GO 12465/13052: A Massive Star Census of the Starburst
Cluster
R136
PI: Paul Crowther
CoI's: Chris Evans, Danny Lennon, Alex De Koter, Jorick
Vink, Artemio Herrero, Norbert Langer, Nolan Walborn, Jesus
Maiz-Apellaniz, Jo Puls, Goetz Grafener, Alceste
Bonanos, Hugues Sana, Selma de Mink, Ines Brott, Ian Howarth
This 39 orbit Cycle 19 (GO 12465) + Cycle 20 (GO 13052) programme with
HST/STIS complements the ongoing ESO/VLT Large Programme VLT-FLAMES Tarantula Survey (Chris Evans, PI) and
30 orbit Cycle 19+21 proper motion study of 30 Doradus with WFC3 and
ACS (GO 12499, Danny Lennon, PI).
Abstract
We propose to carry out a comprehensive census of the most
massive stars in the central parsec (4 arcsec) of the starburst cluster,
R136, which powers the Tarantula Nebula in the LMC. R136 is both
sufficiently massive that the upper mass function is richly populated and
young enough that its most massive stars have yet to explode as
supernovae. The identification of
very massive stars in R136, up to 300 solar masses, raises general questions of star
formation, binarity and feedback in young massive clusters. The proposed
STIS spectral survey of ~36 stars more massive than ~50 solar masses
within R136 is ground-breaking, of legacy value, and is specifically
tailored to:
- a) yield physical properties;
- b) detect the majority of binaries by splitting observations between
Cycles 19 and 20;
- c) measure rotational velocities, relevant for predictions of
rotational mixing;
- d) quantify mass-loss properties for very massive stars;
- e) determine surface compositions;
- f) measure radial velocities, relevant for runaway stars and cluster
dynamics;
- g) quantify radiative and mechanical feedback.
This census will enable the mass function of very massive stars to
be measured for the first time, as a result of incomplete and inadequate
spectroscopy to date. It will also perfectly complement our
Tarantula Survey, a ground-based VLT Large
Programme, by including the most massive stars that are inaccessible to
ground-based visual spectroscopy due to severe crowding. These surveys,
together with existing integrated UV and optical studies will enable 30
Doradus to serve as a bona-fide template for unresolved extragalactic
starburst regions.
Observing Description: Complete UV/optical scan
across LMC star cluster R136 with 17 slits (width 0.2 arcsec) as shown
in the figure, superimposed upon a F555W WFC3/UVIS Early Release
Observation (green labels are illustrative magnitudes for the circled
stars). Due to
severe crowding in cluster core, initial acquisition (+peakup) is of an
isolated bright star Melnick 34. Offset positions and position angle 64
degrees (E of N) are selected to ensure that both R136a1 and a2 are
included in NW1 slit.
Cycle 19 (GO 12465)
- Visit 01 (4 orbits): STIS/CCD (G430M/3936) SE9 to NW1 (6 Apr
2012 @ 03:33)
- Visit 07 (3 orbits): STIS/CCD (G430M/3936) NW2 to NW8 (20 Oct
2012 @ 12:08)
- Visit 02 (4 orbits): STIS/CCD (G430M/4451) SE9 to NW1 (4 Apr
2012 @ 15:22)
- Visit 08 (3 orbits): STIS/CCD (G430M/4451) NW2 to NW8 (20 Oct 2012
@ 20:29)
- Visit 03 (4 orbits): STIS/CCD (G430M/4706) SE9 to NW1 (6 Apr
2012 @ 13:48)
- Visit 09 (3 orbits): STIS/CCD (G430M/4706) NW2 to NW8 (23 Oct
2012 @ 10:00)
- Visit 04 (4 orbits): STIS/MAMA (G140L) SE9 to NW3 (7 Apr 2012 @ 06:39)
- Visit 05 (2 orbits): STIS/MAMA (G140L) NW4 to NW8 (8 Apr 2012 @ 06:34)
- Visit 06 (5 orbits): STIS/CCD (G750M/6581) SE9 to NW8 (23 Oct
2012 @ 01:54)
Cycle 20 (GO 13052)
- Visit 01 (4 orbits): STIS/CCD (G430M/4194) SE9 to NW1 (21 Oct 2012 @
12:16)
- Visit 02 (3 orbits): STIS/CCD (G430M/4194) NW2 to NW8 (3 Apr 2013 @
16:12)
25-Mar-2013paul.crowther@shef.ac.uk