Hertfordshire Astronomy

The Centre for Astrophysics Research carries out observational programmes spanning the wavelength range from X-ray up to the radio - supporting this by extensive computer modelling, theoretical studies and instrument development. Our research ranges from theoretical modelling of the highest energy process in the Universe through to inventing our own instruments to detect planets outside our Solar System. In between these extremes, we carry out the largest multi-wavelength surveys conducted to date to understand the properties of stars, galaxies and their evolution. Our research makes use of observations from all of the main European and international astronomical observatories, including ground-based observatories at optical, radio and submillimetre wavelengths, and space observatories at wavelengths ranging from the far infrared to gamma rays. We also use computer simulations to obtain a better understanding of the physical processes detected in our observations. Below is a brief description of our research in each of these areas.

We perform searches of nearby stars to discover planets. We especially target low mass M stars since they are the dominant type of star in the Universe and have not yet been searched. We focus on detection through Doppler wobble and by looking for planets periodically eclipsing their parent star. During the period of the grant we expect to make the first detections of Earth-mass planets in the habitable zones of the closest stars. We also discover, follow-up and model the properties of the coolest brown dwarfs whose temperatures overlap with those of planets. These studies aim to clarify the population of brown dwarfs and to establish how their modes of formation fit in with those of their brethren of different masses, ie. heavier (stars) or lighter (planets).

The Milky Way is our home galaxy. The material in the form of gas is the raw material for the formation of stars and planetary systems. At the end of stellar lives some of this material remains locked up in stellar remnants but much of it is returned in late superwind phases and supernova explosions. This cycle is responsible for the chemical enrichment of the gaseous medium and is important for its dynamics, because of the thermal and mechanical energy injected into the gas. By using large area mainly imaging surveys, our research looks at this gas in the Milky Way and its satellites. Our surveys of the Milky Way will span the optical to sub-mm domains tracing extinction, molecular clouds, their dust properties and associated star formation. We thus study the relationship between star formation, dust and molecular cloud properties.

In the nearby Universe it is possible to appraise how stars form and evolve in different environments, from small dwarf galaxies to the very outer regions of galaxies like our own. Our research focuses on the gas content of galaxies, which provides the material for star formation, and links this to stellar populations and the locations of star formation in the full range of local galaxies. By understanding the processes that trigger star formation and its evolution in the nearby Universe, we can begin to apply this understanding to the very earliest galaxies and the formation of stars in the distant Universe.

A new generation of surveys is mapping out the most distant galaxies, and allows us to investigate what links the processes of star formation and the growth of supermassive black holes. We also use detailed X-ray and radio observations to measure the energy injected by jets ejected from supermassive black holes into distant galaxies and clusters of galaxies, affecting star formation and gas properties, and having a long-term role in their evolutionary history. Understanding the particle composition, magnetic field properties, dynamics and energetics of these relativistic jets is essential in order to get a complete picture of star formation and of galaxy evolution.

(a) INDUSTRY Pinfield (UH) leads ROPACS, an EU "Initial Training Network". Although EU funded, scientific input for the ITN bid was supported by STFC grants & STFC facilities are used extensively for associated observing programmes. The ITN trains 15 young researchers across 6 EU institutes & carries out R&D for "Rocky Planets Around Cool Stars". Astrium, is a partner in RoPACS, & through this RoPACS is exploring the potential for future ESA missions to study exoplanets (EXPs) as part of "Cosmic Vision 2015-2025". Astrium provide training for the young researchers, including raising awareness that their cognitive abilities are needed in an industrial context & helping them to understand how academia can be closely inter-twined with high technology manufacturing.
The RoPACS-Astrium team provided input on "technology readiness" issues to an ESA-commissioned report laying out an EXP roadmap (EPRAT), giving a welcome level of communication between industry & academia. A UH research student was directly involved in an industrially-led system definition study, feeding into a future mission science-led proposal (EXP Characterisation Observatory - ECHO). This yields many tangible commercial benefits, including a competitive advantage for any future missions & a strengthened national commitment if there is a strong UK science component. ESA has now selected ECHO for an initial Assessment Phase.
As part of the collaboration, we are exploring how science mission "spin-out" across industry can lead to wealth creation. Astrium has important influence on government, recently providing evidence to UKSA on "technology benefits from science missions" & "the impact of space science missions on engineering & the economy" to help make the case for science in the 2010 CSR. The Astrium report concluded that space science missions have a very strong impact on space engineering as they are always pushing technological & engineering limits which can then be used on commercial satellites.
(b) OTHER SCIENCE COMMUNITIES: ATMOSPHERIC PHYSICS - A PPARC grant enabled the construction of a highly-sensitive polarimeter (PlanetPol) to detect reflected light from EXPs. It has a polarization sensitivity of 1 ppm, by far the highest ever achieved for a polarimeter on a telescope. During one set of WHT observations, some stars were found to have polarizations an order of magnitude larger than previously observed. This coincided with a Saharan dust event over the island & it was concluded that the polarization was produced by dichroic absorption in the dust & that the dust was oriented vertically, not horizontally as expected from aerodynamic forces. Detailed calculations showed that the observed effect must result from the presence of electric fields, most likely generated by the dust itself. This has implications for atmospheric models (hence climate modelling) & for the accurate retrieval of data from ground and space observations. The behaviour of mineral aerosol is one of the least understood of atmospheric components.
(c) SCHOOL TEACHERS- The University Observatory, with optical & radio telescopes, is used extensively as a key part of the East of England Science Learning Centre (SLC) based on the same site, & CAR researchers frequently deliver parts of the PDP for school teachers. Our "Hydrogen to Humans" resource was a primary element in the National SLCs being awarded a £1 million grant by RCUK.
(d) THE PUBLIC - Six Open Evenings are held at the University Observatory each year attracting 400+ paying visitors/night, featuring hands-on interactive laboratory experiments, access to all telescopes, and talks by researchers. Most events are based around a CAR research theme. Feedback is very positive & many visitors attend sessions over several years. We attract many young people who are clearly enthused by the opportunity to look through telescopes, to talk to the many astronomers who support the events, & to take part in the many experiments.