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What Might Be Speeding Up the Universe’s Expansion? The discrepancy between how fast the universe seems to be expanding and how fast we expect it to expand is one of cosmology’s most stubbornly persistent anomalies. Cosmologists base their...

What Might Be Speeding Up the Universe’s Expansion?

The discrepancy between how fast the universe seems to be expanding and how fast we expect it to expand is one of cosmology’s most stubbornly persistent anomalies.

Cosmologists base their expectation of the expansion rate — a rate known as the Hubble constant — on measurements of radiation emitted shortly after the Big Bang. This radiation reveals the precise ingredients of the early universe. Cosmologists plug the ingredients into their model of cosmic evolution and run the model forward to see how quickly space should be expanding today.

Yet the prediction falls short: When cosmologists observe astronomical objects such as pulsating stars and exploding supernovas, they see a universe that’s expanding faster, with a larger Hubble constant.

The discrepancy, known as the Hubble tension, has persisted even as all the measurements have grown more precise. Some astrophysicists continue to debate whether the tension might be nothing more than a measurement error. But if the discrepancy is real, it means something is missing from cosmologists’ model of the universe.

Source: quantamagazine.org
cosmology physics astrophysics astronomy
Do We Live in a Lopsided Universe? According to the key tenets of modern physics, the cosmos is “isotropic” at multi-billion-light-year scales—meaning it should have the same look and behavior in every direction. Ever since the big bang nearly 14...

Do We Live in a Lopsided Universe?

According to the key tenets of modern physics, the cosmos is “isotropic” at multi-billion-light-year scales—meaning it should have the same look and behavior in every direction. Ever since the big bang nearly 14 billion years ago, the universe ought to have expanded identically everywhere. And that expectation matches what astronomers see when they observe the smooth uniformity of the big bang’s all-sky afterglow: the cosmic microwave background (CMB). Now, however, an x-ray survey of distances to galaxy clusters across the heavens suggests some are significantly closer or farther away than isotropy would predict. This finding could be a sign that the universe is actually “anisotropic”—expanding faster in some regions than it does in others. With apologies to anyone seeking a cosmic excuse for personal woes, maybe the universe is not so directionless after all.

This possible evidence for anisotropy comes from an international team led by astronomer Konstantinos Migkas of the University of Bonn in Germany. And it relies on new or archival data on nearly 850 galaxy clusters seen by NASA’s Chandra X-ray Observatory, the European Space Agency’s XMM-Newton satellite and Japan’s Advanced Satellite for Cosmology and Astrophysics.

Source: scientificamerican.com
astronomy space cosmology
Exoplanet Apparently Disappears in Latest Hubble Observations What astronomers thought was a planet beyond our solar system has now seemingly vanished from sight. Though this happens in science fiction, such as Superman’s home planet Krypton...

Exoplanet Apparently Disappears in Latest Hubble Observations

What astronomers thought was a planet beyond our solar system has now seemingly vanished from sight. Though this happens in science fiction, such as Superman’s home planet Krypton exploding, astronomers are looking for a plausible explanation.

One interpretation is that, rather than being a full-sized planetary object, which was first photographed in 2004, it could instead be a vast, expanding cloud of dust produced in a collision between two large bodies orbiting the bright nearby star Fomalhaut. Potential follow-up observations might confirm this extraordinary conclusion.

“These collisions are exceedingly rare and so this is a big deal that we actually get to see one,” said András Gáspár of the University of Arizona, Tucson. “We believe that we were at the right place at the right time to have witnessed such an unlikely event with NASA’s Hubble Space Telescope.”

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Source: nasa.gov
space astronomy hubble space telescope exoplanet
Interstellar Comet Borisov Reveals Its Chemistry and Possible Origins On Aug. 30, 2019, when amateur astronomer Gennady Borisov gazed upward with his homemade telescope, he spotted an object moving in an unusual direction. Now called 2I/Borisov, this...

Interstellar Comet Borisov Reveals Its Chemistry and Possible Origins

On Aug. 30, 2019, when amateur astronomer Gennady Borisov gazed upward with his homemade telescope, he spotted an object moving in an unusual direction. Now called 2I/Borisov, this runaway point of light turned out to be the first confirmed comet to enter our solar system from some unknown place beyond our Sun’s influence. Astronomers everywhere rushed to take a look with some of the most powerful instruments in the world, hoping to learn as much as they could about the mysterious visitor.

Now, thanks to observations with NASA’s Hubble Space Telescope and the National Radio Astronomy Observatory’s Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have figured out that 2I/Borisov has an unusual composition. Specifically, it has a higher concentration of carbon monoxide than any comet seen at a similar distance; that is, within about 200 million miles (300 million kilometers) of the Sun.

This suggests to scientists that the comet could have formed around a red dwarf — a smaller, fainter type of star than the Sun — though other kinds of stars are possible. Another idea is that 2I/Borisov could be a carbon monoxide-rich fragment of a small planet.

Source: nasa.gov
comet borisov astronomy space chemistry hubble space telescope nasa
The New Horizons Parallax Program Since its launch in January 2006, NASA’s New Horizons spacecraft has flown past Jupiter in 2007, Pluto in 2015, and most recently, the Kuiper Belt object Arrokoth in 2019. Speeding through the Kuiper Belt at some...

The New Horizons Parallax Program

Since its launch in January 2006, NASA’s New Horizons spacecraft has flown past Jupiter in 2007, Pluto in 2015, and most recently, the Kuiper Belt object Arrokoth in 2019. Speeding through the Kuiper Belt at some 31,000 miles (50,000 kilometers) per hour, it’s on a fast path out of the solar system and toward the Milky Way galaxy.

This spring, New Horizons will be more than 46 times farther from the Sun than the Earth, having traveled more than 5 billion miles (8 billion kilometers) since launch. At this great distance, from New Horizons’ view, the nearest stars will appear to have shifted in position relative to more distant stars, compared to where we see them from Earth. On April 22 and 23, 2020, New Horizons will gather images of two of the nearest stars, Proxima Centauri and Wolf 359, to demonstrate this effect.

Source: pluto.jhuapl.edu
astronomy nasa space new horizons
Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole The star S2 orbiting the compact radio source Sgr A* is a precision probe of the gravitational field around the closest massive black...

Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole

The star S2 orbiting the compact radio source Sgr A* is a precision probe of the gravitational field around the closest massive black hole (candidate). Over the last 2.7 decades we have monitored the star’s radial velocity and motion on the sky, mainly with the SINFONI and NACO adaptive optics(AO) instruments on the ESO VLT, and since 2017, with the four-telescope interferometric beam combiner instrument GRAVITY. In this paper we  report  the  first  detection  of  the  General  Relativity  (GR)  Schwarzschild  Precession  (SP)  in  S2’s  orbit.  Owing  to  its  highly  elliptical  orbit(e=0.88), S2’s SP is mainly a kink between the pre-and post-pericentre directions of motion≈±1 year around pericentre passage, relative to the corresponding Kepler orbit. The superb 2017-2019 astrometry of GRAVITY defines the pericentre passage and outgoing direction. The incoming direction is anchored by 118 NACO-AO measurements of S2’s position in the infrared reference frame, with an additional 75 direct measurements of the S2-Sgr A* separation during bright states (‘flares’) of Sgr A*. Our 14-parameter model fits for the distance, central mass, the position andmotion of the reference frame of the AO astrometry relative to the mass, the six parameters of the orbit, as well as a dimensionless parameter fSP for the SP (fSP=0 for Newton and 1 for GR). From data up to the end of 2019 we robustly detect the SP of S2,δφ≈12′per orbital period.From posterior fitting and MCMC Bayesian analysis with different weighting schemes and bootstrapping we find fSP=1.10±0.19. The S2 data are fully consistent with GR. Any extended mass inside S2’s orbit cannot exceed≈0.1% of the central mass. Any compact third mass inside the central arc-second must be less than about 1000M.

Source: eso.org
astronomy physics
Earth-Size, Habitable Zone Planet Found Hidden in Early NASA Kepler Data A team of transatlantic scientists, using reanalyzed data from NASA’s Kepler space telescope, has discovered an Earth-size exoplanet orbiting in its star’s habitable zone, the...

Earth-Size, Habitable Zone Planet Found Hidden in Early NASA Kepler Data

A team of transatlantic scientists, using reanalyzed data from NASA’s Kepler space telescope, has discovered an Earth-size exoplanet orbiting in its star’s habitable zone, the area around a star where a rocky planet could support liquid water.

Scientists discovered this planet, called Kepler-1649c, when looking through old observations from Kepler, which the agency retired in 2018. While previous searches with a computer algorithm misidentified it, researchers reviewing Kepler data took a second look at the signature and recognized it as a planet. Out of all the exoplanets found by Kepler, this distant world – located 300 light-years from Earth – is most similar to Earth in size and estimated temperature.

Source: nasa.gov
exoplanet space astronomy nasa kepler
New formation theory explains the mysterious interstellar object ‘Oumuamua First author Yun Zhang at the National Astronomical Observatories of the Chinese Academy of Sciences and coauthor Douglas N. C. Lin at UC Santa Cruz, used computer simulations...

New formation theory explains the mysterious interstellar object ‘Oumuamua

First author Yun Zhang at the National Astronomical Observatories of the Chinese Academy of Sciences and coauthor Douglas N. C. Lin at UC Santa Cruz, used computer simulations to show how objects like ‘Oumuamua can form under the influence of tidal forces like those felt by Earth’s oceans. Their formation theory explains all of ‘Oumuamua’s unusual characteristics.

“We showed that ‘Oumuamua-like interstellar objects can be produced through extensive tidal fragmentation during close encounters of their parent bodies with their host stars, and then ejected into interstellar space,” said Lin, professor emeritus of astronomy and astrophysics at UC Santa Cruz.

Source: news.ucsc.edu
'oumuamua space astronomy
Something is Lurking in the Heart of Quasar 3C 279 One year ago, the Event Horizon Telescope (EHT) Collaboration published the first image of a black hole in the nearby radio galaxy M 87. Now the collaboration has extracted new information from the...

Something is Lurking in the Heart of Quasar 3C 279

One year ago, the Event Horizon Telescope (EHT) Collaboration published the first image of a black hole in the nearby radio galaxy M 87. Now the collaboration has extracted new information from the EHT data on the distant quasar 3C 279: they observed the finest detail ever seen in a jet produced by a supermassive black hole. New analyses, led by Jae-Young Kim from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, enabled the collaboration to trace the jet back to its launch point, close to where violently variable radiation from across the electromagnetic spectrum arises.

Source: eventhorizontelescope.org
astronomy black hole space event horizon telescope
Hubble Finds Best Evidence for Elusive Mid-Size Black Hole Intermediate-mass black holes (IMBHs) are a long-sought “missing link” in black hole evolution. There have been a few other IMBH candidates found to date. They are smaller than the...

Hubble Finds Best Evidence for Elusive Mid-Size Black Hole

Intermediate-mass black holes (IMBHs) are a long-sought “missing link” in black hole evolution. There have been a few other IMBH candidates found to date. They are smaller than the supermassive black holes that lie at the cores of large galaxies, but larger than stellar-mass black holes formed by the collapse of massive stars. This new black hole is over 50 000 times the mass of our Sun.

IMBHs are hard to find. “Intermediate-mass black holes are very elusive objects, and so it is critical to carefully consider and rule out alternative explanations for each candidate. That is what Hubble has allowed us to do for our candidate,” said Dacheng Lin of the University of New Hampshire, principal investigator of the study.

Source: spacetelescope.org
astronomy space black hole hubble space telescope
Possible fragmentation of interstellar comet 2I/Borisov Images obtained by HST/WFC3 GO programs 16041 (PI Jewitt; ATEL #13611) and 16040 (PI Bolin) on 2020 March 23 and 28 indicate the presence of a small fragment separated by ~0.3 arcsec in the...

Possible fragmentation of interstellar comet 2I/Borisov

Images obtained by HST/WFC3 GO programs 16041 (PI Jewitt; ATEL #13611) and 16040 (PI Bolin) on 2020 March 23 and 28 indicate the presence of a small fragment separated by ~0.3 arcsec in the anti-solar direction, west of north, from the coma’s optocenter in addition to the bimodal appearance described by Jewitt et al. ATEL #13611. The distance between the optocenter and the fragment changes by 1-2 pixels (0.0395 arcsec/pixel) between the 2020 March 23 and 2020 March 28 observation dates. This implies a lower limit on the relative velocity between the nucleus and the fragment due to projection effects of at least ~0.5 m/s, consistent with the escape velocity from a sub km-scale radius body. The angular separation and motion detected in the 2020 March 23 and 28 data are consistent with a release date in 2020 March 7 around the time of the comet’s ~0.7 mag outburst observed by ground-based facilities (Drahus et al. ATel #13549., Jehin et al. 2020, CBET 4729). The fragment is not seen in the most recent HST/WFC3 data taken on 2020 February 24 (GO 16041, PI Jewitt) which were acquired before the comet’s outburst. The fragment has an estimated upper size limit of <100 m, assuming a geometric albedo of 0.04, and is confirmed in HST/WFC3 2020 March 30 data taken by HST GO 16087, PI Jewitt. In addition, the post-outburst HST/WFC3 images show the existence of two new jets with position angles of 240 and 310 degrees not observed in previous HST/WFC3 images (Bolin 2020, arxiv:1912.07386).

Source: astronomerstelegram.org
space astronomy comet 2i/borisov
To Make the Perfect Mirror, Physicists Confront the Mystery of Glass The Laser Interferometer Gravitational-Wave Observatory can sense movements thousands of times tinier than the width of an atom partly because of the instrument’s near-perfect...

To Make the Perfect Mirror, Physicists Confront the Mystery of Glass

The Laser Interferometer Gravitational-Wave Observatory can sense movements thousands of times tinier than the width of an atom partly because of the instrument’s near-perfect mirrors. The mirrors bounce laser beams back and forth down the arms of LIGO’s L-shaped detectors. Changes in the relative lengths of the arms reveal when a gravitational wave flutters past Earth, stretching and squeezing space-time.They’re nothing like regular mirrors. In your bathroom mirror, light reflects off metal, which has glass in front of it merely for protection. But LIGO’s 100-kilowatt laser would fry any metal. Instead, its mirrors are made entirely of glass.

Source: quantamagazine.org
physics gravitational astronomy astronomy
Scientists Trace Neutron Star Crash That Helped Form Our Solar System Astronomers are on the hunt for the remnants of the neutron-star collision that gave Earth its precious metals. When neutron stars merge, they spew a wealth of short-lived elements...

Scientists Trace Neutron Star Crash That Helped Form Our Solar System

Astronomers are on the hunt for the remnants of the neutron-star collision that gave Earth its precious metals.

When neutron stars merge, they spew a wealth of short-lived elements into their surroundings, and these materials become part of later-forming solar systems. Now scientists are trying to close in on the merger that seeded our solar system by tracing the elements produced by the original decaying material. From that work, they believe the responsible merger occurred 100 million years before and 1,000 light-years away from the birth of our solar system.

“It was close,” the project’s lead scientist, Szabolcs Marka, who is a physicist at Columbia University, told Space.com. “If you look up at the sky and you see a neutron-star merger 1,000 light-years away, it would outshine the entire night sky.”

Marka and his colleague Imre Bartos, an astrophysicist at the University of Florida, used meteorites from the dawn of the solar system to track down the collision. They analyzed the isotopes—flavors of elements with different numbers of neutrons in their atoms—in these rocks.

Source: scientificamerican.com
astronomy space