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Susanne Pfalzner Susanne Pfalzner Max-Planck-Institut für Radioastronomie 1995 confirmed by first resolved disc and first exoplanet discovery Nowadays: large surveys to monitor Jupiter millions of stars (Corot, Kepler) Saturn upcoming TESS, Plato Neptune Uranus Machinelearningalgorithms Earth Venus used to find periodic Mars modulations of light curves Mercury Many differences to solar system: • Many eccentric, inclinedorbits • Planetary systems much denser pacKed • Most abundant planets: Super-Earth or Mini-Neptunes M. Mayor & D. Queloz(Nature, 1995) ¡ Most planets and planetary systems differ considerably from our own solar system ¡ About 50% of stars are not single, but binaries. Why? How do they form? ¡ Many low mass stars and few high mass stars. Why? High-mass stars always binaries or higher order systems. Why? ¡ ... Stars rarely form in isolation, These groups contain a dozen stars ... but mostly form in clusters Lada & Lada (2003), Porras (2003) ...to a few 10 000 stars Orion Nebula Cluster Quintupletts Ori clustercluster How does the cluster environment influence star and planet formation? 1. What is the typical cluster environment? 2. Does the cluster environment influence the properties of the stars, discs and planets? What do observations tell us? Photographic plates First objective, permanent record of astronomical phenomena Direct image • Long exposure times possible; faint objects detectable • Large format: many surveys carried out Efficiency around 1% (most of the photons lost)! • Extremely high efficiency at redder wavebands -- almost 100%! • Limiting magnitudes increased by four to five magnitudes! Output is digital Processed data Clearing from noise • Removal of instrumental signatures • Masking of stellar halos, satellite tracks, etc. • Photometric and astrometric calibration • Atmospheric changes The bigger the telescope the better the resolution ... ¡ ...but there is a limit at about 100m ALMA Problem: youhave to fillin gaps by interpolation SKA SKA will produce per day as many data as DESY in a year Protoplanetary Disk of HL Tauri CARMA image ALMA image Stars rarely form in isolation, but mostly form in clusters Lada & Lada (2003), Porras (2003) Orion Nebula Cluster optical infra-red Stars do mostly form not in isolation, Composite picture Data at wavelength invisible for human eye are shown at different colors M17 ESA Second data release of Gaia 0.9 billion individual CCD observations per day •celestial positions 1.3 billion sources •stellar effective temperature, extinction, reddening, and radius and luminosity for 161 million sources Each of these needs multiple data processing Combining Data processing different Final wavelength image Combining singledishes Data Machine reduction learning Original data Photographer Data Scientist T Theoretician ? Observations provide only snapshots at a certain moment in time Theory (simulation) must create time sequence Several theories – Which is the right one? Predictions from theory tested by observations Challenges, like in other fields • steep spatial gradients, complex geometries, etc. (1 AU – 20 000 000 AU) AU = astronomical unit distance Sun -- Earth But also, • often very different time scales years – several million years (Myr) • No direct comparison with experiment Comparison betWeen TWO SIMULATIONS observational data theoretical models „It looks the same“, is not enough! How does the cluster environment influence star and planet formation? 1. What is the typical cluster environment? 2. Does the cluster environment influence the properties of the stars, discs and planets? General opinion: Multitude of different clusters Surprise: Upp Cen-Crux I Lac 1 Two types of massive clusters Ori 1a Low Cen-Crux Upp Sco IC 1805 Ori 1c ¡ Compact massive clusters 10 loose clusters NGC 7380 NGC 6611 Ori 1b ¡ NGC 2244 CygOB2 Loose massive clusters RSGC03 Pfalzner A&A Highlight 2009 RSGC02 [pc] χ Per eff Quintuplett h Per r DSB2003 RSGC01 Questions: 1 Westerlund 1 Westerlund 2 NGC 3603 compact clusters ¡ How do such clusters form? Trumpler 14 Arches ¡ How do they develop? 1 10 Pfalzner 2009 Age [Myr] Massive clusters: Highly dynamical environments embedded expulsion expansion Stellar density ¡ Several 10 000 stars form in ~ 1Myr ¡ Clusters expandby ~ a factor 10 within 5-10 Myr How do massive clusters Conditions at end of What drives massive form? star formation? cluster expansion? Forbidden area How do massive clusters Conditions at end of What drives massive form? star formation? cluster expansion? Pfalzner et al. 2016 Upp Cen-Crux I Lac 1 Ori 1a Low Cen-Crux Upp Sco IC 1805 Ori 1c 10 loose clusters NGC 7380 NGC 6611 Ori 1b NGC 2244 CygOB2 RSGC03 RSGC02 [pc] χ Per eff Quintuplett h Per r DSB2003 RSGC01 1 Westerlund 1 Westerlund 2 NGC 3603 compact clusters Trumpler 14 Arches 1 10 Age [Myr] Loose clusters – associations Upp Cen-Crux I Lac 1 Large massloss, strong expansion Ori 1a Low Cen-Crux Upp Sco IC 1805 Gas expulsion Ori 1c 10 loose clusters NGC 7380 ~30% of gas converted into stars NGC 6611 Ori 1b NGC 2244 CygOB2 RSGC03 (Star formation efficiency = SFE) RSGC02 [pc] χ Per eff Quintuplett h Per r Compact clusters – open clusters DSB2003 RSGC01 1 Westerlund 1 Little massloss, strong expansion Westerlund 2 compact clusters NGC 3603 Stellar ejections Trumpler 14 Arches > 60% star formation efficiency 1 10 Age [Myr] Pfalzner & KacmareK (A&A 2013a, b) How do massive clusters Conditions at end What drives massive form? of star formation? cluster expansion? Simple analytical model Loose clusters 1-3 pc ~ 30% SFE gas expulsion with spatial varying SFE Compact cl. 0.1-0.3 pc > 60% SFE ejection How does the cluster environment influence star and planet formation? 1. What is the typical cluster environment? 2. Does cluster environment influence the properties of the stars, discs and planets? • external photo-evaporation by the massive stars Only happens after gas has disappeared • gravitational interactions important already during cluster formation Richling & Yorke 1998, Alexander 2008, Anderson et al. 2013 Heller 1995, Pfalzner et al. 2006, Olczak et al. 2010, Steinhausen et al. 2014, Vincke & Pfalzner 2016, Winter et al. 2018, Vincke & Pfalzner 2018 Influenced properties Over 5000 parameter • Disc mass combinations studied so far • Disc size • Mass distribution • Accretion rate Star-disc simulations Effect of cluster on star-disc systems Cluster simulations Disc fraction vs. cluster age low-mass cluster extended cluster compact cluster external processes play a role, but do not dominate disc dispersal mainly by internal processes Olczak et al. 2012, Olczak et al. 2014, Pfalzner 2014 Initial conditions 4,000 stars rhm = 1.3 pc temb = 2 Myr Vincke et al. 2015 Initial conditions 32,000 stars Rhm = 0.2 pc temb = 0 Myr Vincke & Pfalzner 2016 Median disc size in compact clusters extended significantly smaller than in extended clusters clusters The longer the embedded phase, the smaller the discs due to more encounters compact clusters Compact clusters 1 Myr embedded: more than half of all discs destroyed Vincke & Pfalzner subm. Associations • Small influence on disc frequency, • but disc size restricted to approx. 100 AU ALMA image of HL TauriCompact clusters ¡ Strong influence on disc frequency and size ¡ Probably smaller planetary systemsin open clusters All planets lie nearly in a plane and on nearly circular orbits 8927574.png Transneptunian objects High eccentrcities High inclinations ¡ Cut-off in mass beyondNeptune: 1000 fewer objects than expected ¡ Most objects have high inclinations, eccentric orbits • TNOs were originally between Saturn and Neptune • Scattered outwards due to movement of planets Sedna 2012 VP113 Perhelion: 76 AU 80 AU Apelion: 937 AU 446 AU Period: 11400 yr 4274 yr Eccentricity: 0.8527 0.694 High eccentricity NOT caused by planets (Gaidos et al. 2005) Possible explanation: Fly-by 06.06.18 Fly-by ofstar with Mass: 0.5 Msun Perihelion distance: 100 AU Inclination: 600 Solar disc: > 100 AU reproduces ¡ 30 AU drop ¡ Kuiper belt ¡ Sednoids and ... Pfalzner et al. subm. Apj Jupiter 100 Saturn Neptune Uranus 10 Primordial Neptune Mass (Earth mass) Ninth Planet Neptune is more massive than Uranus1 0 10 20 30 40 50 60 70 Distance to Sun (AU) outward inward Natural explanation for Neptune‘smass being higher than that of Uranus Observations nowadays advances Data science Comparing simulations and observation essential for scientific progress Star and planet formation happens in cluster environment Two types of clusters Associations: Small influence on disc frequency, large influence on disc size Compact clusters: Strong influence on disc frequency and disc size Relevant for solar system: A fly-by scenario can explain outer solar system features.
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