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4. Analiz
4.1. Obshie ocenki
Analiz vliyaniya oshibok opredeleniya konstant himicheskih reakcii na rezul'taty modelirovaniya proizvodilsya sleduyushim obrazom.
Dlya kazhdogo soedineniya byli opredeleny znacheniya minimal'nogo i maksimal'nogo logarifmov ravnovesnyh obilii po otnosheniyu k vodorodu. Posle etogo poluchennye intervaly byli razbity na 100 ravnyh chastei i poschitano kolichestvo modelei, dlya kotoryh znachenie sootvetstvuyushego obiliya popalo v kazhdyi iz intervalov. Dlya vseh soedinenii byli postroeny sootvetstvuyushie gistogrammy. Na risunkah 1, 2, 3, 4 i 5 predstavleny gistogrammy dlya HCN, HC3N i HC5N, a takzhe dlya otnoshenii HCN/ HC3N i HC3N/ HC5N. Eti sootnosheniya budut rassmotreny podrobno dalee.
Vse 384 himicheskih soedineniya byli razbity na 6 grupp po ustoichivosti znacheniya ih obilii k var'irovaniyu konstant skorostei. Osnovoi deleniya stala shirina gistogrammy na vysote, sootvetstvuyushei polovine znacheniya maksimuma gistogrammy. Raspredelenie soedinenii po gruppam predstavleno v tablice 3.
V 1-yu gruppu ustoichivosti popalo 11 himicheskih elementov i soedinenii. Preobladayut himicheski neaktivnye elementy i soedineniya. Odnako est' i isklyucheniya. Samoe yarkoe himicheski aktivnyi ion H3O+.
Absolyutnoe bol'shinstvo iz 384 soedinenii popali vo 2, 3 i 4 gruppy (36, 119 i 153 soedineniya sootvetstvenno). Prichem, bol'shaya chast' obil'nyh v mezhzvezdnoi srede soedinenii okazalis' vo 2 i 3 gruppah (CO, CS, H2CO, NH3, CH3OH, H2O, CH4 i drugie).
Odnako nekotorye nablyudaemye soedineniya, v chastnosti, cianopoliiny, okazalis' v 4 gruppe ustoichivosti.
V celom, horosho proslezhivaetsya tendenciya popadaniya bolee slozhnyh i tyazhelyh soedinenii v gruppu ustoichivosti s bol'shim nomerom. Fizicheskim ob'yasneniem etogo, po-vidimomu, yavlyaetsya to, chto k obrazovaniyu bolee slozhnyh (sostoyashih iz bol'shogo chisla atomov) soedinenii privodyat bolee dlinnye cepochki himicheskih reakcii, nezheli k obrazovaniyu prostyh soedinenii. Oshibki opredeleniya konstant himicheskih reakcii v dlinnyh cepochkah, peremnozhayas' mezhdu soboi, sushestvenno snizhayut tochnost', s kotoroi poluchaetsya obilie konechnogo produkta rassmatrivaemoi slozhnoi molekuly. V 5, 6 i 7 gruppah nahodyatsya, preimushestvenno nenablyudaemye v nastoyashee vremya slozhnye molekuly s dlinnymi uglerodnymi cepochkami, obrazuyushiesya v konce slozhnoi cepochki himicheskih reakcii.
V mezhzvezdnoi srede nablyudaetsya bol'shoe kolichestvo otnositel'no legkie molekuly. Tochnost' opredelenii ih obilii iz nablyudatel'nyh dannyh sostavlyaet, kak pravilo, 1-1,5 poryadka. Takim obrazom, mozhno sdelat' vyvod, chto vliyanie oshibok opredeleniya konstant himicheskih reakcii nekritichno dlya modelirovaniya obilii legkih molekul, imeyushih dostatochno prostuyu strukturu.
V to zhe vremya, vliyanie oshibok opredeleniya konstant himicheskih reakcii sushestvenno bol'she dlya molekul s uglerodnymi cepochkami i bystro narastaet s uvelicheniem dliny cepochki. Dlya molekul s 4-atomnoi uglerodnoi cepochkoi oshibka sostavlyaet poryadka 2 poryadkov, no dlya 8-9-atomnyh prevyshaet 3.5 poryadka, chto sushestvenno dlya lyubyh modelei.
4.2. Vliyanie oshibok konstant reakcii na opredelenie vozrasta oblakov.
Kak bylo skazano vo vvedenii, oshibki opredeleniya obilii soedinenii i ih otnoshenii mogut sushestvenno otrazhat'sya na nashih znaniyah o fizicheskih svoistvah rassmatrivaemyh ob'ektov. Horoshei illyustraciei etogo utverzhdeniya yavlyaetsya zavisimost' vozrasta molekulyarnyh oblakov, poluchaemaya iz otnoshenii obilii cianopoliinov, ot oshibki modelirovaniya etih otnoshenii.
Na risunkah 1, 2, 3 i 4 pokazano raspredelenie obilii HCN, HC3N i HC5N molekul, ispol'zuyushihsya dlya ocenki vozrasta, - v nashih modelyah.
Tablica 3. Raspredelenie
himicheskih elementov i soedinenii
po gruppam tochnosti.
1 Δ Log Ab < 0.25 |
2 Δ Log Ab 0.25 0.5 |
3 Δ Log Ab 0.5 1.0 |
4 Δ Log Ab 1.0 2.0 |
5 Δ Log Ab 2.0 3.0 |
6 Δ Log Ab 3.0 4.0 |
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H2 He P Cl Na+ SO Mg+ O2 N2 Fe+ H3O+ |
H N O Na Mg Fe H+ He+ NH3+ N2+ NH3 CS PO HCl H2+ HCO+ NH2+ CO+ N2H+ HPO+ H2O HeH+ NH+ H2O+ HOC+ HCS+ SO+ H3+ OH+ NH4+ O2+ O+ Si+ SiO+ SiOH+ PO+ |
C S Si NH OH H2CO H2S NO2 OCN SiN C3O SO2 C- S- SiCH3 CH3OH N+ O- SiH+ NO+ SiH3+ PH2+ SiH5+ HCl+ PN+ NO2+ CH4N+ CH3CO+ HPN+ HNS+ PC2H3+ CH3 HNO C2H2 CP CH2+ CH5+ SiH2+ H3CO+ CH3OH2+ HCP+ CS+ HSO2+ NCO+ PCH3+ HSO+ HOCS+ CO2 OCS PH HPO HCP CH4+ HCNH+ H2CO+ S+ PH3+ H2S+ H2Cl+ HNSi+ |
CO2+ SO2+ PCH2+ PNH2+ H3SiO+ H2PO+ H3C3O+ HSiO2+ CH NH2 HCO HS N2O C2H CH2PH ClO SiCH2 H2SiO CHOOH C+ CH3+ C2H3+ P+ HS+ Cl+ SiCH3+ SiNH2+ H2NO+ PCH4+ PNH3+ CCl+ CHOOH2+ H2CCl+ OCS+ CH2 CH4 CO NO O2H NS CN SiH PN CCl H- SiH4 HNSi SiO2 CH+ OH- C2H4+ HNO+ PH+ O2H+ H3S+ SiCH2+ SiCH4+ NS+ PC2H2+ |
C2H3 SiH2 C3H HCS PH2 C5N CH3OCH3 C2S SiC3H C4S CN- C3H2+ HCSi+ CP+ H5C2O+ C3N+ SiC2H+ SiC2H3+ S2H+ SiC3H2+ CNC+ C2HO+ H2SiO+ C2H7O+ C2N2+ C3H2O+ HSiS+ SiC3+ HC3S+ SiC4H+ HC4S+ HCN H2O2 SiH3 C3H2 C3 C4H SiNC SiC3 SiC4 HNC CH3CHO HC3N C2H6CO CH3CN C2H2+ SiH4+ C3+ C3H3+ C3H5+ C2H5O+ |
C4H2+ C4H5+ PC2H+ C5H4+ HC2S+ CH2NH2+ CCNH+ H3CHO+ 2H5OH+ H3CS+ H2C3N+ CCP+ H2S2+ SiC4+ C4P+ H2CN C3H3 C5H CCN C3N CCP C3P C4P CH2NH CH2CN H2CS SiC2H SiS H2S2 CH2CO C2+ HCN+ H2C3H+ CH3CN+ HC3N+ SiNC+ C2S+ SiC3H+ C2H7+ C2O+ CH2CO+ C2H6O+ C3O+ C3H6OH+ H3S2+ PC4H+ C2 S2 C2H4 H2C3 C4H2 |
SiC CCO HCCP C2H6 H3C3N HCOOCH3 C3S C2H+ H2NC+ C2H5+ C3H+ SiC+ SiN+ HCO2+ C4+ C4H3+ SiC2H2+ C5H2+ CH2CN+ H4C2N+ HC3O+ PC2H4+ H5C2O2+ PC3H+ C3H4 C2H5 HCSi SiC2 C5 C2H5OH SiC2H2 HS2 CN+ C2H6+ CCN+ C3H4+ C4H+ SiC2+ SiNCH+ SiS+ CH3OH+ HC2O+ HNCO+ H2CS+ C2H6OH+ ClO+ H4C3N+ OOCH4+ S2+ C3S+ C4S+ |
C5H4 C4 C5+ C5H3+ C6H3+ C7H2+ C5N+ C6H2 H3C4N H3C6N C5H+ HC5N+ C7H3+ C8H+ C2H6CO+ C7H2 C7N HC7N C4N+ C6+ C6H5+ C7H4+ C8H2+ H2C5N+ C7H4 C6 C7 H2C4N+ H3C4N+ C6H+ C7+ C7H5+ HC7N+ C6H4+ PC4H2+ H2C7N+ C5H2 C6H C7H HC5N HC4N+ C5H5+ H4C4N+ C6H2+ C7H+ H4C6N+ H3C5N+ |
C8 C9N HC9N C8+ C9H+ C9H5+ C8H SiO C9H2+ C7N+ C8H4+ C10+ C9H3+ C9N+ C8H5+ H2C9N+ C9 C9H2 C8H3+ C9H4+ H3C9N+ C8H2 C9H H3C8N C9+ H4C8N+ HC9N+ H3C7N+ |
Chernoi strelkoi na risunkah ukazano obilie himicheskogo soedineniya, poluchaemoe pri ispol'zovanii neizmenennoi bazy UMIST 95.
Vidno, chto velichina razbrosa obilii cianopoliinov vozrastaet s uvelicheniem kolichestva atomov v molekule. Dlya HCN velichina razbrosa na polovine vysoty gistogrammy ravna 1.00 poryadka, dlya HC3N 1.50 poryadka, a dlya HC5N uzhe 2.05 poryadka. Ochevidno, eto svyazano s uvelicheniem dliny cepochki himicheskih reakcii, privodyashih k obrazovaniyu cianopoliinov s uvelicheniem chisla atomov v nih.
V nastoyashee vremya ryad specialistov rassmatrivaet vozmozhnost' ispol'zovaniya otnosheniya obilii nekotoryh molekul dlya ocenki vozrasta molekulyarnyh oblakov. V chastnosti, dlya etih celei predlagaetsya ispol'zovat' otnoshenie obilii cianopoliinov (naprimer, HCN/HC3N, HC3N/HC5N) [6]. V svyazi s etim interes predstavlyaet razbros znachenii etih otnoshenii v rasschitannyh modelyah, predstavlennyi na risunkah 4 i 5.
V oboih sluchayah velichina razbrosa otnosheniya v poschitannyh modelyah sostavlyaet priblizitel'no 1 poryadok, chto sushestvenno huzhe tochnosti nablyudatel'nogo opredeleniya otnoshenii HCN/HC3N i HC3N/HC5N. Takaya nizkaya tochnost' model'nogo rascheta etih otnoshenii privedet k pogreshnosti togo zhe poryadka pri opredelenii vozrasta ob'ektov pri ih pomoshi.
Privedennye vyshe primer, na nash vzglyad, horosho illyustriruet sushestvennost' vliyaniya oshibok opredeleniya konstant skorostei himicheskih reakcii na fizicheskie parametry modelei molekulyarnyh oblakov, a, znachit, na interpretaciyu nablyudatel'nyh dannyh po takim modelyam.
4.3. Inye raspredeleniya oshibok konstant himicheskih reakcii
Vse ocenki v etoi rabote sdelany v predpolozhenii ravnomernogo raspredeleniya oshibok konstant skorostei himicheskih reakcii vnutri ukazannogo v UMIST 95 diapazona. Na nash vzglyad, predstavlyaet interes, kak izmenyatsya privedennye v rabote rezul'taty v sluchae inogo raspredeleniya oshibok konstant himicheskih reakcii. V svyazi s bol'shimi zatratami mashinnogo vremeni (na raschet 10000 modelei Pentium 4 2,4 GHz 512 Mb memory tratit bolee 70 chasov) nami ne byl proveden podrobnyi analiz etogo voprosa.
Odnako nekotorye ocenki vse zhe byli polucheny. Dlya etogo byl proveden raschet 5000 modelei himicheskoi evolyucii sredy s privedennymi v tablicah 1 i 2 fizicheskimi i himicheskimi parametrami, no s ispol'zovaniem inache izmenennyh failov UMIST 95.
Ris. 6. Raspredelenie obilii HCN v modelyah pri umen'shennom razbrose konstant skorostei himicheskih reakcii
Vse koefficienty sluchainym obrazom ravnomerno var'irovalis' v predelah diapazona 12,5 %. Poluchennye pri etom gistogrammy dlya HCN, a takzhe dlya otnoshenii HCN/HC3N i HCN/HC5N privedeny na risunkah 6, 7 i 8.
Risunki 6,7 i 8 namerenno sdelany v tom zhe masshtabe po osi X, chto i risunok 1, 4 i 5. Vidno, chto harakternyi vid gistogrammy sohranilsya, odnako shirina sushestvenno umen'shilas', chto i sledovalo ozhidat' pri umen'shenii razbrosa znachenii konstant himicheskih reakcii.
Podobnym zhe obrazom vedut sebya raspredeleniya oshibok otnoshenii obilii. Sootvetstvuyushie gistogrammy predstavleny na risunkah 7 i 8.
Ris. 7. Logarifm otnosheniya obilii HCN / HC3N
pri umen'shennoi razbrose konstant skorostei himicheskih reakcii
Ris. 8. Logarifm otnosheniya obilii HC3N / HC5N
pri umen'shennoi razbrose konstant skorostei himicheskih reakcii
Shirina razbrosa otnoshenii umen'shilas' proporcional'no velichine razbrosa konstant himicheskih reakcii. Raspredelenie zhe v celom sohranilo harakternyi vid. Takim obrazom, est' osnovaniya polagat', chto izmenenie raspredeleniya oshibok ne izmenit kardinal'no vyvody, sdelannye v dannoi rabote. V to zhe vremya, osnovanii polagat', chto oshibki opredeleniya konstant himicheskih reakcii men'she, chem ukazano v opisanii UMIST 95, net. Sledovatel'no, dannye, privedennye v punkte 4.3 sleduet rassmatrivat' tol'ko kak teoreticheskuyu ocenku haraktera povedeniya razbrosa obilii i ih otnoshenii pri izmenenii harakteristik razbrosa konstant himicheskih reakcii.
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