With data from the satellites Kepler (NASA), Gaia (ESA) and SOHO (NASA/ESA), a team led by Instituto Astrophysica y Ciencias do Espaco (IA) researcher Angela Santos appears to have put an end to this notion that the Sun may not be an ordinary “star-like”. by the sun.” The results were published today (April 6) in Astronomy and astrophysics.
Although it may seem strange to try to figure out whether the Sun is a sun-like star, Angela Santos, a researcher at IA, explains the problem: “In society, there is an ongoing debate about whether the Sun is a ‘sun’ like a star. In particular, Regarding its magnetic activity, many studies indicated that stars similar to the Sun were significantly more active.However, the problem does not seem to be with the Sun, but with stars classified as Sun-like.Because there are many limitations and biases in observational data and stellar characteristics inferred,” adds Santos.
For this work, the team selected several stars with similar properties to the Sun. The team used the new stellar properties catalog, from Kepler data, as well as some Gaia data and the team’s rotation period and magnetic activity index catalog. The stellar data was compared to activity data from the last two solar cycles, from the VIRGO/SPM instrument aboard the SOHO spacecraft.
One of the stars studied, which was selected from the Kepler catalog, astronomers named it Doris. In earlier work, the team had already noted that the amplitude of the Doris cycle was twice that of the Sun in recent solar cycles, even though Doris has similar properties to the Sun. Says Santos, “The difference was the metallicity. Our interpretation is that the metallicity effect, which leads to a deeper convection zone, produces a more efficient dynamo, which leads to a stronger activity cycle.”
For this work, when the team selected Doris-like stars, without considering metallicity in the selection, they found an excess of highly metallic stars. “In our selection, the only parameter that could lead to this excess is the period of rotation. In particular, Doris had a period longer than the Sun. In fact, we found evidence of a relationship between the period of rotation and metallicity,” says Santos.
The two studies found consistent results, because stronger magnetic activity means magnetic braking results in a slower rotation period, which explains why Doris rotates more slowly than the Sun, despite being very similar and slightly smaller than the Sun.
“What we found is that although there are stars that are more active than the Sun, the Sun is actually a completely normal, Sun-like star,” says Angela Santos.
ARG Santos et al, Temporal variation of the photomagnetic activity of the Sun and Kepler’s sun-like stars, Astronomy and astrophysics (2023). DOI: 10.1051/0004-6361/202245430
the quote: The Sun is a Natural Star After All, Study Confirms (2023, April 6) Retrieved April 6, 2023 from https://phys.org/news/2023-04-sun-star.html
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