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The Astronomy Department (UCT)

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Title: The Astronomy Department (UCT)


1
The Astronomy Department (UCT)
Renée C. Kraan-Korteweg, Head of Astronomy
  • Academic Staff and Graduate Students
  • Teaching programmes
  • Overview Research
  • History of Astronomy
  • Variable stars
  • Galactic structure and distance scale
  • Extragalactic large scale structure
  • Zone of Avoidance
  • Visualisation of a large-scale structure
  • Galaxy evolution and transformation
  • Near Field Cosmology

2
Members of the Astronomy Department (UCT)
Permanent Academic support staff
Emeritus and Honorary professors
Since Jan 2005
From Jun 2007
Permanent since Jan 2005 2000-2004 Senior
Research Fellow
Since Jan 2006
Honorary Professors associated with the Astronomy
Department
SAAO Math Dept. (UCT) NASSP
3
SARChI ? Research Chair in Extragalactic Radio
Astronomy At the Astronomy Department (UCT)
UWC?
Brings a lot of funding to the group in the form
of equipment, operating costs and foremost
bursaries for graduate students
4
Graduate Students of the Astronomy Department
(UCT)
6 PhD students
8 MSc students (all part of NASSP)
Plus 3 part-time external registered students -
Claire Blackman (PhD) - Pierre Vermaak (PhD) -
Denis Dale (MSc)
1 PhD and 3 MSc students (all NASSP) with primary
supervisor of SAAO
5
Postdoc positions at the Astronomy Department
(UCT)
  • Through the SARChI Chair and independently from
    the SKA bursary office (4 of the
    new graduate students are supported though SKA
    bursaries)
  • ? Advertisement of 2 postdoctoral positions
    (application deadline 1 May 2007)
  • Details on our website
  • http//mensa.ast.uct.ac.za
  • - AAS March Job Register 28345
  • We are looking for enthusiastic candidates
    interested in joining the newly formed radio
    group in extragalactic astronomy to initiate
    research projects optimized for the unique
    properties of MeerKAT. Candidates will also have
    access to the 30 South-African share on SALT and
    other optical/NIR telescopes at SAAO.
  • The successful applicants will work with Prof.
    Erwin de Blok (new SARChI Chair in Radio
    Astronomy as of June 2007) and Prof. Renée
    Kraan-Korteweg on extragalactic HI-surveys,
    galaxy evolution and aspects of radio
    interferometry.

6
  • Teaching by the Astronomy Department (UCT)
  • - A 3-year PhD programme (AST 6000W)
  • - Honours and Masters programme mostly within
    NASSP
  • All members teach in NASSP graduate programme
    (though a 2 year pure research masters is
    still possible AST5000W)
  • And T. Medupe and R. Kraan-Korteweg form part of
    local NASSP Exco
  • NASSP Honours
  • Prof. Tony Fairall - Introduction to Astronomy
    (as part of NASSP Summerschool)
  • - Galaxies
  • Dr. Patrick Woudt - General Astrophysics I
  • NASSP Masters
  • Dr. Thebe Medupe - Stellar Structure
  • Prof. Renee Kraan-Korteweg - Extragalactic
    Astronomy
  • Prof. Brian Warner - Cataclysmic Variables
  • Undergraduate Teaching

7
Undergraduate Astrophysics Specialisation (UCT)
With - AST3002F Stellar Astrophysics
-AST3003S
Galactic and Extragalactic Astronomy Cosmology
8
  • Introduced in 2006 Extramural e-learning course
  • The cosmos - an introduction to the universe
  • - An innovative ten-week course for those
    interested in basic astronomy will be offered by
    the Centre for Open Learning in April.
  • Led by Profs Tony Fairall and Brian Warner
  • offers a special opportunity to learn at your
    own pace and time.
  • ? Students can then access course notes, reading
    and any practical work required via the course
    e-learning forum from their home computer.
  • (Eight modules are to be completed during the
    10-week period of the course. Each week, a new
    module can be downloaded and studied).
  • - It draws on some of the material from the UCT
    first-year semester course in astronomy
  • It is not a UCT credit-bearing course
  • but a certificate of completion from UCT's
    Centre for Open Learning.
  • - Charge ZAR 1800. (a lot of business people,
    teachers, retired professors)

9
Research at the Astronomy Department (UCT)
Professor Renée C. Kraan-Korteweg
(HOD) Large-scale structures and streaming
motions in the nearby Universe, the zone of
avoidance, the Great Attractor systematic
HI-surveys evolution and transformation of
galaxies the dark matter content of nearby dwarf
and LSB galaxies search for intermediate black
holes Professor Anthony P. Fairall Large-scale
structures and streaming motions in the nearby
Universe the zone of avoidance active galaxies
visualisation and analysis of large-scale
structure Senior Lecturer Dr. Patrick A.
Woudt Large-scale structures and streaming
motions in the nearby Universe, the zone of
avoidance, the Great Attractor evolution and
transformation of galaxies the dark matter
content in nearby dwarf galaxies cataclysmic
variable stars, ultra-compact binaries Senior
Lecturer Dr. R.T. Medupe (UCT/SAAO) Observational
and computational modeling of variable stars
history of astronomy, Timbuktu manuscripts Honora
ry Professor Michael W. Feast Stellar evolution
galactic structure long period variable stars
distance scales Emeritus Distinguished Professor
Brian Warner Cataclysmic variable stars white
dwarf stars history of astronomy Research Chair
in Extragalactic Radio Astronomy Low surface
brightness galaxies Dark Matter interstellar
medium evolution of disk galaxies, HI sky
surveys, Radio Astronomy
10
Thebe Medupes research topics
  • Search for Astronomy in ancient manuscripts from
    West Africa (Timbuktu). We want to use these to
    attract African youth into Science
  • Numerical computations of seismic waves in stars.
    These (when compared with observations) allows us
    to infer internal structure of stars.
  • ? Diverge into
  • Cosmology and Dark Matter Studies of galaxies

11
High-speed photometry and spectroscopy of
cataclysmic variables Brian Warner and Patrick
Woudt (Univ. of Cape Town)
  • Dwarf nova oscillations (DNOs) in cataclysmic
    variables (CVs) probing the physics
  • of accretion onto white dwarfs.
  • Magnetically-channeled
  • accretion onto white dwarf.
  • Ratio of quasi-periodic oscillation
  • (QPO) to DNO in CVs is
  • similar to ratio of QPOs in
  • low-mass X-ray binaries.
  • Implications for the nature of
  • accretion onto a wide variety
  • of compact accretors (white
  • dwarfs, neutron stars and
  • black holes).
  • Specific focus on ultracompact
  • binaries (AM CVn stars) and
  • non-radially pulsating
  • accreting white dwarfs in CVs

DNOs in VW Hyi. U-band high- speed
photometry with SALTICAM (80 milliseconds). Part
of lightcurve obtained with SALT.
2 QPO-diagram for low-mass X-ray binaries (blue
dots) and CVs (red dots). CV observations
obtained with the UCT CCD on the SAAO 1-m and
1.9-m telescopes. (Warner, Woudt Pretorius
2003).
12
Distance Scale to (and) Nearby Galaxies Michael
Feast, Patricia Whitelock, John Menzies Some
Recent Highlights
Examples of reddening-free period-luminosity
relations for classical cepheids. The Cepheid
parallaxes were derived from a combination of HST
and ground-based measures (AJ in press). These
results are currently being combined with newly
revised Hipparcos parallaxes to further improve
the relations and apply them to a redetermination
of the Hubble constant (w. F van Leeuwen
Cambridge).
13
Extensive work has been carried out (IRSF) on
Local Group galaxies (like Leo I -picture) to
study their composition and evolution using AGB
variable stars (John Menzies, PAW, MWF).
Examples of Period-Luminosity relations for type
II- Cepheids in globular clusters obtained in a
Tokyo-SA collaboration (IRSF observations,
Matsunaga et al.). Work is in progress to
calibrate these relations using revised Hipparcos
parallaxes and so improve estimates of the
distances and ages of globular clusters. (van
Leeuwen (Cambridge), PAW MWF)
14
Extragalactic large-scale structures and The
ZOA An obstacle to cosmological studies
The distribution of cataloged galaxies with D
1.3
15
Extragalactic large-scale structures and The
ZOA An obstacle to cosmological studies
  • Continuity and size of superclusters/voids
    crossing the Gal. Plane
  • Local Supercluster (SGP), Great Attractor (GA),
    Perseus-Pisces Scl
  • Dipole determinations
  • Vpec(LG) ? CMB dipole requires knowledge of
    whole-sky mass distribution
  • Dynamics of the Local Group
  • possible existence of another Andromeda-like
    galaxy in the ZOA
  • Cosmic flow fields
  • (.g. in the GA region, does the galaxy
    distribution follow the mass distribution?

16
How to Peak through the Milky Way?
  • Systematic deep optical searches with
    spectroscopic follow-ups
  • ? Great Attractor
  • Future Salt, NIR, MIR
  • Systematic HI-surveys
  • The only way to probe into the most opaqe part of
    the MW (Dw1 GA)
  • Future Meerkat
  • NIR (and now MIR) Surveys
  • 2MASS ? IRSF ? Spitzer
  • (most massive spiral galaxy uncovered)

17
Dynamics of galaxy clusters in the Great
Attractor Patrick Woudt, Renée Kraan-Korteweg,
Tony Fairall (Univ. of Cape Town)
  • Norma cluster at the heart of the Great
    Attractor is the nearest rich cluster
  • in the Universe (closer than the Coma / Perseus
    clusters).
  • Use multi-wavelength (BVRJHKs) photometry of
    elliptical galaxies in the
  • Norma cluster to determine the distance (and
    motion relative to the
  • Great Attractor) of the Norma cluster (via the
    Fundamental Plane).
  • Star-crowding and extinction require a careful
    photometric analysis.
  • Probing internal dynamics of the Great Attractor
    (massive supercluster).

WKK 6269 (JHKs)
WKK 6269 (Ks)
WKK 6269 (no stars)
WKK 6269 (foreground)
WKK 6269 is the central cD galaxy in the nearby
rich Norma cluster at the core of the
Great Attractor. Image taken with IRSF at
Sutherland.
18
Evolution and transformation of galaxies in
superclusters at intermediate redshifts (z 0.15
0.60) Patrick Woudt, Renée Kraan-Korteweg,
Tony Fairall (Univ. of Cape Town)
Using SALT (multi-object spectroscopy and deep
imaging) of selected superclusters at z 0.15 ?
0.6, we aim to identify processes of galaxy
transformation within the extended supercluster
environment. Transformation processes,
transition stages and time scales as a function
of supercluster properties (richness, mass,
relaxation of individual clusters), location
within the supercluster (as a function of virial
radii from the clusters outskirts?)
and (super)cluster dynamics. Benefits of SALT
wide field of view, blue sensitivity,
multi-object spectroscopy. Coverage L 6 mag
(dwarf population)
? Abell 1445, a central cluster in a supercluster
at z 0.17 (SDSS gri colour image)
19
The recently completed 6dF Galaxy Survey Example
cross-section of large-scale structures and
voids (the dots are galaxies). Some regions
show a high density of galaxies with small voids
intervening regions have low density and
large voids.
The width of this slide is about a billion light
years
20
Back to the ZOA Galaxies known within b 5
before MB survey
Galaxies (1036) discovered with the Parkes MB HI
Survey Follow-up with MeerKat deeper and solve
for controversy GA vs Shapley
concentration
21
Mapping the Norma Great Wall footprint in the NIR
(IRSF at SAAO) and MIR (Spitzer)
Footprint 55 ?º (a) Spitzer IRAC 36s (Glimpse
2s) per pointing ? 175 hrs Not successful 2006
? But other ZOA other area!!! (b) IRSF 4050
fields ? 700 hrs
22
New Mosaic Two highly obscured (AB 19 mag)
spiral galaxies
At l 317.04, b -0.50 l 316,87, b
-0.60 AB 10 mag Any connection with the GA?
23
Superposition of HI contours (ATCA April 2006) on
Glimpse image
Jarrett et al. 2007
? the 2 Glimpse galaxies are confirmed ? they
lie at the distance of the GA overdensity ? they
have typical HI masses for normal star-forming Sb
or Sc MHI 2.2 109 Msun and 1.1 109Msun
respectively (H072)
24
HIZOA J0836-43 the most HI-massive galaxy
known? Donley et al. (2006)
Image AAT K-band. Contours ATCA HI.
  • MHI7x1010 Msun (more massive than Malin-1)
  • Mtot1.1x1012 Msun
  • AB12 mag (b-1.6o)
  • Diameter 100 kpc (10 revolutions in 14 Gyr)

25
Predictions galaxy formation models
  • Hierarchical galaxy formation
  • The most massive present-day galaxies were formed
    at z 1 (e.g. Mo et al. 1998, van den Bosch
    1998)
  • The number of massive galaxies should decline
    exponentially above a characteristic value, M.
    From the HIPASS BGC HI mass function, M 6x109
    M

Zwaan et al. 2003
26
Dark Matter in Galaxies Erwin de Blok (soon UCT)
  • Dark matter is the most important mass ingredient
    of our universe
  • But we do not understand it
  • Cosmological computer simulations make excellent
    predictions of the large scales (clusters of
    galaxies)

Springel et al 2005
27
Small Scale Dark Matter
  • The simulations give incorrect predictions for
    the distribution of DM at galaxy scales
    cosmologys Achilles heel
  • High-resolution observations of the dynamics of
    gas and stars in nearby galaxies can possibly
    measure the DM distribution

28
HI Nearby Galaxy Survey
  • Largest and highest resolution set of galaxy
    radio observations ever
  • Combined with GALEX and Spitzer full view of
    baryons and proper physics
  • Best chance of measuring DM in galaxies
  • Constrain Cosmology
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