A Candidate Substellar Companion to HR 7329

We present the discovery of a candidate substellar companion from a survey of nearby, young stars with the NICMOS coronagraph on the Hubble Space Telescope. The H ~ 12 mag object was discovered approximately 4" from the young A0V star HR 7329. Using follow-up spectroscopy from STIS, we derive a spectral type between M7V and M8V with an effective temperature of ~ 2600 K. We estimate that the probability of a chance alignment with a foreground dwarf star of this nature is ~ 10^(-8) and therefore suggest the object (HR 7329B) is physically associated with HR 7329 with a projected separation of 200 AU. Current brown dwarf cooling models indicate a mass of less than 50 Jupiter masses for HR 7329B based on age estimates of < 30 Myr for HR7329A.Comment: 8 pages LATEX, 5 ps figures, accepted for Ap

The Late-time Expansion of the Ejecta of SN 1987A

The evolution of the shape and size of the ejecta of SN 1987A is analyzed over a period of ~ 8 years based on HST images and spectra taken between 1278 and 4336 days after the supernova outburst. We combine both proprietary and archival HST data obtained with the FOC, WFPC2 and STIS. The low resolution near-UV prism FOC spectrum obtained at day 3043 has not been described previously. Although the FWHM of the ejecta grew linearly over the time span studied, the appearance of the SN envelope also changed markedly with wavelength. At visible wavelengths (lambda ~ 5000 Angstrom) the ejecta became progressively more elongated, reaching an ellipticity epsilon ~ 0.25 by day 4000. In the near-UV (lambda ~ 2500 AA), the ejecta remained closely circular (epsilon <= 0.1) and ~ 50% larger in angular extent than in the visible. The FOC prism observations show that the large extent of the SN envelope is confined to a grouping of resonance lines spanning Mg I 2852, Mg II 2795,2802 and several Fe II multiplets -- thereby confirming that the larger size of the debris in the near-UV is due to scattering in these optically thick transitions compared to the optically thin forbidden and semi-forbidden transitions that dominate the visible spectrum. The available data are not of sufficient quality to detect the slight deviation from linear expansion expected for the outermost regions of the near-UV images as predicted by Chugai et al. (1997).Comment: Accepted for publication in A&A. 8 pages with 5 figures. Latex using Springer's A&A macros v4.0

Imaging and spectroscopy of arcs around the most luminous X-ray cluster RX J1347.5-1145

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.Comment: 3 figures. Replaced with the final version as appears in the Astrophysical Journal Letters (Jan 10, 1998 issue). This incorporates some important revision

An Infrared Coronagraphic Survey for Substellar Companions

We have used the F160W filter (1.4-1.8 um) and the coronagraph on the Near-InfraRed Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope (HST) to survey 45 single stars with a median age of 0.15 Gyr, an average distance of 30 pc, and an average H-magnitude of 7 mag. For the median age we were capable of detecting a 30 M_Jup companion at separations between 15 and 200 AU. A 5 M_Jup object could have been detected at 30 AU around 36% of our primaries. For several of our targets that were less than 30 Myr old, the lower mass limit was as low as a Jupiter mass, well into the high mass planet region. Results of the entire survey include the proper motion verification of five low-mass stellar companions, two brown dwarfs (HR7329B and TWA5B) and one possible brown dwarf binary (Gl 577B/C).Comment: 11 figures, accepted by A

Spatially Resolved STIS Spectroscopy of SN 1987A: Evidence for Shock Interaction with Circumstellar Gas

Visual and ultraviolet spatially resolved (~ 0."1) spectra of SN 1987A obtained on days 3715 and 3743 with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope show that the high-velocity SN debris is colliding with circumstellar gas. Very broad Ly-alpha emission with velocities extending to ~ +/- 20,000 km/s originates inside the inner circumstellar ring and appears to fill most of the surface area within 0."67 +/- 0."03 (0.14 pc at a distance of 50 kpc) of the ring's center. The observed Ly-alpha flux from the shocked ejecta is (1.85 +/- 0.53) 10^{-13} erg/cm2/s and (1.25 +/- 0.51) 10^{-12} erg/cm2/s after correcting for extinction. A spatially unresolved blue-shifted emission feature was discovered in H-alpha (and other lines) on the inner ring at p.a. 31 +/- 8 degree. The H-alpha emission extends to -250 km/s with no corresponding red-shifted emission. This highly localized interaction appears to be the initial contact of the supernova blast wave with an inward protrusion of the inner ring. The broad Ly-alpha emission and the `hot spot' are separate interaction phemonena associated with the reverse and forward shocks, respectively. We also find that the size of the inner ring in forbidden lines of oxygen has a dependence on ionization potential, in agreement with photoionization models of the ring.Comment: 11 pages (LaTeX, aaspp4.sty), 8 figures, accepted for publication in the Astrophysical Journal Letters HST Second Servicing Mission special issu

The Distances of the Magellanic Clouds

The present status of our knowledge of the distances to the Magellanic Clouds is evaluated from a post-Hipparcos perspective. After a brief summary of the effects of structure, reddening, age and metallicity, the primary distance indicators for the Large Magellanic Cloud are reviewed: The SN 1987A ring, Cepheids, RR Lyraes, Mira variables, and Eclipsing Binaries. Distances derived via these methods are weighted and combined to produce final "best" estimates for the Magellanic Clouds distance moduli.Comment: Invited review article to appear in ``Post Hipparcos Cosmic Candles'', F. Caputo & A. Heck (Eds.), Kluwer Academic Publ., Dordrecht, in pres

Spatially resolved spectroscopy of planetary nebulae and their halos I. Five galactic disk objects

Strong mass loss off stars at the tip of the asymptotic giant branch (AGB) profoundly affects properties of these stars and their surroundings, including the subsequent planetary nebula (PN) stage. With this study we wanted to determine physical properties of mass loss by studying weakly emitting halos, focusing on objects in the galactic disk. Halos surround the, up to several thousand times, brighter central regions of PNe. Young halos, specifically, still contain information of the preceeding final mass loss stage on the AGB. In the observations we used the method of integral field spectroscopy with the PMAS instrument. This is the first committed study of halos of PNe that uses this technique. We improved our data analysis by a number of steps. In a study of the influence of scattered light we found that a moderate fraction of intensities in the inner halo originate in adjacent regions. As we combine line intensities of distant wavelengths, and because radial intensity gradients are steep, we corrected for effects of differential atmospheric refraction. In order to increase the signal-to-noise of weak emission lines we introduced a dedicated method to bin spectra of individual spatial elements. We also developed a general technique to subtract telluric lines - without using separate sky exposures. By these steps we avoided introducing errors of several thousand Kelvin to our temperature measurements in the halo. For IC3568 we detected a halo. For M2-2 we found a halo radius that is 2.5 times larger... (abridged)Comment: 27 pages, 29 figures, A&A (in press), Abridged abstract, Corrected and clarified various minor issues; the section on scattered light is significantly clarifie

Spectroscopy of SN 1987A at 0.9-2.4 microns: Days 1348-3158

We present near-infrared spectroscopic observations of SN 1987A covering the period 1358 to 3158 days post-explosion. This is the first time that IR spectra of a supernova have been obtained to such late epochs. The spectra comprise emission from both the ejecta and the bright, ring-shaped circumstellar medium (CSM). The most prominent CSM emission lines are recombination lines of H I and He I, and forbidden lines of [S III] and [Fe II]. The ejecta spectra include allowed lines of H I, He I and Na I and forbidden lines of [Si I], [Fe I], [Fe II], and possibly [S I]. The intensity ratios and widths of the H I ejecta lines are consistent with a low-temperature Case B recombination spectrum arising from non-thermal ionisation/excitation in an extended, adiabatically cooled H-envelope, as predicted by several authors. The slow decline of the ejecta forbidden lines, especially those of [Si I], indicates that pure non-thermal excitation was taking place, driven increasingly by the decay of 44Ti. The ejecta iron exhibits particularly high velocities (4000-4500 km/s), supporting scenarios where fast radioactive nickel is created and ejected just after the core-bounce. In addition, the ejecta lines continue to exhibit blueshifts with values about -200 km/s to -800 km/s to at least day 2000. These blueshifts, which first appeared around day 600, probably indicate that very dense concentrations of dust persist in the ejecta, although an alternative explanation of asymmetry in the excitation conditions is not ruled out.Comment: 18 pages, 8 figures, uses mn.sty, MNRAS, in pres

Clarifying anti-reflexivity: Conservative opposition to impact science and scientific evidence

The recent study reported by McCright et al (2013 Environ. Res. Lett. 8 044029) extends current research on conservatives' distrust of science by distinguishing between public trust in production versus impact scientists (i.e. those whose work yields new technologies and marketable products versus those assessing the health and environmental impacts of such technologies and products). As expected, they find that conservatives are significantly less trustful of impact scientists but somewhat more trustful of production scientists. In the process they provide support for the Anti-Reflexivity Thesis, a perspective that attributes conservatives' (and Republicans') denial of anthropogenic climate change (ACC) and other environmental problems and attacks on climate/environmental science to their staunch commitment to protecting the current system of economic production. McCright et al's innovative study deserves replication, and their approach should prove useful in accounting for divergent views of ACC. It is also important to keep in mind that anti-reflexivity is an institutional and structural issue, becoming more consequential when it is employed by political elites such as the George W Bush Administration in the US. Institutional anti-reflexivity is further illustrated by the widespread denial of ACC and a range of other problems among current Republican members of the US Congress.Peer reviewedSociolog

The Nuclear Dynamics of M32. I. Data and Stellar Kinematics

We have obtained optical long-slit spectroscopy of the nucleus of M32 using the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. The stellar rotation velocity and velocity dispersion, as well as the full line-of-sight velocity distribution (LOSVD), were determined as a function of position along the slit using two independent spectral deconvolution algorithms. We see three clear kinematical signatures of the nuclear black hole: a sudden upturn, at ~0.3 arc seconds from the center, in the stellar velocity dispersions; a flat or rising rotation curve into the center; and strong, non-Gaussian wings on the central LOSVD. The central velocity dispersion is ~130 km/s (Gaussian fit) or ~175 km/s (corrected for the wings). Both the velocity dispersion spike and the shape of the central LOSVD are consistent with the presence of a supermassive compact object in M32 with a mass in the range 2-5 x 10^6 solar masses. These data are a significant improvement on previous stellar kinematical data, making M32 the first galaxy for which the imprint of the black hole's gravitation on the stellar velocities has been observed with a resolution comparable to that of gas-dynamical studies.Comment: 55 pages, 17 figures. Submitted to The Astrophysical Journa