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Space News: Record-shattering cosmic blast could help crack the case of extreme supernova explosions
Records are made to be broken, as the expression goes, but rarely are records left so thoroughly in the dust.
Stunned astronomers have witnessed a cosmic explosion about 200 times more powerful than a typical supernova – events which already rank amongst the mightiest outbursts in the universe – and more than twice as luminous as the previous record-holding supernova.
At its peak intensity, the explosion – called ASASSN-15lh – shone with 570 billion times the brightness of the Sun.
If that statistic does not impress, consider that this luminosity level is approximately 20 times the entire output of the 100 billion stars comprising our Milky Way galaxy.
The record-breaking blast is thought to be an outstanding example of a “superluminous supernova,” a recently discovered, supremely rare variety of explosion unleashed by certain stars when they die.
Scientists are frankly at a loss, though, regarding what sorts of stars and stellar scenarios might be responsible for these extreme supernovae.
As described in a new study published today in Science, ASASSN-15lh is amongst the closest superluminous supernovae ever beheld, at around 3.8 billion light years away.
Given its uncanny brightness and closeness, ASASSN-15lh might offer key clues in unlocking the secrets of this baffling class of celestial detonations.
“ASASSN-15lh is the most powerful supernova discovered in human history,” said study lead author Subo Dong, an astronomer and a Youth Qianren Research Professor at the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University. “The explosion's mechanism and power source remain shrouded in mystery because all known theories meet serious challenges in explaining the immense amount of energy ASASSN-15lh has radiated.”
ASASSN-15lh was first glimpsed in June 2015 by twin telescopes with 14-centimeter diameter lenses in Cerro Tololo, Chile conducting the All Sky Automated Survey for SuperNovae (ASAS-SN), an international collaboration headquartered at the Ohio State University. (Hence ASASSN-15lh's somewhat menacing moniker).
These two tiny telescopes sweep the skies to detect suddenly appearing objects like ASASSN-15lh that are intrinsically very bright, but are too far away for human observers to notice.
“ASAS-SN is the first astronomical project in history to frequently scan the entire optical sky for optical transients,” said Krzysztof Stanek, professor of astronomy at the Ohio State University and the co-principal investigator of ASAS-SN. “Every time in science we open up a new discovery space, exciting findings should follow. The trick is not to miss them.”
Dong and colleagues immediately put out word about the sighting of ASASSN-15lh in order for as much data as possible to be gathered.
Multiple, far larger ground-based telescopes across the globe, as well as NASA's Swift satellite, have since taken part in an intense observing campaign that continues to this day.
In just the first four months after it went kablooie, so much energy beamed out of ASASSN-15lh that it would take our Sun in its current state more than 90 billion years to equal its emissions.
By examining this bright, slowly fading afterglow, astronomers have gleaned a few basic clues about the origin of ASASSN-15lh.
Using the 2.5-meter du Pont telescope in Chile, Dong's colleagues Ben Shappee and Nidia Morrell at the Carnegie Observatories in the United States took the first spectrum of ASASSN-15lh to identify the signatures of chemical elements scattered by the explosion.
This spectrum puzzled the ASAS-SN team members, for it did not resemble any of spectra from the 200 or so supernovae the project had discovered to date.
Inspired by suggestions from Jose Prieto at Universidad Diego Portales and Millennium Institute of Astrophysics in Chile and Stanek, Dong realized that ASASSN-15lh might in fact be a superluminous supernova.
Dong found a close spectral match for ASASSN-15lh in a 2010 superluminous supernova, and if they were indeed of a kind, then ASASSN-15lh's distance would be confirmable with additional observations.
Nearly 10 days passed as three other telescopes, stymied by bad weather and instrument mishaps, attempted to gather these necessary spectra.
Finally, the 10-meter South African Large Telescope (SALT) secured the observations of elemental signatures verifying ASASSN-15lh's distance and extreme potency.
“Upon seeing the spectral signatures from SALT and realizing that we had discovered the most powerful supernova yet, I was too excited to sleep the rest of the night,” said Dong, who had received word of the SALT results at 2 AM in Beijing on July 1, 2015.
The ongoing observations have further revealed that ASASSN-15lh bears certain features consistent with “hydrogen-poor” (Type I) superluminous supernovae, which are one of the two main types of these epic explosions so named for lacking signatures of the chemical element hydrogen in their spectra.
ASASSN-15lh has likewise shown a rate of temperature decrease and radius expansion similar to some previously discovered Type I superluminous supernova.
Yet in other ways, besides its brute power, ASASSN-15lh stands apart. It is way hotter, and not just brighter, than its apparently nearest of supernova kin.
The galaxy it calls home is also without precedent. Type I superluminous supernova seen to date have all burst forth in dim galaxies both smaller in size and that churn out stars much faster than the Milky Way.
Noticing the pattern, astronomers hoped this specific sort of galactic environment had something to do with superluminous supernovae, either in the creation of the exotic stars that spawn them or in setting these stars off.
Exceptionally, however, ASASSN-15lh's galaxy appears even bigger and brighter than the Milky Way. On the other hand, ASASSN-15lh might in fact reside in an as-yet-unseen, small, faint neighboring galaxy of its presumed, large galactic home.
To clear up where exactly ASASSN-15lh is located, as well as numerous other mysteries regarding it and its hyper-kinetic ilk, the research team has been granted valuable time this year on the Hubble Space Telescope.
With Hubble, Dong and colleagues will obtain the most detailed views yet of the aftermath of ASASSN-15lh's stunning explosion. Important insights into the true wellspring of its power should then come to light.
One of the best hypotheses is that superluminous supernovae's stupendous energy comes from highly magnetized, rapidly spinning neutron stars called magnetars, which are the leftover, hyper-compressed cores of massive, exploded stars.
But ASASSN-15lh is so potent that this compelling magnetar scenario just falls short of the required energies. Instead, ASASSN-15lh-esque supernovae might be triggered by the demise of incredibly massive stars that go beyond the top tier of masses most astronomers would speculate are even attainable.
“The honest answer is at this point that we do not know what could be the power source for ASASSN-15lh,” said Dong. “ASASSN-15lh may lead to new thinking and new observations of the whole class of superluminous supernova, and we look forward to plenty more of both in the years ahead.”
LAKE COUNTY, Calif. – Due to heavy rains expected in the coming days, the National Weather Service has issued a flash flood watch that is in effect from Sunday morning through early Monday morning in the area of the Valley, Rocky and Jerusalem fire burn areas.
There was a slight break in the rain on Friday, but more rain arrived on Friday night and early Saturday morning, with forecasters anticipating light to moderate rainfall with this latest system.
The National Weather Service reported 24-hour rainfall totals for the county through 3 a.m. Saturday that averaged about a third of an inch countywide.
However, a much wetter Pacific storm system is expected to move through Northern California Sunday and Sunday night, potentially bringing with it heavy rain – possibly several inches in the foothills and mountains, with several inches of snow also expected above the 6,000-foot elevation level, the National Weather Service reported.
The specific forecast for Lake County said that 1 to 2 inches of rain are possible on Sunday alone, and several inches overall during the course of the week.
Storms are forecast to continue Monday and Tuesday, with a break on Wednesday, and the potential for still more rain late in the week.
Forecasters warned that any residents of the burn areas – or anyone traveling through them – be particularly vigilant as flooding conditions could develop quickly, leading to a dangerous situation.
In those areas, be on the lookout for potential flooding, rock and debris flows if rainfall is heavy, forecasters said.
Temperatures over the next several days are expected to range into the low 50s in the daytime and into the low 40s at night, according to the forecast.
Clear Lake's level continues to rise thanks to the rain, passing 2.50 feet Rumsey early Saturday, up from just under 2 feet Rumsey a week ago, according to the US Geological Survey.
What that is still short of the 2.83 feet Rumsey recorded on Jan. 16 of last year, the lake is looking far better than it did on this date in 2014, when the depth was 0.59 feet Rumsey, based on survey records.
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CLEARLAKE OAKS, Calif. – Two local men were arrested on Thursday night in a case that began with the discovery of a stolen car and led to Lake County Sheriff's deputies finding marijuana and methamphetamine.
Lt. Steve Brooks of the Lake County Sheriff's Office said deputies arrested 41-year-old Matthew Alan Labrash of Lakeport and Fred Ralph Pearl, 35, of Upper Lake.
At 9:30 p.m. Thursday a deputy was patrolling the Clearlake Oaks area when he observed a gray Chevrolet Impala idling in the middle of the road in the 100 block of Schindler Street. Brooks said a records check of the vehicle revealed that it was reported stolen.
The deputy contacted a male subject sitting in the front passenger seat, who he identified as Labrash, as well as Pearl of Upper Lake, who was at a nearby residence, Brooks said.
Brooks said Pearl admitted being the owner and the driver of the vehicle, telling the deputy he purchased the vehicle from a female for $5,500.
However, Pearl was unable to provide a telephone number or any additional information concerning the female or any paperwork showing he was the current owner of the vehicle, Brooks said.
The deputy noticed the vehicle was a 2015 model in new condition and that it was registered to a rental company in Southern California. When the deputy asked Pearl if he suspected the vehicle might be stolen, Pearl replied that he thought he just got a great deal, according to Brooks.
A second deputy arrived on scene to assist with the investigation, Brooks said. During a pat search of Labrash, one of the deputies located a glass methamphetamine pipe concealed in one of his socks.
While the deputies were standing at the passenger side of the vehicle talking to Labrash, Brooks said they could smell the strong odor of marijuana emitting from inside the vehicle.
Inside the trunk of the vehicle deputies located a black plastic trash bag which contained four separate bags of processed marijuana. They also located a clear one gallon bag in the center console which also contained processed marijuana, according to Brooks.
In the backseat of the vehicle beneath a child’s booster seat, the deputies located a red rubber tray which contained a large amount of concentrated cannabis, Brooks said.
Brooks said the deputies located and seized a total of 3.5 pounds of processed marijuana and 2.38 pounds of concentrated cannabis from inside the vehicle and 2.2 grams of methamphetamine from the glass pipe.
Labrash claimed ownership of all the marijuana located in the vehicle and said it was for his personal use, Brooks said. The deputy asked why he was riding around with such a large amount of marijuana in the vehicle and Labrash stated “No comment.”
Brooks said Labrash was arrested for possession of marijuana for sale, transportation of marijuana, possession of concentrated cannabis, possession of controlled substance paraphernalia and possession of a controlled substance.
Pearl was arrested for possession of a stolen vehicle and for committing a felony while out on bail, Brooks said.
Both were transported to the Lake County Hill Road Correctional Facility and booked on the charges. Booking records showed Labrash was held on $20,000 bail, with Pearl's bail set at $15,000.
Labrash remained in custody early Saturday, while Pearl had posted the required portion of bail and been released, based on jail records.
LAKE COUNTY, Calif. – A 3.4-magnitude earthquake shook The Geysers geothermal steamfield early Friday.
The quake occurred at 5:05 a.m., according to the US Geological Survey.
It was centered six miles west northwest of The Geysers, 15 miles southwest of Clearlake and 14 miles north of Healdsburg, at a depth of 1.4 miles.
The US Geological Survey received six shake reports from five zip codes, including Lakeport, Cloverdale, Sacramento, San Mateo and even as far away as Scotts Valley in Santa Cruz County.
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LAKEPORT, Calif. – The Lakeport Police Department said a young Lakeport man has been arrested on charges including child concealment and contributing to the delinquency of a minor in connection to the case of a runaway teenage girl found safe on Friday afternoon.
Police said Robert Andres Juarez-Karns, 21, was taken into custody after officers found 15-year-old Halle Miller of Lakeport at his residence.
The teen had gone missing Thursday evening, with police asking for the community's help in locating her on Friday.
The Lakeport Police Department reported that at 2:30 p.m. Friday officers developed a lead from a business in the city of Lakeport which led them to a residence in the 600 block of N. Forbes Street.
Upon arrival, officers were advised by Juarez-Karns that the girl was not in the residence. However, police said the officers conducted a search of the residence and located her.
Police said Juarez-Karns was arrested for felony child concealment and misdemeanor charges of contributing to a minor and resisting/delaying/or obstructing peace officers in the performance of their duty.
Juarez-Karns was transported to the Lake County Correctional Facility where he was booked. Jail records indicated his bail was set at $35,000.
Police said the investigation is ongoing.
The agency thanked the members of the public who provided numerous leads to assist in locating Halle Miller.
LAKEPORT, Calif. – The Lakeport Police Department said Friday afternoon that a missing Lakeport teen has been found.
Halle Miller, 15, had been missing since 5:30 p.m. Thursday from her residence on Forrest Drive, as Lake County News has reported.
Police said the girl was safe.