DOCSLIB.ORG

Beta Hydri G2 Iv : a Revised Age for the Closest Subgiant

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

397 BETA HYDRI G2 IV: A REVISED AGE FOR THE CLOSEST SUBGIANT 1 1 2 Dainis Dravins , Lennart Lindegren , Don A. VandenBerg 1 Lund Observatory,Box 43, SE-22100 Lund, Sweden 2 DepartmentofPhysics and Astronomy, Univ. of Victoria, P.O. Box 3055, Victoria, B.C., Canada V8W 3P6 2. BETA HYDRI | THE STAR ABSTRACT The characteristics of Hyi are typical of the old The secular evolution of solar-typ e atmospheres may Galactic disk p opulation: e.g. a feeble chromospheric be studied through comparisons of the current Sun activity and an eccentric Galactic orbit. As exp ected with old solar-typ e stars of known age. Among the for an old star, Hyi is slightly metal p o or, with few such stars in the solar Galactic neighborhood, log Fe/H determinations relative to the Sun around Hydri G2 IV stands out as a normal single star 0:2. While the abundances of heavier metals are with an advanced age. Previous age determinations low, lithium is abundant a signature shared with ' 9:5 Gy were based on the old ground-based other older subgiants, p ermitting analyses of stellar parallax of 153 mas. The new Hipparcos value of internal evolution in the p ost-main-sequence stages. 133:78 0:51 mas implies an absolute magnitude Various determinations set the e ective temp erature M = 3:43 0:01, 0.3 mag brighter than previ- V to 5800 100 K, equal to the commonly accepted ously b elieved. New evolutionary calculations pro- value for the Sun of T = 5780 30 K. For a re- e duce b est- t mo dels with ages around 6.7 Gy. Al- view of the basic stellar parameters, see Dravins et though the Hipparcos data thus lead to a signi cant al. 1993a. reduction of its age, Hyi remains an old star. Key words: space astrometry; stars: evolution; stars: 3. HIPPARCOS OBSERVATIONS individual; stars: late-typ e. Hipparcos data ESA 1997 for Hyi give the par- allax 133:78 0:51 mas. The prop er-motion mea- surements indicate a steady stellar motion, with no indications of duplicity or other irregularities. The 1. INTRODUCTION photometry gives Hp =2:9305 0:0003 mag, which for V I =0:68 mag corresp onds to V =2:801 mag, as transformed to the Johnson system. This is fully How do solar-typ e atmospheres evolve along with the consistent with the Hipparcos input catalogue value stellar evolution? Will the Sun still have a magnetic of V =2:82 mag. No photometric variability could activity cycle billions of years in the future, after it b e detected by Hipparcos, with an upp er amplitude has left the main sequence? Answers to questions limit of ' 0:004 mag. such as these may be found by studying old solar- typ e stars, taken to represent the future Sun. Such stars must have reliable age determinations, and b e 4. BETA HYDRI | THE AGE bright enough for detailed sp ectroscopy. Among old and single stars, accurate age determinations are p os- sible for G subgiants that haveevolved slightly o the 4.1. The Previous Old Age main sequence, yet are still suciently close to it to avoid ambiguities in stellar evolutionary tracks. The age of Hyi was previously determined bymod- eling evolutionary tracks across its lo cation in the The closest and brightest m = 2:8 among such V Hertzsprung-Russell diagram, as inferred from its stars in the solar Galactic neighb orho o d is Hydri parallax measured early in this century. The General HR 98; HD 2151; HIP 2021, of sp ectral typ e G2 IV. Catalogue of Trigonometric Stel lar Paral laxes listed Detailed studies of its photospheric structure, chro- the absolute parallax as 153 10 mas standard error, mospheric and transition zone emission, and of coro- probable error 7 mas; Jenkins 1952. After incorp o- nal X-ray uxes have b een made, making Hyi one of rating some additional observations, this value was the b est-studied individual stars other than the Sun slightly mo di ed to 150:1 7:2 mas in the latest edi- Dravins et al. 1993a,b,c; Dorren et al. 1995; Gudel tion van Altena et al. 1995. et al. 1997. 398 3 β Hyi 1.05 M 7 1.11 M 5 4 V 3 M 1 Gy Sun 5 3.80 3.75 3.70 log Teff [K] Figure 1. Stel lar evolution, and the age of Beta Hydri. Post-main-sequence tracks are shown for two representative models, passing through the post-Hipparcos position of Hyi in the M /log T plane black diamond. The position V e based on the old ground-basedparal lax is also marked grey diamond. Atbottom, a track for a solar model evolved until 4.6 Gy demonstrates that the present solar luminosity and temperatureareaccurately reproduced for the adoptedmodel parameters. of elements, and the same nuclear reaction rates as The most detailed previous age determination gave in standard solar mo dels Bahcall & Pinsonneault values around 9.5 Gy Dravins et al. 1993a. Also ear- 1992; Guenther et al. 1992a, b. It incorp orates low- lier work had arrived at ages in the 8{10 Gy range: temp erature opacities similar to those rep orted by Cayrel de Strob el 1981; Hearnshaw 1972, 1973; Per- Alexander & Ferguson 1994, and an equation of rin et al. 1977. Such an age ts well with that esti- state with Coulomb corrections and other non-ideal mated for the Galactic disk. The main observational e ects; see VandenBerg et al. 1997 for a detailed uncertaintywas due to the parallax error, while er- discussion of the adopted physics. These improve- rors in T play almost no role since Hyi is rapidly e ments lead to a solar helium abundance Y ' 0:27 evolving nearly horizontally in the HR diagram. rather than ' 0:28, when the Coulomb interaction is ignored. As b efore, the e ective temp erature was adopted as 5800 K. 4.2. The New Old Age A number of evolutionary tracks were computed, a few of which are shown in Figure 1. As a mo del veri - The availability of the new, and very much more ac- cation, a track for a standard solar mo del shows that curate, parallax from Hipparcos now p ermits a more the present luminosity M = 4:72; M = 4:84 precise determination of the evolutionary status for bol V and temp erature of the Sun are accurately repro- Hyi. The signi cance of such a new determination duced for the adopted choices of Y and mixing-length lies also in that the Hipparcos value rather signif- parameter. icantly by two standard errors deviates from the previous ground-based estimate. The Hipparcos par- Mo dels were computed for the slightly di erent allax yields the absolute magnitude M =3:430:01, V metallicities Z = 0:0100, 0.0125, and 0.0150, with some 0.3 mag brighter than previously b elieved. the same Y as needed to t the Sun. Another mo del for Z = 0:0125 had a helium abundance lower by New evolutionary calculations have b een made, us- Y =0:01. The four mo dels assume masses that are ing a considerably improved version of the program necessary, for the various choices of Z and Y ,tointer- co de used in previous calculations VandenBerg 1992; sect the p osition of Hyi in the M = log T plane. Dravins et al. 1993a; and references in these pap ers. V e The choices of Z should encompass the true metallic- This new version uses recentOPAL opacities Rogers ity corresp onding to the logarithmic values relative & Iglesias 1992 for the No els & Grevesse 1993 mix 399 REFERENCES Table 1. Interpolating in the tracks at the M ;T value V e of Hyi, one nds the ages [Gy]. Alexander, D.R., Ferguson, J.W. 1994, ApJ 437, 879 Bahcall, J.N., Pinsonneault, M.H. 1992, Rev. Mo d. Z Y [Me/H] Mass Age Phys. 64, 885 0.0100 0.2716 0:28 1.053 6.83 Cayrel de Strob el, G. 1981, Bull. Inform. CDS 20, 28 0.0125 0.2716 0:20 1.095 6.52 Dorren, J.D., Gudel, M., Guinan, E.F. 1995 ApJ 448, 0.0150 0.2716 0:10 1.228 6.31 431 0.0125 0.2616 0:20 1.109 6.64 Dravins, D., Lindegren, L., Nordlund, A., Vanden- Berg, D.A. 1993a, ApJ 403, 385 Dravins, D., Linde, P., Fredga, K., Gahm, G.F. 1993b, ApJ 403, 396 to hydrogen [Me=H] '0:28, 0:20, and 0:10, re- Dravins, D., Linde, P., Ayres, T.R., Linsky, J.L., sp ectively. Interp olating in the tracks for the age Monsignori-Fossi, B.,Simon, T., Wallinder, F. at the M ;T value of Hyi, one nds Figure 1 1993c, ApJ, 403, 412 V e and Table 1 that b est- t mo dels have parameters ESA, 1997, The Hipparcos and Tycho Catalogues, around: mass = 1:1 M ; Y =0:27, Z =0:011 cor- ESA SP{1200 resp onding to a metallicity log [Me=H] around 0:2; Gudel, M., Guinan, E.F., Skinner, S.L. 1997, ApJ, in T = 5800 K, and ages around 6.7 Gy. e press In Figure 1, the sup erp osed symb ols mark every bil- Guenther, D.B., Demarque, P., Kim, Y.C., Pinson- lion of years, starting from the pre-main-sequence neault, M.H. 1992a, ApJ 387, 372 zero age. The long-dashed curve is for a mo del with Guenther, D.B., Demarque, P., Pinsonneault, M.H., mass = 1:053 M , the dotted one for 1:109 M , Kim, Y.C.
Recommended publications
  • The Dunhuang Chinese Sky: a Comprehensive Study of the Oldest Known Star Atlas

    The Dunhuang Chinese Sky: a Comprehensive Study of the Oldest Known Star Atlas

    25/02/09JAHH/v4 1 THE DUNHUANG CHINESE SKY: A COMPREHENSIVE STUDY OF THE OLDEST KNOWN STAR ATLAS JEAN-MARC BONNET-BIDAUD Commissariat à l’Energie Atomique ,Centre de Saclay, F-91191 Gif-sur-Yvette, France E-mail: [email protected] FRANÇOISE PRADERIE Observatoire de Paris, 61 Avenue de l’Observatoire, F- 75014 Paris, France E-mail: [email protected] and SUSAN WHITFIELD The British Library, 96 Euston Road, London NW1 2DB, UK E-mail: [email protected] Abstract: This paper presents an analysis of the star atlas included in the medieval Chinese manuscript (Or.8210/S.3326), discovered in 1907 by the archaeologist Aurel Stein at the Silk Road town of Dunhuang and now held in the British Library. Although partially studied by a few Chinese scholars, it has never been fully displayed and discussed in the Western world. This set of sky maps (12 hour angle maps in quasi-cylindrical projection and a circumpolar map in azimuthal projection), displaying the full sky visible from the Northern hemisphere, is up to now the oldest complete preserved star atlas from any civilisation. It is also the first known pictorial representation of the quasi-totality of the Chinese constellations. This paper describes the history of the physical object – a roll of thin paper drawn with ink. We analyse the stellar content of each map (1339 stars, 257 asterisms) and the texts associated with the maps. We establish the precision with which the maps are drawn (1.5 to 4° for the brightest stars) and examine the type of projections used.
  • Constraining the Masses of Microlensing Black Holes and the Mass Gap with Gaia DR2 Łukasz Wyrzykowski1 and Ilya Mandel2,3,4

    Constraining the Masses of Microlensing Black Holes and the Mass Gap with Gaia DR2 Łukasz Wyrzykowski1 and Ilya Mandel2,3,4

    A&A 636, A20 (2020) Astronomy https://doi.org/10.1051/0004-6361/201935842 & c ESO 2020 Astrophysics Constraining the masses of microlensing black holes and the mass gap with Gaia DR2 Łukasz Wyrzykowski1 and Ilya Mandel2,3,4 1 Warsaw University Astronomical Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland e-mail: [email protected] 2 Monash Centre for Astrophysics, School of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia 3 OzGrav: The ARC Center of Excellence for Gravitational Wave Discovery, Australia 4 Institute of Gravitational Wave Astronomy and School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK Received 6 May 2019 / Accepted 27 January 2020 ABSTRACT Context. Gravitational microlensing is sensitive to compact-object lenses in the Milky Way, including white dwarfs, neutron stars, or black holes, and could potentially probe a wide range of stellar-remnant masses. However, the mass of the lens can be determined only in very limited cases, due to missing information on both source and lens distances and their proper motions. Aims. Our aim is to improve the mass estimates in the annual parallax microlensing events found in the eight years of OGLE-III observations towards the Galactic Bulge with the use of Gaia Data Release 2 (DR2). Methods. We use Gaia DR2 data on distances and proper motions of non-blended sources and recompute the masses of lenses in parallax events. We also identify new events in that sample which are likely to have dark lenses; the total number of such events is now 18. Results.
  • Arxiv:1703.10181V1 [Astro-Ph.SR] 29 Mar 2017 Ordo H G.W Alteesas“E Stragglers” “Red Stars These Call We Similar Found RGB

    Arxiv:1703.10181V1 [Astro-Ph.SR] 29 Mar 2017 Ordo H G.W Alteesas“E Stragglers” “Red Stars These Call We Similar Found RGB

    Draft version October 15, 2018 Preprint typeset using LATEX style emulateapj v. 01/23/15 ON THE ORIGIN OF SUB-SUBGIANT STARS II: BINARY MASS TRANSFER, ENVELOPE STRIPPING, AND MAGNETIC ACTIVITY Emily Leiner1, Robert D. Mathieu1, and Aaron M. Geller2,3 Draft version October 15, 2018 ABSTRACT Sub-subgiant stars (SSGs) lie to the red of the main-sequence and fainter than the red giant branch in cluster color-magnitude diagrams (CMDs), a region not easily populated by standard stellar evo- lution pathways. While there has been speculation on what mechanisms may create these unusual stars, no well-developed theory exists to explain their origins. Here we discuss three hypotheses of SSG formation: (1) mass transfer in a binary system, (2) stripping of a subgiant’s envelope, perhaps during a dynamical encounter, and (3) reduced luminosity due to magnetic fields that lower convective efficiency and produce large star spots. Using the stellar evolution code MESA, we develop evolu- tionary tracks for each of these hypotheses, and compare the expected stellar and orbital properties of these models with six known SSGs in the two open clusters M67 and NGC 6791. All three of these mechanisms can create stars or binary systems in the SSG CMD domain. We also calculate the frequency with which each of these mechanisms may create SSG systems, and find that the magnetic field hypothesis is expected to create SSGs with the highest frequency in open clusters. Mass transfer and envelope stripping have lower expected formation frequencies, but may nevertheless create occa- sional SSGs in open clusters. They may also be important mechanisms to create SSGs in higher mass globular clusters.
  • Spectroscopy of Variable Stars

    Spectroscopy of Variable Stars

    Spectroscopy of Variable Stars Steve B. Howell and Travis A. Rector The National Optical Astronomy Observatory 950 N. Cherry Ave. Tucson, AZ 85719 USA Introduction A Note from the Authors The goal of this project is to determine the physical characteristics of variable stars (e.g., temperature, radius and luminosity) by analyzing spectra and photometric observations that span several years. The project was originally developed as a The 2.1-meter telescope and research project for teachers participating in the NOAO TLRBSE program. Coudé Feed spectrograph at Kitt Peak National Observatory in Ari- Please note that it is assumed that the instructor and students are familiar with the zona. The 2.1-meter telescope is concepts of photometry and spectroscopy as it is used in astronomy, as well as inside the white dome. The Coudé stellar classification and stellar evolution. This document is an incomplete source Feed spectrograph is in the right of information on these topics, so further study is encouraged. In particular, the half of the building. It also uses “Stellar Spectroscopy” document will be useful for learning how to analyze the the white tower on the right. spectrum of a star. Prerequisites To be able to do this research project, students should have a basic understanding of the following concepts: • Spectroscopy and photometry in astronomy • Stellar evolution • Stellar classification • Inverse-square law and Stefan’s law The control room for the Coudé Description of the Data Feed spectrograph. The spec- trograph is operated by the two The spectra used in this project were obtained with the Coudé Feed telescopes computers on the left.
  • 1999-2000 Annual Report

    1999-2000 Annual Report

    Anglo-Australian Observatory Annual Report of the Anglo-Australian Telescope Board 1 July 1999 to 30 June 2000 ANGLO-AUSTRALIAN OBSERVATORY PO Box 296, Epping, NSW 1710, Australia 167 Vimiera Road, Eastwood, NSW 2122, Australia PH (02) 9372 4800 (international) + 61 2 9372 4800 FAX (02) 9372 4880 (international) + 61 2 9372 4880 e-mail [email protected] ANGLO-AUSTRALIAN TELESCOPE BOARD PO Box 296, Epping, NSW 1710, Australia 167 Vimiera Road, Eastwood, NSW 2122, Australia PH (02) 9372 4813 (international) + 61 2 9372 4813 FAX (02) 9372 4880 (international) + 61 2 9372 4880 e-mail [email protected] ANGLO-AUSTRALIAN TELESCOPE/UK SCHMIDT TELESCOPE PriVate Bag, Coonabarabran, NSW 2357, Australia PH (02) 6842 6291 (international) + 61 2 6842 6291 AAT FAX (02) 6884 2298 (international) + 61 2 6884 298 UKST FAX (02) 6842 2288 (international) + 61 2 6842 2288 WWW http://www.aao.gov.au/ © Anglo-Australian Telescope Board 2000 ISSN 1443-8550 COVER: A digital image of the Antennae galaxies (NGC4038-39) made by combining three images from the Tek2 CCD on the AAT (Steve Lee and David Malin). A new wide field CCD Imager (WFI) will come into use in 2000 and will enable many more images like this to be made. COVER DESIGN: Encore International COMPUTER TYPESET AT THE: Anglo-Australian ObserVatory ii The Right Honourable Stephen Byers, MP, President of the Board of Trade and Secretary of State for Trade and Industry, Government of the United Kingdom of Great Britain and Northern Ireland The Honourable Dr David Kemp, MP, Minister for Education, Training and Youth Affairs GoVernment of the Commonwealth of Australia In accordance with Article 8 of the Agreement between the Australian GoVernment and the GoVernment of the United Kingdom to proVide for the establishment and operation of an optical telescope at Siding Spring Mountain in the state of New South Wales, I present herewith a report by the Anglo-Australian Telescope Board for the year from 1 July 1999 to 30 June 2000.
  • The Chemical Composition of Solar-Type Stars and Its Impact on the Presence of Planets

    The Chemical Composition of Solar-Type Stars and Its Impact on the Presence of Planets

    The chemical composition of solar-type stars and its impact on the presence of planets Patrick Baumann Munchen¨ 2013 The chemical composition of solar-type stars and its impact on the presence of planets Patrick Baumann Dissertation der Fakultat¨ fur¨ Physik der Ludwig-Maximilians-Universitat¨ Munchen¨ durchgefuhrt¨ am Max-Planck-Institut fur¨ Astrophysik vorgelegt von Patrick Baumann aus Munchen¨ Munchen,¨ den 31. Januar 2013 Erstgutacher: Prof. Dr. Achim Weiss Zweitgutachter: Prof. Dr. Joachim Puls Tag der mündlichen Prüfung: 8. April 2013 Zusammenfassung Wir untersuchen eine mogliche¨ Verbindung zwischen den relativen Elementhaufig-¨ keiten in Sternatmospharen¨ und der Anwesenheit von Planeten um den jeweili- gen Stern. Um zuverlassige¨ Ergebnisse zu erhalten, untersuchen wir ausschließlich sonnenahnliche¨ Sterne und fuhren¨ unsere spektroskopischen Analysen zur Bestim- mung der grundlegenden Parameter und der chemischen Zusammensetzung streng differenziell und relativ zu den solaren Werten durch. Insgesamt untersuchen wir 200 Sterne unter Zuhilfenahme von Spektren mit herausragender Qualitat,¨ die an den modernsten Teleskopen gewonnen wurden, die uns zur Verfugung¨ stehen. Mithilfe der Daten fur¨ 117 sonnenahnliche¨ Sterne untersuchen wir eine mogliche¨ Verbindung zwischen der Oberflachenh¨ aufigkeit¨ von Lithium in einem Stern, seinem Alter und der Wahrscheinlichkeit, dass sich ein oder mehrere Sterne in einer Um- laufbahn um das Objekt befinden. Fur¨ jeden Stern erhalten wir sehr exakte grundle- gende Parameter unter Benutzung einer sorgfaltig¨ zusammengestellten Liste von Fe i- und Fe ii-absorptionslinien, modernen Modellatmospharen¨ und Routinen zum Erstellen von Modellspektren. Die Massen und das Alter der Objekte werden mithilfe von Isochronen bestimmt, was zu sehr soliden relativen Werten fuhrt.¨ Bei jungen Sternen, fur¨ die die Isochronenmethode recht unzuverlssig¨ ist, vergleichen wir verschiedene alternative Methoden.
  • STELLAR RADIO ASTRONOMY: Probing Stellar Atmospheres from Protostars to Giants

    STELLAR RADIO ASTRONOMY: Probing Stellar Atmospheres from Protostars to Giants

    30 Jul 2002 9:10 AR AR166-AA40-07.tex AR166-AA40-07.SGM LaTeX2e(2002/01/18) P1: IKH 10.1146/annurev.astro.40.060401.093806 Annu. Rev. Astron. Astrophys. 2002. 40:217–61 doi: 10.1146/annurev.astro.40.060401.093806 Copyright c 2002 by Annual Reviews. All rights reserved STELLAR RADIO ASTRONOMY: Probing Stellar Atmospheres from Protostars to Giants Manuel Gudel¨ Paul Scherrer Institut, Wurenlingen¨ & Villigen, CH-5232 Villigen PSI, Switzerland; email: [email protected] Key Words radio stars, coronae, stellar winds, high-energy particles, nonthermal radiation, magnetic fields ■ Abstract Radio astronomy has provided evidence for the presence of ionized atmospheres around almost all classes of nondegenerate stars. Magnetically confined coronae dominate in the cool half of the Hertzsprung-Russell diagram. Their radio emission is predominantly of nonthermal origin and has been identified as gyrosyn- chrotron radiation from mildly relativistic electrons, apart from some coherent emission mechanisms. Ionized winds are found in hot stars and in red giants. They are detected through their thermal, optically thick radiation, but synchrotron emission has been found in many systems as well. The latter is emitted presumably by shock-accelerated electrons in weak magnetic fields in the outer wind regions. Radio emission is also frequently detected in pre–main sequence stars and protostars and has recently been discovered in brown dwarfs. This review summarizes the radio view of the atmospheres of nondegenerate stars, focusing on energy release physics in cool coronal stars, wind phenomenology in hot stars and cool giants, and emission observed from young and forming stars. Eines habe ich in einem langen Leben gelernt, namlich,¨ dass unsere ganze Wissenschaft, an den Dingen gemessen, von kindlicher Primitivitat¨ ist—und doch ist es das Kostlichste,¨ was wir haben.
  • Arxiv:1903.09211V1 [Astro-Ph.HE] 21 Mar 2019

    Arxiv:1903.09211V1 [Astro-Ph.HE] 21 Mar 2019

    Accepted to ApJ - March 20, 2019 Preprint typeset using LATEX style emulateapj v. 01/23/15 PSR J1306{40: AN X-RAY LUMINOUS REDBACK WITH AN EVOLVED COMPANION Samuel J. Swihart1, Jay Strader1, Laura Chomiuk1, Laura Shishkovsky1 1Center for Data Intensive and Time Domain Astronomy, Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA Accepted to ApJ - March 20, 2019 ABSTRACT PSR J1306{40 is a millisecond pulsar binary with a non-degenerate companion in an unusually long ∼1.097 day orbit. We present new optical photometry and spectroscopy of this system, and model these data to constrain fundamental properties of the binary such as the component masses and distance. The optical data imply a minimum neutron star mass of 1:75 ± 0:09 M (1-sigma) and a high, nearly edge-on inclination. The light curves suggest a large hot spot on the companion, suggestive of a portion of the pulsar wind being channeled to the stellar surface by the magnetic field of the secondary, mediated via an intrabinary shock. The Hα line profiles switch rapidly from emission to absorption near companion inferior conjunction, consistent with an eclipse of the compact emission region at these phases. At our optically-inferred distance of 4:7 ± 0:5 kpc, the X-ray luminosity is ∼1033 erg s-1, brighter than nearly all known redbacks in the pulsar state. The long period, subgiant-like secondary, and luminous X-ray emission suggest this system may be part of the expanding class of millisecond pulsar binaries that are progenitors to typical field pulsar{white dwarf binaries.
  • Arxiv:1803.04461V1 [Astro-Ph.SR] 12 Mar 2018 (Received; Revised March 14, 2018) Submitted to Apj

    Arxiv:1803.04461V1 [Astro-Ph.SR] 12 Mar 2018 (Received; Revised March 14, 2018) Submitted to Apj

    Draft version March 14, 2018 Typeset using LATEX preprint style in AASTeX61 CHEMICAL ABUNDANCES OF MAIN-SEQUENCE, TURN-OFF, SUBGIANT AND RED GIANT STARS FROM APOGEE SPECTRA I: SIGNATURES OF DIFFUSION IN THE OPEN CLUSTER M67 Diogo Souto,1 Katia Cunha,2, 1 Verne V. Smith,3 C. Allende Prieto,4, 5 D. A. Garc´ıa-Hernandez,´ 4, 5 Marc Pinsonneault,6 Parker Holzer,7 Peter Frinchaboy,8 Jon Holtzman,9 J. A. Johnson,6 Henrik Jonsson¨ ,10 Steven R. Majewski,11 Matthew Shetrone,12 Jennifer Sobeck,11 Guy Stringfellow,13 Johanna Teske,14 Olga Zamora,4, 5 Gail Zasowski,7 Ricardo Carrera,15 Keivan Stassun,16 J. G. Fernandez-Trincado,17, 18 Sandro Villanova,17 Dante Minniti,19 and Felipe Santana20 1Observat´orioNacional, Rua General Jos´eCristino, 77, 20921-400 S~aoCrist´ov~ao,Rio de Janeiro, RJ, Brazil 2Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065, USA 3National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA 4Instituto de Astrof´ısica de Canarias, E-38205 La Laguna, Tenerife, Spain 5Departamento de Astrof´ısica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain 6Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA 7Department of Physics and Astronomy, The University of Utah, Salt Lake City, UT 84112, USA 8Department of Physics & Astronomy, Texas Christian University, Fort Worth, TX, 76129, USA 9New Mexico State University, Las Cruces, NM 88003, USA 10Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43,
  • New Wide Common Proper Motion Binaries

    New Wide Common Proper Motion Binaries

    Vol. 6 No. 1 January 1, 2010 Journal of Double Star Observations Page 30 New Wide Common Proper Motion Binaries Rafael Benavides1,2, Francisco Rica2,3, Esteban Reina4, Julio Castellanos5, Ramón Naves6, Luis Lahuerta7, Salvador Lahuerta7 1. Astronomical Society of Córdoba, Observatory of Posadas, MPC-IAU Code J53, C/.Gaitán nº 20, 1º, 14730 Posadas (Spain) 2. Double Star Section of Liga Iberoamericana de Astronomía (LIADA), Avda. Almirante Guillermo Brown No. 4998, 3000 Santa Fe (Argentina) 3. Astronomical Society of Mérida, C/José Ruíz Azorín, 14, 4º D, 06800 Mérida (Spain) 4. Plza. Mare de Dèu de Montserrat, 1 Etlo 2ªB, 08901 L'Hospitalet de Llobregat (Spain) 5. 0bservatory with MPC-IAU Code 939, Av. Primado Reig 183, 46020 Valencia (Spain) 6. Observatory of Montcabrer, MPC-IAU Code 213, C/Jaume Balmes, 24, 08348 Cabrils (Spain) 7. G.E.O.D.A., Observatorio Manises, MPC-IAU Code J98, C/ Mayor, 111-4, 46940 Manises (Spain) Abstract: In this work we report the discovery of 150 new double stars of which 142 are wide common proper motion stellar systems. In addition to this, we report the study of 23 recently catalogued wide common proper motion binaries discovered by other observers. Spectral types, photometric distances, kinematics and ages were determined from data ob- tained consulting the literature. Several criteria were used to determine the nature of each double star. Orbital periods and the semimajor axes were calculated. they are good sensors to detect unknown mass concen- 1. Introduction trations that they may encounter along their galactic For several years double-star amateurs have con- trajectories.
  • Lecture 8: Stellar Motions Reading: Box 19-1

    Lecture 8: Stellar Motions Reading: Box 19-1

    Lecture 8: Stellar Motions Reading: Box 19-1 Key Ideas The stars are in constant motion. Observed Motions Proper motions (motion against the background, measured in angular motion/time) Radial velocities (motion towards or away, measured from the Doppler shift) True Space Motion Combination of radial velocity, proper motion, and distance (important for proper motion!) The “Fixed” Stars Although the stars are moving, their motions across the sky are so small that to the naked eye, the stars appear “fixed” to the sky. Great distances make the amount of motion small on human lifetimes. (Of course, stars moving directly away or towards us will not to appear to move across the sky) Proper Motions Apparent angular motion across the sky of nearby stars with respect to distant objects. (Distant stars are used because we assume that even though they are moving through space they are so far away that from our perspective they are fixed). It is the projection of the star’s true motion through space relative to the Sun. Typical proper motion for stars in the solar neighborhood is about 0.1 arcsec/year Largest proper motion measured is 10.25 arcsec/year Barnard’s Star) Proper motions are cumulative. Effects build up over time. The longer you wait, the greater apparent angular motion is. Measuring proper motions: Compare photos of the sky taken 20 to 50 years apart Measure how much stars have moved compared to more distant background objects (galaxies, quasars). Example: if a star has a proper motion of 0.1 arcsec/year: In one year, it moves 0.1 arcsec In 10 years, it moves 10x0.1= 1 arcsec In 100 years, it moves 100x0.1 =10 arcsec It can take a long time for the constellations to noticeably change shape.
  • Arxiv:1703.10167V1

    Arxiv:1703.10167V1

    Draft version April 9, 2018 Preprint typeset using LATEX style emulateapj v. 08/22/09 ON THE ORIGIN OF SUB-SUBGIANT STARS. I. DEMOGRAPHICS Aaron M. Geller1,2,†,∗, Emily M. Leiner3, Andrea Bellini4, Robert Gleisinger5,6, Daryl Haggard5, Sebastian Kamann7, Nathan W. C. Leigh8, Robert D. Mathieu3, Alison Sills9, Laura L. Watkins4, David Zurek8,10 1Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics & Astronomy, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60201, USA; 2Adler Planetarium, Dept. of Astronomy, 1300 S. Lake Shore Drive, Chicago, IL 60605, USA; 3Department of Astronomy, University of Wisconsin-Madison, WI 53706, USA; 4Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA; 5Department of Physics, McGill University, McGill Space Institute, 3550 University Street, Montreal, QC H3A 2A7, Canada; 6Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada; 7Institut f¨ur Astrophysik, Universit¨at G¨ottingen, Friedrich-Hund-Platz 1, 37077 G¨ottingen, Germany; 8Department of Astrophysics, American Museum of Natural History, Central Park West and 79th Street, New York, NY 10024; 9Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada; 10Visiting Researcher, NRC – Herzberg Astronomy and Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, British Columbia V9E 2E7, Canada Draft version April 9, 2018 ABSTRACT Sub-subgiants are stars observed to be redder than normal main-sequence stars and fainter than normal subgiant (and giant) stars in an optical color-magnitude diagram. The red straggler stars, which lie redward of the red giant branch, may be related and are often grouped together with the sub-subgiants in the literature.