Search

We have imaged GM Aur with HST, detected its disk in scattered light at 1400A and 1650A, and compared these with observations at 3300A, 5550A, 1.1 microns, and 1.6 microns. The scattered light increases at shorter wavelengths. The radial surface brightness profile at 3300A shows no evidence of the 24AU radius cavity that has been previously observed in sub-mm observations. Comparison with dust grain opacity models indicates the surface of the entire disk is populated with sub-micron grains. We have compiled an SED from 0.1 microns to 1 mm, and used it to constrain a model of the star+disk system that includes the sub-mm cavity using the Monte Carlo Radiative Transfer code by Barbara Whitney. The best-fit model image indicates that the cavity should be detectable in the F330W bandpass if the cavity has been cleared of both large and small dust grains, but we do not detect it. The lack of an observed cavity can be explained by the presence of sub-microns grains interior to the sub-mm cavity wall. We suggest one explanation for this which could be due to a planet of mass, 40 pages, 11 figures, 4 tables, accepted to ApJ

Wetracethediskof HD169142(A8Ve)from0.57 00 to1.4 00 (� 80Y200AUprojecteddistance)in1.1 � mscattered light with HST NICMOS coronagraphy. The azimuthally symmetric disk has a peak azimuthally medianed surface brightness (SB) of � 5 mJy arcsec � 2 at 0.57 00 from the star, and drops /r � 3 . This radial SB profile is consistent with the presence of spatially resolved PAH emission and a Meeus group I IR SED only if the inner disk is either substantially flatter than the outer disk or partially devoid of material. Analysis of new HSTACS FUVimagery in tandemwitharchivalIUEdataindicates ˙ Macc � 10 � 9 Myr � 1 .Weestimatetheageof HD169142tobe6 þ6 � 3 Myrby identifying 2MASS 18242929� 2946559, located 9.3 00 to the southwest, as a 130 mas separation weak-line T Tauri binary that is comoving with HD 169142 at the 4 � confidence level. We find no evidence for any additional stellar companion in either the ACS or Chandra ACIS-S data at r � 1 00 . HD 169142 has previously been interpreted as a slowly rotating, chemically peculiar star. However, by combining the disk inclination andv sini from the literature, we find that the star hasvequatorial � 240 km s � 1 , making it a rapid rotator, similar to Altair or Vega. The UV data for HD 169142 are consistent with gravity darkening, while the X-ray luminosity and spectrum resembles early F stars at the age of thePictoris moving group, rather than mid-A stars. In this context, spectral features previously interpreted as evidence for chemical peculiarity are more likely to reflect the presence of a strong photospheric latitudinal temperature gradient. With such a gradient, HD 169142 should closely resemble Vega at the epoch of central disk clearing. Subject headings: binaries: visual — planetary systems: protoplanetary disks — stars: individual (2MASS 18242929� 2946559, HD 22128, HD 36112, HD 142666, HD 169142, HD 220750) — stars: low-mass, brown dwarfs — stars: preYmain-sequence

We present narrow-band images of the Red Rectangle (RR) nebula which reveal the distinct morphologies of this intriguing nebula in different optical emission bands. The morphology of the RR nebula in blue luminescence (BL) and extended red emission (ERE) are almost mutually exclusive. We also present the optical detection of the circum-binary disk of the RR in the light of the BL. The total intensities from the two optical band emissions (BL and ERE) when summed over the nebula are of comparable magnitude. Their spatial distributions with respect to the embedded illumination sources lead us to suggest that they may be attributed to different ionization stages of the same family of carriers., Accepted to ApJ

We present Spitzer Space Telescope observations of the z=2.38 lya-emitter over-density associated with galaxy cluster J2143-4423, the largest known structure (110 Mpc) above z=2. We imaged 22 of the 37 known lya-emitters within the filament-like structure, using the MIPS 24um band. We detected 6 of the lya-emitters, including 3 of the 4 clouds of extended (>50 kpc) lyman alpha emission, also known as Lya Blobs. Conversion from rest-wavelength 7um to total far-infrared luminosity using locally derived correlations suggests all the detected sources are in the class of ULIRGs, with some reaching Hyper-LIRG energies. Lya blobs frequently show evidence for interaction, either in HST imaging, or the proximity of multiple MIPS sources within the Lya cloud. This connection suggests that interaction or even mergers may be related to the production of Lya blobs. A connection to mergers does not in itself help explain the origin of the Lya blobs, as most of the suggested mechanisms for creating Lya blobs (starbursts, AGN, cooling flows) could also be associated with galaxy interactions.

We present high contrast images of the hydrogen white dwarf G 29-38 taken in the near infrared with the Hubble Space Telescope and the Gemini North Telescope as part of a high contrast imaging search for substellar objects in orbit around nearby white dwarfs. We review the current limits on planetary companions for G29-38, the only nearby white dwarf with an infrared excess due to a dust disk. We add our recent observations to these limits to produce extremely tight constraints on the types of possible companions that could be present. No objects $>$ 6 M$_{Jup}$ are detected in our data at projected separations $>$ 12 AU, and no objects $>$ 16 M$_{Jup}$ are detected for separations from 3 to 12 AU, assuming a total system age of 1 Gyr. Limits for companions at separations $, Comment: 20 pages, 4 figures, Accepted to ApJ

We present HST spectroscopy of the nucleus of M31 obtained with STIS. Spectra taken around the CaT lines at 8500 see only the red giants in the double bright- ness peaks P1 and P2. In contrast, spectra taken at 3600-5100 A are sensitive to the tiny blue nucleus embedded in P2, the lower surface brightness red nucleus. P2 has a K-type spectrum, but the embedded blue nucleus has an A-type spectrum with strong Balmer absorption lines. Given the small likelihood for stellar collisions, a 200 Myr old starburst appears to be the most plausible origin of the blue nucleus. In stellar population, size, and velocity dispersion, the blue nucleus is so different from P1 and P2 that we call it P3. The line-of-sight velocity distributions of the red stars in P1+P2 strengthen the support for Tremaine s eccentric disk model. The kinematics of P3 is consistent with a circular stellar disk in Keplerian rotation around a super-massive black hole with M_bh = 1.4 x 10^8 M_sun. The P3 and the P1+P2 disks rotate in the same sense and are almost coplanar. The observed velocity dispersion of P3 is due to blurred rotation and has a maximum value of sigma = 1183+-201 km/s. The observed peak rotation velocity of P3 is V = 618+-81 km/s at radius 0.05" = 0.19 pc corresponding to a circular rotation velocity at this radius of ~1700 km/s. Any dark star cluster alternative to a black hole must have a half-mass radius, Astrophysical Journal, Sep 20, 2005, 21 pages including 20 figures

STIS white-light coronagraphic imaging has been carried out for 14 nearby, lightly reddened Herbig Ae stars, providingdataontheenvironmentsanddisksassociatedwiththesestars.Nodisksaredetectedinourdatawhenthe Herbig Ae starisaccompaniedbya stellarcompanion atr � 2 00 .Wefindthattheopticalvisibilityofprotoplanetary disks associated with Herbig Ae stars at r � 50 70 AU from the star is correlated with the strength of the mid-IR PAH features, particularly 6.2 � m. These features, like the FUV fluorescent H2 emission, trace the presence of material sufficiently far above the disk midplane that it is directly illuminated by the star’s FUV radiation. In contrast, measures of the bulk properties of the disk, including ongoing accretion activity, mass, and the submillimeter slope of the SED, do not correlate with the surface brightness of the optical nebulosity. Modelers have interpreted the appearance of the IR SED and the presence of emission from warm silicate grains at 10 � ma s a measure of geometrical shadowing by material in the disk near the dust sublimation radius of 0.5 AU. Geometrical shadowing sufficient to render a disk dark to distances as large as 500 AU from a star would require that the star be optically visible only if viewed essentially pole-on, in disagreement with our program star system inclinations. Rather than invoking shadowing to account for the optically dark disks, the correlation of the STIS detections with PAHemissionfeaturessuggestsacorrelationwithdiskflaringandananticorrelationwiththedegreeofdustsettling toward the midplane. If this correlation continues to lower levels, the STIS data suggest that improvements in coronagraph performance that suppress the residual scattered and diffracted stellar light by an additional factor of � 10 should render the majority of disks associated with nearby Herbig Ae stars detectable. Subject headingg infrared: stars — ISM: Herbig-Haro objects — ISM: jets and outflows — stars: pre–main-sequence

Results from a concerted Hubble Space Telescope (HST) survey of nearby white dwarfs for substellar objects is presented. A total of 7 DAZ white dwarfs with distances of $$ 18 M$_{Jup}$ for all of the targets. The lack of significant near infrared excesses for our targets limits any kind of unresolved companions present to be substellar. In light of these results we make several comments on the possibility of determining the origin of white dwarfs with metals in their atmospheres., Comment: 11 pages, 7 figures, emulateapj, revisions to figures and text, to appear in September AJ

Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A point-like, soft (kT~0.5 keV), emission-line source is detected at the location of the star with an X-ray luminosity of 4.0e29 erg/s. In addition, faint emission along the direction of a previously-detected Ly-alpha-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically-thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least ~100 G and perhaps as high as several kG. HD 163296 joins the T Tauri star TW Hya in being the only examples known to date of pre-main-sequence stars whose quiescent X-ray emission appears to be completely dominated by accretion., Comment: 7 pages, to be published in ApJ, 20 June 2005

The inner 100 AU of HD 100546 is studied via far-ultraviolet long-slit spectroscopy with the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS). The star is surrounded by reflection nebulosity, which can be traced 100 AU in the continuum, and by emission from H I Lyα, N I, Si II, and fluorescent H2 transitions. The Lyα emission can be traced up to 200 AU along the system semimajor axis and 300 AU along the semiminor axis. The radial surface brightness profile and the presence of both reflection nebulosity and molecular gas suggest that we have detected the flared surface of the disk predicted from analysis of the IR spectral energy distribution. When corrected for the r-2 falloff in illumination from the Herbig Be star, the reflection nebulosity, neutral atomic gas, and H2 emission all reveal the presence of a central cavity extending 013 ± 0025 (13 AU) from the star, more than 20 times larger in radius than would be expected from dust sublimation alone. The reflection nebulosity within the cavity is centered on a location 005 (5 AU) to the southeast of the star along the system semimajor axis. The pericenter asymmetry in the cavity is inconsistent with cavity formation by the combined effects of ice sublimation, radiation pressure blowout on small grains, or other disk chemistry that should produce azimuthally symmetric features. The STIS data are also consistent with a current accretion rate onto the Herbig Be star no higher than a few times 10-9 M☉ yr-1, an order of magnitude lower than seen in 5-8 Myr old Herbig Ae stars. The low accretion rate, large cavity, pericenter asymmetry, and deficit of warm dust grain emission observed over 2-8 μm are all consistent with dynamical sculpting of the disk by one or more bodies within the disk. An upper limit to the flux from any chromospherically active, low-mass companion is a factor of 5-10 fainter than AU Mic (M1 Ve; t = 12 Myr) at the distance of HD 100546. This upper limit firmly excludes a low-mass stellar companion within the cavity but does not exclude a less active and/or luminous brown dwarf. The absence of similar central clearing in younger Herbig Ae stars suggests that any companion must become externally detectable late in the evolution of the disk, favoring a giant planet as the source of the structure in the HD 100546 disk.

In Paper 1 of this series we identified an 80 co-moving Mpc filament of candidate Lyman-alpha emitting galaxies at redshift 2.38. In this paper we present spectroscopy of the 37 galaxy candidates. Our spectroscopy reached a surface brightness limit of 5.0E-17 erg/cm^2/s/arcsec^2. Of the 14 candidates down to this limit, 12 were confirmed to be Lyman-alpha emitting galaxies at the filament redshift. We also obtained spectral confirmation for six of the lower surface brightness candidates, all of which also lay at the filament redshift. In addition, we identify a foreground cluster of QSOs at z=1.65.

The STIS/CCD camera on the {\em Hubble Space Telescope (HST)} was used to take deep optical images near the K2V main-sequence star $\epsilon$ Eridani in an attempt to find an optical counterpart of the dust ring previously imaged by sub-mm observations. Upper limits for the optical brightness of the dust ring are determined and discussed in the context of the scattered starlight expected from plausible dust models. We find that, even if the dust is smoothly distributed in symmetrical rings, the optical surface brightness of the dust, as measured with the {\em HST}/STIS CCD clear aperture at 55 AU from the star, cannot be brighter than about 25 STMAG/"$^2$. This upper limit excludes some solid grain models for the dust ring that can fit the IR and sub-mm data. Magnitudes and positions for $\approx $59 discrete objects between 12.5" to 58" from $\epsilon$ Eri are reported. Most if not all of these objects are likely to be background stars and galaxies., Comment: Revision corrects author list

We present the detection of 34 Lyα emission-line galaxy candidates in a 80 × 80 × 60 comoving Mpc region surrounding the known z = 2.38 galaxy cluster J2143-4423. The space density of Lyα emitters is comparable to that found by Steidel et al. when targeting a cluster at redshift 3.09, which is a factor of 5.8 ± 2.5 greater than that found by field samples at similar redshifts. The distribution of these galaxy candidates contains several 5-10 Mpc scale voids. We compare our observations with mock catalogs derived from the VIRGO consortium ΛCDM n-body simulations. Fewer than 1% of the mock catalogs contain voids as large as we observe. Our observations thus tentatively suggest that the galaxy distribution at redshift 2.38 contains larger voids than predicted by current models. Three of the candidate galaxies and one previously discovered galaxy have the large luminosities and extended morphologies of "Lyα blobs."

The unfiltered Space Telescope Imaging Spectrograph (STIS) CCD in tandem with focal plane wedges and a Lyot stop provides a simple white‐light coronagraph with a bandpass of 0.2–1.0 μm, which has been used since late 1998 to image nebulosity around stars in the ranges \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $0.34\leq V\leq 14$ \end{document} and \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \use...

We report long-slit spectroscopic mapping of the η Carinae nebula obtained using the Space Telescope Imaging Spectrograph. The observations reveal the presence of a previously unknown bipolar emission nebula (roughly ±2'' along its major axis) embedded within the well-known and larger Homunculus Nebula. A preliminary analysis suggests that this embedded nebula may have originated from a minor eruption event circa 1890, 50 years after the formation of the larger Homunculus.

In the first 3 years of operation the Space Telescope Imaging Spectrograph (STIS) obtained slitless spectra of ~2500 fields in parallel to prime Hubble Space Telescope (HST) observations as part of the STIS parallel survey (SPS). The archive contains ~300 fields at high Galactic latitude ( > 30°) with spectroscopic exposure times greater than 3000 s. This sample contains 219 fields (excluding special regions and requiring a consistent grating angle) observed between 1997 June 6 and 2000 September 21, with a total survey area of ~160 arcmin2. At this depth, the SPS detects an average of one emission-line galaxy per three fields. We present the analysis of these data and the identification of 131 low- to intermediate-redshift galaxies detected by optical emission lines. The sample contains 78 objects with emission lines that we infer to be redshifted [O II] λ3727 emission at 0.43 < z < 1.7. The comoving number density of these objects is comparable to that of Hα-emitting galaxies in the NICMOS parallel observations. One quasar and three probable Seyfert galaxies are detected. Many of the emission-line objects show morphologies suggestive of mergers or interactions. The reduced data are available upon request from the authors.

(Abridged) We present a new high-resolution (7 km/s FWHM) echelle spectrum of 3C 351 obtained with STIS. 3C 351 lies behind the low-latitude edge of high-velocity cloud Complex C, and the new spectrum provides accurate measurements of O I, Si II, Al II, Fe II, and Si III absorption lines at the velocity of the HVC. We use collisional and photoionization models to derive ionization corrections; in both models we find that the overall metallicity Z = 0.1 - 0.3 Z_{solar} in Complex C, but nitrogen must be underabundant. The iron abundance indicates that Complex C contains very little dust. The absorbing gas probably is not gravitationally confined. The gas could be pressure-confined by an external medium, but alternatively we may be viewing the leading edge of the HVC, which is ablating and dissipating as it plunges into the Milky Way. O VI column densities observed with FUSE toward nine QSOs/AGNs behind Complex C support this conclusion: N(O VI) is highest near 3C 351, and the O VI/H I ratio increases substantially with decreasing latitude, suggesting that the lower-latitude portion of the cloud is interacting more vigorously with the Galaxy. The other sight lines through Complex C show some dispersion in metallicity, but with the current uncertainties, the measurements are consistent with a constant metallicity throughout the HVC. However, all of the Complex C sight lines require significant nitrogen underabundances. Finally, we compare the 3C 351 sight line to the sight line to the nearby QSO H1821+643 to search for evidence of outflowing Galactic fountain gas that could be mixing with Complex C. We find that the intermediate-velocity gas detected toward 3C 351 and H1821+643 has a higher metallicity and may well be a fountain/chimney outflow from the Perseus spiral arm., Submitted to AJ. Figures 1-4 compressed for astro-ph; better quality figures are available at http://astro.princeton.edu/~tripp/astro/qualitypreps/complexc.ps.gz

Using what is known about the physical and chemical structure of the CCD detector on the Space Telescope Imaging Spectrograph (STIS) and over 50 calibration images taken with different wavelength mappings onto the detector, we have devised a model function that allows us to predict the fringing of any spectral image taken with the STIS CCD. This function is especially useful for spectra taken without a slit with the G750L grating. The STIS parallel observing program uses this “slitless spectroscopy” mode extensively. The arbitrary mapping of wavelength versus position that results from each source's chance position in the field renders direct calibration of the fringe amplitudes in this mode impossible. However, we find that correcting observed data using our semiempirical fringing model produces a substantial reduction in the fringe amplitudes. Tests using the flux calibration white dwarf standard G191‐B2B show that we can reduce the fringe amplitude in the 9000–10000 A region from about 20% pea...

Using high S/N STIS echelle spectra (FWHM=7 km/s) of 3C 273, we constrain the metallicities of two Lya clouds in the vicinity of the Virgo cluster. We detect C II, Si II, and Si III absorption lines in the Lya absorber at z = 0.00530. Previous observations with FUSE have revealed Ly beta - Ly theta lines at this redshift, thereby accurately constraining N(H I). We model the ionization of the gas and derive [C/H] = -1.2^{+0.3}_{-0.2}, [Si/C] = 0.2+/-0.1, and log n_{H} = -2.8+/-0.3. The model implies a small absorber thickness, ~70 pc, and thermal pressure p/k ~ 40 cm^{-3} K. It is most likely that the absorber is pressure confined by an external medium because gravitational confinement would require a very high ratio of dark matter to baryonic matter. Based on Milky Way sight lines in which carbon and silicon abundances have been reliably measured in the same interstellar cloud (including new measurements presented herein), we argue that the overabundance of Si relative to C is not due to dust depletion. Instead, this probably indicates that the gas has been predominately enriched by Type II supernovae. Such enrichment is most plausibly provided by an unbound galactic wind, given the absence of galaxies within a projected distance of 100 kpc and the presence of galaxies capable of driving a wind at larger distances. We also constrain the metallicity and physical conditions of the Virgo absorber at z = 0.00337 based on detections of O VI and H I and an upper limit on C IV. If this absorber is collisionally ionized, the O VI/C IV limit requires T > 10^{5.3} K. For either collisional ionization or photoionization, we find that [O/H] > -2.0 at z = 0.00337.

We present near-IR (NIR) and far-UV observations of the pre-transitional (gapped) disk in HD 169142 using NASA's Infrared Telescope Facility and Hubble Space Telescope. The combination of our data along with existing data sets into the broadband spectral energy distribution reveals variability of up to 45% between (is) approximately1.5-10 micrometers over a maximum timescale of 10 yr. All observations known to us separate into two distinct states corresponding to a high near-IR state in the pre-2000 epoch and a low state in the post-2000 epoch, indicating activity within the (is) approximately less than 1AU region of the disk. Through analysis of the Pa beta and Br gamma lines in our data we derive a mass accretion rate in 2013 May of M (is) approx. = (1.5-2.7) 10(exp -9) solar mass yr(exp -1).We present a theoretical modeling analysis of the disk in HD 169142 using Monte-Carlo radiative transfer simulation software to explore the conditions and perhaps signs of planetary formation in our collection of 24 yr of observations. We find that shifting the outer edge (r (is) approx. = 0.3AU) of the inner disk by 0.05AU toward the star (in simulation of accretion and/or sculpting by forming planets) successfully reproduces the shift in NIR flux. We establish that the (is) approximately 40-70AU dark ring imaged in the NIR by Quanz et al. and Momose et al. and at 7 mm by Osorio et al. may be reproduced with a 30% scaled density profile throughout the region, strengthening the link to this structure being dynamically cleared by one or more planetary mass bodies.

Establishing improved spectrophotometric standards is important for a broad range of missions and is relevant to many astrophysical problems. ACCESS, Absolute Color Calibration Experiment for Standard Stars", is a series of rocket-borne sub-orbital missions and ground-based experiments designed to enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35 - 1.7μm bandpass. This paper describes the payload status, sub-system testing, and data transfer for the ACCESS instrument.

Coronagraphic imaging of the nearest Herbig Be star with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope, Ks (2.15 ?m) imaging with ADONIS at the 3.6 m telescope at La Silla, and mid-infrared imaging with OSCIR using the 4 m Blanco Telescope at Cerro Tololo Inter-American Observatory confirm the detection of the disk reported by Pantin et al. and map the disk out to 5'' (~515 AU) in the optical and at Ks. While the source is unresolved at 10 and 18 ?m, it can be traced to 15 at 11.7 ?m. We confirm the change in the radial dependence of the disk surface brightness near 27 seen at 1.6 ?m by Augereau et al. at Ks. No such break in the power law is seen in the optical. The STIS data reveal spiral dark lane structure, making HD 100546 the third near?zero-age main-sequence Herbig Ae/Be star with structure more than 100 AU from the star. We also optically detect a low surface brightness envelope extending 10'' (1000 AU) from the star, in addition to nebulosity, which is probably associated with DC 292.6-7.9. The survival of the envelope through essentially the entire pre?main-sequence lifetime of the star, coupled with the absence of physical companions within 1500 AU of the star, suggests that envelope lifetimes owe more to the star-forming environment than to mass-loss activity from the Herbig Ae/Be star.

We present far-ultraviolet spectroscopy of the cores of the massive cooling flow clusters Abell 1795 and 2597 obtained with FUSE. As the intracluster gas cools through 3x10^5 K, it should emit strongly in the OVI 1032,1038 resonance lines. We report the detection of OVI 1032 emission in A2597, with a line flux of 1.35 +/- 0.35x10^-15 erg/cm2/s, as well as detection of emission from CIII 977. A marginal detection of CIII 977 emission is also reported for A1795. These observations provide evidence for a direct link between the hot (10^7 K) cooling flow gas and the cool (10^4 K) gas in the optical emission line fients. Assuming simple cooling flow models, the OVI line flux in A2597 corresponds to a mass deposition rate of ~40 Msun/yr within the central 36 kpc. Emission from OVI 1032 was not detected in A1795, with an upper limit of 1.5x10^-15 erg/cm2/s, corresponding to a limit on the mass cooling flow rate of Mdot(28 kpc) < 28 Msun/yr. We have considered several explanations for the lack of detection of OVI emission in A1795 and the weaker than expected flux in A2597, including extinction by dust in the outer cluster, and quenching of thermal conduction by magnetic fields. We conclude that a turbulent mixing model, with some dust extinction, could explain our OVI results while also accounting for the puzzling lack of emission by FeXVII in cluster cooling flows., 19 pages, 5 postscript figures, accepted for publication in the Astrophysical Journal, June 14, 2001

We report on far-ultraviolet (FUV) observations of flares on the dM0e star AU Microscopii obtained on 1998 September 6 with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. The data consist of medium-resolution echelle spectra covering the wavelength region from 1170 to 1730 A with a spectral resolution of λ/Δλ = 45,800. The observations were obtained using the TIME-TAG observing mode in which the time and position of each detected photon is recorded. This allows a study of variability that is constrained only by counting statistics. During a total on-source time of 10,105 s, we observed numerous microflare bursts as well as four well-defined flare events. These flares lasted between 10 s and 3 minutes and were most easily detected in the FUV continuum and the Si IV and C IV resonance lines. Variations in both the cooler (e.g., Lyα, C II, O I) and hotter (O V, N V, Fe XXI) emission lines were much less pronounced. We examined the physical characteristics of the flare events, including the time history of the wavelength-integrated fluxes in the continuum and the various emission lines. In particular, we searched for, but did not find, evidence for increased emission in the red wing of the Lyα line, which would indicate the presence of moderately energetic proton beams. We integrated the emission over the entire time of major flare activity to investigate the average line and continuum properties of the time-averaged spectrum, including flows and turbulence as a function of temperature. We also considered the shape of the FUV continuum, which may actually be caused by the enhancement of numerous weak emission lines. Unfortunately, none of the events were strong enough to allow a detailed examination of line profiles as a function of time.

We present the first observations of a Herbig Ae star with a circumstellar disk by the Far Ultraviolet Spectroscopic Explorer (FUSE), as well as a simultaneous observation of the star obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS). The spectra of AB Aurigae show emission and absorption features arising from gasses that have a wide range in temperature, from hot OVI emission to cold molecular hydrogen and CO absorption. Emissions from the highly ionized species OVI and CIII present in the FUSE spectrum are redshifted, while absorption features arising from low-ionization species like OI, NI, and SiII are blueshifted and show characteristic stellar wind line-profiles. We find the total column density of molecular hydrogen toward AB Aur from the FUSE apectrum, N(H_2) = (6.8 +/- 0.5) x 10^19 cm^-2. The gas kinetic temperature of the molecular hydrogen derived from the ratio N(J=1)/N(J=0) is 65 +/- 4 K. The column density of the CO observed in the STIS spectrum is N(CO) = (7.1 +/- 0.5) x 10^13 cm^-2, giving a CO/H_2 ratio of (1.04 +/- 0.11) x 10^-6. We also use the STIS spectrum to find the column density of HI, permitting us to calculate the total column density of hydrogen atoms, the fractional abundance of H_2, and the gas-to-dust ratio.

We present the galaxy-galaxy angular correlations as a function of photometric redshift in a deep-wide galaxy survey centered on the Hubble Deep Field South. Images were obtained with the Big Throughput Camera on the Blanco 4m telescope at CTIO, of 1/2 square degree in broad-band uBVRI, reaching ~24th mag. Approximately 40,000 galaxies are detected in the survey. We determine photometric redshifts using galaxy template fitting to the photometry. Monte Carlo simulations show that redshifts from these data should be reliable out to z~1, where the 4000 Angstrom break shifts into the I-band. The inferred redshift distribution, n(z), shows good agreement with the distribution of galaxies measured in the HDF North and the Canada-France Redshift Survey. After assigning galaxies to redshift bins with width Delta_z=0.33, we determine the two point angular correlation function in each bin. We find that the amplitude of the correlation, A_w, drops across the three bins to redshift z~1. Simple epsilon models of clustering evolution fit this result, with the best agreement for epsilon=0. Hierarchical cold-dark-matter models best fit in a low density, Lambda-dominated universe., Comment: 41 preprint pages, including 12 figures; accepted for publication in ApJ

Coronagraphic imaging with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope reveals a ~450 AU radius circumstellar disk around the Herbig Ae star HD 163296. A broadband (0.2-1.0 μm) reflected light image shows the disk oriented at a position angle of 140° ± 5° and inclined to our line of sight by ~60° ± 5°. The disk includes an annulus of reduced scattering at 325 AU and exhibits a flat trend of surface brightness in to 180-122 AU (15-1''), consistent with a cleared central zone. For r ≥ 370 AU the disk surface brightness drops as r to the approximately -3.5 power. The disk cannot be traced beyond 450 AU in our data. The disk is accompanied by a chain of nebulosities at P.A.=425±35, compatible with detection of a Herbig-Haro flow. The HD 163296 disk most closely resembles the disk of HD 141569. As in the HD 141569 system, the dynamical effects of a planet may be necessary to explain the structure in the outer disk.

We report the detection in Lyα of a collimated, bipolar outflow (HH 409) associated with the 1.5-10 Myr old Herbig Ae star HD 163296. A blueshifted jet is visible in Lyα and Si III extending toward the southwest for at least 6'' (725 AU). The combination of low line-of-sight extinction and relative faintness of the central star near Lyα enables us to trace the jet to within an unprecedented 006 (7.3 AU) of HD 163296. The jet has a radial velocity of 335-380 km s-1, which is common for protostellar outflows. We also detected redshifted Lyα emission southwest of the star that may be due to infall or a poorly collimated wind component. If the age of the star is correct, then protostellar outflows may last up to 10 times longer than previously believed.

We investigate a very luminous Lyman-alpha emitting galaxy, associated with a z=2.3 damped absorption system in the spectrum of the QSO PHL 957. The galaxy was observed with the HST WFPC2, through a narrow filter (F410M) corresponding to rest-frame Lyman -alpha, for 41.2 ksec, with shorter exposures in F555W and F814W. The galaxy is resolved into a close (0.35 arcsec) pair of two components, CFgA and CFgB. The profile of CFgA is consistent with an exponential disk, but CFgB is closer to a bulge galaxy. Fr om the observed colours we estimate rest-frame Lyman-alpha equivalent widths of 151 Angstroms for CFgA and 33 for CFgB. From the F814W and F555W magnitudes we estimate rest-frame blue-band absolute magnitudes of -23.12 for CFgA and -23.24 for CFgB, signi ficantly brighter than local galaxies of the same size. CFgA shows a remarkable 3.9 magnitudes of surface brightness enhancement relative to local spirals, and we speculate that this may be the result of a very luminous starburst, triggered by the merger of the two components. The Lyman-alpha emission could be from a brief phase early in the starburst in which most of these photons can escape. We search for other z=2.3 galaxies with strong Lyman-alpha emission, selecting these by a colour F410M-F555W

We present candidate quasars from a multi-color (uBVRI + narrow-band) imaging survey of 1/2 square degree around the Hubble Deep Field - South. We identify 154 candidate quasars with B < 23 using color selection, consistent with previously measured QSO number counts if we assume a 60% selection efficiency. The narrow-band filter (NB) was centered at 3958 A to detect Ly-alpha at the redshift of J2233-6033, the HDF-S QSO. We confirm the presence of Ly-alpha nebulosity extending ~12'' around the HDF-S QSO, reported by Bergeron et al. (1999). We detect 10 point-like objects in emission through the NB filter. Of these, 7 satisfy our QSO color selection criteria. One of emission-line objects is a B~20 radio-quiet quasar at z=1.56, 6.7' from the line of sight to the HDF-S QSO and ~12'' from the western edge of the WFPC2 deep field., 13 pages and 6 figures, accepted for publication in ApJ

We discuss the utility of a low-resolution prism as a component of a multiobject spectrometer for NASA's proposed Next Generation Space Telescope (NGST). Low-resolution prism spectroscopy permits simultaneous observation of the 0.6-5 μm wavelength regime at R 50. Such data can take advantage of modern techniques in spectral energy distribution (SED) fitting to determine source redshifts, sometimes called "photometric redshifts." We compare simulated prism observations with filter imaging for this purpose with NGST. Low-resolution prism observations of galaxy SEDs provide a significant advantage over multifilter observations for any realistic observing strategy. For an ideal prism in sky background-limited observing, the prism has a signal-to-noise ratio advantage of the square root of the resolution over serial observations by filters with similar spatial and spectral resolution in equal integration time. For a realistic case the advantage is slightly less, and we have performed extensive simulations to quantify it. We define strict criteria for the recovery of input redshifts, such that to be considered a success, redshift residuals must be δz 30) objects at high redshift (z > 4), where the prism recovers 80% of redshifts, while the filters recover barely 35% to similar accuracy. The primary discovery space of NGST will be at the faintest magnitudes and the highest redshifts. Many important objects will be too faint for follow-up at higher spectral resolution, so prism observations are the optimal technique to study them. Prism observations also reduce the contamination of high-redshift samples by lower redshift interlopers.

We present new coronagraphic images of β Pictoris obtained with the Space Telescope Imaging Spectrograph (STIS) in 1997 September. The high-resolution images (01) clearly detect the circumstellar disk as close to the star as 075, corresponding to a projected radius of 15 AU. The images define the warp in the disk with greater precision and at closer radii to β Pic than do previous observations. They show that the warp can be modeled by the projection of two components: the main disk and a fainter component, which is inclined to the main component by 4°-5° and extends only as far as ≈4'' from the star. We interpret the main component as arising primarily in the outer disk and the tilted component as defining the inner region of the disk. The observed properties of the warped inner disk are inconsistent with a driving force from stellar radiation. However, warping induced by the gravitational potential of one or more planets is consistent with the data. Using models of planet-warped disks constructed by Larwood & Papaloizou, we derive possible masses of the perturbing object.

We present far-ultraviolet spectra of the Seyfert 1 galaxy Mrk 509 obtained in 1999 November with the Far Ultraviolet Spectroscopic Explorer (FUSE). Our data span the observed wavelength range 915-1185 A at a resolution of ~20 km/s. The spectrum shows a blue continuum, broad OVI 1032,1038 emission, and a broad CIII 977 emission line. Superposed on these emission components, we resolve associated absorption lines of OVI 1032,1038, CIII 977, and Lyman lines through Lzeta. Seven distinct kinematic components are present, spanning a velocity range of -440 to +170 km/s relative to the systemic velocity. The absorption is clustered in two groups, one centered at -370m km/s and another at the systemic velocity. The blue-shifted cluster may be associated with the extended line emission visible in deep images of Mrk 509 obtained by Phillips et al. Although several components appear to be saturated, they are not black at their centers. Partial covering or scattering permits ~7% of the broad-line or continuum flux to be unaffected by absorption. Of the multiple components, only one has the same ionization state and column density as highly ionized gas that produces the OVII and OVIII ionization edges in X-ray spectra of Mrk 509. This paper will appear in a special issue of Astrophysical Journal Letters devoted to the first scientific results from the FUSE mission.

Far-ultraviolet spectra were obtained of the active cool star AB Doradus (HD 36705) during the calibration and checkout period of the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. Observations in this early phase of the mission were taken at a resolving power of 12,000-15,000 (~20-25 km s-1) and covered the spectral range 905-1187 A. The integrated spectrum exhibits strong, rotationally broadened stellar emission from C III (λλ977, 1175) and O VI (λλ1032, 1037) and many weaker lines. Strong emission lines of C III and O VI exhibit broad wings. The C III λ977 profile shows blueshifted absorption at ~30 km s-1, and C II λ1036 absorption appears superposed on emission in the wing of O VI λ1037. Rotational modulation of C III and O VI is present, in harmony with its photometric variability. Flares were detected in the brightest lines, and subexposures were analyzed to examine flux and profile variations. Downflows that extend to 600 km s-1 during a flare are found in the O VI profiles. These early observations demonstrate that FUSE will be an exceptional instrument for studying chromospheres in cool stars.

We describe a moderate-resolution (20-25 km s-1) Far Ultraviolet Spectroscopic Explorer (FUSE) study of the low-redshift intergalactic medium. We report on studies of seven extragalactic sight lines and 12 Lyβ absorbers that correspond to Lyα lines detected by Hubble Space Telescope (HST)/Goddard High Resolution Spectrograph and Space Telescope Imaging Spectrograph. These absorbers appear to contain a significant fraction of the low-z baryons and were a major discovery of the HST spectrographs. Using FUSE data, with 40 mA (4 σ) Lyβ detection limits, we have employed the equivalent width ratio of Lyβ/Lyα, and occasionally higher Lyman lines, to determine the Doppler parameter b and accurate column densities N for moderately saturated lines. We detect Lyβ absorption corresponding to all Lyα lines with Wλ ≥ 200 mA. The Lyβ/Lyα ratios yield a preliminary distribution function of Doppler parameters, with mean b = 31.4 ± 7.4 km s-1 and median 28 km s-1, comparable to values at redshifts z = 2.0-2.5. If thermal, these b-values correspond to T ≈ 50,000 K, although the inferred Doppler parameters are considerably less than the widths derived from Lyα profile fitting, b/bwidth = 0.52. The typical increase in column density over that derived from profile fitting is Δ log N = 0.3, but ranges up to 1.0 dex. Our data suggest that the low-z Lyα absorbers contain sizable nonthermal motions or velocity components in the line profile, perhaps arising from cosmological expansion and infall.

We report on observations of the dM1e flare star AU Microscopii obtained with the Space Telescope Imaging Spectrograph (STIS) on 1998 September 6. A total of 10,105 s of observations were obtained with the medium-resolution E140M grating. We report here on the 9200 s of "quiescent" data when the star did not obviously flare. In this data set, we identify 142 emission lines from 28 species, including low-temperature chromospheric lines (e.g., C I, O I), transition-region lines (e.g., C II-IV, N IV, O III-V, Si II-IV), and the coronal line Fe XXI 1354 A. There are a number of intersystem lines that are useful for measuring electron densities. We discuss line redshifts and the broad wings of transition-region lines that provide evidence of microflare heating. We derive the emission-measure distribution and compare it with the solar one. We also discuss the shape and formation mechanisms of the He II 1640 A lines. The analysis of the flare data and of the interstellar absorption features seen in the H I, D I, C II, and O I resonance lines will be published elsewhere.

We present the first broadband, coronagraphic Hubble Space Telescope images of the bright, optically visible, isolated Herbig Ae star AB Aurigae. The Space Telescope Imaging Spectrograph (STIS) images reveal extended circumstellar nebulosity (r ≈ 1300 AU) covering the region of the millimeter continuum and CO disk. The structure is observed in the disk on spatial scales down to 01 (14 AU) and exhibits a north-south asymmetry. A comparison of the STIS data with scattering models for flared disks or disks + envelopes suggests that the disk inclination is i ≤ 45° from the plane of the sky.

We present a spectrophotometric imaging study of the emission bubble N70 (DEM 301) in the Large Magellanic Cloud. N70 is approximately 100 pc in size with a nearly circular shell-like morphology. The nebular emission is powered by an uncertain combination of EUV photons, intense winds, and supernova shock waves from the central population of high-mass stars (the OB association LH 114). We have obtained narrowband images (FWHM ~ 6 A) of N70 in the light of Hα λ6563, [N ii] λ6584, [S ii] λλ6717, 6731, and [O iii] λ5007, along with the corresponding red and green continua. The resulting line fluxes and flux ratios are used to derive ionization rates, nebular densities, volume filling fractions, and excitation indices. The photoionizing luminosity inferred from the embedded stellar population is more than adequate to account for the observed hydrogen ionization rate.We compare the emission-line photometry with that derived from similar imaging of the Orion Nebula and with data collected from the literature on other emission-line regions in the LMC. Compared with the Orion Nebula, N70 shows much higher [S ii]/Hα intensity ratios that increase smoothly with radius—from less than 0.3 near the center to greater than 1.0 toward the outer filamentary shell. The measured intensity ratios in N70 more closely match the range of excitation spanned by giant and supergiant H ii shells and by some of the supernova remnants observed in the LMC. The contending ionization and excitation processes in the interior and outer shell of N70 are evaluated in terms of the available data. EUV photons probably contribute most of the inner nebula's ionization, whereas a combination of photoionization plus collisional ionization and excitation of sulfur atoms by low-velocity shocks seems to best fit the emission-line luminosities and intensity ratios observed in the outer shell. Considerations of the radiative and mechanical energetics that are involved may indicate the need for one or two supernova explosions having occurred during the last ~Myr.

We present theoretical calculations of temporal variations in the nonthermal redshifted Lyα emission due to time-invariant proton beams injected into a stellar atmosphere during the impulsive phase of a flare. The computations are performed for a power-law spectrum of nonthermal proton energies injected into a model stellar atmosphere consisting of pure hydrogen in local thermodynamic equilibrium; beam-induced variations in temperature and particle densities at all depths and for all times are calculated with the Saha equation. We characterized the injected model proton beams with the total energy flux and the power-law index δ and computed time-dependent nonthermal redshifted Lyα emission profiles for five different values of and three different values of δ. Based upon trends evident in the resulting emission, proton beam properties can be deduced from sufficiently high-quality observations of the nonthermal redshifted Lyα profile. The beam penetration depth initially decreases with time, but in most cases it increases again after reaching some minimum value. This behavior is due to changes in the ionization and temperature of the atmosphere. The Lyα intensity also initially decreases with time, but in most cases it reaches a relative minimum, increases again to a secondary relative maximum, and then slowly but steadily decreases thereafter. Observable properties of this time-dependent emission, such as the ratio of the profile's peak spectral intensity at relative minimum to that at beam onset (Irelmin/I0), the difference between the profile's width at beam onset and that at the secondary relative maximum (FWHM0-FWHMrelmax), and the difference between the profile's centroid wavelength shift at beam onset and that at relative minimum (Δλ0-Δλrelmin) can be used to deduce δ. Once δ is known, can be deduced from other observable properties such as I0 and the times since beam onset at which the Lyα intensity reaches its relative minimum and secondary relative maximum values (trelmin and trelmax).

We present the spectrum and the pulse profile of the Crab Pulsar in the near-ultraviolet (1600-3200 A) observed with the Space Telescope Imaging Spectrograph (STIS) during the Hubble Space Telescope (HST) second Servicing Mission Orbital Verification (SMOV) period. The two-dimensional near-ultraviolet Multianode Microchannel Array (NUV MAMA) was used in time-tag mode with a 2''×2'' aperture and the low-dispersion grating, G230L, to obtain a cube with axes of slit position, wavelength, and time. The observation-derived pulse period is consistent with radio measurements, and the pulse profile agrees well with previous NUV broadband measurements by the High Speed Photometer. The pulsar spectrum includes the 2200 A dust absorption feature, plus several interstellar absorption lines. Dereddening the spectrum using the Savage-Mathis model with E(B-V)=0.55±0.05 leads to a good fit to a power law with slope αν = -0.3±0.2. The spectra of the main pulse, the interpulse, and the individual rising and falling edges are similar to the total spectrum within the limits of photon statistics. The four pulse profiles produced by breaking the spectrum into 400 A bins show the pulse profile to be stable across the NUV spectral range. Histogram analysis reveals no evidence for the superpulses seen at radio wavelengths. The interstellar absorption-line equivalent widths of Mg I, Mg II, and Fe II are lower than expected based on the implied H I column density from E(B-V)=0.5. While several explanations are possible, additional studies will be necessary to narrow the options.

We report the firstHubble Space TelescopeSpace Telescope Imaging Spectrograph (STIS) CCD spectroscopy of the bona fide brown dwarf Gliese 229B. The optical spectrum shows absorptions of Csi at 8944 Aand water vapor bands at 9300-9600 A ˚. Strong CaH, FeH, TiO, and VO bands observed in late M dwarfs are absent from the spectrum of Gliese 229B. The formation of dust grains may explain the absence of strong atomic lines and molecular bands of these refractory elements. The broad spectral coverage obtained helps resolve current spec- ulations about the presence of dust clouds in the atmosphere of cool brown dwarfs. We find the slope of the STIS/CCD spectrum and the lack of flux detected shortward of 8000 Astrongly supports the presence of dust hazes suspended in the photosphere of Gl 229B rather than a complete settling of the grains to regions below the photosphere. Subject headings: binaries: general — stars: individual (Gl 229B) — stars: low-mass, brown dwarfs

The Space Telescope Imaging Spectrograph (STIS) was successfully installed into the Hubble Space Telescope (HST) in 1997 February, during the second HST servicing mission, STS-82. STIS is a versatile spectrograph, covering the 115-1000 nm wavelength range in a variety of spectroscopic and imaging modes that take advantage of the angular resolution, unobstructed wavelength coverage, and dark sky offered by the HST. In the months since launch, a number of performance tests and calibrations have been carried out and are continuing. These tests demonstrate that the instrument is performing very well. We present here a synopsis of the results to date.

The cluster RX J1347.5-1145, the most luminous cluster in the X-ray wavelengths, was imaged with the newly installed Space Telescope Imaging Spectrograph (STIS) on-board HST. Its relatively high redshift (0.451) and luminosity indicate that this is one of the most massive of all known clusters. The STIS images unambiguously show several arcs in the cluster. The largest two arcs (> 5 arcsec in length) are symmetrically situated on opposite sides of the cluster, at a distance of ~ 35 arcsec from the central galaxy. The STIS images also show approximately 100 faint galaxies within the radius of the arcs whose combined luminosity is ~ 4 x 10^11 Lsun. We also present ground-based spectroscopic observations of the northern arc which show one clear emission line at 6730 A, which is consistent with an identification as [OII] 3727 A, implying a redshift of 0.81 for this arc. The southern arc shows a faint continuum but no emission features. The surface mass within the radius of the arcs (240 kpc), as derived from the gravitational lensing, is 6.3 x 10^14 Msun. The resultant mass-to-light ratio of ~1200 is higher than what is seen in many clusters but smaller than the value recently derived for some `dark' X-ray clusters (Hattori et al. 1997). The total surface mass derived from the X-ray flux within the radius of the arcs is ~2.1 - 6.8 x 10^14 Msun, which implies that the ratio of the gravitational to the X-ray mass is ~1 to 3. The surface GAS mass within this radius is ~3.5 x 10^13 Msun, which implies that at least 6% of the total mass within this region is baryonic., 3 figures. Replaced with the final version as appears in the Astrophysical Journal Letters (Jan 10, 1998 issue). This incorporates some important revisions

We describe the rationale and requirements for an integral-field spectrograph aboard NASA’s Terrestrial Planet Finder Coronagraph.

Spatially resolved scattered-light images of circumstellar (CS) debris in exoplanetary systems constrain the physical properties and orbits of the dust particles in these systems. They also inform on co-orbiting (but unseen) planets, systemic architectures, and forces perturbing starlight-scattering CS material. Using HST/STIS optical coronagraphy, we have completed the observational phase of a program to study the spatial distribution of dust in ten CS debris systems, and one "mature" protoplanetrary disk all with HST pedigree, using PSF-subtracted multi-roll coronagraphy. These observations probe stellocentric distances > 5 AU for the nearest stars, and simultaneously resolve disk substructures well beyond, corresponding to the giant planet and Kuiper belt regions in our Solar System. They also disclose diffuse very low-surface brightness dust at larger stellocentric distances. We present new results inclusive of fainter disks such as HD92945 confirming, and better revealing, the existence of a narrow inner debris ring within a larger diffuse dust disk. Other disks with ring-like sub-structures, significant asymmetries and complex morphologies include: HD181327 with a posited spray of ejecta from a recent massive collision in an exo-Kuiper belt; HD61005 suggested interacting with the local ISM; HD15115 & HD32297, discussed also in the context of environmental interactions. These disks, and HD15745, suggest debris system evolution cannot be treated in isolation. For AU Mic's edge-on disk, out-of-plane surface brightness asymmetries at > 5 AU may implicate one or more planetary perturbers. Time resolved images of the MP Mus proto-planetary disk provide spatially resolved temporal variability in the disk illumination. These and other new images from our program enable direct inter-comparison of the architectures of these exoplanetary debris systems in the context of our own Solar System., 109 pages, 43 figures, accepted for publication in the Astronomical Journal

We have discovered two new high redshift (z=2.38) galaxies, near the previously known z=2.38 galaxy 2139-4434 B1 (Francis et al. 1996). All three galaxies are strong Ly-alpha emitters, and have much redder continuum colors (I-K about 5) than other optically-selected high redshift galaxies. We hypothesize that these three galaxies are QSO IIs; radio-quiet counterparts of high redshift radio galaxies, containing concealed QSO nuclei. The red colors are most easily modelled by an old (> 0.5 Gyr), massive (> 10E11 solar masses) stellar population. If true, this implies that at least one galaxy cluster of mass much greater than 3E11 solar masses had collapsed before redshift five.

We present a novel optical integral field spectrograph (IFS) called the Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES), which will be a facility class instrument within the NASA Exoplanet Exploration Program's High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Laboratory. Integral field spectroscopy is ideal for imaging faint exoplanets: it enables spectral characterization of exoplanet atmospheres and can improve contrast by providing chromatic measurements of the target star's point-spread function (PSF). PISCES at the HCIT will be the first IFS to demonstrate imaging spectroscopy in the 10-9 contrast regime required for characterizing exoplanets imaged in scattered light. It is directly relevant as a prototype for IFS science instruments that could fly with the AFTA Coronagraph, the Exoplanet Probe missions currently under study, and/or the ATLAST mission concept. We present the instrument requirements, a baseline design for PISCES, a simulation of its performance, a solution to mitigate spectral crosstalk, experimental verification of our simulator, and the final vacuum compatible opto-mechanical design. PISCES will be assembled and tested at the Goddard Space Flight Center (GSFC), and subsequently delivered and integrated into the HCIT facility. Testing at HCIT will verify the performance of PISCES and its ability to meet the requirements of a space mission, will enable investigations into broadband wavefront control using the IFS as an image plane sensor, and will allow tests of contrast enhancement via multiwavelength differential imaging post-processing. Together with wavefront control and starlight suppression, PISCES is thus a key element for maturing the overall integrated system for a future coronagraphic space mission. PISCES is scheduled to receive first light in the HCIT in 2015.

The Goddard Fabry-Perot Imager (GFPI) is an optical scanning interferometer and CCD imaging system developed at the Goddard Space Flight Center’s Laboratory for Astronomy and Solar Physics for use at various astronomical observatories. Besides being transportable, its most notable characteristic is the relatively low spectral resolution (3 – 30Å bandpass). The instrument may be used in scanning mode for objects with a large range of velocities but is most often employed to match the observed wavelength of a Doppler shifted emission feature for objects with any velocity.

We present integral field spectroscopy of a Lyman-alpha blob at redshift 2.38, with a spectral resolution three times better than previous published work. As with previous observations, the blob has a chaotic velocity structure, much of which breaks up into multiple components. Our spectroscopy shows, however, that some of these multiple components are extremely narrow: they have velocity widths of less than 100 km/s. Combining these new data with previous observations, we argue that this Lyman-alpha blob resides in a dark-matter halo of around 10^13 solar masses. At the centre of this halo are two compact red massive galaxies. They are surrounded by hot gas, probably a super-wind from merger-induced nuclear starbursts. This hot gas has shut down star formation in the non-nuclear region of these galaxies, leading to their red-and-dead colours. A filament or lump of infalling cold gas is colliding with the hot gas phase and being shocked to high temperatures, while still around 30kpc from the red galaxies. The shock region is self-absorbed in Lyman-alpha but produces C IV emission. Further out still, the cold gas in a number of sub-halos is being lit up, most likely by a combination of tidally triggered star formation, bow-shocks as they plough through the hot halo medium, resonant scattering of Lyman-alpha from the filament collision, and tidal stripping of gas which enhances the Lyman-alpha escape fraction. The observed Lyman-alpha emission from the Blob is dominated by the sum of the emission from these sub-halos. On statistical grounds, we argue that Lyman-alpha blobs are not greatly elongated in shape, and that most are not powered by ionisation or scattering from a central active galactic nucleus or starburst., Accepted for publication in MNRAS