Newton STFC-NARIT - EXOhSPEC (Exoplanet high-resolution Spectrograph)

Lead Research Organisation: University of Hertfordshire
Department Name: School of Physics, Astronomy and Maths

Abstract

The project is to build from catalogue components a new kind of high-resolution spectrograph. The concept relies on separating the complexity introduced by Earth from the requirements of the spectrometer unit itself. This separation
enables a massive reduction in size and complexity on the spectrometer side and it is the natural complement to Adaptive Optics technologies being developed elsewhere. The concepts demonstrated here might be used to save tens of millions of pounds in instrumentation costs on the coming generation of extremely large telescopes but also be reproducible by University, public and amateur observatories and offer a competitive alternative to the purchase of large inefficient Fourier transform spectrometers in the wider marketplace. The key developments that we wish to demonstrate are, (1) a compact inexpensive design that can achieve the same performance as existing instruments in terms of wavelength coverage and spectral resolution and (2) bespoke active metrology/actuation of the system to achieve -or even surpass- the best wavelength calibration stability at a fraction of construction and operation costs and to produce a facility instrument. While the prototyping for this instrument is at the University of Hertfordshire, the facility instrument will be produced in Thailand but with the insight gained from operating a prototype version on the new 0.7m. The Thai government has made a large investment in the National Astronomical Research Institute of Thailand and so they have the new laboratories in which to build the instrument as well as immediate access to a new 0.7m. Current high-resolution spectrographs are large, expensive and difficult to maintain and are reserved to an elite of a handful universities and groups around the globe. Moreover, because these instruments are so expensive, technology cycles and designs have evolved very little and do not take advantage of the great quality improvement and reduced costs of new materials and mass produced optics. In a sense, the technological leap we want to embrace is like the one between the first digital cameras to the current smartphone technology. The economic development and welfare of a country relies on key infrastructure and the capabilities of the workforce. In the field of physics and in particular astrophysics, the ability to design and make instruments and to measure and interpret the properties of the transitions in other planets, stars and galaxies is a key cornerstone to understand the properties of the Universe. High-resolution spectroscopy has for decades being a primary tool of astrophysics and a driving force in enabling new fundamental astrophysics. From the discovery of planets around nearby stars to the direct measurement of the size of the Universe. Worldwide, the most oversubscribed instruments on telescopes have long been the high-resolution spectrographs. Although Thailand has a large telescope and a number of smaller ones it does not have a high resolution spectrograph. The proposal is aimed at using Overseas Development Aid funding to develop Thai infrastructure and capabilities while at the same time opening up a new collaboration which should have long-term benefit to the UK scientists and engineers.

Planned Impact

The partners have established yet different strengths, and the outcome of this project is envisaged to be one that widens the impact of each partner but strengthens collaborations. Each has a strong track record of engagement with industry, other disciplines, the public and schools. Much of this capitalizes on infrastructure provided at the different institutions, which coordinates local programmes in training, enterprise and outreach. Students and research staff will be encouraged to participate in these activities, with emphasis on personal development but also as part of an appropriate engagement with non-scientists.

Knowledge Exchange
This project will develop new practice in high-resolution spectrographs. Such an instrument is common with many areas outside astronomy such as medicine, bio-sciences, telecommunications, remote sensing and earth observation. Such developments may fall across a huge variety of commercial interests and all the UK research councils. The team would consider the licensing and commercialisation of IP, and we might seek out forums that would provide opportunities for researchers to meet with corporate and other non-astrophysics-based research sectors. We have good access to such events, particularly through the South East Physics Network. We have established an excellent working relationship with NARIT who are very actively investing and developing all aspects of Science and Technology in Northern Thailand.

Career Development
Researcher development is an important focus of the institutions training programmes. This project is highly collaborative and a fast moving area and suitable liaison with industry will be for short-term delivery of specifications but longer-term development of new capabilities. We have active collaborations at all levels with groups very interested in this work, in particular, Sydney (Bland-Hawthorn), Penn State (Larry Ramsey), Arcetri (Tino Olivia), Potsdam (Roger Haynes) and Gottingen (Ansgar Reiners) and are likely to be in communication with some of these groups during the project (exchanges of RAs and PhD students are possible though not specifically envisaged).

Public Engagement and Outreach
The project team has a remit to develop outreach activities related to astronomical research/ technology. Our project will fall nicely into these categories, as it combines novel optical devices with a potential for discussing exoplanets - one of the most popular areas of public engagement. We regularly host groups of teachers and students for visits to our labs, and our spectrograph - and its science applications - would no doubt represent a fascinating item to discuss with them. NARIT is particularly organised with regard to public engagement, for example, they regular allow eyepiece observing through their 2.4m telescope. We look forward to learning from them. Exoplanets and new instrumentation is a particularly good niche for communication through local, national and international media appearances and we are fully aware of the intense interest having recently announced Proxima b. Outreach and public engagement are core elements of our activities and we would expect that all researchers would be involved in open days and evenings, school visits and talks to local astronomical societies. Our instrument (likely the prototype) together with input from Bath - fibres, Durham - adaptive optics, Heriot Watt - laser comb would make for a particularly exciting Royal Society exhibition and we could consider a proposal for such an exhibition. At NARIT their new 0.7m has been designed with EXOPhSPEC and its outreach potential as a tourist attraction along with their whole new campus.

Publications

10 25 50
 
Description Exoplanet Guide - https://www.herts.ac.uk/h2h
Geographic Reach Multiple continents/international 
Policy Influence Type Influenced training of practitioners or researchers
 
Description Prince of Songkla University 
Organisation Prince of Songkla University Thailand
Country Thailand 
Sector Academic/University 
PI Contribution A University of Hertfordshire PhD student is making laboratory measurements of a range of tapered fibres.
Collaborator Contribution Chalongrat Daengngam and his research group are experts in the use of COMSOL software and supporting a University of Hertfordshire PhD student to focus their focus based on their super-computer taper fibre simulations.
Impact This collaboration is multi-disciplinary
Start Year 2019
 
Title Exoplanet transit prediction tool 
Description Transit Follow Up Tool Website code in PHP to predict transit events with the ability to include off transit time before and after. Also the ability to predict the uncertainty of the photometry on CCD cameras. 
Type Of Technology Webtool/Application 
Year Produced 2018 
Impact Enhanced ability to measure exoplanet transits from sites with poor conditions. 
URL http://observatory.herts.ac.uk/exotransitpredict/
 
Title PEXO 
Description PEXO, a package for Precise EXOplanetology to facilitate the efficient modeling of timing, astrometry, and radial velocity data, which will benefit not only exoplanet science but also various astrophysical studies in general. PEXO is general enough to account for binary motion and stellar reflex motions induced by planetary companions and is precise enough to treat various relativistic effects both in the solar system and in the target system. We also model the post-Newtonian barycentric motion for future tests of general relativity in extrasolar systems. We benchmark PEXO with the pulsar timing package TEMPO2 and find that PEXO produces numerically similar results with timing precision of about 1 ns, space-based astrometry to a precision of 1 µas, and radial velocity of 1 µm s-1 and improves on TEMPO2 for decade-long timing data of nearby targets, due to its consideration of third-order terms of Roemer delay. PEXO is able to avoid the bias introduced by decoupling the target system and the solar system and to account for the atmospheric effects that set a practical limit for ground-based radial velocities close to 1 cm s-1. 
Type Of Technology Webtool/Application 
Year Produced 2019 
Open Source License? Yes  
Impact Aside from moving exoplanet software on, this software is potentially critical to pulsar timing data as well as finding gravitational waves. In particular, it reveals some bugs in pulsar timing software some expressed in the PEXO paper and another one below. The pulsar timing model actually depends on other factors such as ephemerides and GPS location of the telescopes. It is more sensitive to models than atomic clocks. The pulsar timing codeTEMPO2 uses the light arrival time at the target barycenter to calculate the ephemerides of the target star. However, it should be the light emission proper time due to the Roemer delay in the target system (as correctly pointed out in eqs. 61, 64, and 71 of Edwards et al. 2006), similar to the solar system TDB. This potential bug is more significant than the Shapiro delay one. This bug is evident from the following code in DDGRmodel.C t0 = psr[p].param[param_t0].val[0]; ct = psr[p].obsn[ipos].bbat; tt0 = (ct-t0)*SECDAY; ... x = psr[p].param[param_a1].val[0]+xdot*tt0; ecc = psr[p].param[param_ecc].val[0]+edot*tt0; 
URL https://mybinder.org/v2/gh/phillippro/pexo/binder
 
Title flexible data reduction tool to extract echelle spectra, developed for the EXOhSPEC spectrograph 
Description Software takes a fits image containing a cross-dispersed spectrum and extracts the spectral orders regardless of separation and curvature, applies wavelength correction and other standard data reduction procedures. 
Type Of Technology Software 
Year Produced 2018 
Open Source License? Yes  
Impact This can be used for the extraction of a spectrum from any cross-dispersed spectrograph with a bifurcated fibre. 
URL https://github.com/ronnyerrmann/exohspec/