Janet Drew's Homepage
Welcome.
I joined the staff of the ICSTM Astrophysics Group in 1995 where I am
now Professor of Astrophysics.
I obtained my first degree in Physics from the University of
Durham (1976), and my
Ph.D. in Astrophysics from University College London (1980). Since obtaining
these qualifications, I have worked at UCL, IoA Cambridge, JILA in Boulder
Colorado, and was a lecturer for 8 years in Oxford up until 1995.
Strangely enough, I was the first woman to be appointed to a University
Lectureship in Oxford Physics (in 1986), and also the first female Professor
in the Physics Department here at Imperial (in 1999 - happily there are now
more of us).
I have two children: Sylvie born in 1988 and Duncan born in 1995.
My research interests are in stellar astrophysics. A particularly strong
theme in my work in the past has been theoretical and observational studies of
mass loss. Presently much of my work arises from the co-ordinating role I
have in an international collaboration surveying the Milky Way,
comprehensively, in the Hα line (see below). This project has the aim
of re-invigorating a wide range of Galactic/stellar astrophysics research
themes that currently suffer for want of good demographics.
office: Blackett 1010
email: j.drew@ic.ac.uk
office phone: 44-(0)207-594-7553
Present research activities:-
Understanding accretion disk winds
This is a long-standing interest, first sparked in the
1980s by the realisation that disk winds are a common phenomenon in
the universe -- they turn up in quasars and active galactic nuclei,
in a wide range of interacting binaries and in the pre main sequence
evolution of stars. Interacting binaries are good places to study
disk winds because the binarity provides clues that are usually
absent in the other settings (for example, if a binary is known to
be eclipsing, we know that the plane of the binary and hence of the
disk is almost perpendicular to the plane of the sky). The white
dwarf binaries known as cataclysmic variables have proved to be
excellent labs for the study of disk winds. Yet for all we know about
them, it is clear that the physics responsible for driving their
disk winds is still essentially unknown -- there are problems both
with radiation-driving and with magneto-hydrodynamic mechanisms.
A further intriguing mystery is why the evidence for jets, so commonly
associated with accretion disks in other settings, is so-far
non-existent. Work at ultraviolet wavelengths, using HST and FUSE,
continues, as does numerical work on the ionization and thermal
equilibrium of such flows.
Exploring young hot stars
The more massive a star is the rarer it is and the hotter
it is. Because of this, studies of young, cool low-mass stars are much more
advanced than studies of young, hot higher mass stars. At the same time
it is recognised that the massive star population in any given galaxy
has a big role to play in shaping that galaxy's evolution, through input
both of radiation and enriched matter. Accordingly all aspects of
massive star evolution, including how and why they form, are recognised as
astrophysically significant problems. I and people who work with me are
interested in exploring the differences between high- and low mass star
formation. To this end we continue to pursue a programme of study of
young intermediate mass stars (the Herbig Ae/Be stars), using
spectropolarimetric and other observational techniques. Our aim is to
uncover any dependences of the accretion/outflow geometries of these
young stars upon stellar mass.
This is a false-colour image, combining 3 bandpasses, derived from
IPHAS field 0003o (see below). At the centre of the image the dark
protrusion, silhouetted against nebular Hα emission is LDN 1270. This
is an extension to a larger dark cloud region to the right (west) in this
image. The bright nebulosity has been ionized by early type stars in the
cluster Be 29, off-image to the north. The bright double star at the top
of the dark region includes V463 Cep, a little-studied probable Herbig Be
star associated with it.
Surveying the plane of the Milky Way for Hα emitting stars
This ambitious venture began in 2002. It started with exploitation of the
AAO/UK Schmidt Hα photographic survey of the southern Galactic plane:
this was comprehensive in scope, combining complete coverage of a 20-degree
wide latitude band with high sensitivity and high spatial resolution (down to
about 1 arcsec). In collaboration with Australian astronomers and fellow
UK astronomers we have embarked on a follow-up spectroscopic survey aimed at
identifying and classifying Hα emission line point sources, picked up in
the imaging, across the entire southern Galactic plane down to a limiting red
magnitude of about 19.5. By going 6-7 magnitudes deeper than the last
generation of Hα surveys, this has the potential to increase the number
of known Hα point sources (either stars or compact nebulae) in the
Galaxy by a factor of 10 or more. Encouraged by early experiences in this
venture, I am also leading, IPHAS, a UK/Spain/Netherlands collaboration that
has begun a CCD/photometric survey of the northern Galactic plane, using the
Wide Field Camera mounted on the Isaac Newton Telescope in La Palma. First
observations were made in the north between August and December 2003.
Spectroscopic follow-up of this is just getting started. More details can be
found in the
Hα survey research pages on these programmes.
The value to astronomy of this survey of the plane of the Milky Way is
that Hα emission is typically a characteristic of most of the stellar
and binary evolutionary phases we understand not at all or hazily -- mainly
because so few are already known. This project stands to have a big impact
on studies of e.g. young and evolved high mass stars, young compact planetary
nebulae, and late-stage interacting binaries leading to supernovae. This will
occupy me for a few years to come and offers the potential for a whole raft of
new discoveries and smaller-scale projects. In the south, we have already
discovered (among our first few spectroscopic fields) a new massive WO star:
it is only the fourth known example of this extreme type of star in the Milky
Way, and its mass loss breaks the current terminal stellar wind speed record.
Weird science.....
At any one time, I usually have a favourite object.
Currently this is QU Car, a woefully neglected nova-like variable (a type
of interacting binary made up of an accreting white dwarf and a non-degenerate
mass-losing companion star). It was first picked out and named
over 30 years ago and, despite being as bright as 11th magnitude, was not
seriously studied again until we became interested in it. Our interest began
when we included it, as a bright nova-like variable, in an HST
ultraviolet spectroscopy programme undertaken a few years back.
Now that we have extremely high quality UV and optical spectra in hand we can
see that it is a strange beast: it looks to be very luminous (perhaps
as luminous as "supersoft" sources that are thought of as future
thermonuclear supernovae) and in possession of a carbon-rich companion
star. In this second respect, it is the first of its kind -- and, what
is more, no-one has predicted that such a binary has any right to exist.
MNRAS
I am a member of the Board of Editors handling the
peer review for `Monthly Notices of the Royal Astronomical Society'.
Last modification date: 30 March 2004
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