Comet Lovejoy: A Solar Survivor

By: J. Kelly Beatty December 16, 2011 13

Update: Exceeding all expectations, Comet Lovejoy has become a beautiful sight in predawn skies for far-southern observers — and has even been photographed from the International Space Station! Click here for details.

For two weeks, comet aficionados around the world have wondered whether an inbound iceball dubbed C/2011 W3 — Comet Lovejoy — would survive this week's close pass with the Sun. The odds weren't good: perihelion would occur just 116,000 miles (186,200 km) from the searing solar surface.

One of SOHO's coronagraphic cameras captured Comet Lovejoy (C/2011 W3) as it rounded the Sun (hidden, shown as a white ring) and reemerged after its perihelion on December 16, 2011. (The horizontal flaring of the comet's head is an artifact due to detector saturation.)

SOHO / LASCO Consortium

We all looked on as spaceborne cameras, most notably two C2 and C3 coronagraphs on the Solar and Heliospheric Observatory, kept vigil. In the days leading up to perihelion, the comet blazed in brilliance and developed a long, bright tail as it edged ever closer to the Sun.

At one point images showed a tiny fragment moving alongside the main mass. Had the comet split, or was it an undetected traveling companion? "Both — and neither," says SOHO scientist Karl Battams. He explains that it must be a piece of the parent body that fragmented long ago to create Comet Lovejoy and the thousands of other kamikaze objects known as Kreutz sungrazers.

The seemingly-doomed visitor disappeared late yesterday behind the coronagraphs' occulting masks. Perihelion came and went earlier today (at 00:30 Universal Time). Hours later, we were all stunned to see the comet reemerge from behind the opposite limb. In fact, the brilliant head could be seen on one side of the Sun, while what remained of its tail appeared on the opposite side.

In this remarkable sequence, NASA's Solar Dynamics Observatory recorded Comet Lovejoy emerging from behind the Sun's limb — and at least partially intact — on December 16, 2011.

NASA / SDO / AIA

Comet Lovejoy had survived! Clearly, it wasn't the inconsequential interloper that almost all other Kreutz sungrazers are, literally vaporizing as they near the Sun. Instead, it must be roughly 1 km across or larger to have avoided complete incineration.

"We are witnessing one of the most extraordinary events in cometary history," notes John Bortle, who has observed and studied these objects for more than 40 years. "The manner in which Comet Lovejoy is evolving is, to my knowledge, totally unique in the comet record. Its brilliant, starlike appearance this morning, when only at an extremely small heliocentric distance, harkens back once again to the reports of 'brilliant stars' being occasionally reported close to the Sun down through history."

Australian amateur Terry Lovejoy stands with the setup that he used to discover his namesake comet, C/2011 W3.

Amy Lovejoy

"I can hardly believe it!" Lovejoy told me via email. "I didn't rate it much chance of surviving to be honest, certainly not the nucleus. This exceeded all my expectations, and the perihelion coverage by all the satellites was just astounding."

Remarkably, Southern Hemisphere observers are already on the lookout for the reemergence of this celestial phoenix in the predawn sky. No one has reported success yet, suggesting that the comet's head is no brighter than magnitude 2 or 2½ (according to Bortle). But I'll wager that Terry Lovejoy is already up and getting ready to look as I write this. His discovery of C/2011 W3 on December 2nd marked the first time a sungrazing comet had been found from the ground since 1970.

Click here to check out the latest SOHO images and movies of Comet Lovejoy's remarkable passage. You'll also enjoy reading Battam's frequently updated postings about it.

Comments

Michael C. Emmert

December 16, 2011 at 12:47 pm

186,200 km from the Sun's surface is not only very hot but also there are strong tidal forces. This object was well within the Roche limit. There is no way it was a rubble pile. Shoemaker-Levy 9 didn't survive Jupiter's puny tides so this object is very different. I would guess that it's a solid chunk of iron?

This implies a differentiated parent object. If it formed in the cold outer reaches of the Solar system it would need to be about 400 km in diameter.

The Solar system gets stranger and stranger ...

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Tree of Life ©

December 17, 2011 at 12:59 am

PS. The link to JPL's Lovejoy tracker is: http://tinyurl.com/crhpngg

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Tree of Life ©

December 17, 2011 at 1:10 am

I find reason for questioning "SOHO scientist Karl Battams['s statement, which] explains that [Lovejoy's companion] must be a piece of the parent body that fragmented long ago to create Comet Lovejoy and the thousands of other kamikaze objects known as Kreutz sungrazers..."

That is, I'd like to know a little more re the exact path's of Lovejoy vs. that of Lovejoy's Companion...

As may be seen from JPL's comet tracer, the Earth is positioned very close to an ortogonal point in space relative to Lovejoy and its Companion. It follows that the relative position between the two of those comet bodies is very close to being accurately reflected by the available photograpic representations of Lovejoy and its Companion. Those photographs makes it appear as though Lovejoy and its Companion are traveling along their parallel paths side by side and without one of them being ahead of the other.

[It appears as though my prior attempts of posting this line of comment are being rejected due to being > 2000 characters...]

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Tree of Life ©

December 17, 2011 at 1:12 am

As most of us know, a planet that is more distant to the sun than another travels faster through space, and yet its angular momentum is less. That is, Jupiter's speed through space is greater than that of Mercury, yet it takes a whole lot longer for Jupiter to complete a full circle around the Sun than it does Mercury. Likewise for Lovejoy vs. its Companion...

Thus my specific questions are these:

1. Do we know whether Lovejoy's path around the Sun is inside or outside of its Companion?, and

2. Do we know more exactly whether one of those cometary bodies is ahead of the other?

Now, if the one (of those comet bodies) that is traveling along a path more distant from the Sun is ahead of the other... Yes, then I would find very strong reasons for believing Karl Battams's statement. If not, well, the more side by side their travel, without one being in front of the other, the more recent their common origin!

More at this link: http://tinyurl.com/7nn63cu

Thanks for any assistance towards finding an answer to the above questions! And, please, correct me if and where you find my reasoning being in error!

May the peace of the Creator rest over each our families and homes while we all travel along each our paths of learning and growth,

Andy ©

PS. The link to JPL's Lovejoy tracker is: http://tinyurl.com/crhpngg

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John SHeff

December 18, 2011 at 3:39 pm

Actually, part of your statement is incorrect. An object further from the Sun travels more slowly in its orbit than one closer in. Mercury, for example, averages about 48 km/sec, while Jupiter averages only 13 km/sec. - AND has farther to travel to complete an orbit.

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Graham Wolf

December 18, 2011 at 5:08 pm

What a comet... I feel sorry for Ikeya-Seki 1965f. I just xcan't seem to compete. Talk about the mosue that roared!

The SOHO vids posted by NASA a few hours ago alone are staggering... I'm totally blown away!! Even a faint ion tail as well! Terry Lovejoy and Alex Amorim have already made faint daylight observations of the comet Post Perihelion:- well done you two!

Here in Lower Hutt NZ, the Barber Grove Obvservatory (-41.22875 + 174.90300) has come off some 8 days of rain, with clear skies after local midnight (whilst out game-fishing on the Wellington Harbour). My last preperihelion observation was on Dec 09.618 UT at Mv 8.5, 0.8 arcmin, DC4. The December 10/11 Total Lunar Eclipse was clouded out all night!

Great to see Libra rise before dawn in the East this morning over the local Wainbuiomata Hills, then at dawn onset... the comet! Early this morning, the comet lay almost halfway between M7 and Mercury in deep morning twilight at approx RA 17:08, DEC -29. My tentative observation (awaiting confirmation tomorrow morning):- made the comet Mv -0.5 0.5 coma, DC6 in a 18cm Newtonian, and Mv -0.8 DC8 in a 10 x 90 Binocular.

My overall impression of this comet, is that it has heaps of "attitude"... it refuses to lay down and die, and just keeps getting in my face (not that I'm complaining). It has defied all expectation to totally fry away, its sported an ion tail etc. John Bortle is right:- we are indeed "witness to history".

Thank you Terry for discovering it, and for contributing so many wonderful observations, photos and measurements just on your own. Thanks also to the world-wide astro-community who have gone "hard as" to secure valuable data on Terry's comet. Terry:- you're a legend... my personal admiration for you continues to rocket totally "off scale"!!

Best wishes

Graham W. Wolf
Barber Grove Observatory (BGO), Lower Hutt, NZ

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BMayfield

December 18, 2011 at 8:02 pm

TofL, John SHeff was quicker on the keyboard than I with the planetary velocity points. Also, angular momentum is a vector quantity defined as Mass x distance^2 / time. Since Jupiter's mass is greater than all the other planets combined it carries most of this systems angular momentum. The Great Celestial Mechanic wants us to learn about him and about his wonderful creative works (such as the amazing comet Lovejoy) according to "an accurate knowledge of truth". (1 Tim 2:3,4)

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Graham Wolf

December 19, 2011 at 6:03 pm

Have confirmed yesterday's observation of Lovejoy C/2011 W3, with another this morning. Some other observers claim a faint tail in PA 240, but I have yet to see THAT myself. This morning, a waning crescent Moon hung over Libra. Much lower down and to the right, I could make out M6 and M7 in Scorpius in my 10 x 50 Binocs, as I "advanced" downwards towards Antares, via Epsilon Scorpii. I observed from 4:50 to 5:10am NZDT. Trying to estimate the comet's brightness (Sirius is Mv -1.47, Canpous - 0.72, and Alpha Cen -0.28) by using bright stars and correcting for extinction is a tough ask with twilight rapidly advancing.

The comet has moved a few degrees closer to Mv 2.28 star Epsilon Scorpii. I have personally found the book:- "Atlas of the Night Sky" by Storm Dunlop, most helpful. Tirion's constellation Chart for Scorpius rates a special mention.

For those interested:- here's my latest observations

Dec 18.674 UT Mv-0.5 0.5 arcmin DC6 18cm f5 Newt 100x
Dec 18.677 UT Mv-0.8 ~ 1 arcmin DC8 10x90 Binoc
Dec 19.674 UT Mv-0.0 ~ 1 arcmin DC6 10x50 Binoc

Terry:- your wonderful comet is still up there in my local Lower Hutt Eastern dawn skies. It didn't die on us after all... I just knew you'd take good care of it!

Regards and clear skies from New Zealand

Graham W. Wolf (WOL01)

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Graham Wolf

December 20, 2011 at 6:06 pm

Greetings from NZ.

Comet Lovejoy (C/2011W3) underwent an outburst overnight (NZDT) easily noticed at dawn in NZ a few hrs ago. It has now showing a faint tail that extends several degrees in the 11 o'clock position upwards past Mv 2.88 star Epsilon Scorpii!

Observations were made from the Barber Grove Observatory (BGO) at Lower Hutt, NZ, facing low in the East, just a little left of, and below a waning crescent Moon... both with a 10 x 50 Binocular, and plotting between faint Scorpius stars near Antares. Comet appeared semi-stellar and as bright as Canopus (Mv -0.72), corrected for extinction. Skies were semi-overcast at the time, with clear patches to the East.

Dec 20.698 UT Mv -0.8 coma ~1' DC8 Tail 8.6 deg to Mv +2 limit
Dec 20.708 UT Mv -0.6 coma ~1' DC6 Tail 5.8 deg to Mv +1 limit

At 200x in an 18cm f5 Newtonian at Dec 20.702 UT (16h 50m UT), the coma appeared elongated at 1.4 x 1.0 arcminute... down to an Mv +3 limit. No tail spines or synchrones were observable to an Mv +3 limit.

Although no post-perihelion astrometric data are yet to hand, it personally appears (plotting against the background stars) that the actual comet position this morning (NZDT) is within 1/2 deg error at worst. Several leading Australian amateurs in NSW have made short DSLR images this morning:- that clearly show the tail in similar detail to my own visual observations.

All I can say is thus:- "comets are capricious and quite unpredictable". Terry's 3rd comet continues to surprise and wonderfully amaze. OBSERVE, RECORD, REPORT (and enjoy)!

Regards

Graham Wolf:- (BGO) Lower Hutt, New Zealand

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Jon Hanford

December 21, 2011 at 9:56 pm

A beautiful time lapse video of Comet Lovejoy rising over Western Australia on the morning of Dec. 21st has been posted on vimeo: http://vimeo.com/34007626

One can even make out separate gas and ion tails in the video! Sorta reminds me visually of Comet West's morning apparition in 1976, though not as bright. I wonder if the nucleus will eventually fragment like comets West and Ikeya-Seki?

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Bill Simpson

December 22, 2011 at 9:20 am

GO to http://www.adelaide.com.au and click on the front page comet story then click on the still photo image at the top of the box with the first comet picture for an awesome image of it.

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BMayfield

December 23, 2011 at 1:05 pm

Jon, your question about Lovejoy's possible fragmentation came as a suprize to me, given my naive impression that after surviving the sresses of perihelion it would be good to go, since the forces acting on it are now lessening rapidly. A little reading up on Kreutz-group comets however confirms that they can and do break up all along their orbits. This only makes sense, since the magnificent tail formations observed by ya'll down under provide ample proof of tremendous continuing erosion by radiation and solar wind. (Graham Wolf, your wonderfully detailed description your veiw from NZ gave even this Texan a bad case of hemispherial location envy!) Assuming this solar survivor continues to servive, has anyone computed it's projected orbit now? How far is it destined to go (apihelion) and when will it return (period). Thanks again from all of us on the wrong side of the planet.

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BMayfield

December 23, 2011 at 2:20 pm

I was at first surprized by Jon Hanford's question about possible fragmentation. Naively, I thought 'it's survived perihelion and the sresses are now lessening by the moment, so why shouldn't it now be good to go for at lest another orbit?' Reading up on Kreutz-group comets in Wikipedia informed me that they can and do indeed break up all along their orbits. Thinking about it, this only makes sense, since the wonderful tail formatations ya'll mates from down under are seeing and reporting are ample evidence of tremedous solar wind and raditational erozion. (You're giving even this Texan a bad case of hemispherical locaton evny, but please keep the reports coming.) Assuming it continues to survive however, has anyone computed it's orbit now? How far will it go (apihelion) and when will it return (period)? Thanks from the wrong side of the earth.

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