PhD Level

Armagh Observatory is known world-over as a leader in the field of astronomical research; we welcome PhD Candidates every year. Note: Applications for 2019 intake have closed.

Tracing biosignatures on planet Earth with high-resolution infrared spectropolarimetry

Supervisor: Stefano Bagnulo
Polarization spectra of planet Earth contain a rich imprint of its atmosphere and surface properties, including biosignatures. They are an important benchmark to constrain potential biosignatures of Earthlike planets scrutinized by future giant telescopes.

Today, biosignatures of planet Earth can be observed through Earthshine with ground-based astronomical facilities. This PhD project will encompass observations, analysis and modelling of polarization spectra of Earthshine in the near-infrared spectral bandpass from 1 - 2 𝜇m, to be obtained with CRIRES+ at the VLT and its novel high-resolution spectro-polarimetric capability.

With the help of detailed radiative transfer models of Earth, characteristic signatures of planet Earth will be extracted, and their sensitivity and specificity will be compared with the optical waveband, considering all instrumental and atmospheric parameters.

The results of this project will represent an important milestone in a trade-off analysis for the most suitable techniques and strategies to be used for the detection of biosignatures on exoplanets in the future.
The student will be part of an international collaboration including S. Bagnulo (AOP), C. Emde (LMU, Munich) and M. Sterzik (ESO, Garching).

For further information contact stefano.bagnulo@armagh.ac.uk

nasaglobe

Physical studies of asteroids with photometric and polarimetric techniques

Supervisor: Stefano Bagnulo
We are carrying out an intensive observing campaign to acquire new photometric and polarimetric data for various objects of the solar system, from comets to asteroids, to giant planets. Observations will be obtained from major facilities such as the VLT and the WHT, as well as two small to mid-size facilities: the observing station of Calern (a facility of the Observatory of Nice, France) and the Rozhen Observatory in Bulgaria.

veSTA

We are seeking a PhD student to join an international collaboration, involving researchers from Italy, France, Bulgaria (for the observations) and Finland (for the theoretical modelling). After a training period requiring a stay in Calern and in Rozhen, the student will take care of a large part of the observations and of data reduction, and will learn the basic principle of data modelling, with particular emphasis on the derivation of some important physical properties of the asteroids. This project will require observational activities partly on site, but mostly in remote mode, for typically a few weeks per year.

For further information contact stefano.bagnulo@armagh.ac.uk

Bursts of pink and red, dark lanes of mottled cosmic dust, and a bright scattering of stars — this NASA/ESA Hubble Space Telescope image shows part of a messy barred spiral galaxy known as NGC 428. It lies approximately 48 million light-years away from Earth in the constellation of Cetus (The Sea Monster). Although a spiral shape is still just about visible in this close-up shot, overall NGC 428’s spiral structure appears to be quite distorted and warped, thought to be a result of a collision between two galaxies. There also appears to be a substantial amount of star formation occurring within NGC 428 — another telltale sign of a merger. When galaxies collide their clouds of gas can merge, creating intense shocks and hot pockets of gas and often triggering new waves of star formation. NGC 428 was discovered by William Herschel in December 1786. More recently a type Ia supernova designated SN2013ct was discovered within the galaxy by Stuart Parker of the BOSS (Backyard Observatory Supernova Search) project in Australia and New Zealand, although it is unfortunately not visible in this image. This image was captured by Hubble’s Advanced Camera for Surveys (ACS) and Wide Field and Planetary Camera 2 (WFPC2). A version of this image was entered into the Hubble’s Hidden Treasures Image Processing competition by contestants Nick Rose and the Flickr user penninecloud. Links:   Nick Rose’s image on Flickr  Penninecloud’s image on Flickr

Exploring cosmic dust with Monte Carlo techniques

Supervisor: Stefano Bagnulo
A PhD project is available for a collaborative project to study the interstellar medium (ISM) under the joint supervision of Dr Stefano Bagnulo (Armagh Observatory & Planetarium) and Ralf Siebenmorgen (ESO Garching).
During their travel through the cosmos from stars to us, photons are scattered, polarised, absorbed, reemitted by dust particles. Dust surrounds various object types such as comets, young stellar objects, proto-planetary or debris disks, supernovae, and more so, extra-galactic objects, starburst galaxies, active galactic nuclei. Dust is also an important component of the interstellar and extra-galactic medium, the full characterisation of which is of crucial importance to understand the chemical history of the universe and various fundamental astrophysical processes.

Recent advances in computer technology enables the use of efficient Monte Carlo techniques to study the transport of radiation in arbitrary three-dimensional geometry for polarised or unpolarised light through a dusty medium. The goal of this PhD project is to study and explore the physics of the dust applying such MC treatments that shall be compared to existing archival and new observations of the ISM obtained with various instruments.
It is hoped that during the course of their PhD, the candidate will spend up to one year at the ESO Headquarters in Garching (Germany) to closely work with Dr Ralf Siebenmorgen.
This is a timely project to support understanding of new data obtained with our modern instrumentation that are available at the VLT, ALMA, and SOFIA, Planck, and to simulate new science case for future instrumentation projects such as METIS of ESO's Extremely Large Telescope (ELT).

For further information contact stefano.bagnulo@armagh.ac.uk

The co-orbital resonance as a tool to undestand the physical evolution of asteroids

Supervisor: Tolis Christou Asteroids - the scaffolding left over from the formation of the planets - continue to evolve to this day by the action of non-gravitational forces: the so-called Yarkovsky and YORP effects. In this way, Yarkovsky facilitates the continuous, ongoing delivery of meteorites and asteroids to the Earth through dynamical `escape hatches' while the YORP effect changes asteroid shapes and spins and creates binary asteroids and `families' in the Main Belt and elsewhere.
For near-Earth objects, non-gravitational effects are generally difficult to study, because close encounters with planets cause rapid dispersion of the orbits and wipe out the effects of slower population modification by Yarkovsky and YORP. But if the asteroid orbits are confined by dynamical resonances, close encounters are mitigated or eliminated entirely and the effects of the slower-acting non-gravitational forces may be studied in relative isolation.

ceres-pia17830

As a case in point, recent work by our group and others identified a family of kilometer sized or smaller Trojans of Mars and found that it has slowly been evolving for the past billion years or so, with new Trojans being created by YOPR fission and ultimately escaping through the Yarkovsky effect.
The findings have important implications for Trojans and other so-called "co-orbital" asteroids of our own planet. For instance, asteroids near 1 au that break up due to YORP spin-up could form recognisable orbital clusters or streams of small debris that create meteor showers in the atmosphere. Further afield, any debris co-orbital with close-in exoplanets would evolve quite significantly and rapidly due to the Yarkovsky effect, giving rise to features that may betray the presence of the planetary body.

In this project we want to quantify asteroid evolution under non-gravitational forces, applying our findings to different settings. The successful applicant is expected to have some experience with numerical orbit integrations. A general familiarity with techniques of dynamical astronomy will be seen as an advantage.

For further information contact Apostolos.Christou@Armagh.ac.uk

The fine-scale structure of chromospheric jets and their formation process

Supervisor: Gerry Doyle
Armagh Observatory & Planetarium are partners in the Daniel K. Inouye Solar Telescope (DKIST) which is scheduled to see first light in late spring 2019. With the availability of higher spatio-temporal resolution observations from current instruments in space (e.g., IRIS, SDO/AIA etc) and the ground (e.g., SST/CRISP, ROSA etc), the solar chromosphere has shown an ubiquitous presence of jet-like plasma ejecta at diverse spatio-temporal scales (e.g., spicules, network jets, anemone jets, swirls, penumbral jets, pseudo-shocks etc).
In this work, we aim to observe the fine structured and highly dynamic chromosphere in the quiet-Sun (QS), coronal hole (CH), and active regions (AR), where a variety of plasma ejecta are eventually evident. These features contribute in transporting energy and mass in their respective overlying atmospheres in entirely different ways. For example, the coronal hole will most likely be subjected to the much longer spicules in a dominant way, while the quiet-Sun may be subjected with a mixture of spicules, network jets, swirls etc.

On the other hand, the sunspot groups (active regions) may possess very energetic ejecta like penumbral jets, plasma flows, pseudo-shocks, etc. Therefore, the morphological, physical (drivers), kinematical evolution of such various jets in the diverse ambient magneto-plasma atmosphere (QS, AR, CH) will provide unprecedented information and distinction on how they evolve and their role in energy and mass transport. Such data will also enable us to understand the evaluation of the role of magnetic reconnection and/or waves in their formation, as well as, their contribution towards coronal heating and formation of the nascent solar wind.
This project proposes to use DKIST in various observing sequences, e.g. combination of DL- NIRSP, VTF and VBI; a combination of DL-NIRSP, ViSP, and VBI for the targets of AR (both near the Sun center and limb), QS (on-disk), and CH (at higher latitudes). The high cadence temporal image data (VBI & VTF); polarimetric scans (DL-NIRSP), and intensity-mode spectral profiles (ViSP) will be obtained in various jet enriched regions. Their magnetic field information, velocity information, and emissions will be constrained, which will provide details on their triggering and evolution. Moreover, various atmospheric heights and/or plasma temperatures will be taken into account in the analyses of jets, and thereby their role in various layers of the Sun's atmosphere.

For further information contact gerry.doyle@armagh.ac.uk

664504main_chromosphere-orig_full

Heavy Metal Stars, Hyper-velocities and Explosions

Supervisor: Simon Jeffery
Binary star interactions disrupt the direct line between star birth and death as a white dwarf or supernova. The most exotic stars in the Universe are products of such interactions, including various classes of star with surfaces deficient or devoid of hydrogen. Using the Southern Africa Large Telescope (SALT), the Armagh Observatory and Planetarium is surveying hydrogen-deficient stars to identify new exotics, including the very rare heavy-metal sub-dwarfs. These have excessive surface abundances of lead, zirconium and other elements, extraordinarily high-energy orbits, and other unexplained properties. Their origin is unknown; one proposal involves ejection from a supernova explosion, but the picture is complicated by atomic diffusion in the stellar photosphere.

The NASA/ESA Hubble Space Telescope has captured a crowd of stars that looks rather like a stadium darkened before a show, lit only by the flashbulbs of the audience’s cameras. Yet the many stars of this object, known as Messier 107, are not a fleeting phenomenon, at least by human reckoning of time — these ancient stars have gleamed for many billions of years. Messier 107 is one of more than 150 globular star clusters found around the disc of the Milky Way galaxy. These spherical collections each contain hundreds of thousands of extremely old stars and are among the oldest objects in the Milky Way. The origin of globular clusters and their impact on galactic evolution remains somewhat unclear, so astronomers continue to study them through pictures such as this one obtained by Hubble. As globular clusters go, Messier 107 is not particularly dense. Visually comparing its appearance to other globular clusters, such as Messier 53 or Messier 54 reveals that the stars within Messier 107 are not packed as tightly, thereby making its members more distinct like individual fans in a stadium's stands. Messier 107 can be found in the constellation of Ophiuchus (The Serpent Bearer) and is located about 20 000 light-years from the Solar System. French astronomer Pierre Méchain first noted the object in 1782, and British astronomer William Herschel documented it independently a year later. A Canadian astronomer, Helen Sawyer Hogg, added Messier 107 to Charles Messier's famous astronomical catalogue in 1947. This picture was obtained with the Wide Field Camera of Hubble’s Advanced Camera for Surveys. The field of view is approximately 3.4 by 3.4 arcminutes.

This PhD programme will start by classifying spectra of hydrogen-deficient stars from the SALT survey. The student will make follow-up observations using small and large telescopes, where evidence of chemical abnormalities, pulsations and orbital motion will be sought. Results will be combined holistically with data from the GAIA, TESS, Kepler and Galex space missions. The initial focus will be on the population of heavy-metal sub-dwarfs. The student will be encouraged to develop and apply techniques for studying chemical structure in the atmospheres of theses stars, and to decode evidence of their previous history.
Links:

Hydrogen-Deficient Stars http://www.armaghplanet.com/blog/hydrogen-deficient-stars-2018-armagh-observatory-andplanetarium.html

Heavy-Metal Subdwarfs https://academic.oup.com/astrogeo/article/56/2/2.32/178659

For further information contact simon.jeffery@armagh.ac.uk

goto-dome-night

The Gravitational-wave Optical Transient Observer (GOTO)

Supervisor: Gavin Ramsay
Armagh Observatory is a full partner of the Gravitational-wave Optical Transient Observer (GOTO http://goto-observatory.org) project which aims to detect the optical counterpart of gravitational wave events detected by the Advanced Ligo and Virgo detectors. It is sited on the island of La Palma in the Canaries, and Phase I operations are proceeding. The recent detection of the optical counterpart of a merging neutron star binary in Sept 2017 showed that these counterparts are bright enough to be detected by GOTO. However, this outburst was located too far to the south to be detected by GOTO.

Our strategy involves mapping the observable sky on a regular basis. The data is providing a huge resource to study variable stars; transients such as gamma-ray bursts and supernova; flare stars; asteroids and comets and time domain astrophysics in general. A PhD project is available to work on data obtained using GOTO and would suit someone interested in observational astronomy and ideally someone with experience of analysing astronomical data. It is expected there would opportunities for travelling to La Palma and to use using international telescopes to make detailed observations of objects discovered in these surveys.

For further information contact gavin.ramsay@armagh.ac.uk

The first stars in the Universe

Supervisor: Dr Jorick Vink
Some few hundred million years after the Big Bang the Universe lit-up by the formation of the First Stars, which are thought to have been very massive owing to their pristine chemistry. Despite their key role in setting the stage for the subsequent Cosmic chemistry, we know surprisingly little about the evolution & fate of the first few stellar generations.

This new NASA/ESA Hubble Space Telescope image shows a variety of intriguing cosmic phenomena. Surrounded by bright stars, towards the upper middle of the frame we see a small young stellar object (YSO) known as SSTC2D J033038.2+303212. Located in the constellation of Perseus, this star is in the early stages of its life and is still forming into a fully grown star. In this view from Hubble’s Advanced Camera for Surveys (ACS) it appears to have a murky chimney of material emanating outwards and downwards, framed by bright bursts of gas flowing from the star itself. This fledgling star is actually surrounded by a bright disc of material swirling around it as it forms — a disc that we see edge-on from our perspective. However, this small bright speck is dwarfed by its cosmic neighbour towards the bottom of the frame, a clump of bright, wispy gas swirling around as it appears to spew dark material out into space. The bright cloud is a reflection nebula known as [B77] 63, a cloud of interstellar gas that is reflecting light from the stars embedded within it. There are actually a number of bright stars within [B77] 63, most notably the emission-line star LkHA 326, and its very near neighbour LZK 18. These stars are lighting up the surrounding gas and sculpting it into the wispy shape seen in this image. However, the most dramatic part of the image seems to be a dark stream of smoke piling outwards from [B77] 63 and its stars — a dark nebula called Dobashi 4173. Dark nebulae are incredibly dense clouds of pitch-dark material that obscure the patches of sky behind them, seemingly creating great rips and eerily empty chunks of sky. The stars speckled on top of this extreme blackness actually lie between us and Dobashi 4173. Link  Hubble’s Advanced Camera for Surveys

The goal of this theoretical PhD project is to predict the amount of mass the first stars loose through stellar winds. These winds will have enriched the Early Universe even before the first supernovae, and they determine not only the evolution & fate of these First Stars, but also their appearance. Their appearance will be crucial for observations of the first galaxies by the James Webb Space Telescope and the E-ELT.

For further information contact jorick.vink@armagh.ac.uk

planetarium-slide-1
Contibute to the growing wealth of astronomical research

PhD Application Information

Applications are invited for a 3 year postgraduate research studentship(s) tenable at Armagh
Observatory & Planetarium from Sept/Oct 2020.
Armagh Observatory, located in Northern Ireland, UK, is an astrophysical research institute
founded in 1789. It has 8 staff astronomers, 2 post-doctoral fellows, a dozen PhD students
and several visiting astronomers. Research interests include Solar Physics, Solar-System
Science, Stellar, Galactic and Extra-galactic Astrophysics.
Candidates must have, or expect to obtain, at least an upper second class honours degree or
equivalent, in an appropriate discipline (e.g. Physics, Mathematics, Astronomy or
Astrophysics). Successful candidates will enroll at an appropriate university and carry out a
research programme at the Armagh Observatory & Planetarium. Applications are encouraged
from candidates of any nationality. The successful applicant(s) would receive a grant based
on the United Kingdom Science and Technology Facilities Council rate (2019/20: £14,777 per
annum). In addition, we would fully fund the university fees.
Prospective candidates should fill in the application form available from this web site and
ensure that their references are received by the administrator before the deadline. First
selection will take place as soon as possible after 2020 February 25th with subsequent
selections thereafter until all positions have been filled.
The application form, CV and other supporting documents should be sent to the administrator
(hr@armagh.ac.uk). If potential applicants have questions they can be sent to the
administrator or the potential supervisor for the project which are listed on our web site.