Mark's Power Peek 2007: a Daily Astrological Companion by Mark S
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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. -
Planetary Companions Around the K Giant Stars 11 Ursae Minoris and HD 32518
A&A 505, 1311–1317 (2009) Astronomy DOI: 10.1051/0004-6361/200911702 & c ESO 2009 Astrophysics Planetary companions around the K giant stars 11 Ursae Minoris and HD 32518 M. P. Döllinger1, A. P. Hatzes2, L. Pasquini1, E. W. Guenther2, and M. Hartmann2 1 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany e-mail: [email protected] 2 Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany Received 22 January 2009 / Accepted 10 August 2009 ABSTRACT Context. 11 UMi and HD 32518 belong to a sample of 62 K giant stars that has been observed since February 2004 using the 2m Alfred Jensch telescope of the Thüringer Landessternwarte (TLS) to measure precise radial velocities (RVs). Aims. The aim of this survey is to investigate the dependence of planet formation on the mass of the host star by searching for plane- tary companions around intermediate-mass giants. Methods. An iodine absorption cell was used to obtain accurate RVs for this study. Results. Our measurements reveal that the RVs of 11 UMi show a periodic variation of 516.22 days with a semiamplitude of −1 −7 K = 189.70 m s . An orbital solution yields a mass function of f (m) = (3.608 ± 0.441) × 10 solar masses (M) and an eccentricity of e = 0.083 ± 0.03. The RV curve of HD 32518 shows sinusoidal variations with a period of 157.54 days and a semiamplitude of −1 −8 K = 115.83 m s . An orbital solution yields an eccentricity, e = 0.008 ± 0.03 and a mass function, f (m) = (2.199 ± 0.235) × 10 M. -
Arxiv:2001.10147V1
Magnetic fields in isolated and interacting white dwarfs Lilia Ferrario1 and Dayal Wickramasinghe2 Mathematical Sciences Institute, The Australian National University, Canberra, ACT 2601, Australia Adela Kawka3 International Centre for Radio Astronomy Research, Curtin University, Perth, WA 6102, Australia Abstract The magnetic white dwarfs (MWDs) are found either isolated or in inter- acting binaries. The isolated MWDs divide into two groups: a high field group (105 − 109 G) comprising some 13 ± 4% of all white dwarfs (WDs), and a low field group (B < 105 G) whose incidence is currently under investigation. The situation may be similar in magnetic binaries because the bright accretion discs in low field systems hide the photosphere of their WDs thus preventing the study of their magnetic fields’ strength and structure. Considerable research has been devoted to the vexed question on the origin of magnetic fields. One hypothesis is that WD magnetic fields are of fossil origin, that is, their progenitors are the magnetic main-sequence Ap/Bp stars and magnetic flux is conserved during their evolution. The other hypothesis is that magnetic fields arise from binary interaction, through differential rotation, during common envelope evolution. If the two stars merge the end product is a single high-field MWD. If close binaries survive and the primary develops a strong field, they may later evolve into the arXiv:2001.10147v1 [astro-ph.SR] 28 Jan 2020 magnetic cataclysmic variables (MCVs). The recently discovered population of hot, carbon-rich WDs exhibiting an incidence of magnetism of up to about 70% and a variability from a few minutes to a couple of days may support the [email protected] [email protected] [email protected] Preprint submitted to Journal of LATEX Templates January 29, 2020 merging binary hypothesis. -
Determination of Stellar Parameters for M-Dwarf Stars: the NIR Approach
Determination of stellar parameters for M-dwarf stars: the NIR approach by Daniel Thaagaard Andreasen A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Departamento de Fisica e Astronomia University of Porto c Copyright 2017 by Daniel Thaagaard Andreasen Dedication To Linnea, Henriette, Rico, and Else For always supporting me ii Acknowledgements When doing a PhD it is important to remember it is more a team effort than the work of an individual. This is something I learned quickly during the last four years. Therefore there are several people I would like to thank. First and most importantly are my two supervisors, Sérgio and Nuno. They were after me in the beginning of my studies because I was too shy to ask for help; something that I quickly learned I needed to do. They always had their door open for me and all my small questions. It goes without saying that I am thankful for all their guidance during my studies. However, what I am most thankful for is the freedom I have had to explorer paths and ideas on my own, and with them safely on the sideline. This sometimes led to failures and dead ends, but it make me grow as a researcher both by learning from my mistake, but also by prioritising my time. When I thank Sérgio and Nuno, my official supervisors, I also have to thank Elisa. She has been my third unofficial supervisor almost from the first day. Although she did not have any experience with NIR spectroscopy, she was never afraid of giving her opinion and trying to help. -
Dwarf Galaxies of the Local Group Offer the Best Opportunity to Study a Representative Sample of These Important, but by Nature, Inconspicuous Galaxies in Detail
DWARF GALAXIES OF THE LOCAL GROUP Mario Mateo KEY WORDS: Stellar Populations, Local Group Galaxies, Photometry, Galaxy Formation, Spectroscopy, Dark Matter, Interstellar Medium Shortened Title: LOCAL GROUP DWARFS Send Proofs To: Mario Mateo Department of Astronomy; University of Michigan Ann Arbor, MI 48109-1090 Phone: 313 936-1742; Fax: 313 763-6317 Email: [email protected] ABSTRACT The Local Group (LG) dwarf galaxies offer a unique window to the detailed properties of the most common type of galaxy in the Universe. In this review, I update the census of LG dwarfs based on the most recent distance and radial velocity determinations. I then discuss the detailed properties of this sample, including (a) the integrated photometric parameters and optical structures of these galaxies, (b) the content, nature and distribution of their ISM, (c) their heavy-element abundances derived from both stars and nebulae, (d) the arXiv:astro-ph/9810070v1 5 Oct 1998 complex and varied star-formation histories of these dwarfs, (e) their internal kinematics, stressing the relevance of these galaxies to the dark-matter problem and to alternative interpretations, and (f) evidence for past, ongoing and future interactions of these dwarfs with other galaxies in the Local Group and beyond. To complement the discussion and to serve as a foundation for future work, I present an extensive set of basic observational data in tables that summarize much of what we know, and what we still do not know, about these nearby dwarfs. Our understanding of these galaxies has grown impressively in the past decade, but fundamental puzzles remain that will keep the Local Group at the forefront of galaxy evolution studies for some time. -
CONSTELLATION URSA MINOR, the LITTLE BEAR Ursa Minor
CONSTELLATION URSA MINOR, THE LITTLE BEAR Ursa Minor (Latin: "Smaller She-Bear", to contrast with Ursa Major), also known as the Little Bear, is a constellation in the northern sky. Like the Great Bear, the tail of the Little Bear may also be seen as the handle of a ladle, hence the North American name, Little Dipper. It has seven main stars with four in its bowl, like its partner the Big Dipper. It was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Ursa Minor has traditionally been important for navigation, particularly by mariners, because of Polaris (at the end of the tail) being the North Star. Alpha Ursae Minoris, better known as Polaris, is the brightest star in the constellation, is a yellow-white supergiant and the brightest Cepheid variable star in the night sky, ranging from an apparent magnitude of 1.97 to 2.00. Beta Ursae Minoris, also known as Kochab, is an aging star that has swollen and cooled to become an orange giant with an apparent magnitude of 2.08, only slightly fainter than Polaris. Gamma Ursae Minoris, magnitude 3 and Kochab have been called the "guardians of the pole star". Planets have been detected orbiting four of the stars, including Kochab. The constellation also contains an isolated neutron star—Calvera—and H1504+65, the hottest white dwarf yet discovered, with a surface temperature of 200,000 K. HISTORY AND MYTHOLOGY In the Babylonian star catalogues, Ursa Minor was known as the Wagon of Heaven, Damkianna. -
Quantization of Planetary Systems and Its Dependency on Stellar Rotation Jean-Paul A
Quantization of Planetary Systems and its Dependency on Stellar Rotation Jean-Paul A. Zoghbi∗ ABSTRACT With the discovery of now more than 500 exoplanets, we present a statistical analysis of the planetary orbital periods and their relationship to the rotation periods of their parent stars. We test whether the structure of planetary orbits, i.e. planetary angular momentum and orbital periods are ‘quantized’ in integer or half-integer multiples with respect to the parent stars’ rotation period. The Solar System is first shown to exhibit quantized planetary orbits that correlate with the Sun’s rotation period. The analysis is then expanded over 443 exoplanets to statistically validate this quantization and its association with stellar rotation. The results imply that the exoplanetary orbital periods are highly correlated with the parent star’s rotation periods and follow a discrete half-integer relationship with orbital ranks n=0.5, 1.0, 1.5, 2.0, 2.5, etc. The probability of obtaining these results by pure chance is p<0.024. We discuss various mechanisms that could justify this planetary quantization, such as the hybrid gravitational instability models of planet formation, along with possible physical mechanisms such as inner discs magnetospheric truncation, tidal dissipation, and resonance trapping. In conclusion, we statistically demonstrate that a quantized orbital structure should emerge naturally from the formation processes of planetary systems and that this orbital quantization is highly dependent on the parent stars rotation periods. Key words: planetary systems: formation – star: rotation – solar system: formation 1. INTRODUCTION The discovery of now more than 500 exoplanets has provided the opportunity to study the various properties of planetary systems and has considerably advanced our understanding of planetary formation processes. -
1985Aj 90.22210 the Astronomical Journal
THE ASTRONOMICAL JOURNAL VOLUME 90, NUMBER 11 NOVEMBER 1985 90.22210 THE URSA MINOR DWARF GALAXY: STILL AN OLD STELLAR SYSTEM Edward W. Olszewski^ Steward Observatory, University of Arizona, Tucson, Arizona 85721 1985AJ and Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, Victoria, British Columbia V8X 4M6, Canada Marc AARONSONa) Steward Observatory, University of Arizona, Tucson, Arizona 85721 Received 25 March 1985; revised 5 August 1985 ABSTRACT We have constructed a color-magnitude diagram of the Ursa Minor dwarf spheroidal to = 24.8 mag from charged-coupled device (CCD) observations with the Kitt Peak 4 m telescope. The main-sequence turnoff is easily visible. Fits to evolutionary isochrones and the globular M92 indicate that Ursa Minor has an age and metal abundance very similar to that of the latter cluster. No evidence for stars younger than about 16 billion years is seen, with the possible exception of approximately 20 stars believed to be blue stragglers. Ursa Minor is therefore an extreme-age galaxy, unlike superficially similar objects such as the Carina dwarf. Indeed, Ursa Minor may be the only outer-halo spheroidal whose stellar content lives up to the classical ideals of a Population II system. A distance modulus of (m — Af )0 = 19.0 mag is derived from a sliding fit to the M92 ridge lines. However, this modulus is uncertain by ~0.1 mag, for the horizontal branch in our color-magnitude diagram is poorly populated. The ratio of blue stragglers to anomalous Cepheids in Ursa Minor is estimated to be ~ 100, a number that may provide an impor- tant constraint on binary models for the origin of these stars. -
Astronomy of the Northern Sky— - a Sky Quest on Star Lives - Larry Krumenaker
Astronomy of the Northern Sky— - A Sky Quest on Star Lives - Larry Krumenaker There is no topic so vital to an astronomy course as the life of a star like our Sun. It ties in to so many questions: How old is our planet? Where do we come from? What is the future of the solar sys- tem? Why do all the stars look different in brightness and/or color? We have looked at parts of this story in issues past, in this column and in some other TCA articles. Here we begin to put all the previous col- umns of information together into the full story of what we are, where we came from, where we are, and where are we going. This is going to be somewhat like a Sky Quest, a search for objects in the northern sky (see Figure 1), instead of a Web Quest, with the story and sky info (the latter in this blue color) moving along together. Non-stellar objects are labeled with catalog abbreviations and numbers: M=Messier’s Catalog, NGC is the New General Catalog, and IC means Index Catalog, a follow-up to the NGC. We’ve covered star names and spectral classes in earlier TCA issues, except for HD, the Henry Draper catalog. In this Sky Quest, we shall talk about stellar evolution, the birth, life and death of a star like our Sun, and finding the representative stages up in the northern sky. Figure 2. The stages in the life cycle of the Sun. Our Past The basics of stellar evolution are the universe is the ultimate in recycling. -
Extrasolar Planets and Their Host Stars
Kaspar von Braun & Tabetha S. Boyajian Extrasolar Planets and Their Host Stars July 25, 2017 arXiv:1707.07405v1 [astro-ph.EP] 24 Jul 2017 Springer Preface In astronomy or indeed any collaborative environment, it pays to figure out with whom one can work well. From existing projects or simply conversations, research ideas appear, are developed, take shape, sometimes take a detour into some un- expected directions, often need to be refocused, are sometimes divided up and/or distributed among collaborators, and are (hopefully) published. After a number of these cycles repeat, something bigger may be born, all of which one then tries to simultaneously fit into one’s head for what feels like a challenging amount of time. That was certainly the case a long time ago when writing a PhD dissertation. Since then, there have been postdoctoral fellowships and appointments, permanent and adjunct positions, and former, current, and future collaborators. And yet, con- versations spawn research ideas, which take many different turns and may divide up into a multitude of approaches or related or perhaps unrelated subjects. Again, one had better figure out with whom one likes to work. And again, in the process of writing this Brief, one needs create something bigger by focusing the relevant pieces of work into one (hopefully) coherent manuscript. It is an honor, a privi- lege, an amazing experience, and simply a lot of fun to be and have been working with all the people who have had an influence on our work and thereby on this book. To quote the late and great Jim Croce: ”If you dig it, do it. -
Theory of Stellar Atmospheres
© Copyright, Princeton University Press. No part of this book may be distributed, posted, or reproduced in any form by digital or mechanical means without prior written permission of the publisher. EXTENDED BIBLIOGRAPHY References [1] D. Abbott. The terminal velocities of stellar winds from early{type stars. Astrophys. J., 225, 893, 1978. [2] D. Abbott. The theory of radiatively driven stellar winds. I. A physical interpretation. Astrophys. J., 242, 1183, 1980. [3] D. Abbott. The theory of radiatively driven stellar winds. II. The line acceleration. Astrophys. J., 259, 282, 1982. [4] D. Abbott. The theory of radiation driven stellar winds and the Wolf{ Rayet phenomenon. In de Loore and Willis [938], page 185. Astrophys. J., 259, 282, 1982. [5] D. Abbott. Current problems of line formation in early{type stars. In Beckman and Crivellari [358], page 279. [6] D. Abbott and P. Conti. Wolf{Rayet stars. Ann. Rev. Astr. Astrophys., 25, 113, 1987. [7] D. Abbott and D. Hummer. Photospheres of hot stars. I. Wind blan- keted model atmospheres. Astrophys. J., 294, 286, 1985. [8] D. Abbott and L. Lucy. Multiline transfer and the dynamics of stellar winds. Astrophys. J., 288, 679, 1985. [9] D. Abbott, C. Telesco, and S. Wolff. 2 to 20 micron observations of mass loss from early{type stars. Astrophys. J., 279, 225, 1984. [10] C. Abia, B. Rebolo, J. Beckman, and L. Crivellari. Abundances of light metals and N I in a sample of disc stars. Astr. Astrophys., 206, 100, 1988. [11] M. Abramowitz and I. Stegun. Handbook of Mathematical Functions. (Washington, DC: U.S. Government Printing Office), 1972. -
XIII Publications, Presentations
XIII Publications, Presentations 1. Refereed Publications Bakunina, I. A., Abramov-maximov, V. E., Nakariakov, V. M., Lesovoy, S. V., Soloviev, A. A., Tikhomirov, Y. V., Melnikov, V. F., Shibasaki, K., Abramov-Maximov, V. E., Efremov, V. I., Parfinenko, L. D., Solov'ev, Nagovitsyn, Y. A., Averina, E. L.: 2013, Long-Period Oscillations of A. A., Shibasaki, K.: 2013, Long-period oscillations of sunspots Sunspots by NoRH and SSRT Observations, PASJ, 65, S13. according to simultaneous ground-based and space observations, Batista, V., Beaulieu, J.-P., Gould, A., Bennet, D. P., Yee, J. C., Fukui, A., Geomag. Aeron., 53, 909-912. Gaudi, B. S., Sumi, T., Udalski, A.: 2014, MOA-2011-BLG-293Lb: First Abramov-maximov, V. E., Efremov, V. I., Parfinenko, L. D., Solov'ev, A. Microlensing Planet Possibly in the Habitable Zone, ApJ, 780, 54. A., Shibasaki, K.: 2013, Long-Term Oscillations of Sunspots from Baty, H., Pétri, J., Zenitani, S.: 2013, Explosive reconnection of double Simultaneous Observations with the Nobeyama Radioheliograph and tearing modes in relativistic plasmas: application to the Crab flare, Solar Dynamics Observatory, PASJ, 65, S12. MNRAS, 436, L20-L24. Abu-Zayyad, T., et al. including Oshima, A.: 2013, Correlations Bendek, E. A., Guyon, O., Ammons, S. M., Belikov, R.: 2013, Laboratory of the Arrival Directions of Ultra-High Energy Cosmic Rays Demonstration of Astrometric Compensation Using a Diffractive with Extragalactic Objects as Observed by the Telescope Array Pupil, PASP, 125, 1212-1225. Experiment, ApJ, 777, 88. Bersten, M. C., Tanaka, M., Tominaga, N., Benvenuto, O. G., Nomoto, Abu-Zayyad, T., et al. including Oshima, A.: 2013, Upper limit on the K.: 2013, Early UV/Optical Emission of The Type Ib SN 2008D, ApJ, flux of photons with energies above 1019 eV using the Telescope 767, 143.