Cosmicflows-4: These Astronomers Mapped Distances of 56,000 Galaxies

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2 years ago

October 5, 2022

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Astronomers have assembled the largest-ever compilation of high-precision galaxy distances, called Cosmicflows-4. Galaxies, such as the Milky Way, are the building blocks of the universe, each comprised of up to several hundred billion stars. Galaxies beyond our immediate neighborhood are rushing away, faster if they are more distant, which is a consequence of the expansion of the universe that began at the moment of the Big Bang. Measurements of the distances of galaxies, coupled with information about their velocities away from us, determine the scale of the universe and the time that has elapsed since its birth.

“Since galaxies were identified as separate from the Milky Way a hundred years ago, astronomers have been trying to measure their distances,” said Brent Tully, astronomer at the University of Hawaii at Manoa. “Now by combining our more accurate and abundant tools, we are able to measure distances of galaxies, and the related expansion rate of the universe and the time since the universe was born with a precision of a few per cent.”

From the newly published measurements, the researchers derived the expansion rate of the universe, called the Hubble Constant, or H0. The team’s study gives a value of H0=75 kilometers per second per megaparsec or Mpc (1 megaparsec = 3.26 million light years), with very small statistical uncertainty of about 1.5 percent.

There are a number of ways to measure galaxy distances. Generally, individual researchers focus on an individual method. The Cosmicflows program spearheaded by Tully and Kourkchiincludes their own original material from two methods, and additionally incorporates information from many previous studies. Because Cosmicflows-4 includes distances derived from a variety of independent, distinct distance estimators, intercomparisons should mitigate against a large systematic error.

Astronomers have assembled a framework that shows the universe’s age to be a little more than 13 billion years old, however, a dilemma of great significance has arisen in the details.

Physics of the evolution of the universe based on the standard model of cosmology predicts H0=67.5 km/s/Mpc, with an uncertainty of 1 km/s/Mpc. The difference between the measured and predicted values for the Hubble Constant is 7.5 km/s/Mpc – much more than can be expected given the statistical uncertainties. Either there is a fundamental problem with our understanding of the physics of the cosmos, or there is a hidden systematic error in the measurements of galaxy distances.

Cosmicflows-4 is also being used to study how galaxies move individually, in addition to flowing with the overall expansion of the universe. Deviations from this smooth expansion arise due to the gravitational influences of clumps of matter, on scales ranging from our Earth and Sun up to congregations of galaxies on scales of a half billion light years. The mysterious dark matter is the dominant component on larger scales. With knowledge of the motions of galaxies in response to the mass around them, we can recreate the orbits that galaxies have followed since they were formed, giving us a better understanding of how the universe’s vast, dark-matter-dominated structures have formed over the eons of time.

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Science

Will Earth’s Gravity Alter Apophis Asteroid in 2029? Find Out!

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2 hours ago

November 14, 2024

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Will Earth’s Gravity Alter Apophis Asteroid in 2029? Find Out!

A close encounter between Earth and asteroid 99942 Apophis is expected to take place in April 2029. Named after an ancient Egyptian deity associated with darkness and disorder, Apophis will pass within 32,000 kilometres (20,000 miles) of Earth. According to recent simulations by Johns Hopkins University Applied Physics Laboratory, this event could cause significant shifts on the asteroid’s surface due to Earth’s gravitational influence.

Surface Disturbance Predicted by Simulation

The study was led by planetary scientist Dr Ronald Ballouz and was published The Planetary Science Journal. It suggests that Apophis‘ proximity to Earth might create seismic disturbances on its surface. These effects could cause surface movements that are measurable from Earth, giving scientists an unprecedented opportunity to observe near-Earth asteroids in a unique way. The asteroid, approximately 335 metres (1,100 feet) across, was initially calculated to be on a potential collision course with Earth upon its discovery in 2004. Current analysis has confirmed that there is no threat of impact in the foreseeable future.

Possible Impact on the Asteroid’s Rotation

As per a report by Space.com, another expected outcome is a change in Apophis’ rotational state. As it nears Earth, gravitational forces may alter its spin, which could result in surface reshaping as the asteroid continues orbiting the Sun over time. Past research has noted that asteroids showing less space-weathering than anticipated, like 25143 Itokawa, may owe these qualities to close planetary flybys. This particular flyby will thus allow scientists to study such transformations directly.

An Opportunity for Observation

As Apophis is projected to be visible without telescopes during its approach. As reported, researchers anticipate capturing detailed images of any changes. The findings from this study are expected to deepen understanding of how close encounters impact near-Earth objects, potentially influencing future research and asteroid-monitoring efforts.

Science

NASA Astronaut Sunita Williams Refutes Health Concerns Amid ISS Mission

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14 hours ago

November 13, 2024

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NASA Astronaut Sunita Williams Refutes Health Concerns Amid ISS Mission

NASA astronaut Sunita Williams has recently addressed speculations surrounding her health condition while on the International Space Station (ISS), discarding recent claims made by media outlets regarding her wellbeing. In response to reports that suggested she appeared “gaunt” due to an extended stay on the ISS, Williams clarified her status during a video interview on November 12, explaining that her weight has remained unchanged since her arrival in orbit.

Routine Exercise and Physical Adaptations

Williams, who commands Expedition 72 aboard the ISS, responded to health concerns publicly, indicating that any changes in her physical appearance are the result of rigorous exercise routines rather than health deterioration. Like all astronauts on extended missions, she has been following an intense workout regimen designed to counteract the muscle and bone density loss commonly associated with prolonged microgravity exposure. Williams stated that her routine includes running on a treadmill, riding an exercise bike and lifting weights. It is a form of exercise that has led to increased muscle mass, particularly in her thighs and glutes, while her overall weight remains consistent.

NASA’s Statement on Crew Health

NASA had previously denied the reports, emphasising that Williams and her fellow crew members, including NASA astronaut Butch Wilmore, are in good health. Williams and Wilmore, who arrived at the ISS on June 6 aboard Boeing’s Starliner capsule, were initially scheduled for a ten-day mission under the Crew Flight Test programme. Technical issues with Starliner’s thrusters led NASA to extend their stay on the ISS until early 2025, when they are expected to return with SpaceX’s Crew-9 mission astronauts.

Current ISS Crew Status

The current ISS team, led by Williams, includes three NASA astronauts and three Russian cosmonauts, all working collaboratively despite recent media scrutiny. Williams assured viewers that her health and morale remain robust as the crew carries out essential research and maintenance tasks on the orbiting laboratory showing NASA’s confidence in their well-being during extended missions.

Science

Math reveals secrets to gaining height on a half-pipe

Published

17 hours ago

November 13, 2024

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Math reveals secrets to gaining height on a half-pipe

A recent study reveals how skateboarders can use mathematical insights to increase their speed and height on half-pipes. Florian Kogelbauer, a mathematician from ETH Zurich, and his research team have examined how specific movements impact a skateboarder’s performance on U-shaped ramps. By alternating between crouching and standing in certain areas, skaters can generate extra momentum, leading to higher jumps and faster speeds. This research, published in Physical Review Research, could lead to more efficient techniques for skaters aiming to improve their skills.

Modelling Momentum on Half-Pipes

The research was published in American Physical Society Journal. The technique of “pumping,” or alternating between crouching and standing, is essential for building speed on half-pipes. Kogelbauer’s team created a model to show how the body’s centre of mass affects movement on a ramp, much like the mechanics of a swing. In their calculations, they found that crouching while moving downhill and standing while moving uphill helps skaters gain height more effectively. This rhythm, the team suggests, could help skaters reach higher elevations on the ramp in fewer motions.

Testing the Theory with Real Skaters

To test the model’s validity, researchers observed two skateboarders as they navigated a half-pipe. They were asked to reach a specific height as quickly as possible. Video analysis revealed that the more experienced skater naturally followed the model’s suggested pattern, reaching the target height with fewer motions. The less experienced skater, who did not follow the pattern as precisely, required more time to reach the same height. This contrast suggests that experienced skaters intuitively apply these principles for better performance.

Broader Applications Beyond Skateboarding

According to Sorina Lupu, an engineer at the California Institute of Technology, this simplified model may also have applications in robotics. By demonstrating how minimal adjustments in body position can impact speed and height, this study offers insights that could make robotic movement more efficient. For engineers, this research indicates that straightforward models of human movement could be used to enhance robotic performance, providing an alternative to complex machine-learning models often used in robotics.