https://observador.pt/2018/12/22/investigadores-chilenos-inventam-novo-metodo-de-ver-galaxias/
Citando:
"O estudo foi publicado na sexta-feira na revista científica The Astrophysical Journal e através da investigação descobriram-se enxames numa base de dados com 200.000 galáxias, usando apenas um método geométrico."
https://www.theguardian.com/science/2018/mar/28/galaxy-without-any-dark-matter-baffles-astronomers
Citando:
"Van Dokkum and colleagues identified the galaxy, NGC 1052-DF2, using a low-budget setup called the Dragonfly Telephoto Array in New Mexico, which they designed from 48 commercial cameras and paparazzi-style lenses.
The initial images just showed a ghostly blob on the night sky, but by peering more closely at it using the Gemini Multi Object Spectrograph and Keck telescopes they were able to pick out star clusters within the galaxy and track their movements. The team are now turning to look at other ultra-diffuse galaxies to see whether any others are similarly deficient in dark matter."
... e o enxame de Coma:
https://zap.aeiou.pt/hubble-encontra-milhares-aglomerados-estelares-orfaos-229817
Citando:
"O levantamento, publicado na edição de 9 de novembro da revista The Astrophysical Journal, permitirá aos astrónomos usar o campo de enxames globulares para mapear a distribuição de matéria e matéria escura no enxame galáctico de Coma, que contém mais de 1000 galáxias.
Dado que os enxames globulares são muito mais pequenos que galáxias inteiras – e muito mais abundantes – são um muito melhor indício de como a estrutura do espaço é distorcida pela gravidade do enxame de Coma.
De facto, o enxame de Coma é um dos primeiros lugares onde as anomalias gravitacionais observadas foram consideradas indicativas de uma grande quantidade de massa invisível no Universo – que depois seria chamada de “matéria escura”."
http://visao.sapo.pt/actualidade/sociedade/2018-11-09-Cientistas-cada-vez-mais-perto-de-confirmar-que-no-centro-da-nossa-galaxia-ha-um-buraco-negro-supermassivo
Citando:
"ada 16 anos, a estrela conhecida como S2, da constelação de Sagitário, passa a "rasar" por um objeto misterioso, bem no centro da nossa galáxia, a 26 mil anos luz da Terra, e que pesa qualquer coisa como 4 milhões de sóis. Mas este ano ofereceu uma oportunidade única às equipas de astrónomos que tentam provar a sua existência: durante vários meses, a "pequena" estrela fez a sua maior aproximação ao centro da galáxia, permitindo-lhes analisar melhor o comportamento da gravidade em ambientes extremos e colher pistas significativas sobre esse mega objeto."
https://www.independent.co.uk/news/science/galactic-wind-stars-galaxies-big-bang-milky-way-alma-a8525806.html
Citando:
"ALMA was able to pin down the effect in the galaxy known as SPT2319-55 using gravitational lensing, the process by which gravity bends light and in doing so magnifies events that would otherwise be impossible to observe using existing technology.
This technique has previously allowed scientists to identify planets far beyond the Milky Way for the first time."
https://gizmodo.com/the-universes-oldest-galaxies-could-be-right-in-the-mil-1828390203
Citando:
"Atoms started forming from protons and electrons a few hundred thousand years after the Big Bang. The resulting gas cooled, creating stars, but the stars didn’t last long. They exploded in huge supernovae, sending energy out into space. This split the atoms back up once again, “re-ionizing” them. It’s unclear when the first stars started to form or when re-ionization started, but they’re important periods in the Universe’s history, because they set the ball rolling to create the galaxies we see today."
The most widely accepted model says that galaxies are actually visible gas and dust coalescing inside larger haloes of a yet-to-be explained kind of mass called dark matter. Galaxies began forming with the first stars, but during the re-ionization period, astronomers think that temperatures rose too high, halting further galactic growth. Only at some later period, when large-enough dark matter halos coalesced, would the galaxy formation process pick up again."
https://phys.org/news/2018-08-massive-region-space-astronomers-galaxies.html
Citando:
"Astronomers have known that more than 12 billion years ago, about 1 billion years after the Big Bang, the gas in deep space was, on average, much more opaque than it is now in some regions, although the opacity varied widely from place to place. But they weren't sure about what caused those variations.
To learn why the differences occurred, the astronomers used one of the world's largest telescopes, the Subaru telescope on Mauna Kea in Hawaii, to search for galaxies of young stars in an exceptionally large region of space—500 million light-years across—where they knew the intergalactic gas was extremely opaque.
If the region had an unusually small number of galaxies, the scientists would be able to conclude that starlight could not penetrate as far as expected through the intergalactic gas; if it had an unusually large number of galaxies, the implication would be that the region had cooled significantly over the previous several hundred million years. (Having few galaxies in a region would mean not only that there was less light created by those galaxies, but also that even more opaque gas was being formed, so the light could not travel as far as astronomers had expected.)
"It was a rare case in astronomy where two competing models, both of which were compelling in their own way, offered precisely opposite predictions, and we were lucky that those predictions were testable," said Steven Furlanetto, a UCLA professor of astronomy and a co-author of the research.
The researchers found that region contains far fewer galaxies than expected—clear evidence that starlight could not get through. The paucity of galaxies could be the reason this region is so opaque.
"It is not that the opacity is a cause of the lack of galaxies," Furlanetto said. "Instead, it's the other way around."
They concluded that because the gas in deep space is kept transparent by ultraviolet lightfrom galaxies, fewer nearby galaxies might make it murkier."
