From sylvio@usp.br Tue Oct 26 16:10:29 2004 Date: Tue, 19 Oct 2004 15:57:42 -0300 From: Sylvio Ferraz Mello Reply-To: sylvio@astro.iag.usp.br To: mira@sirrah.troja.mff.cuni.cz, Roig Dear Mira Dear Fernando You find below my report on your joint Belgrado paper. I have one suggestion for future investigation: Could the Griquas be "leaking" into the Zhongguos region due to Yarkovsky effect? If this would happen, the Griquas would be depleted of their smaller bodies while the Zhongguos would be enriched in small bodies, making easier to understant the respectively low and high steepness of the SFD. I would be glad colaborating to solve this question as far as possible. I would like to ear your preliminary opinion on the suggestion Sylvio -------------------------------------------------------------- Sylvio Ferraz Mello IAG-Universidade de Sao Paulo Rua do Matao, 1226 | phone +55-11-3091-2825 Cidade Universitaria | (Secretary 3091-2710) 05508-900 Sao Paulo | FAX +55-11-3091-2860 Brasil | e-mail sylvio@usp.br http://www.astro.iag.usp.br/~sylvio/ ---------------------------------------------------------------- IAU Colloquium 197 Report on the paper by M.Broz et al. This paper should be published after a minor revision. Main Comments. The introduction. -- The paper starts with a very biased story if the 2/1 resonance studies which should be revised, mainly because the present contribution is itself inserted into a completely different development that started with the paper that I presented in the ACM-1993 meeting (IAU Symposium 160). That paper showed, for the first time that, if Saturn is taken in full account, there the regions inside the 2/1 resonance become strongly chaotic. At the same meeting, one today forgot paper by H.Scholl showed the first simulations starting in the core of the 2/1 resonance and going to eccentricities higher than 0.8. Broz should be a kid a that time, but Morbidelli was there and certainly remembers that I failed to be thrown away through the windows at the end of my presentation ... For parts of the story that followed that event, please see the introduction of the papers Ferraz-Mello et al. and Roig et al. quoted in this paper. To complete this peroration let me remember that the papers published prior to that date (Henrard, Murray) were unable to show the main phenomena of the Kirkwood 2/1 gap because an incomplete model (3-body) and an inadequate representation of the disturbing forces (valid only in small eccentiricities). So, they were just able to find the chaos on the border of the resonance and at the low eccentricities (below the region B of Nesvorny & SFM). The papers by Morbidelli and Moons did introduce the secular perturbations of the orbit of Jupiter and were able to show the location of the main secular resonances. Several papers on the subject were published with our participation before the brilliant Ph.D. theses of Nesvorný and Roig. I invite the authors to pay attention to correct the distortions seen in the introduction. On the other hand, more important than split the papers in semi-analytic or numerical, would be to split them following the models they have used: pure 3-body > 3-body with secular perturbations > 4-body > N-body. This would be more interesting for the readers. Regions A and B -- They are mentioned in the abstract and in several parts of the paper. The reader not acquainted with the previous works will not be able to undestand what it means. The nomenclature should not be used in the abstract (or, at least, used cautiously), and in the thext they should be accompanied of the mention "(see fig. 4)" (and the letter B should be added to fig. 4). page 2. Griquas residing on semi-stable orbits ... The adjective semi-stable is not necessary to understand what is being said (it sounds to me as funny as semi-pregnant) In all figures, the authors use the axis titles in the form: magnitude/unit. This is not standard usage and is at the first sight confusing because the signe (/) has another meaning. OK, we don not need more than a few seconds to realize that what comes after (/) is the unit. But, why do not use the standard form: magnitude (unit)? Figure 5. I am not able to understand the "arrows" in the leftmost plot (and the last sentence in the caption). Page 6 (footnote): what means "the arbitrary division at 1 Gy"? Page 7 - Table 1 - It would be nice to have one more column indicating if it is a Griqua or a Zhongguo (letters, G,Z). I agree that it is enough to look at T_J2/1 to know it, but this can only be done if we have read carefully what precedes. Page 7 - There are two points in the discussion that deserves to be mentioned in this report: 1) To use the ratio A-Zhongguos/B-Zhongguos to make a point is hazardous (and will continue to be hazardous for a long time). New discoveries and/or new orbits will make this ratio change a lot. that ratio has no statistical signification because the number of A-Zhongguos is too small. 2) The discussion on steepness is OK while we only consider the unstable asteroids and the Griqua ones. But can not be extended to the Zhongguos! I think that to point the problem is relevant, but the Zhoingguos anomalous distribution shows that we cannot be too affirmative when discussing the others. Minor points: The logical symbol (/\) is not known to everybody and should not be used. At the last line of the abstract it should be high-eccentricity (higher is comparative, and no comparison is being made there). Footnotes. It is better to use the \footnote LaTeX command without forcing a symbol (the dagger). LaTeX will put numbers in that case and the risk of having two footnotes with the same symbol in the same page (as occurs now in page 8) will be discarded. Caption of fig. 2 - line 5. Missing verb: "... while others ARE short-lived."