HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5092

PERIOD COVERED: 5am May 7 - 5am May 10, 2010 (DOY 127/09:00z-130/09:00z)

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)

HSTARS:

12270 - REAcq(1,2,1) at 129/19:25:47z took 3 attempts to succeed. the

           first two attempts resulted in scan step limit exceeded on FGS1.

           Previous GSAcq(1,2,1) at 129/17:58:12z was successful on the first

           attempt.

12271 - GSAcq(2,0,2) at 130/06:34:11z failed to RGA control due to scan

           step limit exceeded on FGS 2.

           Observations affected: Astrometry proposal ID#11704.

COMPLETED OPS REQUEST:

18855-0 - Null Genslew for proposal 12077 - slot 1 @ 127/1911z

COMPLETED OPS NOTES: (None)

                       SCHEDULED  SUCCESSFUL

FGS GSAcq               28             27      

FGS REAcq               18             18      

OBAD with Maneuver 18             18      

SIGNIFICANT EVENTS: (None)

OBSERVATIONS SCHEDULED

WFC3/IR/S/C 12089

Persistence - Part 2

The IR detectors on WFC3, like other IR detectors, trap charge when

exposed to sources near or above the full well of the detector diodes.

This charge leaks out, producing detectable afterglow images for periods

which can last for several hours, depending on the amount of over

exposure. These visits, which consist of tungsten lamp exposures of

varying durations followed by darks, are intended to provide a better

calibration of persistence over the full area of the IR detector of

WFC3.

WFC3/UV 12077

Monitoring the Aftermath of an Asteroid Impact Event

Our Director's Discretionary program (GO-12053) to image the newly

discovered object P/2010 A2 executed successfully on 2010 Jan 25 and 29

with spectacular results. Hubble has apparently borne witness to the

first detection of a collision in the asteroid belt. Hubble imaging with

the WFC3 has revealed an object unlike anything ever seen before and

with details impossible to detect with any other facility. We request 6

more orbits of Hubble time (1 orbit every 20 days over the next few

months, until the object enters Hubble's solar exclusion zone in

late-June 2010) to monitor the evolution of this remarkable object and

further clarify the nature of this event. These observations may usher

in a new era of searching for and characterizing collisional events

within the asteroid belt.

ACS/WFC 11995

CCD Daily Monitor (Part 2)

This program comprises basic tests for measuring the read noise and dark

current of the ACS WFC and for tracking the growth of hot pixels. The

recorded frames are used to create bias and dark reference images for

science data reduction and calibration. This program will be executed

four days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To

facilitate scheduling, this program is split into three proposals. This

proposal covers 320 orbits (20 weeks) from 1 February 2010 to 20 June

2010.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more

reliably removed from science data using darks taken with the same

exposure sequences as the science data, than with a single dark current

image scaled by desired exposure time. Therefore, dark current images

must be collected using all sample sequences that will be used in

science observations. These observations will be used to monitor changes

in the dark current of the WFC3-IR channel on a day-to-day basis, and to

build calibration dark current ramps for each of the sample sequences to

be used by Gos in Cycle 17. For each sample sequence/array size

combination, a median ramp will be created and delivered to the

calibration database system (CDBS).

WFC3/IR 11926

IR Zero Points

We will measure and monitor the zeropoints through the IR filters using

observations of the white dwarf standard stars, GD153, GD71 and GD191B2B

and the solar analog standard star, P330E. Data will be taken monthly

during Cycle 17. Observations of the star cluster, NGC 104, are made

twice to check color transformations. We expect an accuracy of 2% in the

wide filter zeropoints relative to the HST photometric system, and 5% in

the medium- and narrow-band filters.

WFC3/UVIS 11924

WFC3/UVIS External and Internal CTE Monitor

CCD detector Charge Transfer Inefficiency (CTI)-induced losses in

photometry and astrometry will be measured using observations of the

rich open cluster NGC6791 and with the EPER (Extended Pixel Edge

Response) method using tungsten lamp flat field exposures. Although we

do not expect to see CTE effects at the outset of Cycle 17, this CTE

monitoring program is the first of a multi-cycle program to monitor and

establish CTE-induced losses with time. We expect to measure CTE effects

with a precision comparable to the ACS measurements.

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the

UVIS detector (both CCDs) at the level of ~1%, lasting hours to days.

Initially found via an unexpected bowtie-shaped feature in flatfield

ratios, subsequent lab tests on similar e2v devices have since shown

that it is also present as simply an overall offset across the entire

CCD, i.e., a QE offset without any discernable pattern. These lab tests

have further revealed that overexposing the detector to count levels

several times full well fills the traps and effectively neutralizes the

bowtie. Each visit in this proposal acquires a set of three 3x3 binned

internal flatfields: the first unsaturated image will be used to detect

any bowtie, the second, highly exposed image will neutralize the bowtie

if it is present, and the final image will allow for verification that

the bowtie is gone.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set of

full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K

subarray biases are acquired at less frequent intervals throughout the

cycle to support subarray science observations. The internals from this

proposal, along with those from the anneal procedure (Proposal 11909),

will be used to generate the necessary superbias and superdark reference

files for the calibration pipeline (CDBS).

STIS/MA1 11861

MAMA FUV Flats

This program will obtain FUV-MAMA observations of the STIS internal

Krypton lamp to construct an FUV flat applicable to all FUV modes.

STIS/CC 11847

CCD Bias Monitor-Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1,

and 1x1 at gain = 4, to build up high-S/N superbiases and track the

evolution of hot columns.

STIS/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

WFC3/IR 11838

Completing a Flux-limited Survey for X-ray Emission from Radio Jets

We will measure the changing flow speeds, magnetic fields, and energy

fluxes in well-resolved quasar jets found in our short-exposure Chandra

survey by combining new, deep Chandra data with radio and optical

imaging. We will image each jet with sufficient sensitivity to estimate

beaming factors and magnetic fields in several distinct regions, and so

map the variations in these parameters down the jets. HST observations

will help diagnose the role of synchrotron emission in the overall SED,

and may reveal condensations on scales less than 0.1 arcsec.

FGS 11789

An Astrometric Calibration of Population II Distance Indicators

In 2002, HST produced a highly precise parallax for RR Lyrae. That

measurement resulted in an absolute magnitude, M(V)= 0.61+/-0.11, a

useful result, judged by the over ten refereed citations each year

since. It is, however, unsatisfactory to have the direct,

parallax-based, distance scale of Population II variables based on a

single star. We propose, therefore, to obtain the parallaxes of four

additional RR Lyrae stars and two Population II Cepheids, or W Vir

stars. The Population II Cepheids lie with the RR Lyrae stars on a

common K-band Period-Luminosity relation. Using these parallaxes to

inform that relationship, we anticipate a zero point error of 0.04

magnitude. This result should greatly strengthen confidence in the

Population II distance scale and increase our understanding of RR Lyrae

star and Pop. II Cepheid astrophysics.

WFC3/UV/ACS/WFC 11739

Multiple Stellar Generations in the Unique Globular Clusters NGC 6388

and NGC 6441

Over the last few years HST observations have resulted in one of the

most exciting and unexpected developments in stellar population studies:

the discovery of multiple generations of stars in several globular

clusters. The finding of multiple main sequences in the massive clusters

NGC 2808 and Omega Centauri, and multiple subgiant branches in NGC 1851,

M54, and NGC 6388 has challenged the long-held paradigm that globular

clusters are simple stellar populations. Even more surprising, given the

spectroscopic and photometric constraints, the only viable explanation

for the main sequence splitting appears to be Helium enrichment, up to

an astonishingly high Y=0.4. The conditions under which certain

globulars experience the formation of multiple stellar generations

remain mysterious, and even more so the helium-enrichment phenomenon.

Such an enrichment has important implications for chemical-enrichment,

star-formation, and stellar-evolution scenarios, in star clusters and

likely elsewhere. To properly constrain the multiple main sequence

phenomenon, it is important to determine its extent among GCs: is it

limited to Omega Cen and NGC2808, or is it more common? We propose deep

WFC3 optical/IR imaging of NGC 6388 and 6441, the two globular clusters

that are most likely to host multiple, helium-enriched populations. Our

simulations of WFC3 performance suggest that we will be able to detect

even the main sequence splittings caused by small He differences (Delta

Y <0.03).

WFC3/IR 11719

A Calibration Database for Stellar Models of Asymptotic Giant Branch

Stars

Studies of galaxy formation and evolution rely increasingly on the

interpretation and modeling of near-infrared observations. At these

wavelengths, the brightest stars are intermediate mass asymptotic giant

branch (AGB) stars. These stars can contribute nearly 50% of the

integrated luminosity at near infrared and even optical wavelengths,

particularly for the younger stellar populations characteristic of

high-redshift galaxies (z>1). AGB stars are also significant sources of

dust and heavy elements. Accurate modeling of AGB stars is therefore of

the utmost importance.

The primary limitation facing current models is the lack of useful

calibration data. Current models are tuned to match the properties of

the AGB population in the Magellanic Clouds, and thus have only been

calibrated in a very narrow range of sub-solar metallicities.

Preliminary observations already suggest that the models are

overestimating AGB lifetimes by factors of 2-3 at lower metallicities.

At higher (solar) metallicities, there are no appropriate observations

for calibrating the models.

We propose a WFC3/IR SNAP survey of nearby galaxies to create a large

database of AGB populations spanning the full range of metallicities and

star formation histories. Because of their intrinsically red colors and

dusty circumstellar envelopes, tracking the numbers and bolometric

fluxes of AGB stars requires the NIR observations we propose here. The

resulting observations of nearby galaxies with deep ACS imaging offer

the opportunity to obtain large (100-1000's) complete samples of AGB

stars at a single distance, in systems with well-constrained star

formation histories and metallicities.

FGS 11704

The Ages of Globular Clusters and the Population II Distance Scale

Globular clusters are the oldest objects in the universe whose age can

be accurately determined. The dominant error in globular cluster age

determinations is the uncertain Population II distance scale. We propose

to use FGS 1R to obtain parallaxes with an accuracy of 0.2

milliarcsecond for 9 main sequence stars with [Fe/H] < -1.5. This will

determine the absolute magnitude of these stars with accuracies of 0.04

to 0.06mag. This data will be used to determine the distance to 24

metal-poor globular clusters using main sequence fitting. These

distances (with errors of 0.05 mag) will be used to determine the ages

of globular clusters using the luminosity of the subgiant branch as an

age indicator. This will yield absolute ages with an accuracy of 5%,

about a factor of two improvement over current estimates. Coupled with

existing parallaxes for more metal-rich stars, we will be able to

accurately determine the age for globular clusters over a wide range of

metallicities in order to study the early formation history of the Milky

Way and provide an independent estimate of the age of the universe.

The Hipparcos database contains only 1 star with [Fe/H] < -1.4 and an

absolute magnitude error less than 0.18 mag which is suitable for use in

main sequence fitting. Previous attempts at main sequence fitting to

metal-poor globular clusters have had to rely on theoretical

calibrations of the color of the main sequence. Our HST parallax program

will remove this source of possible systematic error and yield distances

to metal-poor globular clusters which are significantly more accurate

than possible with the current parallax data. The HST parallax data will

have errors which are 10 times smaller than the current parallax data.

Using the HST parallaxes, we will obtain main sequence fitting distances

to 11 globular clusters which contain over 500 RR Lyrae stars. This will

allow us to calibrate the absolute magnitude of RR Lyrae stars, a

commonly used Population II distance indicator.

COS/NUV/FUV 11698

The Structure and Dynamics of Virgo's Multi-Phase Intracluster Medium

The dynamical flows of the intracluster medium (ICM) are largely

unknown. We propose to map the spatial and kinematic distribution of the

warm ICM of the nearby Virgo cluster using the Cosmic Origins

Spectrograph. 15 sightlines at a range of impact parameters within the

virial radius of the cluster (0.2 - 1.7 Mpc) will be probed for

Lyman-alpha absorption and the data compared to blind HI, dust and x-ray

surveys to create a multi-phase map of the cluster's ICM. Absorption

line sightlines are commonly 40-100 kpc from a galaxy, allowing the flow

of baryons between galaxies and the ICM to be assessed. The velocity

distribution of the absorbers will be directly compared to simulations

and used to constrain the turbulent motions of the ICM. This proposal

will result in the first map of a cluster's warm ICM and provide

important tests for our theoretical understanding of cluster formation

and the treatment of gas cooling in cosmological simulations.

ACS/WFC3 11669

The Origins of Short Gamma-Ray Bursts

During the past decade extraordinary progress has been made in

determining the origin of long- duration gamma-ray bursts. It has been

conclusively shown that these objects derive from the deaths of massive

stars. Nonetheless, the origin of their observational cousins,

short-duration gamma-ray bursts (SGRBs) remains a mystery. While SGRBs

are widely thought to result from the inspiral of compact binaries, this

is a conjecture. SGRBs have been found in elliptical galaxies, Abell

Clusters, star-forming dwarfs and even an edge-on spiral. Whether they

primarily result from an old population, a young population, or rapid

evolution of binaries in globular clusters remains open.

Here we propose to employ two related sets of observations which may

dramatically advance our understanding of short bursts. The first is a

variant of a technique that we pioneered and used to great effect in

elucidating the origins of long-duration bursts. We will examine a

statistical sample of hosts and measure the degree to which SGRB

locations trace the red or blue light of their hosts, and thus old or

young stellar populations. This will allow us to study the demographics

of the SGRB population in a manner largely free of the distance

dependent selection effects which have so far bedeviled this field. In

the second line of attack we will use two targets of opportunity to

obtain extremely precise positions of up to two nearby bursts -- one on

a star-forming galaxy and the other on a elliptical. Observation of the

star-formation galaxy could link at least some bursts directly to a

young population; however, a discovery in later images of a globular

cluster at the site of the explosion in an elliptical would provide

revolutionary evidence that SGRBs are formed from compact binaries.

WFC3/UVIS/IR 11644

A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into

the Formation of the Outer Solar System

The eight planets overwhelmingly dominate the solar system by mass, but

their small numbers, coupled with their stochastic pasts, make it

impossible to construct a unique formation history from the dynamical or

compositional characteristics of them alone. In contrast, the huge

numbers of small bodies scattered throughout and even beyond the

planets, while insignificant by mass, provide an almost unlimited number

of probes of the statistical conditions, history, and interactions in

the solar system. To date, attempts to understand the formation and

evolution of the Kuiper Belt have largely been dynamical simulations

where a hypothesized starting condition is evolved under the

gravitational influence of the early giant planets and an attempt is

made to reproduce the current observed populations. With little

compositional information known for the real Kuiper Belt, the test

particles in the simulation are free to have any formation location and

history as long as they end at the correct point. Allowing compositional

information to guide and constrain the formation, thermal, and

collisional histories of these objects would add an entire new dimension

to our understanding of the evolution of the outer solar system. While

ground based compositional studies have hit their flux limits already

with only a few objects sampled, we propose to exploit the new

capabilities of WFC3 to perform the first ever large-scale

dynamical-compositional study of Kuiper Belt Objects (KBOs) and their

progeny to study the chemical, dynamical, and collisional history of the

region of the giant planets. The sensitivity of the WFC3 observations

will allow us to go up to two magnitudes deeper than our ground based

studies, allowing us the capability of optimally selecting a target list

for a large survey rather than simply taking the few objects that can be

measured, as we have had to do to date. We have carefully constructed a

sample of 120 objects which provides both overall breadth, for a general

understanding of these objects, plus a large enough number of objects in

the individual dynamical subclass to allow detailed comparison between

and within these groups. These objects will likely define the core

Kuiper Belt compositional sample for years to come. While we have many

specific results anticipated to come from this survey, as with any

project where the field is rich, our current knowledge level is low, and

a new instrument suddenly appears which can exploit vastly larger

segments of the population, the potential for discovery -- both

anticipated and not -- is extraordinary.

WFC3/UV/ACS/WFC 11636

First Resolved Imaging of Escaping Lyman Continuum

The emission from star-forming galaxies appears to be responsible for

reionization of the universe at z > 6. However, the models that attempt

to describe the detailed impact of high-redshift galaxies on the

surrounding inter-galactic medium (IGM) are strongly dependent upon

several uncertain parameters. Perhaps the most uncertain is the fraction

of HI-ionizing photons produced by young stars that escape into the IGM.

Most attempts to measure this "escape fraction" have produced null

results. Recently, a small subset of z~3 Lyman Break Galaxies (LBGs) has

been found exhibiting large escape fractions. It remains unclear

however, what differentiates them from other LBGs. Several models

attempt to explain how such a large fraction of ionizing continuum can

escape through the HI and dust in the ISM (eg. "chimneys" created by SNe

winds, globular cluster formation, etc.), each producing unique

signatures which can be observed with resolved imaging of the escaping

Lyman continuum. To date, there are only six LBGs with individual

detections of escaping Lyman continuum at any redshift. We propose a

single deep, high resolution WFC3/UVIS image of the ionizing continuum

(F336W) and the rest-frame UV/optical (F606W/F814W/F160W) of five of

these six LBGs with large escape fractions. These LBGs have a high

surface density and large escape fractions, and lie at the optimal

redshift for Lyman continuum imaging with UVIS filters, making our

sample especially suitable for follow-up. With these data we will

discern the mechanisms responsible for producing large escape fractions,

and therefore gain insight into the process of reionization.

STIS/CCD 11634

Probing the Collimation of Pristine Post-AGB Jets with STIS

The shaping of planetary and protoplanetary nebulae (PNe and PPNe) is

probably the most exciting yet least understood problem in the late

evolution of ~1-8 solar mass stars. An increasing number of astronomers

believe that fast jet-like winds ejected in the PPN phase are

responsible for carving out the diverse shapes in the dense envelopes of

the Asymptotic Giant Branch (AGB) stars. To date, the properties of

these post-AGB jets have not been characterized and, indeed, their

launching/collimation mechanism is still subject to controversial

debate. This is due to the lack of the direct observations probing the

spatio-kinematic structure of post-AGB winds in the stellar vicinity

(~10e16cm), which is only possible with HST+STIS.

Recently, STIS observations have allowed us for the first time the

DIRECT study of the structure and kinematics of the elusive post-AGB

winds in one PPN, He3-1475 (Sanchez Contreras & Sahai 2001). Those winds

have been discovered through H-alpha blue-shifted absorption features in

the inner 0.3"-0.7" of the nebula. These STIS observations have revealed

an ultra-fast collimated outflow relatively unaffected by the

interaction with the AGB wind that is totally hidden in ground-based

spectroscopic observations and HST images. The discovery of the pristine

ultra-fast (~2300km/s) jet in He3-1475 is the first observational

confirmation of the presence of collimated outflows as close as ~10e16cm

from the central star. Most importantly, the spatio-kinematic structure

of the ultra-fast jet clearly rules out hydrodynamical collimation alone

and favors magnetic wind collimation. Therefore, STIS observations

provide a unique method of probing the structure, kinematics, and

collimation mechanism of the elusive post-AGB winds. We now propose

similar observations for a sample of bipolar PPNe with ongoing post-AGB

ejections in order to investigate the frequency of jets like those in

He3-1475 in other PPNe and elucidate their nature and collimation

mechanism. The observational characterization of these winds is

indispensable for understanding this violent and important phase of

post-AGB evolution.

WFC3/IR 11631

Binary Brown Dwarfs and the L/T Transition

Brown dwarfs traverse spectral types M, L and T as their atmospheric

structure evolves and they cool into oblivion. This SNAPSHOT program

will obtain WFC3-IR images of 45 nearby late-L and early-T dwarfs to

investigate the nature of the L/T transition. Recent analyses have

suggested that a substantial proportion of late-L and early-T dwarfs are

binaries, comprised of an L dwarf primary and T dwarf secondary. WFC3-IR

observations will let us quantify this suggestion by expanding coverage

to a much larger sample, and permitting comparison of the L/T binary

fraction against ‘normal’ ultracool dwarfs. Only eight L/T binaries are

currently known, including several that are poorly resolved: we

anticipate at least doubling the number of resolved systems. The

photometric characteristics of additional resolved systems will be

crucial to constraining theoretical models of these late-type ultracool

dwarfs. Finally, our data will also be eminently suited to searching for

extremely low luminosity companions, potentially even reaching the Y

dwarf regime.

WFC3/UVIS 11628

Globular Cluster Candidates for Hosting a Central Black Hole

We are continuing our study of the dynamical properties of globular

clusters and we propose to obtain surface brightness profiles for high

concentration clusters. Our results to date show that the distribution

of central surface brightness slopes do not conform to standard models.

This has important implications for how they form and evolve, and

suggest the possible presence of central intermediate-mass black holes.

From our previous archival proposals (AR-9542 and AR- 10315), we find

that many high concentration globular clusters do not have flat cores or

steep central cusps, instead they show weak cusps. Numerical simulations

suggest that clusters with weak cusps may harbor intermediate-mass black

holes and we have one confirmation of this connection with omega

Centauri. This cluster shows a shallow cusp in its surface brightness

profile, while kinematical measurements suggest the presence of a black

hole in its center. Our goal is to extend these studies to a sample

containing 85% of the Galactic globular clusters with concentrations

higher than 1.7 and look for objects departing from isothermal behavior.

The ACS globular cluster survey (GO-10775) provides enough objects to

have an excellent coverage of a wide range of galactic clusters, but it

contains only a couple of the ones with high concentration. The proposed

sample consists of clusters whose light profile can only be adequately

measured from space-based imaging. This would take us close to

completeness for the high concentration cases and therefore provide a

more complete list of candidates for containing a central black hole.

The dataset will also be combined with our existing kinematic

measurements and enhanced with future kinematic studies to perform

detailed dynamical modeling.

ACS/WFC/WFC3/IR 11624

Black Hole Superkicks: Lmaging the Site of a Gravitational Wave Recoil

Event

Recent numerical relativity simulations of coalescing, binary

supermassive black holes (SMBHs) predict kick velocities as large as

several thousand km/s due to anisotropic emission of gravitational

waves. We have recently discovered the best candidate to date for such a

recoiling SMBH, the quasar SDSS0927+2943. It shows an exceptional

optical emission-line spectrum with two sets of emission lines; one set

of very narrow emission lines, and a second set of broad Balmer and

broad high-ionization forbidden lines which are blueshifted by 2650 km/s

relative to the narrow emission lines. This is the predicted

spectroscopic signature of a SMBH recoiling from the core of its host

galaxy, carrying with it the broad-line gas while leaving behind the

bulk of the narrow-line gas. We apply for HST imaging in two filters for

two orbits each in order to confirm the recoil model by detecting the

host galaxy of the SMBH and measuring the angular offset of the

recoiling SMBH from the host galaxy core; and determining, if possible,

the morphology of the host galaxy in order to constrain its merger

history. Confirmation of the SMBH ejection model for SDSSJ0927+2943 with

HST will show decisively that kicks large enough to remove SMBHs

completely from their host galaxies do occur, a result that would have

profound implications for models of SMBH evolution and galaxy assembly

and for numerical relativity.

WFC3/UV 11602

High-resolution imaging of three new UV-bright lensed arcs

We have identified and spectroscopically confirmed three new strongly

lensed, UV-bright star-forming galaxies at z ~ 2 that are similar to the

well-studied gravitationally lensed Lyman Break Galaxy (LBG)

MS1512-cB58, and are of comparable brightness to the ''8 O'Clock Arc''

(Allam et al. 2007) and ''Clone'' systems (Lin et al. 2008). The 8

O'Clock Arc and Clone have already been awarded 20 orbits for deep WFPC2

and NICMOS imaging in five bands (HST cycle 16, Program 11167, PI:

Allam). Adding these three recently discovered objects thus completes a

unique set of the brightest known strongly lensed galaxies at z ~ 2,

with magnitudes of r~20-21, and they provide a new window into the

detailed study of the properties of high redshift galaxies. We propose

21 orbits for deep WFC3 imaging in five bands (F475W, F606W, F814W,

F110W, and F160W) in order to construct detailed lensing models, to

probe the mass and light profiles of the lensing galaxies and their

environments, and to constrain the spectral energy distributions, star

formation histories, and morphologies of the lensed galaxies.

STIS/CCD/MA2 11568

A SNAPSHOT Survey of the Local Interstellar Medium: New NUV Observations

of Stars with Archived FUV Observations

We propose to obtain high-resolution STIS E230H SNAP observations of

MgII and FeII interstellar absorption lines toward stars within 100

parsecs that already have moderate or high-resolution far-UV (FUV),

900-1700 A, observations available in the MAST Archive. Fundamental

properties, such as temperature, turbulence, ionization, abundances, and

depletions of gas in the local interstellar medium (LISM) can be

measured by coupling such observations. Due to the wide spectral range

of STIS, observations to study nearby stars also contain important data

about the LISM embedded within their spectra. However, unlocking this

information from the intrinsically broad and often saturated FUV

absorption lines of low-mass ions, (DI, CII, NI, OI), requires first

understanding the kinematic structure of the gas along the line of

sight. This can be achieved with high resolution spectra of high-mass

ions, (FeII, MgII), which have narrow absorption lines, and can resolve

each individual velocity component (interstellar cloud). By obtaining

short (~10 minute) E230H observations of FeII and MgII, for stars that

already have moderate or high- resolution FUV spectra, we can increase

the sample of LISM measurements, and thereby expand our knowledge of the

physical properties of the gas in our galactic neighborhood. STIS is the

only instrument capable of obtaining the required high resolution data

now or in the foreseeable future.