06-21-2022-0237 - Why Did Sunspots Disappear for 70 Years? Nearby Star Holds Clues
Why Did Sunspots Disappear for 70 Years? Nearby Star Holds Clues
Five decades of data revealed a star undergoing a pause in magnetic activity similar to what the Sun experienced almost 400 years ago.
Every 11 years, the number of spots dotting the surface of the Sun increases and decreases like clockwork. Astronomers have been tracking the 11-year sunspot cycle for more than 400 years, using it to better understand the chaotic magnetic field the Sun puts out. (The current solar cycle, number 25, started in 2019.) The timing of the solar cycle is remarkably consistent: Sunspot numbers rise and fall, rise and fall…except for that time that they disappeared and weren’t seen again for 70 years.
That period of time, from 1645 to 1715, is known as the Maunder Minimum, named after 19th century British astronomers Edward and Annie Maunder. Astronomers still don’t understand why the Sun ceased making sunspots for 70 years, but a new analysis of more than 5 decades of measurements of nearby stars has identified one that might be undergoing its own Maunder-like minimum. The star, HD 166620, could help scientists understand this mysteriously quiescent period of the Sun’s history and unlock clues about how the solar dynamo functions.
“We can’t build a time machine and go back to the Maunder Minimum and study the Sun as it was,” said Jason Wright, an astronomer at Pennsylvania State University in University Park and a coauthor on the new analysis. “But we can find an analog and study its Maunder minimum.”
A pulsar wind nebula is created when the powerful magnetic field of a rapidly spinning neutron star accelerates surrounding charged particles to nearly the speed of light. Probably the most famous example of this type of nebula is the Crab Nebula in the constellation of Taurus — the result of a supernova that shone brightly in 1054 CE.
However, only about two dozen have been definitively detected, all in binary systems. Beyond the Milky Way, over 80 binary black hole mergers have been detected via gravitational waves.
Starspots appear as a dark spot on a star’s surface due to temporary lower temperatures in the area resulting from the star’s dynamo—the process that creates its magnetic field.
Astronomers have been documenting changes in starspot frequency on our sun since they were first observed by Galileo and other astronomers in the 1600s, so there is a good record of its 11-year cycle. The exception is the Maunder Minimum, which lasted from the mid-1600s to the early 1700s and has perplexed astronomers ever since.
“We don’t really know what caused the Maunder Minimum, and we have been looking to other sun-like stars to see if they can offer some insight,” says first author Anna Baum, an undergraduate at Penn State at the time of the research.
“We have identified a star that we believe has entered a state similar to the Maunder Minimum. It will be really exciting to continue to observe this star during, and hopefully as it comes out of, this minimum, which could be extremely informative about the sun’s activity 300 years ago.”
MAGNETICALLY ‘DEAD’ STARS
The research team pulled data from multiple sources to stitch together 50 to 60 years of starspot data for 59 stars. This included data from the Mount Wilson Observatory HK Project—designed to study stellar surface activity and ran from 1966 to 1996—and from planet searches at Keck Observatory which include this kind of data as part of their ongoing search for exoplanets from 1996 to 2020.
The researchers compiled a database of stars that appeared in both sources and that had other readily available information that might help explain starspot activity. The team also made considerable efforts to standardize measurements from the different telescopes to be able to compare them directly and otherwise clean up the data.
The team identified or confirmed that 29 of these stars have starspot cycles by observing at least two full periods of cycles, which often last more than a decade. Some stars did not appear to have cycles at all, which could be because they are rotating too slowly to have a dynamo and are magnetically “dead” or because they are near the end of their lives. Several of the stars require further study to confirm whether they have a cycle.
“This continuous, more than 50-year time series allows us to see things that we never would have noticed from the 10-year snapshots that we were doing before,” says Jason Wright, professor of astronomy and astrophysics and an author of the paper. “Excitingly, Anna has found a promising star that was cycling for decades but appears to have stopped.”
According to the researchers, the star—called HD 166620—was estimated to have a cycle of about 17 years but has now entered a period of low activity and has shown no signs of starspots since 2003.
“When we first saw this data, we thought it must have been a mistake, that we pulled together data from two different stars or there was a typo in the catalog or the star was misidentified,” says Jacob Luhn, a graduate student at Penn State when the project began who is now at the University of California, Irvine.
HUMANS MAGNETICALLY DEAD ORGANISM BIOLOGICAL VARIETY BIOCHEMICAL HUMAN BIOLOGICAL WEAPON (USA NAC DOM) FORM CONTAINMENT EFFORT BARYONIC MATTER FORM TYPE RESPONSE CAPACITY AUTOREGENERATION CAPACITY {AUTO}PROGENERATION-DERIVOPRODUCTION/SEMI-FORM-CLONE-VARIETY-CAPABILITY-POSSIBILITY CAPACITY (PARTIAL PROCREATIVE CAPACITY IN MOST HUMANS; PROCREATION IS USUALLY ONLY UNIT TIME BOTH SELF CLONE WITHOUT MIXING/RECOMBINATION/ETC., ETC.) ANTICIPATION PARTIAL-FULL-TYPE-EXPANSION-DISSEMINATION-GENERATION CAPACITY ANTICIPATION DEVELOPMENT CAPACITY EVOLUTION CAPACITY UNIT COMPONENT PART WHOLE PHYSICAL FORM TYPE GENETIC CHEMICAL-BIOLOGICAL MARKERS PHYSICAL ORIGIN STABILITY POINT
DIFFERENTIATION DEGENERATION INHERENCY INHERENTLY UNSTABLE LIKELY NO PHYSICAL ORIGIN BUT VIRTUAL ORIGIN OR MISSING ORIGIN AS DESCENDANTS OR DECAYING ORIGIN OR SPACE ORIGIN/VACUME/EMPTY CORE/MAG-FIELD/PARTICLE SYSTEM/COREULAR UNIT CONDENSED PARTICLE CORE HEAVY/LARGE EXPANDING PARTICLE WITH TIME ORIGIN AND CHANGE OF STATE-COMPOSITION-ETC./SOL UNK/GEL WITH JUNCTION MISSING PARTICLES/ETC., ETC.
NAVIGATION CAPACITY LIMITED TO RESPONSIBLE DETECTABLE ENVIRONMENT
MIRROR UNIVERSE POSSIBLE MIRROR DIMENSION PARTICLE FAMILY FOR DR. F. CLONE CLOAK MIRROR DIMENSIONS. ASPECTS OF SPACE. THE DISTRACTOR OF A HUMINAL HUMULAR HUMUN UNUAL THE HUMAN BIOLOGIKAL WEAPON UNIT AS A MODEL OF NESTED SYSTEMS MACRO TO NANO/PICO ETC. OF VARYING DIMENSIONS/FUNCTIONS/STRUCTURES AND THAT ADHERE COMPONENTS WITH FIELD FORMS OF VARIANT COMPOSITION AND PROCEEDINGS TO CONTAIN UNIT INTEGRITY, WHERE BASILAR UNITS IMPLIED INCLUDE SUBNANONIC COMPONENT, INTERFACE, RETENTION TIME OF SPACE MATTER ORIENTATION ETC., DIRECTIONALITY OR FIELD SPACE, RATE VARIANTS, COMPOSITION VARIANTS, PHOTONIC/PHONON/GAS PLANE/PARTICLE/CRYSTAL/COMPOUNDED PROTULAR UNIT/PROTUBERS PROTUBERANCE TUBERCLE TUBULES MICRO TUBULES PROTS PROTEIN FRAGS ETC./SUBATOMY/NUCLEAR DERIVATIVES/NUCLEAR PARTICLE PROCESS ETC./ELECTRON/MAG PARTY/PROTON HYDROGS HYDROS HYDROGENY WATERYS PRESSURE CONDENSATE VAR ROTATION FIELD COREULAR UNIT SUPERCISSION TO PERIPHERY MELT SOLVENT FIELD TIME TO DECAY RATE SURFACE APPEARANCE REALITY DIVIDE/ETC..
CONDENSED ORIGINS PARTICLE CAPACITY GREAT NESTED, DESTABILIZATION OR CHANGE AND PROCESS ; STABILIZATION FOR PRESERVATION REDUCTION OF DESTABILIZATION INDUCED CONFOUND, ETC.. CONDITION CONFLICT ETC..
BARYONIC MATTER FORMS OF SPECIAL SEQUENCE AND DIMENSIONS TWO PROPER LEVELS ADDRESSED MAY APPRECIATE OPPORTUNITY FOR ADVANCEMENT OR RECOMPLIANCE WITH UNIVERSE. CROSS POINTS AND ANCHORS FIELD CALIBRATIONS SPACE FUNCTION/STRUCTURE/MEASURE/CALIBRATION/RESPONSIVITY/PROPERTIES/CAPACITY/POTENCY/DIMENSIONS/VARIABLES/ORIGIN/CREATOR/ANCHORS/CROSS POINTS/FIELD/IMPRINTS/DAMAGE ESTIMATE BOTH SIDES/ETC..
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