses this work is that of the sole as astronomical nomenclature, in 1930. The IAU has estab- remaining manuscript of Hipparchos (~150 b.c.), one of the lished 88 constellations in the sky; many reflecting an ancient greatest astronomers of antiquity. Many of the constellations heritage. can be seen as raised images on the Farnese Globe, the The names of the constellations recognized in antiquity oldest extant celestial globe, dated to the 2nd century b.c., were based on but representing a copy of an older work. Aratos mentioned • Mythological figures 47 constellations, whereas Claudius Ptolemy (~150 a.d.), • Animals or inanimate objects as perceived in the sky the source of much of our knowledge about Hipparchos, • Geographical or political analogues referred to 48 in the major astronomical work that we know • Associations with seasonal phenomena, or some other today as the Almagest. basis In ancient Greek usage, the constellations were the figures. For example, in the constellation of Cassiopeia, As we will show in later chapters, non-Western traditions the star z Cassiopeiae (abbreviated z Cas) is described as have perceived a rich variety of star patterns; some include “the star on the head”; a Cas, as “the star in the breast”; and 1 Boundaries are along coordinates of right ascension and declination referred to the equinox of 1875.0. See sections below for explanations of these terms. 2 See §14.2.5, for a Peruvian example. D.H. Kelley, E.F. Milone, Exploring Ancient Skies, DOI 10.1007/978-1-4419-7624-6_2, © Springer Science+Business Media, LLC 2011 9 10 2. Principal Features of the Sky h Cas as “the star over the throne, just over the thighs.” In constellation of Ursa Minor, the Little Bear, and the Perseus, the variable star Algol (b Per) is described as the Pleiades is a well-known asterism in the constellation “bright one” in the “Gorgon’s head.” Not all naked eye stars Taurus, the Bull. An exception is the Summer Triangle, com- fitted neatly into these groupings, so many stars were posed of the bright stars Vega, Deneb, and Altair in the con- omitted from the constellations. Those outside the accepted stellations Lyra, Cygnus, and Aquila, respectively. Even a figures were referred to as “unformed” (amórfwtoi; our single star may constitute an asterism. The star Spica, for word “amorphous” derives from a related word), or “scat- example, the brightest star in the constellation of Virgo, has tered” (spordeV, related to the Greek word for seed, been envisaged as a spike of wheat. spor, broadcast during sowing, and our cognate word, Modern common names of naked eye stars, derive from “sporadic”). The IAU reorganization created constellation European and Arabic usage, as well as proper names devised “homes” for these “unformed” stars. by Johann Bayer in 1603. The Bayer designations use lower- case Greek letters and, after these are exhausted, small Roman letters, to identify stars in a given constellation, for 2.1.2. Star Charts example, u Herculis or i Bootis. When these were exhausted, capital Roman letters were used. The lettered type of desig- The depictions of the Greco-Roman constellations as they nation was later extended to the Southern Hemisphere by were known in Ptolemy’s time (~150 a.d.) were preserved Nicolas Louis de Lacaille (1763) and John Herschel (1847). in Arabic sources, one of the best known being that of the The Greek letters are universally accepted, but an alterna- astronomer al-Sufı (10th century). R.H. Allen (1963) states tive designation to the Bayer letters for the fainter stars is that the sky representations of post-Renaissance Europe that of the Flamsteed numbers (Flamsteed 1725, Vol. 3), as, derive from those of Albrecht Dürer (1471–1528) of 1515 for example, 44 Bootis = i Bootis. Giuseppe Piazzi (1803) (Figure 1.1), in which the star positions from Ptolemy’s also published star catalogues in 1803 and 1814 (see catalogue were set down by another resident of Nürnberg Piazzi/Foderà Serio 1990). The Flamsteed numbers increase (Nuremberg), a mathematician named Heinvogel. The posi- with right ascension, a coordinate that increases from west tions were subsequently improved and more stars added, but to east (see §2.2.3). Many catalogues of stars and other the figures of Dürer essentially remained the same through objects use positional or sequence numbers, usually increas- the charts of Bayer (1603), Flamsteed (1729), and Arge- ing with right ascension. The best known star catalog of this lander (1843). More details about star charts from 1500 to kind is the Bright Star Catalog (Hoffleit 1982), which uses 1800 can be found in Warner (1979), and an even wider the positional sequence numbers of the Harvard Revised range of charts is found in Stott (1991/1995) and Whitfield Photometry Catalog (Pickering 1908); thus, BS 7001 = HR (1995). 7001 =aLyrae. The representations of the more obvious asterisms dif- Usually, the Greek letter designates the relative bright- fered widely from culture to culture. A familiar example is ness of the star within the constellation, but occasionally the Big Dipper, still known in England as the plough, and in they were assigned to a positional sequence, as in Ursa Germany and Scandinavia as the Wagen (wagon). In the Major. In the list of modern constellations, Table 2.1, the star Roman republic, it was the plow oxen. On many pre-19th- names are in Latin, with the historically earliest names refer- century maps and star charts, the term Septentrion or some ring to Latin forms of Greek originals. The columns contain variety of this term appears. The expression became syn- both nominative and possessive3 cases of the names, English onymous with the North, or northern regions, but originally equivalents, notable stars and other objects, and both meant the seven plow oxen. R.H. Allen (1963) says that the modern and ancient asterisms that are within the modern Big Dipper was known as a coffin in parts of the Mideast, boundaries. Only a few objects that cannot be seen unaided a wagon or bear in Greece, and a bull’s thigh in pre- under clear and dark sky circumstances are included. Hellenistic Egypt. Systematic attempts were made to “Double stars” are stars that appear close to each other rename the constellations at various times. Giordano Bruno in the sky; sometimes they are indeed physically close to (1548–1600) sought to invest the sky with figures represent- each other and interact gravitationally, but not always. The ing Moral Virtues. Julius Schiller of Augsburg produced the pair of stars Mizar and Alcor (z Ursae Majoris and 80 Ursae most widely known type of Bible-inspired charts in 1627. Majoris, respectively), in the handle of the Big Dipper, is an R.H. Allen’s (1963) encyclopedic search into the origins of example of a naked-eye double. star names and constellations reveals several other Euro- Types of “variable stars” are named after their prototypes, pean attempts to recast the constellations, although the such as delta Cephei or RR Lyrae. In the Bayer designations, various sources used by him are not always treated critically. no visible star had been assigned a letter later in the alpha- bet than Q; consequently, Argelander suggested that desig- 2.1.3. Modern Nomenclature nations of R and later would be used solely for variable stars. This scheme has been followed dogmatically to a logical Today, constellations refer to specified areas on the celestial conclusion ever since.
Load more

Recommended publications
  • Stsci Newsletter: 1997 Volume 014 Issue 01
    January 1997 • Volume 14, Number 1 SPACE TELESCOPE SCIENCE INSTITUTE Highlights of this issue: • AURA science and functional awards to Leitherer and Hanisch — pages 1 and 23 • Cycle 7 to be extended — page 5 • Cycle 7 approved Newsletter program listing — pages 7-13 Astronomy with HST Climbing the Starburst Distance Ladder C. Leitherer Massive stars are an important and powerful star formation events in sometimes dominant energy source for galaxies. Even the most luminous star- a galaxy. Their high luminosity, both in forming regions in our Galaxy are tiny light and mechanical energy, makes on a cosmic scale. They are not them detectable up to cosmological dominated by the properties of an distances. Stars ~100 times more entire population but by individual massive than the Sun are one million stars. Therefore stochastic effects times more luminous. Except for stars prevail. Extinction represents a severe of transient brightness, like novae and problem when a reliable census of the supernovae, hot, massive stars are Galactic high-mass star-formation the most luminous stellar objects in history is atempted, especially since the universe. massive stars belong to the extreme Massive stars are, however, Population I, with correspondingly extremely rare: The number of stars small vertical scale heights. Moreover, formed per unit mass interval is the proximity of Galactic regions — roughly proportional to the -2.35 although advantageous for detailed power of mass. We expect to find very studies of individual stars — makes it few massive stars compared to, say, difficult to obtain integrated properties, solar-type stars. This is consistent with such as total emission-line fluxes of observations in our solar neighbor- the ionized gas.
    [Show full text]
  • VU Research Portal
    VU Research Portal The impact of empire on market prices in Babylon Pirngruber, R. 2012 document version Publisher's PDF, also known as Version of record Link to publication in VU Research Portal citation for published version (APA) Pirngruber, R. (2012). The impact of empire on market prices in Babylon: in the Late Achaemenid and Seleucid periods, ca. 400 - 140 B.C. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. E-mail address: [email protected] Download date: 25. Sep. 2021 THE IMPACT OF EMPIRE ON MARKET PRICES IN BABYLON in the Late Achaemenid and Seleucid periods, ca. 400 – 140 B.C. R. Pirngruber VRIJE UNIVERSITEIT THE IMPACT OF EMPIRE ON MARKET PRICES IN BABYLON in the Late Achaemenid and Seleucid periods, ca. 400 – 140 B.C. ACADEMISCH PROEFSCHRIFT ter verkrijging van de graad Doctor aan de Vrije Universiteit Amsterdam, op gezag van de rector magnificus prof.dr.
    [Show full text]
  • A Hot Subdwarf-White Dwarf Super-Chandrasekhar Candidate
    A hot subdwarf–white dwarf super-Chandrasekhar candidate supernova Ia progenitor Ingrid Pelisoli1,2*, P. Neunteufel3, S. Geier1, T. Kupfer4,5, U. Heber6, A. Irrgang6, D. Schneider6, A. Bastian1, J. van Roestel7, V. Schaffenroth1, and B. N. Barlow8 1Institut fur¨ Physik und Astronomie, Universitat¨ Potsdam, Haus 28, Karl-Liebknecht-Str. 24/25, D-14476 Potsdam-Golm, Germany 2Department of Physics, University of Warwick, Coventry, CV4 7AL, UK 3Max Planck Institut fur¨ Astrophysik, Karl-Schwarzschild-Straße 1, 85748 Garching bei Munchen¨ 4Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106, USA 5Texas Tech University, Department of Physics & Astronomy, Box 41051, 79409, Lubbock, TX, USA 6Dr. Karl Remeis-Observatory & ECAP, Astronomical Institute, Friedrich-Alexander University Erlangen-Nuremberg (FAU), Sternwartstr. 7, 96049 Bamberg, Germany 7Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA 8Department of Physics and Astronomy, High Point University, High Point, NC 27268, USA *[email protected] ABSTRACT Supernova Ia are bright explosive events that can be used to estimate cosmological distances, allowing us to study the expansion of the Universe. They are understood to result from a thermonuclear detonation in a white dwarf that formed from the exhausted core of a star more massive than the Sun. However, the possible progenitor channels leading to an explosion are a long-standing debate, limiting the precision and accuracy of supernova Ia as distance indicators. Here we present HD 265435, a binary system with an orbital period of less than a hundred minutes, consisting of a white dwarf and a hot subdwarf — a stripped core-helium burning star.
    [Show full text]
  • Ix Ophiuchi: a High-Velocity Star Near a Molecular Cloud G
    The Astronomical Journal, 130:815–824, 2005 August # 2005. The American Astronomical Society. All rights reserved. Printed in U.S.A. IX OPHIUCHI: A HIGH-VELOCITY STAR NEAR A MOLECULAR CLOUD G. H. Herbig Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 Received 2005 March 24; accepted 2005 April 26 ABSTRACT The molecular cloud Barnard 59 is probably an outlier of the Upper Sco/ Oph complex. B59 contains several T Tauri stars (TTSs), but outside its northwestern edge are three other H -emission objects whose nature has been unclear: IX, KK, and V359 Oph. This paper is a discussion of all three and of a nearby Be star (HD 154851), based largely on Keck HIRES spectrograms obtained in 2004. KK Oph is a close (1B6) double. The brighter component is an HAeBe star, and the fainter is a K-type TTS. The complex BVR variations of the unresolved pair require both components to be variable. V359 Oph is a conventional TTS. Thus, these pre-main-sequence stars continue to be recognizable as such well outside the boundary of their parent cloud. IX Oph is quite different. Its absorption spec- trum is about type G, with many peculiarities: all lines are narrow but abnormally weak, with structures that depend on ion and excitation level and that vary in detail from month to month. It could be a spectroscopic binary of small amplitude. H and H are the only prominent emission lines. They are broad, with variable central reversals. How- ever, the most unusual characteristic of IX Oph is the very high (heliocentric) radial velocity: about À310 km sÀ1, common to all spectrograms, and very different from the radial velocity of B59, about À7kmsÀ1.
    [Show full text]
  • Naming the Extrasolar Planets
    Naming the extrasolar planets W. Lyra Max Planck Institute for Astronomy, K¨onigstuhl 17, 69177, Heidelberg, Germany [email protected] Abstract and OGLE-TR-182 b, which does not help educators convey the message that these planets are quite similar to Jupiter. Extrasolar planets are not named and are referred to only In stark contrast, the sentence“planet Apollo is a gas giant by their assigned scientific designation. The reason given like Jupiter” is heavily - yet invisibly - coated with Coper- by the IAU to not name the planets is that it is consid- nicanism. ered impractical as planets are expected to be common. I One reason given by the IAU for not considering naming advance some reasons as to why this logic is flawed, and sug- the extrasolar planets is that it is a task deemed impractical. gest names for the 403 extrasolar planet candidates known One source is quoted as having said “if planets are found to as of Oct 2009. The names follow a scheme of association occur very frequently in the Universe, a system of individual with the constellation that the host star pertains to, and names for planets might well rapidly be found equally im- therefore are mostly drawn from Roman-Greek mythology. practicable as it is for stars, as planet discoveries progress.” Other mythologies may also be used given that a suitable 1. This leads to a second argument. It is indeed impractical association is established. to name all stars. But some stars are named nonetheless. In fact, all other classes of astronomical bodies are named.
    [Show full text]
  • Occurrence and Core-Envelope Structure of 1–4× Earth-Size Planets Around Sun-Like Stars
    Occurrence and core-envelope structure of 1–4× SPECIAL FEATURE Earth-size planets around Sun-like stars Geoffrey W. Marcya,1, Lauren M. Weissa, Erik A. Petiguraa, Howard Isaacsona, Andrew W. Howardb, and Lars A. Buchhavec aDepartment of Astronomy, University of California, Berkeley, CA 94720; bInstitute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822; and cHarvard-Smithsonian Center for Astrophysics, Harvard University, Cambridge, MA 02138 Edited by Adam S. Burrows, Princeton University, Princeton, NJ, and accepted by the Editorial Board April 16, 2014 (received for review January 24, 2014) Small planets, 1–4× the size of Earth, are extremely common planets. The Doppler reflex velocity of an Earth-size planet − around Sun-like stars, and surprisingly so, as they are missing in orbiting at 0.3 AU is only 0.2 m s 1, difficult to detect with an − our solar system. Recent detections have yielded enough informa- observational precision of 1 m s 1. However, such Earth-size tion about this class of exoplanets to begin characterizing their planets show up as a ∼10-sigma dimming of the host star after occurrence rates, orbits, masses, densities, and internal structures. coadding the brightness measurements from each transit. The Kepler mission finds the smallest planets to be most common, The occurrence rate of Earth-size planets is a major goal of as 26% of Sun-like stars have small, 1–2 R⊕ planets with orbital exoplanet science. With three years of Kepler photometry in periods under 100 d, and 11% have 1–2 R⊕ planets that receive 1–4× hand, two groups worked to account for the detection biases in the incident stellar flux that warms our Earth.
    [Show full text]
  • Chapter 16 the Sun and Stars
    Chapter 16 The Sun and Stars Stargazing is an awe-inspiring way to enjoy the night sky, but humans can learn only so much about stars from our position on Earth. The Hubble Space Telescope is a school-bus-size telescope that orbits Earth every 97 minutes at an altitude of 353 miles and a speed of about 17,500 miles per hour. The Hubble Space Telescope (HST) transmits images and data from space to computers on Earth. In fact, HST sends enough data back to Earth each week to fill 3,600 feet of books on a shelf. Scientists store the data on special disks. In January 2006, HST captured images of the Orion Nebula, a huge area where stars are being formed. HST’s detailed images revealed over 3,000 stars that were never seen before. Information from the Hubble will help scientists understand more about how stars form. In this chapter, you will learn all about the star of our solar system, the sun, and about the characteristics of other stars. 1. Why do stars shine? 2. What kinds of stars are there? 3. How are stars formed, and do any other stars have planets? 16.1 The Sun and the Stars What are stars? Where did they come from? How long do they last? During most of the star - an enormous hot ball of gas day, we see only one star, the sun, which is 150 million kilometers away. On a clear held together by gravity which night, about 6,000 stars can be seen without a telescope.
    [Show full text]
  • The Extragalactic Distance Scale
    The Extragalactic Distance Scale Published in "Stellar astrophysics for the local group" : VIII Canary Islands Winter School of Astrophysics. Edited by A. Aparicio, A. Herrero, and F. Sanchez. Cambridge ; New York : Cambridge University Press, 1998 Calibration of the Extragalactic Distance Scale By BARRY F. MADORE1, WENDY L. FREEDMAN2 1NASA/IPAC Extragalactic Database, Infrared Processing & Analysis Center, California Institute of Technology, Jet Propulsion Laboratory, Pasadena, CA 91125, USA 2Observatories, Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena CA 91101, USA The calibration and use of Cepheids as primary distance indicators is reviewed in the context of the extragalactic distance scale. Comparison is made with the independently calibrated Population II distance scale and found to be consistent at the 10% level. The combined use of ground-based facilities and the Hubble Space Telescope now allow for the application of the Cepheid Period-Luminosity relation out to distances in excess of 20 Mpc. Calibration of secondary distance indicators and the direct determination of distances to galaxies in the field as well as in the Virgo and Fornax clusters allows for multiple paths to the determination of the absolute rate of the expansion of the Universe parameterized by the Hubble constant. At this point in the reduction and analysis of Key Project galaxies H0 = 72km/ sec/Mpc ± 2 (random) ± 12 [systematic]. Table of Contents INTRODUCTION TO THE LECTURES CEPHEIDS BRIEF SUMMARY OF THE OBSERVED PROPERTIES OF CEPHEID
    [Show full text]
  • A Basic Requirement for Studying the Heavens Is Determining Where In
    Abasic requirement for studying the heavens is determining where in the sky things are. To specify sky positions, astronomers have developed several coordinate systems. Each uses a coordinate grid projected on to the celestial sphere, in analogy to the geographic coordinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth's equator) . Each coordinate system is named for its choice of fundamental plane. The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the one most closely related to the geographic coordinate system, because they use the same fun­ damental plane and the same poles. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles on to the celest ial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate systems: the geographic system is fixed to the Earth; it rotates as the Earth does . The equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but of course it's really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec for short) . It measures the angle of an object above or below the celestial equator. The longitud inal angle is called the right ascension (RA for short).
    [Show full text]
  • GU Monocerotis: a High-Mass Eclipsing Overcontact Binary in the Young Open Cluster Dolidze 25? J
    A&A 590, A45 (2016) Astronomy DOI: 10.1051/0004-6361/201628224 & c ESO 2016 Astrophysics GU Monocerotis: A high-mass eclipsing overcontact binary in the young open cluster Dolidze 25? J. Lorenzo1, I. Negueruela1, F. Vilardell2, S. Simón-Díaz3; 4, P. Pastor5, and M. Méndez Majuelos6 1 Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Escuela Politécnica Superior, Universidad de Alicante, Carretera de San Vicente del Raspeig s/n, 03690 San Vicente del Raspeig, Alicante, Spain e-mail: [email protected] 2 Institut d’Estudis Espacials de Catalunya, Edifici Nexus, c/ Capitá, 2−4, desp. 201, 08034 Barcelona, Spain 3 Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain 4 Departamento de Astrofísica, Universidad de La Laguna, Facultad de Física y Matemáticas, Avda. Astrofísico Francisco Sánchez s/n, 38205 La Laguna, Tenerife, Spain 5 Departamento de Lenguajes y Sistemas Informáticos, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain 6 Departamento de Ciencias, IES Arroyo Hondo, c/ Maestro Manuel Casal 2, 11520 Rota, Cádiz, Spain Received 30 January 2016 / Accepted 3 March 2016 ABSTRACT Context. The eclipsing binary GU Mon is located in the star-forming cluster Dolidze 25, which has the lowest metallicity measured in a Milky Way young cluster. Aims. GU Mon has been identified as a short-period eclipsing binary with two early B-type components. We set out to derive its orbital and stellar parameters. Methods. We present a comprehensive analysis, including B and V light curves and 11 high-resolution spectra, to verify the orbital period and determine parameters.
    [Show full text]
  • 19 6 6Apj. . .14 6. .743D the VARIABILITY of RHO PUPPIS* I. J
    .743D 6. .14 THE VARIABILITY OF RHO PUPPIS* . I. J. Danziger and L. V. Kumf 6ApJ. Mount Wilson and Palomar Observatories 6 19 Carnegie Institution of Washington, California Institute of Technology Received April 30, 1966 ABSTRACT The results of simultaneous spectrophotometric and spectral observations of the short-period variable star, p Puppis, are reported. The amplitudes of radial-velocity, light, and temperature variations are 11 km/sec, 0.15 mag., and 280° K, respectively. The relative phases differ from those observed in cluster- type c variables. Estimates of the absolute luminosity and mass from the observed gravity and the Py/(p/po) — Q relationship indicate that either p Puppis is pulsating in a higher-order harmonic mode than the first or the theory of its pulsation is not understood. I. INTRODUCTION The bright star p Puppis, classified in the MKK system as type F6II, was first shown to be variable in light (period 0.141 days) by Eggen (1956) who measured a total ampli- tude of 0.15 mag. Struve, Sahade, and Zebergs (1956) showed that there is an associated variation in radial velocity with a total amplitude of 10 km/sec and that maximum brightness occurs approximately 0.02 days later than minimum radial velocity. Bappu (1959) reported that two-color measurements indicate a variation in temperature of 300° K. An intrinsic luminosity of p Puppis, MPg = +2.4, was obtained by Kinman (1959). He assumed it fitted the observed period-luminosity relation of cluster-type c variables in order to use an observed period-luminosity relation. Strömgren’s c-l sys- tem indices were measured by McNamara and Augason (1962) to derive Mpg = +1.7 and a mass 9J£ = 3.2 $)îo from the period-density law with the pulsation constant Q ~ 0-041* It is of interest to note that, although p Puppis has been classified as a ô Scuti star, none of the multiple-period characteristics associated with such stars has been found to apply to it.
    [Show full text]
  • The Kinematic Signature of the Galactic Warp in Gaia DR1-I. the Hipparcos Subsample
    Astronomy & Astrophysics manuscript no. WarpGaia c ESO 2021 September 26, 2021 The kinematic signature of the Galactic warp in Gaia DR1 I. The Hipparcos sub-sample E. Poggio1; 2, R. Drimmel2, R. L. Smart2; 3, A. Spagna2, and M. G. Lattanzi2 1 Università di Torino, Dipartimento di Fisica, via P. Giuria 1, 10125 Torino, Italy 2 Osservatorio Astrofisico di Torino, Istituto Nazionale di Astrofisica (INAF), Strada Osservatorio 20, 10025 Pino Torinese, Italy 3 School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK ABSTRACT Context. The mechanism responsible for the warp of our Galaxy, as well as its dynamical nature, continues to remain unknown. With the advent of high precision astrometry, new horizons have been opened for detecting the kinematics associated with the warp and constraining possible warp formation scenarios for the Milky Way. Aims. The aim of this contribution is to establish whether the first Gaia data release (DR1) shows significant evidence of the kinematic signature expected from a long-lived Galactic warp in the kinematics of distant OB stars. As the first paper in a series, we present our approach for analyzing the proper motions and apply it to the sub-sample of Hipparcos stars. Methods. We select a sample of 989 distant spectroscopically-identified OB stars from the New Reduction of Hipparcos (van Leeuwen 2008), of which 758 are also in the first Gaia data release (DR1), covering distances from 0.5 to 3 kpc from the Sun. We develop a model of the spatial distribution and kinematics of the OB stars from which we produce the probability distribution functions of the proper motions, with and without the systematic motions expected from a long-lived warp.
    [Show full text]