Latest news with #MicrolensingObservationsinAstrophysics
Yahoo
25-04-2025
- Science
- Yahoo
First Utterly Alone Black Hole Confirmed Roaming The Cosmos
A lonely black hole roaming the cosmos in solitude has been confirmed for the first time. A closer look has revealed the dark object's identity, after much hubbub. The new analysis shows that the black hole has a mass of around 7.15 times that of the Sun, it's about 4,958 light-years away, and it's shooting through space at a speed of around 51 kilometers (32 miles) per second. But what's really special about it is that it's the only verified solitary black hole discovered wandering the Universe. Others of this class are usually found to have companions. In our galaxy, that's mostly stars, and it's the weird wobbles in those far-more-visible friends that give away the black hole's presence. Farther afield, pairs of black holes have also been detected through the gravitational waves they emit as they orbit each other and merge. Without a buddy, this black hole made itself known through a different mechanism, called gravitational microlensing. Essentially, its intense gravity warped the light from a background star, amplifying it and temporarily changing its apparent position in the sky. The calculated mass of the lens, as well as the lack of any emitted light of its own, indicates a black hole. The path to its identification wasn't as smooth as it sounds, however. The object first appeared in data in 2011, from two separate surveys searching for exactly this kind of event: the Optical Gravitational Lensing Experiment (OGLE) and Microlensing Observations in Astrophysics (MOA). The Hubble Space Telescope followed up with eight observations over six years, to determine how warped that starlight was. Photometry data was collected from 16 different telescopes and spectroscopy observations were taken at the peak of amplification. All together, this data pointed to a solo black hole of about 7.1 solar masses, located about 5,153 light-years away. But a second analysis conducted in 2022, using more Hubble data, came to a different conclusion. This team refined the mass estimate to between 1.6 and 4.4 solar masses. Since that's generally too small to be a black hole, they proposed a neutron star was a more likely candidate. However, a series of follow-up studies, including another from the neutron star team, lend more weight to the black hole explanation. Now, a new analysis, involving many of the scientists from the original study, unambiguously confirms that identity. It includes an extra three Hubble observations, extending the timeframe to 11 years, as well as updated OGLE data. "Our revised analysis, with the additional Hubble observations and updated photometry included, leads to results that have higher accuracy but are consistent with our previous measurements and our conclusion that the lens is a stellar-mass black hole," the team writes in a new paper. One of the biggest challenges in observing the lens is that the light from the background star is washed out by a very bright neighbor. The scientists had to very carefully subtract that light for each observation, as well as account for variations caused by different thermal environments in each Hubble orbit. The team also searched for any signs of a companion, and found that there's nothing bigger than 0.2 solar masses within at least 2,000 times the distance between Earth and the Sun. This may be the first black hole confirmed to be going solo, but it's far from the only one. The Universe should be teeming with these invisible rogues – it's just extremely rare that one would make itself known to us. The research was published in The Astrophysical Journal. Rare 'Smiley Face' Moon About to Hit The Sky With Venus And Saturn Hubble Celebrates 35 Years by Gifting Us 4 Breathtaking Cosmic Images A Magnetar's Birthplace Deepens The Mystery of Its Origins
Yahoo
17-02-2025
- Science
- Yahoo
NASA May Have Found The Fastest Planetary System We've Ever Seen
In the Milky Way's central bulge, about 24,000 light-years from Earth, a peculiar pair of objects appears to be hurtling through space at breakneck speed. Evidence suggests these objects are a high-velocity star and its accompanying exoplanet, a new study reports. If that's confirmed, it would set a new record as the fastest-moving exoplanet system known to science. Stars are on the move throughout the Milky Way, typically at a few hundred thousand miles per hour. Our Solar System's average velocity through the galaxy's Orion Arm is 450,000 miles per hour, or 200 kilometers per second. These two objects are careening twice as fast, at a speed of at least 1.2 million miles per hour (540 kilometers per second). "We think this is a so-called super-Neptune world orbiting a low-mass star at a distance that would lie between the orbits of Venus and Earth if it were in our solar system," says astronomer Sean Terry from the University of Maryland and NASA's Goddard Space Flight Center. "If so, it will be the first planet ever found orbiting a hypervelocity star." The two objects were initially found in 2011, as researchers hunted exoplanets in data from Microlensing Observations in Astrophysics (MOA), a project based at the University of Canterbury Mount John Observatory in New Zealand. Gravitational microlensing is a phenomenon that occurs when a massive celestial object is near the line of sight that runs between a distant observer on one side and a distant star on the other. Since mass warps spacetime, the star's light curves as it passes through the object's distorted spacetime on its way to the observer. If all three points align closely enough, the bent spacetime around the middle object acts as a lens for the observer, amplifying starlight. Researchers studying MOA data in 2011 determined the objects' relative mass – one is 2,300 times more massive than the other – but the actual mass of both remained unclear. "Determining the mass ratio is easy," says astronomer David Bennett from the University of Maryland and NASA Goddard, who worked on the 2011 and 2025 studies. "It's much more difficult to calculate their actual masses." Finding an object's actual mass requires knowing its distance, in a similar way to how moving a magnifying glass closer and farther distorts the apparent size of objects without altering the differences between them. Bennett and his colleagues in 2011 floated two scenarios for the pair of objects: Either it's a star and a planet, with the star slightly less massive than our sun and the planet 29 times more massive than Earth, or it's a less distant rogue super- Jupiter towing a moon smaller than Earth. For the new study, researchers sought to find out what these two are and what they're up to more than a decade later – using data from the Keck Observatory in Hawaii and the European Space Agency's Gaia satellite. They settled on a star system roughly 24,000 light-years away from Earth as the likeliest candidate. It's in the Milky Way's bright, densely populated central bulge of stars, the galactic downtown to our distant suburban perch. Based on its distance from the 2011 signal, the team calculated how fast the star is moving, finding its speed is more than twice that of our sun. That only accounts for its two-dimensional motion as seen from Earth, though. It could also be moving toward or away from us, which is harder to detect from our vantage, yet would mean it's moving even faster. That suggests this star might be fast enough to surpass the Milky Way's escape velocity, thought to be around 550 to 600 kilometers per second. If so, then it's headed for intergalactic space – although not for millions of years, since the Milky Way is huge and it's still pretty much right in the middle. While this solar system fits the profile of the 2011 objects, only time will tell. "To be certain the newly identified star is part of the system that caused the 2011 signal, we'd like to look again in another year and see if it moves the right amount and in the right direction," Bennett says. If the star just remains stationary, then we'll know it is not contributing to the signal-causing system. "That would mean the rogue planet and exomoon model is favored," explains astrophysicist Aparna Bhattacharya from the University of Maryland and NASA Goddard. The study was published in The Astronomical Journal. Astronomers Reveal Our Best Glimpse Yet of Planets Being Born A Supermassive Black Hole Is on a Collision Course With The Milky Way Astronomers Discover Nearby Alien World That May Sustain Life
