Connect with us

Science

Astronomers investigate disappearance of massive star

Published

on

June 30 (UPI) — An unstable massive star in the Kinman Dwarf galaxy, located 75 million light-years away, has disappeared, but scientists aren’t sure why or how.

The Kinman Dwarf galaxy, located in the Aquarius constellation, is too far away for astronomers to observe individual stars, but between 2001 and 2011, scientists detected the signatures of a massive, unstable star in the latter stages of its evolution.

In 2019, when astronomers at the European Southern Observatory’s Very Large Telescope and its ESPRESSO instrument focused on the faraway galaxy, there was no sign of a massive star.

Early observations of the star suggest it was a “luminous blue variable” star, measuring some 2.5 million times brighter than the sun at it brightest.

Luminous blue variable stars are known to fluctuate dramatically in their luminosity, but even when they dim, the stars produce spectrographic signatures that can be identified by astronomers. No such signatures were found in the 2019 VLT observations.

“It would be highly unusual for such a massive star to disappear without producing a bright supernova explosion,” lead researcher Andrew Allan, a doctoral student Trinity College Dublin in Ireland, said in a news release.

It’s possible the star dimmed before becoming obscured by thick intergalactic dust, but scientists suggest it’s also possible the star died an unusually quiet death.

“We may have detected one of the most massive stars of the local Universe going gently into the night,” said Jose Groh, an astronomer at Trinity College Dublin. “Our discovery would not have been made without using the powerful ESO 8-metre telescopes, their unique instrumentation, and the prompt access to those capabilities following the recent agreement of Ireland to join ESO.”

To determine the likely fate of the massive star, scientists returned to data collected by the Very Large Telescope’s UVES instrument between 2002 and 2009.

“The comparison of the 2002 high-resolution UVES spectra with our observations obtained in 2019 with ESO’s newest high-resolution spectrograph ESPRESSO was especially revealing, from both an astronomical and an instrumentation point of view,” said Andrea Mehner, staff astronomer at ESO.

The data showed the massive star brightened dramatically during the initial observation period. Luminous blue variable stars are known to shed large amounts of mass during outbursts.

It’s possible the star became a much less luminous version of itself after a period of outbursts — dim enough to be easily obscured by dust.

“Alternatively, the LBV could have collapsed to a massive black hole without the production of a bright supernova,” researchers wrote in the Monthly Notices of the Royal Astronomical Society.

To solve the cosmic mystery, scientists may have to wait until the next generation of powerful new telescopes come online — like the ESO’s Extremely Large Telescope, due to be unveiled in 2025. The ELT will be capable to imaging individual stars in distant galaxies like the Kinman Dwarf.



Source link

Science

SpaceX launches public beta test of Starlink Internet service

Published

on

Oct. 27 (UPI) — SpaceX has launched public beta testing of its Starlink communications satellite program that aims deliver high-speed Internet globally, particularly in underserved areas.

The Elon Musk-founded aerospace manufacturer sent out emails to invite people who signed up on its Starlink website to hear updates about the program.

The initial Starlink service is called “Better Than Nothing Beta,” according to multiple screenshots of an email, CNBC reported.

Joining the public beta test costs $99 a month on top of a $499 upfront cost for the ground equipment, which includes a user terminal to connect to the satellites, a mounting tripod and a Wi-Fi router.

SpaceX also has a Starlink app listed on the Google Play and Apple iOS app stores, which helps users set up their systems and allows them to search areas of the sky for unobstructed views.

“As you can tell from the title, we are trying to lower your initial expectations,” the Starlink Team signed email said. “Expect to see data speeds vary from 50 Mb/s to 150Mb/s and latency from 20ms to 40ms over the next several months as we enhance the Starlink system. There will also be brief periods of no connectivity at all.”

SpaceX said that “nearly 700,000” individuals across the United States had expressed interest in potentially subscribing to the service.

“Under Starlink’s Better Than Nothing Beta program, initial service is targeted for the U.S. and Canada in 2020, rapidly expanding to near global coverage of the populated world by 2021,” SpaceX said in the description of its Starlink mobile app.

The company rolled out private beta testing over the summer for which users had to agree to keep their experience confidential.

“You may NOT discuss your participation in the Beta Program online or with those outside or your household, unless they are SpaceX employees,” the Starlink website said.

SpaceX said the network will cost about $10 billion or more to build, but the company’s leadership estimates that it could bring in up to $30 billion a year, which is more than 10 times the annual revenue of its rocket business.

On Saturday, SpaceX launched its Falcon 9 rocket into space, carrying 60 Internet satellites into orbit to help establish connections to remote areas.

Earlier this month, Musk tweeted that Starlink’s constellation had grown large enough to begin beta-testing the Internet service system in the United States and southern Canada.

The company has launched nearly 900 Starlink satellites to date, which is only a fraction of what’s needed for global coverage, but enough to provide service in some areas.

Last week, SpaceX announced that it would offer Starlink’s broadband service free to families in Texas’ Ector County Independent School District, where more than one-third of the children and their families lack Internet access.



Source link

Continue Reading

Science

Pristine extraterrestrial organic compounds recovered from fallen fireball

Published

on

Oct. 27 (UPI) — On a cold winter night in 2018, when a fireball streaked across the skies above Canada and the Midwest, a team of meteor hunters turned to weather radar to pinpoint its likely landing spot.

The fireball had come to rest on a frozen lake in Michigan. Researchers raced to find it and, amazingly, they were able to collect remnants of the meteorite before its contents were tainted by exposure to Earthbound water molecules.

In a study published Tuesday in the journal Meteoritics and Planetary Science, scientists shared their analysis of pristine organic compounds recovered from the fallen space rock.

“We could see the minerals weren’t much altered and later found that it contained a rich inventory of extraterrestrial organic compounds,” lead study author Philipp Heck said in a news release.

“These kinds of organic compounds were likely delivered to the early Earth by meteorites and might have contributed to the ingredients of life,” said Heck, a curator at the Field Museum and an associate professor at the University of Chicago.

NASA’s weather radar typically helps meteorologists track precipitation, but because meteors fragment into rain- and snow-sized fragments as they travel through Earth’s atmosphere, the instruments can also be used to track pieces of meteorites.

With instructions from NASA scientists, meteorite hunter Robert Ward secured the first fragment from the frozen surface of Strawberry Lake, near Hamburg, Michigan.

Ward worked with fellow meteorite hunter Terry Boudreaux to get the space rock remnants to researchers at the Field Museum.

“When the meteorite arrived at the Field, I spent the entire weekend analyzing it, because I was so excited to find out what kind of meteorite it was and what was in it,” said study co-author Jennika Greer.

“With every meteorite that falls, there’s a chance that there’s something completely new and totally unexpected,” said Greer, a graduate student at the Field and the University of Chicago.

Researchers identified the meteorite as an H4 chondrite, a rarity. Just 4 percent of modern meteorites are H4 chondrites.

While most meteorite fragments are found weeks, months or — most often — years after they hit Earth, Ward collected the first remnants of the fireball just two days after it landed.

As a result, the meteorite pieces were largely uncontaminated.

“Scientists who study meteorites and space sometimes get asked, do you ever see signs of life? And I always answer, yes, every meteorite is full of life, but terrestrial, Earth life,” Heck said.

“As soon as the thing lands, it gets covered with microbes and life from Earth,” Heck said. “We have meteorites with lichens growing on them. So the fact that this meteorite was collected so quickly after it fell, and that it landed on ice rather than in the dirt, helped keep it cleaner.”

Researchers used a variety of analytical techniques to characterize the variety of pristine organic compounds found in the bits of freshly fallen space rock.

The authors of the new study suggest their discovery can help planetary scientists better understand how life-yielding compounds first arrived on primordial Earth.

“This study is a demonstration of how we can work with specialists around the world to get most out of the small piece of raw, precious piece of rock,” Heck said. “When a new meteorite falls onto a frozen lake, maybe even sometime this winter, we’ll be ready. And that next fall might be something we have never seen before.”



Source link

Continue Reading

Science

Longer-lingering droplets are less efficient carriers of COVID-19 virus

Published

on

Oct. 27 (UPI) — New research — published Tuesday in the journal Physics of Fluids — suggests bigger, short-lived aerosol droplets pose a much greater risk of spreading COVID-19 than aerosol microdroplets, which are tiny particles that linger longest in the air.

To better understand the behavior and virus-carrying potential of different types of aerosol droplets, researchers had volunteers breathe, speak and cough into a laser beam, which recorded the size and distribution of the array of aerosolized particles.

Researchers used a Rayleigh jet nozzle chip to generate the same distribution of droplets.

The jet released aerosol droplets composed of 1 percent glycerol and 99 percent ethanol into a chamber. A sheet of laser light running across the middle of the chamber allowed researchers to track the movements of different sized droplets as they moved through the chamber.

Researchers relied on computer models to analyze the disease transmission risk posed by different droplet sizes.

“What we used are simple models for the evaporation and sedimentation, or falling down, of the droplets,” lead study author Daniel Bonn told UPI in an email.

“Together with the measured drop size distribution, this allows us to model the concentration of aerosols in a given room as a function of the time since for instance a patient coughed,” said Bonn, a physicist and the director of the University of Amsterdam’s Van der Waals-Zeeman Institute.

Though microdroplets produced by breathing and talking can remain airborne for longer, they carry much less virus than larger droplets produced by coughs.

“The large drops that are the reason for social distancing are roughly a hundred times larger in diameter than the aerosols, and so contain a million times more virus,” Bonn said.

The models developed by Bonn and his colleagues showed the smallest, longest-lingering particles are relatively inefficient carriers of COVID-19.

That doesn’t mean airborne transmission can’t happen — however, the findings suggest the vast majority of airborne transmission isn’t happening at grocery stores, airports, or larger, well-ventilated public spaces.

According to Bonn and his colleagues, microdroplet transmission is most likely happening in poorly ventilated spaces where groups of people are spending long periods of time in close proximity.

“Avoid small ill-ventilated spaces with too many people in it, take care of good building ventilation, open doors and windows and so on,” Bonn said. “Identify and possibly isolate super-shedders.”

Scientists continue to gain new insights into the behavior to virus-carrying aerosols, including the effects of air flow and humidity on droplet movements, but a comprehensive understanding of the role different droplets play in COVID-19 transmission remains elusive.

“What is needed is a detailed understanding of the reproduction number R, that virologists, aerosol scientists and all other agree with,” Bonn said. “This will help fighting the pandemic, and that is what we need. We have provided a potentially important step towards this goal here, but much experimental, modeling and virology work remains.”



Source link

Continue Reading

Trending