Centaurs are minor planets believed to have originated in the Kuiper Belt in the outer solar system. They sometimes have comet-like features such as tails and comae—clouds of dust particles and gas—even though they orbit in a region between Jupiter and Neptune where it is too cold for water to readily sublimate, or transition, directly from a solid to a gas.
Only 18 active Centaurs have been discovered since 1927, and much about them is still poorly understood. Discovering activity on Centaurs is also observationally challenging because they are faint, telescope time-intensive and because they are rare.
A team of astronomers, led by doctoral student and Presidential Fellow Colin Chandler in Northern Arizona University’s Astronomy and Planetary Science PhD program, earlier this year announced their discovery of activity emanating from Centaur 2014 OG392, a planetary object first found in 2014. They published their findings in a paper in The Astrophysical Journal Letters, “Cometary Activity Discovered on a Distant Centaur: A Nonaqueous Sublimation Mechanism.” Chandler is the lead author, working with four NAU co-authors: graduate student Jay Kueny, associate professor Chad Trujillo, professor David Trilling and Ph.D. student William Oldroyd.
The team’s research involved developing a database search algorithm to locate archival images of the Centaur as well as a follow-up observational campaign.
“Our paper reports the discovery of activity emanating from Centaur 2014 OG392, based on archival images we uncovered, plus our own new observational evidence acquired with the Dark Energy Camera at the Inter-American Observatory in Cerro Tololo, Chile, the Walter Baade Telescope at the Las Campanas Observatory in Chile and the Large Monolithic Imager at Lowell Observatory’s Discovery Channel Telescope in Happy Jack, Arizona,” Chandler said.
“We detected a coma as far as 400,000 km from 2014 OG392 and our analysis of sublimation processes and dynamical lifetime suggest carbon dioxide and/or ammonia are the most likely candidates for causing activity on this and other active Centaurs. We developed a novel technique that combines observational measurements, for example, color and dust mass, with modeling efforts to estimate such characteristics as the object’s volatile sublimation and orbital dynamics.”
As a result of the team’s discovery, the Centaur has recently been reclassified as a comet, and will be known as “C/2014 OG392 (PANSTARRS).”
“I’m very excited that the Minor Planet Center awarded a new comet designation befitting the activity we discovered on this unusual object,” he said.
This week, Chandler has been invited to present the results at the 52nd Division for Planetary Sciences (DPS) of the American Astronomical Society (AAS) 2020 meeting.
Reference: “Cometary Activity Discovered on a Distant Centaur: A Nonaqueous Sublimation Mechanism” by Colin Orion Chandler, Jay K. Kueny, Chadwick A. Trujillo, David E. Trilling and William J. Oldroyd, 6 April 2020, The Astrophysical Journal Letters.
Chandler’s research is funded by Grant No. 2018258765 through the National Science Foundation’s Graduate Research Fellowship Program (GRFP), a highly competitive opportunity that only about 2,000 students receive each year.
China's Chang'e-5 probe enters lunar orbit – ecns
China’s Chang’e-5 probe decelerated and entered the lunar orbit on Saturday, completing a vital step on its way to collect and return moon samples, the China National Space Administration (CNSA) announced.
After flying about 112 hours from Earth, an engine on the probe ignited when it was 400 km away from the surface of the moon at 8:58 p.m. and shut down after about 17 minutes, the CNSA said.
The probe performed the braking without incident and entered the lunar orbit successfully, according to the real-time monitoring data.
Chang’e-5, comprising an orbiter, a lander, an ascender, and a returner, has carried out two orbital corrections during the Earth-Moon transfer, achieving its expected goals.
Afterward, it will adjust the altitude and inclination of its orbit around the moon. When the time is appropriate, the lander-ascender combination will separate from the orbiter-returner combination, implement a soft landing on the near side of the moon, and carry out automatic sampling as planned.
China's lunar probe Chang'e-5 enters lunar orbit after perilune braking – CGTN
China’s Chang’e-5 probe decelerated and entered lunar orbit on Saturday, completing a vital step on its way to collect and return moon samples, the China National Space Administration (CNSA) announced.
The probe performed the braking at perilune without incident and entered the lunar orbit successfully, according to real-time monitoring data. Braking at perilune is a critical maneuver, as the probe, traveling at a high speed, needs to carry out braking to lower its relative velocity, to enable it to be captured by lunar gravity.
This is how you can really help reduce greenhouse gas emissions – CTV News
When many Canadians think of how they can help lower greenhouse gas emissions, they often look for ways to reduce their own carbon footprint by flying less frequently or driving an electric vehicle, for example.
However, as laudable as those actions may be, climate activists say there are more effective ways for people to become involved and make a difference.
Alex Speers-Roesch, a climate campaigner with Greenpeace Canada, explained that the phrase “carbon footprint,” which is the measure of the total greenhouse gas emissions directly or indirectly caused by an individual, organization, event, or product, was actually popularized by the multinational oil and gas company BP in the early 2000s in an attempt to put the burden of change on to the individual.
“It’s good for people to think about the emissions associated with the things that they consume, but there’s a tendency sometimes in the way that carbon footprints are talked about and promoted that tries to put the onus on individuals and consumers for those emissions in a way that can be unfair,” he told CTVNews.ca during a telephone interview in late November.
Lauren Latour, a climate ambition co-ordinator for Climate Action Network Canada, cited a study from a few years ago that showed that just 100 companies were responsible for 70 per cent of the world’s greenhouse gas emissions since 1988.
She also referenced another recent study that claimed frequent-flying “super emitters,” consisting of just 1 per cent of the population, were responsible for half of the world’s aviation carbon emissions in 2018.
“The average Canadian is very much not responsible for the lion’s share of harmful climate change effects,” Latour said during an interview with CTVNews.ca in late November.
So while both Latour and Speers-Roesch said Canadians should be mindful of the greenhouse gas emissions associated with the goods and services they consume and how their individual choices affect the environment, they said there are other, more impactful, ways for them to address the climate emergency.
“It’s not going to be the individual actions of consumers that are going to address the climate crisis, what we really need is collective action from all of us working together to produce systemic change,” Speers-Roesch said.
Canadians interested in doing their part to reduce global greenhouse gas emissions can start by seeking out more information about the topic from environmental organizations dedicated to the cause, Speers-Roesch suggested.
He said there are many climate change groups operating in Canada, such as Greenpeace Canada, 350 Canada, Environmental Defence, and Climate Action Network Canada.
“Find a group like that, sign up for the email list, see if you can get involved,” he said. “Once you start looking, though, you start to see, ‘Oh there are opportunities everywhere.’”
Speers-Roesch said Canadians can also seek out climate change events happening in their area. For example, if there is a protest nearby, he suggested going to see what it’s about and to meet other attendees.
“As you connect with others and get more involved and get more engaged, you’ll probably have more ideas,” he said. “Before you know it, you’ll have lots of stuff to keep you busy on climate change.”
BECOME POLITICALLY ENGAGED
Latour acknowledged that getting involved in politics can be a “scary” thing for a lot of people, but that it doesn’t have to be and there are many opportunities to become engaged by joining community-led initiatives.
She said Canadians can join local organizations that work to influence government policy on the municipal level.
“For instance, a city is able to switch its bus fleet over from fuel combustion buses to low emissions, or hybrid or electric buses, or an electric light rail system,” she said.
Latour said Canadians can also volunteer for a mutual aid effort that is dedicated to building resiliency in their town or region. For example, she cited the groups that stepped up to help mitigate the effects of flooding in the Ottawa area over the past few years.
“In a lot of places, we see municipalities and we see smaller communities really leading the way on climate change and on climate policy,” she said.
“Individual change does matter and that individual change is getting involved in community organizing and getting involved in influencing your politics and local legislation.”
Speers-Roesch, too, said political activism is one of the most important things Canadians can do to become involved in the fight against climate change.
“The majority of the emissions are due to industry and are a result of government policy decisions so that’s really the most important and impactful place that people can focus their energies,” he said.
The Greenpeace campaigner said that Canadians should learn about their local politicians’ environmental platforms and encourage them to act.
“Call your MP, call your MPP, or city councillor,” he said. “Let them know you want them to do more on climate change.”
PUSH THE CONVERSATION FORWARD
Finally, Speers-Roesch said Canadians can still do their part by incorporating climate change issues and pushing the conversation forward in their daily lives.
“Think about how you can bring climate activism into your existing life,” he said. “It doesn’t always necessarily have to be finding another group and joining them.”
As an example, Speers-Roesch said someone who is already part of a book club that meets on a weekly basis could suggest a book for them to read on climate change.
He said they could also organize an event within an organization they’re already involved in, such as their workplace, school, sports team, church, or temple, to raise more awareness.
“Look for a little thing that you can do each week to sort of make your voice heard and get activated and engaged on climate change,” Speers-Roesch advised. “Climate change is something that we really need to sort of infuse into every aspect of our lives and our work and everything that we do.”
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