October 2018 BRAS Newsletter
Total Page：16
File Type：pdf, Size：1020Kb
Load more
Recommended publications
-
Nitrogen Abundances in Planet-Harbouring Stars
A&A 418, 703–715 (2004) Astronomy DOI: 10.1051/0004-6361:20035717 & c ESO 2004 Astrophysics Nitrogen abundances in planet-harbouring stars A. Ecuvillon1, G. Israelian1,N.C.Santos2,3, M. Mayor3,R.J.Garc´ıa L´opez1,4, and S. Randich5 1 Instituto de Astrof´ısica de Canarias, 38200 La Laguna, Tenerife, Spain 2 Centro de Astronomia e Astrofisica de Universidade de Lisboa, Observatorio Astronomico de Lisboa, Tapada de Ajuda, 1349-018 Lisboa, Portugal 3 Observatoire de Gen`eve, 51 ch. des Maillettes, 1290 Sauverny, Switzerland 4 Departamento de Astrof´ısica, Universidad de La Laguna, Av. Astrof´ısico Francisco S´anchez s/n, 38206 La Laguna, Tenerife, Spain 5 INAF/Osservatorio Astrofisico di Arcetri, Largo Fermi 5, 50125 Firenze, Italy Received 20 November 2003 / Accepted 4 February 2004 Abstract. We present a detailed spectroscopic analysis of nitrogen abundances in 91 solar-type stars, 66 with and 25 without known planetary mass companions. All comparison sample stars and 28 planet hosts were analysed by spectral synthesis of the near-UV NH band at 3360 Å observed at high resolution with the VLT/UVES, while the near-IR N 7468 Å was measured in 31 objects. These two abundance indicators are in good agreement. We found that nitrogen abundance scales with that of iron in the metallicity range −0.6 < [Fe/H] < +0.4 with the slope 1.08 ± 0.05. Our results show that the bulk of nitrogen production at high metallicities was coupled with iron. We found that the nitrogen abundance distribution in stars with exoplanets is the high [Fe/H] extension of the curve traced by the comparison sample of stars with no known planets. -
Appendix 1 Some Astrophysical Reminders
Appendix 1 Some Astrophysical Reminders Marc Ollivier 1.1 A Physics and Astrophysics Overview 1.1.1 Star or Planet? Roughly speaking, we can say that the physics of stars and planets is mainly governed by their mass and thus by two effects: 1. Gravitation that tends to compress the object, thus releasing gravitational energy 2. Nuclear processes that start as the core temperature of the object increases The mass is thus a good parameter for classifying the different astrophysical objects, the adapted mass unit being the solar mass (written Ma). As the mass decreases, three categories of objects can be distinguished: ∼ 1. if M>0.08 Ma ( 80MJ where MJ is the Jupiter mass) the mass is sufficient and, as a consequence, the gravitational contraction in the core of the object is strong enough to start hydrogen fusion reactions. The object is then called a “star” and its radius is proportional to its mass. 2. If 0.013 Ma <M<0.08 Ma (13 MJ <M<80 MJ), the core temperature is not high enough for hydrogen fusion reactions, but does allow deuterium fu- sion reactions. The object is called a “brown dwarf” and its radius is inversely proportional to the cube root of its mass. 3. If M<0.013 Ma (M<13 MJ) the temperature a the center of the object does not permit any nuclear fusion reactions. The object is called a “planet”. In this category one distinguishes giant gaseous and telluric planets. This latter is not massive enough to accrete gas. The mass limit between giant and telluric planets is about 10 terrestrial masses. -
![Arxiv:0804.4630V1 [Astro-Ph] 29 Apr 2008 I Ehnv20;Ficao 06) Ti Nti Oeas Role This in Is It 2006A)](https://docslib.b-cdn.net/cover/8871/arxiv-0804-4630v1-astro-ph-29-apr-2008-i-ehnv20-ficao-06-ti-nti-oeas-role-this-in-is-it-2006a-158871.webp)
Arxiv:0804.4630V1 [Astro-Ph] 29 Apr 2008 I Ehnv20;Ficao 06) Ti Nti Oeas Role This in Is It 2006A)
DRAFT VERSION NOVEMBER 9, 2018 Preprint typeset using LATEX style emulateapj v. 05/04/06 OPEN CLUSTERS AS GALACTIC DISK TRACERS: I. PROJECT MOTIVATION, CLUSTER MEMBERSHIP AND BULK THREE-DIMENSIONAL KINEMATICS PETER M. FRINCHABOY1,2,3 AND STEVEN R. MAJEWSKI2 Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA Draft version November 9, 2018 ABSTRACT We have begun a survey of the chemical and dynamical properties of the Milky Way disk as traced by open star clusters. In this first contribution, the general goals of our survey are outlined and the strengths and limita- tions of using star clusters as a Galactic disk tracer sample are discussed. We also present medium resolution (R 15,0000) spectroscopy of open cluster stars obtained with the Hydra multi-object spectrographs on the Cerro∼ Tololo Inter-American Observatory 4-m and WIYN 3.5-m telescopes. Here we use these data to deter- mine the radial velocities of 3436 stars in the fields of open clusters within about 3 kpc, with specific attention to stars having proper motions in the Tycho-2 catalog. Additional radial velocity members (without Tycho-2 proper motions) that can be used for future studies of these clusters were also identified. The radial velocities, proper motions, and the angular distance of the stars from cluster center are used to derive cluster member- ship probabilities for stars in each cluster field using a non-parametric approach, and the cluster members so-identified are used, in turn, to derive the reliable bulk three-dimensional motion for 66 of 71 targeted open clusters. -
Li Abundances in F Stars: Planets, Rotation, and Galactic Evolution ,
A&A 576, A69 (2015) Astronomy DOI: 10.1051/0004-6361/201425433 & c ESO 2015 Astrophysics Li abundances in F stars: planets, rotation, and Galactic evolution, E. Delgado Mena1,2, S. Bertrán de Lis3,4, V. Zh. Adibekyan1,2,S.G.Sousa1,2,P.Figueira1,2, A. Mortier6, J. I. González Hernández3,4,M.Tsantaki1,2,3, G. Israelian3,4, and N. C. Santos1,2,5 1 Centro de Astrofisica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal e-mail: [email protected] 2 Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal 3 Instituto de Astrofísica de Canarias, C/via Lactea, s/n, 38200 La Laguna, Tenerife, Spain 4 Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain 5 Departamento de Física e Astronomía, Faculdade de Ciências, Universidade do Porto, Portugal 6 SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, UK Received 28 November 2014 / Accepted 14 December 2014 ABSTRACT Aims. We aim, on the one hand, to study the possible differences of Li abundances between planet hosts and stars without detected planets at effective temperatures hotter than the Sun, and on the other hand, to explore the Li dip and the evolution of Li at high metallicities. Methods. We present lithium abundances for 353 main sequence stars with and without planets in the Teff range 5900–7200 K. We observed 265 stars of our sample with HARPS spectrograph during different planets search programs. We observed the remaining targets with a variety of high-resolution spectrographs. -
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. -
The Gaia-ESO Survey: Membership Probabilities for Stars in 32 Open Clusters from 3D Kinematics
MNRAS 496, 4701–4716 (2020) doi:10.1093/mnras/staa1749 Advance Access publication 2020 June 19 The Gaia-ESO Survey: membership probabilities for stars in 32 open clusters from 3D kinematics R. J. Jackson,1‹ R. D. Jeffries,1‹ N. J. Wright,1 S. Randich,2 G. Sacco,2 E. Pancino ,2 T. Cantat-Gaudin,3 G. Gilmore,4 A. Vallenari,5 T. Bensby,6 A. Bayo,7,10 M. T. Costado,8 E. Franciosini,2 A. Gonneau,4 A. Hourihane,4 J. Lewis,4 L. Monaco,9 L. Morbidelli2 and C. Worley4 Downloaded from https://academic.oup.com/mnras/article/496/4/4701/5859956 by Universidad Andres Bello user on 27 August 2021 1Astrophysics Group, Keele University, Keele, Staffordshire ST5 5BG, UK 2INAF – Osservatorio Astrofisco di Arcetri, Largo E. Fermi, 5, I-50125 Firenze, Italy 3Institut de Ciencies` del Cosmos, Universitat de Barcelona (IEEC-UB), Mart´ı i Franques` 1, E-08028 Barcelona, Spain 4Institute of Astronomy, Cambridge University, Madingley Road, Cambridge CB3 0H, UK 5INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy 6Lund Observatory, Department of Astronomy and Theoretical Physics, Box 43, SE-221 00 Lund, Sweden 7Instituto de F´ısica y Astronom´ıa, Facultad de Ciencias, Universidad de Valpara´ıso, Av. Gran Bretana˜ 1111, 5030 Casilla, Valpara´ıso, Chile 8Departamento de Didactica,´ Universidad de Cadiz,´ E-11519 Puerto Real, Cadiz,´ Spain 9Departamento de Ciencias Fisicas, Universidad Andres Bello, Fernandez Concha 700, Las Condes, Santiago, Chile 10Nucleo´ Milenio Formacion´ Planetaria - NPF, Universidad de Valpara´ı Avenida Errazuriz´ 1834, Valpara´ıso, Chile Accepted 2020 June 12. -
Arxiv:0809.1275V2
How eccentric orbital solutions can hide planetary systems in 2:1 resonant orbits Guillem Anglada-Escud´e1, Mercedes L´opez-Morales1,2, John E. Chambers1 [email protected], [email protected], [email protected] ABSTRACT The Doppler technique measures the reflex radial motion of a star induced by the presence of companions and is the most successful method to detect ex- oplanets. If several planets are present, their signals will appear combined in the radial motion of the star, leading to potential misinterpretations of the data. Specifically, two planets in 2:1 resonant orbits can mimic the signal of a sin- gle planet in an eccentric orbit. We quantify the implications of this statistical degeneracy for a representative sample of the reported single exoplanets with available datasets, finding that 1) around 35% percent of the published eccentric one-planet solutions are statistically indistinguishible from planetary systems in 2:1 orbital resonance, 2) another 40% cannot be statistically distinguished from a circular orbital solution and 3) planets with masses comparable to Earth could be hidden in known orbital solutions of eccentric super-Earths and Neptune mass planets. Subject headings: Exoplanets – Orbital dynamics – Planet detection – Doppler method arXiv:0809.1275v2 [astro-ph] 25 Nov 2009 Introduction Most of the +300 exoplanets found to date have been discovered using the Doppler tech- nique, which measures the reflex motion of the host star induced by the planets (Mayor & Queloz 1995; Marcy & Butler 1996). The diverse characteristics of these exoplanets are somewhat surprising. Many of them are similar in mass to Jupiter, but orbit much closer to their 1Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Rd. -
A Photometric and Spectroscopic Study of the Southern Open Clusters Pismis 18, Pismis 19, Ngc 6005, and Ngc 6253 Andre S E
THE ASTRONOMICAL JOURNAL, 116:801È812, 1998 August ( 1998. The American Astronomical Society. All rights reserved. Printed in U.S.A. A PHOTOMETRIC AND SPECTROSCOPIC STUDY OF THE SOUTHERN OPEN CLUSTERS PISMIS 18, PISMIS 19, NGC 6005, AND NGC 6253 ANDRE S E. PIATTI1,2 AND JUAN J. CLARIA 2 Observatorio Astrono mico, Universidad Nacional de Co rdoba, Laprida 854, 5000 Co rdoba, Argentina; andres=oac.uncor.edu, claria=oac.uncor.edu EDUARDO BICA2 Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, C.P. 15051, Porto Alegre, 91500-970, RS, Brazil; bica=if.ufrgs.br DOUG GEISLER Kitt Peak National Observatory, National Optical Astronomy Observatories, P.O. Box 26732, Tucson, AZ 85726; doug=noao.edu AND DANTE MINNITI Lawrence Livermore National Laboratory, L-413, P.O. Box 808, Livermore, CA 94550; dminniti=igpp.llnl.gov Received 1997 October 3; revised 1998 April 24 ABSTRACT CCD observations in the B, V , and I passbands have been used to generate color-magnitude diagrams (CMDs) for the southern open cluster candidates Pismis 18, Pismis 19, and NGC 6005, as well as for the old open cluster NGC 6253. The sample consists of about 1550 stars reaching down to V D 19 mag. From analysis of the CMDs, the physical reality of the three cluster candidates is conÐrmed and their reddening, distance, and age are derived, as well as those of NGC 6253. In addition, integrated spectra for Pismis 18, Pismis 19, and NGC 6253 covering a range from 3500 to 9200A were obtained. The reddening, age, and metallicity of these three clusters were derived from Balmer and Ca II triplet equiva- lent widths by comparing the observed spectra with those of template clusters. -
Open Clusters in Gaia
Sede Amministrativa: Università degli Studi di Padova Dipartimento di Fisica e Astronomia “G. Galilei” Corso di Dottorato di Ricerca in Astronomia Ciclo XXX OPEN CLUSTERS IN GAIA ERA Coordinatore: Ch.mo Prof. Giampaolo Piotto Supervisore: Dr.ssa Antonella Vallenari Dottorando: Francesco Pensabene i Abstract Context. Open clusters (OCs) are optimal tracers of the Milky Way disc. They are observed at every distance from the Galactic center and their ages cover the entire lifespan of the disc. The actual OC census contain more than 3000 objects, but suffers of incom- pleteness out of the solar neighborhood and of large inhomogeneity in the parameter deter- minations present in literature. Both these aspects will be improved by the on-going space mission Gaia . In the next years Gaia will produce the most precise three-dimensional map of the Milky Way by surveying other than 1 billion of stars. For those stars Gaia will provide extremely precise measure- ment of proper motions, parallaxes and brightness. Aims. In this framework we plan to take advantage of the first Gaia data release, while preparing for the coming ones, to: i) move the first steps towards building a homogeneous data base of OCs with the high quality Gaia astrometry and photometry; ii) build, improve and test tools for the analysis of large sample of OCs; iii) use the OCs to explore the prop- erties of the disc in the solar neighborhood. Methods and Data. Using ESO archive data, we analyze the photometry and derive physical parameters, comparing data with synthetic populations and luminosity functions, of three clusters namely NGC 2225, NGC 6134 and NGC 2243. -
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). -
On the Metallicity of Open Clusters III
A&A 585, A150 (2016) Astronomy DOI: 10.1051/0004-6361/201526370 & c ESO 2016 Astrophysics On the metallicity of open clusters III. Homogenised sample M. Netopil1, E. Paunzen1, U. Heiter2, and C. Soubiran3 1 Department of Theoretical Physics and Astrophysics, Masaryk University, Kotlárskᡠ2, 611 37 Brno, Czech Republic e-mail: [email protected] 2 Institutionen för fysik och astronomi, Uppsala universitet, Box 516, 751 20 Uppsala, Sweden 3 Université de Bordeaux − CNRS, LAB − UMR 5804, BP 89, 33270 Floirac, France Received 21 April 2015 / Accepted 20 November 2015 ABSTRACT Context. Open clusters are known as excellent tools for various topics in Galactic research. For example, they allow accurately tracing the chemical structure of the Galactic disc. However, the metallicity is known only for a rather low percentage of the open cluster population, and these values are based on a variety of methods and data. Therefore, a large and homogeneous sample is highly desirable. Aims. In the third part of our series we compile a large sample of homogenised open cluster metallicities using a wide variety of different sources. These data and a sample of Cepheids are used to investigate the radial metallicity gradient, age effects, and to test current models. Methods. We used photometric and spectroscopic data to derive cluster metallicities. The different sources were checked and tested for possible offsets and correlations. Results. In total, metallicities for 172 open cluster were derived. We used the spectroscopic data of 100 objects for a study of the radial metallicity distribution and the age-metallicity relation. We found a possible increase of metallicity with age, which, if confirmed, would provide observational evidence for radial migration. -
51-4169, Advance Access Publication March 2017
Research Archive Citation for published version: O. M. Ivanyuk, J. S. Jenkins, Ya. V. Pavlenko, H. R. A. Jones, and D. J. Pinfield, ‘The metal-rich abundance pattern – spectroscopic properties and abundances for 107 main- sequence stars’, Monthly Notices of the Royal Astronomical Society, Vol. 468, pp. 4151-4169, advance access publication March 2017. DOI: http://dx.doi.org/10.1093/mnras/stx647 Document Version: This is the Published Version. Copyright and Reuse: © 2017 The Author(s). Content in the UH Research Archive is made available for personal research, educational, and non-commercial purposes only. Unless otherwise stated, all content is protected by copyright, and in the absence of an open license, permissions for further re-use should be sought from the publisher, the author, or other copyright holder. Enquiries If you believe this document infringes copyright, please contact the Research & Scholarly Communications Team at [email protected] MNRAS 468, 4151–4169 (2017) doi:10.1093/mnras/stx647 Advance Access publication 2017 March 16 The metal-rich abundance pattern – spectroscopic properties and abundances for 107 main-sequence stars O. M. Ivanyuk,1‹ J. S. Jenkins,2 Ya. V. Pavlenko,1,3 H. R. A. Jones3 and D. J. Pinfield3 1Main Astronomical Observatory, National Academy of Sciences of Ukraine, Holosiyiv Wood, UA-03680 Kyiv, Ukraine 2Departamento de Astronom´ıa, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago, 7591245, Chile 3Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB, UK Accepted 2017 March 14. Received 2017 March 14; in original form 2015 November 3 ABSTRACT We report results from the high-resolution spectral analysis of the 107 metal-rich (mostly [Fe/H] ≥ 7.67 dex) target stars from the Calan–Hertfordshire Extrasolar Planet Search pro- gramme observed with HARPS.