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Dust Older Than the Sun Sheds Light on Galactic History

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Hidden inside the famous Murchison meteorite are motes of stardust older than the Sun. A new analysis measured the ages of these stardust grains, which include the oldest solid material on Earth. The research also has revealed clues about the Milky Way’s past and how dust travels from star to star.

“The most exciting part is to be able to study the star formation history of our galaxy with presolar minerals extracted from Murchison,” said lead researcher Philipp Heck, Pritzker Associate Curator at the Field Museum of Natural History in Chicago. “Stardust is the oldest material to reach Earth, and from it, we can learn about our parent stars, the origin of the carbon in our bodies, the origin of the oxygen we breathe,” he added in a statement. “With stardust, we can trace that material back to the time before the Sun.”

The Dust of Stars, Literally

How does stardust form, and how does it find its way into a meteorite bound for Earth? The process begins, as the name suggests, inside a star.

Stars at the asymptotic giant branch stage have four distinct layers. The innermost layer (blue) is a core of inert carbon and oxygen. The second layer (green) is helium fusing into carbon and oxygen. The third layer (yellow) is hydrogen fusing into helium. The outermost and coolest layer (red) is inert hydrogen. Credit: National Optical Astronomy Observatory/Association of Universities for Research in Astronomy/National Science Foundation

Just before it dies, a star whose mass is less than 10 times that of the Sun will have layers like an onion. The layers—made of carbon, oxygen, helium, and hydrogen—are either fusing new elements or collapsing under their own weight. At this stage of a star’s life, known as the asymptotic giant branch (AGB), the very top layers of the star’s atmosphere are cool enough for dust to condense. That is stardust.

During the last 100,000 years of its life, the AGB star will puff out its atmosphere to create a beautiful planetary nebula. Some of the stardust, propelled by the nebula’s expansion, will flow farther outward.

Stardust made up a tiny percentage of the interstellar soup that birthed our solar system. Less than 200 parts per million survived to be incorporated into the Sun, planets, comets, and asteroids.

And, in 1969, a 100-kilogram chunk of one carbonaceous chondrite bore some of that stardust to Murchison in Victoria, Australia.

As Old As Dust

Researchers ground down a small part of the meteorite into a fine powder and separated the stardust from the solar system dust by their chemical compositions. They then measured the ages of the microscopic particles by determining how long the grains had been exposed to high-energy galactic cosmic rays.

Exposure to high-energy cosmic rays changes the surfaces of dust grains traveling through the galaxy. Grains are more heavily coated with the isotopes helium-3 and neon-21 the longer they exist outside the solar system. (The Sun’s magnetic field shields the grains once they arrive.)

A gray scale image of a stardust grain
This speck of stardust, seen here in a scanning electron micrograph, condensed in the atmosphere of a dying star. It is silicon carbide and measures only 8 micrometers on its longest side. Credit: Janaína N. Ávila

About 60% of the newly discovered grains predate the solar system by only 300 million years. Adding the age of the Sun, the presolar age of the grains, and the time it takes a star to reach the AGB stage, this dating suggests that the stars that made these grains were born about 7 billion years ago.

Moreover, the team estimates that the stars that made these grains must have been between 2 and 3 times the mass of the Sun. Smaller stars wouldn’t have reached the AGB stage before the solar system formed, and the radiation from larger stars would have prevented the grains from growing as big as they did, the team argues.

Some of the grains show signs that they traveled the galaxy in large clusters, which is consistent with observations of objects like the Egg Nebula, said coauthor Jennika Greer, a graduate student researcher at the Field Museum. In addition, 8% of the grains dated in the study are more than a billion years older than the Sun. One grain is more than 3 billion years older than the Sun, which, at more than 7 billion years, makes it the oldest solid material on Earth.

These results were published in Proceedings of the National Academy of Sciences of the United States of America on 13 January.

Piecing Together Galactic History

Astronomers are still trying to figure out how often the Milky Way forms stars and whether the rate is constant or whether it fluctuates. Previous studies, some based on theory and some on observations, have pointed to a period of slightly enhanced star formation about 7 billion years ago.

“Our age distribution also supports a heterogeneous star formation rate, something that is supported in high-resolution models,” said Greer. “With presolar grains, we can analyze objects, like stars and supernovae, and events, like star formation, not normally accessible by laboratory studies.”

“An amazing aspect of this finding is that it is based on direct measurement of decay products, while generally the evidence…is based on indirect chronological methods, which are ultimately linked to a stellar model or statistical assumptions,” Helio Rocha-Pinto told The Guardian. “Yet they are the main tools we have for dating stars since we cannot take them to the laboratory.” Rocha-Pinto, an astronomer at Observatório do Valongo at the Federal University of Rio de Janeiro in Brazil, was not involved with this research.

This project analyzed 40 presolar grains from the meteorite. “We have already started separating more large, datable presolar grains from Murchison,” Heck said. The researchers hope that future grains will have ages that let them look further back in time.

“With more ages,” Greer added, “I believe we will be able to resolve discrete events in our galaxy in addition to our evidence for one period of increased star production, much like that in zircon geochronology for solar system and terrestrial samples.”

—Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer

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Province Announces Windsor Essex Is Moving To Red 'Control' Status – windsoriteDOTca News

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Ontario Ministry of Health graphic

The province of Ontario announced Friday that Windsor Essex will be moving to Red, or “Control” status under the province’s COVID-19 response framework.

The changes will come into effect on Monday, November 30th 12:01am.

“The health and safety of all Ontarians is and will always be our top priority, that’s why we are following the advice of the Chief Medical Officer of Health and other health experts and making this adjustment today,” said Christine Elliott, Deputy Premier and Minister of Health. “Over the last week we have seen a shift in the trends of key public health indicators in regions across the province, and by moving [regions to new levels] in the framework, we can ensure that the necessary targeted measures are in place to stop the spread of the virus and allow us to keep our schools and businesses open.”

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Windsor-Essex joins four other regions moving to different levels under the framework. Haldimand-Norfolk Health Unit is moving to Orange-Restrict, and Hastings Prince Edward Public Health, Lambton Public Health, and Northwestern Health Unit are moving to Yellow-Protect.

The Red status is one status away from the province’s Lockdown status.

Red ‘Control’ status means the following, according to the province:

Changes from Orange – Restrict to Red – Control are marked in red.

Organized public events, social gatherings and religious services, rites and ceremonies

  • Limits for all organized public events and social gatherings:
    • 5 people indoors
    • 25 people outdoors
  • Limits for religious services rites or ceremonies, including wedding services and funeral services (apply regardless of the venue where held):
    • 30% capacity of the room indoors
    • 100 people outdoors

Restaurants, bars and other food and drink establishments

  • Maximum number of patrons permitted to be seated indoors is 10
  • Outdoor dining, take out, drive through, and delivery permitted, including alcohol
  • Require patrons to be seated; 2 metre minimum or impermeable barrier required between tables
  • Limit of 4 people may be seated together
  • Dancing, singing and the live performance of music is prohibited
  • Require contact information for all seated patrons
  • No buffet style service
  • Line-ups and patrons congregating outside venues managed by venue; 2 metres distance and face covering required
  • Face coverings required except when eating or drinking only
  • Personal protective equipment, including eye protection required when is a worker must come within 2 metres of another person who is not wearing a face covering
  • Establishments must be closed from 10 p.m. to 5 a.m.
  • Liquor sold or served only between 9 a.m. to 9 p.m.
  • No consumption of liquor permitted between 10 p.m. to 9 a.m.
  • Limit volume of music to be low enough that a normal conversation is possible
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • Night clubs and strip clubs only permitted to operate as restaurant or bar
  • A safety plan is required to be prepared and made available upon request

Sports and recreational fitness facilities

  • Gyms and fitness studios permitted to be open with maximum of:
    • 10 people indoors or 25 people outdoors in classes; and
    • 10 people indoors in areas with weights or exercise equipment
  • No spectators permitted (exemption for parent and guardian supervision of children)
  • Increase spacing between patrons to 3 metres for areas of a sport or recreational facility where there are weights or exercise equipment and in exercise and fitness classes
  • Team sports must not be practiced or played except for training (no games or scrimmage)
  • Activities that are likely to result in individuals coming within 2 metres of each other are not permitted; no contact permitted for team or individual sports, with an exemption for high performance, including parasport, athletes.
  • Patrons may only be in the facility for 90 minutes except if engaging in a sport
  • Limit volume of music to be low enough that a normal conversation is possible; measures to prevent shouting by both instructors and members of the public
  • Face coverings required except when exercising
  • Require contact information for all members of the public that enter the facility
  • Require reservation for entry; one reservation for teams
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • A safety plan is required to be prepared and made available upon request

Meeting and event spaces

  • Maximum of 10 people per facility indoors or 25 outdoors
  • Booking multiple rooms for the same event not permitted
  • Establishments must be closed from 10 p.m. to 5 a.m.
  • Liquor sold or served only between 9 a.m. to 9 p.m.
  • No consumption of liquor permitted between 10 p.m. to 9 a.m.
  • Require contact information for all seated patrons
  • Limit of 4 people may be seated together
  • Limit volume of music to be low enough that a normal conversation is possible
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • A safety plan is required to be prepared and made available upon request

Retail

  • Fitting rooms must be limited to non-adjacent stalls
  • Line-ups and patrons congregating outside venues managed by venue; 2 metre distance required inside and outside; face covering also required while in line
  • Limit volume of music to be low enough that a normal conversation is possible
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • For malls:
    • Maximum number of patrons permitted to be seated indoors in mall food court is 10
    • A safety plan is required to be prepared and made available upon request

Personal care services

  • Oxygen bars, steam rooms, saunas, bath houses and other adult venues, closed
  • Sensory deprivation pods closed (some exceptions)
  • Services requiring removal of face coverings prohibited
  • Require contact information from all patrons
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • A safety plan is required to be prepared and made available upon request

Casinos, bingo halls and gaming establishments

  • Maximum of 10 people indoors or 25 people outdoors
  • Table games are prohibited
  • Liquor sold or served only between 9 a.m. to 9 p.m.
  • No consumption of liquor permitted between 10 p.m. to 9 a.m.
  • Require contact information from all patrons
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • A safety plan is required to be prepared and made available upon request

Cinemas

  • Closed, except for:
    • drive-in cinemas
    • rehearsal or performing a recorded or broadcasted event, with restrictions:
      • Performers and employees must maintain 2 metre physical distance except for purposes of the performance
      • Singers and players of brass or wind instruments must be separated from any other performers by plexiglass or other impermeable barrier
  • A safety plan is required to be prepared and made available upon request

Performing arts facilities

  • Closed to spectators
  • Rehearsal or performing a recorded or broadcasted event permitted
    • Performers and employees must maintain 2 metre physical distance except for purposes of the performance
    • Singers and players of brass or wind instruments must be separated from any other performers by plexiglass or other impermeable barrier
  • Drive-in performances permitted
  • A safety plan is required to be prepared and made available upon request

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Waterloo Region to remain in red (control) zone – KitchenerToday.com

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Waterloo Region will continue to stay in the red (control) zone of the province’s response framework, at least for now.

Just one new region will be moving into red on Monday, and that’s Windsor-Essex.

Waterloo Region was placed into the red zone on Monday, November 23.

Earlier this week, the region’s medical officer of health also issued a Section 22 order when it comes to malls and retail stores.

It requires them to ensure capacity is managed and actively monitored, such that adequate physical distancing can be maintained.

That order came into effect on Friday morning.

The active COVID-19 caseload in Waterloo Region is 460, the highest it has ever been.

Below are the control measures for red:

Organized public events, social gatherings and religious services, rites and ceremonies

  • Limits for all organized public events and social gatherings:
    • 5 people indoors
    • 25 people outdoors
  • Limits for religious services rites or ceremonies, including wedding services and funeral services (apply regardless of the venue where held):
    • 30% capacity of the room indoors
    • 100 people outdoors

Restaurants, bars and other food and drink establishments

  • Maximum number of patrons permitted to be seated indoors is 10
  • Outdoor dining, take out, drive through, and delivery permitted, including alcohol
  • Require patrons to be seated; 2 metre minimum or impermeable barrier required between tables
  • Limit of 4 people may be seated together
  • Outdoor dining, take out, drive through and delivery permitted
  • Dancing, singing and the live performance of music is prohibited
  • Require contact information for all seated patrons
  • No buffet style service
  • Line-ups and patrons congregating outside venues managed by venue; 2 metres distance and face covering required
  • Face coverings required except when eating or drinking only
  • Personal protective equipment, including eye protection required when a worker must come within 2 metres of another person who is not wearing a face covering
  • Establishments must be closed from 10 p.m. to 5 a.m.
  • Liquor sold or served only between 9 a.m. to 9 p.m.
  • No consumption of liquor permitted between 10 p.m. to 9 a.m.
  • Limit volume of music to be low enough that a normal conversation is possible
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • Night clubs and strip clubs only permitted to operate as restaurant or bar
  • safety plan is required to be prepared and made available upon request

Sports and recreational fitness facilities

  • Gyms and fitness studios permitted to be open with maximum of:
    • 10 people indoors or 25 people outdoors in classes; and
    • 10 people indoors in areas with weights or exercise equipment
  • No spectators permitted (exemption for parent and guardian supervision of children)
  • Increase spacing between patrons to 3 metres for areas of a sport or recreational facility where there are weights or exercise equipment and in exercise and fitness classes
  • Team sports must not be practiced or played except for training (no games or scrimmage)
  • Activities that are likely to result in individuals coming within 2 metres of each other are not permitted; no contact permitted for team or individual sports, with an exemption for high performance, including parasport, athletes.
  • Patrons may only be in the facility for 90 minutes except if engaging in a sport
  • Limit volume of music to be low enough that a normal conversation is possible; measures to prevent shouting by both instructors and members of the public
  • Face coverings required except when exercising
  • Require contact information for all members of the public that enter the facility
  • Require reservation for entry; one reservation for teams
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • safety plan is required to be prepared and made available upon request

Recreational facilities and community centres in Waterloo Region (update issued Friday) 

  • Indoor capacity of 10 program participants per room/space, provided physical distancing can be maintained.
  • Outdoor capacity of 25 program participants per space, provided physical distancing can be maintained.
  • Additional coaching and training staff are permitted, limited strictly to those officially rostered with the team/athletes as identified in their provincial association’s return to play protocols, provided physical distancing can be maintained.
  • No spectators permitted. Where previously allowed, one guardian per minor aged participant is permitted. Masks for guardians are mandatory, and physical distancing must be maintained.
  • Aquatics classes are limited to 10 participants per class. If physical distancing can be maintained and total pool capacity remains below 30%, more than one class may be in the pool at a time.
  • Mandatory active screening, contact information and attendance for all patrons.
  • Drop-in recreation programs (pre-registration is required) have a maximum capacity of 10 people. 
  • For all team sport, scrimmages and games are no longer permitted.
  • Teams must adjust their programming to training and skill development only, while meeting the required maximum capacity numbers.
  • No contact permitted for team or individual sports.
  • Community centre room rentals for church, funeral or wedding services are limited to 30% of room capacity.

Meeting and event spaces

  • Maximum of 10 people per facility indoors or 25 outdoors
  • Establishments must be closed from 10 p.m. to 5 a.m.
  • Liquor sold or served only between 9 a.m. to 9 p.m.
  • No consumption of liquor permitted between 10 p.m. to 9 a.m.
  • Require contact information for all seated patrons
  • Limit of 4 people may be seated together
  • Limit volume of music to be low enough that a normal conversation is possible
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • safety plan is required to be prepared and made available upon request

Retail

  • Fitting rooms must be limited to non-adjacent stalls
  • Line-ups and patrons congregating outside venues managed by venue; 2 metre distance required inside and outside; face covering also required while in line
  • Limit volume of music to be low enough that a normal conversation is possible
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • For malls:
    • Maximum number of patrons permitted to be seated indoors in mall food court is 10
    • safety plan is required to be prepared and made available upon request

Personal care services

  • Oxygen bars, steam rooms, saunas, bath houses and other adult venues, closed
  • Sensory deprivation pods closed (some exceptions)
  • Require contact information from all patrons
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • safety plan is required to be prepared and made available upon request

Casinos, bingo halls and gaming establishments

  • Maximum of 10 people indoors or 25 people outdoors
  • Table games are prohibited
  • Liquor sold or served only between 9 a.m. to 9 p.m.
  • No consumption of liquor permitted between 10 p.m. to 9 a.m.
  • Require contact information from all patrons
  • Screening of patrons is required, in accordance with instructions issued by the Office of the Chief Medical Officer of Health
  • safety plan is required to be prepared and made available upon request

Cinemas

  • Closed, except for:
    • drive-in cinemas
    • rehearsal or performing a recorded or broadcasted event, with restrictions:
      • Performers and employees must maintain 2 metre physical distance except for purposes of the performance
      • Singers and players of brass or wind instruments must be separated from any other performers by plexiglass or other impermeable barrier
  • safety plan is required to be prepared and made available upon request

Performing arts facilities

  • Closed to spectators
  • Rehearsal or performing a recorded or broadcasted event permitted
    • Performers and employees must maintain 2 metre physical distance except for purposes of the performance
    • Singers and players of brass or wind instruments must be separated from any other performers by plexiglass or other impermeable barrier
  • Drive-in performances permitted
  • safety plan is required to be prepared and made available upon request

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Earth is 2000 light years closer to supermassive black hole at the center of our galaxy than we thought – CTV News

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A new map of the Milky Way by Japanese space experts has put Earth 2,000 light years closer to the supermassive black hole at the center of our galaxy.

This map has suggested that the center of the Milky Way, and the black hole which sits there, is located 25,800 light-years from Earth. This is closer than the official value of 27,700 light-years adopted by the International Astronomical Union in 1985, the National Observatory of Japan said.

What’s more, according to the map, our solar system is traveling at 227 kilometers per second as it orbits around the galactic center — this is faster than the official value of 220 kilometers per second, the release added.

These updated values are a result of more than 15 years of observations by the Japanese radio astronomy project VERA, according to an announcement released Thursday from the National Observatory of Japan. VERA is short for VLBI Exploration of Radio Astrometry and refers to the mission’s array of telescopes, which use Very Long Baseline Interferometry to explore the three-dimensional structure of the Milky Way.

Because the Earth is located inside the Milky Way, it’s difficult to step back and see what the galaxy looks like. To get around this, the project used astrometry, the accurate measurement of the position and motion of objects, to understand the overall structure of the Milky Way and Earth’s place in it.

The black hole is known as Sagittarius A* or Sgr A* and is 4.2 million times more massive than our sun. The supermassive hole and its enormous gravitational field governs the orbits of stars at the center of the Milky Way. Reinhard Genzel and Andrea Ghez earned the 2020 Nobel prize for physics for its discovery. There are several types of black holes, and scientists believe the supermassive ones may be connected to the formation of galaxies, as they often exist at the center of the massive star systems — but it’s still not clear exactly how, or which form first.

MORE PRECISE APPROACH

In August, VERA published its first catalog, containing data for 99 celestial objects. Based on this catalog and recent observations by other groups, astronomers constructed a position and velocity map. From this map, the scientists were able to calculate the center of the galaxy, the point that everything revolves around.

VERA combines data from four radio telescopes across Japan. The observatory said that, when combined, the telescopes were able to achieve a resolution that in theory would allow the astronomers to spot a United States penny placed on the surface of the Moon.

To be clear, the changes don’t mean Earth is plunging toward the black hole, the observatory said. Rather, the map more accurately identifies where the solar system has been all along.

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