Saturday, December 7, 2013

Subaru Telescope Captures the Fine Details of Comet Lovejoy’s Tail

Comet ISON may be no more than just a cloud of icy debris these days but there’s another comet that’s showing off in the morning sky: C/2013 R1 (Lovejoy), which was discovered in September and is steadily nearing its Christmas Day perihelion. In the early hours of Dec. 3, astronomers using the 8.2-meter Subaru Telescope atop Mauna Kea in Hawaii captured this amazing image of Lovejoy, revealing the intricate flows of ion streamers in its tail.

Courtsey - Universetoday

Comet lovejoy Path in December 2013


Comet Lovejoy during the Month of December 2013
Map Courtesy - AstroBob

THE GHOST OF COMET ISON


On the morning of Dec. 6th, leading researchers from the Comet ISON Observing Campaign (CIOC) held an informal workshop at the Johns Hopkins Applied Physics Lab. One of the key questions they discussed was, Did Comet ISON survive? It might seem surprising that anyone is still asking. After all, the "comet" that emerged from the sun's atmosphere on Thanksgiving day appeared to be little more than a disintegrating cloud of dust. This movie from the STEREO-A spacecraft (processed by Alan Watson) shows the V-shaped cloud fading into invisibility on Dec. 1st:



The answer hinges on the contents of that cloud. Is it nothing more than a cloud of dust--or could there be some some fragments of the disintegrated nucleus still intact and potentially active?

A key result announced at the workshop comes from SOHO, the Solar and Heliospheric Observatory. According to the spacecraft's SWAN instrument, the comet stopped producing so-called Lyman alpha photons soon after its closest approach to the sun. Karl Battams of the CIOC explains what this means: "Without getting technical, Lyman-Alpha is a consequence of sunlight interacting with hydrogen, and if we are not seeing that interaction then it means that the levels of hydrogen (and hence ice) are extremely low. This is indicative of a completely burned out nucleus, or no nucleus at all."

"The evidence appears strong that at some point approaching perihelion - whether days or hours - Comet ISON likely began to completely fall apart," he continues. "What remains of ISON now is going to be either just a cloud of dust, or perhaps a few very depleted chunks of nucleus. Either way, it's not going to flare up at this point and we should assume the comet's show is over."

"However, we do need to verify this," says Battams. "Hopefully the Hubble team can come to the rescue! In mid-December, Hubble will be pointed in the direction of where ISON should be and they'll try and image something. If no fragments are surviving, or they are tiny, then Hubble will not be able to find anything, but that negative detection will tell us something: namely that ISON is indeed gone for good."
Courtesy - spaceweather.com

Monday, December 2, 2013

Obituary ISON



Comet C/2012 S1 (ISON)
Born 4.5 Billion BC, Fragmented Nov 28, 2013 (age 4.5-billion yrs old)

Born in a dusty and turbulent environment, comet ISON spent its early years being jostled and struck by siblings both large and small. Surviving a particularly violent first few million years, ISON retreated to the Oort Cloud, where it maintained a largely reclusive existence for nearly four billion years. But around 3-million B.C., a chance encounter with a passing star coerced ISON into undertaking a pioneering career as a Sungrazer. On September 21, 2012, ISON made itself known to us, and allowed us to catalog the most extraordinary part of its spectacular vocational calling.

Never one to follow convention, ISON lived a dynamic and unpredictable life, alternating between periods of quiet reflection and violent outburst. However, its toughened exterior belied a complex and delicate inner working that only now we are just beginning to understand. In late 2013, Comet ISON demonstrated not only its true beauty but a surprising turn of speed as it reached its career defining moment in the inner solar system. Tragically, on November 28, 2013, ISON's tenacious ambition outweighed its ability, and our shining green candle in the solar wind began to burn out.

Survived by approximately several trillion siblings, Comet ISON leaves behind an unprecedented legacy for astronomers, and the eternal gratitude of an enthralled global audience. In ISON's memory, donations are encouraged to your local astronomy club, observatory or charity that supports STEM and science outreach programs for children.

Courtesy - Karl Battams