January 2009 - Utah-Astronomy - mailman.xmission.com

Re: [Utah-astronomy] White dwarfs and YOU
by zaurak＠digis.net 25 Jan '09

25 Jan '09

Chuck, You wrote: " I'm not sure that planetary nebula are illuminated by the central star" That was what the professor form Ohio States' Astronomy Department stated. Again I am no Phd, but Perhaps the idea that the Universe is 13.5 billion years old needs rethinking or perhaps that it takes 13 billion years for white dwarfs to exhaust themselves, I read mention that in some cases it takes 2 billion. She writes: "The ejected outer layers, heated by the hot new white dwarf, form an emission nebula. An emission nebula of this sort - ejected gas which is being excited by a hot white dwarf - is called a planetary nebula. " Erik --- chuck.hards(a)gmail.com wrote: From: Chuck Hards <chuck.hards(a)gmail.com> To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> Subject: Re: [Utah-astronomy] White dwarfs and YOU Date: Sun, 25 Jan 2009 20:18:05 -0700 No, I didn't mention that. Jerry was the one who posted about the visibility of white dwarfs in a cataclysmic variable system, not Bishop. I was attempting to distance that from Bishop and try to underline the differences. In my post, Bishop's comments were in quotes, mine were not. Sorry for the apparent confusion. On Sun, Jan 25, 2009 at 8:05 PM, <zaurak(a)digis.net> wrote: > You also mention that he is talking about white dwarfs from cataclysmic > double stars. Perhaps in the case of planetary nebula (I believe most of > these are not from cataclysmic doubles), that there is nothing to see until > the "life" of White Dwarf is turned on, to illuminate the gases expelled > from the red giant. Simply the intermediate period is before the nebula is > visible. Again, I imagine most white dwarfs are not the product of double > star systems gone wrong. > > _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

2 1

Re: [Utah-astronomy] White dwarfs and YOU
by zaurak＠digis.net 25 Jan '09

25 Jan '09

Our perhaps Ken Meyer's favorite "Pink World", ha ha (inside joke) --- chuck.hards(a)gmail.com wrote: From: Chuck Hards <chuck.hards(a)gmail.com> To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> Subject: Re: [Utah-astronomy] White dwarfs and YOU Date: Sun, 25 Jan 2009 20:20:22 -0700 I recommend playing Pink Floyd's "Dark Side of the Moon" when watching Jim's expansion images... *;o) * On Sun, Jan 25, 2009 at 7:48 PM, Jim Gibson <jimgibson00(a)yahoo.com> wrote: > By the way, for your viewing pleasure I have uploaded a gif file of M1 > showing the expansion of M1 over 30 years. There are 2 images, one taken in > 1970 and the other in 2000. While M1 is not a White Dwarf the expansion of > the nebula may lend itself to some of the discussion we have been having. > > > See image here: http://www.slas.us/gallery2/main.php?g2_itemId=868 > > _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

1 0

Re: [Utah-astronomy] White dwarfs and YOU
by zaurak＠digis.net 25 Jan '09

25 Jan '09

What I find most striking about M1, was that its supernova was observed and recorded by man. --- jimgibson00(a)yahoo.com wrote: From: Jim Gibson <jimgibson00(a)yahoo.com> To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> Subject: Re: [Utah-astronomy] White dwarfs and YOU Date: Sun, 25 Jan 2009 18:48:29 -0800 (PST) By the way, for your viewing pleasure I have uploaded a gif file of M1 showing the expansion of M1 over 30 years. There are 2 images, one taken in 1970 and the other in 2000. While M1 is not a White Dwarf the expansion of the nebula may lend itself to some of the discussion we have been having. If the luminosity were constant and I am not saying it is then one can imagine just by the expansion alone that luminosity would have to be spread out over a larger area. Heck, I have seen 30 years twice. That expansion is just a poof. See image here: http://www.slas.us/gallery2/main.php?g2_itemId=868 JG _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

3 2

Re: [Utah-astronomy] White dwarfs and YOU
by zaurak＠digis.net 25 Jan '09

25 Jan '09

Yes Dan, I know what you are saying, you can't expect a novice to see the same detail as an experienced observer. It seems white dwarfs have a long and varied existence (avoiding saying "life") they start out hot and end up very cool. I guess PHd candidates need something to write their thesis on, redefining white dwarfs is surely fair game. Erik --- outwest112(a)yahoo.com wrote: From: daniel turner <outwest112(a)yahoo.com> To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> Subject: Re: [Utah-astronomy] White dwarfs and YOU Date: Sun, 25 Jan 2009 16:11:49 -0800 (PST) Erik: I guess the status of central stars is like the status of Pluto. It depends on where you draw the lines and both points are currently under debate. This is good and even healthy. We don't yet have a good definition of "precursor white dwarves" the separates them from Wolf Rayet stars and OVI classic white dwarves. It's a minor quibble and more a study of human nature than astronomy. My take on what advanced amateurs like Dave Bernson can see that the rest of us cannot is that it's a training issue. The first time I saw the cc in M57 was an extaordinary night at Wolf Creek with an 18" dob. After that I found it easier to see it each time I spend the time to look. Dave sees things because he knows where and how to look. Jay Eades described using averted vision when he looked at M74 and he was not completely satisfied with the view. To guys like Dave and Stephen James O'meara averted vision is second nature. The more I look the more I see and the better I get at using averted vision. I'm not through learning stuff in the hobby yet. DT --- On Sun, 1/25/09, zaurak(a)digis.net <zaurak(a)digis.net> wrote: > From: zaurak(a)digis.net <zaurak(a)digis.net> > Subject: Re: [Utah-astronomy] White dwarfs and YOU > To: "Utah Astronomy" <utah-astronomy(a)mailman.xmission.com> > Date: Sunday, January 25, 2009, 3:37 PM > Hi Chuck, > > I am far from expert, but that seem contrary to what > Professor Ryden (Ohio State) says. She indicates the White > Dwarf outlives the planetary nebula. > > As far as what can be seen visually, Zwicky seemed to push > the envelope when he claimed he could visually detect motion > in galaxy clusters. Most contemporaries thought him crazy, > although time proved they do have motion. I am not sure this > proves he could see the motion though. > I think it easy to convince yourself you are seeing a > central star after you have seen it once. I agree with > Daniel that I have seen many stars in the center of many > planetary nebula, with the Grim and they seem likely to be > White Dwarfs. Bernson can describe many objects from > memory, in detail, without looking through an eyepiece, I > find myself not always seeing the detail he describes. I > have noticed many at public star parties scratching their > heads over details they are told they "should" be > seeing. I tell people that the more you observe the more you > will see, past experiences and views do matter. > > The 20" dob I observed with also yielded many central > stars in planetary nebula. I have only observed the Messier > Planetary Neb with smaller scopes, under very dark skies I > recall seeing the central star of M57 with a 10-12" > scope. > > Erik > > Quoting Ryden: > > "An asymptotic giant branch star (a red giant star > which is about to run out of fuel) is not very stable. It > undergoes thermal pulses during which the outer layers of > the star are ejected into space. Finally, when the star > totally exhasts it fuel supply, its core collapses and heats > up. The core becomes a very hot white dwarf, with a surface > temperature of 100,000 Kelvin, or more. > The ejected outer layers, heated by the hot new white > dwarf, form an emission nebula. An emission nebula of this > sort - ejected gas which is being excited by a hot white > dwarf - is called a planetary nebula. (This confusing name > goes back to the 18th century; viewed through a small > telescope, the fuzzy disk of a planetary nebula looks a bit > like the fuzzy disk of a planet like Uranus. > After the planetary nebula fades, the white dwarf will > still be visible. White dwarfs shine because they are hot; > although a white dwarf has no internal power source, it > takes billions of years for a white dwarf to cool down. > Thermal energy in the interior of a white dwarf is carried > to the surface by conduction, then radiated away." > > > > --- chuck.hards(a)gmail.com wrote: > > From: Chuck Hards <chuck.hards(a)gmail.com> > To: Utah Astronomy > <utah-astronomy(a)mailman.xmission.com> > Subject: Re: [Utah-astronomy] White dwarfs and YOU > Date: Sun, 25 Jan 2009 16:06:40 -0700 > > The same can be said of your "central star" > statement. From what I've been > reading, now stellar evolutionists believe that the white > dwarf stage isn't > clearly reached until the planetary nebula has ceased to > exist- an > incredibly short lifespan of only a few tens to a hundred > thousand years is > typical for a planetary nebula. Central stars of visible > planetaries are > considered pre-white dwarf stars. The knowledge base > continues to be > refined as time passes. It may be that Bishop knows this > but wanted to > point out examples of stars unambiguously settled in the > white-dwarf stage. > Firmly in the stellar grave yard, with no evidence of > recent nuclear > reactions in the immediate environ. > > Bishop never made an absolute statement such as you imply; > he mentioned no > apertures at all. A 10" telescope isn't > considered a small telescope by > the general public- or with many serious amateurs. > It's pretty big to me, > and I've been doing this since 1968. Hair-splitting, > semantic games can > always be played with someone's words trying to > communicate astronomy to a > wide audience. Only a tiny fraction of people would jump > on a soapbox and > find issue with Bishop's exact choice of words. I > wholeheartedly approve > of Bishop's piece, and your statement does nothing to > provide contrary > evidence. > > On Sun, Jan 25, 2009 at 3:36 PM, daniel turner > <outwest112(a)yahoo.com> wrote: > > > The problem comes when someone writes with a voice of > authority about what > > "can't be done". This causes people to > immediately try to prove them wrong. > > Bishop may regret his choice of words but it's > best to remember that just > > because you haven't seen something, doesn't > mean the other people haven't > > either or that next year they might be able to. > > > > I look at dozens of planetary nebula every year, and a > large fraction of > > these have an easily seen central star. Most can be > seen with a 10" which > > is no longer considered a particularly large telescope > anymore. The > > standards for an "amateur" or > "backyard" or "average" telescope may > continue > > to change change with time. > > > > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > Visit the Photo Gallery: http://gallery.utahastronomy.com > Visit the Wiki: http://www.utahastronomy.com > > > > > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > Visit the Photo Gallery: http://gallery.utahastronomy.com > Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

4 4

Re: [Utah-astronomy] White dwarfs and YOU
by zaurak＠digis.net 25 Jan '09

25 Jan '09

Kim, I am quoting from the article I posted earlier. "Under the extreme conditions which prevail within a white dwarf, the laws of quantum mechanics become important. Quantum mechanics is the study of how subatomic particles (such as electrons, protons, and neutrons) behave. Subatomic particles do not always obey the same laws as large objects. Hence, the laws of quantum mechanics sometimes seem contrary to common sense. One rule of quantum mechanics (known as the Pauli exclusion principle) is this: Two identical electrons, located in the same region of space, cannot have the same velocity. In a dense white dwarf, where the electrons are packed close to each other, some of the electrons are forced to have high velocities, and hence provide a high pressure. In a degenerate object such as a white dwarf, the fast-moving high-energy electrons provide a pressure which is independent of temperature. Even as the temperature of a white dwarf falls toward absolute zero, the Pauli exclusion principle demands that the high-velocity electrons keep moving at the same speed. Hence, the pressure exerted by the electrons remains constant as the temperature falls." Erik --- kimharch(a)cut.net wrote: From: "Kim" <kimharch(a)cut.net> To: "'Utah Astronomy'" <utah-astronomy(a)mailman.xmission.com> Subject: Re: [Utah-astronomy] White dwarfs and YOU Date: Sun, 25 Jan 2009 17:55:28 -0700 Thanks, Chuck. Why, though, the extremely high temperatures? -----Original Message----- From: utah-astronomy-bounces(a)mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Sunday, January 25, 2009 5:49 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] White dwarfs and YOU They aren't using "burning" fuel at all any more. They are merely radiating residual energy. They are so small, that it takes billions of years for it to all radiate away. On Sun, Jan 25, 2009 at 5:36 PM, Kim <kimharch(a)cut.net> wrote: > can anyone succinctly describe for me the internal > processes that cause white dwarves to "burn" if it isn't nuclear fusion? > > _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com No virus found in this incoming message. Checked by AVG. Version: 7.5.552 / Virus Database: 270.10.13/1914 - Release Date: 1/24/2009 8:40 PM No virus found in this outgoing message. Checked by AVG. Version: 7.5.552 / Virus Database: 270.10.13/1914 - Release Date: 1/24/2009 8:40 PM _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

2 2

Re: [Utah-astronomy] We are fortunate
by zaurak＠digis.net 25 Jan '09

25 Jan '09

Be prepared for the strange look from the clerk. You have to ask for it, last time I bought some they kept it under the counter. I was advised to take it easy with it. Prior to that, during college, we would spike 16 gallon kegs with a quart of everclear, it was "high test" stuff --- jimgibson00(a)yahoo.com wrote: From: Jim Gibson <jimgibson00(a)yahoo.com> To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> Subject: Re: [Utah-astronomy] We are fortunate Date: Sun, 25 Jan 2009 17:16:09 -0800 (PST) Rich, I have been debating going to the state liquor store and purchasing some Everclear for mirror cleaning because my mirror is as you describe yours. Also my break squeeks and my spider needs a little tweak. Jim --- On Sun, 1/25/09, Richard Tenney <retenney(a)yahoo.com> wrote: From: Richard Tenney <retenney(a)yahoo.com> Subject: Re: [Utah-astronomy] We are fortunate To: "Utah Astronomy" <utah-astronomy(a)mailman.xmission.com> Date: Sunday, January 25, 2009, 5:20 PM Love to Jim. My mirror is in serious need of cleaning too, and I don't recall ever having had a peek through your TK. 20" IIRC...? --- On Sun, 1/25/09, Jim Gibson <jimgibson00(a)yahoo.com> wrote: > From: Jim Gibson <jimgibson00(a)yahoo.com> > Subject: Re: [Utah-astronomy] We are fortunate > To: "Utah Astronomy" <utah-astronomy(a)mailman.xmission.com> > Date: Sunday, January 25, 2009, 3:04 PM > Hey Rich! > > Thank you so much. > > Rich. Maybe when the weather gets better (seems a long way > off today) Maybe we can get together and we can tweak my > TeleKit a bit. > > Jim Gibson > > --- On Sun, 1/25/09, Richard Tenney > <retenney(a)yahoo.com> wrote: > > From: Richard Tenney <retenney(a)yahoo.com> > Subject: Re: [Utah-astronomy] We are fortunate > To: "Utah Astronomy" > <utah-astronomy(a)mailman.xmission.com> > Date: Sunday, January 25, 2009, 10:28 AM > > Not to mention A LOT of really wonderful human beings, like > Jim Gibson... > :o) > > > --- On Sun, 1/25/09, Jim Gibson > <jimgibson00(a)yahoo.com> wrote: > > > From: Jim Gibson <jimgibson00(a)yahoo.com> > > Subject: [Utah-astronomy] We are fortunate > > To: "Utah Astronomy" > <utah-astronomy(a)mailman.xmission.com> > > Date: Sunday, January 25, 2009, 7:50 AM > > > > My post about Chuck Hards and the Daves got me to > thinking > > how fortunate we are on this list. Another example > of an > > incredible person is Patrick Wiggins. One night just > for > > fun I Googled up Patrick Wiggins name and was > completely > > amazed at the number of different locations that > Patrick has > > been a contributor to. From what I could tell > Pratrick’s > > comments always demonstrated a high level of > understanding > > on several subjects and I could go on but it already > sound > > like a speech you hear before someone gets a metal or > > something. > > > > One of the many things I admire, envy even, about > Patrick > > is his ability to find and image things that are > > ephemeral. If I can find it I will try and post a > > photograph of the Columbia I took at Leeds (north of > St. > > George) as it passed over head and was beginning to > come > > apart. I never would have gotten that picture if it > > hadn’t been for Patrick’s direction. > > > > At any rate we have a lot of knowledgeable people on > this > > list. I could go on about Daniel Turner, Joe Bauman > and > > others but I better cut if off here. > > > > Jim Gibson > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > Utah-Astronomy mailing list > > Utah-Astronomy(a)mailman.xmission.com > > > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > > Visit the Photo Gallery: > http://gallery.utahastronomy.com > > Visit the Wiki: http://www.utahastronomy.com > > > > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > Visit the Photo Gallery: http://gallery.utahastronomy.com > Visit the Wiki: http://www.utahastronomy.com > > > > > _______________________________________________ > Utah-Astronomy mailing list > Utah-Astronomy(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > Visit the Photo Gallery: http://gallery.utahastronomy.com > Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

1 0

White dwarfs and YOU
by Chuck Hards 25 Jan '09

25 Jan '09

Would the plural of "white dwarf" be "white dwarves"? To the best of my knowledge, there are only 2 white dwarf stars within reach of the average visual amateur telescope. White dwarves are intrinsically very faint, meaning that we can only see those very close to the solar system. The brightest and closest is the companion of Sirius, although this can be a challenging observation since it is often lost in the glare of Sirius itself. The only other observable one is not too far from Sirius and in good position for viewing at this time of year. It is Omicron 2 Eridani B, also known as 40 Eridani B. Here is a finder chart. Omicron 2 Eridani is colored red on the chart, which is a section of the Skalnate Pleso atlas. Orion is easily discerned to the east (left) of the star, giving easy reference. http://www.slas.us/gallery2/main.php?g2_itemId=656 Alpha, the star you can see with your unaided eye, is mag. 4.4. The white dwarf itself, Omicron 2 Eridani B, is located 83" (seconds of arc) to the east-southeast of the alpha star and is mag. 9.5- much dimmer. There is a third star, C, only 9" to the north of B, but it is a red dwarf (common as houseflies!) at mag. 11.2. In the 2009 Observer's Handbook, page 309, Roy Bishop notes: "For the observer with a small telescope, Omicron 2 Eri B is the only earth-sized object visible in the depths of interstellar space, the only visible object with a mass density far exceeding that of ordinary matter, the only accessible star no longer powered by nuclear reactions, and the only star that has expired and can still be seen." Pretty cool! Neat stuff to contemplate as you gaze at it. How about one of you imagers getting a shot of the field and posting it? Who will post a visual impression?

5 18

Re: [Utah-astronomy] White dwarfs and YOU
by zaurak＠digis.net 25 Jan '09

25 Jan '09

Until they become a black dwarf, they start very hot and cool off during billions of years. --- chuck.hards(a)gmail.com wrote: From: Chuck Hards <chuck.hards(a)gmail.com> To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> Subject: Re: [Utah-astronomy] White dwarfs and YOU Date: Sun, 25 Jan 2009 17:48:35 -0700 They aren't using "burning" fuel at all any more. They are merely radiating residual energy. They are so small, that it takes billions of years for it to all radiate away. On Sun, Jan 25, 2009 at 5:36 PM, Kim <kimharch(a)cut.net> wrote: > can anyone succinctly describe for me the internal > processes that cause white dwarves to "burn" if it isn't nuclear fusion? > > _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

1 0

Re: [Utah-astronomy] White dwarfs and YOU
by zaurak＠digis.net 25 Jan '09

25 Jan '09

Hi Kim, I think what Chuck is saying that the early stage of the very hot young white dwarfs, that is heating the gas, is really an intermediate stage between the atypical red giant and a white dwarf. We can observe the nebula until the gas from the red giant "evaporates" I agree with what you are saying, in that the conventional thought is that it is "heat" from the white dwarf that makes the nebula visible. The article is saying that once it is not a red giant it is a white dwarf. I would be interested to see an article that explains that intermediate stage more clearly. It is likely a matter of semantics. I have also observed side by side with the "2 Daves" as much as anyone, I would agree most of the time I have seen the same thing, it gets sketchier with galaxy clusters. It would be a mistake to disagree, some people get very angry if you don't. At public star parties I keep my descriptions to the obvious, to avoid same kind of disappointment that comes from over hyping comets. If someone needs to describe what you are seeing are you really seeing it. I have processed about dozen Messier logs for the Astronomical League and no one describes every object the same, the same goes for double star logs, even the non colored ones. Erik --- kimharch(a)cut.net wrote: From: "Kim" <kimharch(a)cut.net> To: "'Utah Astronomy'" <utah-astronomy(a)mailman.xmission.com> Subject: Re: [Utah-astronomy] White dwarfs and YOU Date: Sun, 25 Jan 2009 17:36:31 -0700 I've enjoyed reading y'alls comments. As I mentioned some days ago regarding stellar colors, I rarely trust what I've read that others see - so it is with planetary nebula, central stars and other phenomena. When I've been observing side-by-side with keen observers like Dave Bernson and Dave Bennett, I've never had difficulty seeing what they see, but I admit I may not do so well on my own. I've always understood that the very hot radiation from a pn's central star was responsible for the excitement, and hence visibility, of the shell of matter surrounding the star, and that (only?) a white dwarf can generate the conditions necessary for that to occur. Hence, no white dwarf, no visible nebula. Have I been wrong? Also, since I don't have time to do some serious web-surfing right now, can anyone succinctly describe for me the internal processes that cause white dwarves to "burn" if it isn't nuclear fusion? Kim -----Original Message----- From: utah-astronomy-bounces+kimharch=cut.net(a)mailman.xmission.com [mailto:utah-astronomy-bounces+kimharch=cut.net@mailman.xmission.com] On Behalf Of zaurak(a)digis.net Sent: Sunday, January 25, 2009 4:38 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] White dwarfs and YOU Hi Chuck, I am far from expert, but that seem contrary to what Professor Ryden (Ohio State) says. She indicates the White Dwarf outlives the planetary nebula. As far as what can be seen visually, Zwicky seemed to push the envelope when he claimed he could visually detect motion in galaxy clusters. Most contemporaries thought him crazy, although time proved they do have motion. I am not sure this proves he could see the motion though. I think it easy to convince yourself you are seeing a central star after you have seen it once. I agree with Daniel that I have seen many stars in the center of many planetary nebula, with the Grim and they seem likely to be White Dwarfs. Bernson can describe many objects from memory, in detail, without looking through an eyepiece, I find myself not always seeing the detail he describes. I have noticed many at public star parties scratching their heads over details they are told they "should" be seeing. I tell people that the more you observe the more you will see, past experiences and views do matter. The 20" dob I observed with also yielded many central stars in planetary nebula. I have only observed the Messier Planetary Neb with smaller scopes, under very dark skies I recall seeing the central star of M57 with a 10-12" scope. Erik Quoting Ryden: "An asymptotic giant branch star (a red giant star which is about to run out of fuel) is not very stable. It undergoes thermal pulses during which the outer layers of the star are ejected into space. Finally, when the star totally exhasts it fuel supply, its core collapses and heats up. The core becomes a very hot white dwarf, with a surface temperature of 100,000 Kelvin, or more. The ejected outer layers, heated by the hot new white dwarf, form an emission nebula. An emission nebula of this sort - ejected gas which is being excited by a hot white dwarf - is called a planetary nebula. (This confusing name goes back to the 18th century; viewed through a small telescope, the fuzzy disk of a planetary nebula looks a bit like the fuzzy disk of a planet like Uranus. After the planetary nebula fades, the white dwarf will still be visible. White dwarfs shine because they are hot; although a white dwarf has no internal power source, it takes billions of years for a white dwarf to cool down. Thermal energy in the interior of a white dwarf is carried to the surface by conduction, then radiated away." --- chuck.hards(a)gmail.com wrote: From: Chuck Hards <chuck.hards(a)gmail.com> To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> Subject: Re: [Utah-astronomy] White dwarfs and YOU Date: Sun, 25 Jan 2009 16:06:40 -0700 The same can be said of your "central star" statement. From what I've been reading, now stellar evolutionists believe that the white dwarf stage isn't clearly reached until the planetary nebula has ceased to exist- an incredibly short lifespan of only a few tens to a hundred thousand years is typical for a planetary nebula. Central stars of visible planetaries are considered pre-white dwarf stars. The knowledge base continues to be refined as time passes. It may be that Bishop knows this but wanted to point out examples of stars unambiguously settled in the white-dwarf stage. Firmly in the stellar grave yard, with no evidence of recent nuclear reactions in the immediate environ. Bishop never made an absolute statement such as you imply; he mentioned no apertures at all. A 10" telescope isn't considered a small telescope by the general public- or with many serious amateurs. It's pretty big to me, and I've been doing this since 1968. Hair-splitting, semantic games can always be played with someone's words trying to communicate astronomy to a wide audience. Only a tiny fraction of people would jump on a soapbox and find issue with Bishop's exact choice of words. I wholeheartedly approve of Bishop's piece, and your statement does nothing to provide contrary evidence. On Sun, Jan 25, 2009 at 3:36 PM, daniel turner <outwest112(a)yahoo.com> wrote: > The problem comes when someone writes with a voice of authority about what > "can't be done". This causes people to immediately try to prove them wrong. > Bishop may regret his choice of words but it's best to remember that just > because you haven't seen something, doesn't mean the other people haven't > either or that next year they might be able to. > > I look at dozens of planetary nebula every year, and a large fraction of > these have an easily seen central star. Most can be seen with a 10" which > is no longer considered a particularly large telescope anymore. The > standards for an "amateur" or "backyard" or "average" telescope may continue > to change change with time. > > _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com No virus found in this incoming message. Checked by AVG. Version: 7.5.552 / Virus Database: 270.10.13/1914 - Release Date: 1/24/2009 8:40 PM No virus found in this outgoing message. Checked by AVG. Version: 7.5.552 / Virus Database: 270.10.13/1914 - Release Date: 1/24/2009 8:40 PM _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

1 0

Re: [Utah-astronomy] White dwarfs and YOU
by zaurak＠digis.net 25 Jan '09

25 Jan '09

Hi Chuck, I am far from expert, but that seem contrary to what Professor Ryden (Ohio State) says. She indicates the White Dwarf outlives the planetary nebula. As far as what can be seen visually, Zwicky seemed to push the envelope when he claimed he could visually detect motion in galaxy clusters. Most contemporaries thought him crazy, although time proved they do have motion. I am not sure this proves he could see the motion though. I think it easy to convince yourself you are seeing a central star after you have seen it once. I agree with Daniel that I have seen many stars in the center of many planetary nebula, with the Grim and they seem likely to be White Dwarfs. Bernson can describe many objects from memory, in detail, without looking through an eyepiece, I find myself not always seeing the detail he describes. I have noticed many at public star parties scratching their heads over details they are told they "should" be seeing. I tell people that the more you observe the more you will see, past experiences and views do matter. The 20" dob I observed with also yielded many central stars in planetary nebula. I have only observed the Messier Planetary Neb with smaller scopes, under very dark skies I recall seeing the central star of M57 with a 10-12" scope. Erik Quoting Ryden: "An asymptotic giant branch star (a red giant star which is about to run out of fuel) is not very stable. It undergoes thermal pulses during which the outer layers of the star are ejected into space. Finally, when the star totally exhasts it fuel supply, its core collapses and heats up. The core becomes a very hot white dwarf, with a surface temperature of 100,000 Kelvin, or more. The ejected outer layers, heated by the hot new white dwarf, form an emission nebula. An emission nebula of this sort - ejected gas which is being excited by a hot white dwarf - is called a planetary nebula. (This confusing name goes back to the 18th century; viewed through a small telescope, the fuzzy disk of a planetary nebula looks a bit like the fuzzy disk of a planet like Uranus. After the planetary nebula fades, the white dwarf will still be visible. White dwarfs shine because they are hot; although a white dwarf has no internal power source, it takes billions of years for a white dwarf to cool down. Thermal energy in the interior of a white dwarf is carried to the surface by conduction, then radiated away." --- chuck.hards(a)gmail.com wrote: From: Chuck Hards <chuck.hards(a)gmail.com> To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> Subject: Re: [Utah-astronomy] White dwarfs and YOU Date: Sun, 25 Jan 2009 16:06:40 -0700 The same can be said of your "central star" statement. From what I've been reading, now stellar evolutionists believe that the white dwarf stage isn't clearly reached until the planetary nebula has ceased to exist- an incredibly short lifespan of only a few tens to a hundred thousand years is typical for a planetary nebula. Central stars of visible planetaries are considered pre-white dwarf stars. The knowledge base continues to be refined as time passes. It may be that Bishop knows this but wanted to point out examples of stars unambiguously settled in the white-dwarf stage. Firmly in the stellar grave yard, with no evidence of recent nuclear reactions in the immediate environ. Bishop never made an absolute statement such as you imply; he mentioned no apertures at all. A 10" telescope isn't considered a small telescope by the general public- or with many serious amateurs. It's pretty big to me, and I've been doing this since 1968. Hair-splitting, semantic games can always be played with someone's words trying to communicate astronomy to a wide audience. Only a tiny fraction of people would jump on a soapbox and find issue with Bishop's exact choice of words. I wholeheartedly approve of Bishop's piece, and your statement does nothing to provide contrary evidence. On Sun, Jan 25, 2009 at 3:36 PM, daniel turner <outwest112(a)yahoo.com> wrote: > The problem comes when someone writes with a voice of authority about what > "can't be done". This causes people to immediately try to prove them wrong. > Bishop may regret his choice of words but it's best to remember that just > because you haven't seen something, doesn't mean the other people haven't > either or that next year they might be able to. > > I look at dozens of planetary nebula every year, and a large fraction of > these have an easily seen central star. Most can be seen with a 10" which > is no longer considered a particularly large telescope anymore. The > standards for an "amateur" or "backyard" or "average" telescope may continue > to change change with time. > > _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy(a)mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com

4 6