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The R.A.P. Project (Reviews of Astro-Ph)

Dinamika, mehanika i t.p.
(Arhiv Dinamika:
v.2, 2003, v.1, 2002-2003)

Vypusk 201. 01-16 dekabrya 2008

obzor arxiv:0812.2610 Statisticheskaya mehanika gravitiruyushih sistem: obzor (Statistical mechanics of gravitating systems: an overview)
Authors: T. Padmanbhan
Comments: 25 pages, Les Houches summer school

Poleznyi obzor-lekciya po metodam statisticheskogo opisaniya sistem tipa skopleiya chastic, svyazannyh vzaimnym tyagoteniem. Privodyatsya formuly i dlya sluchaya rasshiryayushegosya prostranstva.


Vypusk 192. 01-14 avgusta 2008

obzor arxiv:0808.0203 Uglovoi moment galaktik i ego korrelyacii (Review: galactic angular momenta and angular momentum correlations in the cosmological large-scale structure)
Authors: Bjoern Malte Schaefer
Comments: 22 pages, 7 figures, invited review for IJMPD

Galaktiki priobretayut uglovoi moment za schet prilivnyh vozdeistvii v processe formirovaniya krupnomasshtabnoi struktury. Razumeetsya, parametry vrasheniya okazyvayut skorrelirovany s drugimi parametrami galaktik i okruzhayushih ih struktur. Vse eto tak ili inache mozhet proyavlyat'sya v nablyudeniyah (v chastnosti, v dannyh po linzirovaniyu). Vsemu etomu i posvyashen dannyi obzor. Napisano otnyud' ne prosto.


Vypusk 183. 01-20 aprelya 2008

arxiv:0804.1946 K voprosu o dinamicheskoi ustoichivosti Solnechnoi sistemy (On the Dynamical Stability of the Solar System)
Authors: Konstantin Batygin, Gregory Laughlin
Comments: 37 pages, 18 figures, accepted for publication in the Astrophysical Journal

Avtory chislenno issleduyut dinamicheskuyu ustoichivost' Solnechnoi sistemy na bol'shih vremenah (milliardy let). Nikakoi neustoichivosti ne naideno (zamechu, chto issledovat' vremena bolee, skazhem, pyati milliardov let neskol'ko bessmyslenno, prosto potomu, chto Solnce evolyucioniruet). Odnako eto eshe ne konec istorii. Neskol'ko let nazad Zhak Laskar pokazal, chto planetnye orbity vse-taki mogut byt' neustoichivy (ili, esli ugodno, chto obychnye metody rascheta upuskayut nekotorye vozmozhnosti razvitiya sobytii). Poskol'ku sistema imeet harakteristiki haoticheskoi sistemy, to slabye vozmusheniya mogut privodit' k bol'shim posledstviyam (effekt babochki). Laskar "rukami" vnosil slabye vozmusheniya v zemnuyu orbitu (Zemlya smeshalas' na 150 metrov v tu ili inuyu storonu), a zatem otbiral scenarii razvitiya sobytii, v kotoryh ekscentrisitet Merkuriya vozrastal. Posle shaga integrirovaniya v polmilliarda let v sistemu snova vnosilis' slabye vozmusheniya, i snova otbiralis' scenarii, gde orbita Merkuriya vse bol'she vytyagivalas'. V itoge za 6 milliardov let ekscentrisitet Merkuriya vyros do 0.5. T.e., est' malen'kaya veroyatnost' togo, chto orbity vse-taki budut sil'no drugimi spustya neskol'ko milliardov let (dlya Merkuriya Laskar poluchil ocenku veroyatnosti togo, chto ekscentrisitet vyrastet do 0.6 za 5 milliardov let, poryadka 1 procenta).

Avtory primenili laskarovskuyu tehniku i pokazali, chto orbity planet zemnoi gruppy mogut okazyvat'sya neustoichivymi na vremenah poryadka milliarda let. A vot v mire gigantov vse spokoino. Avtory ne uchityvali effekty OTO (Laskar uchityval). Oni obsuzhdayut, naskol'ko eto vazhno v dannoi zadache.


Vypusk 181. 01-17 marta 2008 goda

obzor arxiv:0803.1833 Plotnye zvezdnye populyacii: nachal'nye usloviya (Dense Stellar Populations: Initial Conditions)
Authors: Pavel Kroupa
Comments: 85 pages. To appear in The Cambridge N-body Lectures, Sverre Aarseth, Christopher Tout, Rosemary Mardling (eds), Lecture Notes in Physics Series, Springer Verlag

Zamechatel'nyi obzor po svoistvam zvezd v plotnyh skopleniyah. Vse eti dannye neobhodimy dlya zadaniya nachal'nyh uslovii pri modelirovanii dinamiki skoplenii - otsyuda i vtoraya chast' zagolovka.


Vypusk 192. 01-14 avgusta 2008

obzor arxiv:0808.0203 Uglovoi moment galaktik i ego korrelyacii (Review: galactic angular momenta and angular momentum correlations in the cosmological large-scale structure)
Authors: Bjoern Malte Schaefer
Comments: 22 pages, 7 figures, invited review for IJMPD

Galaktiki priobretayut uglovoi moment za schet prilivnyh vozdeistvii v processe formirovaniya krupnomasshtabnoi struktury. Razumeetsya, parametry vrasheniya okazyvayut skorrelirovany s drugimi parametrami galaktik i okruzhayushih ih struktur. Vse eto tak ili inache mozhet proyavlyat'sya v nablyudeniyah (v chastnosti, v dannyh po linzirovaniyu). Vsemu etomu i posvyashen dannyi obzor. Napisano otnyud' ne prosto.


Vypusk 158. 12-21 maya 2007

miniobzor arxiv:0705.2251 Haos i slozhnost' v astrofizike (Chaos and complexity in astrophysics)
Authors: Oded Regev
Comments: 2 pages,

Sobstvenno, stat'yu chitatelyam pridetsya skachivat' s saita avtora.


Vypusk 142. 01-18 oktyabrya 2006

obzor astro-ph/0610246 Otdel'nye osobennosti Galakticheskoi dinamiki (Special features of Galactic dynamics)
Authors: Christos Efthymiopoulos et al.
Comments: 96 pages, 37 figures

Bol'shoi tekst, predstavlyayushii soboi lekcii po "otdel'nym glavam Galakticheskoi dinamiki".


Vypusk 139. 01-31 avgusta 2006

astro-ph/0608087 Peredacha energii pri planetnyh proletah (The Energy Transfer Process in Planetary Flybys)
Authors: John D. Anderson, James K. Campbell, Michael Martin Nieto
Comments: 23 pages, 43 images combined into 13 figures

Ya propustil etu stat'yu, chitaya astro-ph, no, k schast'yu, ona poyavilas' v novostyah. Rabota v samom dele vazhnaya i interesnaya.

V nachale ob avtorah, chtoby ne bylo somnenii. Tochnee o pervom avtore. Po suti, eto chelovek, otkryvshii anomaliyu Pionerov. On rukovodil nebesno-mehanicheskimi raschetami v ryade proektov NASA, naprimer, Galileo. Tak chto vopros o kompetencii ne voznikaet.

Dalee. Avtory opisyvayut interesnyi nablyudatel'nyi effekt. Svyazan on s tem, chto pri gravitacionnyh manevrah, prizvannyh uvelichit' (v sluchae poletov k vneshnim planetami t.p.) ili umen'shit' (v sluchae poleta k vnutrennim planetam i drugim telam, dlya dostizheniya kotoryh nado "pritormozit'") kineticheskuyu energiyu apparata. Sam effekt horosho izvesten, on ispol'zovalsya dlya razgona Pionerov 10 i 11 i Voyadzherov, Galileo i drugih apparatov. Odnako, ne vse tak prosto. Konechno, my znachem, chto sputniki letyat kuda na do i t.p. Tem ne menee, est' ochen' malen'kii, no interesnyi effekt. Pri prolete planety apparaty poluchayut nebol'shuyu dopolnitel'nuyu energii v sravnenii s raschetnoi. Poslednee zamechanie chrezvychaino vazhno. Ne nado srazu kidat'sya delat' vyvody o tom, chto n'yutonovskaya gravitaciya dazhe blizko ne verna, i chto obnaruzhennyi effekt potryasaet vse osnovy. Vse-taki, vyvod sostoit lish' v tom, chto model', v ramkah kotoroi provodyatsya raschety, chto-to ne uchityvaet.

Sushestvenno, chto effekt est' dazhe dlya manervov apparatov okolo Zemli, prichem dazhe v sisteme koordinat, svyazannoi s Zemlei!

Avtory vidyat vozmozhnuyu svyaz' effekta s anomaliei v dvizhenii Pionerov (napomnyu, chto rech' idet o nalichii dopolnitel'nogo uskoreniya, napravlennogo primerno k Solncu). Delo v tom, chto anomaliya v dvizhenii Pionera-11 poyavilas' posle gravitacionnogo manevra okolo Saturna.

Povtoryus', chto effekt dostatochno mal, i veroyatno svyazan s nedouchetom chego-to v modeli. T.e. govorit' o "potryasanii svyashennyh korov" rano. Tem ne menee vidno, chto dazhe v horosho izvestnyh oblastyah (a nebesnaya mehanika k nim bezuslovno otnositsya) mozhno obnaruzhivat' ochen' interesnye effekty!


Vypusk 135. 22 aprelya - 31 maya 2006

astro-ph/0605026 Forma galo Mlechnogo Puti (The Shape of the Milky Way Halo)
Authors: M. Fellhauer et al.
Comments: ApJ (Letters), submitted

Dobavlyu, chto dannye o forme galo vazhny, kak eto ne stranno, i dlya fiziki elementarnyh chastic. Delo v tom, chto ryad avtorov pytaetsya ob'yasnit' izbytok gamma-luchei, nablyudavshiisya priborom EGRET, kak izluchenie temnoi materii v galo nashei galaktiki. Izluchenie voznikaet blagodarya raspadu chastic temnoi materii. Novye dannye o forme galo dolzhny pomoch' utochnit' modeli gamma-izlucheniya. T.o., vozmozhno, mozhno budet poluchit' dannye o supersimmetrii ne iz uskoritel'nyh eksperimentov, a iz astrofizicheskih dannyh.


Vypusk 130. 01-13 marta 2006

physics/0603066 Dinamicheskoe trenie v zvezdnyh sistemah: vvedenie (Dynamical Friction in Stellar Systems: an introduction)
Authors: Hector Aceves, Maria Colosimo
Comments: 10 pages, 5 figures. Submitted to Am. J. Phys

Horoshee opisanie dinamicheskogo treniya v zvezdnyh sistemah. Neponyatno, pochemu avtory polozhili stat'yu v etu chast' Arhiva, a ne v astro-ph.

Napomnyu, chto yavlenie dinamicheskogo treniya harakternoi dlya sistem mnogih tel. Skazhem zvezda, dvigayas' sredi drugih zvezd, budet ispytyvat' silu, napravlennuyu protiv dvizheniya. Proishozhdenie sily chisto gravitacionnoe. Svyazano ono s tem, chto sama zvezda sozdaet svoei gravitaciei szadi sebya sgushenie. Pohozhee yavlenie budet voznikat' pri dvizhenii lyuboi tyazheloi chasticy v szhimaemoi srede. Vpervye dannyi fenomen byl rassmotren Chandrasekarom. Polagayu, chto stat'ya budet interesna mnogim. Ee mozhno i polezno razbirat' v kachestve primera na seminarah po mehanike ili dazhe s razumnymi devyatiklassnikami.

Vypusk 102. 21-31 marta 2005

stat'ya v enciklopedii astro-ph/0503600 Klassicheskaya zadacha mnogih tel v gravitacii (The Classical Gravitational N-Body Problem)
Authors: Douglas C. Heggie
Comments: 29 pages, 4 figures, to appear in Encyclopaedia of Mathematical Physics, Elsevier, 2006

Obshirnaya enciklopedicheskaya stat'ya, posvyashennaya metodu mnogih tel v gravitacii.

Vse znayut, chto uzhe zadacha treh tel v obshem vide ne imeet polnogo analiticheskogo resheniya. Odnako v astronomii splosh' i ryadom vstrechayutsya situacii vzaimodeistviya mnozhestva ob'ektov. Dlya resheniya takih zadach byli razrabotany kak chislennye, tak i priblizhennye analiticheskie metody. Obo vsem etom - v stat'e.


Vypusk 95. 22-31 dekabrya 2004

obzor astro-ph/0412311 Vekovaya ustoichivost' i neustoichivosti zvezdnyh sistem, okruzhayushih massivnye ob'ekty (Secular stability and instability in stellar systems surrounding massive objects)
Authors: Scott Tremaine
Comments: 30 pages

Avtor issledoval ustoichivost' malomassivnyh zvezdnyh skoplenii vokrug tyazhelyh central'nyh ob'ektov. Primerom takih sistem yavlyaetsya zvezdnoe skoplenie vokrug central'noi chernoi dyry nashei Galaktiki i kometnoe oblako Oorta vokrug Solnca.

Pri otsutstvii samogravitacii (t.e. kogda dvizhenie zvezd opredelyaetsya tol'ko central'nym ob'ektom) ustoichivost' takih sistem zavisit ot funkcii ih raspredeleniya F po uglovomu momentu J: esli pri fiksirovannoi energii

dF/dJ < 0
to vse sfericheskie sistemy okazyvayutsya ustoichivymi, v protivnom sluchae, pri
dF/dJ > 0
sistema nestabil'na. Pri otsutstvii vrasheniya (J=0) sistema neustoichiva vsegda.


astro-ph/0412622 Stolknoveniya zvezd i obrazovanie chernyh dyr v plotnyh zvezdnyh skopleniyah (Stellar Collisions and Black Hole Formation in Dense Star Clusters)
Authors: Stephen McMillan, Simon Portegies Zwart
Comments: 6 pages, 1 figure

Tesnye prolety i lobovye stolknoveniya zvezd v plotnyh skopleniyah (sharovyh i skopleniyah vblizi centrov galaktik) privodyat k obrazovaniyu ochen' massivnyh zvezd, kotorye, posle bystroi termoyadernoi evolyucii, porozhdayut chernye dyry. Ob'ekty, obrazovavshiesya v rezul'tate sliyanii, obychno imeyut vysokuyu prostranstvennuyu skorost' ("ubegayushie zvezdy"). Vazhnye detali dannyh processov byli provereny metodom N-tel.

V nebol'shih skopleniyah chislo slivayushihsya ob'ektov ogranichivaetsya prosto kolichestvom massivnyh zvezd, v bol'shih skopleniyah - chislom massivnyh zvezd v ih yadrah.


astro-ph/0412663 Evolyuciya plotnyh zvezdnyh skoplenii (Evolution of dense stellar clusters)
Authors: G.S. Bisnovatyi-Kogan
Comments: 8 pages, 1 figure; Pisma Astron. Zh., 4, 130-133 (March 1978)

Mnogie klassicheskie stat'i, osobenno opublikovannye ne v troike vedushih zhurnalov, dostatochno maloizvestny i malocitiruemy prosto potomu, chto oni ne dostupny v Seti. Priyatno, chto nekotorye iz klassikov vykladyvayut svoi starye raboty v Set', da eshe i pryamo v Arhiv.

Kak yasno iz nazvaniya, v stat'e rassmotrena evolyuciya plotnyh zvezdnyh skoplenii. Za schet vzaimodeistviya zvezd drug s drugom chast' iz nih vybrasyvaetsya iz skopleniya. Ostavshiesya obrazuyut vse bolee i bolee plotnoe skoplenie. V konce koncov skoplenie kollapsiruet.


Vypusk 70. 16-22 fevralya 2004

obzor astro-ph/0402335 Regulyarnye dvizheniya v sistemah ekzoplanet (Regular Motions in Extra-Solar Planetary Systems)
Authors: S. Ferraz-Mello et al.
Comments: 25 pages, 11 figures, to be published in "Chaotic Worlds: From Order to Disorder in Gravitational N-Body Systems" (B.A.Steves, ed.), Kluwer Acad. Publ.

Eto obzor po dinamike planetnyh sistem v primenenii k ekzoplanetam. Stat'ya dostatochno tehnicheskaya, no vmeste s tem dostupnaya kazhdomu, kto pomnit standartnyi universitetskii (institutskii) kurs po teormehu.


Vypusk 66. 19-26 yanvarya 2004

astro-ph/0401451 Modelirovanie vybrosa zvezd iz tumannosti Oriona (N-body simulations of stars escaping from the Orion nebula)
Authors: A.Gualandris et al.
Comments: 14 pages, 13 figures, 5 tables.

Ot tumannosti Oriona v pochti protivopolozhnyh napravleniyah udalyayutsya dve odinochnye ubegayushie zvezdy AE Aurigae i μ Columbae. Krome togo ot tumannosti so skorost'yu bol'shei 100 km/s letit dvoinaya sistema ι Ori s ekscentrisitetom orbity e=0.8. Vse eti zvezdy vyleteli iz tumannosti primerno 2.5 mln. let nazad. Avtory raboty pytayutsya smodelirovat' dannoe sobytie.


Shema odnogo iz variantov razleta


Vypusk 65. 12-19 yanvarya 2004

astro-ph/0401171 (Ne)Stabil'nost' planentyh sistem (The (In)Stability of Planetary Systems)
Authors: Rory Barnes, Thomas Quinn
Comments: 37 pages, 49 figures, 13 tables, submitted to ApJ

Ochen' ob'emnaya stat'ya, posvyashennaya chislennomu issledovaniyu ustoichivosti sushestvuyushih planetnyh sistem. Planetnymi sistemami obladayut zvezdy, u kotoryh otkryto uzhe hotya by dve planety. Takih sistem izvestno okolo desyati, avtory proveli modelirovaniya dlya ipsilon And, HD83443, GJ876, HD82943, 47UMa, HD168443 i, konechno, dlya Solnechnoi sistemy.

Modelirovanie zaklyuchalos' v sleduyushem: dlya kazhdoi sistemy 1000 raz provodilos' chislennoe integrirovanie ee dvizheniya na intervale primerno v 1 million let. Parametry sistem bralis' iz nablyudenii i slegka var'irovalis'.

Vyvody avtorov takovy: rezonansnye sistemy (HD82943 and GJ876) imeyut ochen' uzkuyu oblast' ustoichivosti; vzaimodeistvuyushie (no bez rezonansa) sistemy (ipsilon And, 47UMa i Solnechnaya sistema) - gorazdo bolee shirokuyu oblast' stabil'nosti; a shirokie sistemy (takih mnogo, avtory proveli modelirovanie tol'ko dlya HD83443 i HD168443) ustoichivy.


(Arhiv Dinamika:
v.2, 2003, v.1, 2002-2003)

Publikacii s klyuchevymi slovami: astrofizika - obzory - astro-ph
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