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Fraser
2005-Jul-15, 03:56 PM
SUMMARY: After getting smashed by Deep Impact two weeks ago, Comet Tempel 1 has finally settled back down and appears normal again. Right after the impact, material streamed off the comet, traveling 700 to 1000 km/h (430 mph to 600 mph). This created a large, diffuse halo around the comet which faded away over the next few days. The same jets astronomers could see before the impact are still streaming away, so it appears Tempel 1 suffered very little damage.

View full article (http://www.universetoday.com/am/publish/comet_tempel1_back_sleep.html)

What do you think about this story? Post your comments below.

VanderL
2005-Jul-15, 04:10 PM
From the article:


Further images obtained with, among others, the adaptive optics NACO instrument on the Very Large Telescope, showed the same jets that were visible prior to impact, demonstrating that the comet activity survived widely unaffected by the spacecraft crash.


When they omit the finding of increased activity of the two pre-impact jets, and the emergence of several new jets at 15 hours post-impact (as imaged by the NOT telescope in La Palma, Spainsee here (http://deepimpact.umd.edu/collab_pub/spacep.shtml)), does this mean they are not telling the whole truth, or can we call it cherrypicking to support their views, or worse?

Cheers.

antoniseb
2005-Jul-15, 04:28 PM
Originally posted by VanderL@Jul 15 2005, 04:10 PM
When they omit the finding of increased activity of the two pre-impact jets, and the emergence of several new jets at 15 hours post-impact (as imaged by the NOT telescope in La Palma, Spainsee here (http://deepimpact.umd.edu/collab_pub/spacep.shtml)), does this mean they are not telling the whole truth, or can we call it cherrypicking to support their views, or worse?
Hi VanderL,

As I have said in some other threads to this same criticism, I agree that this is an interesting point. You have done a nice job of trying to collect all this data, and you have it organized pretty well. Why not send an email to someone who can actually answer the question either at NOT/WHT or from the Deep Impact science team (seriously). I suggest crafting the wording so it doesn't sound like an accusation of conspiracy to hide the real story. Then when you get responses from these people, post them here (or some other appropriate thread).

Questions I'd like to see answered are:
- Given that we now know the 41 hour rotation period and orientation of Tempel 1, what is the map of known jets observed prior to collision
- Where did the new jets eminate from?
- How long did they keep jetting?
- What were these jets made of?
- Why are popular news stories saying there are no new jets?

Can anyone think of any other questions that are possibly answerable, and simply about VanderL's question here?

VanderL
2005-Jul-15, 06:49 PM
Originally posted by antoniseb+Jul 15 2005, 04:28 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (antoniseb @ Jul 15 2005, 04:28 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-VanderL@Jul 15 2005, 04:10 PM
When they omit the finding of increased activity of the two pre-impact jets, and the emergence of several new jets at 15 hours post-impact (as imaged by the NOT telescope in La Palma, Spainsee here (http://deepimpact.umd.edu/collab_pub/spacep.shtml)), does this mean they are not telling the whole truth, or can we call it cherrypicking to support their views, or worse?
Hi VanderL,

As I have said in some other threads to this same criticism, I agree that this is an interesting point. You have done a nice job of trying to collect all this data, and you have it organized pretty well. Why not send an email to someone who can actually answer the question either at NOT/WHT or from the Deep Impact science team (seriously). I suggest crafting the wording so it doesn&#39;t sound like an accusation of conspiracy to hide the real story. Then when you get responses from these people, post them here (or some other appropriate thread).

Questions I&#39;d like to see answered are:
- Given that we now know the 41 hour rotation period and orientation of Tempel 1, what is the map of known jets observed prior to collision
- Where did the new jets eminate from?
- How long did they keep jetting?
- What were these jets made of?
- Why are popular news stories saying there are no new jets?

Can anyone think of any other questions that are possibly answerable, and simply about VanderL&#39;s question here? [/b][/quote]
Hi Antoniseb,

There are so many questions that need answering, the question about the jets is one of them. Maybe it&#39;s a good idea to ask the experts, I&#39;ll try it. I&#39;ll let you (and every body here, no worries) know what the answers are.

Cheers.

antoniseb
2005-Jul-15, 08:38 PM
Originally posted by VanderL@Jul 15 2005, 06:49 PM
There are so many questions that need answering, the question about the jets is one of them.
I think you&#39;ll have a greater chance of getting what you need if you just start with the questions about the new jets. If you find someone who is responsive, ask another question after they finish answering the jets question (my suggestion, not some secret protocol).

The Messenger
2005-Jul-18, 04:46 AM
The most pertinant data is the spectrum observed during the flash, before the dust cloud obscured everything, and the ionization spectrum that emerged a few days later.

It will be up to NASA to furnish us with the initial spectral results, but don&#39;t hold your breath. In the post-impact news conference, related questions were dodged several times, and we were also told it would take up to two weeks to figure out the IR temperature <_<

In the very first press conference, it was stated that they could not even interpret the spectrum. Velocity or crowded?

Don&#39;t Shoot

antoniseb
2005-Jul-18, 12:52 PM
Originally posted by The Messenger@Jul 18 2005, 04:46 AM
it was stated that they could not even interpret the spectrum. Velocity or crowded?
I&#39;d guess crowded, and poor spectral resolution. Possibly also they needed to do some work to subtract the pre-impact spectral signiture. Velocity shouldn&#39;t be a big deal since the materials were travelling at about a millionth the speed of light.

VanderL
2005-Jul-21, 11:36 AM
Hi all,

I received an e-mail response from ESO about the jets; to paraphrase:

"they can&#39;t answer the question why the NOT people did see jets, because they don&#39;t have the data. Their data show no additional jets, but the procedure is difficult and they hope to give more details in a few months."

I also asked the NOT team about the jets, but they haven&#39;t answered yet.

Meanwhile there&#39;s still the discrepancy; there was another telescope that had positive identification of new jets (don&#39;t know which one, but I&#39;ll look it up), could it be due to the spectral range of the detectors? Has anybody seen any new data release clarifying this issue?

Cheers.

antoniseb
2005-Jul-21, 04:10 PM
Thanks for pursuing this VanderL. I have not seen any new data on this. All the information I&#39;ve seen is secondary sources (jouranlism, not research). I&#39;m guessing that no one on this forum is further along on this topic than you. Please keep it up, and thanks again.

Guest
2005-Jul-23, 10:02 AM
Here (http://pr.caltech.edu/media/Press_Releases/PR12721.html) is a new press release from the Palomar Observatory showing (actually when I see the images, linked to at the bottom of their page, I don&#39;t see it clearly) additional evidence of jets. So even if some people say the opposite (maybe their data aren&#39;t detailed enough), there really are jets that formed after impact. The press release says "dust and gasses", but that is probably their preconceptions talking, because the evidence says "dust as fine as talcum powder". This press release talks about a region that shortly after impact was small and extended to a larger region within a day.

Clearly, if these results are matched with the water and volatiles data (or better, their absence), the "snowball" idea vanishes before the proverbial Sun.

Any thoughts on the nature of these jets?

Cheers.

VanderL
2005-Jul-23, 10:10 AM
Originally posted by Guest@Jul 23 2005, 10:02 AM
Here (http://pr.caltech.edu/media/Press_Releases/PR12721.html) is a new press release from the Palomar Observatory showing (actually when I see the images, linked to at the bottom of their page, I don&#39;t see it clearly) additional evidence of jets. So even if some people say the opposite (maybe their data aren&#39;t detailed enough), there really are jets that formed after impact. The press release says "dust and gasses", but that is probably their preconceptions talking, because the evidence says "dust as fine as talcum powder". This press release talks about a region that shortly after impact was small and extended to a larger region within a day.

Clearly, if these results are matched with the water and volatiles data (or better, their absence), the "snowball" idea vanishes before the proverbial Sun.

Any thoughts on the nature of these jets?

Cheers.
That was me of course, I wanted to add that the increase in brightness was five-fold. The data were collected in the mid-infrared part of the spectrum, this might explain differences with other observatories:


Early results from the data, in images taken just minutes after impact, showed a possible plume of dust and gas extending outward some 320 km (200 miles) from the comet&#39;s center, roughly coinciding with the site of the probe&#39;s final demise.

This apparent dust plume has persisted for several nights, allowing astronomers to watch the comet&#39;s slow rotation. The night after impact the plume was on the far side of the comet, but was visible again the next evening as the comet&#39;s rotation brought it back into view. Two days after impact, the plume was seen again, this time extending about 200 km (124 miles) from the comet&#39;s center. According to Bidushi Bhattacharya of the California Institute of Technology&#39;s (Caltech) Spitzer Science Center, "This could be indicative of an outburst of gas and dust still taking place near the region of the impact."

Cheers.

Ola D.
2005-Jul-24, 11:00 PM
Originally posted by VanderL@Jul 21 2005, 11:36 AM
Hi all,

I received an e-mail response from ESO about the jets; to paraphrase:

"they can&#39;t answer the question why the NOT people did see jets, because they don&#39;t have the data. Their data show no additional jets, but the procedure is difficult and they hope to give more details in a few months."
Hi VanderL,

Can you please let me know the name of the contact at the ESO team?

I did contact Dr. Hermann Boehnhardt at the ESO team last week about the jets questions Anton proposed, and he replied back saying that he may not be the right person to answer such questions.

To quote his reply,

I may not be the right person to answer your question about the jets. This
answer should come from the DI mission people since they claim to know the
rotation axis orientation and may have also a more detailed few of the
location of active regions on the nucleus. My personal attempts referred to
ground-based observations and a first - maybe naive - interpretation of the
data. Since these results are in review in a scientific journal right now, I
don&#39;t want to get out with it to a wider community.

Moreover, I really believe that the DI mission will provide ground truth and
should be taken as the key reference here.

I hope for your understanding

best regards,

hermann Boehnhardt

Actually, I did contact one of the DI mission scientists about this question, and had no reply; that&#39;s why inturn I directed the question to Dr. Hermann.

VanderL
2005-Jul-25, 04:45 PM
Hi Ola D.,

The person responding to my question was Henry Boffin, I can forward the message if you want, just PM me you e-mail address.

Cheers.

P.S. The people from the NOT telescope in La Palma, Spain haven&#39;t responded (yet).