Una visión diferente para disfrutar de la magia del Universo
Astronomía - Cosmología - Astrofotografía - Astrofísica - Exploración Espacial

💫Nuevo!! Universo Mágico muestra los catálogos astronómicos más populares. Búscalos en la barra superior de navegación y lateral.

💫Los aficionados ya pueden escribir sobre astronomía. Date de alta como Autor en Universo Mágico Público.

 ðŸ’«Si eres Autor prueba la opción Nueva Entrada

💫Grupos en Facebook: Astroimaging - Stars in the Sky - Astronomy Plus - Astrophotographers

💫Wide-field image of the NGC 2808

Communities & Groups:     (New)  Space World Google+        Big Bang Facebook



New observations by the NASA/ESA Hubble Space Telescope have overturned conventional ideas about the early life of some massive globular clusters, showing that they can go through several periods of intense stellar formation rather than the previously accepted single burst. The analysis of Hubble data from the massive globular cluster NGC 2808 provides evidence that star birth occurred over three generations early in the cluster's life. "We had never imagined that anything like this could happen," said Giampaolo Piotto of the University of Padua in Italy and leader of the team that made the discovery. "This is a complete shock." Globular clusters are among the earliest settlers of our Milky Way Galaxy, born during our Galaxy's formation. A typical cluster consists of hundreds of thousands of stars held together by gravity in a compact swarm. "The standard picture of a globular cluster is that all of its stars formed at the same time, in the same place, and from the same material, and that they have co-evolved for billions of years," said team member Luigi Bedin of ESO in Garching, Germany, the European Space Agency, and Space Telescope Science Institute in Baltimore, USA. "This is the cornerstone on which much of the study of stellar populations has been built. So we were very surprised to find several distinct populations of stars in NGC 2808. All of the stars were born within 200 million years very early in the life of the 13-billion-year-old massive cluster."




Finding multiple stellar populations in a globular cluster so close to home has deep cosmological implications, the researchers said. "We need to do our best to solve the enigma of these multiple generations of stars found in these Hubble observations so that we can understand how stars formed in distant galaxies in our early Universe," Piotto explained. The astronomers used Hubble's Advanced Camera for Surveys to measure the brightness and colour of the cluster stars. Hubble's exquisite resolution allowed the astronomers to sort out the different stellar populations. The Hubble measurements showed three distinct populations, with each successive generation appearing slightly bluer. This colour difference suggests that successive generations contain a slightly different mix of some chemical elements. "One assumption, although we have no direct proof," said team member Ivan King of the University of Washington in Seattle, USA, "is that the amount of helium increases with each generation of stars. The successively bluer colour of the stellar populations indicates that the amount of helium increases in each generation. Perhaps massive star clusters like NGC 2808 hold onto enough gas to ignite a rapid succession of stars." The star birth would be driven by shock waves from supernovae and stellar winds from red giant stars, which compress the gas and make new stars, King explained. The gas would be increasingly enriched in helium from previous generations of stars more massive than the Sun.

Astronomers commonly assumed that globular clusters produce only one stellar generation because the energy radiating from the first batch of stars would clear out most of the residual gas needed to make more stars. But a hefty cluster like NGC 2808 is two to three times more massive than a typical globular cluster and may have sufficient gravity to hang onto enough gas, which is then enriched by helium from the first stars. Of the about 150 known globular clusters in our Milky Way Galaxy, NGC 2808 is one of the most massive, containing more than 1 million stars. Another possible explanation for the multiple stellar populations is that NGC 2808 may only be masquerading as a globular cluster. The stellar grouping may have been a dwarf galaxy that was stripped of most of its material due to gravitational capture by our Milky Way. Omega Centauri, the first globular cluster Piotto's group found to have multiple generations of stars, is suspected to be the remnant core of a dwarf galaxy, Bedin said. Although the astronomers have searched only two globular clusters for multiple stellar populations, they say this may be a typical occurrence in other massive clusters. "No one would make the radical step of suggesting that previous work on other clusters is no longer valid," King said. "But this discovery shows that the study of stellar populations in globular clusters now opens up in a new direction."

Credit: Davide De Martin (ESA / Hubble), the ESA / ESO / NASA Photoshop FITS Liberator & Digitized Sky Survey 2


Communities & Groups:     (New)  Space World Google+        Big Bang Facebook

Publicar un comentario






Para visualizar correctamente este sitio web utiliza un navegador basado en Chromium, o Fire Fox. Si te gusta la privacidad se recomienda utilizar Tor Browser.
Para la correcta visualización de la página de Husos Horarios utiliza Internet Explorer.

universo cosmos espacio astonomía cosmología exploración espacial astrofotografía astrofotógrafo astrónomo cosmólogo nebulosa galaxia nube oscura brillante estrella estrellas cúmulo estelar abierto globular planeta sol mercurio venus tierra marte júpiter saturno urano neptuno plutón ceres fobos deimos luna titán encelado europa calisto ganímedes ío caronte hydra nix cometa asteroide cinturón grupo galáctico supercúmulo planetaria emisión reflexión absorción polvo gas atmósfera rayos X gamma cuásar púlsar herbig-haro constelación asterismo fugaces meteoros meteoritossatélite iss estación cohetetelescopio hubble chandra spitzer nustar xmm-newton most very vlt vla vst vista herschel soar ssro sloan rosetta rosat philae osiris subaru campanas kitt keck wilson observatorio palomar calar horizons voyager mpg mycron merlin maven express mariner magellan juno grand canarias gemini hawk galileo galex gaia fuse digited dawn clementine cassini apolo apex alma agujero agujeros polo norte sur sistema solar vacío local big bang oculta coronalunar solar cráter superluna sangre eclipse total parcial ocultación luminiscencia refracción destello anular tránsito protuberancia filamento mancha manchas solares andrómeda messier enana física físico ngc ic trío arp melotte doradus barnard pilares trompa burbuja nuro cabeza cisne cygnus sh2 shapley mz rho sagittarius tarántula magallanes gran pequeña triángulo pickering torre variable binaria espectroscópica bennu thule carinae cygnicom coma virgo cuarteto quinteto cadena energía color markarian tritón molecular supernova nova remanente explosión frente choque einstein caldwell darwin huygens ptolomeo halley piggot gillett hale riccioli gentil newton bode kepler dreyer harding copérnico lacaille loys pierre hawking ciencia científicos cielo arcoiris lenticular espiral elíptica barrada brazo brazos región regiones vdb rcw año luz parsec grado grados celsius farenheit kelvin minuto minutos arco arcominutos oculta llena oscura partículas átomo átomos temperatura millones miles luz espectro universe cosmos space astonomy cosmology space exploration astrophotography astrophotographer astronomer cosmologist nebula galaxy cloud dark shining star stars star cluster open globular planet sun mercury venus earth mars jupiter saturn uranus neptune pluto ceres fobos deimos moon titan waxed europe calist ganymede charontera hydra nix comet aste group hydra nix comet aste group hydra nix comet band galactic planetary supercluster emission reflection absorption dust gas atmosphere x-ray gamma quasar pulsar herbig-haro constellation asterism fleeting meteor meteorite satellite iss station rockettelescope hubble chandra spitzer nustar xmm-newton most very vlt vla vst view herschel soar ssro sloan rosetta rostar ketar keckar ketar ketar ketar subtle rosat ketar roster ketsar keta subar kitty wilson observatory pigeon jello horizons voyager mpg mycron merlin maven express mariner magellan juno grand canarias gemini hawk galileo galex gaia fuse digited dawn clementine cassini apollo apex soul hole aguj eros north pole south solar system empty local big bang hidden coronalunar solar crater supermoon blood eclipse total partial concealment luminescence refraction ring flash transit protuberance filament spot sunspots andromeda messier dwarf physical physics ngc ic trio arp melotte doradus barnard pillars trunk nuro head swan cygnus sh2 shapley mz rho sagittarius tarantula magallanes large small triangle pickering variable tower binary spectroscopic bennu thule carinae cygnicom coma virgo quartet quintet chain energy color markarian molecular triton supernova nova remnant explosion front shock shock einstein caldwell darwin huygens ptolomeo halley piggot gyerton keplentil dd gillett harder keterton gilton kepleton dilton graveyard copernicus lacaille loys pierre hawking science scientists sky rainbow lenticular spiral elliptic barred arm arms region regions vdb rcw year light parsec degree degrees celsius farenheit kelvin minute minutes arc minute arch hidden full dark particles atom atoms temperature millions thousand light spectrum