Astrophysics at St.Andrews
Lead Research Organisation:
University of St Andrews
Department Name: Physics and Astronomy
Abstract
Our Galaxy contains many fossils of its formation history. Smaller galaxies that collided with the Milky Way long ago formed streams of stars that still linger as fossils of the Galaxy's formation, orbiting in the gravitational field of the Galaxy's primordial dark-matter halo. From 2011 the GAIA mission will map the positions and motions of these streams. We will develop new techniques to use data from GAIA to map the dark matter, and to test whether conventional theories of gravity work as expected at large distances. Clusters of new stars and planetary systems are constantly forming inside the dark clouds of gas and dust that delineate the Milky Way's spiral arms. In the biggest clusters, stars form that are up to 100 times as massive as the Sun. These massive stars burn so brightly that they are clearly visible in neighbouring galaxies. Many of them are binary stars. Our measurements of their mutual eclipses and spectra will reveal their sizes and temperatures, and hence the distances to the nearest galaxies. We do not yet understand how these massive stars form, or why so many of them are binaries. We will simulate how the most massive and hottest stars manage to form despite the tendency of their radiation fields to blow away the gas that feeds them. We also aim to find out how their winds, and the shock waves from the supernova explosions that eventually blow them apart, affect neighbouring gas clouds, perhaps triggering new bursts of star formation. The dark clouds where stars form contain needle-like dust grains that line up with the Galaxy's magnetic fields and polarize radiation passing through them. We will measure the polarization of infrared and mm-wave radiation coming from regions where cloud material is just beginning to form new stars, to discover what is happening to the magnetic field and to the grains themselves as the star condenses. Newly-born stars are surrounded by flat, rotating discs of gas and dust, which persist for two or three million years. As planets form in the disc material, some gas continues to feed the growing star, which at this stage possesses a strong magnetic field. We can now map these stars' magnetic fields using new instruments. We will use these maps to predict how the magnetic field acts to channel material into streams, and how the field structure regulates the flow rate on to the star and the star's spin. We will seek out rapidly rotating young stars near the Sun, in remnants of star clusters that formed up to 50 million years ago but fell apart. By this age the discs have gone, but an enigmatic fossil remnant of earlier processes lingers in their spin rates. Among otherwise identical stars in the same cluster, some spin much faster than others. We want to know if this difference in spin rate is a clue as to how many stars possess planetary systems, or if the difference originates in some peculiarity of the stars' magnetic fields. We will map the magnetic fields of the fast rotators and their more slowly-rotating siblings, to see if there is a difference in the rate at which hot gas flowing out along the field lines can carry away the star's spin. Finally, we will seek out planetary systems around nearby and distant stars. We are working with astronomers at several other institutions to monitor the brightnesses of hundreds of thousands of nearby stars, in order to pick out tiny dips in light caused by close-orbiting Jupiter-sized planets passing in front of their parent stars. We aim to discover dozens of such planets, and to measure their sizes, masses and temperatures. We will also search for planets further from their stars, by monitoring distant stars whose light is being temporarily magnified by the gravitational field of a foreground star. Distortions in the resulting light variation have already revealed Jupiter-mass planets around a couple of these foreground stars. We aim to find many more using a network of new robotic telescopes.
Organisations
Publications
Jeong J
(2015)
REANALYSES OF ANOMALOUS GRAVITATIONAL MICROLENSING EVENTS IN THE OGLE-III EARLY WARNING SYSTEM DATABASE WITH COMBINED DATA
in The Astrophysical Journal
Zhao H
(2006)
Refining the MOND Interpolating Function and TeVeS Lagrangian
in The Astrophysical Journal
Hood B
(2008)
Reflected light from 3D exoplanetary atmospheres and simulation of HD 209458b
in Monthly Notices of the Royal Astronomical Society
Tsapras Y
(2009)
RoboNet-II: Follow-up observations of microlensing events with a robotic network of telescopes
in Astronomische Nachrichten
Zhao H
(2006)
Roche lobe shapes for testing MOND-like modified gravities
in Astronomy & Astrophysics
Gregory S
(2006)
Rotationally modulated X-ray emission from T Tauri stars
in Monthly Notices of the Royal Astronomical Society
Smith A
(2009)
Secondary radio eclipse of the transiting planet HD 189733 b: an upper limit at 307-347 MHz
in Monthly Notices of the Royal Astronomical Society
Wang Y
(2008)
Self-consistent Models of Triaxial Galaxies in MOND Gravity
in The Astrophysical Journal
McIvor T
(2006)
Simulated X-ray cycles in rapidly rotating solar-like stars
in Monthly Notices of the Royal Astronomical Society
Dobbs C
(2008)
Simulations of spiral galaxies with an active potential: molecular cloud formation and gas dynamics
in Monthly Notices of the Royal Astronomical Society
Greaves J
(2006)
Space debris and planet detection
in Astronomy and Geophysics
Moutou C
(2007)
Spectropolarimetric observations of the transiting planetary system of the K dwarf HD 189733
in Astronomy & Astrophysics
Dobbs C
(2007)
Spiral shocks and the formation of molecular clouds in a two-phase medium
in Monthly Notices of the Royal Astronomical Society
Bonnell I
(2006)
Spiral shocks, triggering of star formation and the velocity dispersion in giant molecular clouds
in Monthly Notices of the Royal Astronomical Society
Lada C
(2006)
Spitzer Observations of IC 348: The Disk Population at 2-3 Million Years
in The Astronomical Journal
Blecic J
(2014)
SPITZER OBSERVATIONS OF THE THERMAL EMISSION FROM WASP-43b
in The Astrophysical Journal
Dobbs C
(2006)
Spurs and feathering in spiral galaxies
in Monthly Notices of the Royal Astronomical Society
Bonnell IA
(2008)
Star formation around supermassive black holes.
in Science (New York, N.Y.)
Bonnell I
(2006)
Star formation through gravitational collapse and competitive accretion
in Monthly Notices of the Royal Astronomical Society
Wyatt M
(2007)
Steady State Evolution of Debris Disks around A Stars
in The Astrophysical Journal
Barstow M
(2008)
Stellar and galactic environment survey (SAGE)
in Astrophysics and Space Science
Barstow M
(2008)
Stellar And Galactic Environment survey (SAGE)
in Experimental Astronomy
Davies M
(2006)
Stellar encounters involving massive stars in young clusters Stellar encounters involving massive stars
in Monthly Notices of the Royal Astronomical Society
Vidotto A
(2014)
Stellar magnetism: empirical trends with age and rotation
in Monthly Notices of the Royal Astronomical Society
Jardine M
(2008)
Stellar mass ejections
in Proceedings of the International Astronomical Union
Description | Not applicable this year |
Exploitation Route | Not applicable this year |
Sectors | Education |