Archive for the ‘cosmology’ category: Page 13

Aug 13, 2020

Dying Breaths of a Massive Star – Supernovae That Result From Pulsating Supergiants Like Betelgeuse

Posted by in category: cosmology

Betelgeuse has been the center of significant media attention lately. The red supergiant is nearing the end of its life, and when a star over 10 times the mass of the Sun dies, it goes out in spectacular fashion. With its brightness recently dipping to the lowest point in the last hundred years, many space enthusiasts are excited that Betelgeuse may soon go supernova, exploding in a dazzling display that could be visible even in daylight.

While the famous star in Orion’s shoulder will likely meet its demise within the next million years — practically couple days in cosmic time — scientists maintain that its dimming is due to the star pulsating. The phenomenon is relatively common among red supergiants, and Betelgeuse has been known for decades to be in this group.

Coincidentally, researchers at UC Santa Barbara have already made predictions about the brightness of the supernova that would result when a pulsating star like Betelgeuse explodes.

Continue reading “Dying Breaths of a Massive Star – Supernovae That Result From Pulsating Supergiants Like Betelgeuse” »

Aug 13, 2020

Fastest-ever star discovered orbiting Milky Way’s supermassive black hole

Posted by in category: cosmology

S4714 can reach the unfathomable speed of nearly 15,000 miles per second.

Aug 11, 2020

Astronomers Think They’ve Found the Neutron Star Remnant From Supernova 1987a

Posted by in category: cosmology

In 1987, astronomers witnessed a spectacular event when they spotted a titanic supernova 168,000 light-years away in the Hydra constellation. Designated 1987A (since it was the first supernova detected that year), the explosion was one of the brightest supernova seen from Earth in more than 400 years. The last time was Kepler’s Supernova, which was visible to Earth-bound observers back in 1604 (hence the designation SN 1604).

Since then, astronomers have tried in vain to find the company object they believed to be at the heart of the nebula that resulted from the explosion. Thanks to recent observations and a follow-up study by two international teams of astronomers, new evidence has been provided that support the theory that there is a neutron star at the heart of SN 1604 – which would make it the youngest neutron star known to date.

The studies that describe their respective findings were both published in The Astrophysical Journal. The first, “High Angular Resolution ALMA Images of Dust and Molecules in the SN 1987A Ejecta,” appeared in the November 19th, 2019, issue while the second, “NS 1987A in SN 1987A,” was published in the July 30th, 2020 issue. Both studies represent the culmination of thirty years of research and waiting by astronomers.

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Aug 7, 2020

Hot ‘blob’ points to a neutron star lurking in Supernova 1987A

Posted by in category: cosmology

Astronomers have long suspected a city-sized neutron star hides within the dusty shroud of SN 1987A. And now, they’re closer than ever to proving their case.

But the extraordinary sight of a nearby supernova lingering in Earth’s night sky isn’t the only thing SN 1987A bestowed upon us. It also gave astronomers an unprecedented opportunity to investigate what triggers supernovae, as well as how such powerful blasts ripple through their surroundings. In fact, we can see the shockwave from SN 1987A still speeding outward today, interacting with clouds of dust that encircle the original site of the cosmic explosion.

Aug 5, 2020

Big Bounce Simulations Challenge the Big Bang

Posted by in categories: computing, cosmology

Detailed computer simulations have found that a cosmic contraction can generate features of the universe that we observe today.

Aug 4, 2020

Possible disappearance of a massive star in the low-metallicity galaxy PHL 293B

Posted by in category: cosmology

We investigate a suspected very massive star in one of the most metal-poor dwarf galaxies, PHL 293B. Excitingly, we find the sudden disappearance of the stellar signatures from our 2019 spectra, in particular the broad H lines with P Cygni profiles that have been associated with a massive luminous blue variable (LBV) star. Such features are absent from our spectra obtained in 2019 with the Echelle Spectrograph for Rocky Exoplanet- and Stable Spectroscopic Observation and X-shooter instruments of the European Southern Observatory’s Very Large Telescope. We compute radiative transfer models using cmfgen, which fit the observed spectrum of the LBV and are consistent with ground-based and archival Hubble Space Telescope photometry. Our models show that during 2001–2011, the LBV had a luminosity L* = 2.5–3.5 × 106 L, a mass-loss rate ˙ M = 0.005 − 0.020 M ⊙ yr−1, a wind velocity of 1000 km s−1, and effective and stellar temperatures of Teff = 6000–6800 and T* = 9500–15 000 K. These stellar properties indicate an eruptive state. We consider two main hypotheses for the absence of the broad emission components from the spectra obtained since 2011. One possibility is that we are seeing the end of an LBV eruption of a surviving star, with a mild drop in luminosity, a shift to hotter effective temperatures, and some dust obscuration. Alternatively, the LBV could have collapsed to a massive black hole without the production of a bright supernova.

Aug 4, 2020

A new test to investigate the origin of cosmic structure

Posted by in categories: cosmology, quantum physics

Many cosmologists believe that the universe’s structure is a result of quantum fluctuations that occurred during early expansion. Confirming this hypothesis, however, has proven highly challenging so far, as it is hard to discern between quantum and classical primordial fluctuations when analyzing existing cosmological data.

Two researchers at University of California and Deutsches Elektronen-Synchrotron DESY in Germany have recently devised a test based on the notion of primordial non-Gaussianity that could help to ascertain the origin of cosmic . In their paper, published in Physical Review Letters, they argue that detecting primordial non-Gaussanity could help to determine whether the patterns of the universe originated from quantum or classical fluctuations.

“One of the most beautiful ideas in all of science is that the structure we observed in the cosmos resulted from quantum fluctuations in the very that were then stretched by a rapid accelerated expansion,” Rafael Porto, one of the researchers who carried out the study, told “This ‘inflationary’ paradigm makes a lot of predictions which have been corroborated by data, yet the quantum nature of the primordial seed is extremely difficult to demonstrate directly.”

Aug 2, 2020

Quantum Physicists Crack Mystery of “Strange Metals” – A New State of Matter

Posted by in categories: cosmology, quantum physics

Strange metals have surprising connections to high-temperature superconductors and black holes.

Even by the standards of quantum physicists, strange metals are just plain odd. The materials are related to high-temperature superconductors and have surprising connections to the properties of black holes. Electrons in strange metals dissipate energy as fast as they’re allowed to under the laws of quantum mechanics, and the electrical resistivity of a strange metal, unlike that of ordinary metals, is proportional to the temperature.

Generating a theoretical understanding of strange metals is one of the biggest challenges in condensed matter physics. Now, using cutting-edge computational techniques, researchers from the Flatiron Institute in New York City and Cornell University have solved the first robust theoretical model of strange metals. The work reveals that strange metals are a new state of matter, the researchers report July 22 in the Proceedings of the National Academy of Sciences.

Continue reading “Quantum Physicists Crack Mystery of ‘Strange Metals’ – A New State of Matter” »

Aug 2, 2020

An Alternative to Dark Matter Passes Critical Test

Posted by in category: cosmology

Modified gravity theories have never been able to describe the universe’s first light. A new formulation does.

Aug 1, 2020

Did Scientists Actually Spot Evidence Of Another Universe?

Posted by in categories: cosmology, mathematics, physics

In a study published earlier this month, a team of theoretical physicists is claiming to have discovered the remnants of previous universes hidden within the leftover radiation from the Big Bang. Our universe is a vast collection of observable matter, like gas, dust, stars, etc., in addition to the ever-elusive dark matter and dark energy. In some sense, this universe is all we know, and even then, we can only directly study about 5% of it, leaving 95% a mystery that scientists are actively working to solve. However, this group of physicists is arguing that our universe isn’t alone; it’s just one in a long line of universes that are born, grow, and die. Among these scientists is mathematical physicist Roger Penrose, who worked closely with Stephen Hawking and currently is the Emeritus Rouse Ball Professor of Mathematics at Oxford University. Penrose and his collaborators follow a cosmological theory called conformal cyclic cosmology (CCC) in which universes, much like human beings, come into existence, expand, and then perish.

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