Comets


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Best of the Web: Surprising Comet Lovejoy Now Becoming Merry and Bright

Lovejoy_1
© kommet.czComet Lovejoy photographed remotely with the FRAM telescope in Argentina on Dec. 17 by a Czech team of Jakub Cerny, Jan Ebr, Martin Jelinek, Petr Kubanek, Michael Prouza and Michal Ringes.

It was almost a pre-holiday miracle that Comet Lovejoy survived its close encounter with the Sun on Dec. 15, 2011. But now, the feisty comet is making a 'merry and bright' comeback, re-sprouting its tail and showing up brilliantly with binoculars and in telescopic images from southern hemisphere skywatchers.

"It was a big surprise that after going through the solar atmosphere it re-emerged with a beautiful tail," Karl Battams told Universe Today. Battams is with Naval Research Laboratory and has been detailing the Comet Lovejoy's incredible journey on the Sungrazing Comets website. "And basically within a day it was as bright after the encounter as it was before."

The beautiful image above was taken on Dec. 17, 2011, clearly showing two gorgeous tails on Comet Lovejoy. See more from the Czech team that took the image at their website, Kommet.cz.

As much as this comet has surprised everyone, no one is going out on a limb and predicting it will become visible with the naked eye. But who knows? The comet's discoverer, Austrailian amateur astronomer Terry Lovejoy was able to image the comet in the day time! " I am hopeful of a nice binocular comet low in the dawn around Christmas time," Lovejoy said on the Ice in Space website.

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Update: Comet Lovejoy in the morning

Noted astronomer John Bortle urges observers (especially in the southern hemisphere) to "begin searching for Comet Lovejoy's bright tail projecting up out of the morning twilight beginning at dawn. The tails of some of the major sungrazing comets have been extraordinarily bright. Comet Lovejoy's apparition has been so bizarre up to this point that it is difficult to anticipate just what might happen next ... [including] the exact sort of tail it might unfurl in the morning sky."

UPDATE: This morning in New Zealand, Minoru Yoneto photographed the ghostly tail of Comet Lovejoy shining through the twilight:
Image
© Minoru Yoneto

"I couldn't see the comet with my naked eye, but a 1.3 sec exposure with my Canon Kiss X2 digital camera revealed Lovejoy's long tail." In the clearer skies of Devonport, Tasmania, amateur astronomer Peter Sayers did see the tail with his unaided eyes--"but just barely," he says. "The tail was just naked-eye and perhaps a degree long in our Tasmanian summer early morning twilight." [image]

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Continued Adventures of Comet Lovejoy

The scorched core of sungrazing Comet Lovejoy is still intact as it recedes from the sun. Even the comet's flamboyant tail, temporarily lost in transit through the solar corona, has regrown. Click here to view the last 24 hours of coronagraph images from the Solar and Heliospheric Observatory (SOHO).


SOHO images show two tails: the ion tail and the dust tail. The ion tail is made of gas and is blown directly away from the sun by the solar wind. The heavier dust tail is curved and more closely traces the comet's orbit.

Now that the comet is more than five degrees from the sun, it is possible (albeit still not easy) for amateur astronomers to photograph it just before sunrise. A team led by Czech astronomer Jan Ebr captured this image at sunrise on Dec. 17th:

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Comet Lovejoy Survives

Incredibly, sungrazing Comet Lovejoy appears to have survived its close encounter with the sun. Lovejoy flew only 140,000 km over the stellar surface during the early hours of Dec. 16th. Experts expected the icy sundiver to be destroyed. Instead, NASA's Solar Dynamics Observatory caught the comet emerging from perihelion (closest approach) at least partially intact:


SDO also recorded Comet Lovejoy's entry into the sun's atmosphere: movie.

Comet Lovejoy began the week as a chunk of dusty, rocky ice some 200 meters in diameter. No one can say how much of the comet's core remains intact or how long it will hang together after the searing heat of perihelion.

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Comet Lovejoy Has a Friend!

Another Comet
© Sungrazer BlogClick here to see animation.
This is too cute: Comet Lovejoy has a friend! Look in the upper-half of the animation opposite, starting at center and moving diagonally up and to the left, perfectly in step with Lovejoy... It's another Kreutz-group comet! (if you can't see it, here's a hint)

As nice as this is, I am not in the least surprised. SOHO's Kreutz-group comets are very "clumpy", for want of a better word. We frequently see them arrive in pairs or sometimes trios, and the big bright ones in particular will often have a companion comet. I suspected we would get at least one with Comet Lovejoy and indeed we do. It's much more typical of the size and brightness of Kreutz comets we see, and offers a wonderful comparison to highlight just how special Comet Lovejoy is.

So what is this new comet called? Is it another "Comet Lovejoy"? Sadly not. It looks to me like it was actually spotted in the LASCO C3 images by seasoned comet hunter Zhijian Xu at Dec 14 2011 11:48:48. So will it be Comet Xu?? No again. It will be Comet SOHO, number 2190-something, I think. Oh, and notice how it's orbit is obviously slightly different from Lovejoy's? That's also something we see all the time; the companion comets are frequently in slightly different orbits. They are obviously closely related though and the smaller one must have fragmented from Lovejoy some significant time ago, and with some slight (non-gravitational) force between them to "push" them apart like this. These kinds of break-ups are theorized to happen decades before they reach the Sun in order for them to have this kind of separation in space, though this process is not well-known or well-understood at all. It one reason that studying these Kreutz comets is so important, as this knowledge can be applied to all comets and solar system bodies, and give a broader understanding of their orbital and physical evolution.

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Comet Lovejoy update - will it miss the sun?


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Significant Comet Plunges in the Sun

A comet nearly as wide as two football fields (200m) is plunging toward the sun where it will most likely be destroyed in a spectacular light show on Dec. 15/16. Although Comet Lovejoy (C/2011 W3) could become as bright as Jupiter or Venus when it "flames out," the glare of the sun will hide the event from human eyes. Solar observatories in space, however, will have a grand view. Yesterday the brightening comet entered the field of view of NASA's STEREO-B spacecraft.


"You can clearly see the comet heading diagonally through the images," says Karl Battams of the Naval Research Lab who prepared the animation. "During the 16-hour sequence, the comet brightens from magnitude +8 to +6.5, approximately."

It will soon grow much brighter. "This comet is a true sungrazer, and will skim approximately 140,000 km (1.2 solar radii) above the solar surface on Dec. 15/16," notes Battams. At such close range, solar heating will almost certainly destroy the icy interloper,creating a cloud of vapor and comet dust that will reflect lots of sunlight. The Solar and Heliospheric Observatory (SOHO) will have a particularly good view.

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Newfound Comet to Dive Through Sun Next Week

Image
© UnknownIllustration only
A newly discovered comet is racing toward a mid-December rendezvous with the sun - a rendezvous that it will likely not survive.

The comet is categorized by astronomers as a "sungrazer" and it is destined to do just that; literally graze the surface of the sun (called the photosphere) and pass through the sun's intensely hot corona, where temperatures have been measured at upwards of 3.6-million degrees Fahrenheit (2-million degrees Celsius).

While the comet will not collide with the sun, most astronomers say the odds are rather long that it will remain intact after its closest pass by the sun. The most exciting aspect of the event is that the comet's expected destruction should be visible on your computer monitor.

And there is a very slight chance that, should the comet somehow manage to survive, it might briefly become visible in broad daylight.

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The Great "Birthday Comet" of 2011

Comet Lovejoy
© SOHO

SOHO's 16th Birthday gift is on it's way, and the tracking number states delivery by midnight on December 15th!

On December 2nd, 2011, newly discovered Kreutz-group comet C/2011 W3 (Lovejoy) was announced. SOHO discovers these objects on average every three days, but this one is different... it was found from a ground based telescope, and marks the first such discovery in over 40yrs. It also marks a significant achievement for Australian astronomer Terry Lovejoy, who as an early pioneer of discovering SOHO comets over the internet, can now claim to be the first person to discover a Sungrazer from both ground and space-based telescopes!

Traditionally, and with little exception, ground-discovered Kreutz-group comets have gotten bright. Very bright! In 1965, Kreutz-comet Ikeya-Seki was so bright, it could be seen by the naked eye by blocking the Sun out with your hand. We do not expect C/2011 W3 to get this bright, so reserve your seat next to your computer and stay tuned to the SOHO, STEREO and Sungrazer websites as we prepare for this rare and potentially spectacular object to enter our cameras around Dec 12, meeting its fiery demise late on Dec 15.

We will have more information on this site over the coming week. In the meantime, updates will occasionally be posted at the Sungrazer site.

Stay tuned!

Question

Did Comet Killing Spark Christmas Light Show?

Neutron Star
© Aurore Simonnet, NASA E/PO, Sonoma State UniversityAn artist’s impression of a neutron star consuming a comet and unleashing a gamma-ray burst in the process.

Object type: Gamma-ray burst

Constellation: Andromeda

The timing could hardly have been more auspicious. Like a 2000-year-old gamma-ray echo of the biblical star of Bethlehem, on Christmas day 2010 an unprecedented tussle broke out in the heavens.

It sent a flood of high-energy radiation towards Earth that lasted much longer than is typical for a gamma-ray burst (GRB). Now it seems the peculiar event clashes with the leading theory for how such blasts of radiation form, and may instead involve the grisly demise of a comet.

At 18:37 GMT on 25 December 2010, the spectacular light show erupted, though you would have needed gamma-ray eyes to see it. Researchers did the next best thing, watching it with instruments on NASA's Swift satellite.

Gamma-rays are extremely energetic photons and it takes a very violent event to produce them in large quantities. Hundreds of GRBs flash on and off in the sky like fireflies each year. Satellites designed to detect nuclear bomb blasts first noticed them in the late 1960s and the Swift satellite was launched in 2004 to study them in greater detail.