An image of the Heliospheric Imager aboard NASA’s STEREO spacecraft shows the star Betelgeuse, round. For several weeks in 2020, STEREO was the only observatory that made measurements of Betelgeuse because of the unique position of the spacecraft. Credit: NASA / STEREO / HI
For several weeks in the summer of 2020, NASAThe Observatory for Solar and Terrestrial Relations, or STEREO, had the best view of the solar system of the star Betelgeuse, whose extreme dimming has interested scientists in recent months. STEREO’s measurements revealed more unexpected dimming by the star, further adding to the questions about Betelgeuse’s recent behavior.
Beginning in late spring of 2020, Betelgeuse appeared in the sky near the Sun due to the Earth’s position in space. However, the STEREO spacecraft is currently located about 70 degrees from Earth – which means that STEREO was in about the same position at the end of June as Earth was in mid-April, and could therefore see the stars in April appeared in the night sky of the Earth.
This figure shows measurements of the brightness of Betelgeuse from various observers from late 2018 until today. The blue and green dots represent data from ground-based observers. The holes in these measurements occur when Betelgeuse appears in the earth’s day sky, making it impossible to take accurate measurements for clarity. At this observation hole in 2020, NASA’s STEREO spacecraft – with measurements shown in red – stepped in to observe Betelgeuse from its unique vantage point, and revealed unexpected dimming by the star. STEREO’s 2018 data point was found in the mission’s archive data and was used to calibrate STEREO’s measurements against other telescopes. Credit: Dupree, et al
Scientists took advantage of this unique orbital position to hold tabs over Betelgeuse, while the star was invisible to Earth-colored observatories. During this period between late June and early August, STEREO observed Betelgeuse on five separate days, and the spacecraft rolled about two hours each time to place Betelgeuse in the field of view of STEREO’s Heliospheric Imager, a tool normally used for imagery. of the sun’s emitting material, the sun wind, as it travels through the spaceship and toward Earth. The team shortened the exposure time of the instrument to take into account the relative brightness of Betelgeuse compared to the sun of wind. The instrument’s wide field of view occupies about 70 degrees of air, allowing scientists to calibrate their measurements with rigid stars in the night sky over several weeks.
STEREO’s measurements showed Betelgeuse dimming again – an unexpected development so soon after its last dimming period. Betelgeuse normally goes through brightness cycles that last about 420 days, with the previous minimum in February 2020, which means that this dimming happens unexpectedly early. These observations were reported by the science team via The Astronomer’s Telegram on July 28, 2020. This is an intriguing phenomenon that scientists will study with additional terrestrial orbiting and ground-based observatories when Betelgeuse returns to the night sky in late August.
This four-panel graph illustrates how the southern region of the fast-evolving, bright, red redundant star Betelgeuse in late 2019 and early 2020 suddenly became more beautiful in the first two panels, as seen in ultraviolet light. with the Hubble Space Telescope, a bright, warm blob of plasma is emitted from the formation of an enormous convection cell on the surface of the star. In panel three, the outflowing, expelled gas expands outward. It cools to form an enormous cloud of hidden dust grains. The final panel reveals the enormous cloud of dust that blocks the light (as seen from Earth) of a quarter of the star’s surface. Illustration credit: NASA, ESA, and E. Wheatley (STScI)
Is a Supernova Immediate?
The red supergiant is destined to end his life in a supernova explosion. Some astronomers think that the sudden dimming may be a pre-supernova event. The star is relatively close, about 725 light-years away, which means that dimming would have occurred around the year 1300. But the light is just now reaching the Earth.
“Nobody knows what a star does just before the supernova goes, because it’s never been observed,” Andrea Dupree, associate director of the Center for Astrophysics | Harvard & Smithsonian (CfA), Cambridge, Massachusetts, explained. “Astronomers have been collecting stars, maybe a year before they become supernovae, but not within days or weeks before it happened. But the chance that the star will supernova at any moment is quite small. ”
Read Hubble’s Finding Cause for Betellegeuse’s Mysterious Dimming for more research on Betelgeuse’s recent dimming.
