Spectroscopy:Spectroscopy:High angular resolution withHigh angular resolution with

selectable spectral resolutionselectable spectral resolution

(or addressing the scientific problem with the (or addressing the scientific problem with the optimal sampling)optimal sampling)

Motivation:Motivation:All too often spectrographs are designed for maximum All too often spectrographs are designed for maximum

throughput at one spectral resolution.throughput at one spectral resolution.HST breakthrough: near-diffraction-limited imagery AND HST breakthrough: near-diffraction-limited imagery AND

access to the UV.access to the UV.Desire: maximum throughput AND high angular resolution Desire: maximum throughput AND high angular resolution

AND appropriate resolving power AND appropriate resolving power COS: maximum throughput (!), resolving power matched to COS: maximum throughput (!), resolving power matched to

IGM studies--one internal reflectionIGM studies--one internal reflectionSTIS: high angular resolution (!), selectable resolving power STIS: high angular resolution (!), selectable resolving power

--four internal reflections (+ two for HST aberration)--four internal reflections (+ two for HST aberration)(2 out of 3 ain’t bad… can’t do faster, better, cheaper at the (2 out of 3 ain’t bad… can’t do faster, better, cheaper at the

same time either)same time either)

Astronomical sources do not form in isolation:Astronomical sources do not form in isolation:

QSO’s, AGN’s, nuclear black holes--- form in host galaxiesQSO’s, AGN’s, nuclear black holes--- form in host galaxies

Star formation regions, globular clustersStar formation regions, globular clusters

HII regions, propylyds, recently formed starsHII regions, propylyds, recently formed stars

Protoplanetary disks, Planetary systemsProtoplanetary disks, Planetary systems

Binary starsBinary stars

Stars with massive windsStars with massive winds

Stars with ejecta: PNs, shells, etc.Stars with ejecta: PNs, shells, etc.

Breakthroughs come through spatially resolving these Breakthroughs come through spatially resolving these complex systems; interactions can be studied in detailcomplex systems; interactions can be studied in detail

An example of what we have learned that is An example of what we have learned that is uniquely possible with HST/STIS: uniquely possible with HST/STIS: Eta Carinae and the HomunculusEta Carinae and the Homunculus

Massive star with Massive star with bipolar ejecta bipolar ejecta originating in the originating in the 19th century.19th century.

N-rich, C-, O-N-rich, C-, O-depleted… depleted…

Metals abound!Metals abound!

IUE: 10”x20” apertureR=10,000

R=1500 R=1500

HST/GHRS: 0.25”HST/GHRS: 0.25”

Eta Carinae

Weigelt Blobs 0.25” (500AU) distance

HST/STIS: echelle 0.3” (0.060”, R=40,000)HST/STIS: echelle 0.3” (0.060”, R=40,000)

June 22, 2003

July 5, 2003

HST/STIS CCD 52”X0.1”, R=8000HST/STIS CCD 52”X0.1”, R=8000June 22, 2003

July 5, 2003 (periastron)

Spatially resolved spectra centered on [Ar III] and [Fe II] (near 7137A) R=1500 R=1500

PA=-28o

PA=+22o

[Ar III] is blueshifted from 0 to 500 km/s along disk. [Fe II] is centered on -40 km/s

6490 A 7050 A

52x0.2F1 apertureH alphaScattered starlight

Shock at edge

External Nebulosity

Little Homunculus

He I 6678 A

[Ni II] 6666 A

Sr

Filament

Homunculus internal structures

52x0.2F1

Aperture Position

0.55” Fiducial

Spatial: 18”

H absorption

Spectral Dispersion ---->Spectral Dispersion ---->

What HST/STIS Imaging Spectroscopy has discovered What HST/STIS Imaging Spectroscopy has discovered about Eta Carinae:about Eta Carinae:

Little Homunculus-- a bipolar shell within the Homunculus, ejected in the Little Homunculus-- a bipolar shell within the Homunculus, ejected in the 1890s, 50 years after the massive event.1890s, 50 years after the massive event.

Strontium filament-- a metal-ionized region (7-8 eV photons), not H II region, 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 in the skirt… evidence of very peculiar abundances caused by chemistry, not nuclear processes????… Ti II emission region… Ti/Ni ~40X solar!nuclear processes????… Ti II emission region… Ti/Ni ~40X solar!

Homunculus shell structure of metals and molecules leading to abundance Homunculus shell structure of metals and molecules leading to abundance analysis of ejecta. Potential leading to understanding of how dust can form in analysis of ejecta. Potential leading to understanding of how dust can form in gas depleted 50-fold of both C and O.gas depleted 50-fold of both C and O.

First identification of IS vanadium, scandium, strontiumFirst identification of IS vanadium, scandium, strontium Characterization and modeling of 760K and 6400K photoexcited gases!Characterization and modeling of 760K and 6400K photoexcited gases! Tracking of photo-excitation and ionization changes in ejecta across binary period.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 Identification of the He I emission originating in the primary massive wind, yet excited by the hot, lower mass secondaryexcited by the hot, lower mass secondary

Resolution of the massive binary wind structure leading to 3-D modeling of Resolution of the massive binary wind structure leading to 3-D modeling of wind-wind interaction… including clumpingwind-wind interaction… including clumping

Combined withCombined withCHANDRA: characterization of the wind-wind interaction and binaryCHANDRA: characterization of the wind-wind interaction and binaryVLT/UVES: abundances of metals and diatomic moleculesVLT/UVES: abundances of metals and diatomic moleculesVLTI/AMBER: measure of the He I wind-wind structure of binary systemVLTI/AMBER: measure of the He I wind-wind structure of binary system

Models to be tested across the 2009.0 periastron passage.Models to be tested across the 2009.0 periastron passage.

Future Spectroscopy:Future Spectroscopy:

We must take full advantage of spatial resolution along We must take full advantage of spatial resolution along with appropriate spectral resolution where possible--with appropriate spectral resolution where possible--

(increased detail can lead to greatly expanded insights).(increased detail can lead to greatly expanded insights).

Two basic designs:Two basic designs:

Maximize throughput at appropriate resolution Maximize throughput at appropriate resolution at expense of spatial resolutionat expense of spatial resolution

Optimize spatial and spectral resolutionOptimize spatial and spectral resolution

requires more optical surfaces, requires more optical surfaces,

at the expense of throughput.at the expense of throughput.

Can we bring both designs together?Can we bring both designs together?

Sampling: (science tradeoffs must be addressed!)Sampling: (science tradeoffs must be addressed!)

Long slitLong slit

Integral FieldIntegral Field

Aperture selectorsAperture selectors

Acknowledgement:Acknowledgement:

NASA/GSFC for sponsoring the decades of UV NASA/GSFC for sponsoring the decades of UV spectroscopic development… spectroscopic development… will options exist for future development?will options exist for future development?

STScI for support through multiple guest observer STScI for support through multiple guest observer programs (approaching one paper per allocated orbit)programs (approaching one paper per allocated orbit)

Eta Lunch Bunch and the extended Eta Car teamsEta Lunch Bunch and the extended Eta Car teams