本文關(guān)鍵詞： 星際介質(zhì):觀測(cè)目標(biāo)(獵戶座棒狀光子主導(dǎo)區(qū)) 星際介質(zhì):動(dòng)力學(xué)過程 星際介質(zhì):致密云團(tuán) 星際介質(zhì):分子 技術(shù):高分辨率、高譜分辨率觀測(cè) 恒星:恒星形成　出處：《南京大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：我們首次給出亞毫米波射電干涉儀(the Submillimeter Array,SMA)在獵戶座棒狀(OrionBar)光子主導(dǎo)區(qū)(photon-dominatedregion,PDR)塵埃致密云核的高分辨率觀測(cè)結(jié)果,包括1.3毫米塵埃連續(xù)輻射譜,光薄多重躍遷H2CS(6-5)譜線,以及高譜分辨率C34S(4-3)譜線的觀測(cè)。從1.3毫米塵埃連續(xù)輻射譜,我們首次在空間上發(fā)現(xiàn)九個(gè)可以分辨出來的小尺度(0.01-0.02pc)塵埃致密云核,計(jì)算出其質(zhì)量約為0.02-0.24M⊙之間,其氫分子數(shù)密度在3.6 × 105-1.9 × 106 cm-3之間,我們的結(jié)果首次從觀測(cè)上確定了致密成分的確存在于Orion Bar中,驗(yàn)證了長(zhǎng)久以來對(duì)于Orion Bar的確存在小尺度致密成分的猜想。我們同樣首次在Orion Bar中探測(cè)到H2CS分子譜線,兩條para-H2CS(60,6-50,5)和(62,4-52,3)集中在質(zhì)量最大的兩個(gè)致密云核,我們利用這兩條首次發(fā)現(xiàn)的譜線,在假設(shè)局部熱動(dòng)平衡的情況之下,估算致密云核的動(dòng)力學(xué)溫度大約在96 K。高譜分辨率的C34S(4-3)分子譜線給出云團(tuán)的非熱速度彌散在0.19-0.54 km s-1之間,這個(gè)數(shù)值小于氣體的熱運(yùn)動(dòng)(0.59 km s-1),意味著致密云核處在次聲速的物理環(huán)境之下。我們發(fā)現(xiàn),致密云核的質(zhì)量均遠(yuǎn)遠(yuǎn)小于維里質(zhì)量和Bonnor-Ebert(BE)質(zhì)量,意味著它們其實(shí)是非維里化狀態(tài),同時(shí),也意味在理論上預(yù)測(cè),這些云團(tuán)并不會(huì)發(fā)生引力坍縮而形成恒星。若在更強(qiáng)烈的遠(yuǎn)紅外光子的輻射下(Far-Ultraviolet,FUV),致密云核有可能從原先穩(wěn)定存在的狀態(tài)進(jìn)行不同的演化階段,這取決于致密云核的最初柱密度、FUV輻射場(chǎng)強(qiáng)度、最初所處的物理環(huán)境以及致密云核的本質(zhì)屬性。如果致密云核是因?yàn)橥膭?dòng)匯集而形成的暫時(shí)性密度漲落,我們發(fā)現(xiàn)其在強(qiáng)烈的FUV輻射下會(huì)經(jīng)歷一個(gè)激波壓縮的過程,但密度升高的程度卻不能觸發(fā)其引力不穩(wěn)定而塌縮形成恒星。如果致密云核是被云團(tuán)間介質(zhì)壓力束縛下的物理實(shí)體,致密云核質(zhì)量在FUV輻射場(chǎng)的影響下將會(huì)損失5-50%的最初氣體質(zhì)量,但致密云核會(huì)在其熱殼層與FUV輻射場(chǎng)平衡狀態(tài)下,保留其中心質(zhì)量,與熱殼層、云團(tuán)間介質(zhì)維持壓強(qiáng)平衡狀態(tài),更難以塌縮形成恒星。我們?cè)诠浪阒旅茉坪速|(zhì)量的過程,動(dòng)力學(xué)溫度和塵埃光學(xué)不透明度指數(shù)都有著一定的不確定性。深場(chǎng)的H2CO/H2CS譜線觀測(cè)以及多波段的塵埃連續(xù)譜觀測(cè)可以讓我們更加準(zhǔn)確地確定這兩個(gè)物理量,也能讓我們對(duì)Orion Bar中的致密云核演化情況有一個(gè)更為準(zhǔn)確的判斷�？偠灾�,我們這次研究,不僅首次觀測(cè)到Orion Bar在小尺度上的致密成分,而且理論計(jì)算的所有結(jié)果都在預(yù)示著這些Orion Bar里的塵埃致密云核并不會(huì)在FUV輻射場(chǎng)的影響下演化形成恒星。這個(gè)結(jié)果,第一次從觀測(cè)上回答獵戶座棒狀光子主導(dǎo)區(qū)的致密成分是否存在恒星形成活動(dòng)的問題。
[Abstract]:We present for the first time the high-resolution observations of the dense cloud nuclei of dust in the photonic dominant region of Orion Baron (Orion Baron) by the submillimeter wave radio interferometer (Submillimeter Arrayn SMA), including the 1.3mm continuous dust emission spectrum and the thin and multiple gravimetric transition H2CS6-5) lines. And the observation of the high spectral resolution C34SU 4-3) spectral line. From the 1.3mm dust continuous radiation spectrum, we found for the first time in space nine discernible small scale (0.01-0.02pcc) dust dense cloud nuclei, the mass of which is calculated to be about 0.02-0.24M _ (-). The molecular number density of hydrogen is in the range of 3.6 脳 105-1.9 脳 10 ~ 6 cm-3. Our results show for the first time that the dense component exists in Orion Bar for the first time. It has been proved that there is a small scale dense component in Orion Bar for a long time. We have also for the first time detected the H2CS molecular spectral lines in Orion Bar, two para-H _ 2CS _ (606-50 ~ (5)) and a ~ (6224-52) ~ (3)) are concentrated on the two dense cloud nuclei with the highest mass. On the assumption of local thermodynamic equilibrium, we estimate that the kinetic temperature of dense cloud nuclei is about 96k.High spectral resolution C34Sl4-3) the non-thermal velocity dispersion of cloud clusters is between 0.19-0.54 km / s ~ (-1). This is less than the thermal movement of the gas, 0.59 km / s ~ (-1), which means that the dense cloud nucleus is in the physical environment of subsonic velocity. We find that the mass of the dense cloud nucleus is much smaller than that of the Very mass and the Bonnor-EbertBebe mass, which means that they are in a non-virified state. It also means that it is theoretically predicted that these clouds will not collapse into stars by gravitational collapse. If they are exposed to more intense far-infrared photons, the dense cloud nuclei may undergo different stages of evolution from their previously stable states. This depends on the intensity of the initial column density and FUV radiation field of the dense cloud nucleus, the initial physical environment and the essential properties of the dense cloud nucleus. We found that it experienced a shock compression process under intense FUV radiation, but the increase in density did not trigger its gravitational instability and collapse to form a star. If the dense cloud nucleus is a physical entity bound by the pressure of the intercloud medium, The mass of dense cloud nuclei will lose 5-50% of the initial gas mass under the influence of the FUV radiation field, but the dense cloud nuclei will retain their central mass in the equilibrium state of the hot crust and the FUV radiation field, and maintain the pressure equilibrium state with the hot crust and the medium between the cloud clusters. It's harder to collapse into stars. We're estimating the mass of dense cloud nuclei, Both the kinetic temperature and the opacity index of dust are uncertain. The deep field H2CO / H2CS spectral line observation and the multi-band dust continuous spectrum observation can help us to determine these two physical quantities more accurately. It also allows us to have a more accurate assessment of the evolution of dense cloud nuclei in Orion Bar. In summary, we have not only observed the compact components of Orion Bar on a small scale for the first time in this study. And all the theoretical calculations indicate that the dense cloud nuclei in the Orion Bar do not evolve into stars under the influence of the FUV radiation field. For the first time, the question of whether the dense components of Orion rod-shaped photonic dominant region are active in star formation is answered from observations for the first time.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P151

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