• chevron_right

      Study: Conflicting values for Hubble constant not due to measurement error

      news.movim.eu / ArsTechnica · Monday, 11 March - 22:51 · 1 minute

    This image of NGC 5468, a galaxy located about 130 million light-years from Earth, combines data from the Hubble and James Webb space telescopes.

    Enlarge / This image of NGC 5468, about 130 million light-years from Earth, combines data from the Hubble and Webb space telescopes. (credit: NASA/ESA/CSA/STScI/A. Riess (JHU))

    Astronomers have made new measurements of the Hubble Constant , a measure of how quickly the Universe is expanding, by combining data from the Hubble Space Telescope and the James Webb Space Telescope. Their results confirmed the accuracy of Hubble's earlier measurement of the constant's value, according to their recent paper published in The Astrophysical Journal Letters, with implications for a long-standing discrepancy in values obtained by different observational methods known as the "Hubble tension."

    There was a time when scientists believed the Universe was static, but that changed with Albert Einstein's general theory of relativity. Alexander Friedmann published a set of equations showing that the Universe might actually be expanding in 1922, with Georges Lemaitre later making an independent derivation to arrive at that same conclusion. Edwin Hubble confirmed this expansion with observational data in 1929. Prior to this, Einstein had been trying to modify general relativity by adding a cosmological constant in order to get a static universe from his theory; after Hubble's discovery, legend has it , he referred to that effort as his biggest blunder.

    As previously reported , the Hubble constant is a measure of the universe's expansion expressed in units of kilometers per second per megaparsec. So, each second, every megaparsec of the Universe expands by a certain number of kilometers. Another way to think of this is in terms of a relatively stationary object a megaparsec away: Each second, it gets a number of kilometers more distant.

    Read 7 remaining paragraphs | Comments

    • chevron_right

      Half of the mass of an early galaxy is in its central black hole

      news.movim.eu / ArsTechnica · Monday, 6 November - 22:45 · 1 minute

    Image of a field of stars with a large purple glow in the center.

    Enlarge / Inset shows the JWST image of the galaxy in infrared, along with the X-rays from the black hole seen by the Chandra. While the X-ray source is far smaller than the galaxy, X-rays are much harder to remove. (credit: X-ray: NASA/CXC/SAO/Ákos Bogdán; Infrared: NASA/ESA/CSA/STScI; Image Processing: NASA/CXC/SAO/L. Frattare & K. Arcand )

    Researchers combing through some of the earliest galaxies in the Universe have found one that appears to have an actively feeding central black hole. Based on the amount of radiation it's emitting, the researchers estimate that it accounts for roughly half of the mass of the entire galaxy it's in—an astonishingly high fraction compared to modern galaxies.

    The fact that such a large object can exist only half a billion years after the Big Bang places severe limits on how it could possibly have formed, strongly suggesting that supermassive black holes formed without ever having gone through an intermediate step involving a star.

    Old X-rays

    The earliest galaxies in the Universe that we know about have been identified using the James Webb Space Telescope, which took advantage of a galaxy cluster in the foreground that magnified more distant ones through gravitational lensing. Using the lens provided by a specific cluster, the Webb identified 11 galaxies that were imaged as they existed less than a billion years after the Big Bang.

    Read 15 remaining paragraphs | Comments

    • chevron_right

      Webb Telescope confirms nearby rocky planet has no atmosphere

      news.movim.eu / ArsTechnica · Monday, 27 March, 2023 - 19:10 · 1 minute

    Image of a grey planet orbiting a dim red star.

    Enlarge / An illustration of what the inner portion of the TRAPPIST-1 system might look like. (credit: NASA, ESA, CSA, J. Olmsted (STScI), T. P. Greene (NASA Ames), T. Bell (BAERI), E. Ducrot (CEA), P. Lagage (CEA) )

    At this point, we've discovered lots of exoplanets that fall under the general label "Earth-like." They're rocky, and many orbit at distances from their host stars to potentially have moderate temperatures. But "like" is doing a lot of work there. In many cases, we have no idea whether they even have an atmosphere, and the greenhouse effect means that the atmosphere can have a huge impact on the planet's temperature. So the Earth-like category can include dry, baking hellscapes like Venus with its massive atmosphere, as well as dry, frozen hellscapes with sparse atmospheres like Mars.

    But we're slowly getting the chance to image the atmospheres of rocky exoplanets. And today, researchers are releasing the results of turning the Webb Space Telescope on a rocky planet orbiting a nearby star, showing that the new hardware is so sensitive that it can detect the star blocking out light originating from the planet. The results suggest that the planet has very little atmosphere and is mostly radiating away heat from being baked by its nearby star.

    The ultra-cool dwarf and its seven planets

    TRAPPIST-1 is a small, reddish star—in astronomical terminology, it's an "ultra-cool dwarf"—that's about 40 light-years from Earth. While the star itself is pretty nondescript, it's notable for having lots of planets, with seven in total having been identified so far. All of these are small, rocky bodies, much like the ones that occupy the inner portion of our Solar System. While the star itself emits very little light, the planets are all packed in closer to it than Mercury is to the Sun.

    Read 14 remaining paragraphs | Comments

    • chevron_right

      Universe’s first galaxies unexpectedly large

      news.movim.eu / ArsTechnica · Wednesday, 22 February, 2023 - 20:24 · 1 minute

    Image of distant galaxies, partly distorted by gravitational lensing.

    Enlarge (credit: NASA, ESA, CSA, and STScI )

    How soon after the Big Bang could stars and galaxies start to form? It has been a difficult question to answer, as much of the light from the first stars has been shifted deep into the infrared during the billions of years it has spent traveling to Earth. One of the design goals of the Webb Telescope was to create a telescope that could pick up this light and tell us something about the early history of the Universe. And initial data has been very promising, with astronomers seemingly racing each other to find the most distant galaxy yet observed .

    Now, a new study looks into the properties of a set of distant galaxies, showing that one of them appears to be larger than the Milky Way at only 700 million years after the Big Bang. If the results hold up, then the number of galaxies of this size may be difficult to reconcile with the forces we think built the Universe.

    Going deep

    The technique for spotting early galaxies is fairly simple. The earliest stars and galaxies were embedded in a Universe filled with hydrogen atoms, which can be ionized if they absorb light at specific wavelengths in the UV range. This absorption creates a distinctive feature in the light arriving from distant galaxies. Over the billions of years it takes to reach us, however, that feature has been red shifted by the expansion of the Universe so that now it appears deep in the infrared portion of the spectrum. If you can identify where it resides, then you can determine just how far away the galaxy is.

    Read 8 remaining paragraphs | Comments

    • chevron_right

      Where 2022’s news was (mostly) good: Yhe year’s top science stories

      news.movim.eu / ArsTechnica · Saturday, 31 December, 2022 - 11:06 · 1 minute

    The self-portrait of Webb's mirrors is also looking very sharp thanks to the improved alignment.

    Enlarge / The self-portrait of Webb's mirrors is also looking very sharp thanks to the improved alignment. (credit: NASA/STScI )

    How often does something work exactly as planned, and live up to its hype? In most of the world, that's the equivalent of stumbling across a unicorn that's holding a few winning lottery tickets in its teeth. But that pretty much describes our top science story of 2022, the successful deployment and initial images from the Webb Telescope.

    In fact, there was lots of good news to come out of the world of science, with a steady flow of fascinating discoveries and tantalizing potential tech—over 200 individual articles drew in 100,000 readers or more, and the topics they covered came from all areas of science. Of course, with a pandemic and climate change happening, not everything we wrote was good news. But as the top stories of the year indicate, our readers found interest in a remarkable range of topics.

    10. Fauci on the rebound

    For better and worse, Anthony Fauci has become the public face of the pandemic response in the US. He's trusted by some for his personable, plain-spoken advice regarding how to manage the risks of infection—and vilified by others for his advocacy of vaccinations (plus a handful of conspiracy theories). So, when Fauci himself ended up on the wrong end of risk management and got a SARS-CoV-2 infection, that was news as well, and our pandemic specialist, Beth Mole, was there for it.

    Read 25 remaining paragraphs | Comments

    • chevron_right

      Webb captures truly strange set of rings built by massive stars

      news.movim.eu / ArsTechnica · Wednesday, 12 October, 2022 - 17:04

    Image of a bright area partially surrounded by rings.

    Enlarge (credit: Image courtesy of University of Sydney)

    Today, Nature Astronomy released a paper that shows off the sorts of science the Webb Telescope was designed to produce. Early on, the new telescope was pointed at a system of two massive stars that orbit each other closely. Ground-based observations had detected a ring or two produced by the interactions of these giants; the Webb was able to determine that there are at least 17 concentric rings of material that have been put in place over the previous 130 years.

    And just to show off, astronomers were able to obtain a spectrum of the material that forms the rings.

    It's difficult to express just how bizarre these rings look (just check out the image yourself at the top of this article!). Yet modeling the forces that are thought to have put them in place produces a near-exact replica of the structures.

    Read 11 remaining paragraphs | Comments

    • chevron_right

      New JWST image reveals full glory of Neptune, its moons, and rings

      news.movim.eu / ArsTechnica · Wednesday, 21 September, 2022 - 13:18

    Webb captured seven of Neptune’s 14 known moons: Galatea, Naiad, Thalassa, Despina, Proteus, Larissa, and Triton. Neptune’s large and unusual moon, Triton, dominates this Webb portrait of Neptune as a very bright point of light sporting diffraction spikes.

    Enlarge / Webb captured seven of Neptune’s 14 known moons: Galatea, Naiad, Thalassa, Despina, Proteus, Larissa, and Triton. Neptune’s large and unusual moon, Triton, dominates this Webb portrait of Neptune as a very bright point of light sporting diffraction spikes. (credit: NASA, ESA, CSA, STScI)

    Scientists are wasting no time in pointing the powerful new James Webb Space Telescope all over the Universe, as well as into our own backyard. Recently, astronomers took data on the eighth planet from the Sun in our Solar System, Neptune. NASA released the first images of this world on Wednesday.

    The third-largest planet in our Solar System, Neptune often appears bright blue in images due to the presence of gaseous methane. The Webb telescope, however, observes light in the infrared portion of the spectrum, so its "Near-Infrared Camera" photos show a ghostly white planet. This is because the methane in Neptune's atmosphere absorbs reddish and infrared light.

    In the new view of Neptune, the exception to this is the planet's high-altitude methane ice clouds, which reflect sunlight before it can be absorbed by the methane. These appear as brilliant, bright features, NASA says.

    Read 4 remaining paragraphs | Comments

    • chevron_right

      Putting together the Webb telescope’s mid-infrared eyes

      news.movim.eu / ArsTechnica · Wednesday, 10 August, 2022 - 16:56

    Image of an oval-shaped galaxy.

    Enlarge / The dust in this galaxy, shaded red, required the MIRI instrument to resolve. (credit: NASA, ESA, CSA, STScI )

    There is more than one reason why the Mid-Infrared Instrument (MIRI) on board the James Webb Space Telescope (JWST) is considered to be pioneering. Of the four instruments on JWST, it's the only one that observes in the mid-infrared range, from 5 to 28 microns; the other three are near-infrared devices with a wavelength range of 0.6 to 5 microns. To reach these wavelengths, MIRI had to be kept the coldest of any instrument on JWST, meaning it essentially set the requirements for the telescope’s cooling system.

    The stunning images taken by MIRI are a testimony to the remarkable engineering feats that went into it, feats that were achieved by overcoming formidable challenges through meticulous transatlantic teamwork and coordination.

    Making MIRI

    “I remember being told in the early days that the instrument will never be built. Some people at NASA looked at the block diagram of our management structure and said it will never work,” Professor George Rieke, who leads the science team of MIRI, recalled.

    Read 19 remaining paragraphs | Comments

    • chevron_right

      One week later, astronomers find a galaxy even deeper back in time

      news.movim.eu / ArsTechnica · Tuesday, 26 July, 2022 - 21:28 · 1 minute

    The James Webb Space Telescope continues to deliver on its promises on discovering early galaxies.

    Enlarge / The James Webb Space Telescope continues to deliver on its promises on discovering early galaxies. (credit: NASA)

    Data from the Webb Space Telescope has only gotten into the hands of astronomers over the last few weeks, but they've been waiting for years for this, and apparently had analyses set to go. The result has been something like a race back in time, as new discoveries find objects that formed ever closer to the Big Bang that produced our Universe. Last week, one of these searches turned up a galaxy that was present less than 400 million years after the Big Bang. This week, a new analysis has picked out a galaxy as it appeared only 233 million years after the Universe popped into existence.

    The discovery is a happy byproduct of work that was designed to answer a more general question: How many galaxies should we expect to see at different time points after the Big Bang?

    Back in time

    As we mentioned last week, the early Universe was opaque to light at any wavelengths that carry more energy than is needed to ionize hydrogen. That energy is in the UV portion of the spectrum, but the red shift caused by 13 billion years of an expanding Universe has shifted that cutoff point into the infrared portion of the spectrum. To find galaxies from this time, we have to look for objects that aren't visible at shorter infrared wavelengths (meaning that light was once above the hydrogen cutoff), but do appear at lower-energy wavelengths.

    Read 10 remaining paragraphs | Comments