In Conversation With The Sun: Parker Solar Probe Communications

NASA's Swift Mission Maps a Star's 'Death Spiral' into a Black Hole

NASA - Swift Mission patch. March 20, 2017 Some 290 million years ago, a star much like the sun wandered too close to the central black hole of its galaxy. Intense tides tore the star apart, which produced an eruption of optical, ultraviolet and X-ray light that first reached Earth in 2014. Now, a team of scientists using observations from NASA’s Swift satellite have mapped out how and where these different wavelengths were produced in the event, named ASASSN-14li, as the shattered star’s debris circled the black hole. “We discovered brightness changes in X-rays that occurred about a month after similar changes were observed in visible and UV light,” said Dheeraj Pasham, an astrophysicist at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, and the lead researcher of the study. “We think this means the optical and UV emission arose far from the black hole, where elliptical streams of orbiting matter crashed into each other.”

Swift Charts a Star’s ‘Death Spiral’ into Black Hole

Video above: This animation illustrates how debris from a tidally disrupted star collides with itself, creating shock waves that emit ultraviolet and optical light far from the black hole. According to Swift observations of ASASSN-14li, these clumps took about a month to fall back to the black hole, where they produced changes in the X-ray emission that correlated with the earlier UV and optical changes. Video Credits: NASA’s Goddard Space Flight Center. Astronomers think ASASSN-14li was produced when a sun-like star wandered too close to a 3-million-solar-mass black hole similar to the one at the center of our own galaxy. For comparison, the event horizon of a black hole like this is about 13 times bigger than the sun, and the accretion disk formed by the disrupted star could extend to more than twice Earth’s distance from the sun. When a star passes too close to a black hole with 10,000 or more times the sun’s mass, tidal forces outstrip the star’s own gravity, converting the star into a stream of debris. Astronomers call this a tidal disruption event. Matter falling toward a black hole collects into a spinning accretion disk, where it becomes compressed and heated before eventually spilling over the black hole’s event horizon, the point beyond which nothing can escape and astronomers cannot observe. Tidal disruption flares carry important information about how this debris initially settles into an accretion disk. Astronomers know the X-ray emission in these flares arises very close to the black hole. But the location of optical and UV light was unclear, even puzzling. In some of the best-studied events, this emission seems to be located much farther than where the black hole’s tides could shatter the star. Additionally, the gas emitting the light seemed to remain at steady temperatures for much longer than expected. ASASSN-14li was discovered Nov. 22, 2014, in images obtained by the All Sky Automated Survey for SuperNovae (ASASSN), which includes robotic telescopes in Hawaii and Chile. Follow-up observations with Swift’s X-ray and Ultraviolet/Optical telescopes began eight days later and continued every few days for the next nine months. The researchers supplemented later Swift observations with optical data from the Las Cumbres Observatory headquartered in Goleta, California.

Image above: This artist’s rendering shows the tidal disruption event named ASASSN-14li, where a star wandering too close to a 3-million-solar-mass black hole was torn apart. The debris gathered into an accretion disk around the black hole. New data from NASA’s Swift satellite show that the initial formation of the disk was shaped by interactions among incoming and outgoing streams of tidal debris. Image Credit: NASA’s Goddard Space Flight Center.  In a paper describing the results published March 15 in The Astrophysical Journal Letters, Pasham, Cenko and their colleagues show how interactions among the infalling debris could create the observed optical and UV emission. Tidal debris initially falls toward the black hole but overshoots, arcing back out along elliptical orbits and eventually colliding with the incoming stream. “Returning clumps of debris strike the incoming stream, which results in shock waves that emit visible and ultraviolet light,” said Goddard’s Bradley Cenko, the acting Swift principal investigator and a member of the science team. “As these clumps fall down to the black hole, they also modulate the X-ray emission there.”

Swift spacecraft. Image Credit: NASA

Future observations of other tidal disruption events will be needed to further clarify the origin of optical and ultraviolet light. Goddard manages the Swift mission in collaboration with Pennsylvania State University in University Park, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan. Related: Scientists Identify a Black Hole Choking on Stardust (MIT): http://news.mit.edu/2017/black-hole-choking-stardust-0315 ASASSN-14li: Destroyed Star Rains onto Black Hole, Winds Blow it Back: http://chandra.harvard.edu/photo/2015/tidal/ 'Cry’ of a Shredded Star Heralds a New Era for Testing Relativity: https://www.nasa.gov/mission_pages/swift/bursts/shredded-star.html Researchers Detail How a Distant Black Hole Devoured a Star: https://www.nasa.gov/mission_pages/swift/bursts/devoured-star.html All Sky Automated Survey for SuperNovae (ASASSN): http://www.astronomy.ohio-state.edu/~assassin/index.shtml Las Cumbres Observatory: https://lco.global/ NASA’s Swift: http://www.nasa.gov/mission_pages/swift/main/index.html Images (mentioned), Video (mentioned), Text, Credits: NASA’s Goddard Space Flight Center, by Francis Reddy/Karl Hille. Greetings, Orbiter.ch Full article

Ep. 29 Unusual Scales - HD and the Void

From Bortle to Torino, from asteroids to aliens, scientists have been working to classify experiences in a useful way. Some of those experiences are very specific, unusual, speculative, or just bizarre. Hear about a selection of scales currently i...

I’m back with the last episode of 2018! A conversation with a friend sparked this idea and I just ran with it while I had the inspiration, so please enjoy an episode on the strange and wonderful scales that astronomers have created to quantify data that is very unusual. 

Below the cut are the glossary, transcript, sources, and music credits. Send me any topic suggestions via Tumblr message (you don’t need an account for it!). You can also tweet at me on Twitter at @HDandtheVoid, or you can ask me to my face if you know me. Subscribe on iTunes to get the new episodes of my ideally-monthly-updated podcast (I hope I have more inspiration/time in 2019), and please please please rate and review it. Go ahead and tell friends if you think they’d like to hear it, too!

(My thoughts on the next episode are the Coriolus Force, Stephen Hawking, or famous comets. The next episode will go up in 2019, hopefully in early January!)

Glossary

background risk - the average risk from random impacts of space objects with Earth.

Bortle Scale - an objective scale to measure the clarity and effect of light pollution on a night’s stargazing.

Drake Equation - a way to estimate the number of potential active, communicative civilizations in the Milky Way galaxy based on 1) the average rate of star formation in our galaxy 2) the fraction of those stars that have planets 3) the average number of planets that can potentially support life per star with its own orbiting planets 4) the fraction of planets that could support life which actually develop life at some point 5) the fraction of planets with life that actually go on to develop intelligent life and civilizations 6) the fraction of civilizations that develop a technology that releases detectable signs of their existence into space 7) the length of time it would take those civilizations release detectable signals into space.

Hynek Scale - quantifies encounters with UFOs and aliens.

Kardashev Scale - measures how advanced a civilization’s technology is based on their mastery of resources and exploration into space.

METI - Messaging to ExtraTerrestrial Intelligence

Palermo Technical Impact Hazard Scale - categorizes and prioritizes the potential impact risks of objects in space, such as asteroids.

Rio Scale - quantifies the impact of any public announcement regarding evidence of extraterrestrial intelligence.

San Marino Scale - quantifies the impact of sending transmissions from Earth to extraterrestrial intelligence.

SETI - the Search for ExtraTerrestrial Intelligence.

Torino Scale - communicates the risk associated with a particular asteroid or comet’s potential to impact with Earth to the public.

Script/Transcript

Sources

10 Unusual Scientific Scales via Listverse (Sep 2010)

John Bortle’s article on his magnitude scale via Sky and Telescope, July 2006

“I have created a nine-level scale. It is based on nearly 50 years of observing experience. I hope it will prove both enlightening and useful to observers — though it may stun or even horrify some! Should it come into wide use, it would provide a consistent standard for comparing observations with light pollution.”

Bortle dark sky scale via Big Sky Astronomy Club

Bortle dark sky scale via LSU

Palermo Technical Impact Hazard Scale via NASA

The Palermo Scale is the base-10 logarithm of the relative risk.

PS = log10 R.

The relative risk R is given by R = PI / (fB × DT), where PI is the impact probability of the event in question and DT is the time until the potential event, measured in years. 

The annual background impact frequency, fB = 0.03 × E-4/5, is the annual probability of an impact event with energy (E, in megatons of TNT) at least as large as the event in question.

Torino Impact Hazard Scale via NASA

Rio Scale via SETI League

San Marino Scale via SETI League

Rio and San Marino Scale history via Wikipedia

Drake Equation via Wikipedia

Nikolai Kardashev via Wikipedia

"energy consumption at ≈4×1019 erg/sec (4 × 1012 watts)."

New Variation of Kardashev Scale Developed via Edgy Labs (June 2018)

J. Allen Hynek's Scale Of UFO Classification via The Night Sky

Hynek's UFO Classification System via The Center for UFO Studies

Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity

Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught

Astronaut tweets

Of Course I Still Love You returned to Port Canaveral earlier this morning with the SES-10 Falcon 9 first stage. Since this is the first Falcon 9 rocket to be reflown this marks the second time this particular rocket returned to port after landing. The images above were captured by remote cameras on the droneship and show the vehicle coming into land. Falcon 9 landed eight minutes after a March 30 liftoff from LC-39A at Kennedy Space Center. Extensive scorching is visible on the exterior of the rocket including the interstage and grid fins. The fins themselves were seen glowing during launch footage as the booster returned to Earth. Each fin is coated in ablative paint which helps protect the metal but the severe temperatures of reentry still cause the fins to glow. Since SES-10 was placed into Geostationary Transfer Orbit, not enough propellant remained in the first stage’s tanks to allow for a nominal reentry profile and the boostback burn was not performed. As such, the rocket came in over twice its normal landing speed and eight times hotter than flights which have a boostback burn. This particular rocket will not be reused after recovery; Elon Musk stated in the SES-10 post-launch news conference that the rocket will likely be given to the Air Force for display at either Cape Canaveral or Kennedy Space Center. P/C: SpaceX

Aboard the International Space Station, astronaut Thomas Pesquet of the European Space Agency snapped this photo and wrote, ‘The view at night recently has been simply magnificent: few clouds, intense #aurora. I can’t look away from the windows.' 

The dancing lights of the aurora provide stunning views, but also capture the imagination of scientists who study incoming energy and particles from the sun. Aurora are one effect of such energetic particles, which can speed out from the sun both in a steady stream called the solar wind and due to giant eruptions known as coronal mass ejections or CMEs. Credit: NASA/ESA

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Mosaic of the nebulae in the Orion Constellation

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27 of Hubble's Best Photos for Its 27th Birthday

Hubble turns 27 today. Here's a look back at some of its most noteworthy accomplishments.

You may recognize the seventh picture in the slideshow--it’s my profile picture here. Happy birthday Hubble, you’re older than I am!

Ep. 13 Lunar and Solar Orbits - HD and the Void

This is a short one but I do explain concepts you can see and track yourself over the months with very little effort. The shapes of the Moon and how long it takes different planets to orbit the Sun! Time is a human construct! Tidal forces and the ...

Why do the Sun and Moon move the way they do? What’s up with that? Orbits? What? It’s a short but snug little episode here about the Sun and the Moon and how they look from Earth as they zoom across the sky.

Below the cut are my sources, music credits, a vocab list, the transcript of this episode, a composite image of the different phases of the Moon, and a list of the different names for the full moons through the course of a year. Let me know what you think I should research next by messaging me here, tweeting at me at @HDandtheVoid, or asking me to my face if you know me in real life. And please subscribe to  the podcast on iTunes, rate it or review it, and maybe tell your friends about it if you think they’d like to listen!

(My thoughts on the next episode, because I still haven’t found the time to cover them, are the Voyager golden records, space race history, the transit of Venus, the Moon landing, or Edmond Halley. Let me know by the 6th and I’ll hopefully have the next podcast up on October 16th.)

Glossary

blue moon - when you get two full moons in one calendar month. An older definition is when you get 4 full moons in a season, the third moon is called the ‘blue moon.’

ecliptic - the path of the Sun over the course of a year.

prograde - when a planet spins from east to west. 

retrograde - when a planet spins from west to east.

spaghettification - when extreme tidal forces pull an object apart in space.

Script/Transcript

Sources

Rising and setting times of the Sun on Earth via Cornell University

Seasons on Earth via Cornell University

Lunar phases and the Moon’s relationship to the Sun via Harvard

Tides via Hyperphysics

Tidal forces equation via AstronomyOnline.org

Tidal forces and spaghettification via NASA handout

Lunar phases composite via Fred Espenak

Names of the different full moons throughout the year via EarthSky.org

Blue moons via EarthSky.org

Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity

Filler Music: ‘See The Constellation’ by They Might Be Giants off their album Apollo 18

Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught

Opportunity discovers fresh crater on Mars

via reddit

A Young star rebels against its parent cloud

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