Trent J. Dupuy

NEAR-INFRARED SPECTROSCOPY OF THE EXTRASOLAR PLANET HR 8799 b*

We present 2.12-2.23 ?m high contrast integral field spectroscopy of the extrasolar planet HR?8799 b. Our observations were obtained with OSIRIS on the Keck II telescope and sample the 2.2 ?m CH4 feature, which is useful for spectral classification and as a temperature diagnostic for ultracool objects. The spectrum of HR?8799 b is relatively featureless, with little or no methane absorption, and does not exhibit the strong CH4 seen in T dwarfs of similar absolute magnitudes. The spectrum is consistent with field objects from early-L to T4 (3? confidence level), with a best-fitting type of T2. A similar analysis of the published 1-4 ?m photometry shows the infrared spectral energy distribution (SED) matches L5-L8 field dwarfs, especially the reddest known objects which are believed to be young and/or very dusty. Overall, we find that HR?8799 b has a spectral type consistent with L5-T2, although its SED is atypical compared to most field objects. We fit the 2.2 ?m spectrum and the infrared SED using the Hubeny & Burrows, Burrows et?al., and Ames-Dusty model atmosphere grids, which incorporate non-equilibrium chemistry, non-solar metallicities, and clear and cloudy variants. No models agree with all of the data, but those with intermediate clouds produce significantly better fits. The largest discrepancy occurs in the J band, which is highly suppressed in HR?8799 b. Models with high eddy diffusion coefficients and high metallicities are somewhat preferred over those with equilibrium chemistry and solar metallicity. The best-fitting effective temperatures range from 1300 to 1700?K with radii between ~0.3 and 0.5 R Jup. These values are inconsistent with evolutionary model-derived values of 800-900?K and 1.1-1.3 R Jup based on the luminosity of HR?8799 b and the age of HR?8799, a discrepancy that probably results from imperfect atmospheric models or the limited range of physical parameters covered by the models. The low temperature inferred from evolutionary models indicates that HR?8799 b is ~400?K cooler than field L/T transition objects, providing further evidence that the L/T transition is gravity-dependent. With an unusually dusty photosphere, an exceptionally low luminosity for its spectral type, and hints of extreme secondary physical parameters, HR?8799 b appears to be unlike any class of field brown dwarf currently known.

CLUSTER MASS FUNCTIONS IN THE LARGE AND SMALL MAGELLANIC CLOUDS: FADING AND SIZE-OF-SAMPLE EFFECTS

The properties of ~939 star clusters in the Large and Small Magellanic Clouds were determined from ground-based CCD images in UBVR passbands. The areal coverage was extensive, corresponding to 11.0 kpc2 in the LMC and 8.3 kpc2 in the SMC. After corrections for reddening, the colors and magnitudes of the clusters were converted to ages and masses, and the resulting mass distributions were searched for the effects of fading, evaporation, and size-of-sample bias. The data show a clear signature of cluster fading below the detection threshold. The initial cluster mass function (ICMF) was determined by fitting the mass and age distributions with cluster population models. These models suggest a new method to determine the ICMF that is nearly independent of fading or disruption and is based on the slope of a correlation between age and the maximum cluster mass in equally spaced intervals of log age. For a nearly uniform star formation rate, this correlation has a slope equal to 1/(α - 1) for an ICMF of dn(M)/dM ∝ M-α. We determine that α is between 2 and 2.4 for the LMC and SMC using this method plus another method in which models are fitted to the mass distribution integrated over age and to the age distribution integrated over mass. The maximum mass method also suggests that the cluster formation rate in the LMC age gap between 3 and 13 Gyr is about a factor of 10 below that in the period from 0.1 to 1 Gyr. The oldest clusters correspond in age and mass to halo globular clusters in the Milky Way. They do not fit the trends for lower mass clusters but appear to be a separate population that either had a very high star formation rate and became depleted by evaporation or formed with only high masses.

Subtle Signatures of Multiplicity in Late-type Dwarf Spectra: The Unresolved M8.5 + T5 Binary 2MASS J03202839-0446358

Evidence is presented that 2MASS J03202839� 0446358, a late-type dwarf with discrepant optical (M8:) and nearinfrared(L1)spectraltypes,isanas-yetunresolvedstellar/browndwarfbinarywithlate-typeMdwarfandTdwarfcomponents. This conclusion is based on low-resolution, near-infrared spectroscopy that reveals a subtle but distinctive absorption feature at 1.6 � m. The feature, which is also present in the combined light spectrum of the M8.5 + T6 binary SCR 1845� 6357, arises from the combination of FeH absorption from an M8.5 primary and pseudocontinuum flux from a T5 � 1 secondary, as ascertained from binary spectral templates constructed from empirical data. The binary templates provide a far superior match to the overall near-infrared spectral energy distribution of 2MASS J0320� 0446 than any single comparison spectra. Laser guide star adaptive optics (LGS AO) imaging observations, including the first application of LGS AO aperture mask interferometry, fail to resolve a faint companion, restricting the projected separation of the system to less than 8.3 AU at the time of observation. 2MASS J0320� 0446 is the second very low mass binary to be identified from unresolved, low-resolution, near-infrared spectroscopy, a technique that complements traditional high-resolution imaging and spectroscopic methods. Subject headingg binaries: general — stars: fundamental parameters — stars: individual — stars: low-mass, brown dwarfs

Dynamical Mass of the Substellar Benchmark Binary HD 130948BC

We present Keck adaptive optics imaging of the L4+L4 binary HD 130948BC along with archival Hubble Space Telescope and Gemini North observations, which together span ≈ 70% of the binary’s orbital period. From the relative orbit, we determine a total dynamical mass of 0.109 ± 0.003 M� (114 ± 3 MJup). The flux ratio of HD 130948BC is near unity, so both components are unambiguously substellar for any plausible mass ratio. An independent constraint on the age of the system is available from the primary HD 130948A (G2V, [M/H] = 0.0). The ensemble of available indicators suggests an age comparable to Hyades, with the most precise age being 0.79 +0.22 −0.15 Gyr based on gyrochronology. Therefore, HD 130948BC is now a unique benchmark among field L and T dwarfs, with a well-determined mass, luminosity, and age. We find that substellar theoretical models disagree with our observations. (1) Both components of HD 130948BC appear to be overluminous by a factor of ≈ 2–3 times compared to evolutionary models. The age of the system would have to be notably younger than the gyro age to ameliorate the luminosity disagreement. (2) Effective temperatures derived from evolutionary models for HD 130948B and C are inconsistent with temperatures determined from spectral synthesis for objects of similar spectral type. Overall, regardless of the adopted age, evolutionary and atmospheric models give inconsistent results, which indicate systematic errors in at least one class of models, possibly both. The masses of HD 130948BC happen to be very near the theoretical mass limit for lithium burning, and thus measuring the differential lithium depletion between B and C will provide a uniquely discriminating test of theoretical models. The potential underestimate of luminosities by evolutionary models would have wide-ranging implications; therefore, a more refined estimate age for HD 130948A is critically needed.

SEARCHING FOR YOUNG M DWARFS WITH GALEX

The census of young moving groups in the solar neighborhood is significantly incomplete in the low-mass regime. We have developed a new selection process to find these missing members based on the Galaxy Evolution Explorer (GALEX) All-Sky Imaging Survey (AIS). For stars with spectral types K5 (R – J 1.5) and younger than ≈300 Myr, we show that near-UV (NUV) and far-UV (FUV) emission is greatly enhanced above the quiescent photosphere, analogous to the enhanced X-ray emission of young low-mass stars seen by ROSAT but detectable to much larger distances with GALEX. By combining GALEX data with optical (HST Guide Star Catalog) and near-IR (2MASS) photometry, we identified an initial sample of 34 young M dwarf candidates in a 1000 deg2 region around the ≈10 Myr TW Hydra Association (TWA). Low-resolution spectroscopy of 30 of these found 16 which had Hα in emission, which were then followed up at high resolution to search for spectroscopic evidence of youth and to measure their radial velocities. Four objects have low surface gravities, photometric distances and space motions consistent with TWA, but the non-detection of Li indicates that they may be too old to belong to this moving group. One object (M3.5, 93 ± 19 pc) appears to be the first known accreting low-mass member of the ≈15 Myr Lower Centaurus Crux OB association. Two objects exhibit all the characteristics of the known TWA members, and thus we designate them as TWA 31 (M4.2, 110 ± 11 pc) and TWA 32 (M6.3, 53 ± 5 pc). TWA 31 shows extremely broad (447 km s–1) Hα emission, making it the sixth member of TWA found to have ongoing accretion. TWA 32 is resolved into a 06 binary in Keck laser guide star adaptive optics imaging. Our search should be sensitive down to spectral types of at least M4-M5 in TWA and thus the small numbers of new member is puzzling. This might indicate TWA has an atypical mass function or that the presence of lithium absorption may be too restrictive a criteria for selecting young low-mass stars.

The Gemini NICI Planet-Finding Campaign : Discovery of a Substellar L Dwarf Companion to the Nearby Young M Dwarf CD-35 2722

We present the discovery of a wide (67 AU) substellar companion to the nearby (21 pc) young solar-metallicity M1 dwarf CD-35 2722, a member of the ~100 Myr AB Doradus association. Two epochs of astrometry from the NICI Planet-Finding Campaign confirm that CD-35 2722 B is physically associated with the primary star. Near-IR spectra indicate a spectral type of L4\pm1 with a moderately low surface gravity, making it one of the coolest young companions found to date. The absorption lines and near-IR continuum shape of CD-35 2722 B agree especially well the dusty field L4.5 dwarf 2MASS J22244381-0158521, while the near-IR colors and absolute magnitudes match those of the 5 Myr old L4 planetary-mass companion, 1RXS J160929.1-210524 b. Overall, CD-35 2722 B appears to be an intermediate-age benchmark for L-dwarfs, with a less peaked H-band continuum than the youngest objects and near-IR absorption lines comparable to field objects. We fit Ames-Dusty model atmospheres to the near-IR spectra and find T=1700-1900 K and log(g) =4.5\pm0.5. The spectra also show that the radial velocities of components A and B agree to within \pm10 km/s, further confirming their physical association. Using the age and bolometric luminosity of CD-35 2722 B, we derive a mass of 31\pm8 Mjup from the Lyon/Dusty evolutionary models. Altogether, young late-M to mid-L type companions appear to be over-luminous for their near-IR spectral type compared to field objects, in contrast to the under-luminosity of young late-L and early-T dwarfs.

CFBDS J005910.90-011401.3: Reaching the T-Y Brown Dwarf transition?

the date of receipt and acceptance should be inserted later Abstract. We report the discovery of CFBDS J005910.90-011401.3 (hereafter CFBDS0059), the coolest brown dwarf iden- tified to date. We found CFBDS0059 using iand zimages from the Canada-France-Hawaii Telescope (CFHT), and present optical and near-infrared photometry, Keck laser guide sta r adaptive optics imaging, and a complete near-infrared spe ctrum, from 1.0 to 2.2� m. A side to side comparison of the near-infrared spectra of CFBDS0059 and ULAS J003402.77-005206.7 (hereafter ULAS0034), previously the coolest known brown dwarf, indicates that CFBDS0059 is∼ 50 ± 15K cooler. We estimate a temperature of Teff∼ 620K and gravity of log g∼ 4.75. Evolutionary models translate these parameters into an age of 1-5 Gyr and a mass of 15− 30 MJup. We estimate a photometric distance of∼13pc, which puts CFBDS0059 within easy reach of accurate parallax measurements. Its large proper m otion suggests membership in the older population of the thin disk. The spectra of both CFBDS0059 and ULAS J0034 shows probable absorption by a wide ammonia band on the blue side of the H-band flux peak. If, as we expect, that feature deepens furthe r for still lower effective temperatures, its appearance will become a natural breakpoint for the transition between the T spectr al class and the new Y spectral type. CFBDS0059 and ULAS J0034 would then be the first Y0 dwarfs.

Planet Hunters IX. KIC 8462852 - Where's the flux?

TSB acknowledges support provided through NASA grant ADAP12-0172 and ADAP14-0245. MCW and GMK acknowledge the support of the European Union through ERC grant number 279973. The authors acknowledge support from the Hungarian Research Grants OTKA K-109276, OTKA K-113117, the Lendulet-2009 and Lendulet-2012 Program (LP2012-31) of the Hungarian Academy of Sciences, the Hungarian National Research, Development and Innovation Office – NKFIH K-115709, and the ESA PECS Contract No. 4000110889/14/NL/NDe. This work was supported by the Momentum grant of the MTA CSFK Lendulet Disc Research Group. GH acknowledges support by the Polish NCN grant 2011/01/B/ST9/05448. Based on observations made with the NOT, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. This research made use of The DASCH project; we are also grateful for partial support from NSF grants AST-0407380, AST-0909073, and AST-1313370. The research leading to these results has received funding from the European Communitys Seventh Framework Programme (FP7/2007-2013) under grant agreements no. 269194 (IRSES/ASK) and no. 312844 (SPACEINN). We thank Scott Dahm, Julie Rivera, and the Keck Observatory staff for their assistance with these observations. This research was supported in part by NSF grant AST-0909222 awarded to M. Liu. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. KS gratefully acknowledges support from Swiss National Science Foundation Grant PP00P2_138979/1. HJD and DN acknowledge support by grant AYA2012-39346-C02-02 of the Spanish Secretary of State for R&D&i (MINECO). This paper makes use of data from the first public release of the WASP data (Butters et al. 2010) as provided by the WASP consortium and services at the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, and NEOWISE, which is a project of the Jet Propulsion Laboratory/California Institute of Technology. WISE and NEOWISE are funded by the National Aeronautics and Space Administration. This research made use of the SIMBAD and VIZIER Astronomical Databases, operated at CDS, Strasbourg, France (http://cdsweb.u-strasbg.fr/), and of NASAs Astrophysics Data System.

THE RISE OF SN 2014J IN THE NEARBY GALAXY M82

We report on the discovery of SN2014J in the nearby galaxy M82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova over a wide range of the electromagnetic spectrum. The first set of optical, near-IR and mid-IR observations of SN2014J, orchestrated by the intermediate Palomar Transient Factory (iPTF), show that SN2014J is a spectroscopically normal Type Ia supernova, albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the lightcurve rise. Similarly to other highly reddened Type Ia supernovae, a low value of total-to-selective extinction, Rv<2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from HST with special emphasis on the sources nearest to the SN location.We report on the discovery of SN 2014J in the nearby galaxy M82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova (SN) over a wide range of the electromagnetic spectrum. Optical, near-IR, and mid-IR observations on the rising light curve, orchestrated by the intermediate Palomar Transient Factory, show that SN 2014J is a spectroscopically normal Type Ia supernova (SN Ia), albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the light curve rise. Similar to other highly reddened SNe Ia, a low value of total-to-selective extinction, R_V ≲ 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from Hubble Space Telescope with special emphasis on the sources nearest to the SN location.

DISCOVERY OF A HIGHLY UNEQUAL-MASS BINARY T DWARF WITH KECK LASER GUIDE STAR ADAPTIVE OPTICS: A COEVALITY TEST OF SUBSTELLAR THEORETICAL MODELS AND EFFECTIVE TEMPERATURES ∗

Highly unequal-mass ratio binaries are rare among field brown dwarfs, with the mass ratio distribution of the known census described by q (4.9±0.7). However, such systems enable a unique test of the joint accuracy of evolutionary and atmospheric models, under the constraint of coevality for the individual components (the isochrone test). We carry out this test using two of the most extreme field substellar binaries currently known, the T1 + T6 Ind Bab binary and a newly discovered 014 T2.0 + T7.5 binary, 2MASS J12095613–1004008AB, identified with Keck laser guide star adaptive optics. The latter is the most extreme tight binary resolved to date (q 0.5). Based on the locations of the binary components on the Hertzsprung-Russell (H-R) diagram, current models successfully indicate that these two systems are coeval, with internal age differences of log(age) = –0.8 ± 1.3(–1.0+1.2 –1.3) dex and 0.5+0.4 –0.3(0.3+0.3 –0.4) dex for 2MASS J1209–1004AB and Ind Bab, respectively, as inferred from the Lyon (Tucson) models. However, the total mass of Ind Bab derived from the H-R diagram ( 80 M Jup using the Lyon models) is strongly discrepant with the reported dynamical mass. This problem, which is independent of the assumed age of the Ind Bab system, can be explained by a 50-100 K systematic error in the model atmosphere fitting, indicating slightly warmer temperatures for both components; bringing the mass determinations from the H-R diagram and the visual orbit into consistency leads to an inferred age of 6 Gyr for Ind Bab, older than previously assumed. Overall, the two T dwarf binaries studied here, along with recent results from T dwarfs in age and mass benchmark systems, yield evidence for small (100 K) errors in the evolutionary models and/or model atmospheres, but not significantly larger. Future parallax, resolved spectroscopy, and dynamical mass measurements for 2MASS J1209–1004AB will enable a more stringent application of the isochrone test. Finally, the binary nature of this object reduces its utility as the primary T3 near-IR spectral typing standard; we suggest SDSS J1206+2813 as a replacement.