Phase Transitions in Astrophysics, from ISM to Planets

May 7, 2017, 9:00 AM → Jun 2, 2017, 6:00 PM Europe/Stockholm

122:026 (Nordita, Stockholm)

Evangelia Ntormousi (CEA/Saclay), Fabio Del Sordo (Yale University and Nordita), Pascal Tremblin (CEA/Saclay), Wladimir Lyra (California State University, JPL)

Venue

Nordita, Stockholm, Sweden

Scope

Phase transitions occur constantly in the interstellar medium and to a large degree define star and planet formation. The transition from atomic to molecular gas sets the initial conditions for star formation, while the formation and destruction mechanisms of dust and other solids is the basis for understanding the origins of planets. This program aims to bring together experts in ISM dynamics, planet formation, exoplanet atmosphere, and planetary ices, from both modeling and observations to study this problem in detail.

The 2017 Nordita Program “Phase Transitions in Astrophysics” will bring together experts from different areas in Astrophysics to discuss scientific topics all across the cosmic range of scales, from interstellar dust and gas, to protoplanetary disks and planetary atmospheres, focusing on the physics of phase transitions.

PTA is a project-oriented meeting . All participants are invited to bring project ideas on the broad subject of phase transitions, and include experts on different fields. Students are especially encouraged to seek collaborations with postdocs and faculties during this program. A minimum stay of one week is required, but longer stay are encouraged.

Students can apply by sending a cv and a short statement about the science that they would like to accomplish while at Nordita (max 1000 words) to fabio@nordita.org . The organizing committee will fully cover the accommodation and travel expenses for the selected students, and will try to cover expenses for the more experienced participants according to the available funds.

Info: fabio@nordita.org

Programme:

The daily schedule will comprise talks, panel discussions and hands-on workshops. Students are particularly encouraged to seek new avenues in their research by collaborating with the post-docs and faculty, and to learn new computational and observational tools in one of the workshops.

Registration is now open!

Monday, May 8

1 The Magnetized and multiphase ISM as seen by Planck

Speaker: Dr Andrea Bracco

Slides Presentation_Bracco_Nordita.pdf

Tuesday, May 9

2 Smooth Particle MHD, method, expectatives and strategies

I will introduce Smoothed Particle Hydrodinamics as a numerical method, focussing particularly on the pros and cons when simulating ISM and accretion discs. Additionally I will comment on MHD implementations that currently successfully implemented.

Speaker: Dr Federico Stasyszyn

Slides FedericoStasyIntroSPMHD.pdf

3 Python installation tutorial

Wednesday, May 10

4 Practical Python for Researchers (1st part)

Speaker: Dr Simon Candelaresi

Slides introduction.pdf

5 Practical Python for Researchers (2nd part)

Speaker: Dr Simon Candelaresi

Slides pythonIntro.pdf

6 Practical Python for Researchers (3rd part): discussion

Slides scientific_python.pdf

Thursday, May 11

7 On the different kinds of superfluid vortices in the interior of neutron stars

Speaker: Dr Giacomo Marmorini

Slides GiacomoMarmoriniNordita170511v2.pdf

Friday, May 12

8 Critical phenomena, nonlinear dynamics and the formation and detection of planets

Speaker: Prof. John Wettlaufer

Slides JohnWettlauferStockholm_PT_May_17.pdf

Monday, May 15

9 50 years of thermal instability : what have we learned ? what are the new questions ?

Speaker: Dr Marc-Antoine Miville-Deschenes

Slides Miville-Deschenes_Thermal_Instability.pdf

Tuesday, May 16

10 Formation and evolution of filaments in the interstellar medium

Speaker: Dr Evangelia Ntormousi

Slides ntormousi_filaments_formation_and_collapse.pdf

Wednesday, May 17

11 The HI turbulence: temperature distribution, buildup of molecular clouds, and ineffective stellar feedback

Speaker: Dr Snezana Stanimirovic

Slides nordita17_snezana.pdf

12 Clustering and dynamic decoupling of dust grains in turbulent molecular clouds

Speaker: Dr Lars Mattsson (Nordita)

Slides LarsMattson_Nordita_program_PTA_2017.pdf

Thursday, May 18

13 Shining Light on the Dark ISM

Speaker: Dr Joanne Dawson

Slides dawson_stockholm.pdf

Friday, May 19

14 The Dark Milky Way: Probing our Galaxy’s Hidden Gas

Many studies have proved the existence of the “dark interstellar medium” (dark ISM) which is not detected by traditional radio emissions from atomic hydrogen (HI) and carbon monoxide (CO) molecules. In recent years, OH has emerged as a powerful indicator of dark-ISM. In this study, we use HI and OH data from the Arecibo Millennium survey (Heiles and Troland 2003) which observed absorption and emission pairs towards 79 extragalatic radio continuum sources. The Λ-doubling transitions of ground-state OH at 1665.402 and 1667.359 MHz were observed along with HI towards 48 of the 79 survey positions. By newly reducing this unpublished data, OH absorption was detected in 23 lines- of-sight, we find that the OH 1665 and 1667 lines satisfy the optically thin assumption with the optical depth τ less than 0.25 and they are in general not in Local Thermal Equilibrium. By comparing the thermal dust data from Planck satellite (Release 1.2) and the Sloan Digital Sky Survey (Schlafly et al. 2011) with HI data from Millennium survey, we confirm the tight linear correlations between optical depth τ353, dust radiance R, reddening E(B-V) and the total proton column density N(H). We estimate the molecular hydrogen column densities N(H2)=1⁄2[N(H)-N(HI)] from these linear relationships and hence the OH abundance ratio XOH=N(OH)/N(H2), for which few literature measurement exist. The XOH ratios derived from the three N(H) proxies are consistent and appear to be constant around 5.0×10-6. Since these results are obtained in a wide ranges of longitude l and latitude b with some sightlines through the Galactic plane, it suggests that OH main lines are excellent tracers of molecular gas in the interstellar medium including regimes where the usefulness of CO is compromised.

Speaker: Van Hiep Nguyen

Slides hiep.pdf

15 Feedback and interactions from low-mass stars in the Coronet cluster

Speaker: Mara Elizabeth Pelayo Baldárrago

Monday, May 22

16 Phase Transition Dynamics of ISM: The Formation of Molecular Clouds and Galactic Star Formation

Magnetohydrodynamics of interstellar medium is remarkably different from that of simple barotropic gas owing to the phase transitions between cold phase and warm phase (and hot phase) that trigger variety of instabilities. Identifications of distinct instabilities in various stages provide us important clues for understanding the saturation levels of turbulent energies and rates of formation and destruction of cold clouds, such as HI clouds and molecular clouds. Recent high- resolution magneto-hydrodynamical simulations of phase transition dynamics with cooling/heating and thermal conduction have shown that the formation of molecular clouds requires multiple episodes of supersonic compression. This finding enables us to create a new scenario of molecular cloud formation as the interacting shells or bubbles in galactic scale, which explains many observational properties such cloud-to-cloud velocity dispersions, accelerating star formation, and very low star formation efficiencies in filamentary molecular clouds. We estimate the ensemble-averaged growth rate of individual molecular clouds, and predict the associated cloud mass function. Cloud-cloud collisions as a mechanism for forming massive stars and star clusters can be naturally accommodated in this scenario. This explains why massive stars formed in cloud-cloud collisions follows the power-law slope of the mass function of molecular cloud cores repeatedly found in low-mass star forming regions.

Speaker: Prof. Shu-ichiro Inutsuka

Slides Inutsuka_NorditaS.pdf

Tuesday, May 23

17 Fragmentation of a Filamentary Molecular Cloud Permeated by Perpendicular Magnetic Field

Speaker: Prof. Tomoyuki Hanawa

Slides t_hanawa.pdf

18 Effects of the multi-phase character of the interstellar medium on the Galactic dynamo

Speaker: Dr Oliver Gressel (Nordita)

Slides ogressel_TurISM.pdf

Wednesday, May 24

19 Reduced gas accretion onto Super-Earths and ice giants

Speaker: Dr Michiel Lambrechts

20 Geophysical test for habitability in icy ocean worlds

Speaker: Dr Steven Vance

Slides VanceNord_20160524.pdf

Thursday, May 25

21 Some aspects of protoplanetary disc formation and evolution

Speaker: Patrick Hennebelle

Friday, May 26

22 Riddles from the AU Microscopii system

AU Microscopii is a nearby red dwarf, belonging to the beta Pictoris moving group. Like beta Pic, AU Mic is famous for its big, edge-on debris disk. Recent high-resolution, multi-epoch imaging of the system has revealed baffling features in the disk in the form of clumps moving at super-Keplerian speed out from the system. Currently, there is no satisfactory explanation for the origin and dynamics of the clumps. In this talk I will review the current facts and hypotheses, and propose a way forward towards solving this mystery.

Speaker: Alexis Brandeker

23 Discussion on NASA Europa mission

Monday, May 29

24 Jupiter internal structure and the first Juno results

Speaker: Dr Yamila Miguel

Slides YM-Jupiter-Nordita.pdf

25 Characterisation of Exoplanets, how to understand their mass, radius, and atmospheric composition

Speaker: Dr Pascal Tremblin

Slides tremblin_pta2017.pdf

Tuesday, May 30

26 Effect of Phase Transitions on Turbulent Transport

Speaker: Prof. Igor Rogachevskii (Ben-Gurion University of the Negev)

Slides Igor-talk.pdf

Wednesday, May 31

27 Detection and characterization of planets around M Dwarfs

M dwarfs are optimal targets to search for potentially habitable planets in the solar neighborhood through the photometric transit method and the analysis of radial velocity timeseries. Spanning almost all the low- mass spectral range, "breaking news" terrestrial planets have been found around some nearby M dwarfs, and they will be the primary follow-up targets for further characterization in the near future. After introducing the state-of.-the-art techniques used to detect those planets, I will focus on some of the most promising by highlighting in particular the challenges posed by stellar activity and spectroscopical observational sampling for a proper characterization of their bulk composition.

Speaker: Dr Mario Damasso

Slides stoccolma_31052017.pdf

28 Disentangling the structures in debris disks: Planets or just gas?

Speaker: Areli Castrejon

Slides CastrjonNordita05-31-17.pdf

Thursday, June 1

29 Implementing a Radially Efficient Poisson Equation Solver to Investigate Tidal Downsizing

Speaker: Mr Vincent Carpenter

30 Convection on Jupiter's icy moons as a consequence of tidal forces

Speaker: Leonardo Cassarà

Slides nordita_present_leonardo_cassara.pdf

31 Solving radiation and hydrodynamics using a moments model

Speaker: Argel Ramírez Reyes

32 Presentation of an all-Mach regime solver

Speaker: Thomas Padioleau

Slides PadioleauPresentation.pdf