The 1990 MB: The first Mars Trojan

Asteroid 1990 MB was discovered by D. H. Levy and H. E. Holt during the course of the Mars and Earth Crossing Asteroid and Comet Survey. An orbit based on a 9 day arc and the asteroid's location near Mars' L5 (trailing Lagrangean) longitude led E. Boswell to speculate that it might be in 1:1 resonance with Mars, analogous to the Trojan asteroids of Jupiter. Subsequent observations strengthened the possibility, and later calculations confirmed it. Thus 1990 MB is the first known asteroid in 1:1 resonance with a planet other than Jupiter. The existence of 1990 MB (a small body most likely between 2 and 4 km in diameter) provides remarkable confirmation of computer simulations. These self consistent n-body simulations demonstrated this sort of stability for Trojans of all the terrestrial planets over at least a 2 million year time base. The discovery of 1990 MB suggests that others of similar or smaller diameter may be found. Using hypothetical populations of Mars Trojans, their possible sky plane distributions were modeled as a first step in undertaking a systematic observational search of Mars' L4 and L5 libration regions

Dynamic equilibrium correction modelling of yen Eurobond credit spreads

Understanding the long term relationship between the yields of risky and riskless bonds is a critical task for portfolio managers and policy makers. This study specifies an equilibrium correction model of the credit spreads between Japanese Government bonds (JGBs) and Japanese yen Eurobonds with high quality credit ratings. The empirical results indicate that the corporate bond yields are cointegrated with the otherwise equivalent JGB yields, with the spread defining the cointegration relation. In addition the results indicate that the equilibrium correction term is highly statistically significant in modelling credit spread changes. Another important factor is the risk-free interest rate with the negative sign, while there is little evidence of the contribution of the asset return to the behaviour of spreads.

Early-time Spitzer observations of the type II-Plateau supernova, 2004dj

We present mid-infrared observations with the Spitzer Space Telescope of the nearby type II-P supernova, SN 2004dj, at epochs of 89 to 129 days. We have obtained the first mid-IR spectra of any supernova apart from SN 1987A. A prominent [NiII] 6.64 micron line is observed, from which we deduce that the mass of stable nickel must be at least 2.2e10(-4) Msun. We also observe the red wing of the CO-fundamental band. We relate our findings to possible progenitors and favour an evolved star, most likely a red supergiant, with a probable initial mass between ~10 and 15 Msun.Comment: ApJ Letters (accepted

Gaia transient detection efficiency: hunting for nuclear transients

We present a study of the detectability of transient events associated with galaxies for the Gaia European Space Agency astrometric mission. We simulated the on-board detections, and on-ground processing for a mock galaxy catalogue to establish the properties required for the discovery of transient events by Gaia, specifically tidal disruption events (TDEs) and supernovae (SNe). Transients may either be discovered by the on-board detection of a new source or by the brightening of a previously known source. We show that Gaia transients can be identified as new detections on-board for offsets from the host galaxy nucleus of 0.1--0.5,arcsec, depending on magnitude and scanning angle. The Gaia detection system shows no significant loss of SNe at close radial distances to the nucleus. We used the detection efficiencies to predict the number of transients events discovered by Gaia. For a limiting magnitude of 19, we expect around 1300 SNe per year: 65% SN Ia, 28% SN II and 7% SN Ibc, and ~20 TDEs per year.Comment: 17 pages, 10 figures, accepted by MNRA

Ion-Exchanged Waveguides in Glass Doped with PbS Quantum Dots

The lowest-loss (≤1 dB/cm) ion-exchanged waveguides in glass doped with PbS quantum dots are presented. Near-field mode profile and refractive index profile using the refracted near-field technique were measured for these waveguides. We demonstrate that the optical properties of this glass unchanged during the ion-exchange process

Proposal review rankings: the influence of reviewer discussions on proposal selection

The telescope time allocation process for NASA's Great Observatories involves a substantial commitment of time and expertise by the astronomical community. The annual review meetings typically have 100 external participants. Each reviewer spends 3-6 days at the meeting in addition to one-two weeks of preparation time, reading and grading proposals. The reviewers grade the proposals based on their individual reading prior to the meeting and grade them again after discussion within the broad, subject-based review panels. We summarize here how the outcome of the review process for three Spitzer observing cycles would have changed if the selection had been done strictly based on the preliminary grades without having the panels meet and discuss the proposals. The changes in grading during the review meeting have a substantial impact on the final list of selected proposals. Approximately 30% of the selected proposals would not have been included if just the preliminary rankings had been used to make the selection

Spitzer measurements of atomic and molecular abundances in the Type IIP SN 2005af

We present results based on Spitzer Space Telescope mid-infrared (3.6-30 micron) observations of the nearby IIP supernova 2005af. We report the first ever detection of the SiO molecule in a Type IIP supernova. Together with the detection of the CO fundamental, this is an exciting finding as it may signal the onset of dust condensation in the ejecta. From a wealth of fine-structure lines we provide abundance estimates for stable Ni, Ar, and Ne which, via spectral synthesis, may be used to constrain nucleosynthesis models.Comment: ApJ Letters (accepted

High Density Circumstellar Interaction in the Luminous Type IIn SN 2010jl: The first 1100 days

HST and ground based observations of the Type IIn SN 2010jl are analyzed, including photometry, spectroscopy in the ultraviolet, optical and NIR bands, 26-1128 days after first detection. At maximum the bolometric luminosity was $\sim 3\times10^{43}$ erg/s and even at 850 days exceeds $10^{42}$ erg/s. A NIR excess, dominating after 400 days, probably originates in dust in the circumstellar medium (CSM). The total radiated energy is $> 6.5\times10^{50}$ ergs, excluding the dust component. The spectral lines can be separated into one broad component due to electron scattering, and one narrow with expansion velocity $\sim 100$ km/s from the CSM. The broad component is initially symmetric around zero velocity but becomes blueshifted after $\sim 50$ days, while remaining symmetric about a shifted centroid velocity. Dust absorption in the ejecta is unlikely to explain the line shifts, and we attribute the shift instead to acceleration by the SN radiation. From the optical lines and the X-ray and dust properties, there is strong evidence for large scale asymmetries in the CSM. The ultraviolet lines indicate CNO processing in the progenitor, while the optical shows a number of narrow coronal lines excited by the X-rays. The bolometric light curve is consistent with a radiative shock in an $r^{-2}$ CSM with a mass loss rate of $\sim 0.1$ M_sun/yr. The total mass lost is $> 3$ M_sun. These properties are consistent with the SN expanding into a CSM characteristic of an LBV progenitor with a bipolar geometry. The apparent absence of nuclear processing is attributed to a CSM still opaque to electron scattering.Comment: ApJ in press. Updated and changed after referees comment

Warm Molecular Hydrogen Emission in Normal Edge-On Galaxies NGC 4565 and NGC 5907

We have observed warm molecular hydrogen in two nearby edge-on disk galaxies, NGC 4565 and NGC 5907, using the Spitzer high-resolution infrared spectrograph. The 0-0 S(0) 28.2 micron and 0-0 S(1) 17.0 micron pure rotational lines were detected out to 10 kpc from the center of each galaxy on both sides of the major axis, and in NGC 4565 the S(0) line was detected at r = 15 kpc on one side. This location lies beyond a steep drop in the radio continuum emission from cosmic rays in the disk. Despite indications that star formation activity decreases with radius, the H2 excitation temperature and the ratio of the H2 line and the far-IR luminosity surface densities, Sigma_L(H2}/Sigma_L(TIR}, change very little as a function of radius, even into the diffuse outer region of the disk of NGC 4565. This suggests that the source of excitation of the H2 operates over a large range of radii, and is broadly independent of the strength and relative location of UV emission from young stars. Although excitation in photodissociation regions is the most common explanation for the widespread H2 emission, cosmic ray heating or shocks cannot be ruled out. The inferred mass surface densities of warm molecular hydrogen in both edge-on galaxies differ substantially, being 4(-60) M_solar/pc^2 and 3(-50) M_solar/pc^2 at r = 10 kpc for NGC 4565 and NGC 5907, respectively. The higher values represent very unlikely point-source upper limits. The point source case is not supported by the observed emission distribution in the spectral slits. These mass surface densities cannot support the observed rotation velocities in excess of 200 km/s. Therefore, warm molecular hydrogen cannot account for dark matter in these disk galaxies, contrary to what was implied by a previous ISO study of the nearby edge-on galaxy NGC 891.Comment: Accepted for publication in the Astronomical Journal (20 pages, 17 figures, 7 tables