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The Nearest Stars: a Guided Tour by Sherwood Harrington, Astronomical Society of the Pacific
www.astrosociety.org/uitc No. 5 - Spring 1986 © 1986, Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, CA 94112. The Nearest Stars: A Guided Tour by Sherwood Harrington, Astronomical Society of the Pacific A tour through our stellar neighborhood As evening twilight fades during April and early May, a brilliant, blue-white star can be seen low in the sky toward the southwest. That star is called Sirius, and it is the brightest star in Earth's nighttime sky. Sirius looks so bright in part because it is a relatively powerful light producer; if our Sun were suddenly replaced by Sirius, our daylight on Earth would be more than 20 times as bright as it is now! But the other reason Sirius is so brilliant in our nighttime sky is that it is so close; Sirius is the nearest neighbor star to the Sun that can be seen with the unaided eye from the Northern Hemisphere. "Close'' in the interstellar realm, though, is a very relative term. If you were to model the Sun as a basketball, then our planet Earth would be about the size of an apple seed 30 yards away from it — and even the nearest other star (alpha Centauri, visible from the Southern Hemisphere) would be 6,000 miles away. Distances among the stars are so large that it is helpful to express them using the light-year — the distance light travels in one year — as a measuring unit. In this way of expressing distances, alpha Centauri is about four light-years away, and Sirius is about eight and a half light- years distant. -
XIII Publications, Presentations
XIII Publications, Presentations 1. Refereed Publications E., Kawamura, A., Nguyen Luong, Q., Sanhueza, P., Kurono, Y.: 2015, The 2014 ALMA Long Baseline Campaign: First Results from Aasi, J., et al. including Fujimoto, M.-K., Hayama, K., Kawamura, High Angular Resolution Observations toward the HL Tau Region, S., Mori, T., Nishida, E., Nishizawa, A.: 2015, Characterization of ApJ, 808, L3. the LIGO detectors during their sixth science run, Classical Quantum ALMA Partnership, et al. including Asaki, Y., Hirota, A., Nakanishi, Gravity, 32, 115012. K., Espada, D., Kameno, S., Sawada, T., Takahashi, S., Ao, Y., Abbott, B. P., et al. including Flaminio, R., LIGO Scientific Hatsukade, B., Matsuda, Y., Iono, D., Kurono, Y.: 2015, The 2014 Collaboration, Virgo Collaboration: 2016, Astrophysical Implications ALMA Long Baseline Campaign: Observations of the Strongly of the Binary Black Hole Merger GW150914, ApJ, 818, L22. Lensed Submillimeter Galaxy HATLAS J090311.6+003906 at z = Abbott, B. P., et al. including Flaminio, R., LIGO Scientific 3.042, ApJ, 808, L4. Collaboration, Virgo Collaboration: 2016, Observation of ALMA Partnership, et al. including Asaki, Y., Hirota, A., Nakanishi, Gravitational Waves from a Binary Black Hole Merger, Phys. Rev. K., Espada, D., Kameno, S., Sawada, T., Takahashi, S., Kurono, Lett., 116, 061102. Y., Tatematsu, K.: 2015, The 2014 ALMA Long Baseline Campaign: Abbott, B. P., et al. including Flaminio, R., LIGO Scientific Observations of Asteroid 3 Juno at 60 Kilometer Resolution, ApJ, Collaboration, Virgo Collaboration: 2016, GW150914: Implications 808, L2. for the Stochastic Gravitational-Wave Background from Binary Black Alonso-Herrero, A., et al. including Imanishi, M.: 2016, A mid-infrared Holes, Phys. -
Chapter 16 the Sun and Stars
Chapter 16 The Sun and Stars Stargazing is an awe-inspiring way to enjoy the night sky, but humans can learn only so much about stars from our position on Earth. The Hubble Space Telescope is a school-bus-size telescope that orbits Earth every 97 minutes at an altitude of 353 miles and a speed of about 17,500 miles per hour. The Hubble Space Telescope (HST) transmits images and data from space to computers on Earth. In fact, HST sends enough data back to Earth each week to fill 3,600 feet of books on a shelf. Scientists store the data on special disks. In January 2006, HST captured images of the Orion Nebula, a huge area where stars are being formed. HST’s detailed images revealed over 3,000 stars that were never seen before. Information from the Hubble will help scientists understand more about how stars form. In this chapter, you will learn all about the star of our solar system, the sun, and about the characteristics of other stars. 1. Why do stars shine? 2. What kinds of stars are there? 3. How are stars formed, and do any other stars have planets? 16.1 The Sun and the Stars What are stars? Where did they come from? How long do they last? During most of the star - an enormous hot ball of gas day, we see only one star, the sun, which is 150 million kilometers away. On a clear held together by gravity which night, about 6,000 stars can be seen without a telescope. -
The Sky Tonight
MARCH POUTŪ-TE-RANGI HIGHLIGHTS Conjunction of Saturn and the Moon A conjunction is when two astronomical objects appear close in the sky as seen THE- SKY TONIGHT- - from Earth. The planets, along with the TE AHUA O TE RAKI I TENEI PO Sun and the Moon, appear to travel across Brightest Stars our sky roughly following a path called the At this time of the year, we can see the ecliptic. Each body travels at its own speed, three brightest stars in the night sky. sometimes entering ‘retrograde’ where they The brightness of a star, as seen from seem to move backwards for a period of time Earth, is measured as its apparent (though the backwards motion is only from magnitude. Pictured on the cover is our vantage point, and in fact the planets Sirius, the brightest star in our night sky, are still orbiting the Sun normally). which is 8.6 light-years away. Sometimes these celestial bodies will cross With an apparent magnitude of −1.46, paths along the ecliptic line and occupy the this star can be found in the constellation same space in our sky, though they are still Canis Major, high in the northern sky. millions of kilometres away from each other. Sirius is actually a binary star system, consisting of Sirius A which is twice the On March 19, the Moon and Saturn will be size of the Sun, and a faint white dwarf in conjunction. While the unaided eye will companion named Sirius B. only see Saturn as a bright star-like object (Saturn is the eighth brightest object in our Sirius is almost twice as bright as the night sky), a telescope can offer a spectacular second brightest star in the night sky, view of the ringed planet close to our Moon. -
Ghost Imaging of Space Objects
Ghost Imaging of Space Objects Dmitry V. Strekalov, Baris I. Erkmen, Igor Kulikov, and Nan Yu Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-8099 USA NIAC Final Report September 2014 Contents I. The proposed research 1 A. Origins and motivation of this research 1 B. Proposed approach in a nutshell 3 C. Proposed approach in the context of modern astronomy 7 D. Perceived benefits and perspectives 12 II. Phase I goals and accomplishments 18 A. Introducing the theoretical model 19 B. A Gaussian absorber 28 C. Unbalanced arms configuration 32 D. Phase I summary 34 III. Phase II goals and accomplishments 37 A. Advanced theoretical analysis 38 B. On observability of a shadow gradient 47 C. Signal-to-noise ratio 49 D. From detection to imaging 59 E. Experimental demonstration 72 F. On observation of phase objects 86 IV. Dissemination and outreach 90 V. Conclusion 92 References 95 1 I. THE PROPOSED RESEARCH The NIAC Ghost Imaging of Space Objects research program has been carried out at the Jet Propulsion Laboratory, Caltech. The program consisted of Phase I (October 2011 to September 2012) and Phase II (October 2012 to September 2014). The research team consisted of Drs. Dmitry Strekalov (PI), Baris Erkmen, Igor Kulikov and Nan Yu. The team members acknowledge stimulating discussions with Drs. Leonidas Moustakas, Andrew Shapiro-Scharlotta, Victor Vilnrotter, Michael Werner and Paul Goldsmith of JPL; Maria Chekhova and Timur Iskhakov of Max Plank Institute for Physics of Light, Erlangen; Paul Nu˜nez of Coll`ege de France & Observatoire de la Cˆote d’Azur; and technical support from Victor White and Pierre Echternach of JPL. -
EXTENSIONS of REMARKS April 11, 1973
11958 EXTENSIONS OF REMARKS April 11, 1973 Yea-and-nay votes may occur on that ADJOURNMENT UNTIL 9:30 A.M. IN THE ARMY bill. It is possible, if consent is given, Mr. ROBERT C. BYRD. Mr. P resident, T he following-named officers to be placed that the measure would be temporarily on the retired list in grade indicated under if there be no further business to come the provisions of title 10, United States Code, laid aside from time to time and other before the Senate, I move, in accordance items on the Calendar could be taken section 3962: with the previous order, that the Senate To be lieutenant general up tomorrow and Friday—but only if stand in adjournment until 9:30 a.m. L t. Gen. Julian Johnson Ewell, xxx-xx-xxxx , unanimous consent is gotten. tomorrow. With respect to the bill to amend the A rm y of the U nited S tates (m ajor general, N ational Foundation on the A rts and T he m otion was agreed to; and at U.S. Army) . 5:53 p.m. the Senate adjourned until to- L t. Gen. William R aymond P eers, xxx-xx-x... Humanities A ct, I do not believe that xxx-x... A rmy of the United States (major gen- that bill will be taken up tomorrow. The morrow, Thursday, April 12, 1973, at 9:30 a.m. eral, U.S. Army) . distinguished author of the bill (M r. L t. G en. W illard P earson, xxx-xx-xxxx , PELL) has requested that the bill be taken A rm y of the U nited S tates (m ajor general, U.S. -
ANNUAL REPORT June 30, 2021
JOB TITLE SA FUNDS AR REVISION 8 SERIAL <12345678> TIME Friday, August 27, 2021 JOB NUMBER 393837-1 TYPE PAGE NO. I ANNUAL REPORT June 30, 2021 PORTFOLIOS OF INVESTMENTS SA U.S. Fixed Income Fund SA Global Fixed Income Fund SA U.S. Core Market Fund SA U.S. Value Fund SA U.S. Small Company Fund SA International Value Fund SA International Small Company Fund SA Emerging Markets Value Fund SA Real Estate Securities Fund SA Worldwide Moderate Growth Fund Beginning on January 1, 2022, as permitted by regulations adopted by the Securities and Exchange Commission, we intend to no longer mail paper copies of each Fund’s shareholder reports, unless you specifically request paper copies of the reports from the SA Funds - Investment Trust (the “Trust”) or from your financial intermediary, such as a broker-dealer or bank. Instead, the reports will be made available on the Trust’s website (http://www.sa-funds.com), and you will be notified by mail each time a report is posted and provided with a website link to access the report. If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to continue to receive paper copies of all future reports free of charge. If you invest through a financial intermediary, you may contact your financial intermediary to request that you continue to receive paper copies of your shareholder reports. If you invest directly with the Trust, you may inform the Trust that you wish to continue receiving paper copies of your shareholder reports by contacting us at (844) 366-0905. -
Tau Ceti Radius: 700,000 Km (109X Earth’S Radius)
Tau Ceti Radius: 700,000 km (109x Earth’s radius) Average surface temperature: 9,000,000° F Basic characteristics: A star somewhat similar to the Sun, Tau Ceti is about the same size and brightness as the Sun. Main elements: Hydrogen & Helium Boll Radius: 2,400 km (0.38x Earth’s radius) Distance from Tau Ceti (main star): 58,000,000 km (about 0.39x that of Earth) Average surface temperature: 527.1° F Basic characteristics: Rocky with an iron core. No atmosphere, Heavy cratering on the surface. Has no moons. Boll dominates its orbit. Main elements: Iron, Magnesium, Nickel, Oxygen, Silicon Bender Radius: 6,000 km (0.95x Earth’s radius) Distance from Tau Ceti (main star): 108,000,000 km (about 0.73x that of Earth) Average surface temperature: 862.3° F Basic characteristics: Rocky with an iron core. Has an extremely thick atmosphere made mostly of carbon dioxide and methane. This heavy atmosphere traps heat and makes it much hotter than it would be otherwise, There is cratering on the surface. Has no moons. Bender dominates its orbit. Main elements: Iron, Silicon, Magnesium, Oxygen, Silicon, Carbon Belior Radius: 1,700 km (0.27x Earth’s radius) Distance from Tau Ceti (main star): 108,000,000 km (about 0.73x that of Earth) Average surface temperature: 862.3° F Basic characteristics: Belior orbits the planet Bender. It is rocky with an iron core. Has no atmosphere. There is heavy cratering on the surface. Main elements: Iron, Silicon, Magnesium, Oxygen, Silicon, Carbon Pern Radius: 6,300 km (0.98x Earth’s radius) Distance from Tau Ceti (main star): 154,000,000 km (about 1.1x that of Earth) Average surface temperature: 58.2° F Basic characteristics: Rocky with an iron core. -
Part 2 – Brightness of the Stars
5th Grade Curriculum Space Systems: Stars and the Solar System An electronic copy of this lesson in color that can be edited is available at the website below, if you click on Soonertarium Curriculum Materials and login in as a guest. The password is “soonertarium”. http://moodle.norman.k12.ok.us/course/index.php?categoryid=16 PART 2 – BRIGHTNESS OF THE STARS -PRELIMINARY MATH BACKGROUND: Students may need to review place values since this lesson uses numbers in the hundred thousands. There are two website links to online education games to review place values in the section. -ACTIVITY - HOW MUCH BIGGER IS ONE NUMBER THAN ANOTHER NUMBER? This activity involves having students listen to the sound that different powers of 10 of BBs makes in a pan, and dividing large groups into smaller groups so that students get a sense for what it means to say that 1,000 is 10 times bigger than 100. Astronomy deals with many big numbers, and so it is important for students to have a sense of what these numbers mean so that they can compare large distances and big luminosities. -ACTIVITY – WHICH STARS ARE THE BRIGHTEST IN THE SKY? This activity involves introducing the concepts of luminosity and apparent magnitude of stars. The constellation Canis Major was chosen as an example because Sirius has a much smaller luminosity but a much bigger apparent magnitude than the other stars in the constellation, which leads to the question what else effects the brightness of a star in the sky. -ACTIVITY – HOW DOES LOCATION AFFECT THE BRIGHTNESS OF STARS? This activity involves having the students test how distance effects apparent magnitude by having them shine flashlights at styrene balls at different distances. -
The HARPS Search for Earth-Like Planets in the Habitable Zone I
A&A 534, A58 (2011) Astronomy DOI: 10.1051/0004-6361/201117055 & c ESO 2011 Astrophysics The HARPS search for Earth-like planets in the habitable zone I. Very low-mass planets around HD 20794, HD 85512, and HD 192310, F. Pepe1,C.Lovis1, D. Ségransan1,W.Benz2, F. Bouchy3,4, X. Dumusque1, M. Mayor1,D.Queloz1, N. C. Santos5,6,andS.Udry1 1 Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Versoix, Switzerland e-mail: [email protected] 2 Physikalisches Institut Universität Bern, Sidlerstrasse 5, 3012 Bern, Switzerland 3 Institut d’Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France 4 Observatoire de Haute-Provence/CNRS, 04870 St. Michel l’Observatoire, France 5 Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal 6 Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Portugal Received 8 April 2011 / Accepted 15 August 2011 ABSTRACT Context. In 2009 we started an intense radial-velocity monitoring of a few nearby, slowly-rotating and quiet solar-type stars within the dedicated HARPS-Upgrade GTO program. Aims. The goal of this campaign is to gather very-precise radial-velocity data with high cadence and continuity to detect tiny signatures of very-low-mass stars that are potentially present in the habitable zone of their parent stars. Methods. Ten stars were selected among the most stable stars of the original HARPS high-precision program that are uniformly spread in hour angle, such that three to four of them are observable at any time of the year. -
The Relative Sizes of the Sun and Stars 25
The relative sizes of the sun and stars 25 Stars come in many sizes, but their true appearances are impossible to see without special telescopes. The image to the left was taken by the Hubble Space telescope and resolves the red supergiant star Betelgeuse so that its surface can be just barely seen. Follow the number clues below to compare the sizes of some other familiar stars! Problem 1 - The sun's diameter if 10 times the diameter of Jupiter. If Jupiter is 11 times larger than Earth, how much larger than Earth is the Sun? Problem 2 - Capella is three times larger than Regulus, and Regulus is twice as large as Sirius. How much larger is Capella than Sirius? Problem 3 - Vega is 3/2 the size of Sirius, and Sirius is 1/12 the size of Polaris. How much larger is Polaris than Vega? Problem 4 - Nunki is 1/10 the size of Rigel, and Rigel is 1/5 the size of Deneb. How large is Nunki compared to Deneb? Problem 5 - Deneb is 1/8 the size of VY Canis Majoris, and VY Canis Majoris is 504 times the size of Regulus. How large is Deneb compared to Regulus? Problem 6 - Aldebaran is 3 times the size of Capella, and Capella is twice the size of Polaris. How large is Aldebaran compared to Polaris? Problem 7 - Antares is half the size of Mu Cephi. If Mu Cephi is 28 times as large as Rigel, and Rigel is 50 times as large as Alpha Centauri, how large is Antares compared to Alpha Centauri? Problem 8 - The Sun is 1/4 the diameter of Regulus. -
Starshade Rendezvous Probe
Starshade Rendezvous Probe Starshade Rendezvous Probe Study Report Imaging and Spectra of Exoplanets Orbiting our Nearest Sunlike Star Neighbors with a Starshade in the 2020s February 2019 TEAM MEMBERS Principal Investigators Sara Seager, Massachusetts Institute of Technology N. Jeremy Kasdin, Princeton University Co-Investigators Jeff Booth, NASA Jet Propulsion Laboratory Matt Greenhouse, NASA Goddard Space Flight Center Doug Lisman, NASA Jet Propulsion Laboratory Bruce Macintosh, Stanford University Stuart Shaklan, NASA Jet Propulsion Laboratory Melissa Vess, NASA Goddard Space Flight Center Steve Warwick, Northrop Grumman Corporation David Webb, NASA Jet Propulsion Laboratory Study Team Andrew Romero-Wolf, NASA Jet Propulsion Laboratory John Ziemer, NASA Jet Propulsion Laboratory Andrew Gray, NASA Jet Propulsion Laboratory Michael Hughes, NASA Jet Propulsion Laboratory Greg Agnes, NASA Jet Propulsion Laboratory Jon Arenberg, Northrop Grumman Corporation Samuel (Case) Bradford, NASA Jet Propulsion Laboratory Michael Fong, NASA Jet Propulsion Laboratory Jennifer Gregory, NASA Jet Propulsion Laboratory Steve Matousek, NASA Jet Propulsion Laboratory Jonathan Murphy, NASA Jet Propulsion Laboratory Jason Rhodes, NASA Jet Propulsion Laboratory Dan Scharf, NASA Jet Propulsion Laboratory Phil Willems, NASA Jet Propulsion Laboratory Science Team Simone D'Amico, Stanford University John Debes, Space Telescope Science Institute Shawn Domagal-Goldman, NASA Goddard Space Flight Center Sergi Hildebrandt, NASA Jet Propulsion Laboratory Renyu Hu, NASA