DOCSLIB.ORG

Metode Detekcija Vansolarnih Planeta

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Metode Detekcija Vansolarnih Planeta UNIVERZITET U NIŠU PRIRODNO-MATEMATIČKI FAKULET DEPARTMAN ZA FIZIKU Metode detekcija vansolarnih planeta MASTER RAD Kandidat: Mentor: Kristina Stanković Prof. dr Dragan Gajić Broj indeksa: 18 Niš, septembar 2019. Zahvaljujem se svom mentoru prof. dr Draganu Gajiću na predloženoj temim, nesebičnoj stručnoj pomoći i korisnim savetima prilikom izrade ovog master rada. Zahvaljujem se Jaroslavu Grnji i Janku Mraviku iz Astronomskog društva „Univerzum“ za ustupanje svog posmatračkog materijala. Veliku zahvalnost dugujem svom suprugu Čedomiru, kao i ostaloj porodici na strpljenju, podršci i razumevanju. Kristina Stanković, septembar 2019. Прилог 5/1 ПРИРОДНO - MАТЕМАТИЧКИ ФАКУЛТЕТ НИШ КЉУЧНА ДОКУМЕНТАЦИЈСКА ИНФОРМАЦИЈА Редни број, РБР: Идентификациони број, ИБР: Тип документације, ТД: монографска Тип записа, ТЗ: текстуални / графички Врста рада, ВР: мастер рад Аутор, АУ: Кристина Станковић Ментор, МН: Драган Гајић Наслов рада, НР: МЕТОДЕ ДЕТЕКЦИЈА ВАНСОЛАРНИХ ПЛАНЕТА Језик публикације, ЈП: српски Језик извода, ЈИ: енглески Земља публиковања, ЗП: Р. Србија Уже географско подручје, УГП: Р. Србија Година, ГО: 2019. Издавач, ИЗ: ауторски репринт Место и адреса, МА: Ниш, Вишеградска 33. Физички опис рада, ФО: 9 поглавља, 2 прилога, 66 страна, 27 слика и графичких (поглавља/страна/ цитата/табела/слика/графика/прилога) приказа Научна област, НО: физика Научна дисциплина, НД: астрофизика Предметна одредница/Кључне речи, ПО: вансоларне планете, методе детекција УДК 52.126:524 Чува се, ЧУ: библиотека Важна напомена, ВН: Посматрачки материјал је снимљен на опсерваторији Астрономског друштва «Универзум» у Бачкој Паланци Извод, ИЗ: Последњих година расте интересовање за истраживањем постојећих и откривањем нових вансоларних планета. У овом раду дат је преглед шест метода детекција вансоларних планета које се тренутно користе: астрометријска метода, метода радијалних брзина, метода гравитационих микросочива, мерење периода пулсара, директно снимање и метода транзита. Анализирани су посматрачки подаци добијени применом фотометријске методе транзита познатих вансоларне планете TrES-1b и TrES-3b и представљене су њихове криве сјаја. Датум прихватања теме, ДП: 28.09.2017. Датум одбране, ДО: Чланови комисије, КО: Председник: Члан: Mентор: проф. др Драган Гајић Образац Q4.09.13 - Издање 1 Прилог 5/2 ПРИРОДНО - МАТЕМАТИЧКИ ФАКУЛТЕТ НИШ KEY WORDS DOCUMENTATION Accession number, ANO: Identification number, INO: Document type, DT: monograph Type of record, TR: textual / graphic Contents code, CC: master thesis Author, AU: Kristina Stanković Mentor, MN: Dragan Gajić Title, TI: THE METHODS FOR DETECTING EXTRASOLAR PLANETS Language of text, LT: Serbian Language of abstract, LA: English Country of publication, CP: Republic of Serbia Locality of publication, LP: Serbia Publication year, PY: 2019 Publisher, PB: author’s reprint Publication place, PP: Niš, Višegradska 33. Physical description, PD: 9 chapters / 66 pages / 2 appendixes / 27 pictures and graphic (chapters/pages/ref./tables/pictures/graphs/appendixes) representations Scientific field, SF: physics Scientific discipline, SD: astrophysics Subject/Key words, S/KW: extrasolar planets ; methods for detecting UC 52.126:524 Holding data, HD: library Note, N: Observations were made at the observatory of the Astronomical Society “Universe” from Backa Palanka, Serbia. Abstract, AB: In recent years, there has been a growing interest in exploring existing and discovering new extrasolar planets, both professional and amateur astronomers. This paper reviews six extrasolar planet detection methods currently in use: astrometric method, radial velocity method, gravitational microwave method, pulsar period measurement, direct imaging and transit method. The observed data obtained by the photometric transit method of the known extrasolar planets TrES-1b and TrES-3b were analyzed and their light curves are presented. Accepted by the Scientific Board on, ASB: 28.09.2017. Defended on, DE: Defended Board, DB: President: Member: Mentor: prof. dr Dragan Gajić Образац Q4.09.13 - Издање 1 SADRŽAJ 1. UVOD ............................................................................................................................ 3 2. MLEČNI PUT, ZVEZDE, PLANETE ....................................................................... 6 2.1.Mlečni put .................................................................................................................. 6 2.2.Nastanak zvezda ........................................................................................................ 6 2.3.Formiranje planeta i Sunčev sistem ........................................................................... 9 2.4.Definicija planeta .................................................................................................... 10 2.5.Nastanjive zone ....................................................................................................... 11 3. VANSOLARNE PLANETE I SISTEMI ................................................................. 14 4. METODE DETEKCIJE VANSOLARNIH PLANETA ........................................ 18 4.1.Astrometrijska metoda ............................................................................................ 19 4.2.Metoda radijalnih brzina ......................................................................................... 20 4.3.Metoda gravitacionih mikrosočiva .......................................................................... 22 4.4.Merenje perioda pulsara .......................................................................................... 26 4.5.Direktno snimanje ................................................................................................... 27 5. METODA TRANZITA ............................................................................................. 30 5.1.Kriva sjaja tranzita vansolarnih planeta .................................................................. 30 5.1.1. Opservable ...................................................................................................... 31 6. FOTOMETRIJSKA METODA TRANZITA ......................................................... 36 6.1.Diferencijalna fotometrija ....................................................................................... 36 6.2.CCD fotometrija ...................................................................................................... 37 6.2.1. Kvantna efikasnost ......................................................................................... 38 6.2.2. Broj fotona ...................................................................................................... 38 6.2.3. Fotometrijsko snimanje .................................................................................. 38 6.3.Greška merenja i njeno otklanjanje ......................................................................... 39 6.4.Kvantni šum ............................................................................................................ 40 6.5.Julijanski dan i modifikovani julijanski dan ............................................................ 41 6.6.Heliocentrični julijanski dan ................................................................................... 42 7. SNIMANJE TRANZITA VANSOLARNIH PLANETA TrES-1b I TrES-3b ..... 43 7.1.TrES-1b ................................................................................................................... 43 7.2.TrES-3b ................................................................................................................... 44 1 7.3.Metoda posmatranja ................................................................................................ 44 7.3.1. Instrumenti ...................................................................................................... 44 7.4.Redukcija i analiza posmatračkog materijala .......................................................... 45 7.4.1. FotoDif 3.109 ................................................................................................. 46 8. REZULTATI POSMATRANJA .............................................................................. 50 9. ZAKLJUČAK ............................................................................................................ 53 PRILOG I ........................................................................................................................ 55 1. Spektralna klasifikacija zvezda ................................................................................. 55 2. Spektralne klase zvezda ............................................................................................ 55 3. Klase emisivnosti zvezda .......................................................................................... 56 4. Hercšprung-Raselov (H-R) dijagram ........................................................................ 56 PRILOG II ...................................................................................................................... 58 1. Osnovni elementi putanje planeta ............................................................................. 58 2. Prava, ekscentrična i srednja anomalija ................................................................... 59 3. Eliptični elementi kretanja planeta ............................................................................ 60 4. Keplerovi zakoni ....................................................................................................... 61 LITERATURA ..............................................................................................................
Load more

Recommended publications
  • Extrasolar Planets
    Extrasolar Planets to appear in Encyclopedia of Time, Sage Publishing, in preparation, H.J. Birx (Ed.) The term extrasolar planets or exoplanets stands for planets outside our Solar System, i.e. not orbiting the Sun, but other stars. Planets in our Solar System are defined as objects with enough mass to be spherical and round by their own gravity and to be alone on their orbit around the Sun, i.e. to be the dominant object in a particular orbit, and not to be a moon or asteroid (see the entry Planet in this encyclopedia for the official definition, the historical debate, and a discussion of the planets of our Solar System). Most exoplanets are discovered by observing the stellar motion around the common center of mass of the star+planet system, i.e. by observing somehow the motion of the objects in orbit around each other, i.e. by measuring precisely the periodic variation of certain values, e.g. radial velocity or brightness, with time, e.g. the first extrasolar planets were found with the timing technique around a pulsating neutron star. The recent definition of Planets of our Solar System by the International Astronomical Union deals mainly with the question of the minimum mass for an object to qualify as planet and excludes Pluto. This matter was raised by the fact that more and more objects similar to Pluto were discovered by larger and larger telescopes. The questions of maximum mass and formation of planets were left out in this new definition, possibly partly because there is not yet a consensus in the international community.
    [Show full text]
  • The Slow Spin of the Young Sub-Stellar Companion GQ Lupi B and Its Orbital Configuration Henriette Schwarz1?, Christian Ginski1, Remco J
    Astronomy & Astrophysics manuscript no. AA-2016-28908-preprint c ESO 2016 July 4, 2016 The slow spin of the young sub-stellar companion GQ Lupi b and its orbital configuration Henriette Schwarz1?, Christian Ginski1, Remco J. de Kok1; 2, Ignas A. G. Snellen1, Matteo Brogi3; 5, and Jayne L. Birkby4; 6 1 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands 2 SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands 3 Center for Astrophysics and Space Astronomy, University of Colorado at Boulder, CO 80309 Boulder, USA 4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MA 02138 Cambridge, USA 5 NASA Hubble Fellow 6 NASA Sagan Fellow ABSTRACT The spin of a planet or brown dwarf is related to the accretion process, and therefore studying spin can help promote our understand- ing of the formation of such objects. We present the projected rotational velocity of the young sub-stellar companion GQ Lupi b, along with its barycentric radial velocity. The directly imaged exoplanet or brown dwarf companion joins a small but growing en- semble of wide-orbit sub-stellar companions with a spin measurement. The GQ Lupi system was observed at high spectral resolution (R ∼100 000), and in the analysis we made use of both spectral and spatial filtering to separate the signal of the companion from that of the host star. We detect both CO (S/N=11.6) and H2O (S/N=7.7) in the atmosphere of GQ Lupi b by cross-correlating with model +0:9 −1 spectra, and we find it to be a slow rotator with a projected rotational velocity of 5:3−1:0 km s .
    [Show full text]
  • An Upper Limit on the Mass of the Circumplanetary Disk for DH Tau B
    Draft version August 28, 2021 Preprint typeset using LATEX style emulateapj v. 12/16/11 AN UPPER LIMIT ON THE MASS OF THE CIRCUM-PLANETARY DISK FOR DH TAU B* Schuyler G. Wolff1, Franc¸ois Menard´ 2, Claudio Caceres3, Charlene Lefevre` 4, Mickael Bonnefoy2,Hector´ Canovas´ 5,Sebastien´ Maret2, Christophe Pinte2, Matthias R. Schreiber6, and Gerrit van der Plas2 Draft version August 28, 2021 ABSTRACT DH Tau is a young (∼1 Myr) classical T Tauri star. It is one of the few young PMS stars known to be associated with a planetary mass companion, DH Tau b, orbiting at large separation and detected by direct imaging. DH Tau b is thought to be accreting based on copious Hα emission and exhibits variable Paschen Beta emission. NOEMA observations at 230 GHz allow us to place constraints on the disk dust mass for both DH Tau b and the primary in a regime where the disks will appear optically thin. We estimate a disk dust mass for the primary, DH Tau A of 17:2 ± 1:7 M⊕, which gives a disk- to-star mass ratio of 0.014 (assuming the usual Gas-to-Dust mass ratio of 100 in the disk). We find a conservative disk dust mass upper limit of 0.42M⊕ for DH Tau b, assuming that the disk temperature is dominated by irradiation from DH Tau b itself. Given the environment of the circumplanetary disk, variable illumination from the primary or the equilibrium temperature of the surrounding cloud would lead to even lower disk mass estimates. A MCFOST radiative transfer model including heating of the circumplanetary disk by DH Tau b and DH Tau A suggests that a mass averaged disk temperature of 22 K is more realistic, resulting in a dust disk mass upper limit of 0.09M⊕ for DH Tau b.
    [Show full text]
  • Giant Planets
    Lyot Conference 5 June 2007 Properties of Exoplanets: from Giants toward Rocky Planets & Informing Coronagraphy Collaborators: Paul Butler, Debra Fischer, Steve Vogt Chris McCarthy, Jason Wright, John Johnson, Katie Peek Chris Tinney, Hugh Jones, Brad Carter Greg Laughlin, Doug Lin, Shigeru Ida, Jack Lissauer, Eugenio Rivera -Stellar Sample - 1330 Nearby FGKM Stars (~2000 stars total with Mayor et al. ) Star Selection Criteria: HipparcosH-R Cat. Diagram d < 100 pc . 1330 Target Stars •Vmag < 10 mag • No Close Binaries • Age > 2 Gyr Lum 1.3 Msun Target List: 0.3 M Published SUN 1 Michel Mayor & Didier Queloz First ExoPlanet 51 Peg Now Stephane Udry plays leadership role also. Doppler Monitering Begun: 1987 Uniform Doppler Precision: 1-3 m s-1 2000 FGKM M.S. Stars Three Telescopes 8 Years 7 Years 19 Years (3.5 AU) (3 AU) (6 AU) Keck Lick Anglo-Aus. Tel. 2 Precision: 1.5 m s-1 3 Years Planets or Brown Dwarfs in Unclosed, Long-Period Orbits: Targets for Coronagraphs 3 Sep ~ 0.3 “ Sep ~ 0.2 “ 4 Sep ~ 0.2” Examples of Jupiter-mass & Saturn mass Planets Detected by RV 5 Jupiter Mass Extrasolar Planets P = 5.3 yr e = 0.47 Jupiter Mass Extrasolar Planets P = 1.3 yr 6 Sub-Saturn Masses: 30 - 100 MEarth Msini = 32 MEarth Msini = 37 MEarth Msini = 57 MEarth Old Doppler Precision: 3 m/s Sub-Saturn Masses: Detectable for P < 2 Month Multiple - Planet Systems 7 HD 12661: Sun-like Star ) (meters/sec Velocity Time (years) 2 - Planet Model 2.5 M J Weak Interactions 1.9 MJ K0V, 1Gy, 16 pc HD 128311 2:1 Resonance Inner Outer Per (d) 458 918 Msini 2.3 3.1 ecc 0.23 0.22 ω 119 212 Pc / Pb = 2.004 Dynamical Resonance (Laughlin) 8 Msini = 1.4 MJ M Dwarfs have distant giant planets.
    [Show full text]
  • Constraints on the Spin Evolution of Young Planetary-Mass Companions Marta L
    Constraints on the Spin Evolution of Young Planetary-Mass Companions Marta L. Bryan1, Björn Benneke2, Heather A. Knutson2, Konstantin Batygin2, Brendan P. Bowler3 1Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125, USA. 2Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. 3McDonald Observatory and Department of Astronomy, University of Texas at Austin, Austin, TX 78712, USA. Surveys of young star-forming regions have discovered a growing population of planetary- 1 mass (<13 MJup) companions around young stars . There is an ongoing debate as to whether these companions formed like planets (that is, from the circumstellar disk)2, or if they represent the low-mass tail of the star formation process3. In this study we utilize high-resolution spectroscopy to measure rotation rates of three young (2-300 Myr) planetary-mass companions and combine these measurements with published rotation rates for two additional companions4,5 to provide a look at the spin distribution of these objects. We compare this distribution to complementary rotation rate measurements for six brown dwarfs with masses <20 MJup, and show that these distributions are indistinguishable. This suggests that either that these two populations formed via the same mechanism, or that processes regulating rotation rates are independent of formation mechanism. We find that rotation rates for both populations are well below their break-up velocities and do not evolve significantly during the first few hundred million years after the end of accretion. This suggests that rotation rates are set during late stages of accretion, possibly by interactions with a circumplanetary disk.
    [Show full text]
  • EPSC2018-126, 2018 European Planetary Science Congress 2018 Eeuropeapn Planetarsy Science Ccongress C Author(S) 2018
    EPSC Abstracts Vol. 12, EPSC2018-126, 2018 European Planetary Science Congress 2018 EEuropeaPn PlanetarSy Science CCongress c Author(s) 2018 Stellar wind interaction with the expanding atmosphere of Gliese 436b A.G. Berezutskiy (1), I.F. Shaikhislamov (1), M.L. Khodachenko (2,3) and I.B. Miroshnichenko (1,4) (1) Institute of Laser Physics, Siberian Brunch Russian Academy of Science, Novosibirsk, Russia; (2) Space Research Institute, Austrian Academy of Science, Graz, Austria; (3) Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow, Russia (4) Novosibirsk State Technical University, Novosibirsk, Russia ([email protected]) Abstract the escaping planetary upper atmospheric material are also taken into account. We study an exosphere of a Neptune-size exoplanet Gliese 436b, orbiting the red dwarf at an extremely 3. Results close distance (0.028 au), taking into account its interaction with the stellar wind plasma flow. It was At the initial state of the simulations, the atmosphere shown that Gliese 436 b has a bowshock region of Gliese 436b is assumed to consist of the molecular between planetary and stellar wind which localized hydrogen and helium atoms at a ratio NHe / NH2 = 1/5 on the distance of ~33 Rp, where density of planetary with the temperature 750 K. We consider the case of -3 atoms slightly dominates over the protons. a weak stellar wind (SW) with nsw=100 cm , Tsw=1 МК, Vsw=70 km/s, which is much less intense than 1. Introduction the solar wind. Because of this fact, , we did not consider generation of Energetic Neutral Atoms The modelled planet Gliese 436b has a mass (ENAs).
    [Show full text]
  • Estudio Numérico De La Dinámica De Planetas
    UNIVERSIDAD PEDAGOGICA´ NACIONAL FACULTAD DE CIENCIA Y TECNOLOG´IA ESTUDIO NUMERICO´ DE LA DINAMICA´ DE PLANETAS EXTRASOLARES Tesis presentada por Eduardo Antonio Mafla Mejia dirigida por: Camilo Delgado Correal Nestor Mendez Hincapie para obtener el grado de Licenciado en F´ısica 2015 Departamento de F´ısica I Dedico este trabajo a mi mam´a, quien me apoyo en mi deseo de seguir el camino de la educaci´on. Sin su apoyo este deseo no lograr´ıa ser hoy una realidad. RESUMEN ANALÍTICO EN EDUCACIÓN - RAE 1. Información General Tipo de documento Trabajo de Grado Acceso al documento Universidad Pedagógica Nacional. Biblioteca Central ESTUDIO NUMÉRICO DE LA DINÁMICA DE PLANETAS Título del documento EXTRASOLARES Autor(es) Mafla Mejia, Eduardo Antonio Director Méndez Hincapié, Néstor; Delgado Correal, Camilo Publicación Bogotá. Universidad Pedagógica Nacional, 2015. 61 p. Unidad Patrocinante Universidad Pedagógica Nacional DINÁMICA DE EXOPLANETAS, LEY GRAVITACIONAL DE NEWTON, Palabras Claves ESTUDIO NUMÉRICO. 2. Descripción Trabajo de grado que se propone evidenciar si el modelo matemático clásico newtoniano, y en consecuencia las tres leyes de Kepler, se puede generalizar a cualquier sistema planetario, o solo es válido para determinados casos particulares. Para lograr esto de comparar numéricamente los efectos de las diferentes correcciones que puede adoptar la ley de gravitación de Newton para modelar la dinámica de planetas extrasolares aplicándolos en los sistemas extrasolares Gliese 876 d, Gliese 436 b y el sistema Mercurio – Sol. En los exoplanetas examinados se encontró, que en un buen grado de aproximación, la dinámica de los exoplanetas se logran describir con el modelo newtoniano, y en consecuencia, modelar su movimiento usando las leyes de Kepler.
    [Show full text]
  • Gas and Dust from Hot, Rocky Exoplanets Delivery of Organic
    Adaptive optics for high-contrast imaging: The Holographic Modal Wavefront Sensor (HMWFS) Goal: Combining focal-plane Meetings feature presentations by PhD students, postdocs and professors wavefront sensing with apodising phase plate coronography to create who are carrying out research relating to planetary science. temporally stable high-contrast regions in the science PSF, suited to Next meeting: 29 MAY 2015 AT LEIDEN OBSERVATORY, LEIDEN UNIVERSITY direct imaging of exoplanets and Michael Wilby If you would like to join or would like more information, Fig: Focal-plane image of a 6 Zernike mode HMWFS, with a) flat their characterisation with next- Leiden Observatory wavefront and b) 1.5 radians defocus error (Z3). Modal content of the generation instrumentation. [email protected] input wavefront is measured directly by coupled pairs of WFS spots please email [email protected]. Aqueous alteration of polycyclic aromatic hydrocarbons Delivery of organic material and water Present in meteorites and asteroids to planets through asteroid impacts at NAC Is it possible through The goal is to define observables for observations aqueous alteration to alter or breakdown with JWST, METIS & SPICA. polycyclic aromatic hydrocarbons We will study the role of "exo-asteroids" in the delivery of water in asteroids/meteorites? and organics to exoplanets which is interesting because water and organics are relevant for astro-biology. Kateryna Frantseva Claudia-Corina Giese Fig: Scanning electron microscope SRON Groningen/Kapteyn Institute, Leiden
    [Show full text]
  • Astrometric and Photometric Monitoring of GQ Lupi and Its Sub-Stellar Companion
    A&A 484, 281–291 (2008) Astronomy DOI: 10.1051/0004-6361:20078493 & c ESO 2008 Astrophysics Astrometric and photometric monitoring of GQ Lupi and its sub-stellar companion R. Neuhäuser1,M.Mugrauer1,A.Seifahrt1,T.O.B.Schmidt1, and N. Vogt2,3 1 Astrophysikalisches Institut, Universität Jena, Schillergässchen 2-3, 07745 Jena, Germany e-mail: [email protected] 2 Departamento de Física y Astronomía, Universidad de Valparaíso, Avenida Gran Bretaña 1111, Valparaíso, Chile 3 Instituto de Astronomía, Universidad Catolica del Norte, Avda. Angamos 0610, Antofagasta, Chile Received 16 August 2007 / Accepted 4 December 2007 ABSTRACT Context. Neuhäuser et al. (2005, A&A, 435, L13) presented direct imaging evidence for a sub-stellar companion to the young T Tauri star GQ Lupi. Common proper motion was highly significant, but no orbital motion was detected. Faint luminosity, low gravity, and a late-M/early-L spectral type indicated that the companion is either a planet or a brown dwarf. Aims. We have monitored GQ Lupi and its companion in order to detect orbital and parallactic motion and variability in its brightness. We also search for closer and fainter companions. Methods. We have taken six more images with the VLT Adaptive Optics instrument NACO from May 2005 to Feb. 2007, always with the same calibration binary from Hipparcos for both astrometric and photometric calibration. By adding up all the images taken so far, we search for additional companions. Results. The position of GQ Lupi A and its companion compared to a nearby non-moving background object varies as expected for parallactic motion by about one pixel (2 · π with parallax π).
    [Show full text]
  • How to Detect Exoplanets Exoplanets: an Exoplanet Or Extrasolar Planet Is a Planet Outside the Solar System
    Exoplanets Matthew Sparks, Sobya Shaikh, Joseph Bayley, Nafiseh Essmaeilzadeh How to detect exoplanets Exoplanets: An exoplanet or extrasolar planet is a planet outside the Solar System. Transit Method: When a planet crosses in front of its star as viewed by an observer, the event is called a transit. Transits by terrestrial planets produce a small change in a star's brightness of about 1/10,000 (100 parts per million, ppm), lasting for 2 to 16 hours. This change must be absolutely periodic if it is caused by a planet. In addition, all transits produced by the same planet must be of the same change in brightness and last the same amount of time, thus providing a highly repeatable signal and robust detection method. Astrometry: Astrometry is the area of study that focuses on precise measurements of the positions and movements of stars and other celestial bodies, as well as explaining these movements. In this method, the gravitational pull of a planet causes a star to change its orbit over time. Careful analysis of the changes in a star's orbit can provide an indication that there exists a massive exoplanet in orbit around the star. The astrometry technique has benefits over other exoplanet search techniques because it can locate planets that orbit far out from the star Radial Velocity method: The radial velocity method to detect exoplanet is based on the detection of variations in the velocity of the central star, due to the changing direction of the gravitational pull from an (unseen) exoplanet as it orbits the star.
    [Show full text]
  • Orders of Magnitude (Length) - Wikipedia
    03/08/2018 Orders of magnitude (length) - Wikipedia Orders of magnitude (length) The following are examples of orders of magnitude for different lengths. Contents Overview Detailed list Subatomic Atomic to cellular Cellular to human scale Human to astronomical scale Astronomical less than 10 yoctometres 10 yoctometres 100 yoctometres 1 zeptometre 10 zeptometres 100 zeptometres 1 attometre 10 attometres 100 attometres 1 femtometre 10 femtometres 100 femtometres 1 picometre 10 picometres 100 picometres 1 nanometre 10 nanometres 100 nanometres 1 micrometre 10 micrometres 100 micrometres 1 millimetre 1 centimetre 1 decimetre Conversions Wavelengths Human-defined scales and structures Nature Astronomical 1 metre Conversions https://en.wikipedia.org/wiki/Orders_of_magnitude_(length) 1/44 03/08/2018 Orders of magnitude (length) - Wikipedia Human-defined scales and structures Sports Nature Astronomical 1 decametre Conversions Human-defined scales and structures Sports Nature Astronomical 1 hectometre Conversions Human-defined scales and structures Sports Nature Astronomical 1 kilometre Conversions Human-defined scales and structures Geographical Astronomical 10 kilometres Conversions Sports Human-defined scales and structures Geographical Astronomical 100 kilometres Conversions Human-defined scales and structures Geographical Astronomical 1 megametre Conversions Human-defined scales and structures Sports Geographical Astronomical 10 megametres Conversions Human-defined scales and structures Geographical Astronomical 100 megametres 1 gigametre
    [Show full text]
  • Exoplanet Atmosphere Measurements from Direct Imaging
    Exoplanet Atmosphere Measurements from Direct Imaging Beth A. Biller and Mickael¨ Bonnefoy Abstract In the last decade, about a dozen giant exoplanets have been directly im- aged in the IR as companions to young stars. With photometry and spectroscopy of these planets in hand from new extreme coronagraphic instruments such as SPHERE at VLT and GPI at Gemini, we are beginning to characterize and classify the at- mospheres of these objects. Initially, it was assumed that young planets would be similar to field brown dwarfs, more massive objects that nonetheless share sim- ilar effective temperatures and compositions. Surprisingly, young planets appear considerably redder than field brown dwarfs, likely a result of their low surface gravities and indicating much different atmospheric structures. Preliminarily, young free-floating planets appear to be as or more variable than field brown dwarfs, due to rotational modulation of inhomogeneous surface features. Eventually, such inho- mogeneity will allow the top of atmosphere structure of these objects to be mapped via Doppler imaging on extremely large telescopes. Direct imaging spectroscopy of giant exoplanets now is a prelude for the study of habitable zone planets. Even- tual direct imaging spectroscopy of a large sample of habitable zone planets with future telescopes such as LUVOIR will be necessary to identify multiple biosigna- tures and establish habitability for Earth-mass exoplanets in the habitable zones of nearby stars. Introduction Since 1995, more than 3000 exoplanets have been discovered, mostly via indirect means, ushering in a completely new field of astronomy. In the last decade, about a dozen planets have been directly imaged, including archetypical systems such as arXiv:1807.05136v1 [astro-ph.EP] 13 Jul 2018 Beth A.
    [Show full text]