Transcript Theodore`s presentation

Spectroscopy:
High angular resolution with
selectable spectral resolution
(or addressing the scientific problem with the
optimal sampling)
Motivation:
All too often spectrographs are designed for maximum
throughput at one spectral resolution.
HST breakthrough: near-diffraction-limited imagery AND
access to the UV.
Desire: maximum throughput AND high angular resolution
AND appropriate resolving power
COS: maximum throughput (!), resolving power matched to
IGM studies--one internal reflection
STIS: high angular resolution (!), selectable resolving power
--four internal reflections (+ two for HST aberration)
(2 out of 3 ain’t bad… can’t do faster, better, cheaper at the
same time either)
Astronomical sources do not form in isolation:
QSO’s, AGN’s, nuclear black holes--- form in host galaxies
Star formation regions, globular clusters
HII regions, propylyds, recently formed stars
Protoplanetary disks, Planetary systems
Binary stars
Stars with massive winds
Stars with ejecta: PNs, shells, etc.
Breakthroughs come through spatially resolving these
complex systems; interactions can be studied in detail
An example of what we have learned that is
uniquely possible with HST/STIS:
Eta Carinae and the Homunculus
Massive star with
bipolar ejecta
originating in the
19th century.
N-rich, C-, Odepleted…
Metals abound!
R=1500
R=1500
IUE: 10”x20” aperture
R=10,000
HST/GHRS: 0.25”
Eta Carinae
Weigelt Blobs 0.25” (500AU) distance
HST/STIS: echelle 0.3” (0.060”, R=40,000)
June 22, 2003
July 5, 2003
HST/STIS CCD 52”X0.1”, R=8000
June 22, 2003
July 5, 2003 (periastron)
Spatially resolved
spectra centered on
[Ar III] and [Fe II]
(near 7137A)
R=1500
PA=-28o
[Ar III] is blueshifted from
0 to 500 km/s along disk.
[Fe II] is centered on -40
km/s
PA=+22o
R=1500
Homunculus
internal
structures
Spatial: 18”
Little
Homunculus
H alpha
Scattered
starlight
52x0.2F1 aperture
Shock at
edge
Ha absorption
Sr
Filament
0.55” Fiducial
52x0.2F1
Aperture Position
He I 6678 A
[Ni II] 6666 A
Spectral Dispersion ---->
External Nebulosity
6490 A
7050 A
What HST/STIS Imaging Spectroscopy has discovered
about Eta Carinae:
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Little Homunculus-- a bipolar shell within the Homunculus, ejected in the
1890s, 50 years after the massive event.
Strontium filament-- a metal-ionized region (7-8 eV photons), not H II region,
in the skirt… evidence of very peculiar abundances caused by chemistry, not
nuclear processes????… Ti II emission region… Ti/Ni ~40X solar!
Homunculus shell structure of metals and molecules leading to abundance
analysis of ejecta. Potential leading to understanding of how dust can form in
gas depleted 50-fold of both C and O.
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First identification of IS vanadium, scandium, strontium
Characterization and modeling of 760K and 6400K photoexcited gases!
Tracking of photo-excitation and ionization changes in ejecta across binary period.
Identification of the He I emission originating in the primary massive wind, yet
excited by the hot, lower mass secondary

Resolution of the massive binary wind structure leading to 3-D modeling of
wind-wind interaction… including clumping
Combined with
CHANDRA: characterization of the wind-wind interaction and binary
VLT/UVES: abundances of metals and diatomic molecules
VLTI/AMBER: measure of the He I wind-wind structure of binary system
Models to be tested across the 2009.0 periastron passage.

Future Spectroscopy:
We must take full advantage of spatial resolution along with
appropriate spectral resolution where possible-(increased detail can lead to greatly expanded insights).
Two basic designs:
Maximize throughput at appropriate resolution
at expense of spatial resolution
Optimize spatial and spectral resolution
requires more optical surfaces,
at the expense of throughput.
Can we bring both designs together?
Sampling: (science tradeoffs must be addressed!)
Long slit
Integral Field
Aperture selectors
Acknowledgement:

NASA/GSFC for sponsoring the decades of UV
spectroscopic development…
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will options exist for future development?
STScI for support through multiple guest observer
programs (approaching one paper per allocated orbit)
Eta Lunch Bunch and the extended Eta Car teams