Announcing your Results Webchat April 23, 1996 with STScI's Christian Ready

TOPIC: What we've learned!

Christian (STScI): ... . . . Tue, Apr 23, 11:29AM PDT (-0800 GMT)
Greetings, I hope everyone enjoyed the Live From HST broadcast. Some friends of mine and I are here to answer any questions that you may not have had a chance to ask. So please feel free to fire away.

Gayle (London, On): ... . . . Tue, Apr 23, 11:32AM PDT (-0800 GMT)
Hi Christian, thanks for coming, I didn't get to see the show so I figured I'd come here to get the low down.

Christian (STScI): .. . . . . Tue, Apr 23, 11:32AM PDT (-0800 GMT)
Gayle, was that directed to me?

Christian (STScI): ... . . . Tue, Apr 23, 11:34AM PDT (-0800 GMT)
Gayle, I see that second one of yours was directed to me. The broadcast went very well. I think people learned a lot. Do you, or anyone else, have any questions about HST?

Marc (California): ... . . . . Tue, Apr 23, 11:35AM PDT (-0800 GMT)
Hi Christian, What do you do at STScI. Also, did you participate in the broadcast today at all?

Marc (California): .... . . . Tue, Apr 23, 11:38AM PDT (-0800 GMT)
Gayle, I can see that we got about 75 questions during the broadcast. Significantly less then last time. I think the material is a bit harder to follow then last time. Not because of anything we could control, but because it is really, truly hard to find meaning in Marc and Heidi's images. Even though I am an insider, I still struggle with it a bit.

Christian (STScI): .... . . . Tue, Apr 23, 11:39AM PDT (-0800 GMT)
Hi Marc, I'm an astronomer here at STScI, although I didn't actually appear on camera, I was speaking to some of the students before hand about HST and what I do. Here at STScI, I work as a Program Coordinator. I help to develop observation proposals to use the HST, and then I implement those proposals and turn them into the actual observations. These observations are what you see on the web and such.

Marc (California): .... . . . . Tue, Apr 23, 11:40AM PDT (-0800 GMT)
Christian, Are there more observations planned for Pluto or Neptune by Marc or Heidi? What about for other PIs interested in Neptune or Pluto?

Gayle (London, On): .... . . . . Tue, Apr 23, 11:41AM PDT (-0800 GMT)
I can imagine, I would think it's rather like looking at X-rays, unless you know what you're looking for it's hard to interpret.

Marc (California): . . . . Tue, Apr 23, 11:42AM PDT (-0800 GMT)
Tornadoes, Did you in fact take temperature and cloud cover measurements and send them in? I thought it was neat the way the cloud cover shown on TV seemed to match fairly well what the satellite image produced.

Christian (STScI): . . . . Tue, Apr 23, 11:43AM PDT (-0800 GMT)
I'm not sure what Marc and Heidi are proposing to do with HST in the future. I'm not a planetary type myself, so I really don't work on the planet observations. I think that with the new findings with Hubble, and particularly the newfound popularity thanks to the LHST, there are going to be a lot of new observations proposed by many PI's.

Tornado Kids: . . . . Tue, Apr 23, 11:43AM PDT (-0800 GMT)
Today's program went very well. I really like it went they demonstrate some of the experiments from the teacher's resource pack. I like the enthusiasm of the researchers.

Marc (California): . . . . Tue, Apr 23, 11:44AM PDT (-0800 GMT)
Gayle, I thought that last time you went to a satellite store to watch the broadcast. I gather that wasn't a good option this time?

Marc (California): . . . . Tue, Apr 23, 11:45AM PDT (-0800 GMT)
Christian, What is your specialty and what are the hot new things we can be expecting from Hubble in that area? The HST is somewhat remarkable in that it seems to continually produce results that make the mainstream media?

Gayle (London, On): . . . . . Tue, Apr 23, 11:46AM PDT (-0800 GMT)
Christian: Are there any parts of the HST that get in the way of the image coming in? (like the secondary mirror/baffle etc.)

Tornado Kids: . . . . . Tue, Apr 23, 11:46AM PDT (-0800 GMT)
Yes, Marc we did. I was neat how everything matched up with the satellite photo. My children were quite excited about how alike the data matched.

Marc (California): . . . . . Tue, Apr 23, 11:46AM PDT (-0800 GMT)
Tornadoes, How many of the activities from the TeacherŐs Guide did you do? Is the person typing a student or teacher?

Marc (California): .. . . . Tue, Apr 23, 11:48AM PDT (-0800 GMT)
Tornado, I was personally surprised that the data did match up for that example. When we planned the activity, we thought we would really be demonstrating how a group of students could not produce accurate maps because there wouldn't be enough data points.

Christian (STScI): . . . . Tue, Apr 23, 11:49AM PDT (-0800 GMT)
Marc, my specialty is implementing observations taken with the Wide Field/Planetary Camera 2 (WFPC2). Many of the observations that I have participated in involve probing the remains of stellar death. It's exciting to see that stellar death (planetary nebulae, for example) is really much more intricate than what was previously thought. Another area that I have worked on is understanding the dynamics of distant galaxies. Stellar death is my research area, however, so I like those kinds of observations the most.

Gayle (London, On): .. . . . Tue, Apr 23, 11:52AM PDT (-0800 GMT)
I'd love to hear more about Stellar Death. How do you research this type of occurrence?

Christian (STScI): .. . . . Tue, Apr 23, 11:52AM PDT (-0800 GMT)
Gayle, No, not really. The secondary mirror only blocks a small part of the field. However, since the targets are so far away, the resulting 'blockage' is nonexistent. Instruments actually only see a very small part of the HST 'field of view' When we want to bring a target on an instrument, we have to move the telescope slightly to allow the target to occupy a particular place in the FOV.

Tornado Kids: .. . . . Tue, Apr 23, 11:52AM PDT (-0800 GMT)
We did about all of them. The person typing is a combination of student and Mom. We couldn't do Bouncing Data around the World, not enough people. I hope to get some other homeschooling families together to do that experiment later.

Marc (California): .. . . . Tue, Apr 23, 11:53AM PDT (-0800 GMT)
Christian, Are there categories of the ways stars die? If so, what are the basic different processes that might happen? Have these theories changed recently due to the HST discoveries?

Gayle (London, On): ... . . . Tue, Apr 23, 11:54AM PDT (-0800 GMT)
Tornado, I'm in if you'll have me? and I know of some other homeschoolers who'd be very interested.

Marc (California): ... . . . Tue, Apr 23, 11:55AM PDT (-0800 GMT)
Hi Tornado, A teacher who is a learner...the best kind. I am really intrigued by what causes a parent to decide to homeschool. I think it would be so hard. If I had kids, I think I would send them to public school but also do extra activities with them after hours. What process led your decision or Gayle's to homeschool?

Christian (STScI): ... . . . Tue, Apr 23, 11:56AM PDT (-0800 GMT)
Stellar remnants are actually abundant in the sky. In fact, some are much larger than the full moon! The problem is that their overall surface brightness is very faint, and that's why we need telescopes to see them. Research, then, amount to trying to understand how a star lives, and how the processes that allow it to live evolve over time. You can then make a model of it and generally you expect a star to loose so much material that it creates a shell around the core. Observations with ground telescopes generally reveal a shell surrounding an exposed core. Hubble, on the other hand, is showing us that these structures are not so simple, and that there is a lot more going on there. (long, sorry)

Christian (STScI): . . . . Tue, Apr 23, 12:01AM PDT (-0800 GMT)
Marc, Yes there are many categories. The way a star dies depends on the same factors that create it in the first place. The most important is Mass. The more massive a star is, the hotter it burns and the shorter it lives. This results in a supernova explosion. Less massive stars (like our sun), run out of stellar fuel more gradually (and they live longer to begin with). So they evolve into red giant stars (i.e. they swell up) and loose material. Eventually, this results in a non-explosive loss of a lot of stuff. It was thought that these so called "Planetary Nebulae" were simple spheres of gas surrounding the exposed cores. HST, on the other hand, reveals unprecedented structure, suggesting that stellar death is not as simple as previously thought.

Marc (California): .. . . . Tue, Apr 23, 12:01AM PDT (-0800 GMT)
Christian, Are you saying that a dying star can be identified because more of its material is in the shell then in the core. That it is a rather gradual process and not a sudden change?

Tornado Kids: .. . . . Tue, Apr 23, 12:01AM PDT (-0800 GMT)
What is an example of a Stellar remnant? Is the Eagle Nebula a Stellar remnant?

Marc (California): . . . . . Tue, Apr 23, 12:03AM PDT (-0800 GMT)
So then our sun will become a red giant. So can we already detect any swelling in our sun over the short time we've studied it or are the changes way too gradual for that?

Christian (STScI): . . . . Tue, Apr 23, 12:03AM PDT (-0800 GMT)
That's right. In the case of a Sun-like star, enough material is lost over time that it creates a shell. For very massive stars (say, 20 times the mass of the sun), there is a supernova explosion. If one goes off, you will notice the change because a "new" star appears in the sky.

Christian (STScI): . . . . Tue, Apr 23, 12:04AM PDT (-0800 GMT)
Marc, our Sun will become a red giant, but not for another 5 billion years. Even then, the change will take millions of years.

Marc (California): .... . . . Tue, Apr 23, 12:06AM PDT (-0800 GMT)
How do you know it will take 5 billion years. What is it about our sun that reveals it's present age? (which I assume you need to tell how long it has to go)

Christian (STScI): .... . . . Tue, Apr 23, 12:06AM PDT (-0800 GMT)
Tornado Kids. Hi! Actually, the Eagle Nebula is a gas region where stars are forming. Sort of like a stellar nursery. An example of the stellar remnant would be the Cat's Eye nebula (one of "my" observations) and the Hourglass nebula. You can view them at the STScI web site.

Marc (California): .... . . . Tue, Apr 23, 12:10AM PDT (-0800 GMT)
Gayle. Thanks for the articulate answer. I think at one point you said that you ran a once per week session for local kids on technology. Is that right? Do other parents run other sessions in what they know lots about?

Gayle (London, On): ... . . . . Tue, Apr 23, 12:10AM PDT (-0800 GMT)
Christian: this Stellar Death sounds very interesting is there current k-12 info about it? Especially, what data has been released which has results and info found by HST?

Christian (STScI): . . . Tue, Apr 23, 12:10AM PDT (-0800 GMT)
Well, we certainly can't use a stopwatch :) so we have to estimate it based upon current models of stellar evoloution. As I said before, the determining factor in the life (and death) of a star is the star's mass. We know the mass of our sun very precisely, and we find that as stars go, it's a relatively ordinary, "dwarf" star. From these models, we expect a 10 billion year "main sequence" or normal stage of nuclear burning. Based on geologic models of the earth, we know that the earth has been around for 4.5 billion years. Let's give the earth 500 million years to form after the sun did. That makes the sun about 5 billion years old.

Tornado Kids: .. . . . Tue, Apr 23, 12:12AM PDT (-0800 GMT)
Yes we have seen the Cat's Eye nebula, it is very impressive. It fire's the imagination on how vast space is. The colors of red and green make a vivid contrast. It is one of my childrenŐs favorites.

Christian (STScI): .. . . . Tue, Apr 23, 12:13AM PDT (-0800 GMT)
Gayle: Well, I don't know exactly what k-12 info has been released about stellar death. I can say for sure that some of these observations and their results from HST has been made public. Your best bet would be to search the STScI web site, and you'll see a whole bunch of press releases, many of them of stellar remnants.

Christian (STScI): . . . . . Tue, Apr 23, 12:14AM PDT (-0800 GMT)
Tornado: Oh, I'm so glad you like it! It's one of my favorites, and I'm not just saying that. What's so neat about the image is that it's showing us not one, but two stars that have undergone this phenomenon. Their shells are intertwined, giving it it's namesake.

Christian (STScI): . . . . . Tue, Apr 23, 12:17AM PDT (-0800 GMT)
My pleasure. Good questions, and I hope to do it again!

Tornado Kids: . . . . . Tue, Apr 23, 12:17AM PDT (-0800 GMT)
Did you enhance the colors in the photo, just as they did with the Hubble's pictures of Pluto and Neptune?

Marc (California): . . . . . Tue, Apr 23, 12:18AM PDT (-0800 GMT)
I think I'll go too. Good bye Christian and Tornado Kids. Thanks to both of you for coming!

Christian (STScI): .. . . . Tue, Apr 23, 12:19AM PDT (-0800 GMT)
Tornado: Not really. They were taken in separate colors, and combined to give a "true color" representation of the real deal.

Tornado Kids: .. . . . Tue, Apr 23, 12:19AM PDT (-0800 GMT)
Thank you Marc and Christian.

Christian (STScI): . . . . . Tue, Apr 23, 12:20AM PDT (-0800 GMT)
Marc, thanks for having us.

Christian (STScI): . . . . . Tue, Apr 23, 12:22AM PDT (-0800 GMT)
Cheers, I'm signing off myself.