-
Notifications
You must be signed in to change notification settings - Fork 0
/
index_research.html~
122 lines (89 loc) · 6.27 KB
/
index_research.html~
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
<!DOCTYPE HTML>
<!--
Story by HTML5 UP
html5up.net | @ajlkn
Free for personal and commercial use under the CCA 3.0 license (html5up.net/license)
-->
<html>
<head>
<title>Research</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<link rel="stylesheet" href="assets/css/main.css" />
</head>
<body>
<!-- Wrapper -->
<div id="wrapper" class="divided">
<!-- One -->
<section class="banner style1 orient-left content-align-left image-position-right fullscreen onload-image-fade-in onload-content-fade-right">
<div class="content">
<h1>My research</h1>
<p class="major"> My research focuses on using hydrodynamic simulations to study how the diffuse gas of the Interstellar medium (ISM) is able to condense into filaments and cores, leading to the formation of stars. I'm especially interested in the interplay between gravity and turbulence in dense gas filaments and the role this has on fragmentation. I am also interested in the chemical evolution of the ISM as gas moves from the diffuse gas into dense cores, and how this influences how these structures are seen when observed with dust and molecular line tracers.</p>
</div>
</section>
<!-- Two -->
<section class="spotlight style1 orient-right content-align-left image-position-center onscroll-image-fade-in" id="first">
<div class="content">
<h2>Filament dynamics</h2>
<p>
Filaments are intimately linked to the star formation process; however, their internal dynamics and the mechanism by which they fragment to form stars is not well understood. Using three-dimensional hydrodynamic simulations I study the roles that gravity, turbulence and magnetic fields have on the filament evolution. I use the SPH and meshless code <a href = "http://gandalfcode.github.io/"> GANDALF </a> and the moving-mesh code <a href = "https://www.h-its.org/tap-software-en/arepo/"> AREPO </a>
</p>
</div>
<div class="image">
<img src="images/mom0.png" alt="" />
</div>
</section>
<!-- Three -->
<section class="spotlight style1 orient-left content-align-left image-position-center onscroll-image-fade-in">
<div class="content">
<h2> Filament fragmentation </h2>
<p>
Filament fragmentation is an important process which governs how gas collects into dense cores. Previous models have made the assumption that the filament is in hydrostatic equilibrium; I have developed non-equilibrium models which show that the gas accretion onto a filament plays an important role in fragmentation. Moreover, degree of turbulence within the accretion material greatly affects the fragmentation of the filament. Filaments which are gravity dominated fragment in a two-tier manner similar to the observed fragmentation of the Orion Integral Shaped Filament. When turbulence dominates in the accretion material, the filament first fragments into sub-filaments and then into cores which produce stars. </p>
<a href=http://adsabs.harvard.edu/abs/2016MNRAS.458..319C" class="button"> Paper 1</a> <a href=http://adsabs.harvard.edu/abs/2017MNRAS.468.2489C" class="button"> Paper 2</a> <a href=http://adsabs.harvard.edu/abs/2019arXiv190106205C" class="button"> Paper 3</a>
</div>
<div class="image">
<img src="images/channel.gif" alt="" />
</div>
</section>
<!-- Four -->
<section class="spotlight style1 orient-right content-align-left image-position-center onscroll-image-fade-in">
<div class="content">
<h2> Filament collapse</h2>
<p>
Due to their geometry, the gravitational collapse of a filament differs significantly from that of a spherical cloud. The two longitudinal ends of the filament are rapidly accelerated towards the filament's centre and act as snowploughs, accreting gas as they travel. The collapse is also much longer than that of an equally dense sphere; I have developed an equation for the timescale of the collapse, analogous to the spherical free-fall time. This makes filaments an excellent site for star formation as the structure is more long-lived than a spherical clump and the massive and dense snowplough end regions can rapidly fragment. The Musca filament exhibits the signs of filamentary collapse.
</p>
<a href=http://adsabs.harvard.edu/abs/2015MNRAS.449.1819C" class="button"> Paper </a>
</div>
<div class="image">
<img src="images/filament.png" alt="" />
</div>
</section>
<!-- Five -->
<section class="spotlight style1 orient-left content-align-left image-position-center onscroll-image-fade-in">
<div class="content">
<h2>Astrochemistry and synthetic observations</h2>
<p>
Observations of molecular clouds in the ISM are done using dust and molecular line emission/absorption. If a modeller wishes to compare their simulations to observation it is therefore important to understand the distribution of these tracers, this is done using astrochemical models and synthetic observations. Using synthetic observations of C<sup>18</sup>O of filaments I have shown that the observations of velocity-coherent "fibres" in Taurus are intimately linked to the accretion of material onto the filament. Moreover, I show that extreme care must be taken when using velocity coherent features such as fibres to constrain the underlying density substructure of filaments.
</p>
<a href = "http://adsabs.harvard.edu/abs/2018arXiv180608564C" class="button"> Paper </a>
</div>
<div class="image">
<img src="images/rotation.gif" alt="" />
</div>
</section>
<!-- Footer -->
<footer class="wrapper style1 align-center">
<div class="inner">
<p>© Seamus Clarke. Page template: <a href="https://html5up.net">HTML5 UP</a>.</p>
</div>
</footer>
</div>
<!-- Scripts -->
<script src="assets/js/jquery.min.js"></script>
<script src="assets/js/jquery.scrollex.min.js"></script>
<script src="assets/js/jquery.scrolly.min.js"></script>
<script src="assets/js/skel.min.js"></script>
<script src="assets/js/util.js"></script>
<script src="assets/js/main.js"></script>
</body>
</html>