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
Beichman C
(2006)
New Debris Disks around Nearby Main-Sequence Stars: Impact on the Direct Detection of Planets
in The Astrophysical Journal
Norton A
(2007)
New periodic variable stars coincident with ROSAT sources discovered using SuperWASP
in Astronomy & Astrophysics
Bentz M
(2007)
NGC 5548 in a Low-Luminosity State: Implications for the Broad-Line Region
in The Astrophysical Journal
Fynbo JP
(2006)
No supernovae associated with two long-duration gamma-ray bursts.
in Nature
Varnière P
(2006)
Observational Properties of Protoplanetary Disk Gaps
in The Astrophysical Journal
Keto E
(2006)
Observations on the Formation of Massive Stars by Accretion
in The Astrophysical Journal
Cassan A
(2006)
OGLE 2004-BLG-254: a K3 III Galactic bulge giant spatially resolved by a single microlens
in Astronomy & Astrophysics
Angus G
(2007)
On the Proof of Dark Matter, the Law of Gravity, and the Mass of Neutrinos
in The Astrophysical Journal
Knebe A
(2009)
ON THE SEPARATION BETWEEN BARYONIC AND DARK MATTER: EVIDENCE FOR PHANTOM DARK MATTER?
in The Astrophysical Journal
Wyatt M
(2007)
Origin of the metallicity dependence of exoplanet host stars in the protoplanetary disc mass distribution
in Monthly Notices of the Royal Astronomical Society
Dominik M
(2009)
Parameter degeneracies and (un)predictability of gravitational microlensing events
in Monthly Notices of the Royal Astronomical Society
Gu S
(2007)
Photometric follow-up observation of some SuperWASP transiting planet candidates
in Proceedings of the International Astronomical Union
Hong-Bo T
(2014)
Photometric Observation and Study of the Transiting Exoplanetary System HAT-P-8
in Chinese Astronomy and Astrophysics
Wang X
(2007)
Photometric observation of the transiting exoplanet WASP-1b
in Proceedings of the International Astronomical Union
Lanza A
(2009)
Photospheric activity and rotation of the planet-hosting star CoRoT-4a
in Astronomy & Astrophysics
Southworth J
(2009)
PHYSICAL PROPERTIES OF THE 0.94-DAY PERIOD TRANSITING PLANETARY SYSTEM WASP-18
in The Astrophysical Journal
Llinares C
(2009)
PHYSICS OF GALACTIC COLLIDERS: HIGH-SPEED SATELLITES IN ?CDM VERSUS MONDIAN COSMOLOGY
in The Astrophysical Journal
Rahvar S
(2009)
Planetary microlensing signals from the orbital motion of the source star around the common barycentre
in Monthly Notices of the Royal Astronomical Society
Rice W
(2006)
Planetesimal formation via fragmentation in sel-gravitating protoplanetary discs
in Monthly Notices of the Royal Astronomical Society: Letters
Lazorenko P
(2009)
Precision multi-epoch astrometry with VLT cameras FORS1/2
in Astronomy & Astrophysics
Greaves J
(2007)
Predicting the frequencies of diverse exo-planetary systems
in Monthly Notices of the Royal Astronomical Society: Letters
Calchi Novati S
(2007)
Probing MACHOs by observation of M 31 pixel lensing with the 1.5 m Loiano telescope
in Astronomy & Astrophysics
Dumusque X
(2017)
Radial-velocity fitting challenge II. First results of the analysis of the data set?
in Astronomy & Astrophysics
Smith A
(2008)
Radio cyclotron emission from extra-solar planets
in Proceedings of the International Astronomical Union
Jardine M
(2008)
Radio emission from exoplanets: the role of the stellar coronal density and magnetic field strength
in Astronomy & Astrophysics
Description | Not applicable this year |
Exploitation Route | Not applicable this year |
Sectors | Education |