[en] We confirm the substellar nature of ULAS J141623.94+134836.3 (aka SDSS J1416+1348B), a common proper motion companion to the blue L dwarf SDSS J141624.08+134826.7 identified by Burningham et al. and Scholz. Low-resolution 0.8-2.4 μm spectroscopy obtained with the Infrared Telescope Facility/SpeX shows strong H₂O and CH₄ absorption bands, consistent with a T7.5 spectral type, and we see possible indications of NH₃ absorption in the 1.0-1.3 μm region. More importantly, the spectrum of SDSS J1416+1348B shows a broadened Y-band peak and highly suppressed K-band flux, both indicative of high surface gravity and/or subsolar metallicity. These traits are verified through spectral model fits, from which we derive atmospheric parameters T_eff = 650 ± 60 K, log g = 5.2 ± 0.4 cgs, [M/H] ≤ -0.3, and K_zz = 10⁴ cm² s^-1, the temperature being significantly warmer than that estimated by Burningham et al. These fits also indicate a model-dependent spectroscopic distance of 10.6^+3.0_-2.8 pc for SDSS J1416+1348B, formally consistent with the 7.9 ± 1.7 pc astrometric distance for SDSS J1416+1348A from Scholz. The common peculiarities of these two co-spatial, co-moving sources suggest that their unusual blue colors-and those of other blue L and T dwarfs in general-arise from age/gravity or metallicity effects, rather than cloud properties alone.

[en] Accidental release of light non aqueous phase liquids (LNAPLs, such as gasoline) into the subsurface can be a significant health and environmental concern. LNAPLs mostly reside in the zone of water table fluctuation and therefore, pose hazards in air (vapour) and water phases. The recovery and removal of LNAPLs through appropriate methods is a basic step in remediation of contaminated sites. Any technical approach such as pilot and field-scale trials to determine appropriate recovery methods for a particular site and condition may be expensive and time consuming. In addition, the long-term consequence and the endpoint of the recovery is not easily predictable. Simulation provide an avenue to assess this for a range of remediation options. Here we simulate field pilot trials to show how a multi-phase and multi-component framework can be used to determine the effective endpoint of LNAPL remedial options. (author)

[en] Near-infrared and 2.2-μm imaging polarimetry of the molecular cloud region OMC2, reveals a cluster of low- to intermediate-mass pre-main-sequence stars embedded in circumstellar discs. The 2.2-μm imaging polarimetry indicates that the compact near-IR sources OMC2 IRS1, IRS2, IRS3 and IRS4 N, are illumination centres for the surrounding extended emission. By application of Hubble's relation to the nebulae illuminated by IRS1, IRS2 and IRS4 N, we have been able to explain the illuminating geometry and estimate the intrinsic near-IR colours of these objects. IRS1 and IRS4 N each illuminate bipolar reflection nebulae, implying that the discs in which they are embedded are being viewed almost edge-on. Only one scattering lobe is seen near IRS2, suggesting that its disc is significantly more inclined to the line-of-sight. (author)

[en] Petroleum fuels are the most common and widespread contaminants requiring management in urban and industrial environments. These contaminants are commonly referred to as light non-aqueous phase liquids (LNAPLs)(Johnston 2010). LNAPLs are hydrophobic liquid organic chemicals with lower density than water and immiscible with water. They include a wide range of substances, but the most common types are oils and fuels, such as diesel, jet fuel and petrol (gasoline) (Kirkman, Adamski & Hawthorne 2013). In the present study the recovery of LNAPLs from a gasoline fine grained contaminated site in Western Australia is measured. The aim of this work is to evaluate the LNAPL recovery of the site via short term baildown tests versus recovery trials. Baildown tests have been proposed as a metric for the estimation of NAPL recovery but the majority have been conducted in homogeneous settings with little existed data from more complex subsurfaces. The calculation of the LNAPL transmissivity values was the outcome of the recovery tests. Wells with similar transmissivity values can be used and compared easier later during the remediation processes. (author)

[en] We present a 0.8-5 μm spectral library of 210 cool stars observed at a resolving power of R ≡ λ/Δλ ∼ 2000 with the medium-resolution infrared spectrograph, SpeX, at the 3.0 m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. The stars have well-established MK spectral classifications and are mostly restricted to near-solar metallicities. The sample not only contains the F, G, K, and M spectral types with luminosity classes between I and V, but also includes some AGB, carbon, and S stars. In contrast to some other spectral libraries, the continuum shape of the spectra is measured and preserved in the data reduction process. The spectra are absolutely flux calibrated using the Two Micron All Sky Survey photometry. Potential uses of the library include studying the physics of cool stars, classifying and studying embedded young clusters and optically obscured regions of the Galaxy, evolutionary population synthesis to study unresolved stellar populations in optically obscured regions of galaxies and synthetic photometry. The library is available in digital form from the IRTF Web site.

[en] We present a study of the stellar and circumstellar properties of Class I sources using low-resolution (R ∼ 1000) near-infrared (near-IR) K- and L-band spectroscopy. We measure prominent spectral lines and features in eight objects and use fits to standard star spectra to determine spectral types, visual extinctions, K-band excesses, and water ice optical depths. Four of the seven systems studied are close binary pairs; only one of these systems, Haro 6-10, was angularly resolvable. For certain stars, some properties found in our analysis differ substantially from published values; we analyze the origin of these differences. We determine extinction to each source using three different methods and compare and discuss the resulting values. One hypothesis that we were testing, that extinction dominates over the K-band excess in obscuration of the stellar photospheric absorption lines, appears not to be true. Accretion luminosities and mass accretion rates calculated for our targets are highly uncertain, in part the result of our inexact knowledge of extinction. For the six targets we were able to place on a Hertzsprung-Russell diagram, our age estimates, <2 Myr, are somewhat younger than those from comparable studies. Our results underscore the value of low-resolution spectroscopy in the study of protostars and their environments; however, the optimal approach to the study of Class I sources likely involves a combination of high- and low-resolution near-IR, mid-IR, and millimeter wavelength observations. Accurate and precise measurements of extinction in Class I protostars will be key to improving our understanding of these objects.

[en] We present a 0.7–2.5 μm spectral library of 284 stars observed with the medium-resolution infrared spectrograph, SpeX, at the 3.0 m NASA Infrared Telescope Facility (IRTF) on Maunakea, Hawaii. This library extends the metallicity range of the IRTF Cool Star library beyond solar metallicity to −1.7 < [Fe/H] < 0.6. All of the observed stars are also in the MILES optical stellar library, providing continuous spectral coverage for each star from 0.35 to 2.5 μm. The spectra are absolute flux calibrated using Two Micron All Sky Survey photometry, and the continuum shape of the spectra is preserved during the data reduction process. Synthesized JHK _S colors agree with observed colors at the 1%–2% level, on average. We also present a spectral interpolator that uses the library to create a data-driven model of spectra as a function of $T_{\mathrm{e}\mathrm{f}\mathrm{f}}$, $\mathrm{l}\mathrm{o}\mathrm{g}g$, and [Fe/H]. We use the library and interpolator to compare empirical trends with theoretical predictions of spectral feature behavior as a function of stellar parameters. These comparisons extend to the previously difficult to access low-metallicity and cool dwarf regimes, as well as the previously poorly sampled super-solar metallicity regime. The library and interpolator are publicly available.

[en] TWA 30 is a remarkable young (7 ± 3 Myr), low-mass (0.12 ± 0.04 M_sun), late-type star (M5 ± 1) residing 42 ± 2 pc away from the Sun in the TW Hydrae Association (TWA). It shows strong outflow spectral signatures such as [S II], [O I], [O II], [O III], and Mg I], while exhibiting weak Hα emission (-6.8 ± 1.2 A). Emission lines of [S II] and [O I] are common to T Tauri stars still residing in their natal molecular clouds, while [O III] and Mg I] emission lines are incredibly rare in this same population; in the case of TWA 30, these latter lines may arise from new outflow material colliding into older outflow fronts. The weak Hα emission and small radial velocity shifts of line emission relative to the stellar frame of rest (generally ∼<10 km s^-1) suggest that the disk is viewed close to edge-on and that the stellar axis may be inclined to the disk, similar to the AA Tau system, based on its temporal changes in emission/absorption line strengths/profiles and variable reddening (A_V = 1.5-9.0). The strong Li absorption (0.61 ± 0.13 A) and common kinematics with members of the TWA confirm its age and membership to the association. Given the properties of this system such as its proximity, low mass, remarkable outflow signatures, variability, and edge-on configuration, this system is a unique case study at a critical time in disk evolution and planet-building processes.

[en] During a synoptic survey of the North American Nebula region, the Palomar Transient Factory (PTF) detected an optical outburst (dubbed PTF10nvg) associated with the previously unstudied flat or rising spectrum infrared source IRAS 20496+4354. The PTF R-band light curve reveals that PTF10nvg brightened by more than 5 mag during the current outburst, rising to a peak magnitude of R_PTF ∼ 13.5 in 2010 September. Follow-up observations indicate that PTF10nvg has undergone a similar ∼5 mag brightening in the K band and possesses a rich emission-line spectrum, including numerous lines commonly assumed to trace mass accretion and outflows. Many of these lines are blueshifted by ∼175 km s^-1 from the North American Nebula's rest velocity, suggesting that PTF10nvg is driving an outflow. Optical spectra of PTF10nvg show several TiO/VO band heads fully in emission, indicating the presence of an unusual amount of dense (>10¹⁰ cm^-3), warm (1500-4000 K) circumstellar material. Near-infrared spectra of PTF10nvg appear quite similar to a spectrum of McNeil's Nebula/V1647 Ori, a young star which has undergone several brightenings in recent decades, and 06297+1021W, a Class I protostar with a similarly reached near-infrared emission line spectrum. While further monitoring is required to fully understand this event, we conclude that the brightening of PTF10nvg is indicative of enhanced accretion and outflow in this Class-I-type protostellar object, similar to the behavior of V1647 Ori in 2004-2005.

[en] We report here on a series of medium resolution spectro-photometric observations of the enigmatic long period eclipsing binary epsilon Aurigae, during its eclipse interval of 2009-2011, using near-infrared spectra obtained with SpeX on the Infrared Telescope Facility (IRTF), mid-infrared spectra obtained with BASS on AOES and IRTF, MIRSI on IRTF, and MIRAC4 on the MMT, along with mid-infrared photometry using MIRSI on IRTF and MIRAC4 on the MMT, plus 1995-2000 timeframe published photometry and data obtained with Denver's TNTCAM2 at WIRO. The goals of these observations included: (1) comparing eclipse depths with prior eclipse data, (2) confirming the re-appearance of CO absorption bands at and after mid-eclipse, associated with sublimation in the disk, (3) seeking evidence for any mid-infrared solid state spectral features from particles in the disk, and (4) providing evidence that the externally irradiated disk has azimuthal temperature differences. IR eclipse depths appear similar to those observed during the most recent (1983) eclipse, although evidence for post-mid-eclipse disk temperature increase is present, due to F star heated portions of the disk coming into view. Molecular CO absorption returned 57 days after nominal mid-eclipse, but was not detected at mid-eclipse plus 34 days, narrowing the association with differentially heated sub-regions in the disk. Transient He I 10830A absorption was detected at mid-eclipse, persisting for at least 90 days thereafter, providing a diagnostic for the hot central region. The lack of solid-state features in Spitzer Infrared Spectrograph, BASS, and MIRAC spectra to date suggests the dominance of large particles (micron-sized) in the disk. Based on these observations, mid-infrared studies out of eclipse can directly monitor and map the disk thermal changes, and better constrain disk opacity and thermal conductivity.