APOD: J102815: A Star That Should Not Exist (2011 Sep 07)

Post a reply


This question is a means of preventing automated form submissions by spambots.
Smilies
:D :) :ssmile: :( :o :shock: :? 8-) :lol2: :x :P :oops: :cry: :evil: :roll: :wink: :!: :?: :idea: :arrow: :| :mrgreen:
View more smilies

BBCode is ON
[img] is ON
[url] is ON
Smilies are ON

Topic review
   

Expand view Topic review: APOD: J102815: A Star That Should Not Exist (2011 Sep 07)

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by khearn » Tue Dec 13, 2011 6:56 pm

I'm coming into this discussion very late, and I apologize for being off-topic and discussing the star, not the language usage.

It occurs to me that this star is somewhat similar to Earth's moon. Both are lacking in expected heavy elements. Might they have had similar origins? Could the collision (or near collision) of two stars have caused enough material from the outer layers of the stars to be expelled, so that a new star could form from it? This material from the outer layers of the stars would likely me almost all hydrogen and helium, since the heavier elements would be concentrated near the cores of the stars. Two very large stars passing close to each other would probably draw off tidal tails, similar to two galaxies passing close to each other. If the stars are big enough, could the material draw off could be sufficient to form a new, small, and metal-deficient star?

I know such a collision is incredibly unlikely, but the universe is a big place, so even very unlikely things are likely to have happened.

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by starman » Sat Sep 17, 2011 2:32 pm

Lithium is actually the signature of a very young star, since once the core fusion process kicks off, Li is rapidly destroyed. So, find Li in a star's spectrum and you've got a YSO.
Incidentally, as an honours graduate in English/Linguistics, I think all this faffing about with Fewer/Less is an irrelevancy. "Fewer" is, on the basis of usage, rapidly becoming redundant (at least here in the UK). The meaning is absolutely clear - "not so much as", "a smaller quantity than", etc. It's just pedantry in the same class as 'you should never split infinitives' or 'never end a sentence with a preposition'.

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by mst66186 » Thu Sep 08, 2011 5:14 am

Iron Sun 254 wrote:
mst66186 wrote:
APOD Robot wrote:... Furthermore, even the elusive never-seen first stars in the universe, so-called Population III stars, are predicted to have a large mass and a small but set amount of heavy elements. ...
Ummm... from following the links it seems that our sun would be a generation III star and these elusive never-seen first stars should be Population I?
Population I is is not a term for first generation stars but for the youngest generation. They were named in order of discovery so, since our Sun was obviously in the first group to be discovered, that group was designated Population I.
OK. Thanks for the info. I got confused because of the text "Our own Sun is thought to be a third generation star, with many second-generation stars seen in globular clusters" on the page behind the link 'Population III'. I agree it's important for one to 'say what you mean and mean what you say'!

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by Chris Peterson » Thu Sep 08, 2011 4:39 am

Wolf kotenberg wrote:The ' soup " i mentioned earlier was just a moniker I used to describe the mixture. I could have just as easily described it as a mixture of 25% helium plus 75% hydrogen but do you have any idea how long it takes me to rtype that ?
Nobody has created sustained fusion at all in a laboratory, so there is no "experimental" model for a star, except via numerical simulation.

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by Wolf kotenberg » Thu Sep 08, 2011 4:14 am

The ' soup " i mentioned earlier was just a moniker I used to describe the mixture. I could have just as easily described it as a mixture of 25% helium plus 75% hydrogen but do you have any idea how long it takes me to rtype that ?

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by Chris Peterson » Thu Sep 08, 2011 3:25 am

drollere wrote:thanks, chris. as a visual astronomer i guess i work in a shallower pond. what then is a "faint" star -- mag. 20? how many stars are available to scrutiny in the SDSS survey? i see cites to only about 250,000 under two project headings.
Mag 19 is faint for SDSS spectroscopy, mag 23 is faint for SDSS imaging. Data release 7, which was used by these researchers, has about a half million stellar spectra. With the data release 8 this year, that number is now much higher.
yes, but there is a lot of handwaving about how it all works ... fiber optics, CCDs, computers, poof! 3000 stars. does SDSS have a paper on the actual processes?
There's a lot of good information on the SDSS site... I wouldn't call it "handwaving". Spectroscopic data is collected with a fairly standard survey tool, consisting of custom drilled plates matching stellar fields, which apertures connected via fiber optic to a spectrograph. The instrument is described here.

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by Boomer12k » Thu Sep 08, 2011 1:49 am

25% Helium....so it talks in a high, squeaky voice????

:-------======== *

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by drollere » Thu Sep 08, 2011 12:52 am

Chris Peterson wrote:At around mag 17, this star would generally be considered pretty bright. It is orders of magnitude brighter than the SDSS detection limit.
thanks, chris. as a visual astronomer i guess i work in a shallower pond. what then is a "faint" star -- mag. 20? how many stars are available to scrutiny in the SDSS survey? i see cites to only about 250,000 under two project headings.
As the paper notes, the researchers identified nearly 3000 stars ...
yes, but there is a lot of handwaving about how it all works ... fiber optics, CCDs, computers, poof! 3000 stars. does SDSS have a paper on the actual processes?

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by islader2 » Wed Sep 07, 2011 11:02 pm

@ NEUFER. There has been enough nitpicking on today's Asterisk to last forever. But, humbly, I must comment on the photo of General Petraeus and the "fruit salad" on his tunic==since I have worn some of the same "salad." Some is medal bars==some is awards. I would hate think that I was medaled for being in combat as a foot-soldier, or for being a paratrooper. Those are awards that we wear proudly==not service ribbons. Thanx. :!: :!: :!: :!:

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by islader2 » Wed Sep 07, 2011 10:31 pm

@ owlice==Your contributions to this "blog" are too valuable to have you involved, crabbily, with some of our less-astronomy minded posters. Your nom-de-plume is bound to arouse other solons to enter into an unworthy discussion of semantics and grammar. I liked it better when you directed newcomers to the rules for posting. Thanx. :D :D :D

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by Chris Peterson » Wed Sep 07, 2011 9:22 pm

Wolf kotenberg wrote:Has this particular " soup " been duplicated in a lab ? Is this more like water and oil of more like smoke and air ?
What "soup" are you referring to?

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by Wolf kotenberg » Wed Sep 07, 2011 9:10 pm

Has this particular " soup " been duplicated in a lab ? Is this more like water and oil of more like smoke and air ?

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by Chris Peterson » Wed Sep 07, 2011 8:20 pm

drollere wrote:this star is very faint ... i cannot find it in the millennium star atlas, not even in stellarium, so it must be below v.mag. 15.
At around mag 17, this star would generally be considered pretty bright. It is orders of magnitude brighter than the SDSS detection limit.
my question is how it was identified in the first place, given the time required for even a large aperture scope to collect enough light to do the detailed spectroscopy.
It was detected by the SDSS, which amongst other data provides information that can be used to infer metallicity. As the paper notes, the researchers identified nearly 3000 stars in the SDSS data that were candidates for close examination, which they then narrowed down by visibility and other factors, performing spectroscopy on six before settling on this particular star.

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by flash » Wed Sep 07, 2011 8:18 pm

On LESS vs FEWER (my view):

The important distinction is whether the variables being compared are DISCRETE or CONTINUOUS. When comparing the NUMBER of elements present "FEWER" is the correct word. On the other hand when comparing the relative abundance of heavy or light elements, then LESS is correct word. Similarly, when comparing energy content of two items, it is correct to say FEWER calories. not LESS calories. But it is also correct to say LESS energy, but certainly not FEWER energy. On the plus side, MORE works for both discrete and continuous variables. Hope this helps!

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by NoelC » Wed Sep 07, 2011 7:32 pm

One has to wonder if there are any natural processes that throughout the eons might have resulted in everything heavier than hydrogen being drawn away (e.g., by gravity), then finally a star formed from the purified gas.

We simply can't presume to know all the processes that can take (or have taken) place out in the wild, wonderful universe.

-Noel

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by drollere » Wed Sep 07, 2011 6:54 pm

this star is very faint ... i cannot find it in the millennium star atlas, not even in stellarium, so it must be below v.mag. 15. my question is how it was identified in the first place, given the time required for even a large aperture scope to collect enough light to do the detailed spectroscopy. assuming that similar data were collected for the millions of stars at or below that magnitude, seriously clever computation was necessary to sort this spectrum out of the huge pile. i'd certainly like to know more about that.

re the syntactic cat fight: i don't mind stress tests of english grammar, because our grammar is wonderfully flexible and expressive; but i think the writer could benefit from less reliance on the digressive comma, and more effort at arranging ideas into a linear flow.

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by Chris Peterson » Wed Sep 07, 2011 4:52 pm

casubellus wrote:How about this "theory": there is a vast amount of nearly-impossible-to-detect MOLECULAR hydrogen in interstellar and inter-galactic space, which allows this type of star to form AND accounts for the (non existent) 'dark matter'. :)
Molecular hydrogen makes up most of the interstellar medium; the problem with this star is that it contains only hydrogen and helium. The modern ISM is "contaminated" with heavier elements, so why don't these show up in an apparently new star?

Molecular hydrogen is, of course, ordinary baryonic matter, which means it isn't a candidate for dark matter. The dynamics of dark matter makes it clear that it doesn't interact with ordinary matter, so it must be something quite different.

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by bystander » Wed Sep 07, 2011 3:39 pm

Why does this star have so few heavy elements?
... the stars that created most of the heavy elements around us today, are seen to have some, although less, elements heavier than H and He ...
... low-mass Milky Way star SDSS J102915+172927, among others, appears to have less metals than ever predicted for any stars ...
I think the objection was to your use of less instead of fewer, not few instead of less.

In any case, I support your choice of comparatives, and join you in being willfully illiterate. :)

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by RJN » Wed Sep 07, 2011 3:20 pm

Why does this star have so few heavy elements?
After some thought, I have decided to stick with the word "few" and to try to weather the storm. One reason is that substituting the word "less" just doesn't sound right to me. Putting in "less" would have the reader demanding to know "less than what?" and feel frustrated when that question is not answered right in the next sentence. Now surely the word "few" is also comparative, but I think less so -- in my mind it does not bring up the phrase "fewer than what" as strongly. Sometimes when I write (OK,"type in words" might be more accurate), I try to create a flow of thoughts in the readers mind. Here the word "less" does not create as good a flow as "few", in my opinion. Were the words exactly equal in meaning and flow and the only problem being one of grammatical correctness, I would make the change. I apologize if this disappoints and convinces many that I am not only illiterate, but willfully so.

- RJN

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by bystander » Wed Sep 07, 2011 3:20 pm

Iron Sun 254 wrote:
mst66186 wrote:
APOD Robot wrote:... Furthermore, even the elusive never-seen first stars in the universe, so-called Population III stars, are predicted to have a large mass and a small but set amount of heavy elements. ...
Ummm... from following the links it seems that our sun would be a generation III star and these elusive never-seen first stars should be Population I?
Population I is is not a term for first generation stars but for the youngest generation. They were named in order of discovery so, since our Sun was obviously in the first group to be discovered, that group was designated Population I.
See Wikipedia: Metallicity: Populations III, II, and I

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by saturn2 » Wed Sep 07, 2011 2:47 pm

The J 102815 star look like to human organism.
This star has 75% of H and 25% others elements.
The human organismo has 75% de H2O and 25% others elements.
J 102815 is a star that shoud not exist, but it exist.
I think that BIG BANG theory has many errors.
Other example of error of the Big Bang theory is the far explotion of object GRB 090423

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by Iron Sun 254 » Wed Sep 07, 2011 2:21 pm

mst66186 wrote:
APOD Robot wrote:... Furthermore, even the elusive never-seen first stars in the universe, so-called Population III stars, are predicted to have a large mass and a small but set amount of heavy elements. ...
Ummm... from following the links it seems that our sun would be a generation III star and these elusive never-seen first stars should be Population I?
Population I is is not a term for first generation stars but for the youngest generation. They were named in order of discovery so, since our Sun was obviously in the first group to be discovered, that group was designated Population I.

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by bystander » Wed Sep 07, 2011 1:18 pm

English Adept wrote:Whoever wrote this, if English is their first language, should be ashamed. :roll: The first sentence should read "...are seen to have some, although fewer, elements..." The second should be "...appears to have fewer metals..."
reedkantor wrote:thats "fewer"metals, not "less metals." grammar is important when writing...know the difference between the use of "fewer" and "less." muchas gracias.
Axel wrote:... it [is] less of one thing and fewer of a number of things.
We are talking about one thing, metals, a mass noun meaning elements heavier than hydrogen or helium. Substitute metallic content or metallicity, if you wish, but less is appropriate, not fewer.
Ann wrote:Well, as a non-native English speaker it seems to me that there might be a difference between "fewer metals" and "less metals". "Fewer metals" might mean that the spectrum of a star shows evidence of only, say, three elements apart from hydrogen and helium. "Less metals" might mean that the elements apart from hydrogen and helium exist in extremely low amounts.
English Adept wrote:Ann, that's not how it works. It's two different forms of the same meaning (fewer versus less). If the second meaning you suggest was intended, it should be stated as "lower amounts of metals", or something similar.
Actually, that's exactly how it works and Ann is correct in her interpretation. As stated above, metals, as used here, is a mass noun, much like water. The statement, "Because of the drought, there is fewer water in the lake." is absolutely nonsensical, yet that is the usage you advocate.

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by nstahl » Wed Sep 07, 2011 1:01 pm

neuter thanks for pointing out so graphically the difference between "fewer metals" and "less metals", and the sense in which "less metals" can be considered correct here. And since it can be considered correct I really think the benefit of any doubt one has should go to the people who spend so much effort putting this up every day. And in this case if one has no doubt it's because one hasn't thought it through.

Re: APOD: J102815: A Star That Should Not Exist (2011 Sep 07

by neufer » Wed Sep 07, 2011 12:57 pm

orin stepanek wrote:
I would think to destroy the lithium; the star must of been in a state of fission instead of fusion!
:? That doesn't seem to work for me!
Image
Lithium citrate
Perhaps J102815 is just loaning its supply of lithium to
a nearby White Dwarf that is attempting to go all supernova on it.
http://en.wikipedia.org/wiki/Lithium_%28medication%29 wrote:
<<Lithium possesses a very important antisuicidal effect not shown
in other stabilizing medications such as antiseizures drugs.>>

Top