Spitzer IRS Pipelines for General Users

An effort is underway to make the Spitzer InfraRed Spectrograph (IRS) data-processing pipelines available for use by astronomers worldwide. This will allow users to reprocess raw data downloaded from the Spitzer archive with customized calibration files, updated operational parameters, and/or a modified list of processing steps. The pipelines will create all standard BCD (basic calibrated data) and post-BCD products, plus additional intermediate products. The pipelines will be made up of newly developed Perl and C-shell ``executive'' scripts, plus the binary-executable modules currently used in operations (the modules' source code will not be distributed, however). The scripts are being designed for ease of use and will facilitate user-customization. The operating systems targeted for support are Mac OS X, Linux, Solaris, and possibly Windows

Wide-Field Infrared Survey Explorer Observations of Young Stellar Objects in the Lynds 1509 Dark Cloud in Auriga

The Wide-Field Infrared Survey Explorer (WISE) has uncovered a striking cluster of young stellar object (YSO) candidates associated with the L1509 dark cloud in Auriga. The WISE observations, at 3.4 μm, 4.6 μm, 12 μm, and 22 μm, show a number of objects with colors consistent with YSOs, and their spectral energy distributions suggest the presence of circumstellar dust emission, including numerous Class I, flat spectrum, and Class II objects. In general, the YSOs in L1509 are much more tightly clustered than YSOs in other dark clouds in the Taurus-Auriga star forming region, with Class I and flat spectrum objects confined to the densest aggregates, and Class II objects more sparsely distributed. We estimate a most probable distance of 485-700 pc, and possibly as far as the previously estimated distance of 2 kpc

Visual Orbits & Alignments of Planet Hosting Binary Systems

Roughly half of Solar-type planet hosts have stellar companions, so understanding how these binary companions affect the formation and evolution of planets is an important component to understanding planetary systems overall. Measuring the dynamical properties of planet host binaries enables a valuable test of planet formation in multi-star systems and requires knowledge of the binary orbital parameters. Using high resolution imaging, we have measured the relative astrometry and visual orbits of 13 binary systems where one of the stars is known to host a transiting exoplanet. Our results indicate that the mutual inclination between the orbits of the binary hosts and the transiting planets are well aligned. Our results for close binary systems (a<100 AU) complement past work for wide planet host binaries from Gaia.Comment: Accepted for publication in A

Radii of 88 M subdwarfs and updated radius relations for low-metallicity M-dwarf stars

M subdwarfs are low-metallicity M dwarfs that typically inhabit the halo population of the Galaxy. Metallicity controls the opacity of stellar atmospheres; in metal-poor stars, hydrostatic equilibrium is reached at a smaller radius, leading to smaller radii for a given effective temperature. We compile a sample of 88 stars that span spectral classes K7 to M6 and include stars with metallicity classes from solar-metallicity dwarf stars to the lowest metallicity ultra subdwarfs to test how metallicity changes the stellar radius. We fit models to Palomar Double Spectrograph (DBSP) optical spectra to derive effective temperatures (T_ eff) and we measure bolometric luminosities (L_ bol) by combining broad wavelength-coverage photometry with Gaia parallaxes. Radii are then computed by combining the T_ eff and L_ bol using the Stefan–Boltzman law. We find that for a given temperature, ultra subdwarfs can be as much as five times smaller than their solar-metallicity counterparts. We present color-radius and color-surface brightness relations that extend down to [Fe/H] of −2.0 dex, in order to aid the radius determination of M subdwarfs, which will be especially important for the WFIRST exoplanetary microlensing survey.Published versio

NEOWISE-R Observation of the Coolest Known Brown Dwarf

The Wide-field Infrared Survey Explorer (WISE) spacecraft has been reactivated as NEOWISE-R to characterize and search for Near Earth Objects. The brown dwarf WISE J085510.83-071442.5 has now been reobserved by NEOWISE-R, and we confirm the results of Luhman (2014b), who found a very low effective temperature ($\approx 250$ K), a very high proper motion (8.1 +/- 0.1 arcsec/yr) , and a large parallax (454 +/- 45 mas). The large proper motion has separated the brown dwarf from the background sources that influenced the 2010 WISE data, allowing a measurement of a very red WISE color of W1-W2 $> 3.9$ mag. A re-analysis of the 2010 WISE astrometry using only the W2 band, combined with the new NEOWISE-R 2014 position, gives an improved parallax of 448 +/- 33 mas and proper motion of 8.08 +/- 0.05\; arcsec/yr. These are all consistent with Luhman (2014b).Comment: 6 pages, AJ accepte

Discovery of the Young L Dwarf WISE J174102.78–464225.5

We report the discovery of the L dwarf WISE J174102.78–464225.5, which was discovered as part of a search for nearby L dwarfs using the Wide-field Infrared Survey Explorer (WISE). The distinct triangular peak of the H-band portion of its near-infrared spectrum and its red near-infrared colors (J – K_S = 2.35 ± 0.08 mag) are indicative of a young age. Via comparison to spectral standards and other red L dwarfs, we estimate a near-infrared spectral type of L7 ± 2 (pec). From a comparison to spectral and low-mass evolutionary models, we determine self-consistent effective temperature, log g, age, and mass values of 1450 ± 100 K, 4.0 ± 0.25 (cm s^(–2)), 10-100 Myr, and 4-21 M_(Jup), respectively. With an estimated distance of 10-30 pc, we explore the possibility that WISE J174102.78–464225.5 belongs to one of the young nearby moving groups via a kinematic analysis and we find potential membership in the β Pictoris or AB Doradus associations. A trigonometric parallax measurement and a precise radial velocity can help to secure its membership in either of these groups

Discovery of a Possible Cool White Dwarf Companion from the AllWISE Motion Survey

We present optical and near-infrared spectroscopy of WISEA J061543.91−124726.8, which we rediscovered as a high motion object in the AllWISE survey. The spectra of this object are unusual; while the red optical (λ > 7000 Å) and near-infrared spectra exhibit characteristic TiO, VO, and H_2O bands of a late-M dwarf, the blue portion of its optical spectrum shows a significant excess of emission relative to late-M-type templates. The excess emission is relatively featureless, with the exception of a prominent and very broad Na I D doublet. We find that no single, ordinary star can reproduce these spectral characteristics. The most likely explanation is an unresolved binary system of an M7 dwarf and a cool white dwarf. The flux of a cool white dwarf drops in the optical red and near-infrared, due to collision-induced absorption, thus allowing the flux of a late-M dwarf to show through. This scenario, however, does not explain the Na D feature, which is unlike that of any known white dwarf, but which could perhaps be explained via unusual abundance or pressure conditions

Joint Survey Processing I: Compact oddballs in the COSMOS field -- low-luminosity Quasars at z > 6?

The faint-end slope of the quasar luminosity function at z~6 and its implication on the role of quasars in reionizing the intergalactic medium at early times has been an outstanding problem for some time. The identification of faint high-redshift quasars with luminosities of 25mag, with ~30% of sources having their flux contaminated by foreground objects when the seeing resolution is ~0.7". We mitigate these issues by performing a pixel-level joint processing of ground and space-based data from Subaru/HSC and HST/ACS. We create a deconfused catalog over the 1.64 deg² of the COSMOS field, after accounting for spatial varying PSFs and astrometric differences between the two datasets. We identify twelve low-luminosity (M_(UV) ~ -21 mag) z>6 quasar candidates through (i) their red color measured between ACS/F814W and HSC/i-band and (ii) their compactness in the space-based data. We estimate that late-type stars could contribute up to 50% to our sample. Our constraints on the faint end of the quasar luminosity function at z~6.4 suggests a negligibly small contribution to reionization compared to the star-forming galaxy population. The confirmation of our candidates and the evolution of number density with redshift could provide better insights into how supermassive galaxies grew in the first billion years of cosmic time

Revised Properties and Dynamical History for the HD 17156 System

From the thousands of known exoplanets, those that transit bright host stars provide the greatest accessibility toward detailed system characterization. The first known such planets were generally discovered using the radial velocity technique, then later found to transit. HD 17156b is particularly notable among these initial discoveries because it diverged from the typical hot Jupiter population, occupying a 21.2 day eccentric ($e = 0.68$) orbit, offering preliminary insights into the evolution of planets in extreme orbits. Here we present new data for this system, including ground and space-based photometry, radial velocities, and speckle imaging, that further constrain the system properties and stellar/planetary multiplicity. These data include photometry from the Transiting Exoplanet Survey Satellite (TESS) that cover five transits of the known planet. We show that the system does not harbor any additional giant planets interior to 10 AU. The lack of stellar companions and the age of the system indicate that the eccentricity of the known planet may have resulted from a previous planet-planet scattering event. We provide the results from dynamical simulations that suggest possible properties of an additional planet that culminated in ejection from the system, leaving a legacy of the observed high eccentricity for HD 17156b.Comment: 15 pages, 7 figures, accepted for publication in the Astronomical Journa