語系:
繁體中文
English
說明(常見問題)
回圖書館首頁
手機版館藏查詢
登入
回首頁
到查詢結果
[ subject:"Astrophysics." ]
切換:
標籤
|
MARC模式
|
ISBD
Turbulent, Molecular Clouds Regulate...
~
Raskutti, Sudhir.
FindBook
Google Book
Amazon
博客來
Turbulent, Molecular Clouds Regulated by Radiation Feedback.
紀錄類型:
書目-電子資源 : Monograph/item
正題名/作者:
Turbulent, Molecular Clouds Regulated by Radiation Feedback./
作者:
Raskutti, Sudhir.
出版者:
Ann Arbor : ProQuest Dissertations & Theses, : 2016,
面頁冊數:
247 p.
附註:
Source: Dissertation Abstracts International, Volume: 78-04(E), Section: B.
Contained By:
Dissertation Abstracts International78-04B(E).
標題:
Astrophysics. -
電子資源:
http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10167607
ISBN:
9781369219555
Turbulent, Molecular Clouds Regulated by Radiation Feedback.
Raskutti, Sudhir.
Turbulent, Molecular Clouds Regulated by Radiation Feedback.
- Ann Arbor : ProQuest Dissertations & Theses, 2016 - 247 p.
Source: Dissertation Abstracts International, Volume: 78-04(E), Section: B.
Thesis (Ph.D.)--Princeton University, 2016.
Radiation feedback from stellar clusters is expected to play a key role in setting the rate and efficiency of star formation in giant molecular clouds (GMCs) and across whole galaxies. In particular, stellar radiation may quench star formation by driving outflows and unbinding stellar clusters. To investigate how radiation forces influence realistic clouds, we have conducted a series of simulations employing the Hyperion radiation hydrodynamics solver, considering the regime that is optically thick to ultraviolet and optically thin to infrared radiation. Our model clouds cover initial surface densities between Sigmacl,0 ∼ 10--300 M[special character omitted] pc-2, with varying initial turbulence and magnetic field strength (Bz,0). We follow them through turbulent, self-gravitating collapse, formation of star clusters, and cloud dispersal by stellar radiation. All our models display a lognormal distribution of gas surface density Sigma as seen by both the observer and the central cluster. For an initial virial parameter alphavir,0 = 2$, the lognormal standard deviation is sigmalnSigma = 1--1.5 and the star formation rate (SFR) coefficient epsilonff,rho = 0.3--0.5, both of which are sensitive to turbulence, and magnetic fields, but not radiation feedback. Embedded stars are more centrally concentrated than the gas so that above Sigmacl,0 ∼ 60 M[special character omitted] pc-2, the star cluster remains intact even when surrounding gas is dispersed. The net star formation efficiency depends primarily on the distribution of Eddington ratios in the cloud and therefore increases with Sigmacl,0 and decreases with both alpha vir,0 and Bz,0. This also has implications for outflows, since low surface density regions may be driven outwards to nearly 10 times their initial escape speed (vesc). However, the overall efficiency of momentum injection to the gas is reduced because much of the radiation escapes and irrespective of Sigmacl,0 , the mean outflow velocity is approximately twice v esc. Unless GMCs are highly magnetized and turbulent, the lognormal structure of gas modulates the effect of radiative feedback in disrupting clouds, so that it cannot alone explain the low observed galactic SFR.
ISBN: 9781369219555Subjects--Topical Terms:
535904
Astrophysics.
Turbulent, Molecular Clouds Regulated by Radiation Feedback.
LDR
:03101nmm a2200277 4500
001
2122506
005
20170922124922.5
008
180830s2016 ||||||||||||||||| ||eng d
020
$a
9781369219555
035
$a
(MiAaPQ)AAI10167607
035
$a
AAI10167607
040
$a
MiAaPQ
$c
MiAaPQ
100
1
$a
Raskutti, Sudhir.
$3
3284477
245
1 0
$a
Turbulent, Molecular Clouds Regulated by Radiation Feedback.
260
1
$a
Ann Arbor :
$b
ProQuest Dissertations & Theses,
$c
2016
300
$a
247 p.
500
$a
Source: Dissertation Abstracts International, Volume: 78-04(E), Section: B.
500
$a
Adviser: Eve C. Ostriker.
502
$a
Thesis (Ph.D.)--Princeton University, 2016.
520
$a
Radiation feedback from stellar clusters is expected to play a key role in setting the rate and efficiency of star formation in giant molecular clouds (GMCs) and across whole galaxies. In particular, stellar radiation may quench star formation by driving outflows and unbinding stellar clusters. To investigate how radiation forces influence realistic clouds, we have conducted a series of simulations employing the Hyperion radiation hydrodynamics solver, considering the regime that is optically thick to ultraviolet and optically thin to infrared radiation. Our model clouds cover initial surface densities between Sigmacl,0 ∼ 10--300 M[special character omitted] pc-2, with varying initial turbulence and magnetic field strength (Bz,0). We follow them through turbulent, self-gravitating collapse, formation of star clusters, and cloud dispersal by stellar radiation. All our models display a lognormal distribution of gas surface density Sigma as seen by both the observer and the central cluster. For an initial virial parameter alphavir,0 = 2$, the lognormal standard deviation is sigmalnSigma = 1--1.5 and the star formation rate (SFR) coefficient epsilonff,rho = 0.3--0.5, both of which are sensitive to turbulence, and magnetic fields, but not radiation feedback. Embedded stars are more centrally concentrated than the gas so that above Sigmacl,0 ∼ 60 M[special character omitted] pc-2, the star cluster remains intact even when surrounding gas is dispersed. The net star formation efficiency depends primarily on the distribution of Eddington ratios in the cloud and therefore increases with Sigmacl,0 and decreases with both alpha vir,0 and Bz,0. This also has implications for outflows, since low surface density regions may be driven outwards to nearly 10 times their initial escape speed (vesc). However, the overall efficiency of momentum injection to the gas is reduced because much of the radiation escapes and irrespective of Sigmacl,0 , the mean outflow velocity is approximately twice v esc. Unless GMCs are highly magnetized and turbulent, the lognormal structure of gas modulates the effect of radiative feedback in disrupting clouds, so that it cannot alone explain the low observed galactic SFR.
590
$a
School code: 0181.
650
4
$a
Astrophysics.
$3
535904
690
$a
0596
710
2
$a
Princeton University.
$b
Astrophysical Sciences.
$3
3193121
773
0
$t
Dissertation Abstracts International
$g
78-04B(E).
790
$a
0181
791
$a
Ph.D.
792
$a
2016
793
$a
English
856
4 0
$u
http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10167607
筆 0 讀者評論
館藏地:
全部
電子資源
出版年:
卷號:
館藏
1 筆 • 頁數 1 •
1
條碼號
典藏地名稱
館藏流通類別
資料類型
索書號
使用類型
借閱狀態
預約狀態
備註欄
附件
W9333122
電子資源
01.外借(書)_YB
電子書
EB
一般使用(Normal)
在架
0
1 筆 • 頁數 1 •
1
多媒體
評論
新增評論
分享你的心得
Export
取書館
處理中
...
變更密碼
登入