Observing Exoplanets
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
CENTAURI II Benutzerhandbuch
CENTAURI II Benutzerhandbuch SW-Version ab 3.1.0.73 MAYAH, CENTAURI, FLASHCAST sind eingetragene Warenzeichen. Alle anderen verwendeten Warenzeichen werden hiermit anerkannt. CENTAURI II Benutzerhandbuch ab SW 3.1.0.73 Bestell-Nr. CIIUM001 Stand 11/2005 (c) Copyright by MAYAH Communications GmbH Die Vervielfältigung des vorliegenden Handbuches, sowie der darin besprochenen Dokumentationen aus dem Internet, auch nur auszugsweise, ist nur mit ausdrücklicher schriftlicher Genehmigung der MAYAH Communications GmbH erlaubt. 1 Einführung ........................................................................................................... 1 1.1 Vorwort......................................................................................................... 1 1.2 Einbau / Installation ...................................................................................... 2 1.3 Lieferumfang ................................................................................................ 2 1.4 Umgebungs- / Betriebsbedingung................................................................ 2 1.5 Anschlüsse................................................................................................... 3 2 Verbindungsaufbau ............................................................................................. 4 2.1 ISDN Verbindungen mit dem Centauri II ...................................................... 4 2.1.1 FlashCast Technologie und Audiocodec Kategorien............................. 4 2.1.2 Wie bekomme ich eine synchronisierte Verbindung -
Lurking in the Shadows: Wide-Separation Gas Giants As Tracers of Planet Formation
Lurking in the Shadows: Wide-Separation Gas Giants as Tracers of Planet Formation Thesis by Marta Levesque Bryan In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2018 Defended May 1, 2018 ii © 2018 Marta Levesque Bryan ORCID: [0000-0002-6076-5967] All rights reserved iii ACKNOWLEDGEMENTS First and foremost I would like to thank Heather Knutson, who I had the great privilege of working with as my thesis advisor. Her encouragement, guidance, and perspective helped me navigate many a challenging problem, and my conversations with her were a consistent source of positivity and learning throughout my time at Caltech. I leave graduate school a better scientist and person for having her as a role model. Heather fostered a wonderfully positive and supportive environment for her students, giving us the space to explore and grow - I could not have asked for a better advisor or research experience. I would also like to thank Konstantin Batygin for enthusiastic and illuminating discussions that always left me more excited to explore the result at hand. Thank you as well to Dimitri Mawet for providing both expertise and contagious optimism for some of my latest direct imaging endeavors. Thank you to the rest of my thesis committee, namely Geoff Blake, Evan Kirby, and Chuck Steidel for their support, helpful conversations, and insightful questions. I am grateful to have had the opportunity to collaborate with Brendan Bowler. His talk at Caltech my second year of graduate school introduced me to an unexpected population of massive wide-separation planetary-mass companions, and lead to a long-running collaboration from which several of my thesis projects were born. -
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. -
The Tierras Observatory: an Ultra-Precise Photometer to Characterize Nearby Terrestrial Exoplanets
The Tierras Observatory: An ultra-precise photometer to characterize nearby terrestrial exoplanets Juliana Garc´ıa-Mej´ıaa, David Charbonneaua, Daniel Fabricanta, Jonathan M. Irwina, Robert Fataa, Joseph M. Zajaca, and Peter E. Dohertya aCenter for Astrophysics Harvard and Smithsonian, 60 Garden Street, Cambridge MA j ABSTRACT We report on the status of the Tierras Observatory, a refurbished 1.3-m ultra-precise fully-automated photometer located at the F. L. Whipple Observatory atop Mt. Hopkins, Arizona. Tierras is designed to limit systematic errors, notably precipitable water vapor (PWV), to 250 ppm, enabling the characterization of terrestrial planet transits orbiting < 0:3 R stars, as well as the potential discovery of exo-moons and exo-rings. The design choices that will enable our science goals include: a four-lens focal reducer and field-flattener to increase the field-of-view of the telescope from a 11:940 to a 0:48◦ side; a custom narrow bandpass (40:2 nm FWHM) filter centered around 863:5 nm to minimize PWV errors known to limit ground-based photometry of red dwarfs; and a deep-depletion 4K 4K CCD with a 300ke- full well and QE> 85% in our bandpass, operating in frame transfer mode. We are also× pursuing the design of a set of baffles to minimize the significant amount of scattered light reaching the image plane. Tierras will begin science operations in early 2021. Keywords: ultra-precise photometry, terrestrial planet detection, exoplanet instrumentation, transit method 1. INTRODUCTION The construction of observatories tailor-built to routinely achieve precise photometry from the ground is mo- tivated by the multitude of exoplanetary and stellar phenomena whose exploration will be enabled with high- cadence, ultra-precise time series of diverse stellar targets. -
Arxiv:1809.07342V1 [Astro-Ph.SR] 19 Sep 2018
Draft version September 21, 2018 Preprint typeset using LATEX style emulateapj v. 11/10/09 FAR-ULTRAVIOLET ACTIVITY LEVELS OF F, G, K, AND M DWARF EXOPLANET HOST STARS* Kevin France1, Nicole Arulanantham1, Luca Fossati2, Antonino F. Lanza3, R. O. Parke Loyd4, Seth Redfield5, P. Christian Schneider6 Draft version September 21, 2018 ABSTRACT We present a survey of far-ultraviolet (FUV; 1150 { 1450 A)˚ emission line spectra from 71 planet- hosting and 33 non-planet-hosting F, G, K, and M dwarfs with the goals of characterizing their range of FUV activity levels, calibrating the FUV activity level to the 90 { 360 A˚ extreme-ultraviolet (EUV) stellar flux, and investigating the potential for FUV emission lines to probe star-planet interactions (SPIs). We build this emission line sample from a combination of new and archival observations with the Hubble Space Telescope-COS and -STIS instruments, targeting the chromospheric and transition region emission lines of Si III,N V,C II, and Si IV. We find that the exoplanet host stars, on average, display factors of 5 { 10 lower UV activity levels compared with the non-planet hosting sample; this is explained by a combination of observational and astrophysical biases in the selection of stars for radial-velocity planet searches. We demonstrate that UV activity-rotation relation in the full F { M star sample is characterized by a power-law decline (with index α ≈ −1.1), starting at rotation periods & 3.5 days. Using N V or Si IV spectra and a knowledge of the star's bolometric flux, we present a new analytic relationship to estimate the intrinsic stellar EUV irradiance in the 90 { 360 A˚ band with an accuracy of roughly a factor of ≈ 2. -
Materials Challenges for the Starshot Lightsail
PERSPECTIVE https://doi.org/10.1038/s41563-018-0075-8 Materials challenges for the Starshot lightsail Harry A. Atwater 1*, Artur R. Davoyan1, Ognjen Ilic1, Deep Jariwala1, Michelle C. Sherrott 1, Cora M. Went2, William S. Whitney2 and Joeson Wong 1 The Starshot Breakthrough Initiative established in 2016 sets an audacious goal of sending a spacecraft beyond our Solar System to a neighbouring star within the next half-century. Its vision for an ultralight spacecraft that can be accelerated by laser radiation pressure from an Earth-based source to ~20% of the speed of light demands the use of materials with extreme properties. Here we examine stringent criteria for the lightsail design and discuss fundamental materials challenges. We pre- dict that major research advances in photonic design and materials science will enable us to define the pathways needed to realize laser-driven lightsails. he Starshot Breakthrough Initiative has challenged a broad nanocraft, we reveal a balance between the high reflectivity of the and interdisciplinary community of scientists and engineers sail, required for efficient photon momentum transfer; large band- Tto design an ultralight spacecraft or ‘nanocraft’ that can reach width, accounting for the Doppler shift; and the low mass necessary Proxima Centauri b — an exoplanet within the habitable zone of for the spacecraft to accelerate to near-relativistic speeds. We show Proxima Centauri and 4.2 light years away from Earth — in approxi- that nanophotonic structures may be well-suited to meeting such mately -
Polarimetry in Bistatic Configuration for Ultra High Frequency Radar Measurements on Forest Environment Etienne Everaere
Polarimetry in Bistatic Configuration for Ultra High Frequency Radar Measurements on Forest Environment Etienne Everaere To cite this version: Etienne Everaere. Polarimetry in Bistatic Configuration for Ultra High Frequency Radar Measure- ments on Forest Environment. Optics [physics.optics]. Ecole Polytechnique, 2015. English. tel- 01199522 HAL Id: tel-01199522 https://hal.archives-ouvertes.fr/tel-01199522 Submitted on 15 Sep 2015 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. École Doctorale de l’École Polytechnie Thèse présentée pour obtenir le grade de docteur de l’École Polytechnique spécialité physique par Étienne Everaere Polarimetry in Bistatic Conguration for Ultra High Frequency Radar Measurements on Forest Environment Directeur de thèse : Antonello De Martino Soutenue le 6 mai 2015 devant le jury composé de : Rapporteurs : François Goudail - Professeur à l’Institut d’optique Graduate School Fabio Rocca - Professeur à L’École Polytechnique de Milan Examinateurs : Élise Colin-K÷niguer - Ingénieur de recherche à l’ONERA Carole Nahum - Responsable -
Prospects of Detecting the Polarimetric Signature of the Earth-Mass Planet Α Centauri B B with SPHERE/ZIMPOL
A&A 556, A64 (2013) Astronomy DOI: 10.1051/0004-6361/201321881 & c ESO 2013 Astrophysics Prospects of detecting the polarimetric signature of the Earth-mass planet α Centauri B b with SPHERE/ZIMPOL J. Milli1,2, D. Mouillet1,D.Mawet2,H.M.Schmid3, A. Bazzon3, J. H. Girard2,K.Dohlen4, and R. Roelfsema3 1 Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), University Joseph Fourier, CNRS, BP 53, 38041 Grenoble, France e-mail: [email protected] 2 European Southern Observatory, Casilla 19001, Santiago 19, Chile 3 Institute for Astronomy, ETH Zurich, 8093 Zurich, Switzerland 4 Laboratoire d’Astrophysique de Marseille (LAM),13388 Marseille, France Received 12 May 2013 / Accepted 4 June 2013 ABSTRACT Context. Over the past five years, radial-velocity and transit techniques have revealed a new population of Earth-like planets with masses of a few Earth masses. Their very close orbit around their host star requires an exquisite inner working angle to be detected in direct imaging and sets a challenge for direct imagers that work in the visible range, such as SPHERE/ZIMPOL. Aims. Among all known exoplanets with less than 25 Earth masses we first predict the best candidate for direct imaging. Our primary objective is then to provide the best instrument setup and observing strategy for detecting such a peculiar object with ZIMPOL. As a second step, we aim at predicting its detectivity. Methods. Using exoplanet properties constrained by radial velocity measurements, polarimetric models and the diffraction propaga- tion code CAOS, we estimate the detection sensitivity of ZIMPOL for such a planet in different observing modes of the instrument. -
100 Closest Stars Designation R.A
100 closest stars Designation R.A. Dec. Mag. Common Name 1 Gliese+Jahreis 551 14h30m –62°40’ 11.09 Proxima Centauri Gliese+Jahreis 559 14h40m –60°50’ 0.01, 1.34 Alpha Centauri A,B 2 Gliese+Jahreis 699 17h58m 4°42’ 9.53 Barnard’s Star 3 Gliese+Jahreis 406 10h56m 7°01’ 13.44 Wolf 359 4 Gliese+Jahreis 411 11h03m 35°58’ 7.47 Lalande 21185 5 Gliese+Jahreis 244 6h45m –16°49’ -1.43, 8.44 Sirius A,B 6 Gliese+Jahreis 65 1h39m –17°57’ 12.54, 12.99 BL Ceti, UV Ceti 7 Gliese+Jahreis 729 18h50m –23°50’ 10.43 Ross 154 8 Gliese+Jahreis 905 23h45m 44°11’ 12.29 Ross 248 9 Gliese+Jahreis 144 3h33m –9°28’ 3.73 Epsilon Eridani 10 Gliese+Jahreis 887 23h06m –35°51’ 7.34 Lacaille 9352 11 Gliese+Jahreis 447 11h48m 0°48’ 11.13 Ross 128 12 Gliese+Jahreis 866 22h39m –15°18’ 13.33, 13.27, 14.03 EZ Aquarii A,B,C 13 Gliese+Jahreis 280 7h39m 5°14’ 10.7 Procyon A,B 14 Gliese+Jahreis 820 21h07m 38°45’ 5.21, 6.03 61 Cygni A,B 15 Gliese+Jahreis 725 18h43m 59°38’ 8.90, 9.69 16 Gliese+Jahreis 15 0h18m 44°01’ 8.08, 11.06 GX Andromedae, GQ Andromedae 17 Gliese+Jahreis 845 22h03m –56°47’ 4.69 Epsilon Indi A,B,C 18 Gliese+Jahreis 1111 8h30m 26°47’ 14.78 DX Cancri 19 Gliese+Jahreis 71 1h44m –15°56’ 3.49 Tau Ceti 20 Gliese+Jahreis 1061 3h36m –44°31’ 13.09 21 Gliese+Jahreis 54.1 1h13m –17°00’ 12.02 YZ Ceti 22 Gliese+Jahreis 273 7h27m 5°14’ 9.86 Luyten’s Star 23 SO 0253+1652 2h53m 16°53’ 15.14 24 SCR 1845-6357 18h45m –63°58’ 17.40J 25 Gliese+Jahreis 191 5h12m –45°01’ 8.84 Kapteyn’s Star 26 Gliese+Jahreis 825 21h17m –38°52’ 6.67 AX Microscopii 27 Gliese+Jahreis 860 22h28m 57°42’ 9.79, -
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. -
Desert Skies Since 1954 Spring 2015 Volume LXI, Issue 1
Tucson Amateur Astronomy Association Observing our Desert Skies since 1954 Spring 2015 Volume LXI, Issue 1 Inside this issue: The Tadpoles in IC410 President’s 2 Letter Outreach 3, 5 New RideShare 7 Program Observing & 8 - 11 Imaging Featured 12, 14 Articles Classifieds 7 Sponsors 7 Contacts 15 Take Note! Science Fair and Book Festival Reports TAAA member Howard Bower photographed IC 410 which is found in Auriga TAAA RideShare Program using a Telescope Engineering Company TEC 140 ED apochromat refractor with Announced a field flattener resulting in f/7.4. This is a narrow band image with 34 exposures in Hydrogen Alpha (30 minutes each), 34 exposures in Oxygen III (binned 2x2 at Jupiter Opposition 2015 15 minutes each), and 34 exposures in Sulphur II (binned 2x2 at 15 minutes each). Report IC410 is a faint emission nebula surrounding the star cluster NGC 1893. At the Constellation of the top left of the nebula are two objects known as “The Tadpoles”. These are likely Season—Centaurus areas of stellar formation. Each tadpole is about 10 light years long. This object is at a distance of about 12,000 light years. © 2013 Howard Bower. Used by New Items in the Classifieds permission. Desert Skies Page 2 Volume LXI, Issue 1 From Our President As I reviewed the March Bulletin it was really heartwarming to see all of the activities in which we are involved. It takes a lot of Our mission is to provide opportunities for members dedication and hard work to put this all together and make it and the public to share the joy and excitement of work.. -
Biosignatures Search in Habitable Planets
galaxies Review Biosignatures Search in Habitable Planets Riccardo Claudi 1,* and Eleonora Alei 1,2 1 INAF-Astronomical Observatory of Padova, Vicolo Osservatorio, 5, 35122 Padova, Italy 2 Physics and Astronomy Department, Padova University, 35131 Padova, Italy * Correspondence: [email protected] Received: 2 August 2019; Accepted: 25 September 2019; Published: 29 September 2019 Abstract: The search for life has had a new enthusiastic restart in the last two decades thanks to the large number of new worlds discovered. The about 4100 exoplanets found so far, show a large diversity of planets, from hot giants to rocky planets orbiting small and cold stars. Most of them are very different from those of the Solar System and one of the striking case is that of the super-Earths, rocky planets with masses ranging between 1 and 10 M⊕ with dimensions up to twice those of Earth. In the right environment, these planets could be the cradle of alien life that could modify the chemical composition of their atmospheres. So, the search for life signatures requires as the first step the knowledge of planet atmospheres, the main objective of future exoplanetary space explorations. Indeed, the quest for the determination of the chemical composition of those planetary atmospheres rises also more general interest than that given by the mere directory of the atmospheric compounds. It opens out to the more general speculation on what such detection might tell us about the presence of life on those planets. As, for now, we have only one example of life in the universe, we are bound to study terrestrial organisms to assess possibilities of life on other planets and guide our search for possible extinct or extant life on other planetary bodies.