[meteorite-list] Vesta, for sure?
Hi Listthis is a completely neophyte question, so please accept my ignorance in things astronomicand allow me to ask you experts: I have always wondered why Vesta is the parent-body-de-jur for our HEDs, when so many unfound asteroids are no doubt cruizing around out there. Hence my question: Have any asteroids been paired yet, and if not, why Vesta alone gets the credit; as well, couldn't our HED cousins be cousins from a yet-to-be-discovered asteroid pairing? As you true scientists of course recognize, I'm completely green in this area. I guess it's my timeless query (X-factors-we-need-to consider) that has me bewildered. Has Vesta somehow distinguished itself as the one-and-only parent-body? I do understand reflection technology has identified our HED meteorites to be from Vesta, but why not an undiscovered twin? Or many multiple twins? With deference to those of you already in the know, Richard Montgomery - Original Message - From: lebof...@lpl.arizona.edu To: Michael Gilmer meteoritem...@gmail.com Cc: meteorite-list@meteoritecentral.com; Shawn Alan photoph...@yahoo.com Sent: Thursday, April 07, 2011 4:39 PM Subject: Re: [meteorite-list] List of meteorites from Vesta? Hi Michael: Yes, there is a smoking gun and a trail of dust, too. Reflectance spectra of Vesta and areas of Vesta consistent with spectra of HED meteorites and composition of HEDs. Big crater that could be the source of said meteorites. Vestoids in an area where asteroids can be tossed out of the asteroid belt into Earth-crossing orbits. Vestoids IN Earth-crossing orbits. Short of a sample return, not sure what more evidence you need (smoking gun but not a confession). Larry Hi Shawn, Larry, and Expat Vestans, I included Dunite in my answer to Regine's question because I wanted to be all inclusive. Of course, the old axiom of damned if you, damned if you don't comes into play here. Had I left out Dunite, someone would have inevitably suggested it. Since I included it, the inevitable question of whether or not it actually belongs was brought up. This highlights the uncertainty inherent in theorizing about other worlds that we lack first-hand knowledge of. Even the widely-accepted HED's are theoretically assigned to Vesta. There is no smoking gun yet that any meteorite originates from Vesta - at least that is my understanding of the HEDO group. But, so much circumstantial evidence points to Vesta, that it is generally agreed upon to be the parent body of the HEDO group. I don't think anyone is expecting the Dawn mission to disprove this theory. Everyone expects Dawn to confirm what the circumstantial evidence has implied - that the HEDO group is truly Vestan. While olivine diogenite may not appear in the official classification tree, NWA 1877 is classified as diogenite-an (of which, there are only two approved as such). There other is Grosvenor Mountains 9, which is described in the write-up as diogenite-unique, but looks like an olivine diogenite. Note, there is at least one possible pairing to NWA 1877 floating around and NWA 6149 comes to mind. (although the latter may not be officially paired yet) Note, NWA 6149 (and 5 others) are classified as diogenite-olivine - 3 of the others are NWA and one is Antarctic. The earliest apparent classification for this type (that appears in the Bulletin) is NWA 5603. (2004) Best regards, MikeG -- Mike Gilmer - Galactic Stone Ironworks Meteorites Website - http://www.galactic-stone.com Facebook - http://www.facebook.com/galacticstone News Feed - http://www.galactic-stone.com/rss/126516 Twitter - http://twitter.com/galacticstone EOM - http://www.encyclopedia-of-meteorites.com/collection.aspx?id=1564 --- On 4/7/11, Shawn Alan photoph...@yahoo.com wrote: Larry and Listerites Thank you Larry for the links. But I think my question is still unanswered or it hasn't been directly spelled out, which I am that type of person that needs it all. I do not see Olivine diogenite, and Dunite on the classification menu on the Meteoritical Bulletin Database (MBD) which is the BIBLE of all bibles when it comes to classification of meteorites. So what I am gathering at this time is that these two classes or sub or non at this time are not recognized by the MBD as a classification. Am I right? If it was wouldn't it be listed on the MBD as one. So do this mean its a subclass or something else. I have heard from some that dunites are not a meteorite classification. I have to believe that statement could be true because I don't see dunites coming up on the MDB classification menu or Olivine diogenites. By chance who coined these quote un quote classifications and why haven't they been listed on the MBD. I find it odd, but again I have seen a few meteorites get these weird names or nick names to create
[meteorite-list] Vesta, for sure?
Hi List...this is a completely neophyte question, so please accept my ignorance in things astronomic...and allow me to ask you experts: I have always wondered why Vesta is the parent-body-de-jur for our HEDs, when so many unfound asteroids are no doubt cruizing around out there. Hence my question: Have any asteroids been paired yet, and if not, why Vesta alone gets the credit; as well, couldn't our HED cousins be cousins from a yet-to-be-discovered asteroid pairing? As you true scientists of course recognize, I'm completely green in this area. I guess it's my timeless query (X-factors-we-need-to-consider) that has me bewildered. Has Vesta somehow distinguished itself as the one-and-only parent-body? I do understand reflection technology has identified our HED meteorites to be from Vesta, but why not an undiscovered twin? Or many multiple twins? With deference to those of you already in the know, Richard Montgomery __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Vesta, for sure?
Very good question Richard, which doesn't get explored often enough. Harry Hap McSween wrote a book titled Meteorites and their Parent Bodies where extensive spectral measurements were taken from meteorites and from asteroids and an extensive list of possible and probable asteroidal connections were given for many of the meteorites in our world collection. (BTW He also wrote much about transport theory to Earth) Several other scientists have followed with more research in the past decade and there is a conscientious that HEDs do come from Vesta or its fragmented daughters. My personal opinion is that the Vesta-HED connection is perhaps taken too literally at times, but going back far enough-- all HEDs do come from Vesta-- before it lost a part of its mass about 1 billion years ago in a big wack. The mineralogy we see today was from an intact planetary/differentiated body One would think for meteorites which are regolyths-- ( e.g. Howardites) we would have sampled many more asteroid bodies ( Ceres etc) and, it is very likely that we have sampled (via meteorite) some parent bodies which no longer exist: collision accretion, ejection etc and would not have any spectral measurements to compare them to. Here is one of many abstracts regarding 4 Vesta which discuss the probability HEDs are from Vesta or the 20 small bodies with similar spectra. Chips off of Asteroid 4 Vesta: Evidence for the Parent Body of Basaltic Achondrite Meteorite http://www.sciencemag.org/content/260/5105/186.abstract For more than two decades, asteroid 4 Vesta has been debated as the source for the eucrite, diogenite, and howardite classes of basaltic achondrite meteorites. Its basaltic achondrite spectral properties are unlike those of other large main-belt asteroids. Telescopic measurements have revealed 20 small (diameters ≤ 10 kilometers) main-belt asteroids that have distinctive optical reflectance spectral features similar to those of Vesta and eucrite and diogenite meteorites. Twelve have orbits that are similar to Vesta's and were previously predicted to be dynamically associated with Vesta. Eight bridge the orbital space between Vesta and the 3:1 resonance, a proposed source region for meteorites. These asteroids are most probably multikilometer-sized fragments excavated from Vesta through one or more impacts. The sizes, ejection velocities of 500 meters per second, and proximity of these fragments to the 3:1 resonance establish Vesta as a dynamically viable source for eucrite, diogenite, and howardite meteorites. Perhaps it is simply a matter of the postman's route and Vesta et.al. is the only candidate with the orbital dynamics to make deliveries to our sector of the solar system. To answer your question specifically-- the answer is Vesta is the only source--unless hypothedical twin was one of those early solar system bodies no longer with us. The size of Vesta is necessary to produce the variety of mineralogy we see in the HEDs. It had to be large enough to generate basalt/differentiation and also possess enough gravity to sort the mineralogy into layers akin to crust , mantle(s), and (probably) core AND it would also have to have a huge crater which excavated it down to the deep /lower mantle. So far as I know there is nothing else that can fill the bill. Safe to say ,all the larger asteroids in the inner solar system have been identified. Elton - Original Message From: Richard Montgomery rickm...@earthlink.net To: lebof...@lpl.arizona.edu; Michael Gilmer meteoritem...@gmail.com Cc: meteorite-list@meteoritecentral.com; Shawn Alan photoph...@yahoo.com Sent: Thu, April 7, 2011 9:09:46 PM Subject: [meteorite-list] Vesta, for sure? Hi Listthis is a completely neophyte question, so please accept my ignorance in things astronomicand allow me to ask you experts: I have always wondered why Vesta is the parent-body-de-jur for our HEDs, when so many unfound asteroids are no doubt cruizing around out there. Hence my question: Have any asteroids been paired yet, and if not, why Vesta alone gets the credit; as well, couldn't our HED cousins be cousins from a yet-to-be-discovered asteroid pairing? As you true scientists of course recognize, I'm completely green in this area. I guess it's my timeless query (X-factors-we-need-to consider) that has me bewildered. Has Vesta somehow distinguished itself as the one-and-only parent-body? I do understand reflection technology has identified our HED meteorites to be from Vesta, but why not an undiscovered twin? Or many multiple twins? With deference to those of you already in the know, Richard Montgomery __ Visit
Re: [meteorite-list] Vesta, for sure? part 2
The wikipedia articles linked below fit very well with Richards question as well as the discussion of dunite and olivine diogenites. It also removes my caveat about ejected body in my last message by stating that a candidate Diogenite-like asteroid unrelated to Vesta has been identified which may be from a differentiated body no longer with us. 1459 Magnya: Orbits in the outer main belt, too far from Vesta to be genetically related. May be the remains of a different ancient differentiated body that was shattered long ago. Another candidate for a dunite or olivine diogenite is: 2579 Spartacus — contains a significant portion of olivine, which may indicate origin deeper within Vesta than other V-types. See list at: http://en.wikipedia.org/wiki/V-type_asteroid http://en.wikipedia.org/wiki/4_Vesta 2 Pallas is a large and most certainly differentiated body but lacks evidence of an excavation and its spectrum shows carbonaceous chondriteaffinities Elton - Original Message From: Richard Montgomery rickm...@earthlink.net To: Meteorite-list List meteorite-list@meteoritecentral.com Sent: Thu, April 7, 2011 9:42:30 PM Subject: [meteorite-list] Vesta, for sure? Hi List...this is a completely neophyte question, so please accept my ignorance in things astronomic...and allow me to ask you experts: I have always wondered why Vesta is the parent-body-de-jur for our HEDs, when so many unfound asteroids are no doubt cruizing around out there. Hence my question: Have any asteroids been paired yet, and if not, why Vesta alone gets the credit; as well, couldn't our HED cousins be cousins from a yet-to-be-discovered asteroid pairing? As you true scientists of course recognize, I'm completely green in this area. I guess it's my timeless query (X-factors-we-need-to-consider) that has me bewildered. Has Vesta somehow distinguished itself as the one-and-only parent-body? I do understand reflection technology has identified our HED meteorites to be from Vesta, but why not an undiscovered twin? Or many multiple twins? With deference to those of you already in the know, Richard Montgomery __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
