Astronomía: En busca de nuevas Tierras
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Presentación del Dr. Rafael Bachiller en su conferencia del 10 de diciembre de 2009 dentro de las Tertulias del Geoforo
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Astronomía: En busca de nuevas Tierras
- 2. Rafael Bachiller Astrónomo y director del Observatorio Astronómico Nacional Miembro de la Real Academia de Doctores de España Formación y detección de sistemas planetarios
- 3. La observación nos proporciona pistas importantes para investigar la formación del sistema solar
- 4. Pista 1.- Los planetas (Plutón no cuenta) se mueven en órbitas casi circulares. Las órbitas son así Nunca así
- 5. Pista 2.- Las órbitas de los planetas tienen el mismo sentido y están en el mismo plano. Siempre así Nunca así
- 6. Pista 3.- Casi todas las lunas giran en el mismo sentido que los planetas y sus órbitas estan en el mismo plano que las órbitas planetarias. Giran siempe así Nunca así
- 7. Pistas 4 y 5.- Los planetas gaseosos son muy grandes y están lejos del Sol Los planetas rocosos son “pequeños” y están cerca del Sol
- 8. Pista 6.- Los planetas contienen elementos pesados El Big Bang produjo un universo de gas: 80 % Hidrógeno, 20 % Helio. Y nada más (excepto pequeñas cantidades de Litio y Deuterio). Sin embargo El Sol y los grandes planetas gaseosos tienen una composición similar, pero incluyen un ~ 1 % de elementos pesados (C, O, N, Fe, Cu, U, etc) Los planetas rocosos están hechos en gran medida de estos elementos pesados.
- 9. Pista 7.- Casi todos los cráteres de la Luna son muy viejos. La datación de rocas traidas de la Luna (Apolo) muestran que casi todos los cráteres tienen edades > 4 10 9 años. En aquella época los meteoritos eran mucho más abundantes que ahora !
- 10. William Herschel descubrió más de 1000 nebulosas. Su catálogo completado por su hijo John en el Hemisferio Sur desembocaría en el General Catalogue (moderno catálogo básico de nebulosas y galaxias: NGC)
- 12. Pierre-Simon Laplace (1749-1827) “ Lo que conocemos no es mucho. Lo que desconocemos es inmenso” Exposition du système du monde (1796): formación del sistema solar a partir de la contracción de una de las nebulosas como las catalogadas por Herschel
- 14. t = 9.000 M. años (hace 4.700 M años) formación del Sistema Solar
- 16. Algunos discos proto-planetarios vistos de canto (imágenes HST, Padgett et al.). Las estrellas centrales están oscurecidas por el polvo del disco.
- 18. De las nubes interestelares a los sistemas planetarios (I) Las estrellas se forman en grandes nubes gaseosas. Las estrellas producen elementos pesados en sus núcleos. Al gas se le añade una centésima de material sólido (“granos de polvo”)
- 19. De las nubes interestelares a los sistemas planetarios (II) El material “placentario” remanente de la formación estelar es un disco En el disco proto-planetario una fluctuación de densidad puede hacer que los granos de polvo se peguen entre sí y acaban formando rocas “planetesimales” Los planatesimales coagulan para formar proto-planetas. Un proto-planeta crea un anillo vacío en el disco
- 20. De las nubes interestelares a los sistemas planetarios (III) La formación en un disco explica las órbitas casi circulares, que todas tengan el mismo sentido, y que estén en el mismo plano (también las órbitas de las lunas) En la época de formación del Sistema Solar debieron abundar los meteoritos: los cráteres de la Luna son casi todos muy viejos pues se formaron en aquella época (hace unos 4 10 9 años)
- 21. De las nubes interestelares a los sistemas planetarios (IV) Los tipos de planetas dependen de la masa final “coagulada” en un medio que contenía gas y material sólido: los planetas más masivos son capaces de capturar gas “ambiente” para formar su atmósfera. Diferentes regiones del disco proto-planetario pueden dar lugar a planetas muy diferentes (reflejando las variaciones en la composición del disco)
- 22. Corrientes de acreción en la formación de un proto-planeta
- 23. Protoplanetas Para que la gravedad prevalezca sobre la radiación y los planetas grandes mantengan gas, el proceso de formación ha de ser muy rápido (centenares de años, Quinn 2003)
- 24. Formación de un júpiter
- 25. Pero quedan bastantes problemas por resolver
- 26. Problema de la multiplicidad Casi todas las estrellas forman parte de sistemas múltiples (binarias, triples, etc) y casi todas ellas parecen haberse formado en grupos o cúmulos. Porqué las estrellas se forman en grupos ? Qué mecanismo es responsable de la multiplicidad ? Campos magnéticos ? Turbulencia ?
- 27. Problema de las masas estelares Porqué las estrellas tienen las masas que tienen ? Cada nube interestelar no colapsa para formar una única estrella de masa igual a la de la nube “madre” Una nube interestelar forma muchas estrellas de diferentes masas, pero en un rango desde ~ 0.01 hasta ~ 100 Mo Qué mecanismo limita las masas estelares ?
- 38. 2 3 4 5 6 7 8 9 10 11 13 H 2 C 3 c-C 3 H C 5 C 5 H C 6 H CH 3 C 3 N CH 3 C 4 H CH 3 C 5 N? HC 9 N HC 11 N AlF C 2 H l-C 3 H C 4 H l-H 2 C 4 CH 2 CHCN HCOOCH 3 CH 3 CH 2 CN (CH 3 ) 2 CO AlCl C 2 O C 3 N C 4 Si C2H4 CH 3 C 2 H CH 3 COOH? (CH 3 ) 2 O NH 2 CH 2 COOH? C 2 C 2 S C 3 O l-C 3 H 2 CH 3 CN HC 5 N C 7 H CH 3 CH 2 OH CH 3 CH 2 CHO CH CH 2 C 3 S c-C 3 H 2 CH 3 NC HCOCH 3 H 2 C 6 HC 7 N CH+ HCN C 2 H 2 CH 2 CN CH 3 OH NH 2 CH 3 CH 2 OHCHO C8H CN HCO CH 2 D+? CH 4 CH 3 SH c-C 2 H 4 O CH 2 CHCHO CO HCO + HCCN HC 3 N HC 3 NH+ CH 2 CHOH CO + HCS+ HCNH+ HC 2 NC HC 2 CHO CP HOC+ HNCO HCOOH NH 2 CHO Csi H 2 O HNCS H 2 CHN C 5 N HCl H 2 S HOCO+ H 2 C 2 O KCl HNC H 2 CO H 2 NCN NH HNO H 2 CN HNC 3 NO MgCN H 2 CS SiH 4 NS MgNC H 3 O + H 2 COH + NaCl N 2 H+ NH 3 OH N 2 O SiC 3 2 3 PN NaCN SO OCS SO+ SO 2 SiN c-SiC 2 SiO CO 2 SiS NH 2 CS H 3 + HF SiCN SH AlNC FeO (?)
- 41. Escherichia coli t = 10.000 M. años vida en la Tierra (bacterias)
- 42. t = 13.000 M. años organismos multicelulares
- 43. t = 13.640 M. años extinción de los dinosaurios
- 44. t = 13.690 M. años (hace 10 M años) Austrolopitecus en Africa
- 48. Imagen artística de 51 Pegasi b y su estrella
- 49. Cambios en velocidad, posición y brillo
- 50. Métodos de detección de planetas extrasolares: V radial astrometría tránsitos microlente imagen directa
- 54. Los primeros sistemas planetarios extrasolares 51 Peg, Mayor & Queloz (1995)
- 55. Desde 1995 se han detectado 405 planetas extrasolares (Dic 2009) Más de 300 sistemas planetarios (más de 20 múltiples)
- 56. Exoplanetas hasta el 1/12/2009 (vel. radial=azul, tránsitos= verde, timing= violeta, imagen= rojo, astrometría=amarillo, microlentes=naranja,pulsar timing= violeta claro)
- 57. M/M J Exoplanetas hasta el 1/12/2009 (vel. radial=azul, tránsitos= verde, timing= violeta, imagen= rojo, astrometría=amarillo, microlentes=naranja,pulsar timing= violeta claro) a (AU) 0,1 10 0,01 100 1 1 0,1 10 100
- 58. El espectrógrafo HARPS High Accuracy Radial Velocity Planet Searcher en el telescopio de 3,6 m en La Silla (ESO, Chile) resolución: 1m/s
- 62. HR 4796 A Un disco circunestelar intermedio y dos planetas hipotéticos
- 63. Imagen artística de 51 Pegasi b ( Bellerophon ) y su estrella Un “júpiter caliente”
- 64. 55 Cancri al menos 5 planetas (el único f )
- 65. OGLE-05-390L b Masa 5 M tierra , 3 AU, T=-200 C
- 66. Órbitas de HD 179949 b, HD 164427 b, Epsilon Reticuli Ab, Mu Arae b, comparadas con el sistema solar
- 68. COROT 7b La super-Tierra más pequeña (1,7 Mtierra, 0,02 AU)
- 69. Gleise 581 e super-Tierra con 1,9 Mtierra, 0,03 AU) estrella enana marrón @ 20 años-luz 21/4/09 (HARPS)
- 70. HR 8799 b,c,d Primer sistema planetario detectado con múltiples planetas por imagen directa (2008)
- 71. 19 de octubre 2009 ¡32 planetas!
- 73. Planetas en torno a púlsares
- 74. Vida en otros planetas ?
- 75. ¿ Hay vida fuera del sistema solar ?
- 77. Un júpiter caliente con atmósfera (cf. Spitzer)
- 78. Primera atmósfera detectada (2007). Agua y moléculas orgánicas (CH4) HD 189733 b
- 80. Espresso: Super-HARPS en el VLT
- 81. CODEX: super-HARPS en el E-ELT
- 83. Proyectos para detectar más planetas: Darwin, Terrestrial Planet Finder
- 86. ¡ Muchas gracias !
- 89. Hay varios cuerpos del Sistema Solar que pueden cumplir las 3 condiciones de la vida o que pudieron cumplirla en el pasado
- 92. Europa El mayor de los satélites de Jupiter, sólo algo mayor que la Luna
- 93. Vida bajo la superficie helada de Europa ? 1.- Agua líquida Superficie muy agrietada de 150-300 km de hielo puro. Interior quizás más caliente ? (radioactividad, mareas, etc) Oceáno líquido subyacente ? (cf. Fisuras que sugieren desplazamientos de placas) 2.- Energía Posible actividad volcánica (~Luna hace 3 109 años) 3.- Elementos biogenéticos Probablemente disponibles en el interior
- 95. 1.- Energía: volcanismo + radiación solar 2.- Elementos biogenéticos : OK 3.- Agua líquida ? Demasiado caliente ! T ~ 500 C. Si hubo agua en la atmósfera, se perdió en el espacio. Pero: quizás el Sol fue algo menos brillante (30 veces) hace 4 109 años, T ~ 100 C, y algunos organismos pudieron llegar a formarse ? Vida en Venus ?
- 96. Tamaño similar a Mercurio. Atmósfera: muy espesa: N, CH4, C2H6 Fuerte actvidad en química orgánica Océanos líauidos (cf. Huygens) 1.- Elementos biogenéticos : OK 2.- Energía: pudo proceder de impactos de meteoritos (E kin) 3.- Agua líquida ? Demasiado frío ! T ~ -180 C. Pero pudo haberla tenido antes (ej.: en regiones de grandes impactos...) Vida en Titán ?
Notas del editor
- Explanation: Some features of HH-34 are understood -- some are not. At the core of Herbig-Haro 34 lies a seemingly typical young star. This star, though, somehow ejects energetic "bullets" of high-energy particles , appearing as red streaks toward the lower right of the this image . Astronomers speculate that a burst of these particles might rebound when gas from a disk surrounding the star momentarily collapses onto the star. Visible near the end of each light-year long jet is a glowing cap. HH-34 lies about 1500 light-years away in the Orion Nebula star-forming region . The cause of the large arc of gas on the upper left known as the waterfall remains unexplained.
- Explanation: A cloud of interstellar gas and dust collapses and a star is born . At its core temperatures rise, a nuclear furnace ignites , and a rotating dusty disk forms surrounding the newborn star. According to current understanding , as material continues to fall onto the disk it is heated and blasted back out along the disk's axis of rotation, forming a pair of high speed jets. This Hubble Space Telescope image shows two nebulosities at the ends of opposing jets from a young star. The bright blobs at either end are where the jet material has slammed into interstellar gas. Tip to tip, the distance is about one light-year. Located near the Orion Nebula , these nebulosities have catalog designations HH1 and HH2 for their discoverers astronomers George Herbig and Guillermo Haro. The nascent star which produced the jets is in the middle, hidden by a cloud of obscuring dust. Yet the structures and details visible in the star jets offer clues to events which also occured in our own Solar System - when the Sun was formed from a collapsing interstellar cloud 4.5 billion years ago.
- Native bacteria (E. coli), thin-layer preparation, mirror objective WI 125 x, ocular 12,5 x luminance dark field
- Astrolopitecus
- 51 Pegasi b orbita en torno a una estrella G5 más cerca que la distancia Mercurio-Sol . Es un planeta mucho mayor que la Tierra
- Most known exoplanets orbit stars roughly similar to our own Sun , that is, main-sequence stars of spectral categories F, G, or K. One reason is simply that planet search programs have tended to concentrate on such stars. But even after taking this into account, statistical analysis suggests that lower-mass stars ( red dwarfs , of spectral category M) are either less likely to have planets or have planets that are themselves of lower mass and hence harder to detect. [25] Recent observations by the Spitzer Space Telescope indicate that stars of spectral category O, which are much hotter than our Sun, produce a photo-evaporation effect that inhibits planetary formation. [26] Las estrellas de alta metalicidad tienden a tener mayor número de planetas
- Bar chart of exoplanet discoveries by year, through 2009-11-28, indicating the discovery method using distinct colors ( radial velocity = dark blue, transit = dark green, timing = dark purple, astrometry = dark yellow, direct imaging = dark red, microlensing = dark orange, pulsar timing = purple) .
- Solo hay diez planetas conocidos con masas < 10 tierras. Todos los otros son mucho más masivos, incluso muchos más masivos que Jupiter EFECTO DE SELECCION ! De cqada 14 estrellas tiene planetas gigantes, pero una de cada 3 tiene planetas de masa < 30 Masa tierra GRANDES EXCENTRICIDADES:: MISTERIO. Quizás un par de planetas en órbitas circulares simulan un única planeta en elíptica Orbitas muy cercanas < Júpiter::: EFECTO SELECCION Scatter plot of mass, m , and semimajor axis, a , for exoplanet discoveries through 2009-11-28, indicating the discovery method using distinct colors ( radial velocity = dark blue, transit = dark green, timing = dark purple, astrometry = dark yellow, direct imaging = dark red, microlensing = dark orange, pulsar timing = purple), with Solar System planets indicted for reference (in white with gray outlines). Estimates (see &quot;important note&quot; below) of m and a are indicated with circles, or with small triangles where no a value is provided in the Extrasolar Planets Encyclopaedia, and none can be calculated (from given stellar mass and period). Scales indicate (log10 of) mass, m , expressed as Jupiter masses (left) and Earth masses (right); and semimajor axis, a , expressed in AU (bottom), and the corresponding period, p for a planet orbiting a Sun-mass star, expressed in Earth years . Reference lines are provided as a rough measure of the difficulty of detecting exoplanets using radial velocity and transits. Dashed lines trace the combinations of m and a values that produce the indicated radial velocity semi-amplitude K for a planet orbiting a solar-mass star (assuming m << M). Dotted lines trace the m (for Jupiter-density) and a values where the geometric probability of transit for a solar-radius star (assuming a circular orbit, so that e and ω can be ignored) is the indicated value (less than the indicated proportion of all planets to the right of a given line will have transiting orbits). Base data is from the Extrasolar Planets Encyclopaedia [1] , augmented with discovery methods from the Planetary Society 's Catalog of Exoplanets [2] . Occasional missing data is determined from original papers cited by these sources. Important note: This figure is intended to serve as a catalog of generally accepted candidate exoplanets using the distribution of some of their basic properties related to detection. No attempt has been made to characterize the degree of confidence (which varies widely) in the existence of a given planet or its properties. Nor is any attempt made to convey systematic errors associated with a particular method. In particular, the indicated mass, m , for an exoplanet characterized using radial velocity is the minimum mass .
- 2008; Fomalhaut b On November 13, NASA and the Lawrence Livermore National Laboratory announced the discovery of an extrasolar planet orbiting just inside the debris ring of the A class star Fomalhaut (Alpha Piscis Austrini). This was the first extrasolar planet to be directly imaged by an optical telescope. [59] The mass of Fomalhaut b is estimated to be 3 times the mass of Jupiter. [
- Varias veces más masiva que el Sol y a unos 300 años-luz de distancia, en la constelación de Libra, la estrella HR 4796 A posee un disco circunestelar que es intermedio entre los encontrados en estrellas jóvenes (como T Tauri) y los de las estrellas maduras (como Vega). Parece muy posible que se formen planetas en este disco. La ilustración muestra a dos planetas hipotéticos formados en los bordes interior y exterior del disco.
- Mencionar el nombre del planeta. No es oficial. La iAU no ha dado reglas para nombrar a los planetas extrasolares. Debería atacarse a este problema, pero quizás tema episodios del tipo del de PLUTON
- Imagen artística del planeta OGLE-05-390Lb. Con una masa cinco veces superior a la Tierra, este planeta orbita a una distancia de su estrella (una enana roja) que es tres veces mayor que la distancia Tierra-Sol. La temperatura estimada en la superficie de este planeta es por tanto muy baja, del orden de unos 200 grados Celsius bajo cero.
- Our inner solar system superimposed behind the orbits of the planets HD 179949 b , HD 164427 b , Epsilon Reticuli Ab , and Mu Arae b (all parent stars are in the center)
- The first planet found around a brown dwarf . The planet is also the first to be directly imaged (in infrared ). According to an early estimate, it has a mass 5 times that of Jupiter; other estimates give slightly lower masses. It orbits at 55 AU from the brown dwarf. The brown dwarf is only 25 times as massive as Jupiter. The temperature of the gas giant planet is very high (1250 K), mostly due to gravitational contraction. [40] In late 2005, the parameters were revised to orbital radius 41 AU and mass of 3.3 Jupiters, because it was found that the star is closer to Earth than was originally believed. In 2006, a dust disk was found around 2M1207, providing evidence for active planet formation
- COROT-7b On February 3, the European Space Agency announced the discovery of a planet orbiting the star COROT-7 . Although the planet orbits its star at a distance less than 0.02 AU, its diameter is estimated to be around 1.7 times that of Earth, making it the smallest super-Earth yet measured. Due to its extreme closeness to its parent star, it is believed to have a molten surface at a temperature of 1000–1500 °C . [63] It was discovered by the French COROT satellite. COROT-7b was found by the observation of a brightness change of its mother star, originating in a transit of the planet in front of the star (as seen from Earth). The exact knowledge of the brightness difference, together with a size estimate for the star, allows one to calculate the planet's size. The discovery of COROT-7b was announced on 3 February 2009, during the COROT Symposium 2009 in Paris . [9] It will be published in a forthcoming special issue of the journal Astronomy and Astrophysics dedicated to results from COROT. [10] [ edit ] Characteristics Size comparison EarthCOROT-7b The planet has a maximum surface temperature between 1800 to 2600 °C (3300 to 4700 degrees Fahrenheit). [2] Due to the high temperature, it may be covered in lava . [3] The composition and density of the planet are still being examined, with one possibility being that it is rocky like Earth. It may also belong to a class of planets that are thought to contain up to 40% water (in the form of ice and/or vapor) in addition to rock. [2] However, the fact that it formed so close to its parent star may mean that it is depleted of volatiles. [11] A strong possibility exists that the planet's rotation is tidally locked to the orbital period, so that temperatures and geologic conditions on the sides of the planet facing towards and away from the star may be dramatically different. Theoretical work also suggests that CoRoT-7b could be a Chthonian planet (the remains of a Neptune-like planet from which much of the initial mass has been removed due to close proximity to its parent star.) [12] With an orbital period of just 20 hours, the planet has the shortest orbit ever seen in any planet, extrasolar or otherwise. [13] According to Suzanne Aigrain , a researcher at the University of Exeter who is part of the COROT team, the planet is much more earthlike than previously found exoplanets and probably has a solid surface somewhere. [13] [ edit ] Possible atmosphere Due to the high temperatures on the illuminated side of the planet, and the likelihood that all surface volatiles have been depleted, silicate rock vaporization may have produced a tenuous (with a pressure approaching 10−2 bar at 2500 K) atmosphere consisting predominantly of sodium , O2 , O and silicon monoxide , as well as smaller amounts of potassium and other metals. [11] [6] Mg , Al , Ca , Si , and Fe may rain out from such an atmosphere on the planet's daylight side in the form of particles of minerals, such as enstatite , corundum and spinel , wollastonite , silica , and iron (II) oxide , that would condense at altitudes below 10 km. Ti may be depleted (and possibly Fe similarly) by being transported towards the night side before condensing as perovskite and geikelite. [11] Sodium (and to a lesser extent, potassium), being more volatile, would be less subject to condensation into clouds, and would dominate the outer layers of the atmosphere. [11] [6]
- Gliese 581 e (pronounced /ˈ ɡliːzə / ) or Gl 581 e is the fourth extrasolar planet found around Gliese 581 , an M3V red dwarf star approximately 20.5 light-years away from Earth in the constellation of Libra . The planet was discovered by an Observatory of Geneva team lead by Michel Mayor , using the HARPS instrument on the European Southern Observatory 3.6 m (140 in) telescope in La Silla , Chile . The discovery was announced on 21 April 2009 . Mayor's team employed the radial velocity technique, in which the orbit size and mass of a planet are determined based on the small perturbations it induces in its parent star's orbit via gravity . [1] At a minimum of 1.9 Earth masses , it is the smallest extrasolar planet discovered around a normal star, and the closest in mass to Earth. At an orbital distance of just 0.03 AU from its parent star, however, it is outside the habitable zone . It is unlikely to possess an atmosphere due to its high temperature and strong radiation from the star. From this planet, the star would appear more than 10 times larger in the sky than the Sun does appear from Earth and shine about 4 times brighter at a magnitude of about -27.[ citation needed ] Although scientists think it probably has a rocky surface similar to Earth, it is also likely to experience intense tidal heating similar to (and likely more intense than) that affecting Jupiter's moon Io . [2] Gliese 581e completes an orbit of its sun in approximately 3.15 days
- HR 8799 HR 8799 (center blob) with HR 8799d (bottom), HR 8799c (upper right), HR 8799b (upper left) Observation data Epoch J2000.0 Equinox J2000.0 ( ICRS ) Constellation Pegasus Right ascension 23h 07m 28.7150s [1] Declination +21° 08′ 03.302″ [1] Apparent magnitude (V) 5.964 [1] Characteristics Spectral type kA5 hF0 mA5 V; λ Boo [2] [3] U-B color index −0.04 [4] B-V color index 0.234 [1] Variable type Gamma Doradus variable [1] Astrometry Radial velocity (Rv) −11.5 ± 2 [1] km/ s Proper motion (μ) RA: 107.93 ± 0.60 [5] mas / yr Dec.: −49.63 ± 0.46 [5] mas / yr Parallax (π) 25.38 ± 0.70 [5] mas Distance 129 ± 4 ly (39 ± 1 pc ) Absolute magnitude (MV) 2.98 ± 0.08 [2] Details Mass 1.47 ± 0.30 [2] M ☉ Radius 1.34 ± 0.05 [2] R ☉ Surface gravity (log g ) 4.35 ± 0.05 [2] Luminosity (bolometric) 4.92 ± 0.41 [2] L ☉ Temperature 7430 ± 75 [2] K Metallicity [M/H] = −0.47 ± 0.10 [2] [note 1] Rotational velocity ( v sin i ) 37.5 ± 2 [2] km / s Age 60+100−30 × 106 [6] years Other designations V342 Pegasi , BD +20 5278, FK5 3850, GC 32209, HD 218396, HIP 114189, PPM 115157, SAO 91022, TYC 1718-2350-1. [1] Database references SIMBAD data NStED data Extrasolar Planets Encyclopaedia data HR 8799 is a young (~60 million year old) main sequence star located 129 light years (39 parsecs ) away from Earth in the constellation of Pegasus , with roughly 1.5 times the Sun 's mass and 4.9 times its luminosity. It is part of a system that also contains a debris disk and at least three massive planets (which, along with Fomalhaut b , were the first extrasolar planets whose orbital motion was confirmed via direct imaging ). The designation HR 8799 is the star's identifier in the Bright Star Catalogue . The star is a Gamma Doradus variable : its luminosity changes because of non-radial pulsations of its surface. The star is also classified as a Lambda Boötis star , which means its surface layers are depleted in iron peak elements. [2] This may be due to the accretion of metal -poor circumstellar gas. [7] It is the only known star which is simultaneously a Gamma Doradus variable, a Lambda Boötis star, and a Vega -like star (a star with excess infrared emission caused by a circumstellar disk ). [8] Contents [hide] 1 Spectral type and metallicity 2 Planetary system 3 See also 4 Notes 5 References 6 External links [ edit ] Spectral type and metallicity The star HR 8799 is a member of the Lambda Boötis class, a group of peculiar stars with an unusual abundance of metals in the upper atmosphere. Because of this special status, stars like HR 8799 have a very complex spectral type. The shape of the hydrogen line and the star's effective temperature best match the typical spectrum of an F0 V star. However, the strength of the calcium II K line and the metallic lines are more like those of an A5 V star. The star's spectral type is therefore written as kA5 hF0 mA5 V; λ Boo. [2] [3] Detailed analysis of the star's spectrum reveals that it has a slight overabundance of carbon and oxygen compared to the Sun (by approximately 30% and 10% respectively). While some Lambda Boötis stars have sulfur abundances similar to that of the Sun, this is not the case for HR 8799; the sulfur abundance is only around 35% of the solar level. The star is also poor in elements heavier than sodium : for example, the iron abundance is only 28% of the solar iron abundance. [9] Asteroseismic observations of other pulsating Lambda Boötis stars suggest that the peculiar abundance patterns of these stars are confined to the surface only: the bulk composition is likely more normal. This may indicate that the observed element abundances are the result of the accretion of metal-poor gas from the environment around the star. [10] [ edit ] Planetary system On November 13, 2008, Christian Marois of the National Research Council of Canada's Herzberg Institute of Astrophysics and his team announced they had directly observed three planets orbiting the star with the Keck and Gemini telescopes in Hawaii , [8] [11] [12] [13] in both cases employing adaptive optics to make observations in the infrared . A precovery observation of the outermost of the planets was later found in infrared images obtained in 1998 by the Hubble Space Telescope 's NICMOS instrument, after a newly developed image-processing technique was applied. [14] The outer planet orbits just inside a dusty disk like the Solar Kuiper belt . It is one of the most massive disks known around any star within 300 light years of Earth, and there is room in the inner system for terrestrial planets . [12] The orbital radii of planets d , c and b are 2 to 2.5 times those of Saturn , Uranus , and Neptune , respectively. Because of the inverse square law relating radiation intensity to distance from the source, comparable radiation intensities are present at distances = 2.2 times farther from HR 8799 than from the Sun, meaning that corresponding planets in the solar and HR 8799 systems receive similar amounts of stellar radiation. These objects are near the upper mass limit for classification as planets; if they exceeded 13 Jupiter masses , they would be capable of deuterium fusion in their interiors and thus qualify as brown dwarfs under the definition of these terms used by the IAU 's Working Group on Extrasolar Planets. [15] If the mass estimates are correct, the HR 8799 system is the first multiple-planet extrasolar system to be directly imaged. [11] The orbital motion of the planets is in an anticlockwise direction was confirmed via multiple observations dating back to 2004. [8] While the discovery paper suggests that the orbits are circular and observed nearly face-on, dynamical simulations require the masses of the planets to be much lower than assumed, otherwise the system is unstable on timescales much shorter than the age of the star. The system is more likely to be stable if the inner two planets are in a 2:1 resonance, which would imply the innermost planet's orbit has an eccentricity exceeding 0.04 in order to match the observational constraints. Planetary systems with the best-fit masses from evolutionary models would be stable if the planets are in a 1:2:4 orbital resonance (similar to the Laplace resonance between Jupiter's inner three Galilean satellites : Io , Europa and Ganymede ). If confirmed, the HR 8799 planetary system would be the first extrasolar system to be observed with multiple resonances. Such systems would still be stable with planetary masses up to 1.9 times the nominal values. [16] The HR 8799 system [6] [8] Companion (in order from star) Mass Semimajor axis ( AU ) Orbital period ( years ) Eccentricity d 10±3 M J ~ 24~ 100>0.04 [16] [note 2] c 10±3 M J ~ 38~ 190 ? b 7+4−2 M J ~ 68~ 460 ? Dust disk 75 AU Spitzer infrared image of HR 8799's debris disk, January 2009. The small dot in the centre is the size of Pluto's orbit. In January 2009 the Spitzer Space Telescope obtained images of the debris disk around HR 8799. Three components of the debris disk were distinguished: Warm dust (T ~ 150 K) orbiting within the innermost planet A broad zone of cold dust (T ~ 45 K) with a sharp inner edge orbiting just outside the outermost planet A dramatic halo of small grains originating in the cold dust component. The halo is unusual and implies a high level of dynamic activity which is likely due to gravitational stirring by the massive planets. [17] The Spitzer team says that collisions are likely occurring among bodies similar to those in our Kuiper Belt and that the three large planets may not yet have settled into their final, stable orbits. [18] In the photo, the bright, yellow-white portions of the dust cloud come from the outer cold disk. The huge extended dust halo, seen in orange-red, has a diameter of ≈ 2,000 AU. The diameter of Pluto's orbit (≈ 80 AU) is shown for reference as a dot in the centre. [
- On October 19, it was announced that 30 new planets were discovered, all were detected by radial velocity method. It is the most planets ever announced in a single day during the exoplanet era. October 2009 now holds the most planets discovered in a month, which broke the record set back in June 2002 and August 2009 , which they discovered 17 planets.
- Astrónomos del Instituto Max Planck de Astronomía han registrado una imagen directa de un tenue cuerpo celestial que orbita en torno a la estrella GJ 758. Su masa se estima entre diez y 40 veces la de Júpiter, el mayor planeta de nuestro Sistrema Solar. Con una temperatura de unos 330 grados, GJ758 B es el compañero más frío de una estrella como el Sol que ha podido ser captado hasta la fecha de forma diorecta. Se encuentra en la constelación de Lira. Más de 400 exoplanetas han sido censados hasta ahora por los investigadores. La inmensa mayoría de ellos, que orbitan en torno a lejanas estrellas, han sido detectados indirectamente: gracias a la observación de cómo afectan al movimiento o el brillo de su estrella. Es mucho más difícil captar estos planetas directamente ya que se encuentran a años luz de distancia. Nos aparecen muy próximos a sus estrellas y normalmente los eclipsan. Sería como tratar de fotografiar una mosca alrededor de una farola de 300 watios a un kilómetro de distancia. Sin embargo, las imágenes proporcionan información valiosa sobre la órbita del planeta, su temperatura y la composición química de su atmósfera. En la búsqueda de planetas extrasolares, los astrónomos han registrado con éxito imágenes gracias a la fortuna y a un nuevo instrumento. La cámara, llamada HiCIAO, está instalada en el telescopio de 8 metros Subaru del observatorio de Mauna Kea (Hawaii). Los investigadores utilizaron lo último en ótica adaptiva para neutralizar el destello causado por las turbulencias del aire. Aunque cada imagen individual de la débil señal del planeta está atenuada por el halo residual de la estrella central, una ingeniosa combinación de secuencias de tiempo de imágenes individuales, denominada 'Angular Differential Imaging' (ADI), ha capacitado a los astrónomos para suprimir el halo de la estrella central de tal forma que el débil destello de GJ 758 B fue visible en la imagen final. Antes de este descubrimiento, sólo diez posibles exoplanetas habían sido captados directamente. Las condiciones en esos sistemas difieren enormemente del nuestro: cada planeta orbita a su estrella central a una gran distancia o la temperatura del exoplaneta es mayor de 1.000 grados y esto se corresponde más con la temperatura de una estrella que de un planeta. En comparación con otros candidatos, GJ 758B tiene mucho más en común con los grandes planetas de nuestro sistema: orbita una estrella como el Sol a una distancia que corresponde a la de los planetas exteriores de nuestro sistema. Pero lo más interesante es la temperatura relativamente baja de este supuesto planeta, que está entre los 270 y los 370 grados centígrados. &quot;Esto corresponde a la temperatura de la cara dirigida al Sol de Mercurio&quot;, declaró Christian Thalmann, del Instituto Max Planck de Astronomía. Asi, &quot;GJ 758 B es de esta forma el exoplaneta en torno a una estrella como el Sol más frío que ha sido detectado hast ahora&quot;. dijo.
- PERO EN TERMINOS GENERALES EL AGUA ES ESCASA HD 189733 b On March 20, follow up studies to the first spectral analyses of an extrasolar planet were published in the scientific journal Nature , announcing evidence of an organic molecule found on an extrasolar planet for the first time. In 2007 water vapor was already detected in the spectrum of HD 189733 b , but new analyses showed not only water vapor, but also methane existing in the atmosphere of the giant gas planet. Although conditions on HD 189733 b are too harsh to harbor life, it still is the first time a key molecule for organic life was found on an extrasolar planet. HD 189733 b From Wikipedia, the free encyclopedia Jump to: navigation , search HD 189733 b Extrasolar planet List of extrasolar planets An artist's impression of HD 189733 b Parent star Star HD 189733 A Constellation Vulpecula Right ascension ( α )20h 00m 43.7133s Declination ( δ )+22° 42′ 39.070″ Apparent magnitude ( mV )7.66 Distance 62.9 ly (19.3 pc ) Spectral type K1-K2V Orbital elements Semimajor axis ( a )0.03099 ± 0.0006 AU (4.636 ± 0.09 Gm ) Periastron ( q )0.03096 AU (4.632 Gm ) Apastron ( Q )0.03102 AU (4.641 Gm ) Eccentricity ( e )0.0010 ± 0.0002 Orbital period ( P )2.2185733 ± 0.00002 d (0.006074 y ) Orbital speed ( υ )152.5 km/s Inclination ( i )85.76 ± 0.29° Time of transit ( Tt )2,453,988.80336 ± 0.00024 JD Semi- amplitude ( K )205 ± 6 m/s Physical characteristics Mass ( m )1.13 ± 0.03 M J Radius ( r )1.138 ± 0.027 R J Surface gravity ( g )21.2 m/s² Temperature ( T )1117 ± 42 K Discovery informationDiscovery date 5 October 2005 Discoverer(s) Bouchy et al. Detection method Doppler spectroscopy Transit Discovery site Haute -Provence Observatory Discovery status Confirmed Database references Extrasolar Planets Encyclopaedia data SIMBAD data HD 189733 b is an extrasolar planet approximately 63 light-years away in the constellation of Vulpecula (the Fox ). The planet was discovered orbiting the star HD 189733 on October 5, 2005, when astronomers in France observed the planet transiting across the face of the star. [1] The planet is classified as a hot Jupiter class Jovian planet , with a close orbit to its parent star. HD 189733 b was the first extrasolar planet to be mapped and the first to be discovered with carbon dioxide in its atmosphere. Contents [hide] 1 Detection and discovery 1.1 Transit and Doppler spectroscopy 1.2 Infrared spectrum 2 Satellites 3 Physical characteristics 3.1 Map of the planet 3.2 Water vapor and organic compounds 3.3 Evolution 4 See also 5 References 6 External links [ edit ] Detection and discovery [ edit ] Transit and Doppler spectroscopy On October 6, 2005, a team of astronomers announced the discovery of transiting planet HD 189733 b. The planet was initially detected using Doppler spectroscopy . Real-time radial velocity measurements detected the Rossiter -McLaughlin effect caused by the planet passing in front of its star before photometric measurements confirmed that the planet was transiting. In 2006, a team led by Drake Deming announced a detection of strong infrared thermal emission from the transiting extrasolar planet HD 189733 b, by measuring the flux decrement (decrease of total light) during its prominent secondary eclipse (when the planet passes behind the star). Size comparison JupiterHD 189733 b The mass of the planet is estimated to be 13% larger than Jupiter's ; with the planet completing an orbit around its host star every 2.2 days and an orbital speed of 152.5 km/s. It is occasionally referred to as HD 189733 Ab to distinguish it from the red dwarf star HD 189733 B. The HD 189733 star system is 63 light years from Earth in the direction of the constellation Vulpecula . [ edit ] Infrared spectrum On February 21, 2007, NASA released news that the Spitzer Space Telescope had measured detailed spectra from both HD 189733 b and HD 209458 b . [2] The release came simultaneously with the public release of a new issue of Nature containing the first publication on the spectroscopic observation of the other exoplanet, HD 209458 b. A paper was submitted and published by the Astrophysical Journal Letters . The spectroscopic observations of HD 189733 b were led by Carl Grillmair of NASA's Spitzer Science Center . The infrared spectrum of HD 189733 b. On October 22, a team of astrophysicists at the ETH Zürich managed to &quot;detect and monitor [its] visible light&quot; using polarimetry , the first such success. The authors claim a radius of 1.5+/-.2 Rj: over 30% larger than its transit disc. Its albedo in blue light is greater than 0.14. The planet would appear deep blue to our eyes. [3] [4] This work will need to be confirmed, however, as the estimated radius is much larger than expected from measurements at other wavelengths. The blueness of the planet may be the result of Rayleigh scattering . In mid January 2008, spectral observation during the planet's transit using that model found that if molecular hydrogen exists, it would have an atmospheric pressure of 410 ± 30 mbar of 0.1564 solar radii. The Mie approximation model also found that there is a possible condensate in its atmosphere, magnesium silicate (MgSiO3) with a particle size of approximately 10−2 to 10−1 μm. Using both models, the planet's temperature would be between 1340 to 1540 K. [5] The Rayleigh effect is confirmed in other models, [6] and by the apparent lack of a cooler, shaded stratosphere below its outer atmosphere. [ edit ] Satellites The transits reveal no moons of 0.8 Earth radius or larger, and no ring system comparable to Saturn's. [7] [ edit ] Physical characteristics An artist's impression of the planet that is in agreement with the global temperature map. This planet exhibits the largest photometric transit depth (amount of the parent star's light blocked) of any extrasolar planet so far observed, of approximately 3%. The apparent longitude of ascending node of its orbit is 16 degrees +/- 8 away from north-south in our sky. It and HD 209458 b were the first two planets to be directly spectroscopically observed. [2] The parent stars of these two planets are the brightest transiting-planet host stars, so these planets will continue to receive the most attention by astronomers. Like most hot Jupiters, this planet is thought to be tidally locked to its parent star, meaning it has a permanent day and night. The planet is not oblate . The atmosphere was at first predicted &quot;pL class&quot;, lacking a temperature-inversion stratosphere ; like L dwarfs which lack titanium and vanadium oxides. [8] Followup measurements, tested against a stratospheric model, yielded inconclusive results. [9] The condensates form a haze 1000 km above the surface as viewed in the infrared. A sunset viewed from that surface would be red. [10] Sodium and potassium signals were predicted by Tinetti 2007. These signals were at first obscured by the condensate haze. Sodium was then found at three times the level of HD 209458 b . [11] This is the first extra solar planet discovered to have carbon dioxide in the atmosphere. [12] [ edit ] Map of the planet In 2007, the Spitzer space telescope was used to map the planet's temperature emissions. The planet+star system was observed for 33 consecutive hours, starting when only the night side of the planet was in view. Over the course of one-half of the planet's orbit, more and more of the day side came into view. A temperature range of 973 ± 33 K to 1,212 ± 11 K was discovered, indicating that the absorbed energy from the parent star is distributed fairly evenly through the planet's atmosphere. Interestingly, the region of peak temperature was offset 30 degrees east of the substellar point, as predicted by theoretical models of Hot Jupiters taking into account a parameterized day to night redistribution mechanism [13] . The global temperature map of HD 189733 b. Assuming the planet is tidally locked with its star, this suggests that powerful easterly winds moving at more than 9,600 kilometers per hour are responsible for redistributing the heat. [14] NASA released a brightness map of the surface temperature of HD 189733 b; it is the first map ever published of an extra-solar planet. [15] [ edit ] Water vapor and organic compounds On July 11, 2007, a team lead by Giovanna Tinetti published the results of their observations using the Spitzer Space Telescope concluding there is solid evidence for significant amounts of water vapor in the planet's atmosphere. [16] Follow-up observations made using the Hubble Space Telescope confirm the presence of water vapor and also the organic compound methane . [6] [17] It is currently unknown how the methane originated as the planet's high temperature (700°C, 1292°F) should cause the water and methane to react, replacing the atmosphere with carbon monoxide . [17] [18] [ edit ] Evolution While transiting the system also clearly exhibits the Rossiter -McLaughlin effect , the shifting in photospheric spectral lines caused by the planet occulting a part of the rotating stellar surface. Due to its high mass and close orbit the parent star has a very large semi-amplitude (K) , the &quot;wobble&quot; in the star's radial velocity , of 205 m/s. [19] The Rossiter -McLaughlin effect allows the measurement of the angle between the planet's orbital plane and the equatorial plane of the star. These are well aligned. [20] By analogy with HD 149026 b , the formation of the planet was peaceful and probably involved interactions with the protoplanetary disc . A much larger angle would have suggested a violent interplay with other protoplanets.
- Las franjas luminosas son debidas al reflejo de lus solar por la propia sonda. Voyager había ya pasado Jupiter y Saturno (que esta a 1400 millones de km).
- Esta imagen tiene 40 años, pero no por vieja es menos emocionante. Y es emocionante por que allá a lo lejos desde la soledad de la luna, se divisa nuestro planeta, nuestro hogar. El planeta evoca soledad (estamos realmente solos?) y fragilidad (hasta cuando nos durará?) Pero sobre todo esta imagen nos recuerda que vivimos sobre un planeta, un planeta que tiene su sitio en el sistema solar, en el contexto cósmico.