astronomy

Astronomers use novel technique to find starspots

Published

2 months ago

February 4, 2023

New method seen as powerful tool in studying stars

Newswise — COLUMBUS, Ohio – Astronomers have developed a powerful technique for identifying starspots, according to research presented this month at the 241st meeting of the American Astronomical Society.

Our sun is at times dotted with sunspots, cool dark regions on the stellar surface generated by strong magnetic fields, which suppress churning motions and impede the free escape of light. On other stars, these phenomena are called starspots, said Lyra Cao, lead author of the study and a graduate student in astronomy at The Ohio State University.

“Our study is the first to precisely characterize the spottiness of stars and use it to directly test theories of stellar magnetism,” said Cao. “This technique is so precise and broadly applicable that it can become a powerful new tool in the study of stellar physics.”

Use of the technique will soon allow Cao and her colleagues to release a catalog of starspot and magnetic field measurements for more than 700,000 stars – increasing the number of these measurements available to scientists by three orders of magnitude.

Since sunspots were first discovered in the 17th century, scientists have typically detected signatures of stellar magnetism indirectly, by looking at stars through different filters or detecting the modulation of spots in a star’s light curve. But by analyzing legacy high-resolution infrared spectra from the Sloan Digital Sky Survey, Cao was able to develop a technique for identifying starspots in 240 stars from two open star clusters, the Pleiades and M67.

The study showed that precision starspot measurements are a powerful new class of data which could help researchers understand how stellar magnetic fields work. Due to precision of the technique, Cao was also able to see how age and rotation affected the magnetic fields on these stars.

“It was lurking in plain sight: Within the spectrum, there was a cooler component corresponding to the starspot which was only visible in the infrared,” Cao said.

As it turns out, younger stars can be enveloped in starspots – some of them more “spot” than star, with 80% of their surfaces covered. During her studies, Cao realized that these larger cooler regions may block so much light, it might have a measurable effect on these stars. Since the light must eventually escape, she said, the star compensates by expanding and cooling enough to make more surface area available for radiation.

Researchers also found that relying on classical methods to estimate the temperatures of these stars could be wrong by more than 100 degrees. Because scientists often rely on a star’s temperature when trying to estimate its size, astronomers could wrongly assume the radius of the star is smaller than it actually is.

“When this happens, you start seeing large changes in the stars’ structure, which can throw other important astronomical measurements off as well,” said Cao. As scientists use stellar parameters to understand our solar neighborhood and galaxy, and at times, the sizes and habitability prospects of nearby exoplanets, this method could dramatically improve researchers’ ability to test other scientific theories.

Additionally, researchers found a class of stars that are too active for standard theories to explain in the Pleiades cluster. According to Cao, these stars are not only magnetic and rife with starspots, but also overflowing with UV and X-ray radiation.

“You wouldn’t want to live around these stars,” said Cao. “But understanding why these stars are so active could change our models and criteria for exoplanetary habitability.” Further study of these unusual stars could hold the key for understanding why low mass stars are so active, the study notes.

“We can directly study the evolution of stellar magnetism in hundreds of thousands of stars with this new dataset, so we expect this will help develop key insights in our understanding of stars and planets,” said Cao.

Marc Pinsonneault, a professor of astronomy at Ohio State, co-authored the study. This work was supported by NASA.

Contact: Lyra Cao, [email protected]

Written by: Tatyana Woodall, [email protected]

Source: Ohio State University

astronomy

A Spectacular Aurora dazzles Skywatchers

Geomagnetic storm on the sun caused a stunning display of the Aurora Borealis to be visible as far south as New Mexico, Arizona, Oklahoma, and Virginia.

Published

12 hours ago

March 28, 2023

Rod Washington

On March 23, 2023, a geomagnetic storm on the sun caused a stunning display of the Aurora Borealis to be visible as far south as New Mexico, Arizona, Oklahoma, and Virginia. The Northern Lights, a natural phenomenon caused by charged particles from the sun interacting with the Earth’s magnetic field, are usually only visible in the far north. However, this storm caused a rare opportunity for those in more southern regions to witness the incredible light show.

Earth-Sky: https://earthsky.org/earth/aurora-photos-geomagnetic-storm-march-23-24-2023/

Aurora photos from Thursday’s geomagnetic storm

https://stmdailynews.com/category/science/

astronomy

Newly discovered comet to flyby Earth

Published

2 weeks ago

March 12, 2023

Hal Machina

Astronomers have recently spotted a newly-referenced comet C/2023 A3 that is heading towards the Earth. C/2023 A3 (Tsuchinshan–ATLAS) is a comet from the Oort cloud discovered by ATLAS South Africa on 22 February 2023 and independently found in images by the Purple Mountain Observatory taken on 9 January 2023.

The comet has a retrograde orbit, lying at an inclination of 139°. Τhe comet has its perihelion at a distance of 0.391 AU and the closest approach to Earth will be around 12 October 2024, at a distance of 0.47 AU. The comet doesn’t approach close to the giant planets of the solar system. Its orbit is weakly hyperbolic before entering the planetary region of the Solar System. Due to planetary perturbations, the outbound orbit will have a greater eccentricity than the inbound orbit.

By Филипп Романов (Filipp Romanov) – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=129174444

According to the latest observations, C/2023 A3 has an estimated diameter of 1.2 kilometers (0.75 miles) and is currently traveling at a speed of about 20 kilometers per second (12.4 miles per second). When it makes its closest approach to the Earth, C/2023 A3 will be about 0.47 AU away from our planet and will be brighter than the “green comet” from earlier this year. That translates to an opportunity for amateur astronomers to easily spot the comet in the sky.

While C/2023 A3 is not expected to pose a direct threat to the Earth, it is still an important object of study for astronomers. Comets are remnants of the early solar system, and they contain valuable information about the conditions and processes that occurred during its formation.

One of the main goals of studying comets is to understand the origin of water and other volatile compounds on Earth. It is believed that these substances were brought to our planet by comets and asteroids that collided with it billions of years ago.

In addition to studying the composition of comets, astronomers also use them as probes to explore the outer reaches of the solar system. By analyzing the trajectory and behavior of comets, they can gain insights into the dynamics and structure of the solar system as a whole.

C/2023 A3 is just one of many comets that have been discovered in recent years, and it highlights the importance of continued efforts to monitor and study these celestial objects. As our knowledge of comets grows, so too does our understanding of the early solar system and the conditions that led to the emergence of life on Earth.

In conclusion, the discovery of C/2023 A3 is an exciting development for astronomers, and it provides an opportunity to learn more about the composition and behavior of comets. While it is not expected to pose a direct threat to the Earth, it serves as a reminder of the importance of monitoring and studying near-Earth objects to ensure the safety of our planet.

https://en.wikipedia.org/wiki/C/2023_A3_(Tsuchinshan%E2%80%93ATLAS)

https://stmdailynews.com/category/science/

Sources: wikipedia, Earth-Sky

New comet – C/2023 A3 – could be bright in 2024

astronomy

Did you see the Conjunction?

Published

4 weeks ago

March 2, 2023

Rod Washington

Trying to see the astronomical events in the sky lately has been a challenge here in Phoenix due to the weather activity lately. Now that the clouds have cleared above us here in the Valley of the Sun for now, and we can now see the sky. Hopefully you caught as glimpse of the planetary conjunction of Venus and Jupiter.

In astronomy, a conjunction occurs when two astronomical objects or spacecraft have either the same right ascension or the same ecliptic longitude, usually as observed from Earth.

When two objects always appear close to the ecliptic—such as two planets, the Moon and a planet, or the Sun and a planet—this fact implies an apparent close approach between the objects as seen in the sky. A related word, appulse, is the minimum apparent separation in the sky of two astronomical objects.

Conjunctions involve either two objects in the Solar System or one object in the Solar System and a more distant object, such as a star. A conjunction is an apparent phenomenon caused by the observer’s perspective: the two objects involved are not actually close to one another in space. Conjunctions between two bright objects close to the ecliptic, such as two bright planets, can be seen with the naked eye.

The astronomical symbol for conjunction is (Unicode U+260C ☌). The conjunction symbol is not used in modern astronomy. It continues to be used in astrology. (wikipedia)