เหตุการณ์ใน-นอกโลก VS ภัยธรรมชาติ และupdate พายุสุริยะ

TWO COMETS AND THE SOUTHERN LIGHTS: Two comets are now visible in the skies of the southern hemisphere: "Comet Lemmon and Comet PanSTARRS got close enough together on the morning of Feb. 17th to fit into single image with a 35mm lens," reports Alex Cherney of Flinders, Victoria, Australia. "A brief but reasonably strong aurora was a welcome bonus." Click to set the scene in motion:



"Both comets were faint but visible to the naked eye, C/2011 L4 (PanSTARRS) slightly brighter than C/2012 F6 (Lemmon)," says Cherney. "I would guestimate the visual magnitude of Comet Lemmon at +5.5 and PanSTARRS at +5." Also visible in Cherney's images are the Small Magellanic Cloud and the 47 Tuc globular star cluster.

Comet Pan-STARRS is heading for a close encounter with the sun just inside the orbit of Mercury that could significantly boost its visibility in early March. At that time, the comet will be visible to northern-hemisphere observers as well. A video from NASA explores the possibilities.

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ดาวหางสองดวงตอนนี้สามารถเห็นได้ด้วยตาเปล่าที่ทางโลกซีกใต้ "ดาวหาง Lemmon และ ดาวหาง PanSTARRS อยู่ใกล้กันพอที่จะเห็นพร้อมๆ กันเมื่อวันที่ 17 กุมภาพันธ์ ในภาพเดียวกันด้วยเลนส์ 35 mm" Alex Cherney ที่ Flinders วิคตอเรีย ออสเตรเลีย รายงานไว้ "สั้นๆ แต่ ออโรร่าที่เห็นได้ชัดได้ ถูกรับเชิญมาเป็นโบนัส"

ดาวหางทั้งสองไม่ได้ชัดมากแต่สามารถมองเห็นได้โดยตาเปล่า C/2011 L4 (PanSTARRS) จะสว่างมากกว่า C/2012 F6 (Lemmon) เล็กน้อย Cherney กล่าวไว้ "ผมเดาว่าดาวหาง Lemmon จะเห็นได้ด้วยความสว่าง +5"

ดาวหาง Pan-STARRS กำลังหันหนัามุ่งไปใกล้กับดวงอาทิตย์กำลังเข้าไปในวงโคจรของดาวพุธ นั่นหมายความว่ามันสามารถเพิ่มความสว่างและทำให้เห็นได้ชัดได้ในเดือนมีนาคม ถึงเวลานั้นดาวหางนี้จะเห็นได้ในซีกโลกทางเหนือด้วย

 

Fermi proves supernova remnants produce cosmic rays
A new study reveals the first clear-cut evidence that the expanding debris of exploded stars produces some of the fastest-moving matter in the universe.

By NASA Headquarters, Washington, D.C., NASA's Goddard Space Flight Center, Greenbelt, Maryland — Published: February 15, 2013


The W44 supernova remnant is nestled within and interacting with the molecular cloud that formed its parent star. Fermi's LAT detects GeV gamma rays (magenta) produced when the gas is bombarded by cosmic rays, primarily protons. Radio observations (yellow) from the Karl G. Jansky Very Large Array near Socorro, N.M., and infrared (red) data from NASA's Spitzer Space Telescope reveal filamentary structures in the remnant's shell. Blue shows X-ray emission mapped by the Germany-led ROSAT mission. // NASA/DOE/Fermi LAT Collaboration, NRAO/AUI, JPL-Caltech, ROSAT

A new study using observations from NASA’s Fermi Gamma-ray Space Telescope reveals the first clear-cut evidence that the expanding debris of exploded stars produces some of the fastest-moving matter in the universe. This discovery is a major step toward understanding the origin of cosmic rays, one of Fermi’s primary mission goals.

“Scientists have been trying to find the sources of high-energy cosmic rays since their discovery a century ago,” said Elizabeth Hays from NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Now, we have conclusive proof supernova remnants, long the prime suspects, really do accelerate cosmic rays to incredible speeds.”

Cosmic rays are subatomic particles that move through space at almost the speed of light. About 90 percent of them are protons, with the remainder consisting of electrons and atomic nuclei. In their journey across the galaxy, the electrically charged particles are deflected by magnetic fields. This scrambles their paths and makes it impossible to trace their origins directly.

Through a variety of mechanisms, these speedy particles can lead to the emission of gamma rays, the most powerful form of light and a signal that travels to us directly from its sources.

Since its launch in 2008, Fermi’s Large Area Telescope (LAT) has mapped million- to billion-electron-volt (MeV to GeV) gamma rays from supernova remnants. For comparison, the energy of visible light is between 2 and 3 electron volts.

The Fermi results concern two particular supernova remnants, known as IC 443 and W44, which scientists studied to prove supernova remnants produce cosmic rays. IC 443 and W44 are expanding into cold dense clouds of interstellar gas. These clouds emit gamma rays when struck by high-speed particles escaping the remnants.

Scientists previously could not determine which atomic particles are responsible for emissions from the interstellar gas clouds because cosmic-ray protons and electrons give rise to gamma rays with similar energies. After analyzing four years of data, Fermi scientists see a distinguishable feature in the gamma-ray emission of both remnants. The feature is caused by a short-lived particle called a neutral pion, which is produced when cosmic-ray protons smash into normal protons. The pion quickly decays into a pair of gamma rays, emission that exhibits a swift and characteristic decline at lower energies. The low-end cutoff acts as a fingerprint, providing clear proof that the culprits in IC 443 and W44 are protons.

“The discovery is the smoking gun that these two supernova remnants are producing accelerated protons,” said Stefan Funk from the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University in California. “Now we can work to better understand how they manage this feat and determine if the process is common to all remnants where we see gamma-ray emission.”

In 1949, the Fermi telescope’s namesake, physicist Enrico Fermi, suggested the highest-energy cosmic rays were accelerated in the magnetic fields of interstellar gas clouds. In the decades that followed, astronomers showed supernova remnants were the galaxy’s best candidate sites for this process.

A charged particle trapped in a supernova remnant’s magnetic field moves randomly throughout the field and occasionally crosses through the explosion’s leading shock wave. Each round trip through the shock ramps up the particle’s speed by about 1 percent. After many crossings, the particle obtains enough energy to break free and escape into the galaxy as a newborn cosmic ray.

The supernova remnant IC 443, popularly known as the Jellyfish Nebula, is located 5,000 light-years away toward the constellation Gemini and is thought to be about 10,000 years old. W44 lies about 9,500 light-years away toward the constellation Aquila and is estimated to be 20,000 years old. Each is the expanding shock wave and debris formed when a massive star exploded.

NASA | Fermi Proves Supernova Remnants Produce Cosmic Rays - YouTube

The husks of exploded stars give rise to some of the fastest particles in the cosmos. New findings by NASA's Fermi show that two supernova remnants accelerate protons to near the speed of light. These protons interact with nearby interstellar gas clouds, which then emit gamma rays. // NASA's Goddard Space Flight Center

 

จุดดับลดลงอย่างฉับพลัน...

 

FARSIDE CME: There is an active sunspot on the farside of the sun. Yesterday, Feb. 25th, it blasted a coronal mass ejection (CME) over the sun's northwestern limb, shown here in a movie from the Solar and Heliospheric Observatory:

CME ด้านตรงกันข้ามกับโลก: มีจุดดับอันหนึ่งซึ่งอยู่ที่ดวงอาทิตย์ด้านตรงกันข้ามกับโลกกำลังปะทุ เมื่อวานนี้ 25 กุมภา ได้ระเบิดและเกิด CME มาทางด้านตะวันตกเฉียงเหนือของดวงอาทิตย์ ดังรูปที่แสดงอยู่ด้านล่าง





A 3D model of the CME prepared by analysts at the Goddard Space Weather Lab shows that the CME will miss everything--no planets are in the line of fire.

NASA's STEREO-Ahead spacecraft is stationed over the farside of the sun, almost directly above the CME. Images from the spacecraft pinpointed the source of the blast: It is active sunspot AR1678, which rotated off the Earthside of the sun just a few days ago.

จุดดับที่ว่านี้คือ จุดดับ 1678 ที่พึ่งจะหมุนออกจากการหันหน้าเข้าโลกเมื่อไม่กี่วันนี้เอง

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CORONAL HOLE: A dark gap in the sun's atmosphere--a "coronal hole"--has opened up, and it is spewing a stream of solar wind into space. NASA's Solar Dynamics Observatory (SDO) photographed the opening during the early hours of Feb 24th:

Coronal holes are places where the sun's magnetic field opens up and allows the solar wind to escape. A stream of solar wind flowing from this particular coronal hole is expected to reach Earth on or about March 2nd. High-latitude sky watchers should be alert for auroras on that date. Aurora alerts: text, voice.

Bonus: The image also shows the magnetic canopy of a sunspot group approaching just beyond the sun's northeastern limb. The active region should emerge in the next 24 hours.



Coroal hole: ช่องมืดๆ ในชั้นบรรยากาศของดวงอาทิตย์ - a coronal hole ได้เปิดออกมา และพ่นพายุสุริยะออกมายังอวกาศ ดาวเทียม SDO ตรวจจับได้ในเช้าวันที่ 24 กุมภาพันธ์

Coronal hole คือ ที่ๆ สนามแม่เหล็กดวงอาทิตย์ได้เปิดออกมา อนุญาตให้พายุสุริยะได้ออกมา และพายุสุริยะอันนี้ ได้ถูกคาดว่าจะมาถึงโลกเราวันที่ 2 มีนาคม คนที่คอยดูท้องฟ้าแถวขั้วโลกให้คอยดูออโรร่ากัน

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CHANCE OF EARTH-DIRECTED FLARES: Sunspot AR1682 has a 'beta-gamma' magnetic field that harbors energy for M-class solar flares. Because the sunspot is squarely facing Earth, any eruptions today would be geoeffective. NOAA forecasters estimate a 15% chance of M-flares

ความน่าจะเป็นที่เกิด flare ทิศตรงมายังโลก: จุดดับ 1682 มีชนิดสนามแม่เหล็กแบบ 'beta-gamma' และเตรียมที่จะปล่อยพลังงานแบบ M-Class flare เพราะว่าจุดดับนี้กำลังหันหน้ามายังโลกวันนี้ และอาจทำให้เกิดพายุสนามแม่เหล็กโลกอีก NOAA พยากรณ์ว่าจะมีความน่าจะเป็น 15% ที่จะเกิด M-Class flare

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JUPITER-SIZED HOLE: A magnetic filament curling around the sun's southwestern limb erupted during the early hours of Feb. 27th. As it flew away, it formed a loop of plasma big enough to pass the entire planet Jupiter. (Croquette anyone?)

หลุมเท่ากับดาวพฤหัส: filament สนามแม่เหล็กได้หลุดออกมาจากทางตะวันตกเฉียงใต้ การเหตุการณ์นี้ประมาณช่วงเช้าของวันที่ 27 กุมภาพันธ์ และพุ่งออกมา เป็นพาสม่ากลม ใหญ่พอที่จะผ่านดาวพฤหัสได้



This eruption brings to an end a stunningly beautiful prominence that amateur astronomers had been monitoring for days. Hopefully, they'll continue looking because a new prominence appears to be forming from the debris. Check the realtime gallery for new images.

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Coronal Holes: 27 Feb 13



Solar wind flowing from this coronal hole should reach Earth on March 2-3. Credit: SDO/AIA.