Novosti nauki |
The R.A.P. Project |
08.08.02. astro-ph za 05 avgusta - 08 avgusta 2002 goda: izbrannye stat'i |
Avtory predlagayut provetsi obzor neba s pomosh'yu nebol'shogo teleskopa s cel'yu poiska ekzoplanet, registriruya ih prohozhdeniya po diskam "materinskih" zvezd. Obsuzhdaetsya sootvetstvuyushaya teoriya i dayutsya ocenki vozmozhnogo chisla planet, kotorye mozhno obnaruzhit' takim sposobom.
Authors: F. Courbin et al. Comments: Review on quasar lensing. Part of a LNP Topical Volume "Dark matter and gravitational lensing" (eds. Courbin, Minniti) to be published by Springer-Verlag, 2002. Paper with full resolution figures at: ftp://ftp.astro.ulg.ac.be/pub/users/courbin/ Obsuzhdayutsya razlichnye aspekty linzirovaniya kvazarov.
Authors: D. R. Gies, W. Huang, M. V. McSwain Comments:Submitted to ApJL, 16 pages, 3 figures Vpervye po spektral'nym liniyam opticheskogo kompan'ona opredelena massa relyativistskogo ob'ekta v SS433. Ona okazalas' ravnoi 11+/-5 mass Solnca, t.e. komponent yavlyaetsya chernoi dyroi!
Authors: D. Wittman Comments: Part of a LNP Topical Volume "Dark matter and gravitational lensing" (eds. Courbin, Minniti) to be published by Springer-Verlag, 2002. I rely on an earlier chapter in this volume to explain the basic lensing equations (see astro-ph/0208043). 43 pages; full-resolution version at http://dls.bell-labs.com/Pubs/WeakLensing.ps.gz Obzor po slabomu linzirovaniyu dlya studentov.
Authors: G. Brunetti Comments: 15 pages, 5 figures, Invited Review Talk, to appear in the Proc. of "Matter and Energy in Clusters of Galaxies", April 23-27 2002, Taiwan, S.Bowyer and C.-Y. Hwang, Eds Obsuzhdaetsya otkuda berut'sya relyativistskie elektrony v mezhgalakticheskoi srede, i chto s etimi elektronami proishodit. Obsuzhdayutsya parametry magnitnyh polei v skopleniyah galaktik.
Authors: S.C. Beck et al. Comments: Accepted for publication in The Astronomical Journal (~November 2002), 26 pages and 4 JPEG figures II Zw 40 eto karlikovaya galaktika na rasstoyanii primerno 10 Mpk ot nas. V etoi galaktike proishodit burnoe zvezdoobrazovanie, kotoroe obychno soprovozhdaetsya mnozhestvom interesnyh processov i poyavleniem razlichnyh lyubopytnyh struktur. Na osnove dannyh, poluchennyh na VLA i teleskope im. Keka v radio i IK diapazonah, avtory stat'i rasskazyvayut o svoih issledovaniyah t.n. sverhtumannosti. Eto struktura, sstoyashaya iz mnozhestva oblastei ionizovannogo vodoroda. Svoim obrazovaniem ona obyazana zvezdnomu sverhskopleniyu, v kotoroe vhodit po krainei mere 14 tysyach zvezd klassa O. Sverhtumannost' obespechivaet b\'ol'shuyu chast' IK potoka ot galaktiki.
Authors: Shiv S. Kumar Comments: 9 pages, invited review paper presented at IAU211 Symposium at Waikoloa, Hawaii (May 2002), to appear in the proceedings Daetsya istoricheskii obzor teoreticheskih i nablyudatel'nyh issledovanii malomassivnyh ob'ektov, massy kotoryh men'she predela zagoraniya vodoroda (0.08 mass Solnca dlya chisto vodorodnogo sostava). Obsuzhdaetsya teoriya fragmentacii molekulyarnyh oblakov. Krome staryh (60-e gg.) rassmatrivayutsya i novye rezul'taty, v chastnosti rassmatrivayutsya razlichiya v obrazovanii zvezd i planet.
Authors: D. Clowe, P. Schneider Comments: accepted to A&A, 14 pages, 13 figures, version with higher quality images can be found at http://www.uni-bonn.de/~clowe Na primere A1835 i A2204 mozhno posmotret', kak opredelyayut raspredelenie massy v skopleniyah galaktik po linzirovaniyu. Opredelennye massy nahodyatsya v sootvetstvii s ocenkami, sdelannymi po rentgenovskim nablyudeniyam, a takzhe po issledovaniyu dinamiki skoplenii.
Authors: Z. Ivezic et al. Comments: 6 pages, 1 color figure, to be presented at "Astronomical Telescopes & Instrumentation", SPIE 2002 Sloanovskii Cifrovoi Obzor Neba - proekt, dayushii kolossal'noe kolichestvo informacii, kotoruyu mozhno ispol'zovat' ne tol'ko v kosmologii. V chastnosti, est' Sloanovskii katalog dvizhushihsya ob'ektov. V osnovnom eti ob'ekty - asteroidy (58117 shtuk! iz nih okolo 10000 - izvestnye). Poskol'ku nablyudeniya provodyatsya v neskol'kih cvetah (dlya kosmologii eto vazhno, tak kak daet vozmozhnost' ocenit' krasnoe smeshenie vnegalakticheskih ob'ektov), to mozhno issledovat' cveta asteroidov. Na osnove dannyh o cvetah avtory stat'i rassmatrivayut raspredelenie asteroidov po semeistvam (ih naschityvaetsya 4). Delaetsya vyvod, chto razlichiya himicheskogo sostava vnutri semeistv namnogo men'she razlichii mezhdu raznymi semeistvami. Eto mozhet govorit' o sovmestnom proishozhdenii asteroidov, prinadlezhashih odnomu semeistvu.
Authors: J. W. Moffat, G. T. Gillies Comments: 8 pages. Latex file. No figures Predlagaetsya povtorit' eksperiment Etvesha po proverke slabogo principa ekvivalentnosti, no na etot raz v kosmose. Obsuzhdaetsya svyaz' predpolagaemyh rezul'tatov s kosmologicheskim chlenom.
Authors: Joshua A. Frieman et al. Comments: 11 pages, 11 figures, submitted to Phys. Rev. D
Authors: Joseph J. Mohr et al. Comments: Latex 5 pages, 4 figures, contribution to Dark Matter 2002 conference proceeding Kak mozhno "izuchat' i probovat'" temnuyu energiyu? Sushestvuet neskol'ko osnovnyh kosmologicheskih testov: habblovskii potok, pervichnyi nukleosintez, reliktovoe izluchenie, krupnomasshtabnaya struktura. Vse oni pozvolyayut nakladyvat' ogranicheniya na kosmologicheskie modeli (sm., naprimer, astro-ph/0208133, gde avtory pytayutsya ispol'zovat' nukleosintez dlya ogranichenii na brannye modeli; a takzhe astro-ph/0208114, gde obsuzhdaetsya, kak po nablyudeniyam reliktovogo izlucheniya, v prilozhenii k budushei missii PLANCK, mozhno opredelyat' kosmologicheskie parametry). V svoih stat'yah avtory astro-ph/0208100 i astro-ph/0208102 ispol'zuyut sootvetstvenno habblovskii potok (dannye po sverhnovyh pozvolyayut nezavisimo opredelyat' rasstoyaniya do galaktik, skorosti kotoryh izvestny po krasnomu smesheniyu) i reliktovoe izluchenie i nablyudeniya skoplenii galaktik dlya polucheniya dannyh o svoistvah temnoi energii. Nikakih novyh vyvodov avtorami ne sdelano, odnako mozhno naiti podrobnuyu diskussiyu o sostoyanii del v nastoyashii moment i o vozmozhnom progresse v samom blizhaishem budushem.
Authors: Robert H. Brandenberger Comments: 8 pages, 8 figures commissioned article for the AAPPS Bulletin, appeared in 2001 Po-prezhnemu polagayu, chto luchshie obzory po inflyacii pishet Linde. Odnako, esli interesno pochitat' "nezainteresovannyh lic" (Linde vse-taki sozdatel' sovremennoi modeli inflyacii), to vot neplohoi obzor. V obzore obsuzhdayutsya osnovy modeli, nereshennye problemy. Osoboe vnimanie udelyaetsya formirovaniyu "zarodyshei", iz kotoryh vposledstvii vyrastaet krupno-masshtabnaya struktura.
Authors: R. Battiston Comments: 18 pages, 12 figures, Invited Talk at the ESO-CERN-ESA Symposium on Astronomy, Cosmology and Fundamental Physics, March 4-7 2002, Garching, Germany Obsuzhdayutsya planiruemye kosmicheskie proekty v oblasti kosmomikrofiziki, a takzhe nereshennye problemy, radi kotoryh eti sputniki i sozdayutsya. Osoboe vnimanie udeleno kosmicheskim lucham. Sootvetstvenno obsuzhdayutsya eksperimenty AMS, PAMELA, Polar BESS. Eti eksperimenty svyazany s Mezhdunarodnoi kosmicheskoi stanciei, chto interesno v svyazi s voprosom "zachem nam nuzhna MKS?", kotoryi inogda vsplyvaet na forumah...
Authors: F. Combes Comments: 27 pages, 10 figures, review article in 7th cosmology colloquium, High Energy Astrophysics, for and from Space, Paris, 11-15 Juin 2002 N. Sanchez and H. de Vega, Editors Obsuzhdayutsya sverhmassivnye chernye dyry: kak ih sdelat', chem ih "kormit'" i chto pri etom proishodit.
Authors: E. Hawkins, S.J. Maddox, M.R. Merrifield Comments: 4 pages, 5 figures, MNRAS accepted Avtory issledovali raspredelenie kvazarov v kataloge 2dF na predmet nalichiya periodichnosti ih raspredeleniya po krasnomu smesheniyu (ranee podobnaya periodichnost' vrode by byla obnaruzhena). Rezul'tat poiska otricatel'nyi. Stat'ya korotkaya, i napisana ponyatno i interesno. Sovetuyu prochest'.
Authors: Shizuka Akiyama, J. Craig Wheeler et al. Comments: 42 pages, including 15 figures. Accepted for publication in ApJ Poka nikto ne znaet kak vzryvayutsya sverhnovye. Est' tri osnovnyh mehanizma (zdes' privoditsya otryvok iz nashego obzora): Pervyi mehanizm ob'edinyaet klassicheskuyu model' "otskoka" ("bounce") padayushih vneshnih sloev yadra predsverhnovoi ot sformirovavshegosya i stavshego zhestkim sverhplotnogo ostatka sverhnovoi (goryachei proto-NZ) s neitrinnymi mehanizmami, v kotoryh obrazovavshayasya v rezul'tate otskoka udarnaya volna v dal'neishem podpityvaetsya neitrinnym izlucheniem goryachego yadra. Eto samaya pervaya i dolgoe vremya schitavshayasya osnovnoi model' vzryva sverhnovoi. Hotya ranee v ramkah etoi modeli neskol'ko raz udavalos' ob'yasnit' vspyshku sverhnovoi, posleduyushie bolee tochnye issledovaniya otvergali eti naidennye vozmozhnosti. Na segodnya dannyi mehanizm ne ob'yasnyaet sbros obolochki sverhnovoi ni v sfericheski simmetrichnom, ni v osesimmetrichnom (s vrasheniem) sluchayah. Est' nadezhda, chto situaciyu mogla by ispravit' krupnomasshtabnaya neitrinnaya konvekciya. V nastoyashee vremya v dannom napravlenii vedutsya intensivnye issledovaniya. Drugoi mehanizm (Imshennik 1992) svyazan s deleniem bystrovrashayushegosya kollapsiruyushego yadra zvezdy na 2 chasti, po krainei mere odna iz kotoryh dolzhna byt' neitronnoi zvezdoi. Zatem chasti dvoinogo yadra sblizhayutsya iz-za gravitacionnogo izlucheniya, poka men'shaya po masse (i bol'shaya po razmeru) komponenta ne zapolnit svoyu polost' Rosha. Sblizhenie dvoinogo yadra mozhet dlit'sya ot neskol'kih minut do neskol'kih chasov. Posle etogo nachinaetsya peretekanie veshestva do teh por, poka massa men'shei komponenty ne dostignet nizhnego predela mass NZ (okolo 0.09M), pri kotorom proishodit vzryvnaya deneitronizaciya malomassivnoi neitronnoi zvezdy. Takoe dopolnitel'noe vydelenie energii, proishodyashee dostatochno daleko ot centra kollapsiruyushei zvezdy, mozhet effektivno sbrosit' ee obolochku. Etot mehanizm mozhet deistvovat' tol'ko u naibolee bystro vrashayushihsya predsverhnovyh. Problema dannogo scenariya zaklyuchena v tom, chto poka eshe nikomu ne udalos' vosproizvesti delenie yadra predsverhnovoi pri kollapse. Poslednii iz rassmatrivaemyh nami mehanizmov vzryvov sverhnovyh - magnitorotacionnyi - byl predlozhen G.S.Bisnovatym-Koganom v 1970 g. Ideya etogo mehanizma ochen' prosta - sbros obolochki proizvoditsya magnitnym polem bystro vrashayusheisya NZ. Pri etom obolochka uskoryaetsya za schet tormozheniya vrasheniya neitronnoi zvezdy. Poskol'ku na samom dele eta prostaya ideya ob'edinyaet v sebe generaciyu i usilenie magnitnyh polei i slozhnuyu trehmernuyu gidrodinamiku s sil'nym vliyaniem perenosa izlucheniya, to realistichnye raschety dannogo scenariya kraine zatrudneny. Rezul'taty dvumernyh raschetov pokazyvayut, chto magnitorotacionnyi mehanizm mozhet peredat' neskol'ko procentov vrashatel'noi energii kompaktnogo ostatka v kineticheskuyu energiyu obolochki. Kak pokazyvayut upomyanutye raschety, magnitorotacionnyi vzryv (stadiya na kotoroi proishodit sushestvennoe uskorenie i sbros obolochki) dlitsya 0.01-0.1 s. Odnako emu predshestvuet faza "nakrutki", na kotoroi toroidal'noe magnitnoe pole lineino usilivaetsya do kriticheskoi velichiny pri kotoroi proishodit sbros obolochki. Dlitel'nost' etoi stadii zavisit ot velichiny nachal'nogo magnitnogo polya NZ i ot skorosti ee vrasheniya i mozhet menyat'sya ot dolei sekundy do minut (i dazhe chasov). Dlya dannogo mehanizma trebuetsya dostatochno bystroe vrashenie NZ (period poryadka neskol'kih millisekund), odnako ne stol' bystroe, kak v mehanizme s deleniem yadra. V rassmatrivamoi stat'e Akiyamy i dr. issleduetsya magnitovrashatel'naya neustoichivost', privodyashaya k rostu magnitnogo polya pri kollapse. Bipolyarnye potoki, voznikayushie blagodarya neustoichivosti, mogut sushestvenno vliyat' na vzryv, ili dazhe yavlyat'sya ego osnovnym "dvigatelem".
Authors: Jason X. Prochaska Comments: pages, 4 figures. To appear in "Hubble's Science Legacy: Future Optical-Ultraviolet Astronomy from Space", APS Conf. Series V samom nedalekom budushem my budem ochen' mnogo znat' o zvezdnoi sostavlyayushei galaktik na z<2 (sm. takzhe sleduyushuyu stat'yu). Odnako, po mneniyu avtora, informacii o gazovoi sostavlyayushei galaktik budet nedostatochno, i pomoch' zdes' mozhet tol'ko ul'trafioletovyi Kosmicheskii teleskop novogo pokoleniya (Next Generation Space Telescope). Na bol'shih krasnyh smesheniyah diagnostika gaza provoditsya po nablyudeniyam t.n. "laiman-al'fa lesa". Dlya z<2 etot metod ploho rabotaet.
Authors: Sidney van den Bergh Comments: 8 pages. No figures Korotkii ponyatnyi obzor po evolyucii galaktik razlichnyh tipov (k sozhaleniyu, bez kartinok). Progress v dannoi oblasti svyazan v pervuyu ochered' s glubokimi habblovskimi nablyudeniyami, pozvolyayushimi poluchat' kachestvennye izobrazheniya dalekih galaktik. Na z<1 osnovnoe zvezdoobrazovanie idet v diskah, a na z>2 - v haoticheskih strukturah, "blobah" i t.p., chto otchasti svyazano so stolknoveniyami (sliyaniyami) galaktik na bol'shih krasnyh smesheniyah. Galaktiki rannih (ellipticheskie i Sa-Sab) i pozdnih (Sbc-Sc) tipov evolyucioniruyut po-raznomu. Na bol'shih krasnyh smesheniyah bol'she ob'ektov, kotorye ne popadayut na Habblovskuyu diagrammu. Krome togo, tam men'she galaktik s barami (a vokrug nas ih kolichestvo nezavisit ot galakticheskogo okruzheniya).
Authors: Ramesh Narayan, James E. Pringle Comments: 4 pages; not submitted to any journal Dlya lyubitelei polemiki. Stat'ya yavlyaetsya korotkim kommentariem na rabotu astro-ph/0207561, o kotoroi ya tozhe pisal. Sut' kommentariya ochen' prosta: vyvody v astro-ph/0207561 neverny.
Arhiv statei, voshedshih v predydushie vypuski.
Razdely arhiva (s iyulya 2002 g.): Poleznye astronomicheskie ssylki. Obzornye stat'i v astro-ph s 2001 g. |
|
Publikacii s klyuchevymi slovami:
elektronnye preprinty - obzory - astro-ph
Publikacii so slovami: elektronnye preprinty - obzory - astro-ph | |
Sm. takzhe:
Vse publikacii na tu zhe temu >> |