Dear Colleagues,
The Magellanic Clouds Working Group is pleased to bring you
issue 79 of the Magellanic Clouds Newsletter. In this issue, we
present 6 submitted abstracts, an announcement for an upcoming meeting
on high energy sources in galaxies, an opportunity for students you
may be working with, and a collection of recent astro-ph listings of
potential interest to Magellanic Clouds researchers. As always, this
month's issue is available from the MC News Website in a variety of
formats (PDF, HTML, PostScript, and LATEX).
Best Regards,
Bryan Dunne
Editor, MC News
205th American Astronomical Society Meeting
9-13 January 2005
Populations of High-Energy Sources in Galaxies
15-19 August 2005 width 0.5pt
This work represent the first major study of the optical and IR
characteristics of the mass donor companions to the X-ray pulsars in
the Small Magellanic Cloud (SMC). In this work several new
counterparts have been identified, and possible ones confirmed, as
companions to X-ray pulsars in the SMC giving a total of 34 such
objects now identified. In addition this work presents three new
binary periods and confirms two X-ray periods using optical data for
objects in this group. This homogeneous sample has been studied as a
group to determine important general characteristics that may offer
insight into the evolution of such systems. In particular, the
spectral class distribution shows a much greater agreement with those
of isolated Be stars, and appears to be in some disagreement with the
galactic population of Be stars in Be/X-ray binaries. Studies of the
long term optical modulation of the Be star companions reveal an
extremely variable group of objects, a fact which will almost
certainly make a major contribution to the pronounced X-ray
variability. The spatial distribution of these systems within the SMC
is investigated and strongly suggests a link between massive star
formation and the HI density distribution. Finally, studies of the
circumstellar disk characteristics reveal a strong link with optical
variability offering important clues into the long-term stability of
such disks.
Comments: Accepted for publication in MNRAS
WWW: www.astro.soton.ac.uk/
mjc/oid.ps.gz
e-mail: mjcoe@soton.ac.uk
We carried out deep near-infrared imaging observations of the
N159/N160 complex star forming region in the Large Magellanic Cloud
(LMC). We observed an area of 380 arcmin
( 80,000
pc at the distance of the LMC) in the 
, 
, and 
bands. The observations are deep enough to detect down to 3
M
Herbig Ae/Be stars in the LMC. We discovered a total of 338
and 464 candidates of Herbig Ae/Be and OB stars, respectively, based
on the near-infrared colors and magnitudes. The Herbig Ae/Be star
candidates constitute 10 clusters, while the OB star candidates 13. We
discovered an embedded Herbig Ae/Be cluster in the N159E giant
molecular cloud (GMC) and a Herbig Ae/Be cluster at a north-east tip
of the N159S GMC. Together with neighboring two H II regions, the
Herbig Ae/Be cluster at a tip of the N159S GMC indicates a hint of the
beginning of sequential cluster formation in N159S. Spatial
distributions of the Herbig Ae/Be and OB clusters, in conjunction with
previously known optical clusters and embedded massive stars, indicate
(1) sequential cluster formation within each of the N159 and N160 star
forming regions, and (2) large scale sequential cluster formation over
the entire observed region from N160 to N159S. Possible triggers for
the large scale sequential cluster formation are a supergiant shell
SGS19 and an expanding superbubble. Some Herbig Ae/Be clusters in the
N159/N160 complex are significantly larger in spatial scale than
pre-main sequence clusters of similar age in the Galaxy. Highly
turbulent gas motion in the LMC is probably responsible for forming
the large young clusters.
Comments: accepted by the Astronomical Journal
WWW: http://optik2.mtk.nao.ac.jp/yas/preprint/preprint0410.pdf
e-mail: yas@optik.mtk.nao.ac.jp
We present ultraviolet spectra from the Space Telescope Imaging
Spectrograph (STIS) of 12 early B-type stars in the Small Magellanic
Cloud (SMC), comprising 9 supergiants and 3 giants. A morphological
comparison with Galactic analogues is made using archival data from
the International Ultraviolet Explorer (IUE). In general, the
intensity of the P Cygni emission in the UV resonance lines is
greater, and seen to later spectral types, in the Galactic spectra
than in their metal-deficient SMC counterparts; we attribute these
effects as most likely arising from weaker stellar winds in the SMC
targets, as predicted by radiatively driven wind theory. We also
include unpublished STIS observations of two late O-type stars in the
SMC. In combination with the B-type observations, and published
O-type data, we now have an extensive ultraviolet spectral library of
metal-deficient stars, of use in the study of unresolved starbursts
and high redshift, star-forming galaxies. In this context, we present
empirical measurements for the B-type spectra of the new `1978 index'
suggested by Rix et al. as a probe of metallicity in such systems.
Comments: Accepted by PASP
WWW: http://www.ing.iac.es/cje/bstars.ps.gz
e-mail: cje@ing.iac.es
We present a high quality CMD for a 36' 
36' field located 8
degrees (
kpc) from the LMC center, as well as a precise
determination of the LMC surface brightness derived from the resolved
stellar population out to this large galactocentric radius. This deep
CMD shows for the first time the detailed age distribution at this
position, where the surface brightness is 
26.5
mag/''. At a radius R
474' the main sequence is well
populated from the oldest turnoff at 
to the 2.5 Gyr
turnoff at 
. Beyond this radius, a relatively strong
gradient in the density of stars with ages in the 2.5-4 Gyr
range is apparent. There are some stars brighter and bluer than the
main population, quite uniformly distributed over the whole area
surveyed, which are well matched by a 1.5 Gyr isochrone and may be
indicative of a relatively recent star formation, or merger,
event. The surface brightness profile of the LMC remains exponential
to this large galactocentric radius and shows no evidence of disk
truncation. Combining the information on surface brightness and
stellar population we conclude that the LMC disk extends (and
dominates over a possible stellar halo) out to a distance of at least
7 kpc. These results confirm that the absence of blue stars in the
relatively shallow off-center CMDs of dIrr galaxies is not necessarily
evidence for an exclusively old stellar population resembling the halo
of the Milky Way.
Comments: Accepted by: ApJ Letters: ApJ, 614, L109
WWW: http://xxx.lanl.gov/abs/astro-ph/0409023
e-mail: carme@iac.es
We have conducted a programme to determine the fundamental parameters
of a substantial number of eclipsing binaries of spectral types O and
B in the Small Magellanic Cloud. New spectroscopic data, obtained with
the two-degree-field multi-object spectrograph on the 3.9-m
Anglo-Australian Telescope, have been used in conjunction with
photometry from the Optical Gravitational Lens Experiment (OGLE-II)
database of SMC eclipsing binaries. Previously we reported results for
10 systems; in this second and concluding paper we present spectral
types, masses, radii, temperatures, surface gravities and luminosities
for the components of a further 40 binaries. The full sample of 50
OB-type eclipsing systems is the largest single set of fundamental
parameters determined for high-mass binaries in any galaxy. We find
that 21 of the systems are in detached configurations, 28 are in
semi-detached post-mass-transfer states, and one is a contact binary.
Each system provides a primary distance indicator. We find a mean
distance modulus to the SMC of 18.91+/-0.03+/-0.1 (internal and
external uncertainties; D=60.6+/-1.0 kpc). This value represents one
of the most precise available determinations of the distance to the
SMC.
Comments: paper accepted on 22 November 2004 for publication in MNRAS.
WWW: astro-ph/0411672
e-mail: rwh@st-andrews.ac.uk
We present the single stellar population (SSP) synthesis results of
our new synthetic stellar atmosphere models library with a spectral
sampling of 0.3 Å, covering the wavelength range from 3000 Å to
7000Å for a wide range of metallicities (twice solar, solar, half
and 1/10 solar). The stellar library is composed of 1650 spectra
computed with the latest improvements in stellar atmospheres. In
particular it incorporates non-LTE line-blanketed models for hot
(T
27500 K) and LTE line-blanketed models
(Phoenix) for cool (3000 K 
T
4500 K)
stars. Because of the high spectral resolution of this library,
evolutionary synthesis models can be used to predict the strength of
numerous weak absorption lines, and the evolution of the profiles of
the strongest lines over a wide range of ages. The SSP results have
been calculated for ages 1 Myr to 17 Gyr using the stellar
evolutionary provided by the Geneva and Padova-tracks groups. For
young stellar populations, our results have a very detailed coverage
of high-temperature stars with similar results for Padova and Geneva
isochrones. For intermediate and old stellar populations, our results,
once degraded to a lower resolution, are similar to the ones obtained
by other groups apart from limitations imposed by the stellar
evolutionary physics. The limitations and advantages of our library
for the analysis of integrated populations are described. The full set
of the stellar library and the evolutionary models are available here
for retrieval or on request from authors.
Comments: Accepted by: M.N.R.A.S.
WWW: http://www.iaa.es/rosa/
e-mail: rosa@iaa.es, mcs@iaa.es
At its meeting in Mexico City on 25 May 2004, the Executive Committee
of the International Astronomical Union accepted the proposal for an
IAU Symposium on "Populations of High-Energy Sources in Galaxies",
to be held 15-19 August 2005 in Dublin, Ireland. This will be IAU
Symposium No. 230. The venue will be Dublin Castle, in the centre of
town.
With currently operational high-energy satellite observatories the
potential for conducting detailed studies of individual sources of
high-energy radiation in other galaxies as well as in our own Milky Way
has greatly increased.
The primary objectives for this Symposium are:
Information on IAU Symposium number 230 is available via
http://www.dunsink.dias.ie/IAUS230/index.html
The Scientific Organizing Committee is composed of: E.J.A. Meurs
(Ireland, Chair), G. Fabbiano (USA, Co-Chair), L. Bassani (Italy),
B. McBreen (Ireland), H.-Y. Chu (USA), C. Done (UK), G. Hasinger
(Germany), G. Koenigsberger (Mexico), K. Koyama (Japan), V. Lipunov
(Russia),M.Mas-Hesse (Spain), Th. Montmerle (France), G. Romero
(Argentina), Z. Wang (China).
The Local Organizing Committee consists of: B. McBreen (Chair),
C. del Burgo, C. Handley, L. Norci, C. Melody, C. Woods.
The anticipated time timetable is:
October 2004 : 1st Announcement
15 December 2004 : deadline for pre-registration
January 2005 : 2nd Announcement
April 2005 : Final Announcement
1 June 2005 : Registration Deadline
15 August 2005 : Symposium programme starts
The purpose of the pre-registration is to gauge the interest in this
Symposium, so as to assist SOC and LOC with their organization. The
2nd Announcement will contain the call for registration, information
about hotel reservations, abstract submission, posters, proceedings,
IAU travel grants, invited speakers and sponsorship.
Please circulate this 1st Announcement in your Institute or
University Department and to colleagues elsewhere that may be
interested. We try to avoid this notice being sent more than once to
you, but occasionally your e-mail address might occur in more than one
of our mailing lists.
With best regards,
Evert Meurs and Pepi Fabbiano (SOC Co-Chairs)
Brian McBreen (LOC Chair)
The recently founded International Max-Planck Research School
for Astronomy and Cosmic Physics (IMPRS) at the University of
Heidelberg invites applications for its Ph.D. program.
The school is located in Heidelberg (Germany) which is one of the most beautiful old university towns in Europe. We offer outstanding research and training opportunities with excellent instrumental, observational, and theoretical research facilities at five first-rate institutes, namely
The main research topics at these five institutions are:
Planet and star formation - extrasolar planets and substellar objects
- astrometry - formation, evolution and dynamics of galaxies - active
galactic nuclei and massive black holes - gravitational lensing -
cosmology and structure formation - high energy astrophysics, cosmic
rays and the search for non-baryonic dark matter - state-of-the-art
instrumentation for astronomy and astroparticle physics.
IMPRS for Astronomy and Cosmic Physics at the University of
Heidelberg has established a comprehensive curriculum including
regular lectures, seminars, invited guest lectures, and advanced
summer schools. Ph.D. research projects will be defined and
supervised by scientists at one of the participating institutes.
IMPRS Heidelberg is open for students from all countries and
offers several 3-year Ph.D. fellowships for both international and
national students. Interested students are invited to apply by 15
January 2005 for the academic year starting in September 2005. In
general, applicants should have a Masters or Diploma in Physics or
Astronomy (or equivalent) including a corresponding thesis. Successful
applicants will receive financial support through a PhD fellowship.
For further details on IMPRS Heidelberg and the application
procedure, we refer to our web-site at
http://www.mpia-hd.mpg.de/imprs-hd/
Under /poster2.html you will also find a poster of IMPRS
Heidelberg. We would be happy if you further distribute it among
other colleagues and interested students. Thank you in advance for
your support.
With kind regards,
Christian Fendt
Coordinating Scientist
International Max Planck School for Astronomy and Cosmic Physics at the
University of Heidelberg