Latest news with #GerardvanBelle
Forbes
14-04-2025
- Science
- Forbes
Galaxy's Oldest Known Naked Eye Star Can Be Seen From A Dark Backyard
An illustration of one of the oldest stars ever found in our solar neighborhood. The aging star, ... More cataloged as HD140283, lies 190.1 light-years from Earth. The oldest known naked eye star in our Milky Way Galaxy is not some flashy red supergiant on the verge of going supernova, like Betelgeuse in the constellation of Orion. Nor is it part of an ancient globular cluster in the halo of our Milky Way. Instead, Mu Cassiopeia A is a simple field star --- a yellow dwarf of the same spectral type as our own sun, but one that clocks in at an astonishing 12.7 billion years old. It's part of a visual binary (double star) system known as Marfak, from the Arabic 'Al Marfiq' (the elbow), located in the Northern constellation of Cassiopeia. Located only some 25 light years away, Mu Cas A is headed towards us along our line of sight at a clip of some 97 km per second. In fact, by 5200 A.D., the star will have moved into the constellation of Perseus. Most of the stars in our galaxy aren't as old as Mu Cas A & B, Astronomer Gerard van Belle, director of science at Lowell Observatory in Flagstaff, Ariz., told me via email. This binary star tells us about what the earliest generation of stars were like from the birth of the Milky Way galaxy, which was expected to have happened only 800 million years after the Big Bang, he says. On any given clear night in the Northern Hemisphere, those who can find a dark enough spot can see it with the naked eye. And with a decent pair of binoculars, you are guaranteed success, even if you live in a suburban area with light pollution. Here's how to find Mu Cas A on the sky. From the giant W in Cassiopeia, follow the two outer arms of the 'W' to where (if extended below the W), those two arms would intersect, says van Belle. That's the location of Mu Cas A, he says. The star Mu Cas A is located in the center of the red dot if following an imaginary line down from ... More the outer arms of the crown of Cassiopeia in the Northern Hemisphere. The primary star, mu Cas A (sometimes noted as 'Aa') is a G5V main sequence star - like our sun, just a touch redder, says van Belle. For its color, it's cooler than expected, because it's old and therefore has low 'metal' content, he says. But unlike our sun, it has very little elements heavier than hydrogen or helium, says van Belle. Incredibly, Mu Cas was likely formed in a dwarf galaxy that became part of our Milky Way even before the disk of our own galaxy formed. Mu Cas and other stars like it in our galaxy are fascinating because they offer stellar theorists a view onto the earliest epochs of our galaxy. Mu Cas A lies in the general field of the Milky Way and might have belonged to a cluster at one time, but if so, the cluster has dissipated, Howard Bond, an astronomer at Penn State University and former at The Space Telescope Science Institute, told me via phone. The star probably belonged to a couple of small galaxies that collided together to make the Milky Way, says Bond. A couple of decades ago, stars like Mu Cas A were the source of controversy since for a while it seemed that our galaxy's oldest stars might be older than the cosmos itself. The so-called Methuselah star, known in scientific circles by its catalog number of HD140283 is a case in point. A well-known reference object in stellar evolution, its peculiar chemical composition, proximity and absence of reddening makes it an interesting case-study of so-called Population II stars (old metal-poor halo stars), note the authors of a 2024 paper appearing in the journal Astronomy & Astrophysics. Earlier estimates from observations dating back to the year 2000 placed the star at some 16 billion years old, says NASA. But new Hubble Space Telescope age estimates have reduced the range of measurement uncertainty, so that the star's age overlaps with the universe's age, says NASA. Lying some 190 light years away, HD140283's orbit carries it down through the plane of our galaxy from the ancient halo of stars that encircle the Milky Way, says NASA. The halo stars are among the first inhabitants of our galaxy and collectively represent an older population from the stars, like our sun, that formed later in the disk, NASA notes. HD140283 is still one of the oldest stars for which an age has been determined, says Bond. I would not claim it is the oldest known, but it still is one of the best ones for measuring an age, because it is so nearby and relatively bright, he says. Viewable with binoculars, the Methuselah star is now thought to have an age of some 12.3 billion years, at least a billion and a half years younger than the current age of our cosmos. Now at the end of its life, Mu Cas A is expected to remain on the main sequence as a hydrogen-burning star for roughly another billion years. When Mu Cas A does begin its red giant phase, it will have lived about a third longer than our own sun, which is expected to veer off the main sequence in another 6 billion years or so.
Yahoo
28-02-2025
- Science
- Yahoo
7-planet parade will be visible on last day of February
Attention, stargazers: Another celestial phenomenon is set to appear in the night sky Friday evening. Seven planets -- Mars, Jupiter, Uranus, Neptune, Mercury, Saturn and Venus -- will be visible simultaneously and look like they're all aligned when seen from Earth after sunset. An extraordinary event also known as planetary alignment or a planet parade, this February's seven-planet parade features one more celestial body than last month's six-planet alignment. "You have to do it right at sunset and you have to be able to see the eastern horizon very clearly because those three planets that are very close to the sun right now are pretty hard to catch," Dr. Gerard van Belle, an astronomer and the director of science at Lowell Observatory, told ABC News of the best time to watch the phenomenon. "Mercury is always hard to catch because it orbits so close to the sun. And Saturn, Neptune just happened to line up right there as well. And things like Neptune and Uranus, you'll need a telescope or binoculars to see, but other than that, Venus and Jupiter and Mars should all be really bright and easy to pick off just with your eyes." Parade of planets this month will feature celestial bodies in alignment According to NASA, multi-planet lineups are visible "every few years," but a seven-planet alignment is particularly uncommon, as each planet's orbit varies, with some moving more quickly and Mercury, in particular, being visible during its 88-day orbit for only "a couple of weeks at a time" each year. The solar system has eight planets overall – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Mercury is the closest planet to the sun and Earth is the third planet from the sun, while Neptune is the furthest. There are also five additional celestial bodies called dwarf planets, including Pluto, Ceres, Eris, Haumea and Makemake. Grad student discovers planet orbiting around nearby star, astronomers say The next chance to catch a planetary alignment after this month, according to NASA, will be in late August when a four-planet parade will be visible before sunrise. 7-planet parade will be visible on last day of February originally appeared on
New York Times
24-02-2025
- Science
- New York Times
A Parade of Planets Is Marching Through the Night Sky
Astute skywatchers may have already seen the striking line of planets across the night sky in January. This week Mercury joins the queue. Now every other world in our solar system will be visible among the stars at the same time — if you know where to look. According to Gerard van Belle, director of science at Lowell Observatory in Arizona, an alignment of seven planets is neither mystical nor particularly rare. 'On the scale of supermoon to death asteroid, this is more a supermoon sort of thing,' Dr. van Belle said. Still, the planetary parade, as the event is colloquially named, 'makes for a very nice excuse to go outside at night, maybe with a glass of wine, and enjoy the night sky.' A Parade of Planets Beginning in late February, seven planets will align in the night sky. But Uranus and Neptune may require a telescope to see. Mars SKY AT SUNSET ORION Jupiter Uranus Plane of Earth's orbit Venus Neptune Mercury Saturn HORIZON LOOKING WEST Saturn Line of sight to Neptune SOLAR SYSTEM Line of sight to Uranus Jupiter Viewed from above the solar system, the seven planets will fall within Earth's line of sight at sunset, and will not be obscured by the sun. Mercury Sun Mars Venus Earth SKY AT SUNSET Mars ORION Jupiter Uranus Plane of Earth's orbit Venus Neptune Mercury Saturn HORIZON LOOKING WEST Viewed from above the solar system, the seven planets will fall within Earth's line of sight at sunset, and will not be obscured by the sun. Saturn Line of sight to Neptune SOLAR SYSTEM Line of sight to Uranus Jupiter Mercury Sun Venus Earth Mars By Jonathan Corum | Source: NASA Why are the planets aligned? Whenever planets are visible in the night sky, they always appear roughly along the same line. This path, known as the ecliptic, is the same one that the sun travels along during the day. This happens because the planets orbit around the sun in the same plane. Dr. van Belle likened the configuration to a vinyl record: The sun is in the center, and the grooves are the orbits of the planets around it. Want all of The Times? Subscribe.
