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Wednesday, September 17, 2014

Hubble Finds Companion Star Hidden for 21 Years in a Supernova's Glare


News Release Number: STScI-2014-38

Hubble Finds Companion Star Hidden for 21 Years in a Supernova's Glare

The full news release story:


Astronomers using NASA's Hubble Space Telescope have discovered a companion star to a rare type of supernova. This observation confirms the theory that the explosion originated in a double-star system where one star fueled the mass-loss from the aging primary star.

This detection is the first time astronomers have been able to put constraints on the properties of the companion star in an unusual class of supernova called Type IIb. They were able to estimate the surviving star's luminosity and mass, which provide insight into the conditions that preceded the explosion.

"A binary system is likely required to lose the majority of the primary star's hydrogen envelope prior to the explosion. The problem is that, to date, direct observations of the predicted binary companion star have been difficult to obtain since it is so faint relative to the supernova itself," said lead researcher Ori Fox of the University of California (UC) at Berkeley.

Astronomers estimate that a supernova goes off once every second somewhere in the universe. Yet they don't fully understand how stars explode. Finding a "smoking gun" companion star provides important new clues to the variety of supernovae in the universe. "This is like a crime scene, and we finally identified the robber," quipped team member Alex Filippenko, professor of astronomy at UC Berkeley. "The companion star stole a bunch of hydrogen before the primary star exploded."

The explosion happened in the galaxy M81, which is about 11 million light-years away from Earth in the direction of the constellation Ursa Major (the Great Bear). Light from the supernova was first detected in 1993, and the object was designated SN 1993J. It was the nearest known example of this type of supernova, called a Type IIb, due to the specific characteristics of the explosion. For the past two decades astronomers have been searching for the suspected companion, thought to be lost in the glare of the residual glow from the explosion.

Observations made in 2004 at the W.M. Keck Observatory on Mauna Kea, Hawaii, showed circumstantial evidence for spectral absorption features that would come from a suspected companion. But the field of view is so crowded that astronomers could not be certain if the spectral absorption lines were from a companion object or from other stars along the line of sight to SN 1993J. "Until now, nobody was ever able to directly detect the glow of the star, called continuum emission," Fox said.

The companion star is so hot that the so-called continuum glow is largely in ultraviolet (UV) light, which can only be detected above Earth's absorbing atmosphere. "We were able to get that UV spectrum with Hubble. This conclusively shows that we have an excess of continuum emission in the UV, even after the light from other stars has been subtracted," said team member Azalee Bostroem of the Space Telescope Science Institute (STScI), in Baltimore, Maryland.

When a massive star reaches the end of its lifetime, it burns though all of its material and its iron core collapses. The rebounding outer material is seen as a supernova. But there are many different types of supernovae in the universe. Some supernovae are thought to have exploded from a single-star system. Other supernovae are thought to arise in a binary system consisting of a normal star with a white dwarf companion, or even two white dwarfs. The peculiar class of supernova called Type IIb combines the features of a supernova explosion in a binary system with what is seen when single massive stars explode.

SN 1993J, and all Type IIb supernovae, are unusual because they do not have a large amount of hydrogen present in the explosion. The key question has been: how did SN 1993J lose its hydrogen? In the model for a Type IIb supernova, the primary star loses most of its outer hydrogen envelope to the companion star prior to exploding, and the companion continues to burn as a super-hot helium star.

"When I first identified SN 1993J as a Type IIb supernova, I hoped that we would someday be able to detect its suspected companion star," said Filippenko. "The new Hubble data suggest that we have finally done so, confirming the leading model for Type IIb supernovae."
The team combined ground-based data for the optical light and images from two Hubble instruments to collect ultraviolet light. They then constructed a multi-wavelength spectrum that matched what was predicted for the glow of a companion star.

Fox, Filippenko, and Bostroem say that further research will include refining the constraints on this star and definitively showing that the star is present.

The results were published in the July 20 Astrophysical Journal.

For images and more information about Hubble, visit:

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. STScI conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

CONTACT
Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4514
Ori Fox
University of California, Berkeley, California
ofox@astro.berkeley.edu


Alex Filippenko
University of California, Berkeley, California
afilippenko@berkeley.edu

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How to Digitally Record/Video a UFO sighting:


Como registar digitalmente ou gravar um vídeo de um avistamento de um UFO:




Stabilize the camera on a tripod. If there is no tripod, then set it on top of a stable, flat surface. If that is not possible lean against a wall to stabilize your body and prevent the camera from filming in a shaky, unsteady manner.

Estabilize a camera com um tripé. Se não tiver um tripé, então coloque-a em cima de uma superfície estável. Se não for possível, então encoste-se a uma parede para estabilizar o corpo e evitar que a camera registe de maneira tremida e instável.

Provide visual reference points for comparison. This includes the horizon, treetops, lampposts, houses, and geographical landmarks (i.e., Horsetooth Reservoir, Mt. Adams, etc.) Provide this in the video whenever is appropriate and doesn’t detract from what your focus is, the UFO.

Forneça pontos visuais de referência para comparação. Isso inclui o horizonte, cimo das árvores, postes de iluminação, pontos de referência geográficos (como o Reservatório de Horsetooth, Mone Adams, etc) Forneça esses pontos no vídeo sempre que for apropriado e não se distraia do que é o seu foco, o UFO/a Nave.

Narrate your videotape. Provide details of the date, time, location, and direction (N,S,E,W) you are looking in. Provide your observations on the weather, including approximate temperature, windspeed, any visible cloud cover or noticeable weather anomalies or events. Narrate on the shape, size, color, movements, approximate altitude of the UFO, etc and what it appears to be doing. Also include any unusual physical, psychological or emotional sensations you might have. Narrate any visual reference points on camera so they correlate with what the viewer will see, and thereby will be better able to understand.

Faça a narração do vídeo. Forneça pormenores sobre a data, hora, local e direcção (Norte, Sul, Este, Oeste) que está a observar. Faça observações sobre as condições atmosféricas, incluindo a temperatura aproximada, velocidade do vento, quantidade de nuvens, anomalias ou acontecimentos meteorológicos evidentes. Descreva a forma, o tamanho, a cor, os movimentos, a altitude aproximada onde se encontra o UFO/nave, etc e o que aparenta estar a fazer. Inclua também quaisquer aspectos pouco habituais de sensações físicas, psicológicas ou emocionais que possa ter. Faça a narração de todos os pontos de referência visual que o espectador irá ver e que, deste modo, será capaz de compreender melhor.

Be persistent and consistent. Return to the scene to videotape and record at this same location. If you have been successful once, the UFO sightings may be occurring in this region regularly, perhaps for specific reasons unknown, and you may be successful again. You may also wish to return to the same location at a different time of day (daylight hours) for better orientation and reference. Film just a minute or two under “normal” circumstances for comparison. Write down what you remember immediately after. As soon as you are done recording the experience/event, immediately write down your impressions, memories, thoughts, emotions, etc. so it is on the record in writing. If there were other witnesses, have them independently record their own impressions, thoughts, etc. Include in this exercise any drawings, sketches, or diagrams. Make sure you date and sign your documentation.

Seja persistente e não contraditório. Volte ao local da cena e registe o mesmo local. Se foi bem sucedido uma vez, pode ser que nessa região ocorram avistamentos de UFOs/naves com regularidade, talvez por razões específicas desconhecidas, e talvez possa ser novamente bem sucedido. Pode também desejar voltar ao mesmo lugar a horas diferentes do dia (durante as horas de luz)para ter uma orientação e referência melhor. Filme apenas um ,inuto ou dois em circunstâncias “normais” para ter um termo de comparação. Escreva tudo o que viu imediatamente após o acontecimento. Logo após ter feito o registo da experiência/acontecimento, escreva imediatamente as impressões, memórias, pensamentos, emoções, etc para que fiquem registadas por escrito. Se houver outras testemunhas, peça-lhes para registar independentemente as suas próprias impressões, pensamentos, etc. Inclua quaisquer desenhos, esbolos, diagramas. Certifique-se que data e assina o seu documento/testemunho.

Always be prepared. Have a digital camera or better yet a video camera with you, charged and ready to go, at all times. Make sure you know how to use your camera (and your cell phone video/photo camera) quickly and properly. These events can occur suddenly, unexpectedly, and often quite randomly, so you will need to be prepared.

Esteja sempre preparado, Tenha sempre uma camera digital, melhor ainda, uma camera vídeo consigo, carregada e pronta a usar sempre que necessário. Certifique-se que sabe como lidar com a sua camera (ou com o seu celular/camera fotográfica) rápida e adequadamente. Esses acontecimentos podem acontecer súbita e inesperadamente e, por vezes, acidentalmente, por isso, necessita estar preparado.

Look up. Be prepared. Report. Share.

Olhe para cima, Esteja preparado, Relate, Partilhe.

MUFON.COM

ESOTERIC



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