DOCSLIB.ORG

San Jose Astronomical Association Membership Form P.O

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
San Jose Astronomical Association Membership Form P.O EPHEMERIS November 2011 SJAA Activities Calendar The (Unusual) Making of a Jim Van Nuland Planet November p.m, 5% moon sets 6:30 p.m. Henry Paul Kohlmiller 4 Houge Park star party. Sunset 6:07 Coe Park’s “Astronomy” lot has been When a star of sufficient size explodes p.m, 74% moon sets 2:56 a.m. Star reserved. in a nova, the remnant can be a pulsar. party hours: 7:00 until 10:00 p.m. December Pulsars are neutron stars, stars that 5 Houge Park star party. Sunset 6:06 2 Houge Park star party. Sunset 4:50 are so dense that atoms are crushed p.m, 81% moon sets 3:52 a.m. Part p.m, 57% moon sets 12:44 a.m. Star to the point that only neutrons exist. of the Bay Area Astronomy & Sci- party hours: 7:00 until 10:00 p.m. Imagine shrinking the size of the sun ence Festival. 10 General Meeting. Board meeting at to the size of the city of San Jose. The 6 DST ends at 2 a.m. Retard clocks to 6:30; General Meeting at 8:00. Our pulses come from beams that come 1 a.m. speaker is Dr. Bruce Margon, on out from the magnetic poles. These beams of (typically) X-ray or radio 12 General Meeting. Board meeting “Glimpsing the Edge of the Universe: electromagnetic radiation sweep around at 6:30; General Meeting at 8:00. Results from the Hubble Space Tele- as the star rotates. So from Earth they Our speaker is Dr. Lynn Rothschild, scope”. appear to be flashes. on Life at the Edge: Life in Extreme 16 Astronomy Class at Houge Park. 7:00 Environments on Earth and the p.m. The topic: The Sun, planets and Pulsars are so consistent they are as Search for Life in the Universe. minor solar system objects. accurate as atomic time clocks. This 13 Astronomical Swap Meet. Noon to 16 Houge Park star party. Sunset 4:52 means that when something perturbs late afternoon. p.m, 60% moon rises 11:23 p.m. Star them, like another object orbiting the 18 Astronomy Class at Houge Park. party hours: 7:00 until 10:00 p.m. pulsar, it is easy to characterize what 7:00 p.m. The topic: Amateur 17 Dark-Sky weekend. Sunset 4:52 p.m, must be causing the blips in the data. telescope making, why, how and 33% moon rises 1:33 a.m. Of course, many stars are binary stars. where. With members of the 24 Dark-Sky weekend. Sunset 4:55 p.m, What happens to the companion star? Chabot Science Center’s Telescope 5% moon sets 6:30 p.m. Henry Coe Well, one outcome is that the mass of Maker’s Workshop. Park’s “Astronomy” lot has been the second star gets pulled bit-by-bit 18 Houge Park star party. Sunset 4:56 reserved. onto the neutron star. These are called p.m, 44% moon rises 12:25 a.m. 30 Houge Park star party. Sunset 4:59 “Black Widow” pulsars. Now, think Star party hours: 7:00 until 10:00 p.m, 40% moon sets 11:30 p.m. Star about what that kind of ablation means. p.m. party hours: 7:00 until 10:00 p.m. The companion star gets smaller and 19 Houge Park star party. Star party smaller. It might have started out as a for students of Live Oak Academy, The Board of Directors meets before sun-like star but it loses mass. Eventually Conducted by the School star each general meeting at 6:30 p.m. All Continued on page 2 party team. Others welcome too. are welcome to attend. 19 Dark-Sky weekend. Sunset 4:55 24 hour news and information hotline: p.m, 33% moon rises 1:33 a.m. (408) 559-1221 26 Dark-Sky weekend. Sunset 4:52 http://www.sjaa.net Copyright © 2011 San Jose Astronomical Association, Inc. Volume 22 Number 11 Official publication of the San Jose Astronomical Association, November 2011 The (Unusual) Making of a Planet planetary system. On the other hand, have companions and some do not. The Continued from page 1 these strange exoplanets are the lowest distinction, as you might expect, is how it will no longer have the mass necessary mass exoplanets discovered to date, as close the companion is when it starts to continue nuclear fusion. Then it gets small as the Moon. losing mass to the larger star. If it is far even smaller until it becomes ... Jupiter! enough away, say several solar radii, the Or at least something about that size. Although the planetary companion companion will survive. of PSRJ1719-1438 is about the size of In Science magazine (Sept. 23, 2011), Jupiter, its mass is about 20 times that of But should this pulsar companion researchers describe finding a planet Jupiter. This suggests it is not made up be considered a planet at all. You will around a pulsar (PSR J1719-1438) that of hydrogen and helium, the best guess recall the 2006 attempt to restrict the is spinning very fast - one rotation in 6 is carbon. At these pressures, the carbon definition of “planet’ which excluded milliseconds or less. Its companion can would be in a crystallized form, hence Pluto, to the horror of school kids be detected by perturbations in the this planet’s nickname “The Diamond around the world. The article for Science pulses that can be detected on Earth. As Planet”. was written by Frederic Rasio from a star the companion probably got to be Northwestern. He says “The lesson here a carbon white dwarf. In Science magazine, one article is a is perhaps that, as our rapidly improving summarization of a more technical astronomical instruments make it Planets around pulsars are not new. paper. In this case the technical paper is possible to detect objects of smaller and The very first exoplanets were detected written by M. Bailes et. al. (where the “al” smaller mass in distant and, sometimes, around pulsar PSR B1257+12. They are consists of 17 coauthors). A question very exotic environments, any narrow often considered to be “not real planets” raised in the technical paper is why definition of planet will soon become because of the strange nature of their should some millisecond pulsars (MSP) obsolete.” Contact (The Reel and the Real): Humanity’s Search for Extra-terrestrial Intelligence A film and talk with Dr. Jill Tarter of the SETI Institute Wednesday evening, Nov. 2, at 6 - 9:30 p.m. Andrew Fraknoi Directions to Houge Park McKenna Theater at San Francisco State University, Houge (rhymes with “Yogi”) Park is in San Jose, Holloway Avenue and Tapia Drive, San Francisco, CA near Campbell and Los Gatos. From Hwy. 17, take the 94132 (For a map and parking links, see: http://www.sfsu. Camden Avenue exit. Go east 0.4 miles, and turn right edu/~sfsumap/) at the light, onto Bascom Avenue. At the next light, turn left onto Woodard Road. At the first stop sign, turn right Co-sponsored by the SF State Department of Physics onto Twilight Drive. Go three blocks, cross Sunrise Drive, and Astronomy. Free and Open to the Public (seats are then turn left into the park. available first come, first served) From Hwy. 85, take the Bascom Avenue exit. Go north, and turn right at the first traffic light, onto White Join astronomer Jill Tarter, whose work and life was a key Oaks Road. At the first stop sign, turn left onto Twilight model for the character Jodie Foster plays in the film Drive. You will now be passing the park. Turn right at the Contact, for a very special evening of science fiction and first driveway, into the parking lot. cutting-edge science. We will screen the full-length film about the discovery of intelligent life among the stars, and then hear Dr. Tarter discuss her ongoing work at the SETI Institute to find radio signals from alien civilizations. After her film and the talk, there will be time for questions from the audience. SJAA EPHEMERIS Page 2 November 2011 The Shallow Sky Flooded craters Akkana Peck Daylight Savings Time ends on while you’re in the area, just south of low for anyone but the most dedicated November 6: it’s time to set your clocks there is Capuanus, the “bear paw” (Rukl Plutocrat. back again (those that aren’t set by chart 63), another interesting filled-in radio or internet signals). So we’ll get a “ghost crater”. It’s called the “bear paw” But the real star of November nights little more evening time to observe this because of the claws extending from it. is Jupiter. I wrote last month that this month. Take a look — you’ll see! should be an excellent Jupiter year (weather permitting, of course). The And that’s handy, because Mercury Another excellent flooded lunar crater giant planet is only a few days past hangs in the early evening sky most of is Fracastorius (Rukl chart 58), a lovely opposition as we move into November, the month — and it’s not alone there. It horseshoe crater rim with a smoothly and since it’s relatively far north — sits near Venus for the first two weeks, filled floor. It makes a nice sight at transiting as high as 65 degrees — with Antares joining the pair on the 9th sunrise with its neighbor Piccolomini. maybe some of you were able to show it and 10th. Try them on Halloween or on November to the kiddies on Halloween.
Load more

Recommended publications
  • Spectroscopic Orbits of Three Dwarf Barium Stars
    SPECTROSCOPIC ORBITS OF THREE DWARF BARIUM STARS By P. L. North1, A. Jorissen2, A. Escorza2;3, B. Miszalski4;5, and J. Mikoajewska6 1Institute of Physics, Laboratory of Astrophysics, Ecole Polytechnique F´ed´erale de Lausanne (EPFL), Switzerland 2Institut d'Astronomie et d'Astrophysique, Universit´eLibre de Bruxelles, Belgium 3Instituut voor Sterrenkunde, KU Leuven, Belgium 4South African Astronomical Observatory 5Southern African Large Telescope Foundation 6N. Copernicus Astronomical Center, Polish Academy of Sciences, Warsaw, Poland Barium stars are thought to result from binary evolution in systems wide enough to allow the more massive component to reach the asymptotic giant branch and eventually become a CO white dwarf. While Ba stars were initially known only among giant or subgiant stars, some were subsequently discovered also on the main sequence (and known as dwarf Ba stars). We provide here the orbital parameters of three dwarf Ba stars, completing the sample of 27 orbits published recently by Escorza et al. with these three southern targets. We show that these new orbital parameters are consistent with those of other dwarf Ba stars. Introduction Barium stars are not evolved enough to synthesize in their interiors and dredge up to their surface the s-process elements (including Ba) that are very abundant in their atmospheres. On the other hand, we have convincing statistical indications that they all belong to SB1-type binary systems [1] [2], and UV arXiv:2001.11319v1 [astro-ph.SR] 30 Jan 2020 observations have revealed the white
    [Show full text]
  • A Nn U a L Re P O
    2008 A NORDIC OPTICAL NN TELESCOPE U Galaxy clusters acting as gravitational lenses. A L RE P O R T NORDIC OPTICAL TELESCOPE The Nordic Optical Telescope (NOT) is a modern 2.5-m telescope located at the Spanish Observa- torio del Roque de los Muchachos on the island of La Palma, Canarias, Spain. It is operated for the benefit of Nordic astronomy by theN ordic Optical Telescope Scientific Asso ciation (NOTSA), estab- lished by the national Research Councils of Den- mark, Finland, Norway, and Sweden, and the Uni- versity of Iceland. The chief governing body of NOTSA is the Council, which sets overall policy, approves the annual bud- gets and accounts, and appoints the Director and Astronomer-in-Charge. A Scienti fic and Technical Committee (STC) advises the Council on scientific and technical policy. An Observing Programmes Committee (OPC) of independent experts, appointed by the Council, performs peer review and scientific ranking of the observing proposals submitted. Based on the rank- Front cover: A mosaic of galaxy clusters ing by the OPC, the Director prepares the actual showing strong gravitational lensing and observing schedule. giant arcs discovered with the NOT (see p. 5). Composite images in blue and red light from the NOT, Gemini, and Subaru The Director has overall responsibility for the telescopes. Photo: H. Dahle, Oslo. operation of NOTSA, including staffing, financial matters, external relations, and long-term plan- ning. The staff on La Palma is led by the Astrono- mer-in-Charge, who has authority to deal with all matters related to the daily operation of NOT.
    [Show full text]
  • Stellar Spectral Classification of Previously Unclassified Stars Gsc 4461-698 and Gsc 4466-870" (2012)
    University of North Dakota UND Scholarly Commons Theses and Dissertations Theses, Dissertations, and Senior Projects January 2012 Stellar Spectral Classification Of Previously Unclassified tS ars Gsc 4461-698 And Gsc 4466-870 Darren Moser Grau Follow this and additional works at: https://commons.und.edu/theses Recommended Citation Grau, Darren Moser, "Stellar Spectral Classification Of Previously Unclassified Stars Gsc 4461-698 And Gsc 4466-870" (2012). Theses and Dissertations. 1350. https://commons.und.edu/theses/1350 This Thesis is brought to you for free and open access by the Theses, Dissertations, and Senior Projects at UND Scholarly Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UND Scholarly Commons. For more information, please contact [email protected]. STELLAR SPECTRAL CLASSIFICATION OF PREVIOUSLY UNCLASSIFIED STARS GSC 4461-698 AND GSC 4466-870 By Darren Moser Grau Bachelor of Arts, Eastern University, 2009 A Thesis Submitted to the Graduate Faculty of the University of North Dakota in partial fulfillment of the requirements For the degree of Master of Science Grand Forks, North Dakota December 2012 Copyright 2012 Darren M. Grau ii This thesis, submitted by Darren M. Grau in partial fulfillment of the requirements for the Degree of Master of Science from the University of North Dakota, has been read by the Faculty Advisory Committee under whom the work has been done and is hereby approved. _____________________________________ Dr. Paul Hardersen _____________________________________ Dr. Ronald Fevig _____________________________________ Dr. Timothy Young This thesis is being submitted by the appointed advisory committee as having met all of the requirements of the Graduate School at the University of North Dakota and is hereby approved.
    [Show full text]
  • I Am: Astronomy Who Is? Travel in a Path Around
    I am: Astronomy I am: Orbit Who is? travel in a path Who is? More oval in shape around the Sun than perfectly circular I am: Rotate I am: Solar system Who is? An imaginary line Who is? Spins on an axis that runs through the middle of an object I am: An axis I am: Gravity Who is? Used to measure Who is? A force that keeps distances in the solar satellites in orbit system I am: An astronomical unit I am: A nebula Who is? A rotating cloud of Who is? Mercury, Venus, dust and gas Earth & Mars I am: The inner planets I am: A crater Who is? A bowl shaped depression that forms when The smallest inner an object crashes into a Who is? surface planet I am: Mercury I am: Venus Who is? The second planet Who is? The third planet from the Sun? from the Sun I am: Earth I am: Revolve Who is? The fourth planet Who is? The path made from the Sun? during a revolution around the Sun I am: Mars I am: Asteroids Who is? Small, rocky Who is? Beyond the objects that orbit the Sun asteroid belt I am: Elliptical I am: The outer planets Who is? The Sun and all it’s Who is? So large that all satellites other planets could fit in it I am: Jupiter I am: Saturn Who is? The second largest Who is? 4 times larger than planet in the solar system Earth? I am: Uranus I am: Comets Who is? Frozen chunks of Who is? Pieces of rock or ice, gas and dust metal in space, smaller than a few hundred meters I am: Meteoroids I am: Meteor Who is? Streak of light from Who is? Meteor that hits a burning meteoroid the Earth’s surface I am: Meteorite I am: Nuclear fusion Who is? A reaction
    [Show full text]
  • Optical Counterparts of ROSAT X-Ray Sources in Two Selected Fields at Low
    Astronomy & Astrophysics manuscript no. sbg˙comsge˙ed c ESO 2018 October 16, 2018 Optical counterparts of ROSAT X-ray sources in two selected fields at low vs. high Galactic latitudes J. Greiner1, G.A. Richter2 1 Max-Planck-Institut f¨ur extraterrestrische Physik, 85740 Garching, Germany 2 Sternwarte Sonneberg, 96515 Sonneberg, Germany Received 14 October 2013 / Accepted 12 August 2014 ABSTRACT Context. The optical identification of large number of X-ray sources such as those from the ROSAT All-Sky Survey is challenging with conventional spectroscopic follow-up observations. Aims. We investigate two ROSAT All-Sky Survey fields of size 10◦× 10◦ each, one at galactic latitude b = 83◦ (26 Com), the other at b = –5◦ (γ Sge), in order to optically identify the majority of sources. Methods. We used optical variability, among other more standard methods, as a means of identifying a large number of ROSAT All- Sky Survey sources. All objects fainter than about 12 mag and brighter than about 17 mag, in or near the error circle of the ROSAT positions, were tested for optical variability on hundreds of archival plates of the Sonneberg field patrol. Results. The present paper contains probable optical identifications of altogether 256 of the 370 ROSAT sources analysed. In partic- ular, we found 126 AGN (some of them may be misclassified CVs), 17 likely clusters of galaxies, 16 eruptive double stars (mostly CVs), 43 chromospherically active stars, 65 stars brighter than about 13 mag, 7 UV Cet stars, 3 semiregular resp. slow irregular variable stars of late spectral type, 2 DA white dwarfs, 1 Am star, 1 supernova remnant and 1 planetary nebula.
    [Show full text]
  • KELT-17: a Chemically Peculiar Am Star and a Hot-Jupiter Planet
    manuscript no. saffe c 2020 July 29, 2020 KELT-17: a chemically peculiar Am star and a hot-Jupiter planet⋆ C. Saffe1, 2, 6, P. Miquelarena1, 2, 6, J. Alacoria1, 6, J. F. González1, 2, 6, M. Flores1, 2, 6, M. Jaque Arancibia4, 5, D. Calvo2, E. Jofré7, 3, 6 and A. Collado1, 2, 6 1 Instituto de Ciencias Astronómicas, de la Tierra y del Espacio (ICATE-CONICET), C.C 467, 5400, San Juan, Argentina. 2 Universidad Nacional de San Juan (UNSJ), Facultad de Ciencias Exactas, Físicas y Naturales (FCEFN), San Juan, Argentina. 3 Observatorio Astronómico de Córdoba (OAC), Laprida 854, X5000BGR, Córdoba, Argentina. 4 Instituto de Investigación Multidisciplinar en Ciencia y Tecnología, Universidad de La Serena, Raúl Bitrán 1305, La Serena, Chile 5 Departamento de Física y Astronomía, Universidad de La Serena, Av. Cisternas 1200 N, La Serena, Chile. 6 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina 7 Instituto de Astronomía, Universidad Nacional Autónoma de México, Ciudad Universitaria, CDMX, C.P. 04510, México Received xxx, xxx ; accepted xxxx, xxxx ABSTRACT Context. The detection of planets orbiting chemically peculiar stars is very scarcely known in the literature. Aims. To determine the detailed chemical composition of the remarkable planet host star KELT-17. This object hosts a hot-Jupiter planet with 1.31 MJup detected by transits, being one of the more massive and rapidly rotating planet hosts to date. We aimed to derive a complete chemical pattern for this star, in order to compare it with those of chemically peculiar stars. Methods. We carried out a detailed abundance determination in the planet host star KELT-17 via spectral synthesis.
    [Show full text]
  • Refined Chemical Abundances of Π Dra and Hr 7545 With
    International Journal of Research in Science and Technology http://www.ijrst.com (IJRST) 2017, Vol. No. 7, Issue No. III, Jul-Sep e-ISSN: 2249-0604, p-ISSN: 2454-180X REFINED CHEMICAL ABUNDANCES OF DRA AND HR 7545 WITH ATLAS12 *Doğuş Özuyar, *Aslı Elmaslı, *Şeyma Çalışkan *Department of Astronomy and Space Sciences, Ankara University, Science Faculty Ankara, Turkey ABSTRACT We present the more refined abundances of elements (C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni, Zn, Sr, Y, Zr and Ba) determined using the computationally intensive ATLAS12 atmosphere model for the metallic-line stars Dra and HR 7545. We compare the chemical abundances derived from ATLAS9 model atmosphere with those of derived from ATLAS12. The abundances are in agreement with each other, within their uncertainties. We thus state that ATLAS9 may be used for the abundance analysis of slowly rotating chemically peculiar stars, such as Dra and HR 7545. Keywords: metallic-line stars; Dra; HR 7545; chemical abundance; ATLAS9; ATLAS12) INTRODUCTION One of A-type star sub-groups, called metallic-line A-type (hereafter Am) stars, exhibits generally A-type spectral behavior with some elemental anomalies. These anomalies are typically deficiency of Sc and sometimes Ca, under-abundances in the light elements (C, O, etc.), followed by an increase in iron-peak element (Cr, Mn, Fe, Ni, etc.) abundances, and a considerably overabundances in the heavy elements, such as Sr, Y, Zr, and Ba, with respect to the solar values [1]. Another characteristic property of Am stars is their low rotational velocities compared to normal A-type stars (< 120 km s-1, [2]).
    [Show full text]
  • THE UBC-OAN PHOTOMETRIC SURVEY by FRANCOIS
    SEARCHING FOR NORTHERN ROAP STARS: THE UBC-OAN PHOTOMETRIC SURVEY By FRANCOIS CHAGNON B. Sc. (Specialise en Physique) Universite de Montreal (1996) A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF PHYSICS & ASTRONOMY We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September 1998 © FRANCOIS CHAGNON, 1998 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Physics & Astronomy The University of British Columbia 129-2219 Main Mall Vancouver, Canada V6T 1Z4 Date: Abstract Because they pulsate in multiple high-overtone p-modes, rapidly oscillating Ap stars (roAp) represent a very powerful tool to apply the techniques of asteroseismology, which can lead to the global properties and internal structure of stars. The majority of roAp stars are in the Southern Hemisphere, beyond the reach of northern observatories like CFHT and DAO, which have superb coude spectrographs that can help reveal additional modes and clues to the pulsation dynamics. To try to correct this imbalance, we began a systematic search for roAp stars in the Northern Hemisphere.
    [Show full text]
  • The Magnetic Field of the Double-Lined Spectroscopic Binary System HD 5550
    A&A 589, A47 (2016) Astronomy DOI: 10.1051/0004-6361/201527355 & c ESO 2016 Astrophysics The magnetic field of the double-lined spectroscopic binary system HD 5550? E. Alecian1; 2; 3, A. Tkachenko4, C. Neiner3, C. P. Folsom1; 2, B. Leroy3, and the BinaMIcS Collaboration 1 Univ. Grenoble Alpes, IPAG, 38000 Grenoble, France e-mail: [email protected] 2 CNRS, IPAG, 38000 Grenoble, France 3 LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195 Meudon, France 4 Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium Received 14 September 2015 / Accepted 18 December 2015 ABSTRACT Context. The origin of fossil fields in intermediate- and high-mass stars is poorly understood, as is the interplay between binarity and magnetism during stellar evolution. Thus we have begun a study of the magnetic properties of a sample of intermediate-mass and massive short-period binary systems as a function of binarity properties. Aims. This paper specifically aims to characterise the magnetic field of HD 5550, a double-lined spectroscopic binary system of intermediate mass. Methods. We gathered 25 high-resolution spectropolarimetric observations of HD 5550 using the instrument Narval. We first fitted the intensity spectra using Zeeman/ATLAS9 LTE synthetic spectra to estimate the effective temperatures, microturbulent velocities, and the abundances of some elements of both components, as well as the light ratio of the system. We then applied the multi-line least-square deconvolution (LSD) technique to the intensity and circularly polarised spectra, which provided us with mean LSD I and V line profiles.
    [Show full text]
  • Chemically Peculiar Star HR8844 Could Be a Hybrid Object 21 September 2016, by Tomasz Nowakowski
    Chemically peculiar star HR8844 could be a hybrid object 21 September 2016, by Tomasz Nowakowski "The derived abundance pattern of HR8844 strongly departs from the solar composition, which definitely shows that HR8844 is not a superficially normal early A star, but is actually another new chemically peculiar star," the researchers wrote in the paper. Chemically peculiar stars, like HR8844, are main- sequence A and B stars with unusually strong or weak lines for certain elements. Besides their chemical composition, they have magnetic fields and experience very slow rotation with an average velocity of 29 km/s, which leads to extremely sharp- lined spectra. The new findings are based on data provided by The derived elemental abundances for HR8844. Credit: the SOPHIE high-resolution echelle spectrograph Monier et al., 2016. installed on the 1.93m reflector telescope at the Haute-Provence Observatory in southeastern France. The team has analyzed the SOPHIE dataset and found that HR8844 has under- (Phys.org)—Astronomers from the Paris abundances of light elements like helium (He), Observatory in Meudon, France and the Notre carbon (C), nitrogen (N) and oxygen (O) and Dame University – Louaize in Zouk Mosbeh, overabundances of the iron-peak elements and of Lebanon, report that an A-type main-sequence star the very heavy elements such as strontium (Sr), HR8844, could be a hybrid object between two yttrium (Y), zirconium (Zr) and mercury (Hg). classes of chemically peculiar stars. The discovery was detailed in a paper published Sept. 16 on Taking into account a mild overabundance of arXiv.org. manganese (Mn), the scientists concluded that HR8844 could be a hybrid object between the Previous studies described HR8844 as a slowly HgMn stars and the Am stars.
    [Show full text]
  • Metallic-Line Stars Identified from Low Resolution Spectra of LAMOST
    Draft version April 9, 2019 Typeset using LATEX twocolumn style in AASTeX62 Metallic-Line Stars Identified from Low Resolution Spectra of LAMOST DR5 Li Qin,1, 2, 3 A-Li Luo,1, 2, 3, 4 Wen Hou,1 Yin-Bi Li,1 Shuo Zhang,1, 3 Rui Wang,1, 3 Li-Li Wang,1, 2, 3 Xiao Kong,1, 3 and Jin-Shu Han2 1Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences,Beijing 100012, China 2School of Information Management & Institute for Astronomical Science, Dezhou University, Dezhou 253023, China 3University of Chinese Academy of Sciences, Beijing 100049, China 4Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA ABSTRACT LAMOST DR5 released more than 200,000 low resolution spectra of early-type stars with S/N>50. Searching for metallic-line (Am) stars in such a large database and study of their statistical properties are presented in this paper. Six machine learning algorithms were experimented with using known Am spectra, and both the empirical criteria method(Hou et al. 2015) and the MKCLASS package(Gray et al. 2016) were also investigated. Comparing their performance, the random forest (RF) algorithm won, not only because RF has high successful rate but also it can derives and ranks features. Then the RF was applied to the early type stars of DR5, and 15,269 Am candidates were picked out. Manual identification was conducted based on the spectral features derived from the RF algorithm and verified by experts. After manual identification, 9,372 Am stars and 1,131 Ap candidates were compiled into a catalog.
    [Show full text]
  • Absolute Magnitudes of Chemically Peculiar Stars
    239 ABSOLUTE MAGNITUDES OF CHEMICALLY PECULIAR STARS 1 2 1 3 3 1 P. North , C. Jaschek , B. Hauck , F. Figueras ,J.Torra ,M.Kunzli 1 Institut d'Astronomie de l'Universit e de Lausanne, CH-1290 Chavannes-des-Bois, Switzerland 2 Observatoire de Strasb ourg, 11 rue de l'Universit e, F-67000 Strasb ourg, France 3 Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Spain ABSTRACT Table 1. Groups of CP stars with their approximate char- acteristics. Pec. typ e Sp. typ e T range magnetic? The p osition of di erent kinds of CP stars of the up- e He-weak B4-B8 13000-17000 Yes/No p er Main Sequence i.e. Am stars and the four cate- Si B7-A0 9000-14000 Yes gories of Ap stars: He-weak, HgMn, Si and SrCrEu HgMn B8-A0 10000-14000 No in the HR diagram is examined. Using only those SrCrEu A0-F0 7000-10000 Yes stars having a parallax with a relative error smaller Am A0-F0 7000-10000 No than 0.14 M 0:3 and an absolutely certain v p eculiarity, it is shown that their absolute magni- tudes are similar to those obtained from CP stars in clusters. CP stars are scattered on the whole width of the Main Sequence band. However, the rapidly or Ap stars and a sp ecial distribution of orbital pa- oscillating Ap stars seem slightly less evolved, hence rameters for those CP stars which are members of less massive as a group, than their non-oscillating binary systems.
    [Show full text]