Select Page

Research digital skills training 2021

Planet hunting

Philip Yock, Department of Physics

Home • Projects • Planet hunting

Using microlensing to detect planets

Astronomers and philosophers have long thought about planets like ours, possibly inhabited, orbiting the stars of the night sky. Assuming the solar system is typical, a rough estimate of planets in the Milky Way would be around one trillion. Confirming this prediction has, however, turned out to be far from trivial.

The first planet to be found orbiting a star like the Sun was not found until 1995. The reason is straightforward. If we attempt to see a planet like Earth orbiting a star like the Sun, we need to search very close to the star, because even the nearest stars are at vast distances. The proximity of the planet to its host star implies it is lost in the glare of the star. For this reason, indirect detection methods are required.

New Zealand astronomers have been largely responsible for pioneering a planet detection technique which utilises the bending of light by the gravitational field, an effect that was predicted by Einstein early last century.

The method is illustrated as Figure 1. If two stars are aligned, as seen from Earth, then the nearer one acts as a gravitational “lens” of the more distant one. If planets orbit the lens star, their gravitational fields can perturb the lensing action to a detectable degree.

NZ astronomers using the microlensing technique are members of international collaborations known variously as MOA, MicroFUN and PLANET. Of these groups, MOA has the largest presence in New Zealand with members from Auckland, Massey and Canterbury universities.

Figure 1: The bending of light in the gravitational field of a star leads to the formation of an Einstein ring. The size of the Einstein ring is comparable to that of typical planetary systems. It is therefore possible for planets orbiting the “lens” star to betray their presence by perturbing the ring.
Figure 2. Series of over one hundred trials showing colour coded chi square values that was carried out in one night’s computing on the Pan. The results would have taken some months to obtain on a single PC. They were published in a paper on the detectability of Earth-like planets that appeared in the Monthly Notices of the Royal Society,
Vol 431, pp 2975-2985 (2013).

Simulating light rays

All stars are in motion. The formation of an Einstein ring is therefore a transient phenomenon only, visible for a matter of days. As two stars move into and out of alignment, the effect grows and subsequently diminishes. The effect of planets on the lensing process is most easily seen when the alignment is highest. The NZ groups have made good use of this seemingly self-evident effect. Analysing data on these “microlensing events” is not straightforward. It is very much a multi-parameter problem with at least five, ten or fifteen parameters that need to be varied to find the best match to the data.

At the University of Auckland a ‘ray shooting’ method has been devised. In this, simulated light rays are shot through an assumed lens system configuration, rather like optical lens designers do, and the computed image is compared with observation. Very large numbers of trials are made especially for a lens systems with multiple planets. Trials are made one at a time in a procedure that is parallelisable and ideally run on clusters of personal computers (PCs). The members of the MOA group at the University of Auckland have been very fortunate to receive much assistance with this. More recently, the Pan cluster became available which was used successfully by MSc student Matthew Freeman and summer scholar Charlotte Airey with assistance provided by Sina Masoud-Ansari. Some of their results appear Figure 2.

Future plans

The international microlensing community currently operate a growing number of telescopes, currently in excess of twenty, to monitor microlensing events. The quality of data being obtained with these telescopes is growing continuously and also the sophistication of the data analysis. Already several exotic discoveries have been made including the discovery of a large population of “free-floating” planets roaming interstellar regions in the Milky Way.

Further information

MOA: www.phys.canterbury.ac.nz/moa
MicroFUN: www.astronomy.ohio-state.edu/~microfun
PLANET: www.planet-legacy.org++

The telescopes used by the MOA group at the Mt John University Observatory in Canterbury. MOA is a Japan/NZ collaboration, and the nearer of the two telescopes shown above was supplied by Japan. With a diameter of 1.8m, it is the world’s largest telescope dedicated to microlensing.

See more case study projects

Data maturity project in High Value Nutrition, National Science Challenge

Data maturity project in High Value Nutrition, National Science Challenge

Haka on the move: sport circuits and cultural performance 

Haka on the move: sport circuits and cultural performance 

Proteins under a computational microscope: designing in-silico strategies to understand and develop molecular functionalities in Life Sciences and Engineering

Proteins under a computational microscope: designing in-silico strategies to understand and develop molecular functionalities in Life Sciences and Engineering

Remote temperature monitoring to reduce the spread of COVID-19

Remote temperature monitoring to reduce the spread of COVID-19

COVID-19 exponential growth visualisation

COVID-19 exponential growth visualisation

Developing virtual capabilities for the Science Payload Operations Centre

Developing virtual capabilities for the Science Payload Operations Centre

Hosting visualisation and analytics tools for COVID-19 studies

Hosting visualisation and analytics tools for COVID-19 studies

Exploring perceptions towards climate change over time on Twitter

Exploring perceptions towards climate change over time on Twitter

Coastal image classification and nalysis based on convolutional neural betworks and pattern recognition

Coastal image classification and nalysis based on convolutional neural betworks and pattern recognition

Calcium signalling in salivary gland acinar cells

Calcium signalling in salivary gland acinar cells

Anti-corruption regulations for promoting socially responsible practices

Anti-corruption regulations for promoting socially responsible practices

Determinants of translation efficiency in the evolutionarily-divergent protist Trichomonas vaginalis

Determinants of translation efficiency in the evolutionarily-divergent protist Trichomonas vaginalis

Analysing text data by time-series feature engineering

Analysing text data by time-series feature engineering

An investigation into Leap Motion device for “gesture-as-sign”

An investigation into Leap Motion device for “gesture-as-sign”

Antibiotic resistance and the “end of modern medicine ”

Antibiotic resistance and the “end of modern medicine ”

Develop short-term eruption warning systems for Whakaari and other volcanoes

Develop short-term eruption warning systems for Whakaari and other volcanoes

Evenly spaced observation fields from irregularly sampled data in the Southern Ocean

Evenly spaced observation fields from irregularly sampled data in the Southern Ocean

Measuring impact of entrepreneurship activities on students’ mindset, capabilities and entrepreneurial intentions

Measuring impact of entrepreneurship activities on students’ mindset, capabilities and entrepreneurial intentions

Using Zebra Finch data and deep learning classification to identify individual bird calls from audio recordings

Using Zebra Finch data and deep learning classification to identify individual bird calls from audio recordings

NETwork! analysis in cancer – managing genomics research data and building a repository workflow

NETwork! analysis in cancer – managing genomics research data and building a repository workflow

The Coronary Atlas – data processing workflow optimisation

The Coronary Atlas – data processing workflow optimisation

3D visualisation of indigenous burial site in Roonka

3D visualisation of indigenous burial site in Roonka

Automated measurement of intracranial cerebrospinal fluid volume and outcome after endovascular thrombectomy for ischemic stroke

Automated measurement of intracranial cerebrospinal fluid volume and outcome after endovascular thrombectomy for ischemic stroke

A new ‘stratigraphy’: interpreting object relationships with 3D point densities

A new ‘stratigraphy’: interpreting object relationships with 3D point densities

Towards the use of deep learning techniques for storm surge prediction

Towards the use of deep learning techniques for storm surge prediction

Using simple models to explore complex dynamics: A case study of macomona liliana (wedge-shell) and nutrient variations

Using simple models to explore complex dynamics: A case study of macomona liliana (wedge-shell) and nutrient variations

Development of Machine Learning methodology for genomic research

Development of Machine Learning methodology for genomic research

An Archaeological database for threatened North Island rock art in New Zealand

An Archaeological database for threatened North Island rock art in New Zealand

Presence: distributed mixed reality learning environment

Presence: distributed mixed reality learning environment

Digital video and the early learning lab

Digital video and the early learning lab

Publishing the Bay of Island Bottlenose dolphin catalogue

Publishing the Bay of Island Bottlenose dolphin catalogue

Modelling the diurnal cycle* of winds and clouds

Modelling the diurnal cycle* of winds and clouds

Presence: distributed mixed reality learning environment

Presence: distributed mixed reality learning environment

Using research virtual machines to analyse fMRI datasets

Using research virtual machines to analyse fMRI datasets

Genomic Virtual Lab (GVL) as a bioinformatics training platform

Genomic Virtual Lab (GVL) as a bioinformatics training platform

SwiftLaTeX- Exploring web-based true WYSIWYG editing for digital publishing

SwiftLaTeX- Exploring web-based true WYSIWYG editing for digital publishing

Climate change impacts on weather-related hazards

Climate change impacts on weather-related hazards

Understanding tumour evolution through augmented reality

Understanding tumour evolution through augmented reality

Myocardial motion tracking and strain calculation using Deep Learning networks

Myocardial motion tracking and strain calculation using Deep Learning networks

OnTask pilot at the Centre for Learning and Research in Higher Education

OnTask pilot at the Centre for Learning and Research in Higher Education

Visualising the University campus in 3D

Visualising the University campus in 3D

Visualising protein interaction

Visualising protein interaction

Biological heritage National Science Challenge eDNA virtual hub

Biological heritage National Science Challenge eDNA virtual hub

Interactive AR art – Project Gordon

Interactive AR art – Project Gordon

1-D numerical models of post-glacial river evolution

1-D numerical models of post-glacial river evolution

Mathematically modelling gastrointestinal electrical activity

Mathematically modelling gastrointestinal electrical activity

3D Cryo-EM reconstructions of macromolecular complexes

3D Cryo-EM reconstructions of macromolecular complexes

Engine knock in a spark-ignition engine with hydrogen supplementation

Engine knock in a spark-ignition engine with hydrogen supplementation

The complex unsteady flow within a fluid-filled annulus and its transition to turbulence

The complex unsteady flow within a fluid-filled annulus and its transition to turbulence

Using data mining for digital ink recognition

Using data mining for digital ink recognition

The landscape costs of brushtail possum dispersal

The landscape costs of brushtail possum dispersal

Accelerating the discovery of natural products made by orphan megasynthases

Accelerating the discovery of natural products made by orphan megasynthases

Improving the short term precipitation forecasts for New Zealand

Improving the short term precipitation forecasts for New Zealand

Finding genetic variants responsible  for human disease hiding in the universe of benign variants

Finding genetic variants responsible for human disease hiding in the universe of benign variants

Revealing key processes in enzyme efficiency through high performance computing

Revealing key processes in enzyme efficiency through high performance computing

3D Electromagnetic modeling and simulation using heterogeneous computing

3D Electromagnetic modeling and simulation using heterogeneous computing

Hemodynamics in the microcirculation

Hemodynamics in the microcirculation

Putting turbulence to work

Putting turbulence to work

Why are some molecules drugs?

Why are some molecules drugs?

Bayesian additive regression trees  vs logistic regression – estimation of propensity scores

Bayesian additive regression trees vs logistic regression – estimation of propensity scores

Fully coupled thermo-hydro-mechanical modelling of permeability enhancement by the finite element method

Fully coupled thermo-hydro-mechanical modelling of permeability enhancement by the finite element method

Modelling dispersal and ecological competition in a statistical phylogeographic framework

Modelling dispersal and ecological competition in a statistical phylogeographic framework

Studying the shape and the size of the universe

Studying the shape and the size of the universe

Planet hunting

Planet hunting

Simulating quantum mechanics on high performance computing cluster

Simulating quantum mechanics on high performance computing cluster

Multiscale modelling of saliva secretion

Multiscale modelling of saliva secretion

Modelling dual reflux pressure swing adsorption (DR-PSA) units for gas separation in natural gas processing

Modelling dual reflux pressure swing adsorption (DR-PSA) units for gas separation in natural gas processing

Improving the treatment of heart disease

Improving the treatment of heart disease

Estimating migration rates in the budding yeast Saccharomyces cerevisiae

Estimating migration rates in the budding yeast Saccharomyces cerevisiae

Number theoretic algorithms in cryptography

Number theoretic algorithms in cryptography

Molecular phylogenetics uses genetic data to reconstruct the evolutionary history of individuals, populations or species

Molecular phylogenetics uses genetic data to reconstruct the evolutionary history of individuals, populations or species

Phylogeny and phylogeography of the family kyphosidae (Perciformes: teleostei)

Phylogeny and phylogeography of the family kyphosidae (Perciformes: teleostei)

Testing what cosmic inflation really predicts

Testing what cosmic inflation really predicts

Multigene environmental DNA data analysis for New Zealand genomic observatory

Multigene environmental DNA data analysis for New Zealand genomic observatory

Finding genetic variants responsible for human disease hiding in universe of benign variants

Finding genetic variants responsible for human disease hiding in universe of benign variants

BEAST, Bayesian evolutionary analysis sampling trees

BEAST, Bayesian evolutionary analysis sampling trees

The formation of surface archaeological deposits in arid Australia

The formation of surface archaeological deposits in arid Australia

Statistical modelling of carryover effects after cessation of treatments

Statistical modelling of carryover effects after cessation of treatments

High-resolution cryo-electron microscopy of protein complexes and machines

High-resolution cryo-electron microscopy of protein complexes and machines

ARCI, archaeology eResearch collaboration initiative

ARCI, archaeology eResearch collaboration initiative

Optimisation of blades on large wind turbines with individual pitch control and trailing edge flaps

Optimisation of blades on large wind turbines with individual pitch control and trailing edge flaps

Quality of care and outcomes in children with cleft lip and/or palate

Quality of care and outcomes in children with cleft lip and/or palate

Geographic and temporal information retrieval on massive document collections

Geographic and temporal information retrieval on massive document collections

Homodynamics in the microcirculation

Homodynamics in the microcirculation

Processing structure-from-motion photogrammetry on the cluster

Processing structure-from-motion photogrammetry on the cluster

Computational investigation of catalysis mechanisms for polyurethane synthesis

Computational investigation of catalysis mechanisms for polyurethane synthesis

Virtual childhood obesity prevention laboratory

Virtual childhood obesity prevention laboratory

Giving Pacific research greater reach

Giving Pacific research greater reach

Development of novel waveguides  in the terahertz (THz) region

Development of novel waveguides in the terahertz (THz) region

Modelling of costs of diets  by INFORMAS

Modelling of costs of diets by INFORMAS

Foodback

Foodback

Finite element method code for  modelling biological cells

Finite element method code for modelling biological cells

The future of memory: Neuroimaging memory and imagination with functional MRI

The future of memory: Neuroimaging memory and imagination with functional MRI

Modelling and visualisation of calcium waves in parotid acinar cells

Modelling and visualisation of calcium waves in parotid acinar cells

Mapping donor contributions in the Pacific

Mapping donor contributions in the Pacific

Visualising humpback whale migration

Visualising humpback whale migration

Visualising the 2010 and 2011  Canterbury earthquakes

Visualising the 2010 and 2011 Canterbury earthquakes

Data management planning for MOA*

Data management planning for MOA*

Research data publishing  and preservation at COMPASS

Research data publishing and preservation at COMPASS

Centre for eResearch machine learning service

Centre for eResearch machine learning service

Building a discrete global  grid gazetteer service

Building a discrete global grid gazetteer service

The new Wanhal catalogue

The new Wanhal catalogue

Passive acoustic modelling

Passive acoustic modelling

Using GPUs to expand our understanding of the Solar System

Using GPUs to expand our understanding of the Solar System

Shedding new light on dark matter

Shedding new light on dark matter

Aerodynamics modelling paves the way for improved yacht designs

Aerodynamics modelling paves the way for improved yacht designs

Modernising models to help diagnose or treat disease and injury

Modernising models to help diagnose or treat disease and injury

Wandering around the molecular landscape: embracing virtual reality as a research showcasing outreach and teaching tool

Wandering around the molecular landscape: embracing virtual reality as a research showcasing outreach and teaching tool

ALTER: Between human and nonhuman – a VR art exhibition

ALTER: Between human and nonhuman – a VR art exhibition

Disposition of Microsoft HoloLenses for a Pop-Up Reality Shop to demonstrate the progress of a research project

Disposition of Microsoft HoloLenses for a Pop-Up Reality Shop to demonstrate the progress of a research project

Improving diagnosis for schistosomiasis by using the ‘metabolic footprint’ of urine samples from an animal model of Schistosoma infection to identify possible biomarkers

Improving diagnosis for schistosomiasis by using the ‘metabolic footprint’ of urine samples from an animal model of Schistosoma infection to identify possible biomarkers

Making stroke recovery prediction tools freely available

Making stroke recovery prediction tools freely available

MFT-ICR mass spectrometry data management and analysis workflow

MFT-ICR mass spectrometry data management and analysis workflow

Taking a ‘Big Data’ approach to find new clinical-omic associations in cancer

Taking a ‘Big Data’ approach to find new clinical-omic associations in cancer

Growing Up in New Zealand

Growing Up in New Zealand

Improving arrival time predictions for vehicles in a public transport network

Improving arrival time predictions for vehicles in a public transport network

Distributed and cloud-based control at field-level for systems interacting with soft bodies

Distributed and cloud-based control at field-level for systems interacting with soft bodies

Mobile Click Fraud Attack (MCFA)

Mobile Click Fraud Attack (MCFA)

Skin-omics: exploring the volatile organic compounds on human skin

Skin-omics: exploring the volatile organic compounds on human skin

New analytics tools for workload planning for the 2018 New Zealand Census

New analytics tools for workload planning for the 2018 New Zealand Census

Visualising the New Zealand Index of Multiple Deprivation

Visualising the New Zealand Index of Multiple Deprivation