Primeval very low-mass stars and brown dwarfs - II. The most metal-poor substellar object

NASA Astrophysics Data System (ADS)

Zhang, Z. H.; Homeier, D.; Pinfield, D. J.; Lodieu, N.; Jones, H. R. A.; Allard, F.; Pavlenko, Ya. V.

2017-06-01

SDSS J010448.46+153501.8 has previously been classified as an sdM9.5 subdwarf. However, its very blue J - K colour (-0.15 ± 0.17) suggests a much lower metallicity compared to normal sdM9.5 subdwarfs. Here, we re-classify this object as a usdL1.5 subdwarf based on a new optical and near-infrared spectrum obtained with X-shooter on the Very Large Telescope. Spectral fitting with BT-Settl models leads to Teff = 2450 ± 150 K, [Fe/H] = -2.4 ± 0.2 and log g = 5.5 ± 0.25. We estimate a mass for SDSS J010448.46+153501.8 of 0.086 ± 0.0015 M⊙ which is just below the hydrogen-burning minimum mass at [Fe/H] = -2.4 (˜0.088 M⊙) according to evolutionary models. Our analysis thus shows SDSS J010448.46+153501.8 to be the most metal-poor and highest mass substellar object known to-date. We found that SDSS J010448.46+153501.8 is joined by another five known L subdwarfs (2MASS J05325346+8246465, 2MASS J06164006-6407194, SDSS J125637.16-022452.2, ULAS J151913.03-000030.0 and 2MASS J16262034+3925190) in a 'halo brown dwarf transition zone' in the Teff-[Fe/H] plane, which represents a narrow mass range in which unsteady nuclear fusion occurs. This halo brown dwarf transition zone forms a 'substellar subdwarf gap' for mid L to early T types.

Low-mass Stellar and Substellar Companions to sdB Stars

NASA Astrophysics Data System (ADS)

Geier, S.; Classen, L.; Brünner, P.; Nagel, K.; Schaffenroth, V.; Heuser, C.; Heber, U.; Drechsel, H.; Edelmann, H.; Koen, C.; O'Toole, S. J.; Morales-Rueda, L.

2012-03-01

It has been suggested that besides stellar companions, substellar objects in close orbits may be able to trigger mass loss in a common envelope phase and form hot subdwarfs. In an ongoing project we search for close substellar companions combining time resolved high resolution spectroscopy with photometry. We determine the fraction of as yet undetected radial velocity variable systems from a sample of 27 apparently single sdB stars to be ˜eq16%. We discovered low-mass stellar companions to the He-sdB CPD-20circ 1123 and the pulsator KPD 0629-0016. The brown dwarf reported to orbit the eclipsing binary SDSS J0820+0008 could be confirmed by an analysis of high resolution spectra taken with UVES. Reflection effects have been detected in the light curves of the known sdB binaries CPD -64circ 481 and BPS CS 22169-0001. The inclinations of these systems must be much higher than expected and the most likely companion masses are in the substellar regime. Finally, we determined the orbit of the sdB binary PHL 457, which has a very small radial velocity amplitude and may host the lowest mass substellar companion known. The implications of these new results for the open question of sdB formation are discussed.

The SEEDS High-Contrast Imaging Survey of Exoplanets Around Young Stellar Objects

NASA Astrophysics Data System (ADS)

Uyama, Taichi; Hashimoto, Jun; Kuzuhara, Masayuki; Mayama, Satoshi; Akiyama, Eiji; Currie, Thayne; Livingston, John; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Abe, Lyu; Brandner, Wolfgang; Brandt, Timothy D.; Carson, Joseph C.; Egner, Sebastian; Feldt, Markus; Goto, Miwa; Grady, Carol A.; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S.; Henning, Thomas; Hodapp, Klaus W.; Ishii, Miki; Iye, Masanori; Janson, Markus; Kandori, Ryo; Knapp, Gillian R.; Kwon, Jungmi; Matsuo, Taro; Mcelwain, Michael W.; Miyama, Shoken; Morino, Jun-Ichi; Moro-Martin, Amaya; Nishimura, Tetsuo; Pyo, Tae-Soo; Serabyn, Eugene; Suenaga, Takuya; Suto, Hiroshi; Suzuki, Ryuji; Takahashi, Yasuhiro H.; Takami, Michihiro; Takato, Naruhisa; Terada, Hiroshi; Thalmann, Christian; Turner, Edwin L.; Watanabe, Makoto; Wisniewski, John; Yamada, Toru; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

2017-03-01

We present high-contrast observations of 68 young stellar objects (YSOs) that have been explored as part of the Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS) survey on the Subaru telescope. Our targets are very young (<10 Myr) stars, which often harbor protoplanetary disks where planets may be forming. We achieve a typical contrast of ˜10-4-10-5.5 at an angular distance of 1″ from the central star, corresponding to typical mass sensitivities (assuming hot-start evolutionary models) of ˜10 M J at 70 au and ˜6 M J at 140 au. We detected a new stellar companion to HIP 79462 and confirmed the substellar objects GQ Lup b and ROXs 42B b. An additional six companion candidates await follow-up observations to check for common proper motion. Our SEEDS YSO observations probe the population of planets and brown dwarfs at the very youngest ages; these may be compared to the results of surveys targeting somewhat older stars. Our sample and the associated observational results will help enable detailed statistical analyses of giant planet formation.

Moderate Resolution Spectroscopy of Substellar Companion Kappa Andromeda B

NASA Astrophysics Data System (ADS)

Wilcomb, Kielan; Konopacky, Quinn; Barman, Travis; Brown, Jessie; Brock, Laci; Macintosh, Bruce; Ruffio, Jean-Baptiste; Marois, Christian

2018-01-01

Recent direct imaging of exoplanets has revealed a population of Jupiter-like objects that orbit at large separations (~10-100 AU) from their host stars. These planets, with masses of ~2-14 MJup and temperatures of ~500-2000 K, remain a problem for the two main planet formation models—core accretion and gravitational instability. OSIRIS observations of directly imaged planets have expanded our understanding of their atmospheres, alluded to their formation, and uncovered individual molecular lines. Here, we present OSIRIS K band spectra of the “super-Jupiter,” Kappa Andromeda b. Kappa Andromeda b has a lower mass limit at the deuterium burning limit, but also has an uncertain age which may indicate the source is a higher mass brown dwarf. The spectra reveal resolved molecular lines from water and CO. We will present atmospheric properties of this object derived from comparison to PHOENIX atmosphere models, and measure a best fit C/O ratio for the source. We will compare our results to atmospheric properties of other brown dwarfs and gas giant planets in an effort to improve our knowledge of intricate atmospheres of young, substellar objects.

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

NASA Astrophysics Data System (ADS)

Wahhaj, Zahed; Liu, Michael C.; Biller, Beth A.; Clarke, Fraser; Nielsen, Eric L.; Close, Laird M.; Hayward, Thomas L.; Mamajek, Eric E.; Cushing, Michael; Dupuy, Trent; Tecza, Matthias; Thatte, Niranjan; Chun, Mark; Ftaclas, Christ; Hartung, Markus; Reid, I. Neill; Shkolnik, Evgenya L.; Alencar, Silvia H. P.; Artymowicz, Pawel; Boss, Alan; de Gouveia Dal Pino, Elisabethe; Gregorio-Hetem, Jane; Ida, Shigeru; Kuchner, Marc; Lin, Douglas N. C.; Toomey, Douglas W.

2011-03-01

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±1 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 eff= 1700-1900 K and log(g)= 4.5 ± 0.5. The spectra also show that the radial velocities of components A and B agree to within ±10 km s-1, further confirming their physical association. Using the age and bolometric luminosity of CD-35 2722 B, we derive a mass of 31 ± 8 M Jup from the Lyon/Dusty evolutionary models. Altogether, young late-M to mid-L type companions appear to be overluminous for their near-IR spectral type compared with field objects, in contrast to the underluminosity of young late-L and early-T dwarfs. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ci

VizieR Online Data Catalog: Spectroscopy of very low mass objects (Patience+, 2012)

NASA Astrophysics Data System (ADS)

Patience, J.; King, R. R.; De Rosa, R. J.; Vigan, A.; Witte, S.; Rice, E.; Helling, C.; Hauschildt, P.

2012-09-01

With a uniform VLT SINFONI data set of nine targets, we have developed an empirical grid of J, H, K spectra of the atmospheres of objects estimated to have very low substellar masses of ~5-20MJup and young ages ranging from ~1-50Myr. Most of the targets are companions, objects which are especially valuable for comparison with atmosphere and evolutionary models, as they present rare cases in which the age is accurately known from the primary. Based on the youth of the sample, all objects are expected to have low surface gravity, and this study investigates the critical early phases of the evolution of substellar objects. The spectra are compared with grids of five different theoretical atmosphere models. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************

THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Michael C.; Dupuy, Trent J.; Allers, Katelyn N., E-mail: mliu@ifa.hawaii.edu

We present a large, uniform analysis of young (≈10–150 Myr) ultracool dwarfs, based on new high-precision infrared (IR) parallaxes for 68 objects. We find that low-gravity (vl-g) late-M and L dwarfs form a continuous sequence in IR color–magnitude diagrams, separate from the field population and from current theoretical models. These vl-g objects also appear distinct from young substellar (brown dwarf and exoplanet) companions, suggesting that the two populations may have a different range of physical properties. In contrast, at the L/T transition, young, old, and spectrally peculiar objects all span a relatively narrow range in near-IR absolute magnitudes. At a given spectralmore » type, the IR absolute magnitudes of young objects can be offset from ordinary field dwarfs, with the largest offsets occurring in the Y and J bands for late-M dwarfs (brighter than the field) and mid-/late-L dwarfs (fainter than the field). Overall, low-gravity (vl-g) objects have the most uniform photometric behavior, while intermediate gravity (int-g) objects are more diverse, suggesting a third governing parameter beyond spectral type and gravity class. We examine the moving group membership for all young ultracool dwarfs with parallaxes, changing the status of 23 objects (including 8 previously identified planetary-mass candidates) and fortifying the status of another 28 objects. We use our resulting age-calibrated sample to establish empirical young isochrones and show a declining frequency of vl-g objects relative to int-g objects with increasing age. Notable individual objects in our sample include high-velocity (≳100 km s{sup −1}) int-g objects, very red late-L dwarfs with high surface gravities, candidate disk-bearing members of the MBM20 cloud and β  Pic moving group, and very young distant interlopers. Finally, we provide a comprehensive summary of the absolute magnitudes and spectral classifications of young ultracool dwarfs, using a combined sample of 102 objects

A survey for low-mass stellar and substellar members of the Hyades open cluster

NASA Astrophysics Data System (ADS)

Melnikov, Stanislav; Eislöffel, Jochen

2018-03-01

Context. Unlike young open clusters (with ages < 250 Myr), the Hyades cluster (age 600 Myr) has a clear deficit of very low-mass stars (VLM) and brown dwarfs (BD). Since this open cluster has a low stellar density and covers several tens of square degrees on the sky, extended surveys are required to improve the statistics of the VLM/BD objects in the cluster. Aim. We search for new VLM stars and BD candidates in the Hyades cluster to improve the present-day cluster mass function down to substellar masses. Methods: An imaging survey of the Hyades with a completeness limit of 21.m5 in the R band and 20.m5 in the I band was carried out with the 2k × 2k CCD Schmidt camera at the 2 m Alfred Jensch Telescope in Tautenburg. We performed a photometric selection of the cluster member candidates by combining results of our survey with 2MASS JHKs photometry Results: We present a photometric and proper motion survey covering 23.4 deg2 in the Hyades cluster core region. Using optical/IR colour-magnitude diagrams, we identify 66 photometric cluster member candidates in the magnitude range 14.m7 < I < 20.m5. The proper motion measurements are based on several all-sky surveys with an epoch difference of 60-70 yr for the bright objects. The proper motions allowed us to discriminate the cluster members from field objects and resulted in 14 proper motion members of the Hyades. We rediscover Hy 6 as a proper motion member and classify it as a substellar object candidate (BD) based on the comparison of the observed colour-magnitude diagram with theoretical model isochrones. Conclusions: With our results, the mass function of the Hyades continues to be shallow below 0.15 M⊙ indicating that the Hyades have probably lost their lowest mass members by means of dynamical evolution. We conclude that the Hyades core represents the "VLM/BD desert" and that most of the substeller objects may have already left the volume of the cluster.

Galactic Stellar and Substellar Initial Mass Function

NASA Astrophysics Data System (ADS)

Chabrier, Gilles

2003-07-01

We review recent determinations of the present-day mass function (PDMF) and initial mass function (IMF) in various components of the Galaxy-disk, spheroid, young, and globular clusters-and in conditions characteristic of early star formation. As a general feature, the IMF is found to depend weakly on the environment and to be well described by a power-law form for m>~1 Msolar and a lognormal form below, except possibly for early star formation conditions. The disk IMF for single objects has a characteristic mass around mc~0.08 Msolar and a variance in logarithmic mass σ~0.7, whereas the IMF for multiple systems has mc~0.2 Msolar and σ~0.6. The extension of the single MF into the brown dwarf regime is in good agreement with present estimates of L- and T-dwarf densities and yields a disk brown dwarf number density comparable to the stellar one, nBD~n*~0.1 pc-3. The IMF of young clusters is found to be consistent with the disk field IMF, providing the same correction for unresolved binaries, confirming the fact that young star clusters and disk field stars represent the same stellar population. Dynamical effects, yielding depletion of the lowest mass objects, are found to become consequential for ages >~130 Myr. The spheroid IMF relies on much less robust grounds. The large metallicity spread in the local subdwarf photometric sample, in particular, remains puzzling. Recent observations suggest that there is a continuous kinematic shear between the thick-disk population, present in local samples, and the genuine spheroid one. This enables us to derive only an upper limit for the spheroid mass density and IMF. Within all the uncertainties, the latter is found to be similar to the one derived for globular clusters and is well represented also by a lognormal form with a characteristic mass slightly larger than for the disk, mc~0.2-0.3 Msolar, excluding a significant population of brown dwarfs in globular clusters and in the spheroid. The IMF characteristic of early star

A HST/WFC3 Search for Substellar Companions in the Orion Nebula Cluster

NASA Astrophysics Data System (ADS)

Strampelli, Giovanni Maria; Aguilar, Jonathan; Aparicio, Antonio; Piotto, Giampaolo; Pueyo, Laurent; Robberto, Massimo

2018-01-01

We present new results relative to the population of substellar binaries in the Orion Nebula Cluster. We reprocessed HST/WFC3 data using an analysis technique developed to detect close companions in the wings of the stellar PSFs, based on the PyKLIP implementation of the KLIP PSF subtraction algorithm. Starting from a sample of ~1200 stars selected over the range J=11-15 mag, we were able to uncover ~80 candidate companions in the magnitude range J=16-23 mag. We use the presence of the 1.4 micron H2O absorption feature in the companion photosphere to discriminate 32 bona-fide substellar candidates from a population of reddened background objects. We derive an estimate of the companion mass assuming a 2Myr isochrone and the reddening of their primary. With 8 stellar companions, 19 brown dwarfs and 5 planetary mass objects, our study provide us with an unbiased sample of companions at the low-mass end of the IMF, probing the transition from binary to planetary systems.

Sedimentation Efficiency of Condensation Clouds in Substellar Atmospheres

NASA Astrophysics Data System (ADS)

Gao, Peter; Marley, Mark S.; Ackerman, Andrew S.

2018-03-01

Condensation clouds in substellar atmospheres have been widely inferred from spectra and photometric variability. Up until now, their horizontally averaged vertical distribution and mean particle size have been largely characterized using models, one of which is the eddy diffusion–sedimentation model from Ackerman and Marley that relies on a sedimentation efficiency parameter, f sed, to determine the vertical extent of clouds in the atmosphere. However, the physical processes controlling the vertical structure of clouds in substellar atmospheres are not well understood. In this work, we derive trends in f sed across a large range of eddy diffusivities (K zz ), gravities, material properties, and cloud formation pathways by fitting cloud distributions calculated by a more detailed cloud microphysics model. We find that f sed is dependent on K zz , but not gravity, when K zz is held constant. f sed is most sensitive to the nucleation rate of cloud particles, as determined by material properties like surface energy and molecular weight. High surface energy materials form fewer, larger cloud particles, leading to large f sed (>1), and vice versa for materials with low surface energy. For cloud formation via heterogeneous nucleation, f sed is sensitive to the condensation nuclei flux and radius, connecting cloud formation in substellar atmospheres to the objects’ formation environments and other atmospheric aerosols. These insights could lead to improved cloud models that help us better understand substellar atmospheres. For example, we demonstrate that f sed could increase with increasing cloud base depth in an atmosphere, shedding light on the nature of the brown dwarf L/T transition.

Constraining Substellar Magnetic Dynamos using Brown Dwarf Radio Aurorae

NASA Astrophysics Data System (ADS)

Kao, Melodie Minyu

Brown dwarfs share characteristics with both low-mass stars and gas giant planets, making them useful laboratories for studying physics occurring in objects throughout this low mass and temperature range. Of particular interest in this dissertation is the nature of the engine driving their magnetic fields. Fully convective magnetic dynamos can operate in low mass stars, brown dwarfs, gas giant planets, and even fluid metal cores in small rocky planets. Objects in this wide mass range are capable of hosting strong magnetic fields, which shape much of the evolution of planets and stars: strong fields can protect planetary atmospheres from evaporating, generate optical and infrared emission that masquerade as clouds in the atmospheres of other worlds, and affect planet formation mechanisms. Thus, implications from understanding convective dynamo mechanisms also extend to exoplanet habitability. How the convective dynamos driving these fields operate remains an important open problem. While we have extensive data to inform models of magnetic dynamo mechanisms in higher mass stars like our Sun, the coolest and lowest-mass objects that probe the substellar-planetary boundary do not possess the internal structures necessary to drive solar-type dynamos. A number of models examining fully convective dynamo mechanisms have been proposed but they remain unconstrained by magnetic field measurements in the lowest end of the substellar mass and temperature space. Detections of highly circularly polarized pulsed radio emission provide our only window into magnetic field measurements for objects in the ultracool brown dwarf regime, but these detections are very rare; until this dissertation, only one attempt out of 60 had been successful. The work presented in this dissertation seeks to address this problem and examines radio emission from late L, T, and Y spectral type brown dwarfs spanning 1-6 times the surface temperature of Earth and explores implications for fully convective

A Test of Pre-Main-Sequence Evolutionary Models across the Stellar/Substellar Boundary Based on Spectra of the Young Quadruple GG Tauri

NASA Astrophysics Data System (ADS)

White, Russel J.; Ghez, A. M.; Reid, I. Neill; Schultz, Greg

1999-08-01

We present spatially separated optical spectra of the components of the young hierarchical quadruple GG Tau. Spectra of GG Tau Aa and Ab (separation 0.25"~35 AU) were obtained with the Faint Object Spectrograph on board the Hubble Space Telescope. Spectra of GG Tau Ba and Bb (separation 1.48"~207 AU) were obtained with both the HIRES and the LRIS spectrographs on the W. M. Keck telescopes. The components of this minicluster, which span a wide range in spectral type (K7-M7), are used to test both evolutionary models and the temperature scale for very young, low-mass stars under the assumption of coeval formation. Of the evolutionary models tested, those of Baraffe et al. yield the most consistent ages when combined with a temperature scale intermediate between that of dwarfs and giants. The version of the Baraffe et al. models computed with a mixing length nearly twice the pressure scale height is of particular interest, as it predicts masses for GG Tau Aa and Ab that are in agreement with their dynamical mass estimate. Using this evolutionary model and a coeval (at 1.5 Myr) temperature scale, we find that the coldest component of the GG Tau system, GG Tau Bb, is substellar with a mass of 0.044+/-0.006 Msolar. This brown dwarf companion is especially intriguing as it shows signatures of accretion, although this accretion is not likely to alter its mass significantly. GG Tau Bb is currently the lowest mass, spectroscopically confirmed companion to a T Tauri star, and is one of the coldest, lowest mass T Tauri objects in the Taurus-Auriga star-forming region. Based partly on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

SOAR Adaptive Optics Observations of Young Stellar Objects

NASA Astrophysics Data System (ADS)

Briceno, Cesar

2018-01-01

I present results from recent studies of nearby star-forming regions using the SOAR 4.1m telescope Ground-layer Adaptive Optics system.Using narrow-band Hα and [SII] imaging we discovered a spectacular extended Herbig-Haro jet powered by a 26 MJup young brown dwarf located in the vicinity of the σ Orionis cluster. The collimated structure of multiple knots spans 0.26 pc, making it a scaled down version of the parsec-length jets seen in T Tauri stars, and the first substellar analog of an HH jet system.In the ε Chamaeleon stellar group we carried out an Adaptive Optics-aided speckle imaging study of 47 members and candidate members, to characterize the multiplicity of this, one of the nearest groups of young (~3-5 Myr) stars. We resolved 10 new binary pairs, 5 previously know binaries and two triple systems. We find a companion frequency of 0.010±0.04 per decade of separation, in the 4 to 300 AU separation range, a result comparable to main sequence dwarfs in the field. However, the more massive association members, with B and A spectral types, all have companions in this separation range. Finally, we provide new constraints on the orbital elements of the ε Cha triple system.

Early phases in the stellar and substellar formation and evolution. Infrared and submillimeter data in the Barnard 30 dark cloud

NASA Astrophysics Data System (ADS)

Barrado, D.; de Gregorio Monsalvo, I.; Huélamo, N.; Morales-Calderón, M.; Bayo, A.; Palau, A.; Ruiz, M. T.; Rivière-Marichalar, P.; Bouy, H.; Morata, Ó.; Stauffer, J. R.; Eiroa, C.; Noriega-Crespo, A.

2018-04-01

Aims: The early evolutionary stage of brown dwarfs (BDs) is not very well characterized, especially during the embedded phase. Our goal is to gain insight into the dominant formation mechanism of very low-mass objects and BDs. Methods: We have conducted deep observations at 870 μm obtained with the LABOCA bolometer at the APEX telescope in order to identify young submillimeter (submm) sources in the Barnard 30 dark cloud. We have complemented these data with multi-wavelength observations from the optical to the far-IR and compiled complete spectral energy distributions in order to identify the counterparts, characterize the sources and to assess their membership to the association and stellar or substellar status based on the available photometric information. Results: We have identified 34 submm sources and a substantial number of possible and probable Barnard 30 members within each individual APEX/LABOCA beam. They can be classified into three distinct groups. First, 15 of these 34 have a clear optical or IR counterpart to the submm peak and nine of them are potential proto-BD candidates. Moreover, a substantial number of them could be multiple systems. A second group of 13 sources comprises candidate members with significant infrared excesses located away from the central submm emission. All of them include BD candidates, some displaying IR excess, but their association with submm emission is unclear. In addition, we have found six starless cores and, based on the total dust mass estimate, three might be pre-substellar (or pre-BDs) cores. Finally, the complete characterization of our APEX/LABOCA sources, focusing on those detected at 24 and/or 70 μm, indicates that in our sample of 34 submm sources there are, at least: two WTTs, four CTTs, five young stellar objects, eight proto-BD candidates (with another three dubious cases), and one very low luminosity objects. Conclusions: Our findings provide additional evidence concerning the BD formation mechanism

A Search for Water Maser Emission from Brown Dwarfs and Low-luminosity Young Stellar Objects

NASA Astrophysics Data System (ADS)

Gómez, José F.; Palau, Aina; Uscanga, Lucero; Manjarrez, Guillermo; Barrado, David

2017-05-01

We present a survey for water maser emission toward a sample of 44 low-luminosity young objects, comprising (proto-)brown dwarfs, first hydrostatic cores (FHCs), and other young stellar objects (YSOs) with bolometric luminosities lower than 0.4 L ⊙. Water maser emission is a good tracer of energetic processes, such as mass-loss and/or accretion, and is a useful tool to study these processes with very high angular resolution. This type of emission has been confirmed in objects with L bol ≳ 1 L ⊙. Objects with lower luminosities also undergo mass-loss and accretion, and thus, are prospective sites of maser emission. Our sensitive single-dish observations provided a single detection when pointing toward the FHC L1448 IRS 2E. However, follow-up interferometric observations showed water maser emission associated with the nearby YSO L1448 IRS 2 (a Class 0 protostar of L bol ≃ 3.6-5.3 L ⊙) and did not find any emission toward L1448 IRS 2E. The upper limits for water maser emission determined by our observations are one order of magnitude lower than expected from the correlation between water maser luminosities and bolometric luminosities found for YSOs. This suggests that this correlation does not hold at the lower end of the (sub)stellar mass spectrum. Possible reasons are that the slope of this correlation is steeper at L bol ≤ 1 L ⊙ or that there is an absolute luminosity threshold below which water maser emission cannot be produced. Alternatively, if the correlation still stands at low luminosity, the detection rates of masers would be significantly lower than the values obtained in higher-luminosity Class 0 protostars.

A Search for Water Maser Emission from Brown Dwarfs and Low-luminosity Young Stellar Objects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gómez, José F.; Manjarrez, Guillermo; Palau, Aina

We present a survey for water maser emission toward a sample of 44 low-luminosity young objects, comprising (proto-)brown dwarfs, first hydrostatic cores (FHCs), and other young stellar objects (YSOs) with bolometric luminosities lower than 0.4 L {sub ⊙}. Water maser emission is a good tracer of energetic processes, such as mass-loss and/or accretion, and is a useful tool to study these processes with very high angular resolution. This type of emission has been confirmed in objects with L {sub bol} ≳ 1 L {sub ⊙}. Objects with lower luminosities also undergo mass-loss and accretion, and thus, are prospective sites of maser emission.more » Our sensitive single-dish observations provided a single detection when pointing toward the FHC L1448 IRS 2E. However, follow-up interferometric observations showed water maser emission associated with the nearby YSO L1448 IRS 2 (a Class 0 protostar of L {sub bol} ≃ 3.6–5.3 L {sub ⊙}) and did not find any emission toward L1448 IRS 2E. The upper limits for water maser emission determined by our observations are one order of magnitude lower than expected from the correlation between water maser luminosities and bolometric luminosities found for YSOs. This suggests that this correlation does not hold at the lower end of the (sub)stellar mass spectrum. Possible reasons are that the slope of this correlation is steeper at L {sub bol} ≤ 1 L {sub ⊙} or that there is an absolute luminosity threshold below which water maser emission cannot be produced. Alternatively, if the correlation still stands at low luminosity, the detection rates of masers would be significantly lower than the values obtained in higher-luminosity Class 0 protostars.« less

Direct evidence of a sub-stellar companion around CT Chamaeleontis

NASA Astrophysics Data System (ADS)

Schmidt, T. O. B.; Neuhäuser, R.; Seifahrt, A.; Vogt, N.; Bedalov, A.; Helling, Ch.; Witte, S.; Hauschildt, P. H.

2008-11-01

Aims: In our ongoing search for close and faint companions around T Tauri stars in the Chamaeleon star-forming region, we here present observations of a new common proper motion companion to the young T-Tauri star and Chamaeleon member CT Cha and discuss its properties in comparison to other young, low-mass objects and to synthetic model spectra from different origins. Methods: Common proper motion of the companion and CT Cha was confirmed by direct Ks-band imaging data taken with the VLT Adaptive Optics (AO) instrument NACO in February 2006 and March 2007, together with a Hipparcos binary for astrometric calibration. An additional J-band image was taken in March 2007 to obtain color information for a first classification of the companion. Moreover, AO integral field spectroscopy with SINFONI in J, and H+K bands was obtained to deduce physical parameters of the companion, such as temperature and extinction. Relative flux calibration of the bands was achieved using photometry from the NACO imaging data. Results: We found a very faint (Ks = 14.9 mag, Ks0 = 14.4 mag) object, just ~2.67´´ northwest of CT Cha corresponding to a projected separation of ~440 AU at 165 ± 30 pc. We show that CT Cha A and this faint object form a common proper motion pair and that the companion is by ≥4σ significance not a stationary background object. The near-infrared spectroscopy yields a temperature of 2600 ± 250 K for the companion and an optical extinction of AV = 5.2 ± 0.8 mag, when compared to spectra calculated from Drift-Phoenix model atmospheres. We demonstrate the validity of the model fits by comparison to several other well-known young sub-stellar objects. Conclusions: We conclude that the CT Cha companion is a very low-mass member of Chamaeleon and very likely a physical companion to CT Cha, as the probability for a by chance alignment is ≤0.01. Due to a prominent Pa-β emission in the J-band, accretion is probably still ongoing onto the CT Cha companion. From

A SUBSTELLAR COMPANION TO THE DUSTY PLEIADES STAR HD 23514

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, David R.; Zuckerman, B.; Marois, Christian

2012-03-20

With adaptive optics imaging at Keck observatory, we have discovered a substellar companion to the F6 Pleiades star HD 23514, one of the dustiest main-sequence stars known to date (L{sub IR}/L{sub *} {approx} 2%). This is one of the first brown dwarfs discovered as a companion to a star in the Pleiades. The 0.06 M{sub Sun} late-M secondary has a projected separation of {approx}360 AU. The scarcity of substellar companions to stellar primaries in the Pleiades combined with the extremely dusty environment make this a unique system to study.

The Influence of a Substellar Continent on the Climate of a Tidally Locked Exoplanet

NASA Astrophysics Data System (ADS)

Lewis, Neil T.; Lambert, F. Hugo; Boutle, Ian A.; Mayne, Nathan J.; Manners, James; Acreman, David M.

2018-02-01

Previous studies have demonstrated that continental carbon-silicate weathering is important to the continued habitability of a terrestrial planet. Despite this, few studies have considered the influence of land on the climate of a tidally locked planet. In this work we use the Met Office Unified Model, coupled to a land-surface model, to investigate the climate effects of a continent located at the substellar point. We choose to use the orbital and planetary parameters of Proxima Centauri B as a template, to allow comparison with the work of others. A region of the surface where T s > 273.15 K is always retained, and previous conclusions on the habitability of Proxima Centauri B remain intact. We find that substellar land causes global cooling and increases day–night temperature contrasts by limiting heat redistribution. Furthermore, we find that substellar land is able to introduce a regime change in the atmospheric circulation. Specifically, when a continent offset to the east of the substellar point is introduced, we observe the formation of two mid-latitude counterrotating jets, and a substantially weakened equatorial superrotating jet.

Why Compositional Convection Cannot Explain Substellar Objects’ Sharp Spectral-type Transitions

NASA Astrophysics Data System (ADS)

Leconte, Jérémy

2018-02-01

As brown dwarfs and young giant planets cool down, they are known to experience various chemical transitions—for example, from {CO} rich L-dwarfs to methane rich T-dwarfs. Those chemical transitions are accompanied by spectral transitions with sharpness that cannot be explained by chemistry alone. In a series of articles, Tremblin et al. proposed that some of the yet-unexplained features associated with these transitions could be explained by a reduction of the thermal gradient near the photosphere. To explain, in turn, this more isothermal profile, they invoke the presence of an instability analogous to fingering convection—compositional convection—triggered by the change in mean molecular weight of the gas due to the chemical transitions mentioned above. In this Letter, we use existing arguments to demonstrate that any turbulent transport, if present, would in fact increase the thermal gradient. This misinterpretation comes from the fact that turbulence mixes/homogenizes entropy (potential temperature) instead of temperature. So, while increasing transport, turbulence in an initially stratified atmosphere actually carries energy downward, whether it is due to fingering or any other type of compositional convection. These processes therefore cannot explain the features observed along the aforementioned transitions by reducing the thermal gradient in the atmosphere of substellar objects. Understanding the microphysical and dynamical properties of clouds at these transitions thus probably remains our best way forward.

The Impact of Clouds and Hazes in Substellar Atmospheres

NASA Astrophysics Data System (ADS)

Morley, Caroline; Fortney, Jonathan J.; Marley, Mark S.

2016-01-01

The formation of clouds significantly alters the spectra of cool substellar atmospheres from terrestrial planets to brown dwarfs. In cool planets like Earth and Jupiter, volatile species like water and ammonia condense to form ice clouds. In hot planets and brown dwarfs, iron and silicates instead condense, forming dusty clouds. Irradiated methane-rich planets may have substantial hydrocarbon hazes. During my thesis, I have studied the impact of clouds and hazes in a variety of substellar objects. First, I present results for cool brown dwarfs including clouds previously neglected in model atmospheres. Model spectra that include sulfide and salt clouds can match the spectra of T dwarf atmospheres; water ice clouds will alter the spectra of the newest and coldest brown dwarfs, the Y dwarfs. These sulfide/salt and ice clouds potentially drive spectroscopic variability in these cool objects, and this variability should be distinguishable from variability caused by hot spots.Next, I present results for small, cool exoplanets between the size of Earth and Neptune, so-called super Earths. They likely have sulfide and salt clouds and also have photochemical hazes caused by stellar irradiation. Vast resources have been dedicated to characterizing the handful of super Earths accessible to current telescopes, yet of the planets smaller than Neptune studied to date, all have radii in the near-infrared consistent with being constant in wavelength, likely showing that these small planets are consistently enshrouded in thick hazes and clouds. Very thick, lofted clouds of salts or sulfides in high metallicity (1000× solar) atmospheres create featureless transmission spectra in the near-infrared. Photochemical hazes with a range of particle sizes also create featureless transmission spectra at lower metallicities. I show that despite these challenges, there are promising avenues for understanding this class of small planets: by observing the thermal emission and reflectivity of

Dust cloud evolution in sub-stellar atmospheres via plasma deposition and plasma sputtering

NASA Astrophysics Data System (ADS)

Stark, C. R.; Diver, D. A.

2018-04-01

Context. In contemporary sub-stellar model atmospheres, dust growth occurs through neutral gas-phase surface chemistry. Recently, there has been a growing body of theoretical and observational evidence suggesting that ionisation processes can also occur. As a result, atmospheres are populated by regions composed of plasma, gas and dust, and the consequent influence of plasma processes on dust evolution is enhanced. Aim. This paper aims to introduce a new model of dust growth and destruction in sub-stellar atmospheres via plasma deposition and plasma sputtering. Methods: Using example sub-stellar atmospheres from DRIFT-PHOENIX, we have compared plasma deposition and sputtering timescales to those from neutral gas-phase surface chemistry to ascertain their regimes of influence. We calculated the plasma sputtering yield and discuss the circumstances where plasma sputtering dominates over deposition. Results: Within the highest dust density cloud regions, plasma deposition and sputtering dominates over neutral gas-phase surface chemistry if the degree of ionisation is ≳10-4. Loosely bound grains with surface binding energies of the order of 0.1-1 eV are susceptible to destruction through plasma sputtering for feasible degrees of ionisation and electron temperatures; whereas, strong crystalline grains with binding energies of the order 10 eV are resistant to sputtering. Conclusions: The mathematical framework outlined sets the foundation for the inclusion of plasma deposition and plasma sputtering in global dust cloud formation models of sub-stellar atmospheres.

The Taurus Boundary of Stellar/Substellar (TBOSS) Survey. II. Disk Masses from ALMA Continuum Observations

NASA Astrophysics Data System (ADS)

Ward-Duong, K.; Patience, J.; Bulger, J.; van der Plas, G.; Ménard, F.; Pinte, C.; Jackson, A. P.; Bryden, G.; Turner, N. J.; Harvey, P.; Hales, A.; De Rosa, R. J.

2018-02-01

We report 885 μm ALMA continuum flux densities for 24 Taurus members spanning the stellar/substellar boundary with spectral types from M4 to M7.75. Of the 24 systems, 22 are detected at levels ranging from 1.0 to 55.7 mJy. The two nondetections are transition disks, though other transition disks in the sample are detected. Converting ALMA continuum measurements to masses using standard scaling laws and radiative transfer modeling yields dust mass estimates ranging from ∼0.3 to 20 M ⊕. The dust mass shows a declining trend with central object mass when combined with results from submillimeter surveys of more massive Taurus members. The substellar disks appear as part of a continuous sequence and not a distinct population. Compared to older Upper Sco members with similar masses across the substellar limit, the Taurus disks are brighter and more massive. Both Taurus and Upper Sco populations are consistent with an approximately linear relationship in M dust to M star, although derived power-law slopes depend strongly upon choices of stellar evolutionary model and dust temperature relation. The median disk around early-M stars in Taurus contains a comparable amount of mass in small solids as the average amount of heavy elements in Kepler planetary systems on short-period orbits around M-dwarf stars, with an order of magnitude spread in disk dust mass about the median value. Assuming a gas-to-dust ratio of 100:1, only a small number of low-mass stars and brown dwarfs have a total disk mass amenable to giant planet formation, consistent with the low frequency of giant planets orbiting M dwarfs.

Low mass companions to nearby stars: Spectral classification and its relation to the stellar/substellar break

NASA Technical Reports Server (NTRS)

Kirkpatrick, J. Davy; Mccarthy, Donald W., Jr.

1994-01-01

The relationship between mass and spectral class for main-sequence stars has never been obtained for dwarfs cooler than M6; currently, the true nature of objects classified as M7, M8, M9, or later (be they stellar or substellar) is not known. In this paper, spectral types for the components in five low mass binary systems are estimated based on previously published infrared speckle measurements, red/infrared photometry, and parallax data, together with newly acquired high signal-to-noise composite spectra of the systems and revised magnitude difference relations for M dwarfs. For two of these binaries, the secondary has a smaller mass (less than 0.09 solar mass) than any object having a dynamically measured mass and a known spectral type, thus extending the spectral class/mass relation to lower masses than has previously been possible. Data from the higher mass components (0.09 solar mass less than M less than 0.40 solar mass) are consistent with earlier results; the two lowest mass objects -- though having mass errors which could place them on either side of the M dwarf/brown dwarf dividing line (Mass is about 0.08 solar mass) -- are found to have spectral types no cooler than M6.5 V. An extrapolation of the updated spectral class/mass relation to the hydrogen-burning limit suggests that objects of type M7 and later may be substellar. Direct confirmation of this awaits the discovery of a close, very late-type binary for which dynamical masses can be measured.

Update on ONC's Substellar IMF: A Second Peak in the Brown Dwarf Regime

NASA Astrophysics Data System (ADS)

Drass, Holger; Bayo, A.; Chini, R.; Haas, M.

2017-06-01

The Orion Nebular Cluster (ONC) has become the prototype cluster for studying the Initial Mass Function (IMF). In a deep JHK survey of the ONC with HAWK-I we detected a large population of 900 Brown Dwarfs and Planetary Mass Object candidates presenting a pronounced second peak in the substellar IMF. One of the most obvious issues of this result is the verification of cluster membership. The analysis so far was mainly based on statistical consideration. In this presentation I will show the results from using different high-resolution extinction map to determine the ONC membership.

A SUBSTELLAR COMMON PROPER-MOTION COMPANION TO THE PLEIAD H II 1348

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geissler, Kerstin; Metchev, Stanimir A.; Pham, Alfonse

2012-02-10

We announce the identification of a proper-motion companion to the star H II 1348, a K5 V member of the Pleiades open cluster. The existence of a faint point source 1.''1 away from H II 1348 was previously known from adaptive optics imaging by Bouvier et al. However, because of a high likelihood of background star contamination and in the absence of follow-up astrometry, Bouvier et al. tentatively concluded that the candidate companion was not physically associated with H II 1348. We establish the proper-motion association of the pair from adaptive optics imaging with the Palomar 5 m telescope. Adaptivemore » optics spectroscopy with the integral field spectrograph OSIRIS on the Keck 10 m telescope reveals that the companion has a spectral type of M8 {+-} 1. According to substellar evolution models, the M8 spectral type resides within the substellar mass regime at the age of the Pleiades. The primary itself is a known double-lined spectroscopic binary, which makes the resolved companion, H II 1348B, the least massive and widest component of this hierarchical triple system and the first substellar companion to a stellar primary in the Pleiades.« less

Optical and Near-infrared Spectra of σ Orionis Isolated Planetary-mass Objects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zapatero Osorio, M. R.; Béjar, V. J. S.; Ramírez, K. Peña, E-mail: mosorio@cab.inta-csic.es, E-mail: vbejar@iac.es, E-mail: karla.pena@uantof.cl

We have obtained low-resolution optical (0.7–0.98 μ m) and near-infrared (1.11–1.34 μ m and 0.8–2.5 μ m) spectra of 12 isolated planetary-mass candidates ( J = 18.2–19.9 mag) of the 3 Myr σ Orionis star cluster with the aim of determining the spectroscopic properties of very young, substellar dwarfs and assembling a complete cluster mass function. We have classified our targets by visual comparison with high- and low-gravity standards and by measuring newly defined spectroscopic indices. We derived L0–L4.5 and M9–L2.5 using high- and low-gravity standards, respectively. Our targets reveal clear signposts of youth, thus corroborating their cluster membership andmore » planetary masses (6–13 M {sub Jup}). These observations complete the σ Orionis mass function by spectroscopically confirming the planetary-mass domain to a confidence level of ∼75%. The comparison of our spectra with BT-Settl solar metallicity model atmospheres yields a temperature scale of 2350–1800 K and a low surface gravity of log g ≈ 4.0 [cm s{sup −2}], as would be expected for young planetary-mass objects. We discuss the properties of the cluster’s least-massive population as a function of spectral type. We have also obtained the first optical spectrum of S Ori 70, a T dwarf in the direction of σ Orionis. Our data provide reference optical and near-infrared spectra of very young L dwarfs and a mass function that may be used as templates for future studies of low-mass substellar objects and exoplanets. The extrapolation of the σ Orionis mass function to the solar neighborhood may indicate that isolated planetary-mass objects with temperatures of ∼200–300 K and masses in the interval 6–13 M {sub Jup} may be as numerous as very low-mass stars.« less

Exploring Substellar Evolution with the Coldest Brown Dwarfs

NASA Astrophysics Data System (ADS)

Dupuy, Trent J.

2017-01-01

The coldest brown dwarfs are our best analogs to extrasolar gas-giant planets, representing the lowest mass products of star formation. Our view of such objects has been transformed over the last few years as new observations have revealed that the solar neighborhood is populated by much colder objects than previously recognized. At the center of efforts to discover and characterize these coldest substellar objects have been observations from NASA missions (WISE, Spitzer, HST) and the Keck Telescopes. I will review the tremendous progress made in this field over just the last few years thanks to major community efforts to overcome observational challenges in obtaining spectroscopy, photometry, and astrometry of these infrared-faint, optically invisible objects. Spectra from HST and Keck were key in establishing the much anticipated "Y" spectral type, extending the classic stellar classification scheme to atmospheres as cool as 300-400 K. Parallaxes and photometry from Spitzer and Keck have provided absolute fluxes, enabling robust temperature determinations and critical tests of model atmopheres. High-resolution imaging with Keck laser guide star adaptive optics (LGS AO) has been the most prolific resource for revealing tight companions among the coldest brown dwarfs. In fact, with continued orbit monitoring with Keck LGS AO and HST, these binary systems will ultimately provide dynamical masses that will allow the strongest tests of models and reveal if the coldest brown dwarfs are indeed "planetary mass" (less than about 13 Jupiter masses) as is currently thought.

New Evidence for a Substellar Luminosity Problem: Dynamical Mass for the Brown Dwarf Binary Gl 417BC

NASA Astrophysics Data System (ADS)

Dupuy, Trent J.; Liu, Michael C.; Ireland, Michael J.

2014-08-01

We present new evidence for a problem with cooling rates predicted by substellar evolutionary models that implies that model-derived masses in the literature for brown dwarfs and directly imaged planets may be too high. Based on our dynamical mass for Gl 417BC (L4.5+L6) and a gyrochronology system age from its young, solar-type host star, commonly used models predict luminosities 0.2-0.4 dex lower than we observe. This corroborates a similar luminosity-age discrepancy identified in our previous work on the L4+L4 binary HD 130948BC, which coincidentally has nearly identical component masses (≈50-55 M Jup) and age (≈800 Myr) as Gl 417BC. Such a luminosity offset would cause systematic errors of 15%-25% in model-derived masses at this age. After comparing different models, including cloudless models that should not be appropriate for mid-L dwarfs like Gl 417BC and HD 130948BC but actually match their luminosities better, we speculate the observed overluminosity could be caused by opacity holes (i.e., patchy clouds) in these objects. Moreover, from hybrid substellar evolutionary models that account for cloud disappearance, we infer the corresponding phase of overluminosity may extend from a few hundred million years up to a few gigayears and cause masses to be overestimated by up to 25%, even well after clouds disappear from view entirely. Thus, the range of ages and spectral types affected by this potential systematic shift in luminosity evolution would encompass most known directly imaged gas-giants and field brown dwarfs. Data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

From Stars to Super-Planets: The Low-Mass IMF in the Young Cluster IC348

NASA Technical Reports Server (NTRS)

Najita, Joan R.; Tiede, Glenn P.; Carr, John S.

2000-01-01

We investigate the low-mass population of the young cluster IC348 down to the deuterium-burning limit, a fiducial boundary between brown dwarf and planetary mass objects, using a new and innovative method for the spectral classification of late-type objects. Using photometric indices, constructed from HST/NICMOS narrow-band imaging, that measure the strength of the 1.9 micron water band, we determine the spectral type and reddening for every M-type star in the field, thereby separating cluster members from the interloper population. Due to the efficiency of our spectral classification technique, our study is complete from approximately 0.7 solar mass to 0.015 solar mass. The mass function derived for the cluster in this interval, dN/d log M alpha M(sup 0.5), is similar to that obtained for the Pleiades, but appears significantly more abundant in brown dwarfs than the mass function for companions to nearby sun-like stars. This provides compelling observational evidence for different formation and evolutionary histories for substellar objects formed in isolation vs. as companions. Because our determination of the IMF is complete to very low masses, we can place interesting constraints on the role of physical processes such as fragmentation in the star and planet formation process and the fraction of dark matter in the Galactic halo that resides in substellar objects.

BROWN DWARFS IN YOUNG MOVING GROUPS FROM PAN-STARRS1. I. AB DORADUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aller, Kimberly M.; Liu, Michael C.; Magnier, Eugene A.

Substellar members of young (≲150 Myr) moving groups are valuable benchmarks to empirically define brown dwarf evolution with age and to study the low-mass end of the initial mass function. We have combined Pan-STARRS1 (PS1) proper motions with optical–IR photometry from PS1, Two Micron All Sky Survey (2MASS), and WISE to search for substellar members of the AB Dor Moving Group within ≈50 pc and with spectral types of late M to early L, corresponding to masses down to ≈30 M {sub Jup} at the age of the group (≈125 Myr). Including both photometry and proper motions allows us tomore » better select candidates by excluding field dwarfs whose colors are similar to young AB Dor Moving Group members. Our near-IR spectroscopy has identified six ultracool dwarfs (M6–L4; ≈30–100 M {sub Jup}) with intermediate surface gravities (int-g) as candidate members of the AB Dor Moving Group. We find another two candidate members with spectra showing hints of youth but consistent with field gravities. We also find four field brown dwarfs unassociated with the AB Dor Moving Group, three of which have int-g gravity classification. While signatures of youth are present in the spectra of our ≈125 Myr objects, neither their J – K nor W 1 – W 2 colors are significantly redder than field dwarfs with the same spectral types, unlike younger ultracool dwarfs. We also determined PS1 parallaxes for eight of our candidates and one previously identified AB Dor Moving Group candidate. Although radial velocities (and parallaxes, for some) are still needed to fully assess membership, these new objects provide valuable insight into the spectral characteristics and evolution of young brown dwarfs.« less

The BANYAN-Sigma Bayesian classifier and the search for isolated planetary-mass objects

NASA Astrophysics Data System (ADS)

Gagné, Jonathan

2018-01-01

I will present new developments in the construction of a Bayesian classification tool to identify members of 22 young associations within 150 pc from partially complete kinematic data sets such as Gaia-DR1 and DR2. The new BANYAN-Sigma tool makes it possible to quickly analyze massive data sets and yields a better classification performance than all its predecessors. It will open the door to large-scale surveys to complete the stellar and substellar populations of nearby associations, which will provide deep insights in the low-mass end of the initial mass function and valuable age-calibrated targets for exoplanet surveys.I will also presents preliminary results of a search for T-type isolated planetary-mass objects in these young associations, based on BANYAN-Sigma and a cross-match between the AllWISE and 2MASS-Reject catalogs.

Mapping the Substellar Mass-Luminosity Relation Down to the L/T Transition

NASA Astrophysics Data System (ADS)

Dupuy, Trent

2016-10-01

Substellar models underpin our theoretical understanding of brown dwarfs and gas-giant exoplanets, so assessing their accuracy is paramount. The past several years have seen progress in testing models thanks to a growing number of dynamical (total) masses for brown dwarf binaries determined via (relative) orbit monitoring from ground-based AO. However, the strongest tests of models require individual masses, particularly for calibrating the mass-luminosity relation. This is poorly constrained over the range of spectral types most influenced by clouds (mid-L to early-T). Given the observed prevalence of clouds in the atmospheres of directly imaged planets, testing models at such temperatures is crucial.We propose a 3-year program to obtain individual masses for a sample of 11 substellar binaries. Our proposal builds on nearly a decade of orbital monitoring from the ground to measure dynamical total masses. Our goal is thus to measure precise mass ratios, utilizing HST's unique wide-field, high-angular resolution astrometric capabilities. We will obtain WFC3-UVIS images capturing our targets and numerous reference stars so that we can measure the relative amount of orbital motion in each component to determine mass ratios. Three of our targets have I-band photocenter orbits measured at USNO and VLT and thus only require one epoch of resolved I-band imaging to unlock individual masses. We will use this first large sample of substellar individual masses to map out the mass-luminosity relation over a wide range of temperatures (1000-2000 K) including the L/T transition. This will become a touchstone sample for tests of ultracool atmospheric models in the era of JWST.

Mapping the Substellar Mass-Luminosity Relation Down to the L/T Transition

NASA Astrophysics Data System (ADS)

Dupuy, Trent

2017-08-01

Substellar models underpin our theoretical understanding of brown dwarfs and gas-giant exoplanets, so assessing their accuracy is paramount. The past several years have seen progress in testing models thanks to a growing number of dynamical (total) masses for brown dwarf binaries determined via (relative) orbit monitoring from ground-based AO. However, the strongest tests of models require individual masses, particularly for calibrating the mass-luminosity relation. This is poorly constrained over the range of spectral types most influenced by clouds (mid-L to early-T). Given the observed prevalence of clouds in the atmospheres of directly imaged planets, testing models at such temperatures is crucial.We propose a 3-year program to obtain individual masses for a sample of 11 substellar binaries. Our proposal builds on nearly a decade of orbital monitoring from the ground to measure dynamical total masses. Our goal is thus to measure precise mass ratios, utilizing HST's unique wide-field, high-angular resolution astrometric capabilities. We will obtain WFC3-UVIS images capturing our targets and numerous reference stars so that we can measure the relative amount of orbital motion in each component to determine mass ratios. Three of our targets have I-band photocenter orbits measured at USNO and VLT and thus only require one epoch of resolved I-band imaging to unlock individual masses. We will use this first large sample of substellar individual masses to map out the mass-luminosity relation over a wide range of temperatures (1000-2000 K) including the L/T transition. This will become a touchstone sample for tests of ultracool atmospheric models in the era of JWST.

Probing Ultracool Atmospheres and Substellar Interiors with Dynamical Masses

NASA Astrophysics Data System (ADS)

Dupuy, Trent

2010-09-01

After years of patient orbital monitoring, there is now a large sample of very low-mass stars and brown dwarfs with precise { 5%} dynamical masses. These binaries represent the gold standard for testing substellar theoretical models. Work to date has identified problems with the model-predicted broad-band colors, effective temperatures, and possibly even luminosity evolution with age. However, our ability to test models is currently limited by how well the individual components of these highly prized binaries are characterized. To solve this problem, we propose to use NICMOS and STIS to characterize this first large sample of ultracool binaries with well-determined dynamical masses. We will use NICMOS multi-band photometry to measure the SEDs of the binary components and thereby precisely estimate their spectral types and effective temperatures. We will use STIS to obtain resolved spectroscopy of the Li I doublet at 6708 A for a subset of three binaries whose masses lie very near the theoretical mass limit for lithium burning. The STIS data will provide the first ever resolved lithium measurements for brown dwarfs of known mass, enabling a direct probe of substellar interiors. Our proposed HST observations to characterize the components of these binaries is much less daunting in comparison to the years of orbital monitoring needed to yield dynamical masses, but these HST data are equally vital for robust tests of theory.

The sub-stellar birth rate from UKIDSS

NASA Astrophysics Data System (ADS)

Day-Jones, A. C.; Marocco, F.; Pinfield, D. J.; Zhang, Z. H.; Burningham, B.; Deacon, N.; Ruiz, M. T.; Gallardo, J.; Jones, H. R. A.; Lucas, P. W. L.; Jenkins, J. S.; Gomes, J.; Folkes, S. L.; Clarke, J. R. A.

2013-04-01

We present a new sample of mid-L to mid-T dwarfs with effective temperatures of 1100-1700 K selected from the UKIDSS Large Area Survey (LAS) and confirmed with infrared spectra from X-shooter/Very Large Telescope. This effective temperature range is especially sensitive to the formation history of Galactic brown dwarfs and allows us to constrain the form of the sub-stellar birth rate, with sensitivity to differentiate between a flat (stellar like) birth rate and an exponentially declining form. We present the discovery of 63 new L and T dwarfs from the UKIDSS LAS DR7, including the identification of 12 likely unresolved binaries, which form the first complete sub-set from our programme, covering 495 square degrees of sky, complete to J = 18.1. We compare our results for this sub-sample with simulations of differing birth rates for objects of masses 0.10-0.03 M⊙ and ages 1-10 Gyr. We find that the more extreme birth rates (e.g. a halo type form) can likely be excluded as the true form of the birth rate. In addition, we find that although there is substantial scatter we find a preference for a mass function, with a power-law index α in the range -1 < α < 0 that is consistent (within the errors) with the studies of late T dwarfs.

A CANDIDATE PLANETARY-MASS OBJECT WITH A PHOTOEVAPORATING DISK IN ORION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Min; Kim, Jinyoung Serena; Apai, Dániel

2016-12-20

In this work, we report the discovery of a candidate planetary-mass object with a photoevaporating protoplanetary disk, Proplyd 133-353, which is near the massive star θ {sup 1} Ori C at the center of the Orion Nebula Cluster (ONC). The object was known to have extended emission pointing away from θ {sup 1} Ori C, indicating ongoing external photoevaporation. Our near-infrared spectroscopic data and the location on the H–R diagram suggest that the central source of Proplyd 133-353 is substellar (∼M9.5) and has a mass probably less than 13 Jupiter mass and an age younger than 0.5 Myr. Proplyd 133-353more » shows a similar ratio of X-ray luminosity to stellar luminosity to other young stars in the ONC with a similar stellar luminosity and has a similar proper motion to the mean one of confirmed ONC members. We propose that Proplyd 133-353 formed in a very low-mass dusty cloud or an evaporating gas globule near θ {sup 1} Ori C as a second generation of star formation, which can explain both its young age and the presence of its disk.« less

The occurrence of planets and other substellar bodies around white dwarfs using K2

NASA Astrophysics Data System (ADS)

van Sluijs, L.; Van Eylen, V.

2018-03-01

The majority of stars both host planetary systems and evolve into a white dwarf (WD). To understand their post-main-sequence planetary system evolution, we present a search for transiting/eclipsing planets and other substellar bodies (SBs) around WDs using a sample of 1148 WDs observed by K2. Using transit injections, we estimate the completeness of our search. We place constraints on the occurrence of planets and SBs around WDs as a function of planet radius and orbital period. For short-period (P < 40 d) small objects, from asteroid-sized to 1.5 R⊕, these are the strongest constraints known to date. We further constrain the occurrence of hot Jupiters ( < 1.5 per cent), habitable zone Earth-sized planets ( < 28 per cent), and disintegrating short-period planets ( ˜ 12 per cent). We blindly recovered all previously known eclipsing objects, providing confidence in our analysis, and make all light curves publicly available.

Observational diagnostics of accretion on young stars and brown dwarfs

NASA Astrophysics Data System (ADS)

Stelzer, Beate; Argiroffi, Costanza

I present a summary of recent observational constraints on the accretion properties of young stars and brown dwarfs with focus on the high-energy emission. In their T Tauri phase young stars assemble a few percent of their mass by accretion from a disk. Various observational signatures of disks around pre-main sequence stars and the ensuing accretion process are found in the IR and optical regime: e.g. excess emission above the stellar photosphere, strong and broad emission lines, optical veiling. At high energies evidence for accretion is less obvious, and the X-ray emission from stars has historically been ascribed to magnetically confined coronal plasmas. While being true for the bulk of the emission, new insight obtained from XMM-Newton and Chandra observations has unveiled contributions from accretion and outflow processes to the X-ray emission from young stars. Their smaller siblings, the brown dwarfs, have been shown to undergo a T Tauri phase on the basis of optical/IR observations of disks and measurements of accretion rates. Most re-cently, first evidence was found for X-rays produced by accretion in a young brown dwarf, complementing the suspected analogy between stars and substellar objects.

Young Stellar Objects observed by MOST

NASA Astrophysics Data System (ADS)

Siwak, Michal

2013-07-01

In the recent years the MOST satellite gathered dozens of high quality light curves of Young Stellar Objects (YSO). We present the most interesting results obtained from the data collected between 2009-2013.

Deficit of Wide Binaries in the η Chamaeleontis Young Cluster

NASA Astrophysics Data System (ADS)

Brandeker, Alexis; Jayawardhana, Ray; Khavari, Parandis; Haisch, Karl E., Jr.; Mardones, Diego

2006-12-01

We have carried out a sensitive high-resolution imaging survey of stars in the young (6-8 Myr), nearby (97 pc) compact cluster around η Chamaeleontis to search for stellar and substellar companions. Our data were obtained using the NACO adaptive optics system on the ESO Very Large Telescope (VLT). Given its youth and proximity, any substellar companions are expected to be luminous, especially in the near-infrared, and thus easier to detect next to their parent stars. Here, we present VLT NACO adaptive optics imaging with companion detection limits for 17 η Cha cluster members, and follow-up VLT ISAAC near-infrared spectroscopy for companion candidates. The widest binary detected is ~0.2", corresponding to the projected separation 20 AU, despite our survey being sensitive down to substellar companions outside 0.3", and planetary-mass objects outside 0.5". This implies that the stellar companion probability outside 0.3" and the brown dwarf companion probability outside 0.5" are less than 0.16 with 95% confidence. We compare the wide binary frequency of η Cha to that of the similarly aged TW Hydrae association and estimate the statistical likelihood that the wide binary probability is equal in both groups to be less than 2×10-4. Even though the η Cha cluster is relatively dense, stellar encounters in its present configuration cannot account for the relative deficit of wide binaries. We thus conclude that the difference in wide binary probability in these two groups provides strong evidence for multiplicity properties being dependent on environment. In two appendices we derive the projected separation probability distribution for binaries, used to constrain physical separations from observed projected separations, and summarize statistical tools useful for multiplicity studies.

Young Stellar Objects from Soft to Hard X-rays

NASA Astrophysics Data System (ADS)

Güdel, Manuel

2009-05-01

Magnetically active stars are the sites of efficient particle acceleration and plasma heating, processes that have been studied in detail in the solar corona. Investigation of such processes in young stellar objects is much more challenging due to various absorption processes. There is, however, evidence for violent magnetic energy release in very young stellar objects. The impact on young stellar environments (e.g., circumstellar disk heating and ionization, operation of chemical networks, photoevaporation) may be substantial. Hard X-ray devices like those carried on Simbol-X will establish a basis for detailed studies of these processes.

Substellar fragmentation in self-gravitating fluids with a major phase transition

NASA Astrophysics Data System (ADS)

Füglistaler, A.; Pfenniger, D.

2015-06-01

Context. The observation of various ices in cold molecular clouds, the existence of ubiquitous substellar, cold H2 globules in planetary nebulae and supernova remnants, or the mere existence of comets suggest that the physics of very cold interstellar gas might be much richer than usually envisioned. At the extreme of low temperatures (≲10 K), H2 itself is subject to a phase transition crossing the entire cosmic gas density scale. Aims: This well-known, laboratory-based fact motivates us to study the ideal case of a cold neutral gaseous medium in interstellar conditions for which the bulk of the mass, instead of trace elements, is subject to a gas-liquid or gas-solid phase transition. Methods: On the one hand, the equilibrium of general non-ideal fluids is studied using the virial theorem and linear stability analysis. On the other hand, the non-linear dynamics is studied using computer simulations to characterize the expected formation of solid bodies analogous to comets. The simulations are run with a state-of-the-art molecular dynamics code (LAMMPS) using the Lennard-Jones inter-molecular potential. The long-range gravitational forces can be taken into account together with short-range molecular forces with finite limited computational resources, using super-molecules, provided the right scaling is followed. Results: The concept of super-molecule, where the phase transition conditions are preserved by the proper choice of the particle parameters, is tested with computer simulations, allowing us to correctly satisfy the Jeans instability criterion for one-phase fluids. The simulations show that fluids presenting a phase transition are gravitationally unstable as well, independent of the strength of the gravitational potential, producing two distinct kinds of substellar bodies, those dominated by gravity (planetoids) and those dominated by molecular attractive force (comets). Conclusions: Observations, formal analysis, and computer simulations suggest the

On Lithium-rich Red Giants. I. Engulfment of Substellar Companions

NASA Astrophysics Data System (ADS)

Aguilera-Gómez, Claudia; Chanamé, Julio; Pinsonneault, Marc H.; Carlberg, Joleen K.

2016-10-01

A small fraction of red giants are known to be lithium (Li) rich, in contradiction with expectations from stellar evolutionary theory. A possible explanation for these atypical giants is the engulfment of an Li-rich planet or brown dwarf by the star. In this work, we model the evolution of Li abundance in canonical red giants including the accretion of a substellar mass companion. We consider a wide range of stellar and companion masses, Li abundances, stellar metallicities, and planetary orbital periods. Based on our calculations, companions with masses lower than 15 {M}J dissolve in the convective envelope and can induce Li enrichment in regimes where extra mixing does not operate. Our models indicate that the accretion of a substellar companion can explain abundances up to A(Li) ≈ 2.2, setting an upper limit for Li-rich giants formed by this mechanism. Giants with higher abundances need another mechanism to be explained. For reasonable planetary distributions, we predict the Li abundance distribution of low-mass giants undergoing planet engulfment, finding that between 1% and 3% of them should have {{A}}({Li})≥slant 1.5. We show that depending on the stellar mass range, this traditional definition of Li-rich giants is misleading, as isolated massive stars would be considered anomalous while giants engulfing a companion would be set aside, flagged as normal. We explore the detectability of companion engulfment, finding that planets with masses higher than ∼ 7 {M}J produce a distinct signature, and that descendants of stars originating in the Li dip and low-luminosity red giants are ideal tests of this channel.

Optical Monitoring of Young Stellar Objects

NASA Astrophysics Data System (ADS)

Kar, Aman; Jang-Condell, Hannah; Kasper, David; Findlay, Joseph; Kobulnicky, Henry A.

2018-06-01

Observing Young Stellar Objects (YSOs) for variability in different wavelengths enables us to understand the evolution and structure of the protoplanetary disks around stars. The stars observed in this project are known YSOs that show variability in the Infrared. Targets were selected from the Spitzer Space Telescope Young Stellar Object Variability (YSOVAR) Program, which monitored star-forming regions in the mid-infrared. The goal of our project is to investigate any correlation between the variability in the infrared versus the optical. Infrared variability of YSOs is associated with the heating of the protoplanetary disk while accretion signatures are observed in the H-alpha region. We used the University of Wyoming’s Red Buttes Observatory to monitor these stars for signs of accretion using an H-alpha narrowband filter and the Johnson-Cousins filter set, over the Summer of 2017. We perform relative photometry and inspect for an image-to-image variation by observing these targets for a period of four months every two to three nights. The study helps us better understand the link between accretion and H-alpha activity and establish a disk-star connection.

Brown Dwarfs and Giant Planets Around Young Stars

NASA Astrophysics Data System (ADS)

Mahmud, Naved; Crockett, C.; Johns-Krull, C.; Prato, L.; Hartigan, P.; Jaffe, D.; Beichman, C.

2011-01-01

How dry is the brown dwarf (BD) desert at young ages? Previous radial velocity (RV) surveys have revealed that the frequency of BDs as close companions to solar-age stars in the field is extraordinarily low compared to the frequency of close planetary and stellar companions. Is this a formation or an evolutionary effect? Do close-in BDs form at lower rates, or are they destroyed by migration via interactions with a massive circumstellar disk, followed by assimilation into the parent star? To answer these questions, we are conducting an RV survey of 130 T Tauri stars in Taurus-Auriga (a few Myr old) and a dozen stars in the Pleiades (100 Myr old) to search for stellar reflex motions resulting from close substellar companions. Our goal is to measure the frequency of BDs at young ages. Detecting a higher frequency of BDs in young systems relative to the field will provide evidence for the migration theory as well as set limits on the migration timescale. Two additional goals are (1) to investigate the effect of star spots in young stars on RV observations, and (2) to detect the youngest-known giant exoplanet. We present results from the first few years of this survey. Strikingly, after completing observations of a third of our sample, we have yet to detect a single BD. Thus we can set limits on the dryness of the BD desert at young ages and shed light on the mysterious early lives of these objects.

X-shooter spectroscopy of young stellar objects in Lupus. Accretion properties of class II and transitional objects

NASA Astrophysics Data System (ADS)

Alcalá, J. M.; Manara, C. F.; Natta, A.; Frasca, A.; Testi, L.; Nisini, B.; Stelzer, B.; Williams, J. P.; Antoniucci, S.; Biazzo, K.; Covino, E.; Esposito, M.; Getman, F.; Rigliaco, E.

2017-04-01

The mass accretion rate, Ṁacc, is a key quantity for the understanding of the physical processes governing the evolution of accretion discs around young low-mass (M⋆ ≲ 2.0 M⊙) stars and substellar objects (YSOs). We present here the results of a study of the stellar and accretion properties of the (almost) complete sample of class II and transitional YSOs in the Lupus I, II, III and IV clouds, based on spectroscopic data acquired with the VLT/X-shooter spectrograph. Our study combines the dataset from our previous work with new observations of 55 additional objects. We have investigated 92 YSO candidates in total, 11 of which have been definitely identified with giant stars unrelated to Lupus. The stellar and accretion properties of the 81 bona fide YSOs, which represent more than 90% of the whole class II and transition disc YSO population in the aforementioned Lupus clouds, have been homogeneously and self-consistently derived, allowing for an unbiased study of accretion and its relationship with stellar parameters. The accretion luminosity, Lacc, increases with the stellar luminosity, L⋆, with an overall slope of 1.6, similar but with a smaller scatter than in previous studies. There is a significant lack of strong accretors below L⋆ ≈ 0.1 L⊙, where Lacc is always lower than 0.01 L⋆. We argue that the Lacc - L⋆ slope is not due to observational biases, but is a true property of the Lupus YSOs. The log Ṁacc - log M⋆ correlation shows a statistically significant evidence of a break, with a steeper relation for M⋆ ≲ 0.2 M⊙ and a flatter slope for higher masses. The bimodality of the Ṁacc - M⋆ relation is confirmed with four different evolutionary models used to derive the stellar mass. The bimodal behaviour of the observed relationship supports the importance of modelling self-gravity in the early evolution of the more massive discs, but other processes, such as photo-evaporation and planet formation during the YSO's lifetime, may

Social object play among young Japanese macaques (Macaca fuscata) in Arashiyama, Japan.

PubMed

Shimada, Masaki

2006-10-01

Social object play (SOP), i.e., social play using portable object(s), among young Japanese macaques (Macaca fuscata; 0-4 years old) in the Arashiyama E troop was studied using a modified sequence sampling method from July to October 2000. SOP was a relatively common activity for most of the young macaques and often continued for long periods. Participants used many kinds of object, including edible natural objects and artificial objects, such as plastic bottles, but they never used provisioned food or wild fruit in SOP bouts. An analysis of long bouts (>/=0.5 min) revealed the following interactive SOP features: (1) at any given time, participants used only one object, and only one participant held the object; (2) during SOP play-chasing, the object holder was likely to be chased by others; (3) during long bouts, the object changed hands frequently; and (4) agonistic competition for an object among young macaques was rare. Combinations of sexes, ages, relative ranks, or matrilines of the object holder and non-holder did not affect the tendency that the holder was chased by non-holder(s) during play-chasing. Even when there was a change in object holders, the repetitiveness of this interactive pattern, i.e., that the holder would be chased during SOP bouts, distinguished the SOP structure from that of other types of social play without object(s). General proximate social play mechanisms, such as self-handicapping or role taking, were associated with SOP. Other mechanisms that affected SOP included the following: (1) young macaques treated an object as a target in play competition, and (2) 'being the holder of a target object' was associated with the 'role of the chasee.'

A proposed search on the solar neighborhood for substellar objects

NASA Technical Reports Server (NTRS)

Reynolds, R. T.; Walker, R. G.; Tarter, J. C.

1980-01-01

The Infrared Astronomical Satellite (IRAS) program will produce an extremely sensitive all-sky survey over the wavelength region 8 to 120 microns when the mission is flown in 1982. These data will provide a novel opportunity to detect planetary-sized objects having masses smaller than 0.08 solar masses in or near the solar system. The improved detection limit of the IRAS will greatly increase the volume of space searched for such objects, as compared with previous optical and infrared studies.

A Catalogue of Massive Young Stellar Objects

NASA Astrophysics Data System (ADS)

Chan, S. J.; Henning, Th.; Schreyer, K.

1994-12-01

We report on an ongoing project to compile a catalogue of massive young stellar objects (YSOs). Massive young stellar objects are compact and luminous infrared sources. The stellar core is still surrounded by optically thick dust shells (cf. Henning 1990, Fundamentals of Cosmic Physics, 14, 321). This catalogue, which contains about 250 objects, will provide comprehensive information such as infrared and radio flux densities, association with maser sources, and outflow phenomena. The objects were selected from the IRAS Point Source Catalogue based on the following criteria: (1) IRAS flux density qualities >= 2 in the 4 IRAS bands (12 microns, 25 microns, 60 microns and 100 microns). (2) Fnu(12microns) <= Fnu(25microns) <= Fnu(60microns) <= F_ν(100microns) Fnu(100microns) >= 1000 Jy (3) IRAS colors (including uncertainty 0.15) should be within the following color box: -0.15 >= R(12/25) >= 1.15, -0.15 >= R(25/60) >= 0.75, -0.35 >= R(60/100) >= 0.35, where R(i/j)=jF_nu (i)/iF_nu (j) (Henning et al. 1990, A&A, 227, 542) (4) IRAS idtype (type of objects)!= 1; objects are not associated with galaxies or late-type stars; ∣b∣ <= 10{(deg}) Our main goal is to collect the observational data of these sources as complete as possible. The flux densities from near-infrared to radio range are assembled (J, H, K bands, IRAS bands, 350 microns, 800 microns and 1.3 mm bands, 2 cm and 6 cm bands). The information on dust features (such as ice, silicate, PAH) comes from the IRAS Low Resolution Spectrometer Atlas and literature (cf. Volk & Cohen, 1989, AJ, 98, 931). The maser sources (H_2O, type I OH, CH_3OH) and NH_3, HCO(+) , and CS molecular line data towards these objects, which have been observed, are also reported. The CO outflow velocity will be given if the object is found to be associated with an outflow.

Self-initiated object-location memory in young and older adults.

PubMed

Berger-Mandelbaum, Anat; Magen, Hagit

2017-11-20

The present study explored self-initiated object-location memory in ecological contexts, as aspect of memory that is largely absent from the research literature. Young and older adults memorized objects-location associations they selected themselves or object-location associations provided to them, and elaborated on the strategy they used when selecting the locations themselves. Retrieval took place 30 min and 1 month after encoding. The results showed an age-related decline in self-initiated and provided object-location memory. Older adults benefited from self-initiation more than young adults when tested after 30 min, while the benefit was equal when tested after 1 month. Furthermore, elaboration enhanced memory only in older adults, and only after 30 min. Both age groups used deep encoding strategies on the majority of the trials, but their percentage was lower in older adults. Overall, the study demonstrated the processes involved in self-initiated object-location memory, which is an essential part of everyday functioning.

Radio emission in ultracool dwarfs: The nearby substellar triple system VHS 1256-1257

NASA Astrophysics Data System (ADS)

Guirado, J. C.; Azulay, R.; Gauza, B.; Pérez-Torres, M. A.; Rebolo, R.; Climent, J. B.; Zapatero Osorio, M. R.

2018-02-01

Aim. With the purpose of investigating the radio emission of new ultracool objects, we carried out a targeted search in the recently discovered system VHS J125601.92-125723.9 (hereafter VHS 1256-1257); this system is composed by an equal-mass M7.5 binary and a L7 low-mass substellar object located at only 15.8 pc. Methods: We observed in phase-reference mode the system VHS 1256-1257 with the Karl G. Jansky Very Large Array at X band and L band and with the European VLBI Network at L band in several epochs during 2015 and 2016. Results: We discovered radio emission at X band spatially coincident with the equal-mass M7.5 binary with a flux density of 60 μJy. We determined a spectral index α = ‑1.1 ± 0.3 between 8 and 12 GHz, suggesting that non-thermal, optically thin, synchrotron, or gyrosynchrotron radiation is responsible for the observed radio emission. Interestingly, no signal is seen at L band where we set a 3σ upper limit of 20 μJy. This might be explained by strong variability of the binary or self-absorption at this frequency. By adopting the latter scenario and gyrosynchrotron radiation, we constrain the turnover frequency to be in the interval 5-8.5 GHz, from which we infer the presence of kG-intense magnetic fields in the M7.5 binary. Our data impose a 3σ upper bound to the radio flux density of the L7 object of 9 μJy at 10 GHz.

Exploring the brown dwarf desert: new substellar companions from the SDSS-III MARVELS survey

NASA Astrophysics Data System (ADS)

Grieves, Nolan; Ge, Jian; Thomas, Neil; Ma, Bo; Sithajan, Sirinrat; Ghezzi, Luan; Kimock, Ben; Willis, Kevin; De Lee, Nathan; Lee, Brian; Fleming, Scott W.; Agol, Eric; Troup, Nicholas; Paegert, Martin; Schneider, Donald P.; Stassun, Keivan; Varosi, Frank; Zhao, Bo; Jian, Liu; Li, Rui; Porto de Mello, Gustavo F.; Bizyaev, Dmitry; Pan, Kaike; Dutra-Ferreira, Letícia; Lorenzo-Oliveira, Diego; Santiago, Basílio X.; da Costa, Luiz N.; Maia, Marcio A. G.; Ogando, Ricardo L. C.; del Peloso, E. F.

2017-06-01

Planet searches using the radial velocity technique show a paucity of companions to solar-type stars within ˜5 au in the mass range of ˜10-80 MJup. This deficit, known as the brown dwarf desert, currently has no conclusive explanation. New substellar companions in this region help assess the reality of the desert and provide insight to the formation and evolution of these objects. Here, we present 10 new brown dwarf and 2 low-mass stellar companion candidates around solar-type stars from the Multi-object APO Radial Velocity Exoplanet Large-Area Survey (MARVELS) of the Sloan Digital Sky Survey III. These companions were selected from processed MARVELS data using the latest University of Florida Two Dimensional pipeline, which shows significant improvement and reduction of systematic errors over previous pipelines. The 10 brown dwarf companions range in mass from ˜13 to 76 MJup and have orbital radii of less than 1 au. The two stellar companions have minimum masses of ˜98 and 100 MJup. The host stars of the MARVELS brown dwarf sample have a mean metallicity of [Fe/H] = 0.03 ± 0.08 dex. Given our stellar sample we estimate the brown dwarf occurrence rate around solar-type stars with periods less than ˜300 d to be ˜0.56 per cent.

The First Brown Dwarf/Planetary-mass Object in the 32 Orionis Group

NASA Astrophysics Data System (ADS)

Burgasser, Adam J.; Lopez, Mike A.; Mamajek, Eric E.; Gagné, Jonathan; Faherty, Jacqueline K.; Tallis, Melisa; Choban, Caleb; Tamiya, Tomoki; Escala, Ivanna; Aganze, Christian

2016-03-01

The 32 Orionis group is a co-moving group of roughly 20 young (24 Myr) M3-B5 stars 100 pc from the Sun. Here we report the discovery of its first substellar member, WISE J052857.69+090104.2. This source was previously reported to be an M giant star based on its unusual near-infrared spectrum and lack of measureable proper motion. We re-analyze previous data and new moderate-resolution spectroscopy from Magellan/Folded-port InfraRed Echellette to demonstrate that this source is a young near-infrared L1 brown dwarf with very low surface gravity features. Spectral model fits indicate Teff = 1880{}-70+150 K and {log}g = 3.8{}-0.2+0.2, consistent with a 15-22 Myr object with a mass near the deuterium-burning limit. Its sky position, estimated distance, kinematics (both proper motion and radial velocity), and spectral characteristics are all consistent with membership in 32 Orionis, and its temperature and age imply a mass (M = {14}-3+4 MJ) that straddles the brown dwarf/planetary-mass object boundary. The source has a somewhat red J-W2 color compared to other L1 dwarfs, but this is likely a low-gravity-related temperature offset; we find no evidence of significant excess reddening from a disk or cool companion in the 3-5 μm waveband. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

The Widest-separation Substellar Companion Candidate to a Binary T Tauri Star

NASA Astrophysics Data System (ADS)

Kuzuhara, M.; Tamura, M.; Ishii, M.; Kudo, T.; Nishiyama, S.; Kandori, R.

2011-04-01

The results of near-infrared imaging and spectroscopy of a substellar companion (SR12 C), with a possible planetary mass, of a binary T Tauri star (SR12 AB) in the ρ Ophiuchi star-forming region are presented. The object is separated by ~8farcs7, corresponding to ~1100 AU at 125 pc, and has an H-band brightness of 15.2 mag and infrared spectra suggesting a spectral type of M9.0 ± 0.5. It is confirmed that SR12 C is physically related to the ρ Ophiuchi star-forming region from its common proper motion with SR12 AB and its youth is confirmed by a gravity-sensitive spectral feature. Furthermore, based on the number of known members of the ρ Ophiuchi star-forming region in the area in which SR12 AB exists, the probability of a chance alignment is ~1% and it is therefore likely that SR12 C is physically associated with SR12 AB. The mass of SR12 C is estimated by comparing its estimated luminosity and assumed age with the theoretical age-luminosity relation. SR12 C is identified as an extremely low-mass (0.013 ± 0.007 M sun) object, but its separation from its parent star is the widest among planetary-mass companion (PMC) candidates imaged to date. In addition, SR12 C is the first PMC candidate directly imaged around a binary star. This discovery suggests that PMCs form via multiple star formation processes including disk gravitational instability and cloud core fragmentation.

A Search for Pulsation in Young Brown Dwarfs and Very Low Mass Stars

NASA Astrophysics Data System (ADS)

Cody, Ann Marie

2012-05-01

In 2005, Palla and Baraffe proposed that brown dwarfs and very low mass stars (<0.1 solar masses) may be unstable to radial oscillations during the pre-main-sequence deuterium burning phase. With associated oscillation periods of 1--4 hours, this potentially new class of pulsation offers unprecedented opportunities to probe the interiors and evolution of low-mass objects in the 1--15 million year age range. Furthermore, several previous reports of short-period variability have suggested that deuterium-burning pulsation is in fact at work in young clusters. For my dissertation, I developed a photometric monitoring campaign to search for low-amplitude periodic variability in young brown dwarfs and very low mass stars using meter-class telescopes from both the ground and space. The resulting high-precision, high-cadence time-series photometry targeted four young clusters and achieved sensitivity to periodic oscillations with photometric amplitudes down to several millimagnitudes. This unprecedented variability census probed timescales ranging from minutes to weeks in a sample of 200 young, low-mass cluster members of IC 348, Sigma Orionis, Chamaeleon I, and Upper Scorpius. While I find a dearth of photometric periods under 10 hours, the campaign's high time resolution and precision have enabled detailed study of diverse light curve behavior in the clusters: rotational spot modulation, accretion signatures, and occultations by surrounding disk material. Analysis of the data has led to the establishment of a lower limit for the timescale of periodic photometric variability in young low-mass and substellar objects, an extension of the rotation period distribution to the brown dwarf regime, as well as insights into the connection between variability and circumstellar disks in the Sigma Orionis and Chamaeleon I clusters.

An ALMA and MagAO Study of the Substellar Companion GQ Lup B*

NASA Astrophysics Data System (ADS)

Wu, Ya-Lin; Sheehan, Patrick D.; Males, Jared R.; Close, Laird M.; Morzinski, Katie M.; Teske, Johanna K.; Haug-Baltzell, Asher; Merchant, Nirav; Lyons, Eric

2017-02-01

Multi-wavelength observations provide a complementary view of the formation of young, directly imaged planet-mass companions. We report the ALMA 1.3 mm and Magellan adaptive optics Hα, I\\prime , z\\prime , and Y S observations of the GQ Lup system, a classical T Tauri star with a 10{--}40 {M}{Jup} substellar companion at ˜110 au projected separation. We estimate the accretion rates for both components from the observed Hα fluxes. In our ˜0.″05 resolution ALMA map, we resolve GQ Lup A’s disk in the dust continuum, but no signal is found from the companion. The disk is compact, with a radius of ˜22 au, a dust mass of ˜6 M ⊕, an inclination angle of ˜56°, and a very flat surface density profile indicative of a radial variation in dust grain sizes. No gaps or inner cavity are found in the disk, so there is unlikely a massive inner companion to scatter GQ Lup B outward. Thus, GQ Lup B might have formed in situ via disk fragmentation or prestellar core collapse. We also show that GQ Lup A’s disk is misaligned with its spin axis, and possibly with GQ Lup B’s orbit. Our analysis on the tidal truncation radius of GQ Lup A’s disk suggests that GQ Lup B’s orbit might have a low eccentricity. This paper includes data gathered with the 6.5 m Magellan Clay Telescope at Las Campanas Observatory, Chile.

THE EXTREMELY RED, YOUNG L DWARF PSO J318.5338–22.8603: A FREE-FLOATING PLANETARY-MASS ANALOG TO DIRECTLY IMAGED YOUNG GAS-GIANT PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Michael C.; Magnier, Eugene A.; Kotson, Michael C.

2013-11-10

We have discovered using Pan-STARRS1 an extremely red late-L dwarf, which has (J – K){sub MKO} = 2.78 and (J – K){sub 2MASS} = 2.84, making it the reddest known field dwarf and second only to 2MASS J1207–39b among substellar companions. Near-IR spectroscopy shows a spectral type of L7 ± 1 and reveals a triangular H-band continuum and weak alkali (K I and Na I) lines, hallmarks of low surface gravity. Near-IR astrometry from the Hawaii Infrared Parallax Program gives a distance of 24.6 ± 1.4 pc and indicates a much fainter J-band absolute magnitude than field L dwarfs. Themore » position and kinematics of PSO J318.5–22 point to membership in the β Pic moving group. Evolutionary models give a temperature of 1160{sup +30}{sub -40} K and a mass of 6.5{sup +1.3}{sub -1.0} M {sub Jup}, making PSO J318.5–22 one of the lowest mass free-floating objects in the solar neighborhood. This object adds to the growing list of low-gravity field L dwarfs and is the first to be strongly deficient in methane relative to its estimated temperature. Comparing their spectra suggests that young L dwarfs with similar ages and temperatures can have different spectral signatures of youth. For the two objects with well constrained ages (PSO J318.5–22 and 2MASS J0355+11), we find their temperatures are ≈400 K cooler than field objects of similar spectral type but their luminosities are similar, i.e., these young L dwarfs are very red and unusually cool but not 'underluminous'. Altogether, PSO J318.5–22 is the first free-floating object with the colors, magnitudes, spectrum, luminosity, and mass that overlap the young dusty planets around HR 8799 and 2MASS J1207–39.« less

Priming of familiar and unfamiliar visual objects over delays in young and older adults.

PubMed

Soldan, Anja; Hilton, H John; Cooper, Lynn A; Stern, Yaakov

2009-03-01

Although priming of familiar stimuli is usually age invariant, little is known about how aging affects priming of preexperimentally unfamiliar stimuli. Therefore, this study investigated the effects of aging and encoding-to-test delays (0 min, 20 min, 90 min, and 1 week) on priming of unfamiliar objects in block-based priming paradigms. During the encoding phase, participants viewed pictures of novel objects (Experiments 1 and 2) or novel and familiar objects (Experiment 3) and judged their left-right orientation. In the test block, priming was measured using the possible-impossible object-decision test (Experiment 1), symmetric-asymmetric object-decision test (Experiment 2), and real-nonreal object-decision test (Experiment 3). In Experiments 1 and 2, young adults showed priming for unfamiliar objects at all delays, whereas older adults whose baseline task performance was similar to that of young adults did not show any priming. Experiment 3 found no effects of age or delay on priming of familiar objects; however, priming of unfamiliar objects was only observed in the young participants. This suggests that when older adults cannot rely on preexisting memory representations, age-related deficits in priming can emerge.

Young Children's Preference for Unique Owned Objects

PubMed Central

Gelman, Susan A.; Davidson, Natalie S.

2016-01-01

An important aspect of human thought is the value we place on unique individuals. Adults place higher value on authentic works of art than exact replicas, and young children at times value their original possessions over exact duplicates. What is the scope of this preference in early childhood, and when do children understand its subjective nature? On a series of trials, we asked three-year-olds (N=36) to choose between two toys for either themselves or the researcher: an old (visibly used) toy versus a new (more attractive) toy matched in type and appearance (e.g., old vs. brand-new blanket). Focal pairs contrasted the child's own toy with a matched new object; Control pairs contrasted toys the child had never seen before. Children preferred the old toys for Focal pairs only, and treated their own preferences as not shared by the researcher. By 3 years of age, young children place special value on unique individuals, and understand the subjective nature of that value. PMID:27395441

Multi-wavelength Observations of Accreting Compact Objects

NASA Astrophysics Data System (ADS)

Hernandez Santisteban, Juan Venancio

2016-11-01

The study of compact binaries invokes core astrophysical concepts ranging from stellar and sub-stellar atmospheres and interiors, stellar and binary evolution to physics of accretion. All of these systems are hosts to a compact object a white dwarf, neutron star or black hole ???? which produces a wide variety of exotic and energetic phenomena across the full electromagnetic spectrum. In this thesis, I will make use of multi-wavelength observations ranging from far-ultraviolet to nearinfrared in order to investigate two main topics: a) the late evolution of cataclysmic variables, and b) the accreting state of transitional millisecond pulsars. Firstly, I analyse the Very Large Telescope X-Shooter time-resolved spectroscopy of the short orbital period cataclysmic variable, SDSS J1433+1011, in Chapter 2. The wide wavelength coverage allowed me to perform a detailed characterisation of the system, as well as a direct mass measurement of the brown dwarf companion. I show that the donor in SDSS J1433+1011 successfully transitioned from the stellar to sub-stellar regime, as predicted by evolutionary models. Further light-curve modelling allowed me to show that a low albedo as well as a low heat circulation efficiency is present in the atmosphere of the sub-stellar donor. In Chapter 3, I analyse data from large synoptic surveys, such as SDSS and PTF, to search for the predicted population of dead cataclysmic variables. Following the non-detection of dead CVs, I was able to estimate the space density (?0 < 2?10????5 pc????3) of this hidden population via a Monte Carlo simulation of the Galactic CV population. In Chapter 4, I present Hubble Space Telescope ultraviolet observations of the transitional millisecond pulsar PSR J1023+0038, during its latest accretion state. In combination with optical and near-infrared data, I show that a standard accretion disc does not reach the magnetosphere of the neutron star. Instead, the overall spectrum is consistent with a truncated disc

Spatially Resolved Spectroscopy of the PMS Quadruple GG Tau: Evidence for a Substellar Companion

NASA Astrophysics Data System (ADS)

White, R. J.; Ghez, A. M.; Schultz, G.; Reid, I. N.

1998-05-01

We present spatially resolved optical spectra from HST (FOS) and the Keck Telescope (HIRES & LRIS) of the components of the quadruple PMS system GG Tau. According to the latest PMS evolutionary models, the coldest component of this system, GG Tau/c B, appears to be substellar with a preliminary mass of only 50 M_J. This putative brown dwarf is especially intriguing as it shows clear signatures of accretion. The components of this quadruple, which span a wide range in mass, are used to test theoretical low mass PMS evolutionary models under the assumption that the components should be coeval.

Young children's preference for unique owned objects.

PubMed

Gelman, Susan A; Davidson, Natalie S

2016-10-01

An important aspect of human thought is the value we place on unique individuals. Adults place higher value on authentic works of art than exact replicas, and young children at times value their original possessions over exact duplicates. What is the scope of this preference in early childhood, and when do children understand its subjective nature? On a series of trials, we asked three-year-olds (N=36) to choose between two toys for either themselves or the researcher: an old (visibly used) toy vs. a new (more attractive) toy matched in type and appearance (e.g., old vs. brand-new blanket). Focal pairs contrasted the child's own toy with a matched new object; Control pairs contrasted toys the child had never seen before. Children preferred the old toys for Focal pairs only, and treated their own preferences as not shared by the researcher. By 3years of age, young children place special value on unique individuals, and understand the subjective nature of that value. Copyright © 2016 Elsevier B.V. All rights reserved.

Confirmation and characterization of young planetary companions hidden in the HST NICMOS archive

NASA Astrophysics Data System (ADS)

Pueyo, Laurent

2013-10-01

We propose to conduct WFC3 high contrast observations of six faint planetary candidates orbiting young {1 to 100 Myrs} stars identified in archival HST NICMOS coronagraphic data as part of our team's program AR-12652. Such rare objects are of the utmost importance to comparative exo-planetology as their physical properties reflect the initial conditions of still poorly constrained planetary formation mechanisms. Moreover directly imaged systems are precious artifacts in the expanding exo-planetary treasure trove as they are readily available for spectroscopic characterization. Our statistical analysis, which combines population synthesis models and empirical inspections of the entire NICMOS field of view for all sources observed in coronaraphic mode, almost guarantees that one of these six faint candidates is associated with its putative host star. We will conduct our observation in four near infrared filter, F125W, F160W to establish the baseline luminosity of our candidates and in F127M and F139M in order to probe the depth their water absorption features, characteristic of substellar /exo-planetary like atmospheres. Because of the youth of our targets, this program, which only requires a modest 12 HST orbits, will almost certainly identify and image a young or adolescent exo-planet.

Imaging Young Stellar Objects with VLTi/PIONIER

NASA Astrophysics Data System (ADS)

Kluska, J.; Malbet, F.; Berger, J.-P.; Benisty, M.; Lazareff, B.; Le Bouquin, J.-B.; Baron, F.; Dominik, C.; Isella, A.; Juhasz, A.; Kraus, S.; Lachaume, R.; Ménard, F.; Millan-Gabet, R.; Monnier, J.; Pinte, C.; Soulez, F.; Tallon, M.; Thi, W.-F.; Thiébaut, É.; Zins, G.

2014-04-01

Optical interferometry imaging is designed to help us to reveal complex astronomical sources without a prior model. Among these complex objects are the young stars and their environments, which have a typical morphology with a point-like source, surrounded by circumstellar material with unknown morphology. To image them, we have developed a numerical method that removes completely the stellar point source and reconstructs the rest of the image, using the differences in the spectral behavior between the star and its circumstellar material. We aim to reveal the first Astronomical Units of these objects where many physical phenomena could interplay: the dust sublimation causing a puffed-up inner rim, a dusty halo, a dusty wind or an inner gaseous component. To investigate more deeply these regions, we carried out the first Large Program survey of HAeBe stars with two main goals: statistics on the geometry of these objects at the first astronomical unit scale and imaging their very close environment. The images reveal the environment, which is not polluted by the star and allows us to derive the best fit for the flux ratio and the spectral slope. We present the first images from this survey and the application of the imaging method on other astronomical objects.

Social categories guide young children's preferences for novel objects

PubMed Central

Shutts, Kristin; Banaji, Mahzarin R.; Spelke, Elizabeth S.

2009-01-01

To whom do children look when deciding on their own preferences? To address this question, three-year-old children were asked to choose between objects or activities that were endorsed by unfamiliar people who differed in gender, race (White, Black), or age (child, adult). In Experiment 1, children demonstrated robust preferences for objects and activities endorsed by children of their own gender, but less consistent preferences for objects and activities endorsed by children of their own race. In Experiment 2, children selected objects and activities favored by people of their own gender and age. In neither study did most children acknowledge the influence of these social categories. These findings suggest that gender and age categories are encoded spontaneously and influence children's preferences and choices. For young children, gender and age may be more powerful guides to preferences than race. PMID:20590724

ClassLess: A Comprehensive Database of Young Stellar Objects

NASA Astrophysics Data System (ADS)

Hillenbrand, Lynne A.; baliber, nairn

2015-08-01

We have designed and constructed a database intended to house catalog and literature-published measurements of Young Stellar Objects (YSOs) within ~1 kpc of the Sun. ClassLess, so called because it includes YSOs in all stages of evolution, is a relational database in which user interaction is conducted via HTML web browsers, queries are performed in scientific language, and all data are linked to the sources of publication. Each star is associated with a cluster (or clusters), and both spatially resolved and unresolved measurements are stored, allowing proper use of data from multiple star systems. With this fully searchable tool, myriad ground- and space-based instruments and surveys across wavelength regimes can be exploited. In addition to primary measurements, the database self consistently calculates and serves higher level data products such as extinction, luminosity, and mass. As a result, searches for young stars with specific physical characteristics can be completed with just a few mouse clicks. We are in the database population phase now, and are eager to engage with interested experts worldwide on local galactic star formation and young stellar populations.

Mid infrared observations of Van Maanen 2: no substellar companion.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farihi, J; Becklin, E; Macintosh, B

2004-11-03

The results of a comprehensive infrared imaging search for the putative 0.06 M{sub {circle_dot}} astrometric companion to the 4.4 pc white dwarf van Mannen 2 are reported. Adaptive optics images acquired at 3.8 {micro}m reveal a diffraction limited core of 0.09 inch and no direct evidence of a secondary. Models predict that at 5 Gyr, a 50 M{sub J} brown dwarf would be only 1 magnitude fainter than van Maanen 2 at this wavelength and the astrometric analysis suggested a separation of 0.2 inch. In the case of a chance alignment along the line of sight, a 0.4 mag excessmore » should be measured. An independent photometric observation at the same wavelength reveals no excess. In addition, there exist published ISO observations of van Maanen 2 at 6.8 {micro}m and 15.0 {micro}m which are consistent with photospheric flux of a 6750 K white dwarf. If recent brown dwarf models are correct, there is no substellar companion with T{sub eff} {approx}> 500 K.« less

Employing Machine-Learning Methods to Study Young Stellar Objects

NASA Astrophysics Data System (ADS)

Moore, Nicholas

2018-01-01

Vast amounts of data exist in the astronomical data archives, and yet a large number of sources remain unclassified. We developed a multi-wavelength pipeline to classify infrared sources. The pipeline uses supervised machine learning methods to classify objects into the appropriate categories. The program is fed data that is already classified to train it, and is then applied to unknown catalogues. The primary use for such a pipeline is the rapid classification and cataloging of data that would take a much longer time to classify otherwise. While our primary goal is to study young stellar objects (YSOs), the applications extend beyond the scope of this project. We present preliminary results from our analysis and discuss future applications.

The Palomar Transient Factory Orion Project: Eclipsing Binaries and Young Stellar Objects

NASA Astrophysics Data System (ADS)

van Eyken, Julian C.; Ciardi, David R.; Rebull, Luisa M.; Stauffer, John R.; Akeson, Rachel L.; Beichman, Charles A.; Boden, Andrew F.; von Braun, Kaspar; Gelino, Dawn M.; Hoard, D. W.; Howell, Steve B.; Kane, Stephen R.; Plavchan, Peter; Ramírez, Solange V.; Bloom, Joshua S.; Cenko, S. Bradley; Kasliwal, Mansi M.; Kulkarni, Shrinivas R.; Law, Nicholas M.; Nugent, Peter E.; Ofek, Eran O.; Poznanski, Dovi; Quimby, Robert M.; Grillmair, Carl J.; Laher, Russ; Levitan, David; Mattingly, Sean; Surace, Jason A.

2011-08-01

The Palomar Transient Factory (PTF) Orion project is one of the experiments within the broader PTF survey, a systematic automated exploration of the sky for optical transients. Taking advantage of the wide (3fdg5 × 2fdg3) field of view available using the PTF camera installed at the Palomar 48 inch telescope, 40 nights were dedicated in 2009 December to 2010 January to perform continuous high-cadence differential photometry on a single field containing the young (7-10 Myr) 25 Ori association. Little is known empirically about the formation of planets at these young ages, and the primary motivation for the project is to search for planets around young stars in this region. The unique data set also provides for much ancillary science. In this first paper, we describe the survey and the data reduction pipeline, and present some initial results from an inspection of the most clearly varying stars relating to two of the ancillary science objectives: detection of eclipsing binaries and young stellar objects. We find 82 new eclipsing binary systems, 9 of which are good candidate 25 Ori or Orion OB1a association members. Of these, two are potential young W UMa type systems. We report on the possible low-mass (M-dwarf primary) eclipsing systems in the sample, which include six of the candidate young systems. Forty-five of the binary systems are close (mainly contact) systems, and one of these shows an orbital period among the shortest known for W UMa binaries, at 0.2156509 ± 0.0000071 days, with flat-bottomed primary eclipses, and a derived distance that appears consistent with membership in the general Orion association. One of the candidate young systems presents an unusual light curve, perhaps representing a semi-detached binary system with an inflated low-mass primary or a star with a warped disk, and may represent an additional young Orion member. Finally, we identify 14 probable new classical T-Tauri stars in our data, along with one previously known (CVSO 35) and

Variability of Massive Young Stellar Objects in Cygnus-X

NASA Astrophysics Data System (ADS)

Thomas, Nancy H.; Hora, J. L.; Smith, H. A.

2013-01-01

Young stellar objects (YSOs) are stars in the process of formation. Several recent investigations have shown a high rate of photometric variability in YSOs at near- and mid-infrared wavelengths. Theoretical models for the formation of massive stars (1-10 solar masses) remain highly idealized, and little is known about the mechanisms that produce the variability. An ongoing Spitzer Space Telescope program is studying massive star formation in the Cygnus-X region. In conjunction with the Spitzer observations, we have conducted a ground-based near-infrared observing program of the Cygnus-X DR21 field using PAIRITEL, the automated infrared telescope at Whipple Observatory. Using the Stetson index for variability, we identified variable objects and a number of variable YSOs in our time-series PAIRITEL data of DR21. We have searched for periodicity among our variable objects using the Lomb-Scargle algorithm, and identified periodic variable objects with an average period of 8.07 days. Characterization of these variable and periodic objects will help constrain models of star formation present. This work is supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 0754568 and by the Smithsonian Institution.

ClassLess: A Comprehensive Database of Young Stellar Objects

NASA Astrophysics Data System (ADS)

Hillenbrand, Lynne; Baliber, Nairn

2015-01-01

We have designed and constructed a database housing published measurements of Young Stellar Objects (YSOs) within ~1 kpc of the Sun. ClassLess, so called because it includes YSOs in all stages of evolution, is a relational database in which user interaction is conducted via HTML web browsers, queries are performed in scientific language, and all data are linked to the sources of publication. Each star is associated with a cluster (or clusters), and both spatially resolved and unresolved measurements are stored, allowing proper use of data from multiple star systems. With this fully searchable tool, myriad ground- and space-based instruments and surveys across wavelength regimes can be exploited. In addition to primary measurements, the database self consistently calculates and serves higher level data products such as extinction, luminosity, and mass. As a result, searches for young stars with specific physical characteristics can be completed with just a few mouse clicks.

Young People's Perceptions of the Objective Physical Activity Monitoring Process: A Qualitative Exploration

ERIC Educational Resources Information Center

Scott, Joseph J.; Hansen, Vibeke; Morgan, Philip J.; Plotnikoff, Ronald C.; Lubans, David R.

2018-01-01

Objective: To explore young people's perceptions of pedometers and investigate behaviours exhibited while being monitored. Design: Qualitative design using six focus groups with participants (mean age 14.7 years). Setting: Study participants (n = 24) were randomly selected from a previous study of 123 young people aged 14-15 years from three…

The peculiar dipping events in the disc-bearing young-stellar object EPIC 204278916

NASA Astrophysics Data System (ADS)

Scaringi, S.; Manara, C. F.; Barenfeld, S. A.; Groot, P. J.; Isella, A.; Kenworthy, M. A.; Knigge, C.; Maccarone, T. J.; Ricci, L.; Ansdell, M.

2016-12-01

EPIC 204278916 has been serendipitously discovered from its K2 light curve that displays irregular dimmings of up to 65 per cent for ≈25 consecutive days out of 78.8 d of observations. For the remaining duration of the observations, the variability is highly periodic and attributed to stellar rotation. The star is a young, low-mass (M-type) pre-main-sequence star with clear evidence of a resolved tilted disc from Atacama Large Millimeter/submillimeter Array (ALMA) observations. We examine the K2 light curve in detail and hypothesize that the irregular dimmings are caused by either a warped inner disc edge or transiting cometary-like objects in either circular or eccentric orbits. The explanations discussed here are particularly relevant for other recently discovered young objects with similar absorption dips.

YOUNG STELLAR CLUSTERS CONTAINING MASSIVE YOUNG STELLAR OBJECTS IN THE VVV SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borissova, J.; Alegría, S. Ramírez; Kurtev, R.

The purpose of this research is to study the connections of the global properties of eight young stellar clusters projected in the Vista Variables in the Via Lactea (VVV) ESO Large Public Survey disk area and their young stellar object (YSO) populations. The analysis is based on the combination of spectroscopic parallax-based reddening and distance determinations with main-sequence and pre-main-sequence ishochrone fitting to determine the basic parameters (reddening, age, distance) of the sample clusters. The lower mass limit estimations show that all clusters are low or intermediate mass (between 110 and 1800  M {sub ⊙}), the slope Γ of themore » obtained present-day mass functions of the clusters is close to the Kroupa initial mass function. The YSOs in the cluster’s surrounding fields are classified using low resolution spectra, spectral energy distribution fits with theoretical predictions, and variability, taking advantage of multi-epoch VVV observations. All spectroscopically confirmed YSOs (except one) are found to be massive (more than 8 M {sub ⊙}). Using VVV and GLIMPSE color–color cuts we have selected a large number of new YSO candidates, which are checked for variability and 57% are found to show at least low-amplitude variations. In few cases it was possible to distinguish between YSO and AGB classifications on the basis of light curves.« less

DORSAL HIPPOCAMPAL PROGESTERONE INFUSIONS ENHANCE OBJECT RECOGNITION IN YOUNG FEMALE MICE

PubMed Central

Orr, Patrick T.; Lewis, Michael C.; Frick, Karyn M.

2009-01-01

The effects of progesterone on memory are not nearly as well studied as the effects of estrogens. Although progesterone can reportedly enhance spatial and/or object recognition in female rodents when given immediately after training, previous studies have injected progesterone systemically, and therefore, the brain regions mediating this enhancement are not clear. As such, this study was designed to determine the role of the dorsal hippocampus in mediating the beneficial effect of progesterone on object recognition. Young ovariectomized C57BL/6 mice were trained in a hippocampal-dependent object recognition task utilizing two identical objects, and then immediately or 2 hrs afterwards, received bilateral dorsal hippocampal infusions of vehicle or 0.01, 0.1, or 1.0 μg/μl water-soluble progesterone. Forty-eight hours later, object recognition memory was tested using a previously explored object and a novel object. Relative to the vehicle group, memory for the familiar object was enhanced in all groups receiving immediate infusions of progesterone. Progesterone infusion delayed 2 hrs after training did not affect object recognition. These data suggest that the dorsal hippocampus may play a critical role in progesterone-induced enhancement of object recognition. PMID:19477194

The Low-mass Population in the Young Cluster Stock 8: Stellar Properties and Initial Mass Function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jose, Jessy; Herczeg, Gregory J.; Fang, Qiliang

The evolution of H ii regions/supershells can trigger a new generation of stars/clusters at their peripheries, with environmental conditions that may affect the initial mass function, disk evolution, and star formation efficiency. In this paper we study the stellar content and star formation processes in the young cluster Stock 8, which itself is thought to be formed during the expansion of a supershell. We present deep optical photometry along with JHK and 3.6 and 4.5 μ m photometry from UKIDSS and Spitzer -IRAC. We use multicolor criteria to identify the candidate young stellar objects in the region. Using evolutionary models,more » we obtain a median log(age) of ∼6.5 (∼3.0 Myr) with an observed age spread of ∼0.25 dex for the cluster. Monte Carlo simulations of the population of Stock 8, based on estimates for the photometric uncertainty, differential reddening, binarity, and variability, indicate that these uncertainties introduce an age spread of ∼0.15 dex. The intrinsic age spread in the cluster is ∼0.2 dex. The fraction of young stellar objects surrounded by disks is ∼35%. The K -band luminosity function of Stock 8 is similar to that of the Trapezium cluster. The initial mass function (IMF) of Stock 8 has a Salpeter-like slope at >0.5 M {sub ⊙} and flattens and peaks at ∼0.4 M {sub ⊙}, below which it declines into the substellar regime. Although Stock 8 is surrounded by several massive stars, there seems to be no severe environmental effect in the form of the IMF due to the proximity of massive stars around the cluster.« less

Mapping the Shores of the Brown Dwarf Desert. III. Young Moving Groups

NASA Astrophysics Data System (ADS)

Evans, T. M.; Ireland, M. J.; Kraus, A. L.; Martinache, F.; Stewart, P.; Tuthill, P. G.; Lacour, S.; Carpenter, J. M.; Hillenbrand, L. A.

2012-01-01

We present the results of an aperture-masking interferometry survey for substellar companions around 67 members of the young (~8-200 Myr) nearby (~5-86 pc) AB Doradus, β Pictoris, Hercules-Lyra, TW Hya, and Tucana-Horologium stellar associations. Observations were made at near-infrared wavelengths between 1.2 and 3.8 μm using the adaptive optics facilities of the Keck II, Very Large Telescope UT4, and Palomar Hale Telescopes. Typical contrast ratios of ~100-200 were achieved at angular separations between ~40 and 320 mas, with our survey being 100% complete for companions with masses below ~0.25 M ⊙ across this range. We report the discovery of a 0.52 ± 0.09 M ⊙ companion to HIP 14807, as well as the detections and orbits of previously known stellar companions to HD 16760, HD 113449, and HD 160934. We show that the companion to HD 16760 is in a face-on orbit, resulting in an upward revision of its mass from M 2sin i ~ 14 M J to M 2 = 0.28 ± 0.04 M ⊙. No substellar companions were detected around any of our sample members, despite our ability to detect companions with masses below 80 M J for 50 of our targets: of these, our sensitivity extended down to 40 M J around 30 targets, with a subset of 22 subject to the still more stringent limit of 20 M J. A statistical analysis of our non-detection of substellar companions allows us to place constraints on their frequency around ~0.2-1.5 M ⊙ stars. In particular, considering companion mass distributions that have been proposed in the literature, we obtain an upper limit estimate of ~9%-11% for the frequency of 20-80 M J companions between 3 and 30 AU at 95% confidence, assuming that their semimajor axes are distributed according to d {N}/da \\propto a^{-1} in this range.

Young Infants' Reasoning about Hidden Objects: Evidence from Violation-of-Expectation Tasks with Test Trials Only

ERIC Educational Resources Information Center

Wang, Su-hua; Baillargeon, Renee; Brueckner, Laura

2004-01-01

The present research examined alternative accounts of prior violation-of-expectation (VOE) reports that young infants can represent and reason about hidden objects. According to these accounts, young infants' apparent success in these VOE tasks reflects only novelty and familiarity preferences induced by the habituation or familiarization trials…

Companions and Environments of Low-Mass Stars: From Star-Forming Regions to the Field

NASA Astrophysics Data System (ADS)

Ward-Duong, Kimberly; Patience, Jenny; De Rosa, Robert J.; Bulger, Joanna; Rajan, Abhijith; Goodwin, Simon; Parker, Richard J.; McCarthy, Donald W.; Kulesa, Craig; van der Plas, Gerrit; Menard, Francois; Pinte, Christophe; Jackson, Alan Patrick; Bryden, Geoffrey; Turner, Neal J.; Harvey, Paul M.; Hales, Antonio

2017-01-01

We present results from two studies probing the multiplicity and environmental properties of low-mass stars: (1) The MinMs (M-dwarfs in Multiples) Survey, a large, volume-limited survey of 245 field M-dwarfs within 15 pc, and (2) the TBOSS (Taurus Boundary of Stellar/Substellar) Survey, an ongoing study of disk properties for the lowest-mass members within the Taurus star-forming region. The MinMs Survey provides new measurements of the companion star fraction, separation distribution, and mass ratio distribution for the nearest K7-M6 dwarfs, utilizing a combination of high-resolution adaptive optics imaging and digitized widefield archival plates to cover an unprecedented separation range of ~1-10,000 AU. Within these data, we also identify companions below the stellar/brown dwarf boundary, enabling characterization of the substellar companion population to low-mass field stars. For the much younger population in Taurus, we present results from ALMA Band 7 continuum observations of low-mass stellar and substellar Class II objects, spanning spectral types from M4-M7.75. The sub-millimeter detections of these disks provide key estimates of the dust mass in small grains, which is then assessed within the context of region age, environment, and viability for planet formation. This young population also includes a number of interesting young binary systems. Covering both young (1-2 Myr) and old (>5 Gyr) populations of low-mass stars, the results from these studies provide benchmark measurements on the population statistics of low-mass field stars, and on the early protoplanetary environments of their younger M-star counterparts.

Effect of Repetition Lag on Priming of Unfamiliar Visual Objects in Young and Older Adults

PubMed Central

Gordon, Leamarie T.; Soldan, Anja; Thomas, Ayanna K.; Stern, Yaakov

2013-01-01

Across three experiments, we examined the effect of repetition lag on priming of unfamiliar visual objects in healthy young and older adults. Multiple levels of lag were examined, ranging from short (one to four intervening stimuli) to long (50+ intervening stimuli). In each experiment, subjects viewed a series of new and repeated line drawings of objects and decided whether they depicted structurally possible or impossible figures. Experiment 1 and 2 found similar levels of priming in young and older adults at short and medium lags. At the longer repetition lags (∼20+ intervening stimuli), older adults showed less overall priming, as measured by reaction time facilitation, than young adults. This indicates that older adults can rapidly encode unfamiliar three-dimensional objects to support priming at shorter lags; however, they cannot maintain these representations over longer intervals. In addition to repetition lag, we also explored the relationship between priming and cognitive reserve, as measured by education and verbal intelligence. In the older adults, higher levels of cognitive reserve were associated with greater reaction time priming, suggesting that cognitive reserve may mediate the relationship between aging and priming. PMID:23276220

Selective attention affects conceptual object priming and recognition: a study with young and older adults.

PubMed

Ballesteros, Soledad; Mayas, Julia

2014-01-01

In the present study, we investigated the effects of selective attention at encoding on conceptual object priming (Experiment 1) and old-new recognition memory (Experiment 2) tasks in young and older adults. The procedures of both experiments included encoding and memory test phases separated by a short delay. At encoding, the picture outlines of two familiar objects, one in blue and the other in green, were presented to the left and to the right of fixation. In Experiment 1, participants were instructed to attend to the picture outline of a certain color and to classify the object as natural or artificial. After a short delay, participants performed a natural/artificial speeded conceptual classification task with repeated attended, repeated unattended, and new pictures. In Experiment 2, participants at encoding memorized the attended pictures and classify them as natural or artificial. After the encoding phase, they performed an old-new recognition memory task. Consistent with previous findings with perceptual priming tasks, we found that conceptual object priming, like explicit memory, required attention at encoding. Significant priming was obtained in both age groups, but only for those pictures that were attended at encoding. Although older adults were slower than young adults, both groups showed facilitation for attended pictures. In line with previous studies, young adults had better recognition memory than older adults.

Selective attention affects conceptual object priming and recognition: a study with young and older adults

PubMed Central

Ballesteros, Soledad; Mayas, Julia

2015-01-01

In the present study, we investigated the effects of selective attention at encoding on conceptual object priming (Experiment 1) and old–new recognition memory (Experiment 2) tasks in young and older adults. The procedures of both experiments included encoding and memory test phases separated by a short delay. At encoding, the picture outlines of two familiar objects, one in blue and the other in green, were presented to the left and to the right of fixation. In Experiment 1, participants were instructed to attend to the picture outline of a certain color and to classify the object as natural or artificial. After a short delay, participants performed a natural/artificial speeded conceptual classification task with repeated attended, repeated unattended, and new pictures. In Experiment 2, participants at encoding memorized the attended pictures and classify them as natural or artificial. After the encoding phase, they performed an old–new recognition memory task. Consistent with previous findings with perceptual priming tasks, we found that conceptual object priming, like explicit memory, required attention at encoding. Significant priming was obtained in both age groups, but only for those pictures that were attended at encoding. Although older adults were slower than young adults, both groups showed facilitation for attended pictures. In line with previous studies, young adults had better recognition memory than older adults. PMID:25628588

Protostellar Disk Instabilities and the Formation of Substellar Companions

NASA Astrophysics Data System (ADS)

Pickett, Brian K.; Durisen, Richard H.; Cassen, Patrick; Mejia, Annie C.

2000-09-01

Recent numerical simulations of self-gravitating protostellar disks have suggested that gravitational instabilities can lead to the production of substellar companions. In these simulations, the disk is typically assumed to be locally isothermal; i.e., the initial, axisymmetric temperature in the disk remains everywhere unchanged. Such an idealized condition implies extremely efficient cooling for outwardly moving parcels of gas. While we have seen disk disruption in our own locally isothermal simulations of a small, massive protostellar disk, no long-lived companions formed as a result of the instabilities. Instead, thermal and tidal effects and the complex interactions of the disk material prevented permanent condensations from forming, despite the vigorous growth of spiral instabilities. In order to compare our results more directly with those of other authors, we here present three-dimensional evolutions of an older, larger, but less massive protostellar disk. We show that potentially long-lived condensations form only for the extreme of local isothermality, and then only when severe restrictions are placed on the natural tendency of the protostellar disk to expand in response to gravitational instabilities. A more realistic adiabatic evolution leads to vertical and radial expansion of the disk but no clump formation. We conclude that isothermal disk calculations cannot demonstrate companion formation by disk fragmentation but only suggest it at best. It will be necessary in future numerical work on this problem to treat the disk thermodynamics more realistically.

Object permanence in young infants: further evidence.

PubMed

Baillargeon, R; DeVos, J

1991-12-01

Recent evidence suggests that 4.5- and even 3.5-month-old infants realize that objects continue to exist when hidden. The goal of the present experiments was to obtain converging evidence of object permanence in young infants. Experiments were conducted using paradigms previously used to demonstrate object permanence in 5.5-month-old infants and 6.5-month-old infants. In one experiment, 3.5-month-old infants watched a short or a tall carrot slide along a track. The track's center was hidden by a screen with a large window in its upper half. The short carrot was shorter than the window's lower edge and so did not appear in the window when passing behind the screen; the tall carrot was taller than the window's lower edge and hence should have appeared in the window but did not. The infants looked reliably longer at the tall than at the short carrot event, suggesting that they (a) represented the existence, height, and trajectory of each carrot behind the screen and (b) expected the tall carrot to appear in the screen window and were surprised that it did not. Control trials supported this interpretation. In another experiment, 4.0-month-old infants saw a toy car roll along a track that was partly hidden by a screen. A large toy mouse was placed behind the screen, either on top or in back of the track. The female infants looked reliably longer when the mouse stood on top as opposed to in back of the track, suggesting that they (a) represented the existence and trajectory of the car behind the screen, (b) represented the existence and location of the mouse behind the screen, and (c) were surprised to see the car reappear from behind the screen when the mouse stood in its path. A second experiment supported this interpretation. The results of these experiments provide further evidence that infants aged 3.5 months and older are able to represent and to reason about hidden objects.

Young Low-Mass Stars and Brown Dwarfs in IC 348

NASA Astrophysics Data System (ADS)

Luhman, K. L.

1999-11-01

I present new results from a continuing program to identify and characterize the low-mass stellar and substellar populations in the young cluster IC 348 (0.5-10 Myr). Optical spectroscopy has revealed young objects with spectral types as late as M8.25. The intrinsic J-H and H-K colors of these sources are dwarflike, whereas the R-I and I-J colors appear intermediate between the colors of dwarfs and giants. Furthermore, the spectra from 6500 to 9500 Å are reproduced well with averages of standard dwarf and giant spectra, suggesting that such averages should be used in the classification of young late-type sources. An H-R diagram is constructed for the low-mass population in IC 348 (K6-M8). The presumably coeval components of the young quadruple system GG Tau (White et al.) and the locus of stars in IC 348 are used as empirical isochrones to test the theoretical evolutionary models. The calculations of Burrows et al. do not appear to be consistent with the data at these earliest stages of stellar evolution. There is fair agreement between the data and the model isochrones of D'Antona & Mazzitelli, except near the hydrogen-burning limit. The agreement cannot be improved by changing the conversion between spectral types and effective temperatures. On the other hand, for the models of Baraffe et al., an adjustment of the temperature scale to progressively warmer temperatures at later M types, intermediate between dwarfs and giants, brings all components of GG Tau onto the same model isochrone and gives the population of IC 348 a constant age and age spread as a function of mass. When other observational constraints are considered, such as the dynamical masses of GM Aur, DM Tau, and GG Tau A, the models of Baraffe et al. are the most consistent with observations of young systems. With compatible temperature scales, the models of both D'Antona & Mazzitelli and Baraffe et al. suggest that the hydrogen-burning mass limit occurs near M6 at ages of <~10 Myr. Thus, several

Intact perception but abnormal orientation towards face-like objects in young children with ASD

PubMed Central

Guillon, Quentin; Rogé, Bernadette; Afzali, Mohammad H.; Baduel, Sophie; Kruck, Jeanne; Hadjikhani, Nouchine

2016-01-01

There is ample behavioral evidence of diminished orientation towards faces as well as the presence of face perception impairments in autism spectrum disorder (ASD), but the underlying mechanisms of these deficits are still unclear. We used face-like object stimuli that have been shown to evoke pareidolia in typically developing (TD) individuals to test the effect of a global face-like configuration on orientation and perceptual processes in young children with ASD and age-matched TD controls. We show that TD children were more likely to look first towards upright face-like objects than children with ASD, showing that a global face-like configuration elicit a stronger orientation bias in TD children as compared to children with ASD. However, once they were looking at the stimuli, both groups spent more time exploring the upright face-like object, suggesting that they both perceived it as a face. Our results are in agreement with abnormal social orienting in ASD, possibly due to an abnormal tuning of the subcortical pathway, leading to poor orienting and attention towards faces. Our results also indicate that young children with ASD can perceive a generic face holistically, such as face-like objects, further demonstrating holistic processing of faces in ASD. PMID:26912096

Intact perception but abnormal orientation towards face-like objects in young children with ASD.

PubMed

Guillon, Quentin; Rogé, Bernadette; Afzali, Mohammad H; Baduel, Sophie; Kruck, Jeanne; Hadjikhani, Nouchine

2016-02-25

There is ample behavioral evidence of diminished orientation towards faces as well as the presence of face perception impairments in autism spectrum disorder (ASD), but the underlying mechanisms of these deficits are still unclear. We used face-like object stimuli that have been shown to evoke pareidolia in typically developing (TD) individuals to test the effect of a global face-like configuration on orientation and perceptual processes in young children with ASD and age-matched TD controls. We show that TD children were more likely to look first towards upright face-like objects than children with ASD, showing that a global face-like configuration elicit a stronger orientation bias in TD children as compared to children with ASD. However, once they were looking at the stimuli, both groups spent more time exploring the upright face-like object, suggesting that they both perceived it as a face. Our results are in agreement with abnormal social orienting in ASD, possibly due to an abnormal tuning of the subcortical pathway, leading to poor orienting and attention towards faces. Our results also indicate that young children with ASD can perceive a generic face holistically, such as face-like objects, further demonstrating holistic processing of faces in ASD.

Atlas of low-mass young stellar object disks from mid-infrared interferometry

NASA Astrophysics Data System (ADS)

Varga, J.; Ábrahám, P.; Ratzka, Th.; Menu, J.; Gabányi, K.; Kóspál, Á.; van Boekel, R.; Mosoni, L.; Henning, Th.

We present our approach of visibility modeling of disks around low-mass (< 2 M ⊙) young stellar objects (YSOs). We compiled an atlas based on mid-infrared interferometric observations from the MIDI instrument at the VLTI. We use three different models to fit the data. These models allow us to determine overall sizes (and the extent of the inner gaps) of the modeled circumstellar disks.

A hot compact dust disk around a massive young stellar object.

PubMed

Kraus, Stefan; Hofmann, Karl-Heinz; Menten, Karl M; Schertl, Dieter; Weigelt, Gerd; Wyrowski, Friedrich; Meilland, Anthony; Perraut, Karine; Petrov, Romain; Robbe-Dubois, Sylvie; Schilke, Peter; Testi, Leonardo

2010-07-15

Circumstellar disks are an essential ingredient of the formation of low-mass stars. It is unclear, however, whether the accretion-disk paradigm can also account for the formation of stars more massive than about 10 solar masses, in which strong radiation pressure might halt mass infall. Massive stars may form by stellar merging, although more recent theoretical investigations suggest that the radiative-pressure limit may be overcome by considering more complex, non-spherical infall geometries. Clear observational evidence, such as the detection of compact dusty disks around massive young stellar objects, is needed to identify unambiguously the formation mode of the most massive stars. Here we report near-infrared interferometric observations that spatially resolve the astronomical-unit-scale distribution of hot material around a high-mass ( approximately 20 solar masses) young stellar object. The image shows an elongated structure with a size of approximately 13 x 19 astronomical units, consistent with a disk seen at an inclination angle of approximately 45 degrees . Using geometric and detailed physical models, we found a radial temperature gradient in the disk, with a dust-free region less than 9.5 astronomical units from the star, qualitatively and quantitatively similar to the disks observed in low-mass star formation. Perpendicular to the disk plane we observed a molecular outflow and two bow shocks, indicating that a bipolar outflow emanates from the inner regions of the system.

Very Low-mass Stellar and Substellar Companions to Solar-like Stars from MARVELS. VI. A Giant Planet and a Brown Dwarf Candidate in a Close Binary System HD 87646

NASA Astrophysics Data System (ADS)

Ma, Bo; Ge, Jian; Wolszczan, Alex; Muterspaugh, Matthew W.; Lee, Brian; Henry, Gregory W.; Schneider, Donald P.; Martín, Eduardo L.; Niedzielski, Andrzej; Xie, Jiwei; Fleming, Scott W.; Thomas, Neil; Williamson, Michael; Zhu, Zhaohuan; Agol, Eric; Bizyaev, Dmitry; Nicolaci da Costa, Luiz; Jiang, Peng; Martinez Fiorenzano, A. F.; González Hernández, Jonay I.; Guo, Pengcheng; Grieves, Nolan; Li, Rui; Liu, Jane; Mahadevan, Suvrath; Mazeh, Tsevi; Nguyen, Duy Cuong; Paegert, Martin; Sithajan, Sirinrat; Stassun, Keivan; Thirupathi, Sivarani; van Eyken, Julian C.; Wan, Xiaoke; Wang, Ji; Wisniewski, John P.; Zhao, Bo; Zucker, Shay

2016-11-01

We report the detections of a giant planet (MARVELS-7b) and a brown dwarf (BD) candidate (MARVELS-7c) around the primary star in the close binary system, HD 87646. To the best of our knowledge, it is the first close binary system with more than one substellar circumprimary companion that has been discovered. The detection of this giant planet was accomplished using the first multi-object Doppler instrument (KeckET) at the Sloan Digital Sky Survey (SDSS) telescope. Subsequent radial velocity observations using the Exoplanet Tracker at the Kitt Peak National Observatory, the High Resolution Spectrograph at the Hobby Eberley telescope, the “Classic” spectrograph at the Automatic Spectroscopic Telescope at the Fairborn Observatory, and MARVELS from SDSS-III confirmed this giant planet discovery and revealed the existence of a long-period BD in this binary. HD 87646 is a close binary with a separation of ˜22 au between the two stars, estimated using the Hipparcos catalog and our newly acquired AO image from PALAO on the 200 inch Hale Telescope at Palomar. The primary star in the binary, HD 87646A, has {T}{eff} = 5770 ± 80 K, log g = 4.1 ± 0.1, and [Fe/H] = -0.17 ± 0.08. The derived minimum masses of the two substellar companions of HD 87646A are 12.4 ± 0.7 {M}{Jup} and 57.0 ± 3.7 {M}{Jup}. The periods are 13.481 ± 0.001 days and 674 ± 4 days and the measured eccentricities are 0.05 ± 0.02 and 0.50 ± 0.02 respectively. Our dynamical simulations show that the system is stable if the binary orbit has a large semimajor axis and a low eccentricity, which can be verified with future astrometry observations.

ROTATION PERIODS OF YOUNG BROWN DWARFS: K2 SURVEY IN UPPER SCORPIUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scholz, Alexander; Kostov, Veselin; Jayawardhana, Ray

2015-08-20

We report rotational periods for 16 young brown dwarfs in the nearby Upper Scorpius association, based on 72 days of high-cadence, high-precision photometry from the Keplerspace telescope’s K2 mission. The periods range from a few hours to two days (plus one outlier at five days), with a median just above one day, confirming that brown dwarfs, except at the very youngest ages, are fast rotators. Interestingly, four of the slowest rotators in our sample exhibit mid-infrared excess emission from disks; at least two also show signs of disk eclipses and accretion in the light curves. Comparing these new periods withmore » those for two other young clusters and simple angular momentum evolution tracks, we find little or no rotational braking in brown dwarfs between 1–10 Myr, in contrast to low-mass stars. Our findings show that disk braking, while still at work, is inefficient in the substellar regime, thus providing an important constraint on the mass dependence of the braking mechanism.« less

An intermediate luminosity optical transient (ILOTs) model for the young stellar object ASASSN-15qi

NASA Astrophysics Data System (ADS)

Kashi, Amit; Soker, Noam

2017-07-01

We construct a scenario where the outburst of the young stellar object ASASSN-15qi is an intermediate luminosity optical transient (ILOT). In this scenario, a sub-Jupiter young planet was tidally destructed on to a young main-sequence (MS) star. The system is young, and therefore the radius of the planet is larger than its final value; consequently, its density is smaller. The lower density allows the tidal destruction of the young Saturn-like planet on to the MS star of mass ≈2.4 M⊙, resulting in the formation of a disc and a gravitationally powered ILOT. Unlike the case of the more energetic ILOT V838 Mon, the mass of the destructed planet is too low to inflate a giant envelope, and hence the merger remnant remains hot. If our suggested model holds, this ILOT possesses two interesting properties: (I) its luminosity and total energy are below those of novae; (II) it is not as red as other ILOTs. The unusual outburst of ASASSN-15qi - if indeed is an ILOT - further increases the diversity of the already heterogeneous group of ILOTs. We mark the region on the energy-time diagram occupied by such young ILOTs.

MAPPING THE SHORES OF THE BROWN DWARF DESERT. III. YOUNG MOVING GROUPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, T. M.; Ireland, M. J.; Stewart, P.

2012-01-10

We present the results of an aperture-masking interferometry survey for substellar companions around 67 members of the young ({approx}8-200 Myr) nearby ({approx}5-86 pc) AB Doradus, {beta} Pictoris, Hercules-Lyra, TW Hya, and Tucana-Horologium stellar associations. Observations were made at near-infrared wavelengths between 1.2 and 3.8 {mu}m using the adaptive optics facilities of the Keck II, Very Large Telescope UT4, and Palomar Hale Telescopes. Typical contrast ratios of {approx}100-200 were achieved at angular separations between {approx}40 and 320 mas, with our survey being 100% complete for companions with masses below {approx}0.25 M{sub Sun} across this range. We report the discovery of amore » 0.52 {+-} 0.09 M{sub Sun} companion to HIP 14807, as well as the detections and orbits of previously known stellar companions to HD 16760, HD 113449, and HD 160934. We show that the companion to HD 16760 is in a face-on orbit, resulting in an upward revision of its mass from M{sub 2}sin i {approx} 14 M{sub J} to M{sub 2} = 0.28 {+-} 0.04 M{sub Sun }. No substellar companions were detected around any of our sample members, despite our ability to detect companions with masses below 80 M{sub J} for 50 of our targets: of these, our sensitivity extended down to 40 M{sub J} around 30 targets, with a subset of 22 subject to the still more stringent limit of 20 M{sub J}. A statistical analysis of our non-detection of substellar companions allows us to place constraints on their frequency around {approx}0.2-1.5 M{sub Sun} stars. In particular, considering companion mass distributions that have been proposed in the literature, we obtain an upper limit estimate of {approx}9%-11% for the frequency of 20-80 M{sub J} companions between 3 and 30 AU at 95% confidence, assuming that their semimajor axes are distributed according to dN/da{proportional_to}a{sup -1} in this range.« less

The `DODO' survey - I. Limits on ultra-cool substellar and planetary-mass companions to van Maanen's star (vMa2)

NASA Astrophysics Data System (ADS)

Burleigh, M. R.; Clarke, F. J.; Hogan, E.; Brinkworth, C. S.; Bergeron, P.; Dufour, P.; Dobbie, P. D.; Levan, A. J.; Hodgkin, S. T.; Hoard, D. W.; Wachter, S.

2008-05-01

We report limits in the planetary-mass regime for companions around the nearest single white dwarf to the Sun, van Maanen's star (vMa2), from deep J-band imaging with Gemini North and Spitzer Infrared Array Camera (IRAC) mid-IR photometry. We find no resolved common proper motion companions to vMa2 at separations from 3 to 45 arcsec, at a limiting magnitude of J ~ 23. Assuming a total age for the system of 4.1 +/- 1Gyr, and utilizing the latest evolutionary models for substellar objects, this limit is equivalent to companion masses >7 +/- 1MJup(Teff ~ 300K). Taking into account the likely orbital evolution of very low mass companions in the post-main-sequence phase, these J-band observations effectively survey orbits around the white dwarf progenitor from 3 to 50au. There is no flux excess detected in any of the complimentary Spitzer IRAC mid-IR filters. We fit a white dwarf model atmosphere to the optical BVRI, JHK and IRAC photometry. The best solution gives Teff = 6030 +/- 240K, logg = 8.10 +/- 0.04 and, hence, M = 0.633 +/- 0.022Msolar. We then place a 3σ upper limit of 10 +/- 2MJup on the mass of any unresolved companion in the 4.5μm band.

The First X-shooter Observations of Jets from Young Stars

NASA Astrophysics Data System (ADS)

Bacciotti, F.; Whelan, E. T.; Alcalá, J. M.; Nisini, B.; Podio, L.; Randich, S.; Stelzer, B.; Cupani, G.

2011-08-01

We present the first pilot study of jets from young stars conducted with X-shooter, on the ESO/Very Large Telescope. As it offers simultaneous, high-quality spectra in the range 300-2500 nm, X-shooter is uniquely important for spectral diagnostics in jet studies. We chose to probe the accretion/ejection mechanisms at low stellar masses examining two targets with well-resolved continuous jets lying on the plane of the sky: ESO-HA 574 in Chameleon I and Par-Lup3-4 in Lupus III. The mass of the latter is close to the sub-stellar boundary (M sstarf = 0.13 M sun). A large number of emission lines probing regions of different excitation are identified, position-velocity diagrams are presented, and mass outflow/accretion rates are estimated. Comparison between the two objects is striking. ESO-HA 574 is a weakly accreting star for which we estimate a mass accretion rate of log (\\dot{M}_{acc}) = -10.8 +/- 0.5 (in M sun yr-1), yet it drives a powerful jet with \\dot{M}_{out} ~ 1.5-2.7 × 10-9 M sun yr-1. These values can be reconciled with a magneto-centrifugal jet acceleration mechanism assuming that the presence of the edge-on disk severely depresses the luminosity of the accretion tracers. In comparison, Par-Lup3-4, with stronger mass accretion (log (\\dot{M}_{acc}) = -9.1 +/- 0.4 M sun yr-1), drives a low-excitation jet with about \\dot{M}_{out} ~ 3.2 × 10-10 M sun yr-1 in both lobes. Despite the low stellar mass, \\dot{M}_{out}/\\dot{M}_{acc} for Par-Lup3-4 is at the upper limit of the range usually measured for young objects, but still compatible with a steady magneto-centrifugal wind scenario if all uncertainties are considered. Based on Observations collected with X-shooter at the Very Large Telescope on Cerro Paranal (Chile), operated by the European Southern Observatory (ESO). Program ID: 085.C-0238(A).

SED Modeling of 20 Massive Young Stellar Objects

NASA Astrophysics Data System (ADS)

Tanti, Kamal Kumar

In this paper, we present the spectral energy distributions (SEDs) modeling of twenty massive young stellar objects (MYSOs) and subsequently estimated different physical and structural/geometrical parameters for each of the twenty central YSO outflow candidates, along with their associated circumstellar disks and infalling envelopes. The SEDs for each of the MYSOs been reconstructed by using 2MASS, MSX, IRAS, IRAC & MIPS, SCUBA, WISE, SPIRE and IRAM data, with the help of a SED Fitting Tool, that uses a grid of 2D radiative transfer models. Using the detailed analysis of SEDs and subsequent estimation of physical and geometrical parameters for the central YSO sources along with its circumstellar disks and envelopes, the cumulative distribution of the stellar, disk and envelope parameters can be analyzed. This leads to a better understanding of massive star formation processes in their respective star forming regions in different molecular clouds.

X-ray sources associated with young stellar objects in the star formation region CMa R1

NASA Astrophysics Data System (ADS)

Santos-Silva, Thais; Gregorio-Hetem, Jane; Montmerle, Thierry

2013-07-01

In previous works we studied the star formation scenario in the molecular cloud Canis Major R1 (CMa R1), derived from the existence of young stellar population groups near the Be stars Z CMa and GU CMa. Using data from the ROSAT X-ray satellite, having a field-of-view of ~ 1° in diameter, Gregorio-Hetem et al. (2009) discovered in this region young stellar objects mainly grouped in two clusters of different ages, with others located in between. In order to investigate the nature of these objects and to test a possible scenario of sequential star formation in this region, four fields (each 30 arcmin diameter, with some overlap) have been observed with the XMM-Newton satellite, with a sensitivity about 10 times better than ROSAT. The XMM-Newton data are currently under analysis. Preliminary results indicate the presence of about 324 sources, most of them apparently having one or more near-infrared counterparts showing typical colors of young stars. The youth of the X-ray sources was also confirmed by X-ray hardness ratio diagrams (XHRD), in different energy bands, giving an estimate of their Lx/Lbol ratios. In addition to these results, we present a detailed study of the XMM field covering the cluster near Z CMa. Several of these sources were classified as T Tauri and Herbig Ae/Be stars, using optical spectroscopy obtained with Gemini telescopes, in order to validate the use of XHRD applied to the entire sample. This classification is also used to confirm the relation between the luminosities in the near-infrared and X-ray bands expected for the T Tauri stars in CMa R1. In the present work we show the results of the study based on the spectra of about 90 sources found nearby Z CMa. We checked that the X-ray spectra (0.3 to 10 keV) of young objects is different from that observed in field stars and extragalactic objects. Some of the candidates also have light curve showing flares that are typical of T Tauri stars, which confirms the young nature of these X

Warm gas towards young stellar objects in Corona Australis. Herschel/PACS observations from the DIGIT key programme

NASA Astrophysics Data System (ADS)

Lindberg, Johan E.; Jørgensen, Jes K.; Green, Joel D.; Herczeg, Gregory J.; Dionatos, Odysseas; Evans, Neal J.; Karska, Agata; Wampfler, Susanne F.

2014-05-01

Context. The effects of external irradiation on the chemistry and physics in the protostellar envelope around low-mass young stellar objects are poorly understood. The Corona Australis star-forming region contains the R CrA dark cloud, comprising several low-mass protostellar cores irradiated by an intermediate-mass young star. Aims: We study the effects of the irradiation coming from the young luminous Herbig Be star R CrA on the warm gas and dust in a group of low-mass young stellar objects. Methods: Herschel/PACS far-infrared datacubes of two low-mass star-forming regions in the R CrA dark cloud are presented. The distributions of CO, OH, H2O, [C ii], [O i], and continuum emission are investigated. We have developed a deconvolution algorithm which we use to deconvolve the maps, separating the point-source emission from the extended emission. We also construct rotational diagrams of the molecular species. Results: By deconvolution of the Herschel data, we find large-scale (several thousand AU) dust continuum and spectral line emission not associated with the point sources. Similar rotational temperatures are found for the warm CO (282 ± 4 K), hot CO (890 ± 84 K), OH (79 ± 4 K), and H2O (197 ± 7 K) emission in the point sources and the extended emission. The rotational temperatures are also similar to those found in other more isolated cores. The extended dust continuum emission is found in two ridges similar in extent and temperature to molecular millimetre emission, indicative of external heating from the Herbig Be star R CrA. Conclusions: Our results show that nearby luminous stars do not increase the molecular excitation temperatures of the warm gas around young stellar objects (YSOs). However, the emission from photodissociation products of H2O, such as OH and O, is enhanced in the warm gas associated with these protostars and their surroundings compared to similar objects not subjected to external irradiation. Table 9 and appendices are available in

On the local standard of rest. [comoving with young objects in gravitational field of spiral galaxies

NASA Technical Reports Server (NTRS)

Yuan, C.

1983-01-01

Under the influence of a spiral gravitational field, there should be differences among the mean motions of different types of objects with different dispersion velocities in a spiral galaxy. The old stars with high dispersion velocity should have essentially no mean motion normal to the galactic rotation. On the other hand, young objects and interstellar gas may be moving relative to the old stars at a velocity of a few kilometer per second in both the radial (galacto-centric), and circular directions, depending on the spiral model adopted. Such a velocity is usually referred as the systematic motion or the streaming motion. The conventionally adopted local standard of rest is indeed co-moving with the young objects of the solar vicinity. Therefore, it has a net systematic motion with respect to the circular motion of an equilibrium galactic model, defined by the old stars. Previously announced in STAR as N83-24443

CO-ices in embedded Young Stellar Objects

NASA Astrophysics Data System (ADS)

Teixeira, Teresa Cláeira V. S.

1998-09-01

Stars are born in dense cores within molecular clouds, enshrouded in large cocoons of gas and dust which completely obscure the forming star. The large degree of obscuration towards the young stars is due to the presence of solid dust grains in their circumstellar envelopes, which efficiently absorb the radiation from the star at visual and ultraviolet wavelengths, reradiating that energy at far-infrared and submillimeter wavelengths. The composition and structure of the dust grains is not well known, but current studies point to grains having a refractory core and acquiring ice mantles in the cool, shielded conditions of molecular clouds. Such ice mantles are the subject of this thesis. Infrared spectroscopy is an important tool in the study of the complex ice mantles on interstellar grains. A variety of absorption features at these wavelengths, which have been identified as the vibrational transitions of the molecules in the ices, can provide important information on the composition, structure and evolution of the grains. The work reported in this thesis consists of an observational study of the composition of the ice mantles acquired by the dust grains in molecular clouds (with particular emphasis on the CO-ices in the material surrounding embedded Young Stellar Objects in nearby molecular clouds), what can be learned from that about the physical conditions in the regions where the ice mantles exist, and what may affect their survival and evolution. In this work, spectra of the 4.67 micron solid CO absorption feature are presented, mostly towards embedded objects in Taurus. The thesis starts with a brief overview of technical aspects of spectroscopic observations at thermal infrared wavelengths, where the CO stretch absorption feature is located. The observations and data reduction procedures are then reported and discussed in detail. The likely composition of the CO-bearing ices is analysed by fitting the observations with laboratory data. The statistical

FUNDAMENTAL PARAMETERS AND SPECTRAL ENERGY DISTRIBUTIONS OF YOUNG AND FIELD AGE OBJECTS WITH MASSES SPANNING THE STELLAR TO PLANETARY REGIME

DOE Office of Scientific and Technical Information (OSTI.GOV)

Filippazzo, Joseph C.; Rice, Emily L.; Faherty, Jacqueline

We combine optical, near-infrared, and mid-infrared spectra and photometry to construct expanded spectral energy distributions for 145 field age (>500 Myr) and 53 young (lower age estimate <500 Myr) ultracool dwarfs (M6-T9). This range of spectral types includes very low mass stars, brown dwarfs, and planetary mass objects, providing fundamental parameters across both the hydrogen and deuterium burning minimum masses for the largest sample assembled to date. A subsample of 29 objects have well constrained ages as probable members of a nearby young moving group. We use 182 parallaxes and 16 kinematic distances to determine precise bolometric luminosities (L{sub bol})more » and radius estimates from evolutionary models give semi-empirical effective temperatures (T{sub eff}) for the full range of young and field age late-M, L, and T dwarfs. We construct age-sensitive relationships of luminosity, temperature, and absolute magnitude as functions of spectral type and absolute magnitude to disentangle the effects of degenerate physical parameters such as T{sub eff}, surface gravity, and clouds on spectral morphology. We report bolometric corrections in J for both field age and young objects and find differences of up to a magnitude for late-L dwarfs. Our correction in Ks shows a larger dispersion but not necessarily a different relationship for young and field age sequences. We also characterize the NIR–MIR reddening of low gravity L dwarfs and identify a systematically cooler T{sub eff} of up to 300 K from field age objects of the same spectral type and 400 K cooler from field age objects of the same M{sub H} magnitude.« less

Lithium in Open Cluster Red Giants Hosting Substellar Companions

NASA Technical Reports Server (NTRS)

Carlberg, Joleen K.; Smith, Verne V.; Cunha, Katia; Carpenter, Kenneth G.

2016-01-01

We have measured stellar parameters, [Fe/H], lithium abundances, rotation, and (12)C/13C in a small sample of red giants (RGs) in three open clusters that are each home to a RG star that hosts a substellar companion (SSC) (NGC 2423 3, NGC 4349 127, and BD+12 1917 in M67). Our goal is to explore whether the presence of SSCs influences the Li content. Both (12)C/13C and stellar rotation are measured as additional tracers of stellar mixing. One of the companion hosts, NGC 2423?3, is found to be Li-rich with A(Li)(sub NLTE) = 1.56 dex, and this abundance is significantly higher than the A(Li) of the two comparison stars in NGC 2423. All three SSC hosts have the highest A(Li) and (12)C/13C when compared to the control RGs in their respective clusters; however, except for NGC 2423?3, at least one control star has similarly high abundances within the uncertainties. Higher A(Li) could suggest that the formation or presence of planets plays a role in the degree of internal mixing on or before the RG branch. However, a multitude of factors affect A(Li) during the RG phase, and when the abundances of our sample are compared with the abundances of RGs in other open clusters available in the literature, we find that they all fall well within a much larger distribution of A(Li) and (12)C/13C. Thus, even the high Li in NGC 2423 3 cannot be concretely tied to the presence of the SSC.

Lithium in Open Cluster Red Giants Hosting Substellar Companions

NASA Astrophysics Data System (ADS)

Carlberg, Joleen K.; Smith, Verne V.; Cunha, Katia; Carpenter, Kenneth G.

2016-02-01

We have measured stellar parameters, [Fe/H], lithium abundances, rotation, and 12C/13C in a small sample of red giants (RGs) in three open clusters that are each home to a RG star that hosts a substellar companion (SSC) (NGC 2423 3, NGC 4349 127, and BD+12 1917 in M67). Our goal is to explore whether the presence of SSCs influences the Li content. Both 12C/13C and stellar rotation are measured as additional tracers of stellar mixing. One of the companion hosts, NGC 2423 3, is found to be Li-rich with A(Li){}{{NLTE}} = 1.56 dex, and this abundance is significantly higher than the A(Li) of the two comparison stars in NGC 2423. All three SSC hosts have the highest A(Li) and 12C/13C when compared to the control RGs in their respective clusters; however, except for NGC 2423 3, at least one control star has similarly high abundances within the uncertainties. Higher A(Li) could suggest that the formation or presence of planets plays a role in the degree of internal mixing on or before the RG branch. However, a multitude of factors affect A(Li) during the RG phase, and when the abundances of our sample are compared with the abundances of RGs in other open clusters available in the literature, we find that they all fall well within a much larger distribution of A(Li) and 12C/13C. Thus, even the high Li in NGC 2423 3 cannot be concretely tied to the presence of the SSC.

SIM PlanetQuest Key Project Precursor Observations to Detect Gas Giant Planets Around Young Stars

NASA Technical Reports Server (NTRS)

Tanner, Angelle; Beichman, Charles; Akeson, Rachel; Ghez, Andrea; Grankin, Konstantin N.; Herbst, William; Hillenbrand, Lynne; Huerta, Marcos; Konopacky, Quinn; Metchev, Stanimir;

YOUNG STELLAR OBJECTS IN THE GOULD BELT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunham, Michael M.; Allen, Lori E.; Evans II, Neal J.

2015-09-15

We present the full catalog of Young Stellar Objects (YSOs) identified in the 18 molecular clouds surveyed by the Spitzer Space Telescope “cores to disks” (c2d) and “Gould Belt” (GB) Legacy surveys. Using standard techniques developed by the c2d project, we identify 3239 candidate YSOs in the 18 clouds, 2966 of which survive visual inspection and form our final catalog of YSOs in the GB. We compile extinction corrected spectral energy distributions for all 2966 YSOs and calculate and tabulate the infrared spectral index, bolometric luminosity, and bolometric temperature for each object. We find that 326 (11%), 210 (7%), 1248more » (42%), and 1182 (40%) are classified as Class 0 + I, Flat-spectrum, Class II, and Class III, respectively, and show that the Class III sample suffers from an overall contamination rate by background Asymptotic Giant Branch stars between 25% and 90%. Adopting standard assumptions, we derive durations of 0.40–0.78 Myr for Class 0 + I YSOs and 0.26–0.50 Myr for Flat-spectrum YSOs, where the ranges encompass uncertainties in the adopted assumptions. Including information from (sub)millimeter wavelengths, one-third of the Class 0 + I sample is classified as Class 0, leading to durations of 0.13–0.26 Myr (Class 0) and 0.27–0.52 Myr (Class I). We revisit infrared color–color diagrams used in the literature to classify YSOs and propose minor revisions to classification boundaries in these diagrams. Finally, we show that the bolometric temperature is a poor discriminator between Class II and Class III YSOs.« less

PLANETS AROUND LOW-MASS STARS (PALMS). V. AGE-DATING LOW-MASS COMPANIONS TO MEMBERS AND INTERLOPERS OF YOUNG MOVING GROUPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowler, Brendan P.; Montet, Benjamin T.; Riddle, Reed

2015-06-10

We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7–M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8–120 Myr) in the literature. Three of these are new companions identified in our AO imaging survey, and two others are confirmed to be comoving with their host stars for the first time. The inferred masses of the companions (∼10–100 M{sub Jup}) are highly sensitive to the ages of the primary stars; therefore we critically examine the kinematic and spectroscopic properties of each systemmore » to distinguish bona fide YMG members from old field interlopers. The new M7 substellar companion 2MASS J02155892–0929121 C (40–60 M{sub Jup}) shows clear spectroscopic signs of low gravity and, hence, youth. The primary, possibly a member of the ∼40 Myr Tuc-Hor moving group, is visually resolved into three components, making it a young low-mass quadruple system in a compact (≲100 AU) configuration. In addition, Li i λ6708 absorption in the intermediate-gravity M7.5 companion 2MASS J15594729+4403595 B provides unambiguous evidence that it is young (≲200 Myr) and resides below the hydrogen-burning limit. Three new close-separation (<1″) companions (2MASS J06475229–2523304 B, PYC J11519+0731 B, and GJ 4378 Ab) orbit stars previously reported as candidate YMG members, but instead are likely old (≳1 Gyr) tidally locked spectroscopic binaries without convincing kinematic associations with any known moving group. The high rate of false positives in the form of old active stars with YMG-like kinematics underscores the importance of radial velocity and parallax measurements to validate candidate young stars identified via proper motion and activity selection alone. Finally, we spectroscopically confirm the cool temperature and substellar nature of HD 23514 B, a recently discovered M8 benchmark brown dwarf orbiting

Planets Around Low-mass Stars (PALMS). V. Age-dating Low-mass Companions to Members and Interlopers of Young Moving Groups

NASA Astrophysics Data System (ADS)

Bowler, Brendan P.; Shkolnik, Evgenya L.; Liu, Michael C.; Schlieder, Joshua E.; Mann, Andrew W.; Dupuy, Trent J.; Hinkley, Sasha; Crepp, Justin R.; Johnson, John Asher; Howard, Andrew W.; Flagg, Laura; Weinberger, Alycia J.; Aller, Kimberly M.; Allers, Katelyn N.; Best, William M. J.; Kotson, Michael C.; Montet, Benjamin T.; Herczeg, Gregory J.; Baranec, Christoph; Riddle, Reed; Law, Nicholas M.; Nielsen, Eric L.; Wahhaj, Zahed; Biller, Beth A.; Hayward, Thomas L.

2015-06-01

We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7-M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8-120 Myr) in the literature. Three of these are new companions identified in our AO imaging survey, and two others are confirmed to be comoving with their host stars for the first time. The inferred masses of the companions (˜10-100 MJup) are highly sensitive to the ages of the primary stars; therefore we critically examine the kinematic and spectroscopic properties of each system to distinguish bona fide YMG members from old field interlopers. The new M7 substellar companion 2MASS J02155892-0929121 C (40-60 MJup) shows clear spectroscopic signs of low gravity and, hence, youth. The primary, possibly a member of the ˜40 Myr Tuc-Hor moving group, is visually resolved into three components, making it a young low-mass quadruple system in a compact (≲100 AU) configuration. In addition, Li i λ6708 absorption in the intermediate-gravity M7.5 companion 2MASS J15594729+4403595 B provides unambiguous evidence that it is young (≲200 Myr) and resides below the hydrogen-burning limit. Three new close-separation (<1″) companions (2MASS J06475229-2523304 B, PYC J11519+0731 B, and GJ 4378 Ab) orbit stars previously reported as candidate YMG members, but instead are likely old (≳1 Gyr) tidally locked spectroscopic binaries without convincing kinematic associations with any known moving group. The high rate of false positives in the form of old active stars with YMG-like kinematics underscores the importance of radial velocity and parallax measurements to validate candidate young stars identified via proper motion and activity selection alone. Finally, we spectroscopically confirm the cool temperature and substellar nature of HD 23514 B, a recently discovered M8 benchmark brown dwarf orbiting the dustiest-known member of the

NIR integral field spectroscopy of high mass young stellar objects

NASA Astrophysics Data System (ADS)

Murakawa, K.; Lumsden, S. L.; Oudmaijer, R. D.; Davies, B.; Hoare, M. G.

2013-03-01

We present K-band Integral Field Spectroscopy of six high mass young stellar objects (IRAS~18151-1208, AFGL~2136, S106~IRS4, V645 Cyg, IRAS~19065+0526, and G082.5682+ 00.4040) obtained using the adaptive optics assisted NIFS instrument mounted on the Gemini North telescope. The targets are chosen from the Red MSX Source survey led by University of Leeds. The data show the spectral features of Brγ, H2, and gas phase CO emissions and absorptions with a spectral resolution of R ≈ 5500, which allow a three-dimensional spectro-astrometric analysis of the line emissions. We discuss the results of the ionized jets and winds, and rotating CO torus.

Increased objectively assessed vigorous-intensity exercise is associated with reduced stress, increased mental health and good objective and subjective sleep in young adults.

PubMed

Gerber, Markus; Brand, Serge; Herrmann, Christian; Colledge, Flora; Holsboer-Trachsler, Edith; Pühse, Uwe

2014-08-01

The role of physical activity as a factor that protects against stress-related mental disorders is well documented. Nevertheless, there is still a dearth of research using objective measures of physical activity. The present study examines whether objectively assessed vigorous physical activity (VPA) is associated with mental health benefits beyond moderate physical activity (MPA). Particularly, this study examines whether young adults who accomplish the American College of Sports Medicine's (ACSM) vigorous-intensity exercise recommendations differ from peers below these standards with regard to their level of perceived stress, depressive symptoms, perceived pain, and subjective and objective sleep. A total of 42 undergraduate students (22 women, 20 men; M=21.24years, SD=2.20) volunteered to take part in the study. Stress, pain, depressive symptoms, and subjective sleep were assessed via questionnaire, objective sleep via sleep-EEG assessment, and VPA via actigraphy. Meeting VPA recommendations had mental health benefits beyond MPA. VPA was associated with less stress, pain, subjective sleep complaints and depressive symptoms. Moreover, vigorous exercisers had more favorable objective sleep pattern. Especially, they had increased total sleep time, more stage 4 and REM sleep, more slow wave sleep and a lower percentage of light sleep. Vigorous exercisers also reported fewer mental health problems if exposed to high stress. This study provides evidence that meeting the VPA standards of the ACSM is associated with improved mental health and more successful coping among young people, even compared to those who are meeting or exceeding the requirements for MPA. Copyright © 2014 Elsevier Inc. All rights reserved.

The Use of Play Expansions to Increase the Diversity and Complexity of Object Play in Young Children with Disabilities

ERIC Educational Resources Information Center

Frey, Jennifer R.; Kaiser, Ann P.

2011-01-01

The purpose of this study was to determine if an intervention consisting of contingently imitating play, modeling expansions of play actions, and describing play actions increased the diversity of object play in young children with disabilities. The multicomponent intervention was introduced in a multiple-probe design across three young children…

Accretion-induced variability links young stellar objects, white dwarfs, and black holes.

PubMed

Scaringi, Simone; Maccarone, Thomas J; Körding, Elmar; Knigge, Christian; Vaughan, Simon; Marsh, Thomas R; Aranzana, Ester; Dhillon, Vikram S; Barros, Susana C C

2015-10-01

The central engines of disc-accreting stellar-mass black holes appear to be scaled down versions of the supermassive black holes that power active galactic nuclei. However, if the physics of accretion is universal, it should also be possible to extend this scaling to other types of accreting systems, irrespective of accretor mass, size, or type. We examine new observations, obtained with Kepler/K2 and ULTRACAM, regarding accreting white dwarfs and young stellar objects. Every object in the sample displays the same linear correlation between the brightness of the source and its amplitude of variability (rms-flux relation) and obeys the same quantitative scaling relation as stellar-mass black holes and active galactic nuclei. We also show that the most important parameter in this scaling relation is the physical size of the accreting object. This establishes the universality of accretion physics from proto-stars still in the star-forming process to the supermassive black holes at the centers of galaxies.

Accretion-induced variability links young stellar objects, white dwarfs, and black holes

PubMed Central

Scaringi, Simone; Maccarone, Thomas J.; Körding, Elmar; Knigge, Christian; Vaughan, Simon; Marsh, Thomas R.; Aranzana, Ester; Dhillon, Vikram S.; Barros, Susana C. C.

2015-01-01

The central engines of disc-accreting stellar-mass black holes appear to be scaled down versions of the supermassive black holes that power active galactic nuclei. However, if the physics of accretion is universal, it should also be possible to extend this scaling to other types of accreting systems, irrespective of accretor mass, size, or type. We examine new observations, obtained with Kepler/K2 and ULTRACAM, regarding accreting white dwarfs and young stellar objects. Every object in the sample displays the same linear correlation between the brightness of the source and its amplitude of variability (rms-flux relation) and obeys the same quantitative scaling relation as stellar-mass black holes and active galactic nuclei. We also show that the most important parameter in this scaling relation is the physical size of the accreting object. This establishes the universality of accretion physics from proto-stars still in the star-forming process to the supermassive black holes at the centers of galaxies. PMID:26601307

Spectroscopic Confirmation of Young Planetary-mass Companions on Wide Orbits

NASA Astrophysics Data System (ADS)

Bowler, Brendan P.; Liu, Michael C.; Kraus, Adam L.; Mann, Andrew W.

2014-03-01

We present moderate-resolution (R ~ 4000-5000) near-infrared integral field spectroscopy of the young (1-5 Myr) 6-14 M Jup companions ROXs 42B b and FW Tau b obtained with Keck/OSIRIS and Gemini-North/NIFS. The spectrum of ROXs 42B b exhibits clear signs of low surface gravity common to young L dwarfs, confirming its extreme youth, cool temperature, and low mass. Overall, it closely resembles the free-floating 4-7 M Jup L-type Taurus member 2MASS J04373705+2331080. The companion to FW Tau AB is more enigmatic. Our optical and near-infrared spectra show strong evidence of outflow activity and disk accretion in the form of line emission from [S II], [O I], Hα, Ca II, [Fe II], Paβ, and H2. The molecular hydrogen emission is spatially resolved as a single lobe that stretches ≈0.''1 (15 AU). Although the extended emission is not kinematically resolved in our data, its morphology resembles shock-excited H2 jets primarily seen in young Class 0 and Class I sources. The near-infrared continuum of FW Tau b is mostly flat and lacks the deep absorption features expected for a cool, late-type object. This may be a result of accretion-induced veiling, especially in light of its strong and sustained Hα emission (EW(Hα) >~ 290 Å). Alternatively, FW Tau b may be a slightly warmer (M5-M8) accreting low-mass star or brown dwarf (0.03-0.15 M ⊙) with an edge-on disk. Regardless, its young evolutionary stage is in stark contrast to its Class III host FW Tau AB, indicating a more rapid disk clearing timescale for the host binary system than for its wide companion. Finally, we present near-infrared spectra of the young (~2-10 Myr) low-mass (12-15 M Jup) companions GSC 6214-210 B and SR 12 C and find they best resemble low-gravity M9.5 and M9 substellar templates. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National

PSYM-WIDE: A Survey for Large-separation Planetary-mass Companions to Late Spectral Type Members of Young Moving Groups

NASA Astrophysics Data System (ADS)

Naud, Marie-Eve; Artigau, Étienne; Doyon, René; Malo, Lison; Gagné, Jonathan; Lafrenière, David; Wolf, Christian; Magnier, Eugene A.

2017-09-01

We present the results of a direct imaging survey for very large separation (>100 au), low-mass companions around 95 nearby young K5-L5 stars and brown dwarfs. They are high-likelihood candidates or confirmed members of the young (≲150 Myr) β Pictoris and AB Doradus moving groups (ABDMG) and the TW Hya, Tucana-Horologium, Columba, Carina, and Argus associations. Images in I\\prime and z\\prime filters were obtained with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South to search for companions down to an apparent magnitude of z\\prime ˜ 22-24 at separations ≳20″ from the targets and in the remainder of the wide 5.‧5 × 5.‧5 GMOS field of view. This allowed us to probe the most distant region where planetary-mass companions could be gravitationally bound to the targets. This region was left largely unstudied by past high-contrast imaging surveys, which probed much closer-in separations. This survey led to the discovery of a planetary-mass (9-13 {M}{Jup}) companion at 2000 au from the M3V star GU Psc, a highly probable member of ABDMG. No other substellar companions were identified. These results allowed us to constrain the frequency of distant planetary-mass companions (5-13 {M}{Jup}) to {0.84}-0.66+6.73% (95% confidence) at semimajor axes between 500 and 5000 au around young K5-L5 stars and brown dwarfs. This is consistent with other studies suggesting that gravitationally bound planetary-mass companions at wide separations from low-mass stars are relatively rare.

Characterizing a New Candidate Benchmark Brown Dwarf Companion in the β Pic Moving Group

NASA Astrophysics Data System (ADS)

Phillips, Caprice; Bowler, Brendan; Liu, Michael C.; Mace, Gregory N.; Sokal, Kimberly R.

2018-01-01

Benchmark brown dwarfs are objects that have at least two measured fundamental quantities such as luminosity and age, and therefore can be used to test substellar atmospheric and evolutionary models. Nearby, young, loose associations such as the β Pic moving group represent some of the best regions in which to identify intermediate-age benchmark brown dwarfs due to their well-constrained ages and metallicities. We present a spectroscopic study of a new companion at the hydrogen-burning limit orbiting a low-mass star at a separation of 9″ (650 AU) in the 23 Myr old β Pic moving group. The medium-resolution near-infrared spectrum of this companion from IRTF/SpeX shows clear signs of low surface gravity and yields an index-based spectral type of M6±1 with a VL-G gravity on the Allers & Liu classification system. Currently, there are four known brown dwarf and giant planet companions in the β Pic moving group: HR 7329 B, PZ Tel B, β Pic b, and 51 Eri b. Depending on its exact age and accretion history, this new object may represent the third brown dwarf companion and fifth substellar companion in this association.

Identifying uncontrolled asthma in young children: clinical scores or objective variables?

PubMed

Leung, T F; Ko, F W S; Sy, H Y; Wong, E; Li, C Y; Yung, E; Hui, D S C; Wong, G W K; Lai, C K W

2009-03-01

Several international asthma guidelines emphasize the importance of assessing asthma control. However, there is limited data on the usefulness of available assessment tools in indicating disease control in young asthmatics. This study investigated the ability of Chinese version of Childhood Asthma Control Test (C-ACT) and other disease-related factors in identifying uncontrolled asthma (UA) in young children. During the same clinic visit, asthma patients 4 to 11 years of age completed C-ACT and underwent exhaled nitric oxide and spirometric measurements. Blinded to these results, the same investigator assigned Disease Severity Score (DSS) and rated asthma control according to Global Initiative for Asthma. The mean (SD) age of 113 recruited patients was 9.1 (2.0) years, and 35% of them had UA. C-ACT, DSS and forced expiratory volume in 1 second (FEV(1)) differed among patients with different control status (p < 0.001 for C-ACT and DSS; p = 0.014 for FEV(1)). Logistic regression confirmed that UA was associated with DSS (p < 0.001), PEF (p = 0.002), C-ACT (p = 0.011), and FEV(1) (p = 0.012). By ROC analysis, C-ACT and DSS were the best predictors for UA (p < 0.001), followed by PEF (p = 0.006) and FEV(1) (p = 0.007). When analyzed by the Classification and Regression Tree (CART) approach, the sequential use of DSS and C-ACT had 77% sensitivity and 84% specificity in identifying UA. C-ACT is better than objective parameters in identifying young Chinese children with UA.

A Pan-STARRS1 Proper-Motion Survey for Young Brown Dwarfs in the Nearest Star-Forming Regions and a Reddening-Free Classification Method for Ultracool Dwarfs

NASA Astrophysics Data System (ADS)

Zhang, Zhoujian; Liu, Michael C.; Best, William M. J.; Magnier, Eugene; Aller, Kimberly

2018-01-01

Young brown dwarfs are of prime importance to investigate the universality of the initial mass function (IMF). Based on photometry and proper motions from the Pan-STARRS1 (PS1) 3π survey, we are conducting the widest and deepest brown dwarf survey in the nearby star-forming regions, Taurus–Auriga (Taurus) and Upper Scorpius (USco). Our work is the first to measure proper motions, a robust proxy of membership, for brown dwarf candidates in Taurus and USco over such a large area and long time baseline (≈ 15 year) with such high precision (≈ 4 mas yr-1). Since extinction complicates spectral classification, we have developed a new approach to quantitatively determine reddening-free spectral types, extinctions, and gravity classifications for mid-M to late-L ultracool dwarfs (≈ 100–5 MJup), using low-resolution near-infrared spectra. So far, our IRTF/SpeX spectroscopic follow-up has increased the substellar and planetary-mass census of Taurus by ≈ 50% and almost doubled the substellar census of USco, constituting the largest single increases of brown dwarfs and free-floating planets found in both regions to date. Most notably, our new discoveries reveal an older (> 10 Myr) low-mass population in Taurus, in accord with recent studies of the higher-mass stellar members. In addition, the mass function appears to differ between the younger and older Taurus populations, possibly due to incompleteness of the older stellar members or different star formation processes. Upon completion, our survey will establish the most complete substellar and planetary-mass census in both Taurus and USco associations, make a significant addition to the low-mass IMF in both regions, and deliver more comprehensive pictures of star formation histories.

Consistency between subjectively and objectively measured hazard perception skills among young male drivers.

PubMed

Ābele, Līva; Haustein, Sonja; Møller, Mette; Martinussen, Laila M

2018-03-01

Young male drivers have lower hazard perception skills (HPS) than older and more experienced drivers and a tendency to overestimate their skills in hazardous situations. Both factors contribute to an over-representation in traffic accidents. Based on a sample of 63 drivers aged 18-24, this study compares the consistency of HPS measured by objective and subjective measures and the link between these measures is the key contribution of the study. Both visible and hidden hazards are included. Objective measures of HPS include responsiveness and eye movements while driving in a driving simulator. Subjective measures of HPS include self-reports derived based on the Hazard Perception Questionnaire (HPQ), Driving Skill Questionnaire (DSQ), and Brief Sensation Seeking Scale (BSSS). Results show that drivers who respond to the hazards on time, as compared to drivers who do not respond, have higher scores on subjective measures of HPS and higher driving skills in the visible but not in the hidden condition. Eye movement analysis confirms the difference and shows that response in time to hazards indicate higher HPS and young drivers are poor at detecting hidden hazards. Drivers with a response in time locate the hazard faster, have more fixations, but dwell less on the hazard. At the same time, those who do not respond have a later first fixation and fewer but longer fixations on the hazard. High sensation seeking drivers respond to visible hazards on time, suggesting that sensation seeking does not affect HPS negatively when the hazard is visible. To enhance the HPS among young drivers, the results of this study suggest that specific hazard perception training is relevant, especially for hazards that require more advanced HPS. Copyright © 2018 Elsevier Ltd. All rights reserved.

Archetype and object: primary deintegration and primary love in analytical play therapy with young children.

PubMed

Peery, J Craig

2002-07-01

Jungian and post-Jungian theory of the development of the child's psyche is reviewed. A discrimination between primary and secondary deintegration is suggested. Post-Freudian theory regarding primary object relations is integrated with the Jungian model. The two approaches can contribute synergistically to inform and advance play therapy with young children. Patients from widely diverse cultural backgrounds use their relationship with the therapist as a helpful person (object), and engage in archetypal material from the collective unconscious, to help them work on and through their unresolved emotional issues.

Mass Accretion Processes in Young Stellar Objects: Role of Intense Flaring Activity

NASA Astrophysics Data System (ADS)

Orlando, Salvatore; Reale, Fabio; Peres, Giovanni; Mignone, Andrea

2014-11-01

According to the magnetospheric accretion scenario, young low-mass stars are surrounded by circumstellar disks which they interact with through accretion of mass. The accretion builds up the star to its final mass and is also believed to power the mass outflows, which may in turn have a signicant role in removing the excess angular momentum from the star-disk system. Although the process of mass accretion is a critical aspect of star formation, some of its mechanisms are still to be fully understood. On the other hand, strong flaring activity is a common feature of young stellar objects (YSOs). In the Sun, such events give rise to perturbations of the interplanetary medium. Similar but more energetic phenomena occur in YSOs and may influence the circumstellar environment. In fact, a recent study has shown that an intense flaring activity close to the disk may strongly perturb the stability of circumstellar disks, thus inducing mass accretion episodes (Orlando et al. 2011). Here we review the main results obtained in the field and the future perspectives.

THE YOUNG STELLAR OBJECT POPULATION IN THE VELA-D MOLECULAR CLOUD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strafella, F.; Maruccia, Y.; Maiolo, B.

2015-01-10

We investigate the young stellar population in the Vela Molecular Ridge, Cloud-D, a star-forming region observed by both the Spitzer/NASA and Herschel/ESA space telescopes. The point-source, band-merged, Spitzer-IRAC catalog complemented with MIPS photometry previously obtained is used to search for candidate young stellar objects (YSOs), also including sources detected in less than four IRAC bands. Bona fide YSOs are selected by using appropriate color-color and color-magnitude criteria aimed at excluding both Galactic and extragalactic contaminants. The derived star formation rate and efficiency are compared with the same quantities characterizing other star-forming clouds. Additional photometric data, spanning from the near-IR tomore » the submillimeter, are used to evaluate both bolometric luminosity and temperature for 33 YSOs located in a region of the cloud observed by both Spitzer and Herschel. The luminosity-temperature diagram suggests that some of these sources are representative of Class 0 objects with bolometric temperatures below 70 K and luminosities of the order of the solar luminosity. Far-IR observations from the Herschel/Hi-GAL key project for a survey of the Galactic plane are also used to obtain a band-merged photometric catalog of Herschel sources intended to independently search for protostars. We find 122 Herschel cores located on the molecular cloud, 30 of which are protostellar and 92 of which are starless. The global protostellar luminosity function is obtained by merging the Spitzer and Herschel protostars. Considering that 10 protostars are found in both the Spitzer and Herschel lists, it follows that in the investigated region we find 53 protostars and that the Spitzer-selected protostars account for approximately two-thirds of the total.« less

The detection of a discrete outflow from the young stellar object GL 490

NASA Technical Reports Server (NTRS)

Mitchell, G. F.; Allen, M.; Beer, R.; Dekany, R.; Huntress, W.

1988-01-01

A high-resolution (0.059/cm) M-band spectrum has been obtained of the embedded young stellar object GL490. The spectrum shows interstellar absorption in the fundamental vibrational band, v = 1-0, of (C-12)O. Two strong and narrow (10 km/s) velocity components are present. One, at the velocity of GL490 (vLSR = -16 km/s), is likely gas in the molecular cloud within which GL490 is embedded. The other component is blueshifted by 13 km/s relative to GL490. An observation of emission from the J = 3-2 transition of HCO(+) using a 20-arcsec beam supports the view that the blueshifted gas is near the central object. The -29-km/s feature is interpreted as a recently ejected shell. It is conjectured that the extended outflows of cold molecular gas seen by millimeter CO emission observations are driven by sporadic outbursts rather than by continuous flows from the central object.

A New Spectroscopic and Interferometric Study of the Young Stellar Object V645 Cyg

NASA Technical Reports Server (NTRS)

Miroshinichenko, A. S.; Hofmann, K.-H.; Schertl, D.; Weigelt, G.; Kraus, S.; Manset, N.; Balega, Y. Y.; Klochkova, V. G.; Rudy, R. J.; Lynch, D. K.;

First Spectroscopic Identification of Massive Young Stellar Objects in the Galactic Center

NASA Technical Reports Server (NTRS)

An, Deokkeun; Ramirez, V.; Sellgren, Kris; Arendt, Richard G.; Boogert, A. C.; Schultheis, Mathias; Stolovy, Susan R.; Cotera, Angela S.; Robitaille, Thomas P.; Smith, Howard A.

2009-01-01

We report the detection of several molecular gas-phase and ice absorption features in three photometrically-selected young stellar object (YSO) candidates in the central 280 pc of the Milky Way. Our spectra, obtained with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, reveal gas-phase absorption from CO2 (15.0 microns), C2H2 (13.7 microns) and HCN (14.0 microns). We attribute this absorption to warm, dense gas in massive YSOs. We also detect strong and broad 15 microns CO2 ice absorption features, with a remarkable double-peaked structure. The prominent long-wavelength peak is due to CH3OH-rich ice grains, and is similar to those found in other known massive YSOs. Our IRS observa.tions demonstra.te the youth of these objects, and provide the first spectroscopic identification of massive YSOs in the Galactic Center.

Young Children's Self-Generated Object Views and Object Recognition

ERIC Educational Resources Information Center

James, Karin H.; Jones, Susan S.; Smith, Linda B.; Swain, Shelley N.

2014-01-01

Two important and related developments in children between 18 and 24 months of age are the rapid expansion of object name vocabularies and the emergence of an ability to recognize objects from sparse representations of their geometric shapes. In the same period, children also begin to show a preference for planar views (i.e., views of objects held…

Young Stellar Objects in Lynds 1641: Disks and Accretion

NASA Astrophysics Data System (ADS)

Fang, Min; Kim, Jinyoung Serena; van Boekel, Roy; Sicilia-Aguilar, Aurora; Henning, Thomas; Flaherty, Kevin

2013-07-01

We investigate the young stellar objects (YSOs) in the Lynds 1641 (L1641) cloud using multi-wavelength data including Spitzer, WISE, 2MASS, and XMM covering 1390 YSOs across a range of evolutionary stages. In addition, we targeted a sub-sample of YSOs for optical spectroscopy with the MMT/Hectospec and the MMT/Hectochelle. We use this data, along with archival photometric data, to derive spectral types, masses, ages and extinction values. We also use the H_alpha and H_beta lines to derive accretion rates. We calculate the disk fraction as N(II)/N(II+III), where N(II) and N(III) are numbers of Class\\ II and Class\\ III sources, respectively, and obtain a disk fraction of 50% in L1641. We find that the disk frequency is almost constant as a function of stellar mass with a slight peak at log(M_*/M_sun) -0.25. The analysis of multi-epoch data indicates that the accretion variability of YSOs cannot explain the two orders of magnitude of scatter for YSOs with similar masses in the M_acc vs. M_* plot. Forty-six new transition disk objects are confirmed in our spectroscopic survey and we find that the fraction of transition disks that are actively accreting is lower than for optically thick disks (40-45% vs. 77-79% respectively). We confirm our previous result that the accreting YSOs with transition disks have a similar median accretion rate to normal optically thick disks. Analyzing the age distributions of various populations, we find that the diskless YSOs are statistically older than the YSOs with optically-thick disks and the transition disk objects have a median age which is intermediate between the two populations.

A Multiplicity Census of Young Stars in Chamaeleon I

NASA Astrophysics Data System (ADS)

Lafrenière, David; Jayawardhana, Ray; Brandeker, Alexis; Ahmic, Mirza; van Kerkwijk, Marten H.

2008-08-01

We present the results of a multiplicity survey of 126 stars spanning ~0.1-3 M⊙ in the ~2 Myr old Chamaeleon I star-forming region, based on adaptive optics imaging with the ESO Very Large Telescope. Our observations have revealed 30 binaries and six triples, of which 19 and four, respectively, are new discoveries. The overall multiplicity fraction we find for Cha I (~30%) is similar to those reported for other dispersed young associations, but significantly higher than seen in denser clusters and the field, for comparable samples. Both the frequency and the maximum separation of Cha I binaries decline with decreasing mass, while the mass ratios approach unity; conversely, tighter pairs are more likely to be equal mass. We confirm that brown dwarf companions to stars are rare, even at young ages at wide separations. Based on follow-up spectroscopy of two low-mass substellar companion candidates, we conclude that both are likely background stars. The overall multiplicity fraction in Cha I is in rough agreement with numerical simulations of cloud collapse and fragmentation, but its observed mass dependence is less steep than predicted. The paucity of higher order multiples, in particular, provides a stringent constraint on the simulations, and seems to indicate a low level of turbulence in the prestellar cores in Cha I.

YSOVAR: MID-INFRARED VARIABILITY OF YOUNG STELLAR OBJECTS AND THEIR DISKS IN THE CLUSTER IRAS 20050+2720

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poppenhaeger, K.; Wolk, S. J.; Hora, J. L.

2015-10-15

We present a time-variability study of young stellar objects (YSOs) in the cluster IRAS 20050+2720, performed at 3.6 and 4.5 μm with the Spitzer Space Telescope; this study is part of the Young Stellar Object VARiability (YSOVAR) project. We have collected light curves for 181 cluster members over 60 days. We find a high variability fraction among embedded cluster members of ca. 70%, whereas young stars without a detectable disk display variability less often (in ca. 50% of the cases) and with lower amplitudes. We detect periodic variability for 33 sources with periods primarily in the range of 2–6 days.more » Practically all embedded periodic sources display additional variability on top of their periodicity. Furthermore, we analyze the slopes of the tracks that our sources span in the color–magnitude diagram (CMD). We find that sources with long variability time scales tend to display CMD slopes that are at least partially influenced by accretion processes, while sources with short variability timescales tend to display extinction-dominated slopes. We find a tentative trend of X-ray detected cluster members to vary on longer timescales than the X-ray undetected members.« less

Memory and representation in young children with Down syndrome: Exploring deferred imitation and object permanence.

PubMed

Rast, Mechthild; Meltzoff, Andrew N

1995-01-01

Deferred imitation and object permanence (OP) were tested in 48 young children with Down syndrome (DS), ranging from 20 to 43 months of age. Deferred imitation and high-level OP (invisible displacements) have long been held to be synchronous developments during sensory-motor "Stage 6" (18-24 months of age in unimpaired children). The results of the current study demonstrate deferred imitation in young children with DS, showing they can learn novel behaviors from observation and retain multiple models in memory. This is the first demonstration of deferred imitation in young children with DS. The average OP level passed in this sample was A-not-B, a task passed at 8-12 months of age in normally developing infants. Analyses showed that individual children who failed high-level OP (invisible displacements) could still perform deferred imitation. This indicates that deferred imitation and OP invisible displacements are not synchronous developments in children with DS. This asynchrony is compatible with new data from unimpaired children suggesting that deferred imitation and high-level OP entail separate and distinctive kinds of memory and representation.

The Optical Gravitational Lensing Experiment. Additional Planetary and Low-Luminosity Object Transits from the OGLE 2001 and 2002 Observational Campaigns

NASA Astrophysics Data System (ADS)

Udalski, A.; Pietrzynski, G.; Szymanski, M.; Kubiak, M.; Zebrun, K.; Soszynski, I.; Szewczyk, O.; Wyrzykowski, L.

2003-06-01

The photometric data collected by OGLE-III during the 2001 and 2002 observational campaigns aiming at detection of planetary or low-luminosity object transits were corrected for small scale systematic effects using the data pipeline by Kruszewski and Semeniuk and searched again for low amplitude transits. Sixteen new objects with small transiting companions, additional to previously found samples, were discovered. Most of them are small amplitude cases which remained undetected in the original data. Several new objects seem to be very promising candidates for systems containing substellar objects: extrasolar planets or brown dwarfs. Those include OGLE-TR-122, OGLE-TR-125, OGLE-TR-130, OGLE-TR-131 and a few others. Those objects are particularly worth spectroscopic follow-up observations for radial velocity measurements and mass determination. With well known photometric orbit only a few RV measurements should allow to confirm their actual status. All photometric data of presented objects are available to the astronomical community from the OGLE Internet archive.

Accretion Signatures on Massive Young Stellar Objects

NASA Astrophysics Data System (ADS)

Navarete, F.; Damineli, A.; Barbosa, C. L.; Blum, R. D.

2015-01-01

We present preliminary results from a survey of molecular H2 (2.12 μm) emission in massive young stellar objects (MYSO) candidates selected from the Red MSX Source survey. We observed 354 MYSO candidates through the H2 S(1) 1-0 transition (2.12 μm) and an adjacent continuum narrow-band filters using the Spartan/SOAR and WIRCam/CFHT cameras. The continuum-subtracted H2 maps were analyzed and extended H2 emission was found in 50% of the sample (178 sources), and 38% of them (66) have polar morphology, suggesting collimated outflows. The polar-like structures are more likely to be driven on radio-quiet sources, indicating that these structures occur during the pre-ultra compact H ii phase. We analyzed the continuum images and found that 54% (191) of the sample displayed extended continuum emission and only ~23% (80) were associated to stellar clusters. The extended continuum emission is correlated to the H2 emission and those sources within stellar clusters does display diffuse H2 emission, which may be due to fluorescent H2 emission. These results support the accretion scenario for massive star formation, since the merging of low-mass stars would not produce jet-like structures. Also, the correlation between jet-like structures and radio-quiet sources indicates that higher inflow rates are required to form massive stars in a typical timescale less than 105 years.

The X-Ray View of Young Stellar Objects

NASA Astrophysics Data System (ADS)

Guedel, Manuel

2007-08-01

X-rays offer ideal access to high-energy phenomena in young, accreting stars. The energy released in magnetic flares has profound effects on the stellar environment. Star-disk magnetic reconnection has been suggested as a possible origin of bipolar jets. Such jets from have been detected at X-ray wavelengths, offering new diagnostics for the energy release and jet shock physics. Finally, eruptive phenomena of FU Ori and EX Lup-type stars have been monitored in X-rays. I will discuss observations and suggest simple models for high-energy eruptive phenomena in young stars.

Effects of Motivation on Young Children's Object Recall and Strategy Use.

PubMed

Nida, Robert E

2015-01-01

The study was designed to examine the effects of motivation on young children's recall for object names and early-emerging mnemonic activities. Seventy-two 4-year-old children were randomly assigned to 1 of 3 instructional conditions: incidental, intentional, or motivational. Each child was shown 10 small toy objects and provided a 90 s study period prior to recall. The children's mnemonic behaviors were videotaped for subsequent coding. The children in the incidental condition were instructed to simply look at the toys while children in the intentional and motivational condition were given explicit instructions to remember. The motivational group was also told that they could keep whichever toys they remembered. A recognition memory task was employed to examine the extent to which the stimuli were encoded during the study period. The children's recall memory did not vary as a function of instructional condition. Children's use of singular versus multiple strategies was calculated, along with a weighted summary score giving most weight to the participant's use of mature mnemonic strategies. Significant differences in strategy use were found, favoring the motivational condition. Significant positive correlations were found between the weighted summary scores and object recall, and the teacher ratings of mastery motivation and object recall. Mastery motivation was found to be unrelated to the strategic summary scores, failing to mediate strategic behaviors. The results suggest that when providing incentives to remember, children apparently engaged in more effortful mnemonic processing in order to remember the items, even though a greater number of items were not recalled.

The Assessment of Elaborated Role-Play in Young Children: Invisible Friends, Personified Objects, and Pretend Identities

ERIC Educational Resources Information Center

Taylor, Marjorie; Sachet, Alison B.; Maring, Bayta L.; Mannering, Anne M.

2013-01-01

Role-play (i.e., pretending in which children imagine and act out the part of another individual) was assessed with child interviews and parent questionnaires about invisible friends, personified objects, and pretend identities in a sample of 208 young children. Children who engaged in role-play did not differ from other children in age or…

A search for embedded young stellar objects in and near the IC 1396 complex

NASA Technical Reports Server (NTRS)

Schwartz, Richard D.; Wilking, Bruce A.; Giulbudagian, Armen L.

1991-01-01

The IRAS data base is used to locate young stellar object candidates in and near the IC 1396 complex located in the Cepheus OB2 association. Co-added survey data are used to identify all sources with a flux density Snu(100) greater than 10 Jy and with Snu(100) greater than Snu(60). The 15 sources located at the positions of globules and dark clouds are further analyzed using the inscan slices to assess the source profiles.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geier, S.; Edelmann, H.; Heber, U.

Substellar objects, like planets and brown dwarfs orbiting stars, are by-products of the star formation process. The evolution of their host stars may have an enormous impact on these small companions. Vice versa a planet might also influence stellar evolution as has recently been argued. Here, we report the discovery of an 8-23 Jupiter-mass substellar object orbiting the hot subdwarf HD 149382 in 2.391 d at a distance of only about five solar radii. Obviously, the companion must have survived engulfment in the red giant envelope. Moreover, the substellar companion has triggered envelope ejection and enabled the sdB star tomore » form. Hot subdwarf stars have been identified as the sources of the unexpected ultraviolet (UV) emission in elliptical galaxies, but the formation of these stars is not fully understood. Being the brightest star of its class, HD 149382 offers the best conditions to detect the substellar companion. Hence, undisclosed substellar companions offer a natural solution for the long-standing formation problem of apparently single hot subdwarf stars. Planets and brown dwarfs may therefore alter the evolution of old stellar populations and may also significantly affect the UV emission of elliptical galaxies.« less

A new spectroscopic and interferometric study of the young stellar object V645 Cygni

NASA Astrophysics Data System (ADS)

Miroshnichenko, A. S.; Hofmann, K.-H.; Schertl, D.; Weigelt, G.; Kraus, S.; Manset, N.; Albert, L.; Balega, Y. Y.; Klochkova, V. G.; Rudy, R. J.; Lynch, D. K.; Mazuk, S.; Venturini, C. C.; Russell, R. W.; Grankin, K. N.; Puetter, R. C.; Perry, R. B.

2009-04-01

Aims: We present the results of high-resolution optical spectroscopy, low-resolution near-IR spectroscopy and near-infrared speckle interferometry of the massive young stellar object candidate V645 Cyg, acquired to refine its fundamental parameters and the properties of its circumstellar envelope. Methods: Speckle interferometry in the H- and K-bands and an optical spectrum in the range 5200-6680 Å with a spectral resolving power of R = 60 000 were obtained at the 6 m telescope of the Russian Academy of Sciences. Another optical spectrum in the range 4300-10 500 Å with R = 79 000 was obtained at the 3.6 m CFHT. Low-resolution spectra in the ranges 0.46-1.4 μm and 1.4-2.5 μm with R ~ 800 and ~700, respectively, were obtained at the 3 m Shane telescope of the Lick Observatory. Results: Using a novel kinematical method based on the non-linear modeling of the neutral hydrogen density profile in the direction toward the object, we propose a distance of D = 4.2 ± 0.2 kpc. We also suggest a revised estimate of the star's effective temperature, T_eff ~ 25 000 K. We resolved the object in both H- and K-bands. Using a two-component ring fit, we derived a compact component size of 14 mas and 12 mas in the H- and K-band, respectively, which correspond to 29 and 26 AU at the revised distance. Analysis of our own and previously published data indicates a ~2 mag decrease in the near-infrared brightness of V645 Cyg at the beginning of the 1980's. At the same time, the cometary nebular condensation N1 appears to fade in this wavelength range with respect to the N0 object, representing the star with a nearly pole-on optically-thick disk and an optically-thin envelope. Conclusions: We conclude that V645 Cyg is a young, massive, main-sequence star, which recently emerged from its cocoon and has already experienced its protostellar accretion stage. The presence of accretion is not necessary to account for the high observed luminosity of (2-6) × 104 M⊙ yr-1. The receding part of

Evidence that the Planetary Candidate CVSO30c is a Background Star from Optical, Seeing-limited Data

NASA Astrophysics Data System (ADS)

Lee, Chien-Hsiu; Chiang, Po-Shih

2018-01-01

We report serendipitous optical imaging of CVSO30c, an exoplanet candidate associated with the pre-main-sequence T Tauri star CVSO30 that resides in the 25 Ori stellar cluster. We perform PSF modeling on our seeing-limited optical image to remove the lights from the host star (CVSO30), allowing us to extract photometry of CVSO30c to be g = 23.2 ± 0.2 (statistic) ± 0.1 (systematic) and r = 21.5 ± 0.1 (statistic) ± 0.1 (systematic) magnitudes, respectively. This is 170 and 80 times too bright in the g and r bands, respectively, if CVSO30c were an L0 substellar object as suggested by previous studies. The optical/infrared colors of CVSO30c are indicative of a stellar, not substellar object, while the object’s color–magnitude diagram position is strikingly inconsistent with expected values for a low-mass member of 25 Ori. Broadband photometry for CVSO30c is instead better fit by contaminants such as a background K3 giant or M subdwarf. Our study demonstrates that optical seeing-limited data can help clarify the nature of candidate wide separation planet-mass companions in young star-forming regions.

Precision Photometric Monitoring of Young Low-mass Stars and Brown Dwarfs: Shedding Light on Rotation, Pulsation, and the Star-disk Connection

NASA Astrophysics Data System (ADS)

Cody, Ann Marie; Hillenbrand, L. A.

2010-01-01

Young star-forming regions are host to a variety of optically variable sources, from accreting and flaring stars to those whose light is modulated by surface spots. In addition, recent theory has suggested that a new type of variability-- pulsation powered by deuterium burning-- may be at work on hour timescales in young brown dwarfs and very low mass stars. Photometric studies of these diverse phenomena are key in probing the underlying physics governing the evolution of few-Myr-old cluster members. High-cadence time series provide insight into not only the stochastic nature of accretion, but also trends in rotation via monitoring of magnetic surface spots. Nevertheless, a complete characterization of variability down to low amplitudes, and particularly amongst very-low-mass (0.01-0.3 M⊙) objects, remains elusive. The lower limit to rotation periods in young clusters is not well established, and mechanisms regulating angular momentum down through the substellar regime are not well understood. To expand the census of variability to very low mass and short timescales, as well as assess the possibility of deuterium-burning pulsation, we have carried out a dedicated monitoring campaign on confirmed low-mass members in several 2-5 Myr clusters. Using meter-class telescopes, our survey achieves sensitivity to periodic variations with photometric amplitudes down to the millimagnitude level on timescales ranging from a fraction of an hour to several weeks. We present results from the 5 Myr Sigma Orionis cluster, including a new compilation of rotation rates and a strong correspondence between variability type and presence of a disk, as indicated by Spitzer/IRAC excesses. In contrast to previous reports of 1-4-hour variability amongst brown dwarfs, we find a dearth of periods under 10 hours. However, we identify a significant positive correlation between rotation period and mass.

2MASS J11151597+1937266: A Young, Dusty, Isolated, Planetary-mass Object with a Potential Wide Stellar Companion

NASA Astrophysics Data System (ADS)

Theissen, Christopher A.; Burgasser, Adam J.; Bardalez Gagliuffi, Daniella C.; Hardegree-Ullman, Kevin K.; Gagné, Jonathan; Schmidt, Sarah J.; West, Andrew A.

2018-01-01

We present 2MASS J11151597+1937266, a recently identified low-surface-gravity L dwarf, classified as an L2γ based on Sloan Digital Sky Survey optical spectroscopy. We confirm this spectral type with near-infrared spectroscopy, which provides further evidence that 2MASS J11151597+1937266 is a low-surface-gravity L dwarf. This object also shows significant excess mid-infrared flux, indicative of circumstellar material; and its strong Hα emission (EWHα = 560 ± 82 Å) is an indicator of enhanced magnetic activity or weak accretion. Comparison of its spectral energy distribution to model photospheres yields an effective temperature of {1724}-38+184 {{K}}. We also provide a revised distance estimate of 37 ± 6 pc using a spectral type–luminosity relationship for low-surface-gravity objects. The three-dimensional galactic velocities and positions of 2MASS J11151597+1937266 do not match any known young association or moving group. Assuming a probable age in the range of 5–45 Myr, the model-dependent estimated mass of this object is between 7 and 21 M Jup, making it a potentially isolated planetary-mass object. We also identify a candidate co-moving, young stellar companion, 2MASS J11131089+2110086.

The Gaseous Disks of Young Stellar Objects

NASA Technical Reports Server (NTRS)

Glassgold, A. E.

2006-01-01

Disks represent a crucial stage in the formation of stars and planets. They are novel astrophysical systems with attributes intermediate between the interstellar medium and stars. Their physical properties are inhomogeneous and are affected by hard stellar radiation and by dynamical evolution. Observing disk structure is difficult because of the small sizes, ranging from as little as 0.05 AU at the inner edge to 100-1000 AU at large radial distances. Nonetheless, substantial progress has been made by observing the radiation emitted by the dust from near infrared to mm wavelengths, i.e., the spectral energy distribution of an unresolved disk. Many fewer results are available for the gas, which is the main mass component of disks over much of their lifetime. The inner disk gas of young stellar objects (henceforth YSOs) have been studied using the near infrared rovibrational transitions of CO and a few other molecules, while the outer regions have been explored with the mm and sub-mm lines of CO and other species. Further progress can be expected in understanding the physical properties of disks from observations with sub-mm arrays like SMA, CARMA and ALMA, with mid infrared measurements using Spitzer, and near infrared spectroscopy with large ground-based telescopes. Intense efforts are also being made to model the observations using complex thermal-chemical models. After a brief review of the existing observations and modeling results, some of the weaknesses of the models will be discussed, including the absence of good laboratory and theoretical calculations for essential microscopic processes.

Memory and representation in young children with Down syndrome: Exploring deferred imitation and object permanence

PubMed Central

RAST, MECHTHILD; MELTZOFF, ANDREW N.

2013-01-01

Deferred imitation and object permanence (OP) were tested in 48 young children with Down syndrome (DS), ranging from 20 to 43 months of age. Deferred imitation and high-level OP (invisible displacements) have long been held to be synchronous developments during sensory-motor “Stage 6” (18–24 months of age in unimpaired children). The results of the current study demonstrate deferred imitation in young children with DS, showing they can learn novel behaviors from observation and retain multiple models in memory. This is the first demonstration of deferred imitation in young children with DS. The average OP level passed in this sample was A-not-B, a task passed at 8–12 months of age in normally developing infants. Analyses showed that individual children who failed high-level OP (invisible displacements) could still perform deferred imitation. This indicates that deferred imitation and OP invisible displacements are not synchronous developments in children with DS. This asynchrony is compatible with new data from unimpaired children suggesting that deferred imitation and high-level OP entail separate and distinctive kinds of memory and representation. PMID:25530676

The Young Substellar Companion ROXs 12 B: Near-infrared Spectrum, System Architecture, and Spin-Orbit Misalignment

NASA Astrophysics Data System (ADS)

Bowler, Brendan P.; Kraus, Adam L.; Bryan, Marta L.; Knutson, Heather A.; Brogi, Matteo; Rizzuto, Aaron C.; Mace, Gregory N.; Vanderburg, Andrew; Liu, Michael C.; Hillenbrand, Lynne A.; Cieza, Lucas A.

2017-10-01

ROXs 12 (2MASS J16262803-2526477) is a young star hosting a directly imaged companion near the deuterium-burning limit. We present a suite of spectroscopic, imaging, and time-series observations to characterize the physical and environmental properties of this system. Moderate-resolution near-infrared spectroscopy of ROXs 12 B from Gemini-North/NIFS and Keck/OSIRIS reveals signatures of low surface gravity including weak alkali absorption lines and a triangular H-band pseudocontinuum shape. No signs of Paβ emission are evident. As a population, however, we find that about half (46% ± 14%) of young (≲15 Myr) companions with masses ≲20 M Jup possess actively accreting subdisks detected via Paβ line emission, which represents a lower limit on the prevalence of circumplanetary disks in general, as some are expected to be in a quiescent phase of accretion. The bolometric luminosity of the companion and age of the host star ({6}-2+4 Myr) imply a mass of 17.5 ± 1.5 M Jup for ROXs 12 B based on hot-start evolutionary models. We identify a wide (5100 au) tertiary companion to this system, 2MASS J16262774-2527247, that is heavily accreting and exhibits stochastic variability in its K2 light curve. By combining v sin I * measurements with rotation periods from K2, we constrain the line-of-sight inclinations of ROXs 12 A and 2MASS J16262774-2527247 and find that they are misaligned by {{60}-11+7}^\\circ . In addition, the orbital axis of ROXs 12 B is likely misaligned from the spin axis of its host star, ROXs 12 A, suggesting that ROXs 12 B formed akin to fragmenting binary stars or in an equatorial disk that was torqued by the wide stellar tertiary. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support

How Young Children and Chimpanzees ("Pan Troglodytes") Perceive Objects in a 2D Display: Putting an Assumption to the Test

ERIC Educational Resources Information Center

Leighty, Katherine A.; Menzel, Charles R.; Fragaszy, Dorothy M.

2008-01-01

Object recognition research is typically conducted using 2D stimuli in lieu of 3D objects. This study investigated the amount and complexity of knowledge gained from 2D stimuli in adult chimpanzees ("Pan troglodytes") and young children (aged 3 and 4 years) using a titrated series of cross-dimensional search tasks. Results indicate that 3-year-old…

WISE Identified Young Stellar Objects In BRC 38

NASA Astrophysics Data System (ADS)

Gibbs, John; Rebull, L. M.; Laurence, W.; Marshall, R.; Murphy, M.; Orr, L.; Whitworth, C.; Burton, A.; Corris, T.; Goodey, S.; McGinnis, S.; Laurence, C.; Aschman, O.; Kikuchi, R.; Prather, J.; Whitley, L.; Billings, C.; Mader, C.

2014-01-01

Bright rimmed clouds (BRCs) are dense clumps of gas and dust within HII regions at the edges of molecular clouds; while the BRCs themselves are dark, their rims are optically bright from illumination by nearby O or B stars. Many BRCs show evidence of active star formation possibly triggered by the ionizing radiation from the nearby O or B stars. The large molecular cloud IC1396 is home to eleven BRCs thought to be driven by the O6.5V star HD206267. BRC 38 is located in the north of IC1396, at 21:40:42 +58:16:13. The immediate ~5'x5' region around BRC 38 has been extensively studied in many wavelengths from X-rays to infrared (IR), identifying ~100 young stellar objects (YSOs). We used data from the Wide-field Infrared Survey Explorer (WISE) to expand the search for YSOs to a 20 arcminute radius from the center of BRC 38. Starting with approximately 7000 sources identified in the WISE catalog, we used an updated version of the IR color selection scheme developed by Koenig et al. (2012) to identify ~40 objects having IR colors consistent with those of YSOs; some overlapping with the literature YSO candidates. Combining confirmed and candidate YSOs from literature with those we identified by color selection, we find 115 unique objects of interest. For each of these sources, we analyzed (a) the WISE, 2MASS, and Spitzer images to determine if they were point-like sources; (b) their IR colors to determine if they exhibited a clear IR excess; and (c) their spectral energy distributions (SEDs) to determine if they had an SED shape consistent with their identification as YSO candidates. Our work adds several new YSO candidates to the list of YSOs in and near BRC 38 and newly identifies IR excesses for many of the previously identified YSOs in the region. We looked for evidence of triggered star formation in BRC 38, but are limited in our conclusions by small-number statistics. Support is provided for this work by the NASA/IPAC Teacher Archive Research Program (NITARP

Contrasting preschoolers' verbal reasoning in an object-individuation task with young infants' preverbal feats.

PubMed

Krist, Horst; Karl, Karoline; Krüger, Markus

2016-12-01

Young infants infer a second object if shown an object apparently moving on a discontinuous path (Aguiar & Baillargeon, 2002; Spelke, Kestenbaum, Simons, & Wein, 1995). In three experiments, we examined whether children aged 3-6 years and adults would do the same in their verbal explanations of an apparent continuity violation. Presenting participants with video clips (Exp. 1 and 3) as well as live events (Exp. 2) of a toy locomotive apparently passing through a tunnel without appearing in a large opening in the middle, we found virtually no evidence for generations of two-object explanations of the critical test event in preschoolers. Some of the younger children even denied a continuity violation at first. When participants were familiarized to two identical objects instead of just one, they were more likely to realize that a second object was involved in the test events but, unlike adults (Exp. 3), most children nonetheless adhered to a one-object interpretation. Analyzing 3- and 5-year-old children's and adults' eye movements (Exp. 3), we found that children's difficulties to infer a second object from an apparent continuity violation were not caused by inappropriate looking strategies. We conclude that preschoolers' physical reasoning about the numerical identity of objects is not continuous with the preverbal reasoning of infants. Rather than being exclusively constrained by the output of basic object-individuation processes, as in infants, it is also strongly influenced, in a top-down manner, by prior beliefs. Copyright © 2016 Elsevier B.V. All rights reserved.

SPITZER OBSERVATIONS OF LONG-TERM INFRARED VARIABILITY AMONG YOUNG STELLAR OBJECTS IN CHAMAELEON I

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flaherty, Kevin M.; Herbst, William; DeMarchi, Lindsay

Infrared variability is common among young stellar objects, with surveys finding daily to weekly fluctuations of a few tenths of a magnitude. Space-based observations can produce highly sampled infrared light curves, but are often limited to total baselines of about 1 month due to the orientation of the spacecraft. Here we present observations of the Chameleon I cluster, whose low declination makes it observable by the Spitzer Space Telescope over a 200-day period. We observe 30 young stellar objects with a daily cadence to better sample variability on timescales of months. We find that such variability is common, occurring inmore » ∼80% of the detected cluster members. The change in [3.6]–[4.5] color over 200 days for many of the sources falls between that expected for extinction and fluctuations in disk emission. With our high cadence and long baseline we can derive power spectral density curves covering two orders of magnitude in frequency and find significant power at low frequencies, up to the boundaries of our 200-day survey. Such long timescales are difficult to explain with variations driven by the interaction between the disk and stellar magnetic field, which has a dynamical timescale of days to weeks. The most likely explanation is either structural or temperature fluctuations spread throughout the inner ∼0.5 au of the disk, suggesting that the intrinsic dust structure is highly dynamic.« less

Mouthing of Soil Contaminated Objects is Associated with Environmental Enteropathy in Young Children.

PubMed

Morita, Tomohiko; Perin, Jamie; Oldja, Lauren; Biswas, Shwapon; Sack, R Bradley; Ahmed, Shahnawaz; Haque, Rashidul; Bhuiyan, Nurul Amin; Parvin, Tahmina; Bhuyian, Sazzadul Islam; Akter, Mahmuda; Talukder, Kaisar A; Shahnaij, Mohammad; Faruque, Abu G; George, Christine Marie

2017-06-01

To characterise childhood mouthing behaviours and to investigate the association between object-to-mouth and food-to-mouth contacts, diarrhoea prevalence and environmental enteropathy. A prospective cohort study was conducted of 216 children ≤30 months of age in rural Bangladesh. Mouthing contacts with soil and food and objects with visible soil were assessed by 5-h structured observation. Stool was analysed for four faecal markers of intestinal inflammation: alpha-1-antitrypsin, myeloperoxidase, neopterin and calprotectin. Overall 82% of children were observed mouthing soil, objects with visible soil, or food with visible soil during the structured observation period. Sixty two percent of children were observed mouthing objects with visible soil, 63% were observed mouthing food with visible soil, and 18% were observed mouthing soil only. Children observed mouthing objects with visible soil had significantly elevated faecal calprotectin concentrations (206.81 μg/g, 95% confidence interval [CI]: 6.27, 407.36). There was also a marginally significant association between Escherichia coli counts in soil from a child's play space and the prevalence rate of diarrhoea (diarrhoea prevalence ratio: 2.03, 95% CI 0.97, 4.25). These findings provide further evidence to support the hypothesis that childhood mouthing behaviour in environments with faecal contamination can lead to environmental enteropathy in susceptible paediatric populations. Furthermore, these findings suggest that young children mouthing objects with soil, which occurred more frequently than soil directly (60% vs. 18%), was an important exposure route to faecal pathogens and a risk factor for environmental enteropathy. © 2017 John Wiley & Sons Ltd.

Ionised Jets Associated With Massive Young Stellar Objects

NASA Astrophysics Data System (ADS)

Purser, Simon John Derek

2017-09-01

This thesis focuses on the phenomena of ionised jets associated with massive young stellar objects. Firstly a study was conducted with the aim to establish a statistical sample of such objects. Radio observations towards a sample of 49 MYSOs resulted in the detection of 28 objects classified as ionised jets. The jets’ radio luminosities scaled with their MYSOs’ bolometric luminosities in the same way as for low-mass examples. This infers that the jet launching and collimation mechanisms of high-mass jets are very similar to that in their low-mass counterparts and they are ejected for the last ≤65000 yr of the MYSO phase. Interestingly non-thermal emission was regularly detected towards spatially distinct radio lobes (associated with ˜50% of the jets), suggesting the presence of synchrotron emission and therefore, magnetic fields. With an average spectral index of ¯α=‑0. 55 (indicative of the 1st order Fermi acceleration mechanism) it is concluded these lobes are the result of shocks in the jets’ stream. My second science chapter is a study of radio variability, precession and proper motions towards a subset of objects from the first chapter. Over a two year time period, no significant variability and only one example of proper motion (1800±600 km s‑1) was detected. Precession was found to be commonplace however and if it arises as the result of binary interactions, we infer orbital radii between 30 and 1800 au for the binary companions. Lastly, high-resolution, VLA observations at C and Q-bands were analysed to extend the known sample of MYSOs harbouring ionised jets into the northern hemisphere. Only 3 radio sources were detected possessing jet-like characteristics towards the work’s sub-sample of 8 IRDCs containing 44 mm-cores (in our field of view), highlighting the radio-quiet (≳30μJy) nature of this early phase in massive star formation. Towards the RMS survey derived sample of 48 MYSOs, a total of 38 radio sources with jet

CO bandhead emission of massive young stellar objects: determining disc properties

NASA Astrophysics Data System (ADS)

Ilee, J. D.; Wheelwright, H. E.; Oudmaijer, R. D.; de Wit, W. J.; Maud, L. T.; Hoare, M. G.; Lumsden, S. L.; Moore, T. J. T.; Urquhart, J. S.; Mottram, J. C.

2013-03-01

Massive stars play an important role in many areas of astrophysics, but numerous details regarding their formation remain unclear. In this paper we present and analyse high-resolution (R ˜ 30 000) near-infrared 2.3 μm spectra of 20 massive young stellar objects (MYSOs) from the Red MSX Source (RMS) data base, in the largest such study of CO first overtone bandhead emission to date. We fit the emission under the assumption it originates from a circumstellar disc in Keplerian rotation. We explore three approaches to modelling the physical conditions within the disc - a disc heated mainly via irradiation from the central star, a disc heated mainly via viscosity, and a disc in which the temperature and density are described analytically. We find that the models described by heating mechanisms are inappropriate because they do not provide good fits to the CO emission spectra. We therefore restrict our analysis to the analytic model, and obtain good fits to all objects that possess sufficiently strong CO emission, suggesting circumstellar discs are the source of this emission. On average, the temperature and density structure of the discs correspond to geometrically thin discs, spread across a wide range of inclinations. Essentially all the discs are located within the dust sublimation radius, providing strong evidence that the CO emission originates close to the central protostar, on astronomical unit scales. In addition, we show that the objects in our sample appear no different to the general population of MYSOs in the RMS data base, based on their near- and mid-infrared colours. The combination of observations of a large sample of MYSOs with CO bandhead emission and our detailed modelling provide compelling evidence of the presence of small-scale gaseous discs around such objects, supporting the scenario in which massive stars form via disc accretion.

A sudden brightness decrease of the young pre-MS object GM Cep

NASA Astrophysics Data System (ADS)

Munari, U.; Castellani, F.; Giannini, T.; Antoniucci, S.; Lorenzetti, D.

2017-11-01

In the framework of our EXor monitoring programme dubbed EXORCISM (EXOR OptiCal and Infrared Systematic Monitoring - Antoniucci et al. 2013 PPVI, Lorenzetti et al. 2007 ApJ 665, 1182; Lorenzetti et al. 2009 ApJ 693, 1056), we observed a new fading of the optical brightness of the Young Stellar Object (YSO) GM Cep (d=870 pc). This is a well studied variable (Semkov & Peneva 2012 APSS,338,95; Ibryamov et al. 2015 PASA,32,11; Xiao, Kroll, & Henden 2010 AJ, 139, 1527; Sicilia-Aguilar et al. 2008 ApJ,673,382-3) whose light-curve is dominated by recurrent brightness dims, interpreted as non-periodical eclipse events due to orbiting dust structures that move along the line of sight (UXor-type variability - Grinin 1988).

IRAS observations of young stellar objects in the Corona Australis dark cloud

NASA Technical Reports Server (NTRS)

Wilking, Bruce A.; Greene, Thomas P.; Lada, Charles J.; Meyer, Michael R.; Young, Erick T.

1992-01-01

The young stellar object (YSO) population associated with the dark cloud complex in Corona Australis is studied by synthesizing IRAS data with newly obtained near-IR and mid-IR photometry and previously published optical/IR data. Twenty-four YSOs in the Cr A complex are identified. The observed range of spectral energy distribution shapes and bolometric luminosities are consistent with those observed in other dark clouds. The duration and efficiency of star formation are found to be similar to the Rho Ophiuchi IR cluster. The low number of YSOs compared to other dark clouds is understood by a reevaluation of the molecular mass of the R Cr A cloud which shows it to be much less massive than previously assumed.

Planets around Low-mass Stars (PALMS). I. A Substellar Companion to the Young M Dwarf 1RXS J235133.3+312720

NASA Astrophysics Data System (ADS)

Bowler, Brendan P.; Liu, Michael C.; Shkolnik, Evgenya L.; Dupuy, Trent J.; Cieza, Lucas A.; Kraus, Adam L.; Tamura, Motohide

2012-07-01

We report the discovery of a brown dwarf companion to the young M dwarf 1RXS J235133.3+312720 as part of a high contrast imaging search for planets around nearby young low-mass stars with Keck-II/NIRC2 and Subaru/HiCIAO. The 2farcs4 (~120 AU) pair is confirmed to be comoving from two epochs of high-resolution imaging. Follow-up low- and moderate-resolution near-infrared spectroscopy of 1RXS J2351+3127 B with IRTF/SpeX and Keck-II/OSIRIS reveals a spectral type of L0+2 -1. The M2 primary star 1RXS J2351+3127 A exhibits X-ray and UV activity levels comparable to young moving group members with ages of ~10-100 Myr. UVW kinematics based the measured radial velocity of the primary and the system's photometric distance (50 ± 10 pc) indicate it is likely a member of the ~50-150 Myr AB Dor moving group. The near-infrared spectrum of 1RXS J2351+3127 B does not exhibit obvious signs of youth, but its H-band morphology shows subtle hints of intermediate surface gravity. The spectrum is also an excellent match to the ~200 Myr M9 brown dwarf LP 944-20. Assuming an age of 50-150 Myr, evolutionary models imply a mass of 32 ± 6 M Jup for the companion, making 1RXS J2351+3127 B the second lowest-mass member of the AB Dor moving group after the L4 companion CD-35 2722 B and one of the few benchmark brown dwarfs known at young ages. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

A MODEL FOR (QUASI-)PERIODIC MULTIWAVELENGTH PHOTOMETRIC VARIABILITY IN YOUNG STELLAR OBJECTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kesseli, Aurora Y.; Petkova, Maya A.; Wood, Kenneth

We present radiation transfer models of rotating young stellar objects (YSOs) with hot spots in their atmospheres, inner disk warps, and other three-dimensional effects in the nearby circumstellar environment. Our models are based on the geometry expected from magneto-accretion theory, where material moving inward in the disk flows along magnetic field lines to the star and creates stellar hot spots upon impact. Due to rotation of the star and magnetosphere, the disk is variably illuminated. We compare our model light curves to data from the Spitzer YSOVAR project to determine if these processes can explain the variability observed at opticalmore » and mid-infrared wavelengths in young stars. We focus on those variables exhibiting “dipper” behavior that may be periodic, quasi-periodic, or aperiodic. We find that the stellar hot-spot size and temperature affects the optical and near-infrared light curves, while the shape and vertical extent of the inner disk warp affects the mid-IR light curve variations. Clumpy disk distributions with non-uniform fractal density structure produce more stochastic light curves. We conclude that magneto-accretion theory is consistent with certain aspects of the multiwavelength photometric variability exhibited by low-mass YSOs. More detailed modeling of individual sources can be used to better determine the stellar hot-spot and inner disk geometries of particular sources.« less

Observations of Young Stellar Objects with Infrared Interferometry: Recent Results from PTI, KI and IOTA

NASA Astrophysics Data System (ADS)

Akeson, Rachel

Young stellar objects have been one of the favorite targets of infrared interferometers for many years. In this contribution I will briefly review some of the first results and their contributions to the field and then describe some of the recent results from the Keck Interferometer (KI), the Palomar Testbed Interferometer (PTI) and the Infrared-Optical Telescope Array (IOTA). This conference also saw many exciting new results from the VLTI at both near and mid-infrared wavelengths that are covered by other contributions.

Young Infants' Expectations about Hidden Objects

ERIC Educational Resources Information Center

Ruffman, Ted; Slade, Lance; Redman, Jessica

2005-01-01

Infants aged 3-5 months (mean of approximately 4 months) were given a novel anticipatory looking task to test object permanence understanding. They were trained to expect an experimenter to retrieve an object from behind a transparent screen upon hearing a cue (''Doors up, here comes the hand''). The experimenter then hid the object behind one of…

The influence of familiar characters and other appealing images on young children's preference for low-quality objects.

PubMed

Danovitch, Judith H; Mills, Candice M

2017-09-01

This study examines the factors underlying young children's preference for products bearing a familiar character's image. Three-year-olds (N = 92) chose between low-quality objects with images on or near the objects and high-quality objects without images. Children showed stronger preferences for damaged objects bearing images of a preferred familiar character than for objects bearing images of a preferred colour star, and they showed weak preferences for damaged objects with the character near, but not on, the object. The results suggest that children's preference for low-quality products bearing character images is driven by prior exposure to characters, and not only by the act of identifying a favourite. Statement of contribution What is already known on this subject? Children are exposed to characters in the media and on products such as clothing and school supplies. Products featuring familiar characters appeal to preschool children, even if they are of low quality. What does this study add? Three-year-olds prefer damaged objects with an image of a favourite character over plain undamaged objects. Children's preference is not solely a function of having identified a favourite image or of attentional cues. © 2017 The British Psychological Society.

A WISE CENSUS OF YOUNG STELLAR OBJECTS IN CANIS MAJOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, William J.; Padgett, Deborah L.; Sewiło, Marta

With the Wide-field Infrared Survey Explorer (WISE), we searched for young stellar objects (YSOs) in a 100 deg{sup 2} region centered on the lightly studied Canis Major star-forming region. Applying stringent magnitude cuts to exclude the majority of extragalactic contaminants, we find 144 Class I candidates and 335 Class II candidates. The sensitivity to Class II candidates is limited by their faintness at the distance to Canis Major (assumed as 1000 pc). More than half the candidates (53%) are found in 16 groups of more than four members, including four groups with more than 25 members each. The ratio ofmore » Class II to Class I objects, N {sub II}/ N {sub I}, varies from 0.4 to 8.3 in just the largest four groups. We compare our results to those obtainable with combined Two Micron All Sky Survey and post-cryogenic Spitzer Space Telescope data; the latter approach recovers missing Class II sources. Via a comparison to protostars characterized with the Herschel Space Observatory , we propose new WISE color criteria for flat-spectrum and Class 0 protostars, finding 80 and 7 of these, respectively. The distribution of YSOs in CMa OB1 is consistent with supernova-induced star formation, although the diverse N {sub II}/ N {sub I} ratios are unexpected if this parameter traces age and the YSOs are due to the same supernova. Less massive clouds feature larger N {sub II}/ N {sub I} ratios, suggesting that initial conditions play a role in determining this quantity.« less

Growth of a Massive Young Stellar Object Fed by a Gas Flow from a Companion Gas Clump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xi; Shen, Zhiqiang; Ren, Zhiyuan

We present a Submillimeter Array (SMA) observation toward the young massive double-core system G350.69-0.49. This system consists of a northeast (NE) diffuse gas bubble and a southwest (SW) massive young stellar object (MYSO), both clearly seen in the Spitzer images. The SMA observations reveal a gas flow between the NE bubble and the SW MYSO in a broad velocity range from 5 to 30 km s{sup −1} with respect to the system velocity. The gas flow is well confined within the interval between the two objects and traces a significant mass transfer from the NE gas bubble to the SWmore » massive core. The transfer flow can supply the material accreted onto the SW MYSO at a rate of 4.2×10{sup −4} M{sub ⊙} yr{sup −1}. The whole system therefore suggests a mode for the mass growth in the MYSO from a gas transfer flow launched from its companion gas clump, despite the driving mechanism of the transfer flow not being fully determined from the current data.« less

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

NASA Technical Reports Server (NTRS)

Liu, Wilson M.; Padgett, Deborah L.; Terebey, Susan; Angione, John; Rebull, Luisa M.; McCollum, Bruce; Fajardo-Acosta, Sergio; Leisawitz, David

2015-01-01

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, 4.6, 12, and 22 microns, 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.

A Pan-Carina Young Stellar Object Catalog: Intermediate-mass Young Stellar Objects in the Carina Nebula Identified Via Mid-infrared Excess Emission

NASA Astrophysics Data System (ADS)

Povich, Matthew S.; Smith, Nathan; Majewski, Steven R.; Getman, Konstantin V.; Townsley, Leisa K.; Babler, Brian L.; Broos, Patrick S.; Indebetouw, Rémy; Meade, Marilyn R.; Robitaille, Thomas P.; Stassun, Keivan G.; Whitney, Barbara A.; Yonekura, Yoshinori; Fukui, Yasuo

2011-05-01

We present a catalog of 1439 young stellar objects (YSOs) spanning the 1.42 deg2 field surveyed by the Chandra Carina Complex Project (CCCP), which includes the major ionizing clusters and the most active sites of ongoing star formation within the Great Nebula in Carina. Candidate YSOs were identified via infrared (IR) excess emission from dusty circumstellar disks and envelopes, using data from the Spitzer Space Telescope (the Vela-Carina survey) and the Two-Micron All Sky Survey. We model the 1-24 μm IR spectral energy distributions of the YSOs to constrain physical properties. Our Pan-Carina YSO Catalog (PCYC) is dominated by intermediate-mass (2 M sun < m <~ 10 M sun) objects with disks, including Herbig Ae/Be stars and their less evolved progenitors. The PCYC provides a valuable complementary data set to the CCCP X-ray source catalogs, identifying 1029 YSOs in Carina with no X-ray detection. We also catalog 410 YSOs with X-ray counterparts, including 62 candidate protostars. Candidate protostars with X-ray detections tend to be more evolved than those without. In most cases, X-ray emission apparently originating from intermediate-mass, disk-dominated YSOs is consistent with the presence of low-mass companions, but we also find that X-ray emission correlates with cooler stellar photospheres and higher disk masses. We suggest that intermediate-mass YSOs produce X-rays during their early pre-main-sequence evolution, perhaps driven by magnetic dynamo activity during the convective atmosphere phase, but this emission dies off as the stars approach the main sequence. Extrapolating over the stellar initial mass function scaled to the PCYC population, we predict a total population of >2 × 104 YSOs and a present-day star formation rate (SFR) of >0.008 M sun yr-1. The global SFR in the Carina Nebula, averaged over the past ~5 Myr, has been approximately constant.

Predicting changes in clinical status of young asthmatics: clinical scores or objective parameters?

PubMed

Leung, Ting F; Ko, Fanny W S; Wong, Gary W K; Li, Chung Y; Yung, Edmund; Hui, David S C; Lai, Christopher K W

2009-05-01

Preventing asthma exacerbation is an important goal of asthma management. The existing clinical tools are not good in predicting asthma exacerbations in young children. Childhood Asthma Control Test (C-ACT) was recently published to be a simple tool for assessing disease control in young children. This study investigated C-ACT and other disease-related factors for indicating longitudinal changes in asthma status and predicting asthma exacerbations. During the same clinic visit, asthma patients aged 4-11 years completed the Chinese version of C-ACT and underwent exhaled nitric oxide and spirometric measurements. Blinded to these results, the same investigator assigned Disease Severity Score (DSS) and rated asthma control according to Global Initiative for Asthma. Asthma exacerbations during the next 6 months were recorded. Ninety-seven patients were recruited, with their mean (standard deviation [SD]) age being 9.2 (2.0) years. Thirty-six (37.1%) patients had uncontrolled asthma at baseline. C-ACT, DSS, and FEV(1) differed among patients with different control status (P < 0.001 for C-ACT and DSS; P = 0.028 for FEV(1)). Thirty-two patients had asthma exacerbations during the 6-month follow-up. Changes in patients' C-ACT scores correlated with changes in asthma control status, DSS, and FEV(1) (P = 0.019, 0.034, and 0.020, respectively). C-ACT score was lower among patients with asthma exacerbations (mean [SD]: 22.9 [4.2] vs. 24.5 [2.1]; P = 0.015). Logistic regression confirmed that the occurrence of asthma exacerbations was associated only with baseline C-ACT (B = -0.203, P = 0.042). In conclusion, C-ACT is better than DSS and objective parameters in reflecting changes in asthma status and predicting asthma exacerbations in young children. (c) 2009 Wiley-Liss, Inc.

Measuring the Outflows from Massive Young Stellar Objects in the Large Magellanic Cloud (LMC)

NASA Astrophysics Data System (ADS)

Meixner, Margaret

2015-10-01

The formation of massive stars has been difficult to study because they evolve quickly and evolutionary phases are short-lived. Using the GREAT instrument, we propose to measure the molecular gas outflows in 4 massive young stellar objects (YSOs) that we discovered in the Large Magellanic Cloud (LMC) with our Herschel and Spitzer surveys. We have in hand ALMA observations of the CO J=2-1 for all 4 targets. Three of these YSOs mark active young star formation sites in N159W that is the most intense and concentrated molecular cloud in the LMC. The fourth YSO, located in N79, is the most massive/luminous YSO in the LMC. One of the N159W YSOs has been detected with an outflow in the CO J=2-1 line. We will observe the CO J=11-10 line in these 4 YSOs because the shock excited outflows are very bright in this line and it can be used to quantify the mass loss rate. We will also map the most massive YSO in the [CII] 158 micron line to probe the physical conditions of the region.

A 1.3 mm SMA survey of 29 variable young stellar objects

NASA Astrophysics Data System (ADS)

Liu, Hauyu Baobab; Dunham, Michael M.; Pascucci, Ilaria; Bourke, Tyler L.; Hirano, Naomi; Longmore, Steven; Andrews, Sean; Carrasco-González, Carlos; Forbrich, Jan; Galván-Madrid, Roberto; Girart, Josep M.; Green, Joel D.; Juárez, Carmen; Kóspál, Ágnes; Manara, Carlo F.; Palau, Aina; Takami, Michihiro; Testi, Leonardo; Vorobyov, Eduard I.

2018-04-01

Context. Young stellar objects (YSOs) may undergo periods of active accretion (outbursts), during which the protostellar accretion rate is temporarily enhanced by a few orders of magnitude. Whether or not these accretion outburst YSOs possess similar dust and gas reservoirs to each other, and whether or not their dust and gas reservoirs are similar as quiescent YSOs, are issues yet to be clarified. Aims: The aim of this work is to characterize the millimeter thermal dust emission properties of a statistically significant sample of long and short duration accretion outburst YSOs (i.e., FUors and EXors) and the spectroscopically identified candidates of accretion outbursting YSOs (i.e., FUor-like objects). Methods: We have carried out extensive Submillimeter Array (SMA) observations mostly at 225 GHz (1.33 mm) and 272 GHz (1.10 mm), from 2008 to 2017. We covered accretion outburst YSOs located at <1 kpc distances from the solar system. Results: We analyze all the existing SMA data of such objects, both published and unpublished, in a coherent way to present a millimeter interferometric database of 29 objects. We obtained 21 detections at >3σ significance. Detected sources except for the two cases of V883 Ori and NGC 2071 MM3 were observed with 1″ angular resolution. Overall our observed targets show a systematically higher millimeter luminosity distribution than those of the M* > 0.3 M⊙ Class II YSOs in the nearby (≲400 pc) low-mass star-forming molecular clouds (e.g., Taurus, Lupus, Upp Scorpio, and Chameleon I). In addition, at 1 mm our observed confirmed binaries or triple-system sources are systematically fainter than the rest of the sources even though their 1 mm fluxes are broadly distributed. We may have detected 30-60% millimeter flux variability from V2494 Cyg and V2495 Cyg, from the observations separated by approximately one year.

The RMS survey: near-IR spectroscopy of massive young stellar objects

NASA Astrophysics Data System (ADS)

Cooper, H. D. B.; Lumsden, S. L.; Oudmaijer, R. D.; Hoare, M. G.; Clarke, A. J.; Urquhart, J. S.; Mottram, J. C.; Moore, T. J. T.; Davies, B.

2013-04-01

Near-infrared H- and K-band spectra are presented for 247 objects, selected from the Red MSX Source (RMS) survey as potential young stellar objects (YSOs). 195 (˜80 per cent) of the targets are YSOs, of which 131 are massive YSOs (LBOL > 5 × 103 L⊙, M > 8 M⊙). This is the largest spectroscopic study of massive YSOs to date, providing a valuable resource for the study of massive star formation. In this paper, we present our exploratory analysis of the data. The YSOs observed have a wide range of embeddedness (2.7 < AV < 114), demonstrating that this study covers minimally obscured objects right through to very red, dusty sources. Almost all YSOs show some evidence for emission lines, though there is a wide variety of observed properties. The most commonly detected lines are Brγ, H2, fluorescent Fe II, CO bandhead, [Fe II] and He I 2-1 1S-1P, in order of frequency of occurrence. In total, ˜40 per cent of the YSOs display either fluorescent Fe II 1.6878 μm or CO bandhead emission (or both), indicative of a circumstellar disc; however, no correlation of the strength of these lines with bolometric luminosity was found. We also find that ˜60 per cent of the sources exhibit [Fe II] or H2 emission, indicating the presence of an outflow. Three quarters of all sources have Brγ in emission. A good correlation with bolometric luminosity was observed for both the Brγ and H2 emission line strengths, covering 1 < LBOL < 3.5 × 105 L⊙. This suggests that the emission mechanism for these lines is the same for low-, intermediate- and high-mass YSOs, i.e. high-mass YSOs appear to resemble scaled-up versions of low-mass YSOs.

Variable stars around selected open clusters in the VVV area: Young Stellar Objects

NASA Astrophysics Data System (ADS)

Medina, Nicolas; Borissova, Jura; Bayo, Amelia; Kurtev, Radostin; Lucas, Philip

2017-09-01

Time-varying phenomena are one of the most substantial sources of astrophysical information, and led to many fundamental discoveries in modern astronomy. We have developed an automated tool to search and analyze variable sources in the near infrared Ks band, using the data from the Vista Variables in the Vía Láctea (VVV) ESO Public Survey ([5, 8]). One of our main goals is to investigate the Young Stellar Objects (YSOs) in the Galactic star forming regions, looking for: •Variability. •New pre-main sequence star clusters. Here we present the newly discovered YSOs within some selected stellar clusters in our Galaxy.

The MUCHFUSS photometric campaign

NASA Astrophysics Data System (ADS)

Schaffenroth, V.; Geier, S.; Heber, U.; Gerber, R.; Schneider, D.; Ziegerer, E.; Cordes, O.

2018-06-01

Hot subdwarfs (sdO/Bs) are the helium-burning cores of red giants, which have lost almost all of their hydrogen envelope. This mass loss is often triggered by common envelope interactions with close stellar or even substellar companions. Cool companions like late-type stars or brown dwarfs are detectable via characteristic light-curve variations like reflection effects and often also eclipses. To search for such objects, we obtained multi-band light curves of 26 close sdO/B binary candidates from the MUCHFUSS project with the BUSCA instrument. We discovered a new eclipsing reflection effect system (P = 0.168938 d) with a low-mass M dwarf companion (0.116 M⊙). Three more reflection effect binaries found in the course of the campaign have already been published; two of them are eclipsing systems, and in one system only showing the reflection effect but no eclipses, the sdB primary is found to be pulsating. Amongst the targets without reflection effect a new long-period sdB pulsator was discovered and irregular light variations were found in two sdO stars. The found light variations allowed us to constrain the fraction of reflection effect binaries and the substellar companion fraction around sdB stars. The minimum fraction of reflection effect systems amongst the close sdB binaries might be greater than 15% and the fraction of close substellar companions in sdB binaries may be as high as 8.0%. This would result in a close substellar companion fraction to sdB stars of about 3%. This fraction is much higher than the fraction of brown dwarfs around possible progenitor systems, which are solar-type stars with substellar companions around 1 AU, as well as close binary white dwarfs with brown dwarf companions. This might suggest that common envelope interactions with substellar objects are preferentially followed by a hot subdwarf phase.

Objectively measured physical activity of young Canadian children using accelerometry.

PubMed

Borkhoff, Cornelia M; Heale, Liane D; Anderson, Laura N; Tremblay, Mark S; Maguire, Jonathon L; Parkin, Patricia C; Birken, Catherine S

2015-12-01

The objective of the study was to describe objectively measured physical activity (PA) and sedentary time of infants, toddlers, and preschoolers and determine the proportion meeting Canadian age-specific PA guidelines. Ninety children (47 girls, 43 boys; mean age 32 (range, 4-70) months) attending scheduled health supervision visits and in the TARGet Kids! (The Applied Research Group for Kids) cohort wore an Actical accelerometer for 7 days. Participants with 4 or more valid days were included in the analysis. Time, in mean minutes per day (min/day), spent sedentary and in light PA, moderate to vigorous PA (MVPA), and total PA was determined using published cut-points; age groups were compared using ANOVA. Twenty-three percent of children <18 months (n = 28) and 76% of children aged 18-59 months (n = 45) met the guideline of 180 min/day of total PA; 13% of children ≥60 months (n = 17) met the guideline of 60 min/day of MVPA. Children <18 months spent more of their waking time per day engaged in sedentary behaviours (79%; ∼7.3 h) compared with children aged 18-59 months (63%; ∼6.6 h) and children ≥60 months (58%; ∼6.6 h). In conclusion, most children aged 18-59 months met the Canadian PA guidelines for children aged 0-4 years, whereas few younger than 18 months met the same guidelines. Only 13% of children ≥5 years met their age-specific PA guidelines. Further research is needed to develop, test, and implement effective strategies to promote PA and reduce sedentary behaviour in very young children.

Young Stellar Object VARiability (YSOVAR): Long Timescale Variations in the Mid-infrared

NASA Astrophysics Data System (ADS)

Rebull, L. M.; Cody, A. M.; Covey, K. R.; Günther, H. M.; Hillenbrand, L. A.; Plavchan, P.; Poppenhaeger, K.; Stauffer, J. R.; Wolk, S. J.; Gutermuth, R.; Morales-Calderón, M.; Song, I.; Barrado, D.; Bayo, A.; James, D.; Hora, J. L.; Vrba, F. J.; Alves de Oliveira, C.; Bouvier, J.; Carey, S. J.; Carpenter, J. M.; Favata, F.; Flaherty, K.; Forbrich, J.; Hernandez, J.; McCaughrean, M. J.; Megeath, S. T.; Micela, G.; Smith, H. A.; Terebey, S.; Turner, N.; Allen, L.; Ardila, D.; Bouy, H.; Guieu, S.

2014-11-01

The YSOVAR (Young Stellar Object VARiability) Spitzer Space Telescope observing program obtained the first extensive mid-infrared (3.6 and 4.5 μm) time series photometry of the Orion Nebula Cluster plus smaller footprints in 11 other star-forming cores (AFGL 490, NGC 1333, Mon R2, GGD 12-15, NGC 2264, L1688, Serpens Main, Serpens South, IRAS 20050+2720, IC 1396A, and Ceph C). There are ~29,000 unique objects with light curves in either or both IRAC channels in the YSOVAR data set. We present the data collection and reduction for the Spitzer and ancillary data, and define the "standard sample" on which we calculate statistics, consisting of fast cadence data, with epochs roughly twice per day for ~40 days. We also define a "standard sample of members" consisting of all the IR-selected members and X-ray-selected members. We characterize the standard sample in terms of other properties, such as spectral energy distribution shape. We use three mechanisms to identify variables in the fast cadence data—the Stetson index, a χ2 fit to a flat light curve, and significant periodicity. We also identified variables on the longest timescales possible of six to seven years by comparing measurements taken early in the Spitzer mission with the mean from our YSOVAR campaign. The fraction of members in each cluster that are variable on these longest timescales is a function of the ratio of Class I/total members in each cluster, such that clusters with a higher fraction of Class I objects also have a higher fraction of long-term variables. For objects with a YSOVAR-determined period and a [3.6]-[8] color, we find that a star with a longer period is more likely than those with shorter periods to have an IR excess. We do not find any evidence for variability that causes [3.6]-[4.5] excesses to appear or vanish within our data set; out of members and field objects combined, at most 0.02% may have transient IR excesses.

Sixteen month decline in the 850 micron continuum brightness of the young stellar object HOPS 358 in NGC 2068

NASA Astrophysics Data System (ADS)

Mairs, Steve; Bell, Graham S.; Johnstone, Doug; Herczeg, Gregory J.; Bower, Geoffrey C.; Aikawa, Yuri; Lee, Jeong-Eun; Chen, Huei-Ru Vivien; Hatchell, Jennifer; Kang, Miju; Contreras Pena, Carlos; Scholz, Alexander; Naylor, Tim

2018-04-01

As part of our young stellar object (YSO) sub-mm monthly monitoring programme, the JCMT Transient Survey (Herczeg et al. 2017 ApJ, 849, 43; Johnstone et al. 2018 ApJ, 854, 31), we have uncovered a steady sixteen-month decline in the 850 micron peak brightness of YSO HOPS 358 (R.A.

SCExAO and GPI Y JH band photometry and integral field spectroscopy of the young brown dwarf companion to HD 1160

DOE PAGES

Garcia, Eugenio Victor; Currie, Thayne; Guyon, Olivier; ...

2017-01-10

Here, we present high signal-to-noise ratio, precise Y JH photometry and Y band (0.957–1.120 μm) spectroscopy of HD 1160 B, a young substellar companion discovered from the Gemini NICI Planet Finding Campaign using the Subaru Coronagraphic Extreme Adaptive Optics instrument and the Gemini Planet Imager. HD 1160 B has typical mid-M dwarf-like infrared colors and a spectral type of M5.5more » $${}_{-0.5}^{+1.0}$$, where the blue edge of our Y band spectrum rules out earlier spectral types. Atmospheric modeling suggests HD 1160 B has an effective temperature of 3000–3100 K, a surface gravity of log g = 4–4.5, a radius of 1.55 ± 0.10 R J, and a luminosity of log L/L ⊙ = –2.76 ± 0.05. Neither the primary's Hertzspring–Russell diagram position nor atmospheric modeling of HD 1160 B show evidence for a subsolar metallicity. Interpretation of the HD 1160 B spectroscopy depends on which stellar system components are used to estimate the age. Considering HD 1160 A, B and C jointly, we derive an age of 80–125 Myr, implying that HD 1160 B straddles the hydrogen-burning limit (70–90 M J). If we consider HD 1160 A alone, younger ages (20–125 Myr) and a brown dwarf-like mass (35–90 M J) are possible. Interferometric measurements of the primary, a precise Gaia parallax, and moderate-resolution spectroscopy can better constrain the system's age and how HD 1160 B fits within the context of (sub)stellar evolution.« less

SCExAO and GPI Y JH band photometry and integral field spectroscopy of the young brown dwarf companion to HD 1160

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, Eugenio Victor; Currie, Thayne; Guyon, Olivier

Here, we present high signal-to-noise ratio, precise Y JH photometry and Y band (0.957–1.120 μm) spectroscopy of HD 1160 B, a young substellar companion discovered from the Gemini NICI Planet Finding Campaign using the Subaru Coronagraphic Extreme Adaptive Optics instrument and the Gemini Planet Imager. HD 1160 B has typical mid-M dwarf-like infrared colors and a spectral type of M5.5more » $${}_{-0.5}^{+1.0}$$, where the blue edge of our Y band spectrum rules out earlier spectral types. Atmospheric modeling suggests HD 1160 B has an effective temperature of 3000–3100 K, a surface gravity of log g = 4–4.5, a radius of 1.55 ± 0.10 R J, and a luminosity of log L/L ⊙ = –2.76 ± 0.05. Neither the primary's Hertzspring–Russell diagram position nor atmospheric modeling of HD 1160 B show evidence for a subsolar metallicity. Interpretation of the HD 1160 B spectroscopy depends on which stellar system components are used to estimate the age. Considering HD 1160 A, B and C jointly, we derive an age of 80–125 Myr, implying that HD 1160 B straddles the hydrogen-burning limit (70–90 M J). If we consider HD 1160 A alone, younger ages (20–125 Myr) and a brown dwarf-like mass (35–90 M J) are possible. Interferometric measurements of the primary, a precise Gaia parallax, and moderate-resolution spectroscopy can better constrain the system's age and how HD 1160 B fits within the context of (sub)stellar evolution.« less

The inner-disk and stellar properties of the young stellar object WL 16

NASA Technical Reports Server (NTRS)

Carr, John S.; Tokunaga, Alan T.; Najita, Joan; Shu, Frank H.; Glassgold, Alfred E.

1993-01-01

We present kinematic evidence for a rapidly rotating circumstellar disk around the young stellar object WL 16, based on new high-velocity-resolution data of the v = 2-0 CO bandhead emission. A Keplerian disk provides an excellent fit to the observed profile and requires a projected velocity for the CO-emitting region of roughly 250 km/s at the inner radius and 140 km/s at the outer radius, giving a ratio of the inner to the outer radius of about 0.3. We show that satisfying the constraints imposed by the gas kinematics, the observed CO flux, and the total source luminosity requires the mass of WL 16 to lie between 1.4 and 2.5 solar mass. The inner disk radius for the CO emission must be less than 8 solar radii.

Medium-resolution near-infrared spectroscopy of massive young stellar objects

NASA Astrophysics Data System (ADS)

Pomohaci, R.; Oudmaijer, R. D.; Lumsden, S. L.; Hoare, M. G.; Mendigutía, I.

2017-12-01

We present medium-resolution (R ∼ 7000) near-infrared echelle spectroscopic data for 36 massive young stellar objects (MYSOs) drawn from the Red MSX Source survey. This is the largest sample observed at this resolution at these wavelengths of MYSOs to date. The spectra are characterized mostly by emission from hydrogen recombination lines and accretion diagnostic lines. One MYSO shows photospheric H I absorption, a comparison with spectral standards indicates that the star is an A-type star with a low surface gravity, implying that the MYSOs are probably swollen, as also suggested by evolutionary calculations. An investigation of the Brγ line profiles shows that most are in pure emission, while 13 ± 5 per cent display P Cygni profiles, indicative of outflow, while less than 8 ± 4 per cent have inverse P Cygni profiles, indicative of infall. These values are comparable with investigations into the optically bright Herbig Be stars, but not with those of Herbig Ae and T Tauri stars, consistent with the notion that the more massive stars undergo accretion in a different fashion than lower mass objects that are undergoing magnetospheric accretion. Accretion luminosities and rates as derived from the Br γ line luminosities agree with results for lower mass sources, providing tentative evidence for massive star formation theories based on scaling of low-mass scenarios. We present Br γ/Br12 line profile ratios exploiting the fact that optical depth effects can be traced as a function of Doppler shift across the lines. These show that the winds of MYSOs in this sample are nearly equally split between constant, accelerating and decelerating velocity structures. There are no trends between the types of features we see and bolometric luminosities or near-infrared colours.

Confirming Planetary Mass Candidate Companions in Ophiuchus

NASA Astrophysics Data System (ADS)

Fontanive, Clemence

2016-10-01

We propose for follow-up observations to confirm common proper motion for two candidate planetary mass companions, identified as part of our GO 12944 (PI Allers) search for companions to the youngest ( 0.5 Myr) brown dwarfs in the nearby Ophiuchus star-forming region. If confirmed to be co-moving, these would be among the lowest mass planetary mass companions imaged to date, with estimated masses <5 Jupiter Masses and would be vital benchmark objects for evolutionary models at these young ages. With our multi-band optical and IR photometric approach based on the SpT-Q relation seen for Ophiuchus brown dwarfs (Allers in prep.), we have already estimated the spectral type of our candidate companions. This approach distinguishes substellar objects from background interlopers based on the strength of the 1.4 um water feature robustly observed in MLTY objects but not in reddened background stars - both our candidates show clear evidence of absorption at 1.4 um. If confirmed, these candidate companions would significantly increase the census of young planetary mass companions around extremely young brown dwarfs. These candidate companions are too faint to be observed with ground-based laser guide star adaptive optics (LGS AO) nor is the 1.4 um water feature observable from the ground for such faint objects due to telluric absorption, thus HST is the only telescope in the world suitable for these observations.

X-shooter spectroscopy of young stellar objects. III. Photospheric and chromospheric properties of Class III objects

NASA Astrophysics Data System (ADS)

Stelzer, B.; Frasca, A.; Alcalá, J. M.; Manara, C. F.; Biazzo, K.; Covino, E.; Rigliaco, E.; Testi, L.; Covino, S.; D'Elia, V.

2013-10-01

Context. Traditionally, the chromospheres of late-type stars are studied through their strongest emission lines, Hα and Ca ii HK emission. Our knowledge on the whole emission line spectrum is more elusive as a result of the limited spectral range and sensitivity of most available spectrographs. Aims: We intend to reduce this gap with a comprehensive spectroscopic study of the chromospheric emission line spectrum of a sample of non-accreting pre-main sequence stars (Class III sources). Methods: We analyzed X-shooter/VLT spectra of 24 Class III sources from three nearby star-forming regions (σ Orionis, Lupus III, and TW Hya). We determined the effective temperature, surface gravity, rotational velocity, and radial velocity by comparing the observed spectra with synthetic BT-Settl model spectra. We investigated in detail the emission lines emerging from the stellar chromospheres and combined these data with archival X-ray data to allow for a comparison between chromospheric and coronal emissions. Results: For some objects in the sample the atmospheric and kinematic parameters are presented here for the first time. The effective temperatures are consistent with those derived for the same stars from an empirical calibration with spectral types. Small differences in the surface gravity found between the stars can be attributed to differences in the average age of the three star-forming regions. The strength of lithium absorption and radial velocities confirm the young age of all but one object in the sample (Sz 94). Both X-ray and Hα luminosity as measured in terms of the bolometric luminosity are independent of the effective temperature for early-M stars but decline toward the end of the spectral M sequence. For the saturated early-M stars the average emission level is almost one dex higher for X-rays than for Hα: log (Lx/Lbol) = -2.85 ± 0.36 vs. log (LHα/Lbol) = -3.72 ± 0.21. When all chromospheric emission lines (including the Balmer series up to H11, Ca ii HK

Young Stellar Objects in Lynds 1641: Disks, Accretion, and Star Formation History

NASA Astrophysics Data System (ADS)

Fang, Min; Kim, Jinyoung Serena; van Boekel, Roy; Sicilia-Aguilar, Aurora; Henning, Thomas; Flaherty, Kevin

2013-07-01

We investigate the young stellar objects (YSOs) in the Lynds 1641 (L1641) cloud using multi-wavelength data including Spitzer, WISE, the Two Micron All Sky Survey, and XMM covering ~1390 YSOs across a range of evolutionary stages. In addition, we targeted a sub-sample of YSOs for optical spectroscopy with the MMT/Hectospec and the MMT/Hectochelle. We use these data, along with archival photometric data, to derive spectral types, extinction values, masses, ages, and accretion rates. We obtain a disk fraction of ~50% in L1641. The disk frequency is almost constant as a function of stellar mass with a slight peak at log (M */M ⊙) ≈ -0.25. The analysis of multi-epoch spectroscopic data indicates that the accretion variability of YSOs cannot explain the two orders of magnitude of scatter for YSOs with similar masses. Forty-six new transition disk (TD) objects are confirmed in this work, and we find that the fraction of accreting TDs is lower than for optically thick disks (40%-45% versus 77%-79%, respectively). We confirm our previous result that the accreting TDs have a median accretion rate similar to normal optically thick disks. We confirm that two star formation modes (isolated versus clustered) exist in L1641. We find that the diskless YSOs are statistically older than the YSOs with optically thick disks and the TD objects have a median age that is intermediate between those of the other two populations. We tentatively study the star formation history in L1641 based on the age distribution and find that star formation started to be active 2-3 Myr ago.

A Comparison of Self-Reported and Objective Physical Activity Measures in Young Australian Women.

PubMed

Hartley, Stefanie; Garland, Suzanne; Young, Elisa; Bennell, Kim Louise; Tay, Ilona; Gorelik, Alexandra; Wark, John Dennis

2015-01-01

The evidence for beneficial effects of recommended levels of physical activity is overwhelming. However, 70% of Australians fail to meet these levels. In particular, physical activity participation by women falls sharply between ages 16 to 25 years. Further information about physical activity measures in young women is needed. Self-administered questionnaires are often used to measure physical activity given their ease of application, but known limitations, including recall bias, compromise the accuracy of data. Alternatives such as objective measures are commonly used to overcome this problem, but are more costly and time consuming. To compare the output between the Modified Active Australia Survey (MAAS), the International Physical Activity Questionnaire (IPAQ), and an objective physical activity measure-the SenseWear Armband (SWA)-to evaluate the test-retest reliability of the MAAS and to determine the acceptability of the SWA among young women. Young women from Victoria, Australia, aged 18 to 25 years who had participated in previous studies via Facebook advertising were recruited. Participants completed the two physical activity questionnaires online, immediately before and after wearing the armband for 7 consecutive days. Data from the SWA was blocked into 10-minute activity times. Follow-up IPAQ, MAAS, and SWA data were analyzed by comparing the total continuous and categorical activity scores, while concurrent validity of IPAQ and MAAS were analyzed by comparing follow-up scores. Test-retest reliability of MAAS was analyzed by comparing MAAS total physical activity scores at baseline and follow-up. Participants provided feedback in the follow-up questionnaire about their experience of wearing the armband to determine acceptability of the SWA. Data analyses included graphical (ie, Bland-Altman plot, scatterplot) and analytical (ie, canonical correlation, kappa statistic) methods to determine agreement between MAAS, IPAQ, and SWA data. A total of 58

Substellar Companions to weak-line TTauri Stars

NASA Astrophysics Data System (ADS)

Brandner, W.; Alcala, J. M.; Covino, E.; Frink, S.

1997-05-01

Weak-line TTauri stars, contrary to classical TTauri stars, no longer possess massive circumstellar disks. In weak-line TTauri stars, the circumstellar matter was either accreted onto the TTauri star or has been redistributed. Disk instabilities in the outer disk might result in the formation of brown dwarfs and giant planets. Based on photometric and spectroscopic studies of ROSAT sources, we have selected an initial sample of 200 weak-line TTauri stars in the Chamaeleon T association and the Scorpius Centaurus OB association. In the course of follow-up observations we identified visual and spectroscopic binary stars and excluded them from our final list, as the complex dynamics and gravitational interaction in binary systems might aggravate or even completely inhibit the formation of planets (depending on physical separation of the binary components and their mass-ratio). The membership of individual stars to the associations was established from proper motion studies and radial velocity surveys. Our final sample consists of 70 single weak-line TTauri stars. We have initiated a program to spatially RESOLVE young brown dwarfs and young giant planets as companions to single weak-line TTauri stars using adaptive optics at the ESO 3.6m telescope and HST/NICMOS. In this poster we describe the observing strategy and present first results of our adaptive optics observations.

Star Formation in the Eagle Nebula

NASA Astrophysics Data System (ADS)

Oliveira, J. M.

2008-12-01

M16 (the Eagle Nebula) is a striking star forming region, with a complex morphology of gas and dust sculpted by the massive stars in NGC 6611. Detailed studies of the famous ``elephant trunks'' dramatically increased our understanding of the massive star feedback into the parent molecular cloud. A rich young stellar population (2-3 Myr) has been identified, from massive O-stars down to substellar masses. Deep into the remnant molecular material, embedded protostars, Herbig-Haro objects and maser sources bear evidence of ongoing star formation in the nebula, possibly triggered by the massive cluster members. M 16 is a excellent template for the study of star formation under the hostile environment created by massive O-stars. This review aims at providing an observational overview not only of the young stellar population but also of the gas remnant of the star formation process.

The first H-band spectrum of the giant planet β Pictoris b

DOE PAGES

Chilcote, Jeffrey; Barman, Travis; Fitzgerald, Michael P.; ...

2014-12-12

Using the recently installed Gemini Planet Imager (GPI), we have obtained the first H-band spectrum of the planetary companion to the nearby young star β Pictoris. GPI is designed to image and provide low-resolution spectra of Jupiter-sized, self-luminous planetary companions around young nearby stars. These observations were taken covering the H band (1.65 μm). The spectrum has a resolving power of ~45 and demonstrates the distinctive triangular shape of a cool substellar object with low surface gravity. Using atmospheric models, we find an effective temperature of 1600-1700 K and a surface gravity of log (g) = 3.5-4.5 (cgs units). Thesemore » values agree well with "hot-start" predictions from planetary evolution models for a gas giant with mass between 10 and 12 M Jup and age between 10 and 20 Myr.« less

Bright Localized Near-Infrared Emission at 1-4 AU in the AB Aurigae Disk Revealed by IOTA Closure Phases

NASA Astrophysics Data System (ADS)

Millan-Gabet, R.; Monnier, J. D.; Berger, J.-P.; Traub, W. A.; Schloerb, F. P.; Pedretti, E.; Benisty, M.; Carleton, N. P.; Haguenauer, P.; Kern, P.; Labeye, P.; Lacasse, M. G.; Malbet, F.; Perraut, K.; Pearlman, M.; Thureau, N.

2006-07-01

We report on the detection of localized off-center emission at 1-4 AU in the circumstellar environment of the young stellar object AB Aurigae. We used closure-phase measurements in the near-infrared that were made at the long-baseline interferometer IOTA, the first obtained on a young stellar object using this technique. When probing sub-AU scales, all closure phases are close to zero degrees, as expected given the previously determined size of the AB Aurigae inner-dust disk. However, a clear closure-phase signal of -3.5d +/- 0.5d is detected on one triangle containing relatively short baselines, requiring a high degree of non-point symmetry from emission at larger (AU-sized) scales in the disk. We have not identified any alternative explanation for these closure-phase results, and we demonstrate that a ``disk hot spot'' model can fit our data. We speculate that such detected asymmetric near-infrared emission might arise as a result of localized viscous heating due to a gravitational instability in the AB Aurigae disk, or to the presence of a close stellar companion or accreting substellar object.

A Dual Power Law Distribution for the Stellar Initial Mass Function

NASA Astrophysics Data System (ADS)

Hoffmann, Karl Heinz; Essex, Christopher; Basu, Shantanu; Prehl, Janett

2018-05-01

We introduce a new dual power law (DPL) probability distribution function for the mass distribution of stellar and substellar objects at birth, otherwise known as the initial mass function (IMF). The model contains both deterministic and stochastic elements, and provides a unified framework within which to view the formation of brown dwarfs and stars resulting from an accretion process that starts from extremely low mass seeds. It does not depend upon a top down scenario of collapsing (Jeans) masses or an initial lognormal or otherwise IMF-like distribution of seed masses. Like the modified lognormal power law (MLP) distribution, the DPL distribution has a power law at the high mass end, as a result of exponential growth of mass coupled with equally likely stopping of accretion at any time interval. Unlike the MLP, a power law decay also appears at the low mass end of the IMF. This feature is closely connected to the accretion stopping probability rising from an initially low value up to a high value. This might be associated with physical effects of ejections sometimes (i.e., rarely) stopping accretion at early times followed by outflow driven accretion stopping at later times, with the transition happening at a critical time (therefore mass). Comparing the DPL to empirical data, the critical mass is close to the substellar mass limit, suggesting that the onset of nuclear fusion plays an important role in the subsequent accretion history of a young stellar object.

Young Stellar Object Candidates in the Aquila Rift Region

NASA Astrophysics Data System (ADS)

Zhang, Miao-miao; Wang, Hong-chi; Stecklum, B.

2010-10-01

Using the 2m telescope of the Turingia State Observatory at Tauten-berg (TLS), imaging observations in 3 wavebands (H α, R and I) are performed in the 16 fields in the Aquila Rift region. The observed fields cover about 7 square degrees. Excluding the 3 fields with unqualified data, the photometrical analysis is made for the remaining 13 fields, from which point sources are identified, and finally 7 H α emission-line star candidates are identified by color-color diagrams. The 7 candidates are located in five fields. Three of them are located near the Galactic plane, while the galactic latitudes of the rest are greater than 4°. The 2 M ASS counterparts of the point sources are identified, and the properties of the 7 H α emission-line star candidates are further analyzed by using the two-color diagrams. It is found that the near-infrared radiation from these H α emission-line star candidates has no obvious infrared excess, one of them even falls on the main-sequence branch. This indicates that the H α-emissive young stellar objects (YSOs) are not always accompanied with the infrared excess, and that the results of the H α emission line observation and the infrared excess observation are mutually supplemented. If the 7 H α emission-line star candidates are regarded as YSO candidates, then the number of YSOs in the Aquila Rift region is quite small. The further confirmation of these candidates needs subsequent spectral observations.

DIFFICULTY IN THE FORMATION OF COUNTER-ORBITING HOT JUPITERS FROM NEAR-COPLANAR HIERARCHICAL TRIPLE SYSTEMS: A SUB-STELLAR PERTURBER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xue, Yuxin; Suto, Yasushi, E-mail: yuxin@utap.phys.s.u-tokyo.ac.jp

2016-03-20

Among 100 transiting planets with a measured projected spin–orbit angle λ, several systems are suggested to be counter-orbiting. While these cases may be due to the projection effect, the mechanism that produces a counter-orbiting planet has not been established. A promising scenario for counter-orbiting planets is the extreme eccentricity evolution in near-coplanar hierarchical triple systems with eccentric inner and outer orbits. We examine this scenario in detail by performing a series of systematic numerical simulations, and consider the possibility of forming hot Jupiters (HJs), especially a counter-orbiting one under this mechanism with a distant sub-stellar perturber. We incorporate quadrupole andmore » octupole secular gravitational interaction between the two orbits, and also short-range forces (correction for general relativity, star and inner planetary tide, and rotational distortion) simultaneously. We find that most systems are tidally disrupted and that a small fraction of the surviving planets turn out to be prograde. The formation of counter-orbiting HJs in this scenario is possible only in a very restricted parameter region, and thus is very unlikely in practice.« less

Near-infrared integral field spectroscopy of massive young stellar objects

NASA Astrophysics Data System (ADS)

Murakawa, K.; Lumsden, S. L.; Oudmaijer, R. D.; Davies, B.; Wheelwright, H. E.; Hoare, M. G.; Ilee, J. D.

2013-11-01

We present medium-resolution (R ≈ 5300) K-band integral field spectroscopy of six massive young stellar objects (MYSOs). The targets are selected from the Red MSX Source (RMS) survey, and we used the ALTAIR adaptive optics assisted Near-Infrared Integral Field Spectrometer (NIFS) mounted on the Gemini North telescope. The data show various spectral line features including Brγ, CO, H2 and He I. The Brγ line is detected in emission in all objects with vFWHM ˜ 100-200 km s-1. V645 Cyg shows a high-velocity P-Cygni profile between -800 and -300 km s-1. We performed three-dimensional spectroastrometry to diagnose the circumstellar environment in the vicinity of the central stars using the Brγ line. We measured the centroids of the velocity components with sub-mas precision. The centroids allow us to discriminate the blueshifted and redshifted components in a roughly east-west direction in both IRAS 18151-1208 and S106 in Brγ. This lies almost perpendicular to observed larger scale outflows. We conclude, given the widths of the lines and the orientation of the spectroastrometric signature, that our results trace a disc wind in both IRAS 18151-1208 and S106. The CO ν = 2-0 absorption lines at low J transitions are detected in IRAS 18151-1208 and AFGL 2136. We analysed the velocity structure of the neutral gas discs, which we find to have nearly Keplerian motions. In IRAS 18151-1208, the absorption centroids of the blueshifted and redshifted components are separated in a direction of north-east to south-west, nearly perpendicular to that of the larger scale H2 jet. The position-velocity relations of these objects can be reproduced with central masses of 30 M⊙ for IRAS 18151-1208 and 20 M⊙ for AFGL 2136. We also detect CO ν = 2-0 bandhead emission in IRAS 18151-1208, S106 and V645 Cyg. The results can be fitted reasonably with a Keplerian rotation model, with masses of 15, 20 and 20 M⊙, respectively. These results for a sample of MYSOs can be explained with

THE TOP 10 SPITZER YOUNG STELLAR OBJECTS IN 30 DORADUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walborn, Nolan R.; Barba, Rodolfo H.; Sewilo, Marta M., E-mail: walborn@stsci.edu, E-mail: rbarba@dfuls.cl, E-mail: mmsewilo@pha.jhu.edu

2013-04-15

The most luminous Spitzer point sources in the 30 Doradus triggered second generation are investigated coherently in the 3-8 {mu}m region. Remarkable diversity and complexity in their natures are revealed. Some are also among the brightest JHK sources, while others are not. Several of them are multiple when examined at higher angular resolutions with Hubble Space Telescope NICMOS and WFPC2/WFC3 as available, or with VISTA/VMC otherwise. One is a dusty compact H II region near the far northwestern edge of the complex, containing a half-dozen bright I-band sources. Three others appear closely associated with luminous WN stars and causal connectionsmore » are suggested. Some are in the heads of dust pillars oriented toward R136, as previously discussed from the NICMOS data. One resides in a compact cluster of much fainter sources, while another appears monolithic at the highest resolutions. Surprisingly, one is the brighter of the two extended ''mystery spots'' associated with Knot 2 of Walborn et al. Masses are derived from young stellar object models for unresolved sources and lie in the 10-30 M{sub Sun} range. Further analysis of the IR sources in this unique region will advance understanding of triggered massive star formation, perhaps in some unexpected and unprecedented ways.« less

A spectrophotometric method for detecting substellar companions to late-type M stars

NASA Astrophysics Data System (ADS)

Oetiker, Brian Glen

for a broad range of companion masses, may result in a better understanding of the substellar mass function.

X-shooter spectroscopy of young stellar objects. VI. H I line decrements

NASA Astrophysics Data System (ADS)

Antoniucci, S.; Nisini, B.; Giannini, T.; Rigliaco, E.; Alcalá, J. M.; Natta, A.; Stelzer, B.

2017-03-01

Context. Hydrogen recombination emission lines commonly observed in accreting young stellar objects represent a powerful tracer for the gas conditions in the circumstellar structures (accretion columns, and winds or jets). Aims: Here we perform a study of the H I decrements and line profiles, from the Balmer and Paschen H I lines detected in the X-shooter spectra of a homogeneous sample of 36 T Tauri objects in Lupus, the accretion and stellar properties of which were already derived in a previous work. We aim to obtain information on the H I gas physical conditions to delineate a consistent picture of the H I emission mechanisms in pre-main sequence low-mass stars (M∗< 2 M⊙). Methods: We have empirically classified the sources based on their H I line profiles and decrements. We identified four Balmer decrement types (which we classified as 1, 2, 3, and 4) and three Paschen decrement types (A, B, and C), characterised by different shapes. We first discussed the connection between the decrement types and the source properties and then compared the observed decrements with predictions from recently published local line excitation models. Results: We identify a few groups of sources that display similar H I properties. One third of the objects show lines with narrow symmetric profiles, and present similar Balmer and Paschen decrements (straight decrements, types 2 and A). Lines in these sources are consistent with optically thin emission from gas with hydrogen densities of order 109 cm-3 and 5000 < T < 15 000 K. These objects are associated with low mass accretion rates. Type 4 (L-shaped) Balmer and type B Paschen decrements are found in conjunction with very wide line profiles and are characteristic of strong accretors, with optically thick emission from high-density gas (log nH > 11 cm-3). Type 1 (curved) Balmer decrements are observed only in three sub-luminous sources viewed edge-on, so we speculate that these are actually type 2 decrements that are reddened

Identification of the central compact object in the young supernova remnant 1E 0102.2-7219

NASA Astrophysics Data System (ADS)

Vogt, Frédéric P. A.; Bartlett, Elizabeth S.; Seitenzahl, Ivo R.; Dopita, Michael A.; Ghavamian, Parviz; Ruiter, Ashley J.; Terry, Jason P.

2018-04-01

Oxygen-rich young supernova remnants1 are valuable objects for probing the outcome of nucleosynthetic processes in massive stars, as well as the physics of supernova explosions. Observed within a few thousand years after the supernova explosion2, these systems contain fast-moving oxygen-rich and hydrogen-poor filaments visible at optical wavelengths: fragments of the progenitor's interior expelled at a few thousand kilometres per second during the supernova explosion. Here we report the identification of the compact object in the supernova remnant 1E 0102.2-7219 in reprocessed Chandra X-ray Observatory data, enabled by the discovery of a ring-shaped structure visible primarily in optical recombination lines of Ne i and O i. The optical ring has a radius of (2.10 ± 0.35)″ ≡ (0.63 ± 0.11) pc, and is expanding at a velocity of 90 .5-30+40 km s-1. It surrounds an X-ray point source with an intrinsic X-ray luminosity Li (1.2-2.0 keV) = (1.4 ± 0.2) × 1033 erg s-1. The energy distribution of the source indicates that this object is an isolated neutron star: a central compact object akin to those present in the Cas A3-5 and Pup A6 supernova remnants, and the first of its kind to be identified outside of our Galaxy.

Identification of the central compact object in the young supernova remnant 1E 0102.2-7219

NASA Astrophysics Data System (ADS)

Vogt, Frédéric P. A.; Bartlett, Elizabeth S.; Seitenzahl, Ivo R.; Dopita, Michael A.; Ghavamian, Parviz; Ruiter, Ashley J.; Terry, Jason P.

2018-06-01

Oxygen-rich young supernova remnants1 are valuable objects for probing the outcome of nucleosynthetic processes in massive stars, as well as the physics of supernova explosions. Observed within a few thousand years after the supernova explosion2, these systems contain fast-moving oxygen-rich and hydrogen-poor filaments visible at optical wavelengths: fragments of the progenitor's interior expelled at a few thousand kilometres per second during the supernova explosion. Here we report the identification of the compact object in the supernova remnant 1E 0102.2-7219 in reprocessed Chandra X-ray Observatory data, enabled by the discovery of a ring-shaped structure visible primarily in optical recombination lines of Ne i and O i. The optical ring has a radius of (2.10 ± 0.35)″ ≡ (0.63 ± 0.11) pc, and is expanding at a velocity of 90 .5-30+40 km s-1. It surrounds an X-ray point source with an intrinsic X-ray luminosity Li (1.2-2.0 keV) = (1.4 ± 0.2) × 1033 erg s-1. The energy distribution of the source indicates that this object is an isolated neutron star: a central compact object akin to those present in the Cas A3-5 and Pup A6 supernova remnants, and the first of its kind to be identified outside of our Galaxy.

NuSTAR Observations of X-Ray Flares from Young Stellar Objects

NASA Astrophysics Data System (ADS)

Vievering, Juliana; Glesener, Lindsay; Grefenstette, Brian; Smith, David

2018-01-01

Young stellar objects (YSOs), which tend to flare more frequently and at higher temperatures than what is typically observed on Sun-like stars, are excellent targets for studying the physical processes behind large flaring events. In the hard x-ray regime, radiation can penetrate through dense circumstellar material, and it is possible to measure thermal emission from hot plasma and to search for nonthermal emission from accelerated particles, which are key components for understanding the nature of energy release in these flares. Additionally, high-energy x-ray emission can ionize material in the disk, which may have implications for planet formation. To investigate hard x-ray emission from YSOs, three 50ks observations of a star-forming region called rho Ophiuchi have been taken with the Nuclear Spectroscopic Telescope Array (NuSTAR). Through use of direct focusing optics, NuSTAR provides unprecedented sensitivity in the hard x-ray regime, making these YSO observations the first of their kind. Multiple stellar flares have been identified in the data set; here we present the current spectral and timing analyses of the brightest of the these events, exploring the way energy is released as well as the effects of these large flares on the surrounding environment.

Parallels between Action-Object Mapping and Word-Object Mapping in Young Children

ERIC Educational Resources Information Center

Riggs, Kevin J.; Mather, Emily; Hyde, Grace; Simpson, Andrew

2016-01-01

Across a series of four experiments with 3- to 4-year-olds we demonstrate how cognitive mechanisms supporting noun learning extend to the mapping of actions to objects. In Experiment 1 (n = 61) the demonstration of a novel action led children to select a novel, rather than a familiar object. In Experiment 2 (n = 78) children exhibited long-term…

Chronic methylphenidate-effects over circadian cycle of young and adult rats submitted to open-field and object recognition tests.

PubMed

Gomes, Karin M; Souza, Renan P; Valvassori, Samira S; Réus, Gislaine Z; Inácio, Cecília G; Martins, Márcio R; Comim, Clarissa M; Quevedo, João

2009-11-01

In this study age-, circadian rhythm- and methylphenidate administration- effect on open field habituation and object recognition were analyzed. Young and adult male Wistar rats were treated with saline or methylphenidate 2.0 mg/kg for 28 days. Experiments were performed during the light and the dark cycle. Locomotor activity was significantly altered by circadian cycle and methylphenidate treatment during the training session and by drug treatment during the testing session. Exploratory activity was significantly modulated by age during the training session and by age and drug treatment during the testing session. Object recognition memory was altered by cycle at the training session; by age 1.5 h later and by cycle and age 24 h after the training session. These results show that methylphenidate treatment was the major modulator factor on open-field test while cycle and age had an important effect on object recognition experiment.

The Pan-STARRS1 Proper-motion Survey for Young Brown Dwarfs in Nearby Star-forming Regions. I. Taurus Discoveries and a Reddening-free Classification Method for Ultracool Dwarfs

NASA Astrophysics Data System (ADS)

Zhang, Zhoujian; Liu, Michael C.; Best, William M. J.; Magnier, Eugene A.; Aller, Kimberly M.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Metcalfe, N.; Wainscoat, R. J.; Waters, C.

2018-05-01

We are conducting a proper-motion survey for young brown dwarfs in the Taurus-Auriga molecular cloud based on the Pan-STARRS1 3π Survey. Our search uses multi-band photometry and astrometry to select candidates, and is wider (370 deg2) and deeper (down to ≈3 M Jup) than previous searches. We present here our search methods and spectroscopic follow-up of our high-priority candidates. Since extinction complicates spectral classification, we have developed a new approach using low-resolution (R ≈ 100) near-infrared spectra to quantify reddening-free spectral types, extinctions, and gravity classifications for mid-M to late-L ultracool dwarfs (≲100–3 M Jup in Taurus). We have discovered 25 low-gravity (VL-G) and the first 11 intermediate-gravity (INT-G) substellar (M6–L1) members of Taurus, constituting the largest single increase of Taurus brown dwarfs to date. We have also discovered 1 new Pleiades member and 13 new members of the Perseus OB2 association, including a candidate very wide separation (58 kau) binary. We homogeneously reclassify the spectral types and extinctions of all previously known Taurus brown dwarfs. Altogether our discoveries have thus far increased the substellar census in Taurus by ≈40% and added three more L-type members (≲5–10 M Jup). Most notably, our discoveries reveal an older (>10 Myr) low-mass population in Taurus, in accord with recent studies of the higher-mass stellar members. The mass function appears to differ between the younger and older Taurus populations, possibly due to incompleteness of the older stellar members or different star formation processes.

A visual processing advantage for young-adolescent deaf observers: Evidence from face and object matching tasks

PubMed Central

Megreya, Ahmed M.; Bindemann, Markus

2017-01-01

It is unresolved whether the permanent auditory deprivation that deaf people experience leads to the enhanced visual processing of faces. The current study explored this question with a matching task in which observers searched for a target face among a concurrent lineup of ten faces. This was compared with a control task in which the same stimuli were presented upside down, to disrupt typical face processing, and an object matching task. A sample of young-adolescent deaf observers performed with higher accuracy than hearing controls across all of these tasks. These results clarify previous findings and provide evidence for a general visual processing advantage in deaf observers rather than a face-specific effect. PMID:28117407

Children and Objects: Affection and Infection

ERIC Educational Resources Information Center

Jones, Liz; MacLure, Maggie; Holmes, Rachel; MacRae, Christina

2012-01-01

This paper considers young children's (aged 3-5 years) relations with objects, and in particular objects that are brought from home to school. We begin by considering the place of objects within early years classrooms and their relationship to children's education before considering why some objects are often separated from their owners on entry…

Low-Mass Star Formation and the Initial Mass Function in Young Clusters

NASA Astrophysics Data System (ADS)

Luhman, Kevin Lee

I have used optical and near-infrared spectroscopy and imaging to measure spectral types and luminosities for young (/tau<10 Myr), embedded (AV=0[-]50), low-mass (0.1-1 Msolar) stars in three nearby (d<300 pc) clusters: L1495E, IC 348, and ρ Ophiuchi. In conjunction with theoretical evolutionary tracks, I have derived the star formation history and initial mass function for each stellar population. A large number of brown dwarf candidates have been identified in the photometry, several of which are confirmed through spectroscopy. Finally, I have measured the frequency and survival times of circumstellar disks and investigated the photometric and spectroscopic properties of protostars. In S 2, I apply observational tests to the available sets of evolutionary models for low-mass stars, concluding that the calculations of D'Antona & Mazzitelli are preferred for the range of masses and ages considered here. In S 3 and S 4, I examine in detail the spectroscopic characteristics and substellar nature of two brown dwarf candidates. The study then expands to include the populations within the clusters L1495E (S 5), IC 348 (S 6), and ρ Ophiuchi (S 7). In S 8, I briefly discuss the past, present, and future of scientific research related to this thesis.

Exoplanet Meteorology: Characterizing the Atmospheres of Directly Imaged Sub-Stellar Objects

NASA Astrophysics Data System (ADS)

Rajan, Abhijith; Gemini Planet Imager, Extrasolar Planets and Systems Imaging Group

2018-01-01

I study the structure, composition and dynamic evolution of directly imaged exoplanet and brown dwarf atmospheres, using spectrophotometric data collected from a range of ground and space based instrumentation. As part of my dissertation, I led studies exploring the atmospheres of brown dwarfs to search for weather variations, and characterized the near and mid infrared SEDs of imaged exoplanets to estimate their fundamental parameters. To understand the evolution of weather on brown dwarfs we conducted a multi-epoch study monitoring of 4 ultracool, T5 - Y0, brown dwarfs in the J-band to search for photometric variability. These cool brown dwarfs are predicted to have salt and sulfide clouds condensing in their upper atmosphere. The study found that cool brown dwarfs, fit with higher opacity clouds, were more likely to be variable. Through data taken with the Hubble Space Telescope and Gemini telescope we characterized the atmospheres of directly imaged exoplanets. For HR 8799, in near IR wavelengths unobservable from the ground, we constrained the presence of clouds in the outer planets. As a member of the Gemini Planet Imager Exoplanet Survey team, I analyzed archival HST data and examined the near-infrared colors of HD 106906b as seen with GPI, concluding that the companion shows weak evidence of a circumplanetary dust disk or cloud. Finally, by combining data spanning 1 - 5 um for the low mass Jupiter-like exoplanet, 51 Eri b, we found a cool effective temperature best fit by a patchy cloud atmosphere. This makes the planet an excellent candidate for future variability studies with the James Webb Space Telescope.

Initial Results from the Palomar Adaptive Optics Survey of Young Solar-Type Stars: A Brown Dwarf and Three Stellar Companions

NASA Astrophysics Data System (ADS)

Metchev, Stanimir A.; Hillenbrand, Lynne A.

2004-12-01

We present first results from the Palomar Adaptive Optics Survey of Young Stars conducted at the Hale 5 m telescope. Through direct imaging we have discovered a brown dwarf and two low-mass stellar companions to the young solar-type stars HD 49197, HD 129333 (EK Dra), and V522 Per and confirmed a previously suspected companion to RX J0329.1+0118 (Sterzik et al.), at respective separations of 0.95" (43 AU), 0.74" (25 AU), 2.09" (400 AU), and 3.78" (380 AU). Physical association of each binary system is established through common proper motion and/or low-resolution infrared spectroscopy. Based on the companion spectral types, we estimate their masses at 0.06, 0.20, 0.13, and 0.20 Msolar, respectively. From analysis of our imaging data combined with archival radial velocity data, we find that the spatially resolved companion to HD 129333 is potentially identical to the previously identified spectroscopic companion to this star (Duquennoy & Mayor). However, a discrepancy with the absolute magnitude suggests that the two companions could also be distinct, with the resolved one being the outermost component of a triple system. The brown dwarf HD 49197B is a new member of a growing list of directly imaged substellar companions at 10-1000 AU separations from main-sequence stars, indicating that such brown dwarfs may be more common than initially speculated.

Objectively Measured Physical Activity and Sedentary Time during Childhood, Adolescence and Young Adulthood: A Cohort Study

PubMed Central

Ortega, Francisco B.; Hurtig-Wennlöf, Anita; Mäestu, Jarek; Löf, Marie; Harro, Jaanus; Bellocco, Rino; Labayen, Idoia; Veidebaum, Toomas; Sjöström, Michael

2013-01-01

Background To know how moderate-to-vigorous physical activity (MVPA) and sedentary time change across lifespan periods is needed for designing successful lifestyle interventions. We aimed to study changes in objectively measured (accelerometry) MVPA and sedentary time from childhood to adolescence and from adolescence to young adulthood. Methods Estonian and Swedish participants from the European Youth Heart Study aged 9 and 15 years at baseline (N = 2312) were asked to participate in a second examination 6 (Sweden) to 9/10 (Estonia) years later. 1800 participants with valid accelerometer data were analyzed. Results MVPA decreased from childhood to adolescence (−1 to −2.5 min/d per year of follow-up, P = 0.01 and <0.001, for girls and boys respectively) and also from adolescence to young adulthood (−0.8 to −2.2 min/d per year, P = 0.02 and <0.001 for girls and boys, respectively). Sedentary time increased from childhood to adolescence (+15 and +20 min/d per year, for girls and boys respectively, P<0.001), with no substantial change from adolescence to young adulthood. Changes in both MVPA and sedentary time were greater in Swedish than in Estonian participants and in boys than in girls. The magnitude of the change observed in sedentary time was 3–6 time larger than the change observed in MVPA. Conclusions The decline in MVPA (overall change = 30 min/d) and increase sedentary time (overall change = 2∶45 h/d) observed from childhood to adolescence are of concern and might increase the risk of developing obesity and other chronic diseases later in life. These findings substantially contribute to understand how key health-related behaviors (physical activity and sedentary) change across important periods of life. PMID:23637772

ALMA Measurements of Circumstellar Material in the GQ Lup System

NASA Astrophysics Data System (ADS)

Wilner, David J.; MacGregor, Meredith A.; Czekala, Ian; Andrews, Sean M.; Dai, Yu Sophia; Herczeg, Gregory; Kratter, Kaitlin M.; Kraus, Adam L.; Ricci, Luca; Testi, Leonardo

2017-01-01

We present ALMA observations of the GQ Lup system, a young Sun-like star with a substellar mass companion in a wide-separation orbit. These observations of 870 micron continuum and CO J=3-2 line emission with beam 0.3 arcsec (45 AU) resolve the disk of dust and gas surrounding the primary star, GQ Lup A, and provide deep limits on any circumplanetary disk surrounding the companion, GQ Lup b. The 3 sigma upper limit on the 870 micron flux density of < 0.15 mJy implies an upper limit on the GQ Lup b disk mass of about 0.04 solar masses for standard assumptions about optically thin dust emission. Given the non-detection of a circumplanetary disk around GQ Lup b, and other similar systems observed by ALMA, we discuss implications for formation mechanisms of wide-separation substellar companions.

43 CFR 32.3 - Program purpose and objectives.

Code of Federal Regulations, 2014 CFR

2014-10-01

... ESTABLISHING YOUNG ADULT CONSERVATION CORPS (YACC) PROGRAM § 32.3 Program purpose and objectives. It is the purpose of the Young Adult Conservation Corps to provide employment and other benefits to youths of both...

43 CFR 32.3 - Program purpose and objectives.

Code of Federal Regulations, 2010 CFR

2010-10-01

... ESTABLISHING YOUNG ADULT CONSERVATION CORPS (YACC) PROGRAM § 32.3 Program purpose and objectives. It is the purpose of the Young Adult Conservation Corps to provide employment and other benefits to youths of both...

NEW EXTINCTION AND MASS ESTIMATES FROM OPTICAL PHOTOMETRY OF THE VERY LOW MASS BROWN DWARF COMPANION CT CHAMAELEONTIS B WITH THE MAGELLAN AO SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Ya-Lin; Close, Laird M.; Males, Jared R.

We used the Magellan adaptive optics system and its VisAO CCD camera to image the young low mass brown dwarf companion CT Chamaeleontis B for the first time at visible wavelengths. We detect it at r', i', z', and Y{sub S}. With our new photometry and T {sub eff} ∼ 2500 K derived from the shape of its K-band spectrum, we find that CT Cha B has A{sub V} = 3.4 ± 1.1 mag, and a mass of 14-24 M{sub J} according to the DUSTY evolutionary tracks and its 1-5 Myr age. The overluminosity of our r' detection indicates thatmore » the companion has significant Hα emission and a mass accretion rate ∼6 × 10{sup –10} M {sub ☉} yr{sup –1}, similar to some substellar companions. Proper motion analysis shows that another point source within 2'' of CT Cha A is not physical. This paper demonstrates how visible wavelength adaptive optics photometry (r', i', z', Y{sub S}) allows for a better estimate of extinction, luminosity, and mass accretion rate of young substellar companions.« less

New Extinction and Mass Estimates from Optical Photometry of the Very Low Mass Brown Dwarf Companion CT Chamaeleontis B with the Magellan AO System

NASA Astrophysics Data System (ADS)

Wu, Ya-Lin; Close, Laird M.; Males, Jared R.; Barman, Travis S.; Morzinski, Katie M.; Follette, Katherine B.; Bailey, Vanessa; Rodigas, Timothy J.; Hinz, Philip; Puglisi, Alfio; Xompero, Marco; Briguglio, Runa

2015-03-01

We used the Magellan adaptive optics system and its VisAO CCD camera to image the young low mass brown dwarf companion CT Chamaeleontis B for the first time at visible wavelengths. We detect it at r', i', z', and YS . With our new photometry and T eff ~ 2500 K derived from the shape of its K-band spectrum, we find that CT Cha B has AV = 3.4 ± 1.1 mag, and a mass of 14-24 MJ according to the DUSTY evolutionary tracks and its 1-5 Myr age. The overluminosity of our r' detection indicates that the companion has significant Hα emission and a mass accretion rate ~6 × 10-10 M ⊙ yr-1, similar to some substellar companions. Proper motion analysis shows that another point source within 2'' of CT Cha A is not physical. This paper demonstrates how visible wavelength adaptive optics photometry (r', i', z', YS ) allows for a better estimate of extinction, luminosity, and mass accretion rate of young substellar companions. This paper includes data gathered with the 6.5 m Magellan Clay Telescope at Las Campanas Observatory, Chile.

A circumstellar disk associated with a massive protostellar object.

PubMed

Jiang, Zhibo; Tamura, Motohide; Fukagawa, Misato; Hough, Jim; Lucas, Phil; Suto, Hiroshi; Ishii, Miki; Yang, Ji

2005-09-01

The formation process for stars with masses several times that of the Sun is still unclear. The two main theories are mergers of several low-mass young stellar objects, which requires a high stellar density, or mass accretion from circumstellar disks in the same way as low-mass stars are formed, accompanied by outflows during the process of gravitational infall. Although a number of disks have been discovered around low- and intermediate-mass young stellar objects, the presence of disks around massive young stellar objects is still uncertain and the mass of the disk system detected around one such object, M17, is disputed. Here we report near-infrared imaging polarimetry that reveals an outflow/disk system around the Becklin-Neugebauer protostellar object, which has a mass of at least seven solar masses (M(o)). This strongly supports the theory that stars with masses of at least 7M(o) form in the same way as lower mass stars.

An Infrared Search for Young Stellar Objects in IC 1396

NASA Astrophysics Data System (ADS)

Johnson, Chelen H.; Linahan, Marcella; Gibbs, John; Rebull, Luisa M.; Archibald, Andrew R.; Dickmann, Samantha Rose; Hart, Erica A.; Hedlund, Audrey R.; Hilfer, Shannon L.; Lacher, Thomas; McKernan, John T.; Medeiros, Emma M.; Nelson, Samantha Brooks; O'Leary, Harrison; Peña, Nicholas D.; Peterson, Alexis; Reader, Livia K.; Ropinski, Brandi Lucia; Scarpa, Gabriella; Sundeen, Kiera A.; Takara, Amber L.; Thiel, Theresa

2017-01-01

About 700 parsecs away from Earth, IC1396 lies along the galactic plane, in the direction of the constellation Cepheus, and includes many dark nebulae, including the Elephant’s Trunk Nebula. IC 1396A has been examined with a variety of telescopes, including Spitzer, 2MASS, IPHAS, Chandra, and WISE. The YSOVAR project (Rebull et al. 2014) also has Spitzer monitoring data in this region at 3.6 and 4.5 microns. Our team has merged these catalogs and identified candidate YSOs using IR color selection, X-ray detection, and variability metrics. In order to interpret the YSOVAR light curves, it is critical to understand which of the 700+ YSO candidates in this region are likely YSOs, and which are foreground/background stars or are extragalactic objects. As a first attempt to confirm these candidate YSOs, we have created spectral energy distributions (SEDs) for wavelengths from IPHAS r band to 24 microns, which we use, coupled with image inspection, to confirm (or refute) YSO candidates from this list of identified YSO candidates. We will then compare our vetted list of YSO candidates to the lists of YSO candidates already identified in the literature in this region. The goal of this study is to identify candidate YSO sources, as well as support the greater understanding of the variety, evolution and variability of young stars. This project is a collaborative effort of high school students from three states. They analyzed data individually and later collaborated online to compare results. This project is the result of many years of work with the NASA/IPAC Teacher Archive Research Program (NITARP).

Planets around Low-mass Stars. III. A Young Dusty L Dwarf Companion at the Deuterium-burning Limit

NASA Astrophysics Data System (ADS)

Bowler, Brendan P.; Liu, Michael C.; Shkolnik, Evgenya L.; Dupuy, Trent J.

2013-09-01

We report the discovery of an L-type companion to the young M3.5V star 2MASS J01225093-2439505 at a projected separation of 1.''45 (≈52 AU) as part of our adaptive optics imaging search for extrasolar giant planets around young low-mass stars. 2MASS 0122-2439 B has very red near-infrared colors similar to the HR 8799 planets and the reddest known young/dusty L dwarfs in the field. Moderate-resolution (R ≈ 3800) 1.5-2.4 μm spectroscopy reveals a near-infrared spectral type of L4-L6 and an angular H-band shape, confirming its cool temperature and young age. The kinematics of 2MASS 0122-2439 AB are marginally consistent with members of the ~120 Myr AB Dor young moving group based on the photometric distance to the primary (36 ± 4 pc) and our radial velocity measurement of 2MASS 0122-2439 A from Keck/HIRES. We adopt the AB Dor group age for the system, but the high energy emission, lack of Li I λ6707 absorption, and spectral shape of 2MASS 0122-2439 B suggest a range of ~10-120 Myr is possible. The age and luminosity of 2MASS 0122-2439 B fall in a strip where "hot-start" evolutionary model mass tracks overlap as a result of deuterium burning. Several known substellar companions also fall in this region (2MASS J0103-5515 ABb, AB Pic b, κ And b, G196-3 B, SDSS 2249+0044 B, LP 261-75 B, HD 203030 B, and HN Peg B), but their dual-valued mass predictions have largely been unrecognized. The implied mass of 2MASS 0122-2439 B is ≈12-13 M Jup or ≈22-27 M Jup if it is an AB Dor member, or possibly as low as 11 M Jup if the wider age range is adopted. Evolutionary models predict an effective temperature for 2MASS 0122-2439 B that corresponds to spectral types near the L/T transition (≈1300-1500 K) for field objects. However, we find a mid-L near-infrared spectral type, indicating that 2MASS 0122-2439 B represents another case of photospheric dust being retained to cooler temperatures at low surface gravities, as seen in the spectra of young (8-30 Myr) planetary

Fundamental Parameters Of The Lowest Mass Stars To The Highest Mass Planets

NASA Astrophysics Data System (ADS)

Filippazzo, Joseph C.

2016-09-01

The physical and atmospheric properties of ultracool dwarfs are deeply entangled due to the degenerate effects of mass, age, metallicity, clouds and dust, activity, rotation, and possibly even formation mechanism on observed spectra. Accurate determination of funda- mental parameters for a wide diversity of objects at the low end of the initial mass function (IMF) is thus crucial to testing stellar and planetary formation theories. To determine these quantities, we constructed and flux calibrated nearly-complete spectral energy distributions (SEDs) for 234 M, L, T, and Y dwarfs using published parallaxes and (0.3-40 \\mu m) spectra and photometry. From these homogeneous SEDs, we calculated bolometric luminosity ((L_\\text{bol})), effective temperature ((T_\\text{off})), mass, surface gravity, radius, spectral indexes, synthetic photometry, and bolometric corrections (BCs) for each object. We used these results to derive (L_\\text{bol}), (T_\\text{eff}), and BC polynomial relations across the entire very-low-mass star/brown dwarf/planetary mass regime. We use a subsample of objects with age constraints based on nearby young moving group membership, companionship with a young star, or spectral signatures of low surface gravity to define new age-sensitive diagnostics and characterize the reddening of young substellar atmospheres as a redistribution of flux from the near-infrared (NIR) into the mid-infrared (MIR). Consequently we find the SED flux pivots at K-band, making BCK as a function of spectral type a reliable, age-independent relationship. We find that young L dwarfs are systematically 300 K cooler than field age objects of the same spectral type and up to 600 K cooler than field age objects of the same absolute H magnitude. These findings are used to create prescriptions for the reliable and efficient characterization of new ultracool dwarfs using heterogeneous and limited spectral data.

Infants' Use of Category Knowledge and Object Attributes when Segregating Objects at 8.5 Months of Age

ERIC Educational Resources Information Center

Needham, Amy; Cantlon, Jessica F.; Ormsbee Holley, Susan M.

2006-01-01

The current research investigates infants' perception of a novel object from a category that is familiar to young infants: key rings. We ask whether experiences obtained outside the lab would allow young infants to parse the visible portions of a partly occluded key ring display into one single unit, presumably as a result of having categorized it…

Mid-infrared interferometry towards the massive young stellar object CRL 2136: inside the dust rim

NASA Astrophysics Data System (ADS)

de Wit, W. J.; Hoare, M. G.; Oudmaijer, R. D.; Nürnberger, D. E. A.; Wheelwright, H. E.; Lumsden, S. L.

2011-02-01

Context. Establishing the importance of circumstellar disks and their properties is crucial to fully understand massive star formation. Aims: We aim to spatially resolve the various components that make-up the accretion environment of a massive young stellar object (⪉100 AU), and reproduce the emission from near-infrared to millimeter wavelengths using radiative transfer codes. Methods: We apply mid-infrared spectro-interferometry to the massive young stellar object CRL 2136. The observations were performed with the Very Large Telescope Interferometer and the MIDI instrument at a 42 m baseline probing angular scales of 50 milli-arcseconds. We model the observed visibilities in parallel with diffraction-limited images at both 24.5 μm and in the N-band (with resolutions of 0.6´´and 0.3´´, respectively), as well as the spectral energy distribution. Results: The arcsec-scale spatial information reveals the well-resolved emission from the dusty envelope. By simultaneously modelling the spatial and spectral data, we find that the bulk of the dust emission occurs at several dust sublimation radii (approximately 170 AU). This reproduces the high mid-infrared fluxes and at the same time the low visibilities observed in the MIDI data for wavelengths longward of 8.5 μm. However, shortward of this wavelength the visibility data show a sharp up-turn indicative of compact emission. We discuss various potential sources of this emission. We exclude a dust disk being responsible for the observed spectral imprint on the visibilities. A cool supergiant star and an accretion disk are considered and both shown to be viable origins of the compact mid-infrared emission. Conclusions: We propose that CRL 2136 is embedded in a dusty envelope, which truncates at several times the dust sublimation radius. A dust torus is manifest in the equatorial region. We find that the spectro-interferometric N-band signal can be reproduced by either a gaseous disk or a bloated central star. If the

CFBDSIR 2149-0403: young isolated planetary-mass object or high-metallicity low-mass brown dwarf?

NASA Astrophysics Data System (ADS)

Delorme, P.; Dupuy, T.; Gagné, J.; Reylé, C.; Forveille, T.; Liu, M. C.; Artigau, E.; Albert, L.; Delfosse, X.; Allard, F.; Homeier, D.; Malo, L.; Morley, C.; Naud, M. E.; Bonnefoy, M.

2017-06-01

Aims: We conducted a multi-wavelength, multi-instrument observational characterisation of the candidate free-floating planet CFBDSIR J214947.2-040308.9, a late T-dwarf with possible low-gravity features, in order to constrain its physical properties. Methods: We analysed nine hours of X-shooter spectroscopy with signal detectable from 0.8 to 2.3 μm, as well as additional photometry in the mid-infrared using the Spitzer Space Telescope. Combined with a VLT/HAWK-I astrometric parallax, this enabled a full characterisation of the absolute flux from the visible to 5 μm, encompassing more than 90% of the expected energy emitted by such a cool late T-type object. Our analysis of the spectrum also provided the radial velocity and therefore the determination of its full 3D kinematics. Results: While our new spectrum confirms the low gravity and/or high metallicity of CFBDSIR 2149, the parallax and kinematics safely rule out membership to any known young moving group, including AB Doradus. We use the equivalent width of the K I doublet at 1.25 μm as a promising tool to discriminate the effects of low-gravity from the effects of high-metallicity on the emission spectra of cool atmospheres. In the case of CFBDSIR 2149, the observed K I doublet clearly favours the low-gravity solution. Conclusions: CFBDSIR 2149 is therefore a peculiar late-T dwarf that is probably a young, planetary-mass object (2-13 MJup, <500 Myr) possibly similar to the exoplanet 51 Eri b, or perhaps a 2-40 MJup brown dwarf with super-solar metallicity. Based on observations obtained with X-shooter on VLT-UT2 at ESO-Paranal (run 091.D-0723). Based on observations obtained with HAWKI on VLT-UT4 (run 089.C-0952, 090.C-0483, 091.C-0543,092.C-0548,293.C-5019(A) and run 086.C-0655(A)). Based on observations obtained with ISAAC on VLT-UT3 at ESO-Paranal (run 290.C-5083). Based on observation obtained with WIRCam at CFHT (program 2012BF12). Based on Spitzer Space telescope DDT observation (program 10166).

Banyan. X. Discovery of a Wide, Low-gravity L-type Companion to a Fast-rotating M3 Dwarf

NASA Astrophysics Data System (ADS)

Desrochers, Marie-Eve; Artigau, Étienne; Gagné, Jonathan; Doyon, René; Malo, Lison; Faherty, Jacqueline K.; Lafrenière, David

2018-01-01

We report the discovery of a substellar-mass co-moving companion to 2MASS J22501512+2325342, an M3 candidate member of the young (130–200 Myr) AB Doradus Moving Group (ABDMG). This L3 β companion was discovered in a 2MASS search for companions at separations of 3″–18″ from a list of 2812 stars suspected to be young (≲500 Myr) in the literature, and was confirmed with follow-up astrometry and spectroscopy. Evolutionary models yield a companion mass of {30}-4+11 {M}{Jup} at the age of ABDMG. The 2MASS J22501512+2325342 AB system appears to be a spatial outlier to the bulk of ABDMG members, similarly to the young 2MASS J22362452+4751425 AB system. Future searches for young objects around these two systems would make it possible to determine whether they are part of a spatial extension of the known ABDMG distribution. Based on observations obtained at the Canada–France–Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientique of France, and the University of Hawaii.

Detection et caracterisation de naines brunes et exoplanetes avec un filtre accordable pour applications dans l'espace

NASA Astrophysics Data System (ADS)

Ingraham, Patrick Jon

This thesis determines the capability of detecting faint companions in the presence of speckle noise when performing space-based high-contrast imaging through spectral differential imagery (SDI) using a low-order Fabry-Perot etalon as a tunable filter. The performance of such a tunable filter is illustrated through the Tunable Filter Imager (TFI), an instrument designed for the James Webb Space Telescope (JWST). Using a TFI prototype etalon and a custom designed test bed, the etalon's ability to perform speckle-suppression through SDI is demonstrated experimentally. Improvements in contrast vary with separation, ranging from a factor of ˜10 at working angles greater than 11 lambda/D and increasing up to a factor of ˜60 at 5 lambda/D. These measurements are consistent with a Fresnel optical propagation model which shows the speckle suppression capability is limited by the test bed and not the etalon. This result demonstrates that a tunable filter is an attractive option to perform high-contrast imaging through SDI. To explore the capability of space-based SDI using an etalon, we perform an end-to-end Fresnel propagation of JWST and TFI. Using this simulation, a contrast improvement ranging from a factor of ˜7 to ˜100 is predicted, depending on the instrument's configuration. The performance of roll-subtraction is simulated and compared to that of SDI. The SDI capability of the Near-Infrared Imager and Slitless Spectrograph (NIRISS), the science instrument module to replace TFI in the JWST Fine Guidance Sensor is also determined. Using low resolution, multi-band (0.85-2.4 microm) multi-object spectroscopy, 104 objects towards the central region of the Orion Nebular Cluster have been assigned spectral types including 7 new brown dwarfs, and 4 new planetary mass candidates. These objects are useful for determining the substellar initial mass function and for testing evolutionary and atmospheric models of young stellar and substellar objects. Using the measured H

Suzaku Observation of Strong Fluorescent Iron Line Emission from the Young Stellar Object V1647 Ori during Its New X-ray Outburst

NASA Technical Reports Server (NTRS)

Hamaguchi, Kenji; Grosso, Nicolas; Kastner, Joel H.; Weintraub, David A.; Richmond, Michael

2009-01-01

The Suzaku X-ray satellite observed the young stellar object V1647 Ori on 2008 October 8 during the new mass accretion outburst reported in August 2008. During the 87 ksec observation with a net exposure of 40 ks, V1647 Ori showed a. high level of X-ray emission with a gradual decrease in flux by a factor of 5 and then displayed an abrupt flux increase by an order of magnitude. Such enhanced X-ray variability was also seen in XMM-Newton observations in 2004 and 2005 during the 2003-2005 outburst, but has rarely been observed for other young stellar objects. The spectrum clearly displays emission from Helium-like iron, which is a signature of hot plasma (kT approx.5 keV). It also shows a fluorescent iron Ka line with a remarkably large equivalent width of approx. 600 eV. Such a, large equivalent width indicates that a part of the incident X-ray emission that irradiates the circumstellar material and/or the stellar surface is hidden from our line of sight. XMM-Newton spectra during the 2003-2005 outburst did not show a strong fluorescent iron Ka line ; so that the structure of the circumstellar gas very close to the stellar core that absorbs and re-emits X-ray emission from the central object may have changed in between 2005 and 2008. This phenomenon may be related to changes in the infrared morphology of McNeil's nebula between 2004 and 2008.

Developments in Young Infants' Reasoning about Occluded Objects

ERIC Educational Resources Information Center

Aguiar, Andrea; Baillargeon, Renee

2002-01-01

Eight experiments were conducted to examine 3- and 3.5-month-old infants' responses to occlusion events. The results revealed two developments, one in infants' knowledge of when objects should and should not be occluded and the other in infants' ability to posit additional objects to make sense of events that would otherwise violate their…

VizieR Online Data Catalog: The Auriga-California molecular cloud (Broekhoven-Fiene+, 2014)

NASA Astrophysics Data System (ADS)

Broekhoven-Fiene, H.; Matthews, B. C.; Harvey, P. M.; Gutermuth, R. A.; Huard, T. L.; Tothill, N. F. H.; Nutter, D.; Bourke, T. L.; Difrancesco, J.; Jorgensen, J. K.; Allen, L. E.; Chapman, N. L.; Cieza, L. A.; Dunham, M. M.; Merin, B.; Miller, J. F.; Terebey, S.; Peterson, D. E.; Stapelfeldt, K. R.

2017-06-01

We have mapped a significant fraction of the AMC with the Infrared Array Camera (IRAC; Fazio et al. 2004ApJS..154...10F) and the Mid-Infrared Photometer for Spitzer (MIPS; Rieke et al. 2004ApJS..154...25R) on board the Spitzer Space Telescope (Werner et al. 2004ApJS..154....1W), with a total overlapping coverage of 2.5 deg2 in the four IRAC bands (3.6, 4.5, 5.8 and 8.0 um) and 10.47 deg2 in the three MIPS bands (24, 70, and 160 um). The mapped areas are not all contiguous and were chosen to include the areas with AV>3, as given by the Dobashi et al. (2005PASJ...57....1S) extinction maps. The goal of these observations is to identify and characterize the young stellar object (YSO) and substellar object populations. The data presented here are the first mid-IR census of the YSO population in this region. (4 data files).

A Theoretical Model of X-Ray Jets from Young Stellar Objects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takasao, Shinsuke; Suzuki, Takeru K.; Shibata, Kazunari, E-mail: takasao@kwasan.kyoto-u.ac.jp

There is a subclass of X-ray jets from young stellar objects that are heated very close to the footpoint of the jets, particularly DG Tau jets. Previous models have attributed the strong heating to shocks in the jets. However, the mechanism that localizes the heating at the footpoint remains puzzling. We presented a different model of such X-ray jets, in which the disk atmosphere is magnetically heated. Our disk corona model is based on the so-called nanoflare model for the solar corona. We show that the magnetic heating near the disks can result in the formation of a hot coronamore » with a temperature of ≳10{sup 6} K, even if the average field strength in the disk is moderately weak, ≳1 G. We determine the density and the temperature at the jet base by considering the energy balance between the heating and cooling. We derive the scaling relations of the mass-loss rate and terminal velocity of jets. Our model is applied to the DG Tau jets. The observed temperature and estimated mass-loss rate are consistent with the prediction of our model in the case of a disk magnetic field strength of ∼20 G and a heating region of <0.1 au. The derived scaling relation of the temperature of X-ray jets could be a useful tool for estimating the magnetic field strength. We also find that the jet X-ray can have a significant impact on the ionization degree near the disk surface and the dead zone size.« less

X-shooter spectroscopy of young stellar objects in Lupus. Atmospheric parameters, membership, and activity diagnostics

NASA Astrophysics Data System (ADS)

Frasca, A.; Biazzo, K.; Alcalá, J. M.; Manara, C. F.; Stelzer, B.; Covino, E.; Antoniucci, S.

2017-06-01

Aims: A homogeneous determination of basic stellar parameters of young stellar object (YSO) candidates is needed to confirm their pre-main sequence evolutionary stage and membership to star forming regions (SFRs), and to get reliable values of the quantities related to chromospheric activity and accretion. Methods: We used the code ROTFIT and synthetic BT-Settl spectra for the determination of the atmospheric parameters (Teff and log g), veiling (r), radial (RV), and projected rotational velocity (vsini) from X-shooter spectra of 102 YSO candidates (95 of infrared Class II and seven Class III) in the Lupus SFR. The spectral subtraction of inactive templates, rotationally broadened to match the vsini of the targets, enabled us to measure the line fluxes for several diagnostics of both chromospheric activity and accretion, such as Hα, Hβ, Ca II, and Na I lines. Results: We have shown that 13 candidates can be rejected as Lupus members based on their discrepant RV with respect to Lupus and/or the very low log g values. At least 11 of them are background giants, two of which turned out to be lithium-rich giants. Regarding the members, we found that all Class III sources have Hα fluxes that are compatible with a pure chromospheric activity, while objects with disks lie mostly above the boundary between chromospheres and accretion. Young stellar objects with transitional disks display both high and low Hα fluxes. We found that the line fluxes per unit surface are tightly correlated with the accretion luminosity (Lacc) derived from the Balmer continuum excess. This rules out that the relationships between Lacc and line luminosities found in previous works are simply due to calibration effects. We also found that the Ca II-IRT flux ratio, FCaII8542/FCaII8498, is always small, indicating an optically thick emission source. The latter can be identified with the accretion shock near the stellar photosphere. The Balmer decrement reaches instead, for several accretors, high

Parts and Relations in Young Children's Shape-Based Object Recognition

ERIC Educational Resources Information Center

Augustine, Elaine; Smith, Linda B.; Jones, Susan S.

2011-01-01

The ability to recognize common objects from sparse information about geometric shape emerges during the same period in which children learn object names and object categories. Hummel and Biederman's (1992) theory of object recognition proposes that the geometric shapes of objects have two components--geometric volumes representing major object…

Sex-related preferences for real and doll faces versus real and toy objects in young infants and adults.

PubMed

Escudero, Paola; Robbins, Rachel A; Johnson, Scott P

2013-10-01

Findings of previous studies demonstrate sex-related preferences for toys in 6-month-old infants; boys prefer nonsocial or mechanical toys such as cars, whereas girls prefer social toys such as dolls. Here, we explored the innate versus learned nature of this sex-related preferences using multiple pictures of doll and real faces (of men and women) as well as pictures of toy and real objects (cars and stoves). In total, 48 4- and 5-month-old infants (24 girls and 24 boys) and 48 young adults (24 women and 24 men) saw six trials of all relevant pairs of faces and objects, with each trial containing a different exemplar of a stimulus type. The infant results showed no sex-related preferences; infants preferred faces of men and women regardless of whether they were real or doll faces. Similarly, adults did not show sex-related preferences for social versus nonsocial stimuli, but unlike infants they preferred faces of the opposite sex over objects. These results challenge claims of an innate basis for sex-related preferences for toy real stimuli and suggest that sex-related preferences result from maturational and social development that continues into adulthood. Copyright © 2013 Elsevier Inc. All rights reserved.

The GAPS Programme with HARPS-N at TNG. XV. A substellar companion around a K giant star identified with quasi-simultaneous HARPS-N and GIANO measurements

NASA Astrophysics Data System (ADS)

González-Álvarez, E.; Affer, L.; Micela, G.; Maldonado, J.; Carleo, I.; Damasso, M.; D'Orazi, V.; Lanza, A. F.; Biazzo, K.; Poretti, E.; Gratton, R.; Sozzetti, A.; Desidera, S.; Sanna, N.; Harutyunyan, A.; Massi, F.; Oliva, E.; Claudi, R.; Cosentino, R.; Covino, E.; Maggio, A.; Masiero, S.; Molinari, E.; Pagano, I.; Piotto, G.; Smareglia, R.; Benatti, S.; Bonomo, A. S.; Borsa, F.; Esposito, M.; Giacobbe, P.; Malavolta, L.; Martinez-Fiorenzano, A.; Nascimbeni, V.; Pedani, M.; Rainer, M.; Scandariato, G.

2017-10-01

Context. Identification of planetary companions of giant stars is made difficult because of the astrophysical noise, that may produce radial velocity variations similar to those induced by a companion. On the other hand any stellar signal is wavelength dependent, while signals due to a companion are achromatic. Aims: Our goal is to determine the origin of the Doppler periodic variations observed in the thick disk K giant star TYC 4282-605-1 by HARPS-N at the Telescopio Nazionale Galileo (TNG) and verify if they can be due to the presence of a substellar companion. Methods: Several methods have been used to exclude the stellar origin of the observed signal including detailed analysis of activity indicators and bisector and the analysis of the photometric light curve. Finally we have conducted an observational campaign to monitor the near infrared (NIR) radial velocity with GIANO at the TNG in order to verify whether the NIR amplitude variations are comparable with those observed in the visible. Results: Both optical and NIR radial velocities show consistent variations with a period at 101 days and similar amplitude, pointing to the presence of a companion orbiting the target. The main orbital properties obtained for our giant star with a derived mass of M = 0.97 ± 0.03M⊙ are MPsini = 10.78 ± 0.12MJ; P = 101.54 ± 0.05 days; e = 0.28 ± 0.01 and a = 0.422 ± 0.009 AU. The chemical analysis shows a significant enrichment in the abundance of Na I, Mg I, Al I and Si I while the rest of analyzed elements are consistent with the solar value demonstrating that the chemical composition corresponds with an old K giant (age = 10.1 Gyr) belonging to local thick disk. Conclusions: We conclude that the substellar companion hypothesis for this K giant is the best explanation for the observed periodic radial velocity variation. This study also shows the high potential of multi-wavelength radial velocity observations for the validation of planet candidates. Based on

Curriculum for Young Deaf Children.

ERIC Educational Resources Information Center

Restaino, Lillian C. R.; And Others

Presented is a curriculum designed to provide the teacher of the young deaf child with learning disabilities with a description of developmental objectives and methods for fulfilling these objectives in the areas of gross motor development, sensory motor integration, visual analysis, attention and memory, and conceptualization. The objectives are…

The Unevenly Distributed Nearest Brown Dwarfs

NASA Astrophysics Data System (ADS)

Bihain, Gabriel; Scholz, Ralf-Dieter

2016-08-01

To address the questions of how many brown dwarfs there are in the Milky Way, how do these objects relate to star formation, and whether the brown dwarf formation rate was different in the past, the star-to-brown dwarf number ratio can be considered. While main sequence stars are well known components of the solar neighborhood, lower mass, substellar objects increasingly add to the census of the nearest objects. The sky projection of the known objects at <6.5 pc shows that stars present a uniform distribution and brown dwarfs a non-uniform distribution, with about four times more brown dwarfs behind than ahead of the Sun relative to the direction of rotation of the Galaxy. Assuming that substellar objects distribute uniformly, their observed configuration has a probability of 0.1 %. The helio- and geocentricity of the configuration suggests that it probably results from an observational bias, which if compensated for by future discoveries, would bring the star-to-brown dwarf ratio in agreement with the average ratio found in star forming regions.

Sex-related preferences for real and doll’s faces versus real and toy objects in young infants and adults

PubMed Central

Escudero, Paola; Robbins, Rachel A.; Johnson, Scott P.

2013-01-01

Findings of previous studies demonstrate sex-related preferences for toys in 6-month-old infants: Boys prefer non-social or mechanical toys such as cars, while girls prefer social toys such as dolls. Here, we explored the innate versus learned nature of this sex-related preferences using multiple pictures of doll and real faces (of men and women) as well as pictures of toy and real objects (cars and stoves). Forty-eight 4- and 5-month-old infants (24 girls) and 48 young adults (24 women) saw six trials of all relevant pairs of faces and objects, with each trial containing a different exemplar of a stimulus type. The infant results showed no sex-related preferences; infants preferred faces of men and women, regardless of whether they were real or doll’s faces. Similarly, adults did not show sex-related preferences for social versus non-social stimuli, but, unlike infants, they preferred faces of the opposite sex over objects. These results challenge claims of an innate basis for sex-related preferences for toy and real stimuli preferences (Connellan et al., 2000) and suggest that sex-related preferences result from maturational and social development, which continues into adulthood. PMID:23933180

Ape Metaphysics: Object Individuation without Language

ERIC Educational Resources Information Center

Mendes, Natacha; Rakoczy, Hannes; Call, Josep

2008-01-01

Developmental research suggests that whereas very young infants individuate objects purely on spatiotemporal grounds, from (at latest) around 1 year of age children are capable of individuating objects according to the kind they belong to and the properties they instantiate. As the latter ability has been found to correlate with language, some…

Visual Object Pattern Separation Varies in Older Adults

ERIC Educational Resources Information Center

Holden, Heather M.; Toner, Chelsea; Pirogovsky, Eva; Kirwan, C. Brock; Gilbert, Paul E.

2013-01-01

Young and nondemented older adults completed a visual object continuous recognition memory task in which some stimuli (lures) were similar but not identical to previously presented objects. The lures were hypothesized to result in increased interference and increased pattern separation demand. To examine variability in object pattern separation…

A full 1---40 micron spectral energy distribution for the Becklin-Neugebauer object: Placing constraints on disk size for a runaway massive young stellar object

NASA Astrophysics Data System (ADS)

Shuping, Ralph; Keller, Luke D.; Adams, Joseph D.; Petkova, Maya; Wood, Kenneth; Herter, Terry; Sloan, Greg; Jaffe, Daniel Thomas; Greene, Thomas P.; Ennico, Kimberly

2017-01-01

The Becklin-Neugebauer (BN) Object—one of the brightest infrared obejcts in the sky—is a highly luminous young stellar object (YSO) deeply embedded in Orion Molecular Cloud 1 (OMC-1), which sits behind the Orion Nebula (M42). The BN object is likely a 8—15 M⊙ star and has no obvious optical counterpart due to high visual extinction on the line of sight. Furthermore, recent radio studies show that BN is moving towards the northwest at approximately 26 km/s with respect to the Orion Nebula Cluster (ONC), which may indicate that BN was dynamically ejected from either the Trapezium or from within OMC-1 itself. Near-IR polarimetry suggests that BN is surrounded by a large (R=800 AU) disk, which is surprising since a close encounter leading to an ejection would likely disrupt and/or truncate a disk of this size. In this poster presentation, we present new SOFIA-FORCAST grism spectroscopy of BN from 10—40 μm. In conjunction with previous SOFIA-FORCAST photometry and data form the literature, we present the full 1—40 μm SED of BN which we compare to theoretical models using the HOCHUNK-3D radiative equilibrium code. We report constraints on disk parameters and discuss implications for dynamical ejection scenarios.

The optical + infrared L dwarf spectral sequence of young planetary-mass objects in the Upper Scorpius association

NASA Astrophysics Data System (ADS)

Lodieu, N.; Zapatero Osorio, M. R.; Béjar, V. J. S.; Peña Ramírez, K.

2018-01-01

We present the results of photometric and spectroscopic follow-ups of the lowest mass member candidates in the nearest OB association, Upper Scorpius (∼5-10 Myr; 145 ± 17 pc), with the Gran Telescopio de Canarias (GTC) and European Southern Observatory (ESO) Very Large Telescope (VLT). We confirm the membership of the large majority (>80 per cent) of candidates originally selected photometrically and astrometrically based on their spectroscopic features, weak equivalent widths of gravity-sensitive doublets and radial velocities. Confirmed members follow a sequence over a wide magnitude range (J = 17.0-19.3 mag) in several colour-magnitude diagrams with optical, near- and mid-infrared photometry and have near-infrared spectral types in the L1-L7 interval with likely masses below 15 Jupiter masses. We find that optical spectral types tend to be earlier than near-infrared spectral types by a few subclasses for spectral types later than M9. We investigate the behaviour of spectral indices, defined in the literature as a function of spectral type and gravity, by comparison with values reported in the literature for young and old dwarfs. We also derive effective temperatures in the 1900-1600 K range from fits of synthetic model-atmosphere spectra to the observed photometry, but we caution that the procedure carries large uncertainties. We determine bolometric corrections for young L dwarfs with ages of ∼5-10 Myr (Upper Sco association) and find them to be similar in the J band but larger by 0.1-0.4 mag in the K band with respect to field L dwarfs. Finally, we discover two faint young L dwarfs, Visible and Infrared Survey Telescope for Astronomy (VISTA) J1607-2146 (L4.5) and VISTA J1611-2215 (L5), that have Hα emission and possible flux excesses at 4.5 μm, pointing to the presence of accretion from a disc on to the central objects of mass below ∼15MJup at an age of 5-10 Myr.

Actions Versus Likenesses As Determinants of Early Object Concepts.

ERIC Educational Resources Information Center

Latimer, James

This experiment was designed to test whether paired objects described as interacting through movement are more memorable to young children than the same objects described as alike in structure or color. Drawings of eight familiar objects were presented in unfamiliar combinations to forty-five 4-year-old subjects. Objects were described as…

A Spectroscopic Study of Young Stellar Objects in the Serpens Cloud Core and NGC 1333

NASA Astrophysics Data System (ADS)

Winston, E.; Megeath, S. T.; Wolk, S. J.; Hernandez, J.; Gutermuth, R.; Muzerolle, J.; Hora, J. L.; Covey, K.; Allen, L. E.; Spitzbart, B.; Peterson, D.; Myers, P.; Fazio, G. G.

2009-06-01

We present spectral observations of 130 young stellar objects (YSOs) in the Serpens Cloud Core and NGC 1333 embedded clusters. The observations consist of near-IR spectra in the H and K bands from SpeX on the IRTF and far-red spectra (6000-9000 Å) from Hectospec on the Multi-Mirror Telescope. These YSOs were identified in previous Spitzer and Chandra observations, and the evolutionary classes of the YSOs were determined from the Spitzer mid-IR photometry. With these spectra we search for corroborating evidence for the pre-main-sequence nature of the objects, study the properties of the detected emission lines as a function of evolutionary class, and obtain spectral types for the observed YSOs. The temperatures implied by the spectral types are combined with luminosities determined from the near-IR photometry to construct Hertzsprung-Russell (H-R) diagrams for the clusters. By comparing the positions of the YSOs in the H-R diagrams with the pre-main-sequence tracks of Baraffe (1998), we determine the ages of the embedded sources and study the relative ages of the YSOs with and without optically thick circumstellar disks. The apparent isochronal ages of the YSOs in both clusters range from less than 1 Myr to 10 Myr, with most objects below 3 Myr. The observed distributions of ages for the Class II and Class III objects are statistically indistinguishable. We examine the spatial distribution and extinction of the YSOs as a function of their isochronal ages. We find the sources <3 Myr to be concentrated in the molecular cloud gas, while the older sources are spatially dispersed and are not deeply embedded. Nonetheless, the sources with isochronal ages >3 Myr show all the characteristics of YSOs in their spectra, their IR spectral energy distributions, and their X-ray emission; we find no evidence that they are contaminating background giants or foreground dwarfs. However, we find no corresponding decrease in the fraction of sources with infrared excess with isochronal

Cosmic-Ray Propagation in Turbulent Spiral Magnetic Fields Associated with Young Stellar Objects

NASA Astrophysics Data System (ADS)

Fatuzzo, Marco; Adams, Fred C.

2018-04-01

External cosmic rays impinging upon circumstellar disks associated with young stellar objects provide an important source of ionization, and, as such, play an important role in disk evolution and planet formation. However, these incoming cosmic rays are affected by a variety of physical processes internal to stellar/disk systems, including modulation by turbulent magnetic fields. Globally, these fields naturally provide both a funneling effect, where cosmic rays from larger volumes are focused into the disk region, and a magnetic mirroring effect, where cosmic rays are repelled due to the increasing field strength. This paper considers cosmic-ray propagation in the presence of a turbulent spiral magnetic field, analogous to that produced by the solar wind. The interaction of this wind with the interstellar medium defines a transition radius, analogous to the heliopause, which provides the outer boundary to this problem. We construct a new coordinate system where one coordinate follows the spiral magnetic field lines and consider magnetic perturbations to the field in the perpendicular directions. The presence of magnetic turbulence replaces the mirroring points with a distribution of values and moves the mean location outward. Our results thus help quantify the degree to which cosmic-ray fluxes are reduced in circumstellar disks by the presence of magnetic field structures that are shaped by stellar winds. The new coordinate system constructed herein should also be useful in other astronomical applications.

Objectively measured physical activity and sedentary-time are associated with arterial stiffness in Brazilian young adults.

PubMed

Horta, Bernardo Lessa; Schaan, Beatriz D; Bielemann, Renata Moraes; Vianna, Carolina Ávila; Gigante, Denise Petrucci; Barros, Fernando C; Ekelund, Ulf; Hallal, Pedro Curi

2015-11-01

To examine the associations between objectively measured physical activity and sedentary time with pulse wave velocity (PWV) in Brazilian young adults. Cross-sectional analysis with participants of the 1982 Pelotas (Brazil) Birth Cohort who were followed-up from birth to 30 years of age. Overall physical activity (PA) assessed as the average acceleration (mg), time spent in moderate-to-vigorous physical activity (MVPA - min/day) and sedentary time (min/day) were calculated from acceleration data. Carotid-femoral PWV (m/s) was assessed using a portable ultrasound. Systolic and diastolic blood pressure (SBP/DBP), waist circumference (WC) and body mass index (BMI) were analyzed as possible mediators. Multiple linear regression and g-computation formula were used in the analyses. Complete data were available for 1241 individuals. PWV was significantly lower in the two highest quartiles of overall PA (0.26 m/s) compared with the lowest quartile. Participants in the highest quartile of sedentary time had 0.39 m/s higher PWV (95%CI: 0.20; 0.57) than those in the lowest quartile. Individuals achieving ≥30 min/day in MVPA had lower PWV (β = -0.35; 95%CI: -0.56; -0.14). Mutually adjusted analyses between MVPA and sedentary time and PWV changed the coefficients, although results from sedentary time remained more consistent. WC captured 44% of the association between MVPA and PWV. DBP explained 46% of the association between acceleration and PWV. Physical activity was inversely related to PWV in young adults, whereas sedentary time was positively associated. Such associations were only partially mediated by WC and DBP. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Young drivers' responses to anti-speeding advertisements: Comparison of self-report and objective measures of persuasive processing and outcomes.

PubMed

Kaye, Sherrie-Anne; Lewis, Ioni; Algie, Jennifer; White, Melanie J

2016-05-18

Self-report measures are typically used to assess the effectiveness of road safety advertisements. However, psychophysiological measures of persuasive processing (i.e., skin conductance response [SCR]) and objective driving measures of persuasive outcomes (i.e., in-vehicle Global Positioning System [GPS] devices) may provide further insights into the effectiveness of these advertisements. This study aimed to explore the persuasive processing and outcomes of 2 anti-speeding advertisements by incorporating both self-report and objective measures of speeding behavior. In addition, this study aimed to compare the findings derived from these different measurement approaches. Young drivers (N = 20, M age = 21.01 years) viewed either a positive or negative emotion-based anti-speeding television advertisement. While viewing the advertisement, SCR activity was measured to assess ad-evoked arousal responses. The RoadScout GPS device was then installed in participants' vehicles for 1 week to measure on-road speed-related driving behavior. Self-report measures assessed persuasive processing (emotional and arousal responses) and actual driving behavior. There was general correspondence between the self-report measures of arousal and the SCR and between the self-report measure of actual driving behavior and the objective driving data (as assessed via the GPS devices). This study provides insights into how psychophysiological and GPS devices could be used as objective measures in conjunction with self-report measures to further understand the persuasive processes and outcomes of emotion-based anti-speeding advertisements.

Objectively-assessed physical activity and weight change in young adults: a randomized controlled trial.

PubMed

Unick, Jessica L; Lang, Wei; Williams, Samantha E; Bond, Dale S; Egan, Caitlin M; Espeland, Mark A; Wing, Rena R; Tate, Deborah F

2017-12-04

Reductions in physical activity (PA) are common throughout young adulthood and low PA is associated with weight gain. The SNAP Trial previously reported that two self-regulation approaches to weight gain prevention reduced weight gain over a 2-year period in 18-35 year olds. Presented here are secondary analyses examining changes in PA and the relationship between PA and weight change over 2 years. 599 young adults (age: 27.4 ± 4.4 yrs.; BMI: 25.4 ± 2.6 kg/m 2 ) were randomly assigned to 1 of 3 treatment arms: Small Changes (reduce calorie intake by 100 kcals/day & add 2000 steps/day), Large Changes (lose 2.3-4.5 kg initially & increase PA to ≥250 min/wk), or Self-guided (control condition). Small and Large Changes received 10, face-to-face group sessions (months 1-4), and two 4-week refresher courses each subsequent year. Body weight and PA were objectively-measured at baseline, 4 months, 1 and 2 years. Daily steps and bout-related moderate-to-vigorous intensity PA (MVPA: ≥3 METs, ≥10-min bouts) was calculated. Changes in bout-related MVPA and daily steps did not differ among treatment groups over the 2-year period (p's > 0.16). Collapsed across groups, participants gaining >1 lb. (n = 187; 39.6%) had smaller changes in bout-related MVPA at 4 months, 1 and 2 years relative to those maintaining or losing weight (≤1 lb. weight gain; n = 282, 60.4%, p's < 0.05). Averaged across time points, this difference equated to 47.8 min/week. Those gaining and not gaining >1 lb. did not differ on daily steps (p's > 0.10). Among participants engaging in ≥250 min/wk. of MVPA at 2 years (n = 181), 30% gained >1 lb. from baseline to 2 years, which was not different from those engaging in 150-250 min/wk. (n = 87; 36%; p = 0.40), but this percentage was significantly lower when compared to those engaging in <150 min/wk. (n = 176; 49%; p < 0.001). On average, PA differences were not observed between young

First Keck Nulling Observations of a Young Stellar Object: Probing the Circumstellar Environment of the Herbig Ae star MWC 325

NASA Technical Reports Server (NTRS)

Ragland, S.; Ohnaka, K.; Hillenbrand, L.; Ridgway, S. T.; Colavita, M. M.; Akeson, R. L.; Cotton, W.; Danichi, W. C.; Hrynevych, M.; Milan-Gabet, R.;

Naming Speed of Adolescents and Young Adults with Attention Deficit Hyperactivity Disorder: Differences in Alphanumeric Versus Color/Object Naming.

PubMed

Whipple, Brittany D; Nelson, Jason M

2016-02-01

This study investigated the performance of adolescents and young adults with Attention Deficit Hyperactivity Disorder (ADHD), Reading Disorder (RD), and ADHD/RD on measures of alphanumeric and nonalphanumeric naming speed and the relationship between naming speed and academic achievement. The sample (N = 203) included students aged 17-28 years diagnosed with ADHD (n = 83), RD (n = 71), or ADHD/RD (n = 49). Individuals with ADHD performed significantly faster on measures of alphanumeric naming compared with RD and comorbid groups and, within group, demonstrated significantly quicker naming of letters/digits compared with colors/objects. Both alphanumeric rapid naming scores and processing speed scores variably predicted academic achievement scores across groups, whereas nonalphanumeric rapid naming only predicted reading comprehension scores within the ADHD group. Results support findings that older individuals with ADHD show relative weakness in rapid naming of objects and colors. Implications of these findings in regard to assessment of older individuals for ADHD are discussed. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Motion and Edge Sensitivity in Perception of Object Unity

ERIC Educational Resources Information Center

Smith, W. Carter; Johnson, Scott P.; Spelke, Elizabeth S.

2003-01-01

Although much evidence indicates that young infants perceive unitary objects by analyzing patterns of motion, infants' abilities to perceive object unity by analyzing Gestalt properties and by integrating distinct views of an object over time are in dispute. To address these controversies, four experiments investigated adults' and infants'…

Object Boundaries Influence Toddlers' Performance in a Search Task

ERIC Educational Resources Information Center

Shutts, Kristin; Keen, Rachel; Spelke, Elizabeth S.

2006-01-01

Previous research has shown that young children have difficulty searching for a hidden object whose location depends on the position of a partly visible physical barrier. Across four experiments, we tested whether children's search errors are affected by two variables that influence adults' object-directed attention: object boundaries and…

The slow ionized wind and rotating disklike system that are associated with the high-mass young stellar object G345.4938+01.4677

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guzmán, Andrés E.; Garay, Guido; Bronfman, Leonardo

2014-12-01

We report the detection, made using ALMA, of the 92 GHz continuum and hydrogen recombination lines (HRLs) H40α, H42α, and H50β emission toward the ionized wind associated with the high-mass young stellar object G345.4938+01.4677. This is the luminous central dominating source located in the massive and dense molecular clump associated with IRAS 16562–3959. The HRLs exhibit Voigt profiles, which is a strong signature of Stark broadening. We successfully reproduce the observed continuum and HRLs simultaneously using a simple model of a slow ionized wind in local thermodynamic equilibrium, with no need for a high-velocity component. The Lorentzian line wings implymore » electron densities of 5 × 10{sup 7} cm{sup –3} on average. In addition, we detect SO and SO{sub 2} emission arising from a compact (∼3000 AU) molecular core associated with the central young star. The molecular core exhibits a velocity gradient that is perpendicular to the jet-axis, which we interpret as evidence of rotation. The set of observations toward G345.4938+01.4677 are consistent with it being a young high-mass star associated with a slow photo-ionized wind.« less

Object-Based Epistemology at a Creationist Museum

NASA Astrophysics Data System (ADS)

Wendel, Paul J.

2011-01-01

In a regional young-earth creationist museum, objects are presented as if they speak for themselves, purportedly embodying proof that the earth is less than 10,000 years old, that humans have lived on earth throughout its history, and that dinosaurs and humans lived simultaneously. In public lectures, tours, and displays, museum associates emphasize direct observation over inference or theory. These emphases resonate closely with the "object-based epistemology" of the late nineteenth century described in Steven Conn's Museums and American Intellectual Life, 1876- 1926. In Conn's description, museum objects, artfully arranged and displayed, were intended to speak for themselves, and observation and categorization were valued over experiment and theory. The regional young-earth creationist museum is observed to partly succeed and partly fail in implementing an object-based epistemology. Although object-based epistemology represents a nineteenth-century approach to knowledge and museum display, it is compatible with an inductive approach to biblical interpretation and it confers various rhetorical advantages to creationist arguments. It is concluded that a focus on the theory-laden nature of data would likely strengthen nature-of-science education efforts to increase public acceptance of evolution.

NEW YOUNG STAR CANDIDATES IN CG4 AND Sa101

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rebull, L. M.; Laine, S.; Laher, R.

2011-07-15

The CG4 and Sa101 regions together cover a region of {approx}0.5 deg{sup 2} in the vicinity of a 'cometary globule' that is part of the Gum Nebula. There are seven previously identified young stars in this region; we have searched for new young stars using mid- and far-infrared data (3.6-70 {mu}m) from the Spitzer Space Telescope, combined with ground-based optical data and near-infrared data from the Two Micron All Sky Survey. We find infrared excesses in all six of the previously identified young stars in our maps and identify 16 more candidate young stars based on apparent infrared excesses. Mostmore » (73%) of the new young stars are Class II objects. There is a tighter grouping of young stars and young star candidates in the Sa101 region, in contrast to the CG4 region, where there are fewer young stars and young star candidates, and they are more dispersed. Few likely young objects are found in the 'fingers' of the dust being disturbed by the ionization front from the heart of the Gum Nebula.« less

Weather and Rotation on Young Brown Dwarfs

NASA Astrophysics Data System (ADS)

Vos, Johanna; Biller, Beth; Allers, Katelyn; Manjavacas, Elena; Liu, Michael; Best, William; Metchev, Stanimir; Buenzli, Esther; Bonavita, Mariangela; Eriksson, Simon; Dupuy, Trent; Kopytova, Taisiya; Brandner, Wolfgang; Henning, Thomas; Bonnefoy, Mickael; Crossfield, Ian; Schlieder, Joshua; Homeier, Derek; Janson, Markus; Radigan, Jacqueline

2018-05-01

As part of a large, ground-based survey for weather patterns on exoplanet analogues, we have detected J-band variability in 5 young exoplanet analogues. We have already carried out followup Spitzer monitoring of two objects and here we propose Spitzer 3.6um and 4.5um monitoring of three early-mid-L detections in our survey. The proposed observations will enable us to assess the role of gravity in the variability properties of these young objects by providing a full measure of mid-IR amplitude across the full L spectral sequence for low-gravity objects. The proposed observations will also allow us to measure the rotational periods of our three targets. This will provide vital information on the angular momentum of young brown dwarfs, while enabling us to correct for geometric effects when considering the variability properties of our targets. This study will act as a necessary pathfinder for future variability studies of free-floating and companion exoplanets with JWST.

Spectroscopic characterization of HD 95086 b with the Gemini Planet Imager

DOE PAGES

De Rosa, Robert J.; Rameau, Julien; Patience, Jenny; ...

2016-06-21

Here, we present new H (1.5–1.8 μm) photometric and K 1 (1.9–2.2 μm) spectroscopic observations of the young exoplanet HD 95086 b obtained with the Gemini Planet Imager. The H-band magnitude has been significantly improved relative to previous measurements, whereas the low-resolution K 1 (more » $$\\lambda /\\delta \\lambda \\approx 66$$) spectrum is featureless within the measurement uncertainties and presents a monotonically increasing pseudo-continuum consistent with a cloudy atmosphere. By combining these new measurements with literature $$L^{\\prime} $$ photometry, we compare the spectral energy distribution (SED) of the planet to other young planetary-mass companions, field brown dwarfs, and to the predictions of grids of model atmospheres. HD 95086 b is over a magnitude redder in $${K}_{1}-L^{\\prime} $$ color than 2MASS J12073346–3932539 b and HR 8799 c and d, despite having a similar $$L^{\\prime} $$ magnitude. Considering only the near-infrared measurements, HD 95086 b is most analogous to the brown dwarfs 2MASS J2244316+204343 and 2MASS J21481633+4003594, both of which are thought to have dusty atmospheres. Morphologically, the SED of HD 95086 b is best fit by low temperature ($${T}_{{\\rm{eff}}}$$ = 800–1300 K), low surface gravity spectra from models which simulate high photospheric dust content. This range of effective temperatures is consistent with field L/T transition objects, but the spectral type of HD 95086 b is poorly constrained between early L and late T due to its unusual position the color–magnitude diagram, demonstrating the difficulty in spectral typing young, low surface gravity substellar objects. As one of the reddest such objects, HD 95086 b represents an important empirical benchmark against which our current understanding of the atmospheric properties of young extrasolar planets can be tested.« less

On the Distance Measurements toward Young Milky Way Objects. I. Study of IC 2944

NASA Astrophysics Data System (ADS)

Krełowski, J.; Strobel, A.; Godunova, V.; Bondar, A.

2017-12-01

We compare distances to a very young stellar aggregate, IC 2944, using three methods: direct parallaxes of Gaia, spectrophotometric parallax and our method based on intensities of interstellar CaII lines. The discrepancies between spectrophotometric distances and those, based on CaII K and H lines, were already reported. The interstellar CaII H and K lines allow one to determine both distances and radial velocities of the intervening clouds. Thus, these data allow us to check the aggregate membership. It is also possible to check the spectral classification of considered targets which is necessary for spectrophotometric parallaxes. Using three methods, we determined distances to IC 2944 stars. We demonstrate that CaII based distances agree very well with the kinematic ones but are generally much smaller than the spectrophotometric ones. We conclude that the majority of IC 2944 objects is obscured by clouds producing neutral ("gray") extinction which diminishes their brightness exactly like extended distances. This influences spectrophotometric parallaxes while those, based on the CaII lines, do not depend on extinction and this method seems to be the most reliable one inside the thin disk of our Galaxy. The Gaia trigonometric parallaxes lead to distances similar to those obtained using the CaII method if their errors are reasonably small.

Children's Exploration of Physical Phenomena during Object Play

ERIC Educational Resources Information Center

Solis, S. Lynneth; Curtis, Kaley N.; Hayes-Messinger, Amani

2017-01-01

Researchers propose that experiencing and manipulating physical principles through objects allows young children to formulate scientific intuitions that may serve as precursors to learning in STEM subjects. This may be especially true when children discover these physical principles through object affordances during play. The present study…

Near- and Mid-Infrared Photometry of the Pleiades and a New List of Substellar Candidate Members

NASA Astrophysics Data System (ADS)

Stauffer, John R.; Hartmann, Lee W.; Fazio, Giovanni G.; Allen, Lori E.; Patten, Brian M.; Lowrance, Patrick J.; Hurt, Robert L.; Rebull, Luisa M.; Cutri, Roc M.; Ramirez, Solange V.; Young, Erick T.; Rieke, George H.; Gorlova, Nadya I.; Muzerolle, James C.; Slesnick, Cathy L.; Skrutskie, Michael F.

2007-10-01

We make use of new near- and mid-IR photometry of the Pleiades cluster in order to help identify proposed cluster members. We also use the new photometry with previously published photometry to define the single-star main-sequence locus at the age of the Pleiades in a variety of color-magnitude planes. The new near- and mid-IR photometry extend effectively 2 mag deeper than the 2MASS All-Sky Point Source catalog, and hence allow us to select a new set of candidate very low-mass and substellar mass members of the Pleiades in the central square degree of the cluster. We identify 42 new candidate members fainter than Ks=14 (corresponding to 0.1 Msolar). These candidate members should eventually allow a better estimate of the cluster mass function to be made down to of order 0.04 Msolar. We also use new IRAC data, in particular the images obtained at 8 μm, in order to comment briefly on interstellar dust in and near the Pleiades. We confirm, as expected, that-with one exception-a sample of low-mass stars recently identified as having 24 μm excesses due to debris disks do not have significant excesses at IRAC wavelengths. However, evidence is also presented that several of the Pleiades high-mass stars are found to be impacting with local condensations of the molecular cloud that is passing through the Pleiades at the current epoch. This work is based (in part) on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.

Testing Envelope Models of Young Stellar Objects with Submillimeter Continuum and Molecular-Line Observations

NASA Astrophysics Data System (ADS)

Hogerheijde, Michiel R.; Sandell, Göran

2000-05-01

Theoretical models of star formation make predictions about the density and velocity structure of the envelopes surrounding isolated, low-mass young stars. This paper tests such models through high-quality submillimeter continuum imaging of four embedded young stellar objects in Taurus and previously obtained molecular-line data. Observations carried out with the Submillimeter Continuum Bolometer Array on the James Clerk Maxwell Telescope at 850 and 450 μm of L1489 IRS, L1535 IRS, L1527 IRS, and TMC 1 reveal ~2000 AU elongated structures embedded in extended envelopes. The density distribution in these envelopes is equally well fitted by a radial power-law of index p=1.0-2.0 or with a collapse model such as that of Shu. This inside-out collapse model predicts 13CO, C18O, HCO+, and H13CO+ line profiles that closely match observed spectra toward three of our four sources. This shows that the inside-out collapse model offers a good description of YSO envelopes, but also that reliable constraints on its parameters require independent measurements of the density and the velocity structure, e.g., through continuum and line observations. For the remaining source, L1489 IRS, we find that a model consisting of a 2000 AU radius, rotating, disklike structure better describes the data. Possibly, this source is in transition between the embedded class I and the optically revealed T Tauri phases. The spectral index of the dust emissivity decreases from β=1.5-2.0 in the extended envelope to 1.0+/-0.2 in the central peaks, indicating grain growth or high optical depth on small scales. The observations of L1527 IRS reveal warm (>~30 K) material outlining, and presumably heated by, its bipolar outflow. This material comprises <~0.2 Msolar, comparable to the amount of swept-up CO but only 10% of the total envelope mass. Two apparently starless cores are found at ~10,000 AU from L1489 IRS and L1535 IRS. They are cold, 10-15 K, contain 0.5-3.0 Msolar, and have flat density

ABSENCE OF SIGNIFICANT COOL DISKS IN YOUNG STELLAR OBJECTS EXHIBITING REPETITIVE OPTICAL OUTBURSTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Hauyu Baobab; Hirano, Naomi; Takami, Michihiro

2016-01-10

We report Submillimeter Array 1.3 mm high angular resolution observations toward the four EXor-type outbursting young stellar objects VY Tau, V1118 Ori, V1143 Ori, and NY Ori. The data mostly show low dust masses M{sub dust} in the associated circumstellar disks. Among the sources, NY Ori possesses a relatively massive disk with M{sub dust} ∼ 9 × 10{sup −4}M{sub ⊙}. V1118 Ori has a marginal detection equivalent to M{sub dust} ∼ 6 × 10{sup −5}M{sub ⊙}. V1143 Ori has a non-detection also equivalent to M{sub dust} < 6 × 10{sup −5}M{sub ⊙}. For the nearest source, VY Tau, we get a surprising non-detection that provides a stringent upper limit M{sub dust} < 6 × 10{sup −6}M{sub ⊙}.more » We interpret our findings as suggesting that the gas and dust reservoirs that feed the short-duration, repetitive optical outbursts seen in some EXors may be limited to the small-scale, innermost region of their circumstellar disks. This hot dust may have escaped our detection limits. Follow-up, more sensitive millimeter observations are needed to improve our understanding of the triggering mechanisms of EXor-type outbursts.« less

A Panchromatic View of Star-Forming Regions in the Magellanic Clouds: Characterizing Physical and Evolutionary Parameters of 1,000 Young Stellar Objects

NASA Astrophysics Data System (ADS)

Carlson, Lynn R.

2010-01-01

I discuss newly discovered Young Stellar Objects (YSOs) in several star-forming regions in the Magellanic Clouds. I exploit the synergy between infrared photometry from the Spitzer SAGE (Surveying the Agents of Galaxy Evolution) legacy programs, near-infrared and optical photometry from ground-based surveys, and HST imaging to characterize young stellar populations. This reveals a variety of Main Sequence Stars and Proto-Stars over a wide range of evolutionary stages. Through SED fitting, I characterize the youngest, embedded, infrared-bright YSOs. Complementary color-Magnitude analysis and isochrone fitting of optical data allows a statistical description of more evolved, unembedded stellar and protostellar populations within these same regions. I examine the early evolution of Magellanic star clusters, including propagating and triggered star formation, and take a step toward characterizing evolutionary timescales for YSOs. In this talk, I present an overview of the project and exemplify the analysis by focusing on NGC 602 in the SMC and Henize 206 in the LMC as examples. The SAGE Project is supported by NASA/Spitzer grant 1275598 and NASA NAG5-12595.

Tracing Interactions of a Protoplanet with its Circumstellar Disk

NASA Astrophysics Data System (ADS)

Stapelfeldt, Karl

2017-08-01

A candidate companion to a very young star has been discovered in HST snapshot optical images. The object is projected at the outer radius of an edge-on protoplanetary disk and is aligned with the disk plane. Keck LGS photometry results indicate the object has the same temperature as brown dwarf GQ Lupi b but with 10x less luminosity - consistent with a planetary mass companion. Because the edge-on disk suppresses the light of the central star, the companion is uniquely accessible to follow-up studies with minimal starlight residuals. We propose HST/WFC3 imaging and spectroscopy of the system to 1) fully define the morphology of the disk scattered light, particularly at the disk outer edge near the companion; 2) search for Halpha emission from the companion as evidence that it is actively accreting; and 3) complete spectral characterization of the companion using G141 spectroscopy. Confirmation of a substellar spectrum, accretion, and disk interaction action would establish this object as a leading example of an accreting protoplanet at 100 AU and offer support to models for planet formation by gravitational instability.

Preschoolers' Preparation for Retrieval in Object Relocation Tasks.

ERIC Educational Resources Information Center

Beal, Carole R.; Fleisig, Wayne E.

The finding that young children do not prepare markers to help themselves relocate objects after a delay may have resulted from children's misunderstanding of the difficulty of unassisted retrieval. This study examined children's ability to recognize that they should prepare markers in two simplified object relocation tasks after they had been…

Motivational Traits of Elite Young Soccer Players

ERIC Educational Resources Information Center

Stewart, Craig; Meyers, Michael C.

2004-01-01

Among the most overlooked aspects in the development of elite young soccer players is that of specific psychological traits. Of those traits, motivation has important implications for programs whose objectives are identification and cultivation of young, skilled performers. The growth in popularity of soccer by youth and the successes experienced…

The discovery of the peculiar L dwarf ULAS J222711-004547

NASA Astrophysics Data System (ADS)

Marocco, F.; Day-Jones, A. C.; Jones, H. R. A.; Pinfield, D. J.; Burningham, B.; Zhang, Z. H.

We present the discovery of a very peculiar L dwarf from the UKIDSS Large Area Survey (LAS), ULAS J222711-004547. Its very red infrared colours (MKO J-K = 2.79) make it the reddest brown dwarf discovered so far. The object was discovered as part of a large spectroscopic campaign aimed at constraining the sub-stellar birth rate. We obtained a moderate resolution spectrum of this target using the echelle spectrograph XSHOOTER on VLT/UT2, and classified it as L7pec, confirming its very red nature. We show that applying a simple de-reddening curve to the spectrum of ULAS J222711-004547, this becomes very similar to the spectrum of a L7 spectroscopic standard. Therefore we conclude that the reddening of the spectrum is mostly due to an excess of dust in the photosphere of the object. This new discovery joins the list of unusually red L dwarfs, whose nature is not yet fully understood, and poses a new important challenge to atmospheric modeling of substellar objects.

Teaching the Young Child: Goals for Illinois.

ERIC Educational Resources Information Center

Katz, Lilian G.

This paper, outlining the present goals, purposes and future role of the Illinois Association for the Education of Young Children (ILLAEYC), discusses what is involved in providing high quality programs for young children everywhere, not only in Illinois. Among ILLAEYC's objectives: (1) to provide a channel of information for people working with…

Abundant Methanol Ice toward a Massive Young Stellar Object in the Central Molecular Zone

NASA Astrophysics Data System (ADS)

An, Deokkeun; Sellgren, Kris; Boogert, A. C. Adwin; Ramírez, Solange V.; Pyo, Tae-Soo

2017-07-01

Previous radio observations revealed widespread gas-phase methanol (CH3OH) in the Central Molecular Zone (CMZ) at the Galactic center (GC), but its origin remains unclear. Here, we report the discovery of CH3OH ice toward a star in the CMZ, based on a Subaru 3.4-4.0 μm spectrum, aided by NASA/IRTF L\\prime imaging and 2-4 μm spectra. The star lies ˜8000 au away in projection from a massive young stellar object (MYSO). Its observed high CH3OH ice abundance (17 % +/- 3 % relative to H2O ice) suggests that the 3.535 μm CH3OH ice absorption likely arises in the MYSO’s extended envelope. However, it is also possible that CH3OH ice forms with a higher abundance in dense clouds within the CMZ, compared to within the disk. Either way, our result implies that gas-phase CH3OH in the CMZ can be largely produced by desorption from icy grains. The high solid CH3OH abundance confirms the prominent 15.4 μm shoulder absorption observed toward GC MYSOs arises from CO2 ice mixed with CH3OH. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Regulation of object recognition and object placement by ovarian sex steroid hormones

PubMed Central

Tuscher, Jennifer J.; Fortress, Ashley M.; Kim, Jaekyoon; Frick, Karyn M.

2014-01-01

The ovarian hormones 17β-estradiol (E2) and progesterone (P4) are potent modulators of hippocampal memory formation. Both hormones have been demonstrated to enhance hippocampal memory by regulating the cellular and molecular mechanisms thought to underlie memory formation. Behavioral neuroendocrinologists have increasingly used the object recognition and object placement (object location) tasks to investigate the role of E2 and P4 in regulating hippocampal memory formation in rodents. These one-trial learning tasks are ideal for studying acute effects of hormone treatments on different phases of memory because they can be administered during acquisition (pre-training), consolidation (post-training), or retrieval (pre-testing). This review synthesizes the rodent literature testing the effects of E2 and P4 on object recognition (OR) and object placement (OP), and the molecular mechanisms in the hippocampus supporting memory formation in these tasks. Some general trends emerge from the data. Among gonadally intact females, object memory tends to be best when E2 and P4 levels are elevated during the estrous cycle, pregnancy, and in middle age. In ovariectomized females, E2 given before or immediately after testing generally enhances OR and OP in young and middle-aged rats and mice, although effects are mixed in aged rodents. Effects of E2 treatment on OR 7and OP memory consolidation can be mediated by both classical estrogen receptors (ERα and ERβ), and depend on glutamate receptors (NMDA, mGluR1) and activation of numerous cell signaling cascades (e.g., ERK, PI3K/Akt, mTOR) and epigenetic processes (e.g., histone H3 acetylation, DNA methylation). Acute P4 treatment given immediately after training also enhances OR and OP in young and middle-aged ovariectomized females by activating similar cell signaling pathways as E2 (e.g., ERK, mTOR). The few studies that have administered both hormones in combination suggest that treatment can enhance OR and OP, but that

Young Stars with SALT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riedel, Adric R.; Alam, Munazza K.; Rice, Emily L.

We present a spectroscopic and kinematic analysis of 79 nearby M dwarfs in 77 systems. All of these dwarfs are low-proper-motion southern hemisphere objects and were identified in a nearby star survey with a demonstrated sensitivity to young stars. Using low-resolution optical spectroscopy from the Red Side Spectrograph on the South African Large Telescope, we have determined radial velocities, H-alpha, lithium 6708 Å, and potassium 7699 Å equivalent widths linked to age and activity, and spectral types for all of our targets. Combined with astrometric information from literature sources, we identify 44 young stars. Eighteen are previously known members ofmore » moving groups within 100 pc of the Sun. Twelve are new members, including one member of the TW Hydra moving group, one member of the 32 Orionis moving group, 9 members of Tucana-Horologium, one member of Argus, and two new members of AB Doradus. We also find 14 young star systems that are not members of any known groups. The remaining 33 star systems do not appear to be young. This appears to be evidence of a new population of nearby young stars not related to the known nearby young moving groups.« less

Multi-Sensory Approach to Search for Young Stellar Objects in CG4

NASA Astrophysics Data System (ADS)

Hoette, Vivian L.; Rebull, L. M.; McCarron, K.; Johnson, C. H.; Gartner, C.; VanDerMolen, J.; Gamble, L.; Matche, L.; McCartney, A.; Doering, M.; Crump, R.; Laorr, A.; Mork, K.; Steinbergs, E.; Wigley, E.; Caruso, S.; Killingstad, N.; McCanna, T.

2011-01-01

Individuals with disabilities - specifically individuals who are deaf or hard of hearing (DHH) and/or blind and visually-impaired (BVI) - have traditionally been underrepresented in the fields of Science, Technology, Engineering, and Math (STEM). The low incidence rate of these populations, coupled with geographic isolation, creates limited opportunities for students to work with and receive mentoring by professionals who not only have specialty knowledge in disability areas but also work in STEM fields. Yerkes Observatory scientists, along with educators from the Wisconsin School for the Deaf, the Wisconsin Center for the Blind and Visually Impaired, Breck School, and Oak Park and River Forest High School, are engaged in active research with a Spitzer Science Center (SSC) scientist. Our ultimate goals are threefold; to engage DHH and BVI students with equal success as their sighted and hearing peers, to share our techniques to make astronomy more accessible to DHH and BVI youth, and to generate a life-long interest which will lead our students to STEM careers. This poster tracks our work with an SSC scientist during the spring, summer, and fall of 2010. The group coauthored another AAS poster on finding Young Stellar Objects (YSO) in the CG4 Nebula in Puppis. During the project, the students, scientists and teachers developed a number of techniques for learning the necessary science as well as doing the required data acquisition and analysis. Collaborations were formed between students with disabilities and their non-disabled peers to create multi-media projects. Ultimately, the projects created for our work with NITARP will be disseminated through our professional connections in order to ignite a passion for astronomy in all students - with and without disabilities. This research was made possible through the NASA/IPAC Teacher Archive Research Project (NITARP) and was funded by NASA Astrophysics Data Program and Archive Outreach funds.

Age effect in generating mental images of buildings but not common objects.

PubMed

Piccardi, L; Nori, R; Palermo, L; Guariglia, C; Giusberti, F

2015-08-18

Imagining a familiar environment is different from imagining an environmental map and clinical evidence demonstrated the existence of double dissociations in brain-damaged patients due to the contents of mental images. Here, we assessed a large sample of young and old participants by considering their ability to generate different kinds of mental images, namely, buildings or common objects. As buildings are environmental stimuli that have an important role in human navigation, we expected that elderly participants would have greater difficulty in generating images of buildings than common objects. We found that young and older participants differed in generating both buildings and common objects. For young participants there were no differences between buildings and common objects, but older participants found easier to generate common objects than buildings. Buildings are a special type of visual stimuli because in urban environments they are commonly used as landmarks for navigational purposes. Considering that topographical orientation is one of the abilities mostly affected in normal and pathological aging, the present data throw some light on the impaired processes underlying human navigation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Catching the Next Burst: the periodic young stellar object EC 53 in Serpens Main is sharply brightening at 850 microns and at near-IR H-band and K-band

NASA Astrophysics Data System (ADS)

Johnstone, Doug; Mairs, Steve; Naylor, Tim; Contreras Pena, Carlos; Varricatt, Watson; Hodapp, Klaus; Herczeg, Gregory J.; Lee, Jeong-Eun; Yoo, Hyunju; Bell, Graham S.; Bower, Geoffrey C.; Aikawa, Yuri; Chen, Huei-Ru Vivien; Hatchell, Jennifer; Park, Sunkyung

2018-05-01

As part of our young stellar object (YSO) sub-mm monthly monitoring programme, the JCMT-Transient Survey (Herczeg et al. 2017 ApJ, 849, 43; Johnstone et al. 2018 ApJ, 854, 31), we are using SCUBA2 to monitor the 850 micron peak brightness of the YSO EC 53 (R.A.

Baryonic dark matter

NASA Technical Reports Server (NTRS)

Silk, Joseph

1991-01-01

Both canonical primordial nucleosynthesis constraints and large-scale structure measurements, as well as observations of the fundamental cosmological parameters, appear to be consistent with the hypothesis that the universe predominantly consists of baryonic dark matter (BDM). The arguments for BDM to consist of compact objects that are either stellar relics or substellar objects are reviewed. Several techniques for searching for halo BDM are described.

Brown dwarfs: at last filling the gap between stars and planets.

PubMed

Zuckerman, B

2000-02-01

Until the mid-1990s a person could not point to any celestial object and say with assurance that "here is a brown dwarf." Now dozens are known, and the study of brown dwarfs has come of age, touching upon major issues in astrophysics, including the nature of dark matter, the properties of substellar objects, and the origin of binary stars and planetary systems.

On Mature Reflection: "Strange Objects" and the Cultivation of Reflective Reading.

ERIC Educational Resources Information Center

Heyde, Emma

2000-01-01

Examines Gary Crew's novel written for a young adult audience, called "Strange Objects," a story containing verifiable historical fact interwoven with elements of fiction and the supernatural. Shows how the numerous genres and viewpoints in the book challenge and contradict one another, forcing young readers to perform resistant readings…

NTT Observations Indicate that Brown Dwarfs Form Like Stars

NASA Astrophysics Data System (ADS)

2001-06-01

Dusty Disks Detected around Very Young Substellar Objects in the Orion Nebula Summary An international team of astronomers [2] is announcing today the discovery of dusty disks surrounding numerous very faint objects that are believed to be recently formed Brown Dwarfs in the Orion Nebula [3]. This finding is based on detailed observations with SOFI, a specialised infrared-sensitive instrument at the ESO 3.5-m New Technology Telescope at the La Silla Observatory. It is of special interest because it sheds light on the origin and nature of substellar objects, known as "Brown Dwarfs" . In particular, these results suggest that Brown Dwarfs share a common origin with stars and that Brown Dwarfs are more similar in nature to stars than to planets and, like stars, have the potential to form with accompanying systems of planets. Moreover, the presence of dusty protoplanetary disks around the faintest objects in the Orion Nebula cluster confirms both the membership of these faint stars in the cluster and their nature as bona-fide substellar objects, making this the largest population of Brown Dwarf objects yet known . These important results are being reported today to the American Astronomical Society Meeting in Pasadena (California, USA). PR Photo 22a/01 : Infrared picture of the Orion Nebula (NTT + SOFI). PR Photo 22b/01 : "Finding Chart" for Very Young Brown Dwarfs in the Orion Nebula. PR Photo 22c/01 : Animated GIF presentation of PR Photos 22a+b/01. Faint substellar objects in the Milky Way Over the past 5 years, several groups of astronomers have identified a type of very faint, substellar objects within our Milky Way galaxy. These gaseous objects have very low masses and will never shine like normal stars because they cannot achieve central temperatures high enough for sustained thermal nuclear reactions to occur in their cores. Such objects weigh less than about 7% of our Sun and have been variously called "Brown Dwarfs" , "Failed Stars" or "Super Planets

Children's Use of Objects in an Early Years Playground

ERIC Educational Resources Information Center

Bateman, Amanda; Church, Amelia

2017-01-01

Early childhood research has investigated children's use of objects largely focusing on cognitive and motor development. Yet members of a particular culture, such as young children's peer groups, use objects that have cultural relevance as "conversational" items, as a means to interacting with other members of the group. This article…

Assessing Multiple Object Tracking in Young Children Using a Game

ERIC Educational Resources Information Center

Ryokai, Kimiko; Farzin, Faraz; Kaltman, Eric; Niemeyer, Greg

2013-01-01

Visual tracking of multiple objects in a complex scene is a critical survival skill. When we attempt to safely cross a busy street, follow a ball's position during a sporting event, or monitor children in a busy playground, we rely on our brain's capacity to selectively attend to and track the position of specific objects in a dynamic scene. This…

Children's Understanding of the Distinction between Natural and Crafted Objects.

ERIC Educational Resources Information Center

Chen, J. Q.; And Others

This study examined whether evidence for understanding the distinction between natural and man-made aspects of the world can be found in young children. Children 3, 5, and 7 years of age were asked to make judgments about the origins of 12 objects and people's ability to change the objects. The objects were evenly divided into naturally occurring…

Program of Vocational Rehabilitation for Young Adult Offenders.

ERIC Educational Resources Information Center

Pennsylvania State Correctional Inst., Camp Hill.

Full development of the educational, occupational, and attitudinal abilities of young delinquents admitted to the Camp Hill State Correctional Institute was the object of this Elementary and Secondary Education Act Title I Program. Young adults 15-21 years committed to Camp Hill average 6.1 on the standard educational battery test and their…

A possible brown dwarf companion to Gliese 569

NASA Technical Reports Server (NTRS)

Forrest, W. J.; Shure, Mark; Skrutskie, M. F.

1988-01-01

A faint cool companion to Gliese 569, discovered during an IR imaging survey of nearby stars, may be the lowest-mass stellar object yet found. The companion is somewhat cooler in its 1.65-3.75-micron energy distribution than the coolest known main-sequence stars, indicating a low mass. Despite its lower temperature, it is more luminous than similar extremely low-mass stars, suggesting that it is either a young low-mass star evolving toward the main sequence or a cooling substellar brown dwarf. The primary star has emission lines and a low space velocity and exhibits flaring, all of which imply youth for this system. Observations of Gliese 569 and its companion over a period of 2 yr confirm the common proper motion expected of a true binary. The 5-arcsec apparent separation (50 AU) implies an orbital period of roughly 500 yr, which will permit an eventual direct determination of the mass of the companion.

The young, tight, and low-mass binary TWA22AB: a new calibrator for evolutionary models?. Orbit, spectral types, and temperature

NASA Astrophysics Data System (ADS)

Bonnefoy, M.; Chauvin, G.; Dumas, C.; Lagrange, A.-M.; Beust, H.; Desort, M.; Teixeira, R.; Ducourant, C.; Beuzit, J.-L.; Song, I.

2009-11-01

Context: Tight binaries discovered in young, nearby associations are ideal targets for providing dynamical mass measurements to test the physics of evolutionary models at young ages and very low masses. Aims: We report the binarity of TWA22 for the first time. We aim at monitoring the orbit of this young and tight system to determine its total dynamical mass using an accurate distance determination. We also intend to characterize the physical properties (luminosity, effective temperature, and surface gravity) of each component based on near-infrared photometric and spectroscopic observations. Methods: We used the adaptive-optics assisted imager NACO to resolve the components, to monitor the complete orbit and to obtain the relative near-infrared photometry of TWA22 AB. The adaptive-optics assisted integral field spectrometer SINFONI was also used to obtain medium-resolution (Rλ=1500-2000) spectra in JHK bands. Comparison with empirical and synthetic librairies were necessary for deriving the spectral type, the effective temperature, and the surface gravity for each component of the system. Results: Based on an accurate trigonometric distance (17.5 ± 0.2 pc) determination, we infer a total dynamical mass of 220 ± 21 MJup for the system. From the complete set of spectra, we find an effective temperature T_eff=2900+200-200 K for TWA22 A and T_eff=2900+200-100 K for TWA22 B and surface gravities between 4.0 and 5.5 dex. From our photometry and an M6 ± 1 spectral type for both components, we find luminosities of log(L/L⊙) = -2.11 ± 0.13 dex and log(L/L⊙) = -2.30 ± 0.16 dex for TWA22 A and B, respectively. By comparing these parameters with evolutionary models, we question the age and the multiplicity of this system. We also discuss a possible underestimation of the mass predicted by evolutionary models for young stars close to the substellar boundary. Based on service-mode observations (072.C-0644, 073.C-0469, 075.C-0521, 076.C-0554, 078.C-0510, 080.C-0581

Brown dwarfs: At last filling the gap between stars and planets

PubMed Central

Zuckerman, Ben

2000-01-01

Until the mid-1990s a person could not point to any celestial object and say with assurance that “here is a brown dwarf.” Now dozens are known, and the study of brown dwarfs has come of age, touching upon major issues in astrophysics, including the nature of dark matter, the properties of substellar objects, and the origin of binary stars and planetary systems. PMID:10655468

McDonald Observatory Planetary Search - A high precision stellar radial velocity survey for other planetary systems

NASA Technical Reports Server (NTRS)

Cochran, William D.; Hatzes, Artie P.

1993-01-01

The McDonald Observatory Planetary Search program surveyed a sample of 33 nearby F, G, and K stars since September 1987 to search for substellar companion objects. Measurements of stellar radial velocity variations to a precision of better than 10 m/s were performed as routine observations to detect Jovian planets in orbit around solar type stars. Results confirm the detection of a companion object to HD114762.

Attitudes of Young African American Fathers Toward Early Childbearing

ERIC Educational Resources Information Center

Davies, Susan L.; Dix, Emily S.; Rhodes, Scott D.; Harrington, Kathleen F.; Frison, Sonja; Willis, Leigh

2004-01-01

Objective : To qualitatively examine the perceptions of young fathers toward issues related to early childbearing. Methods : Focus groups were held with male partners of adolescent females who had become pregnant while participating in an HIV-prevention trial. Results : Primary domains that emerged included young male's desire for pregnancy, their…

Sensitivity to Relational Similarity and Object Similarity in Apes and Children.

PubMed

Christie, Stella; Gentner, Dedre; Call, Josep; Haun, Daniel Benjamin Moritz

2016-02-22

Relational reasoning is a hallmark of sophisticated cognition in humans. Does it exist in other primates? Despite some affirmative answers, there appears to be a wide gap in relational ability between humans and other primates--even other apes. Here, we test one possible explanation for this gap, motivated by developmental research showing that young humans often fail at relational reasoning tasks because they focus on objects instead of relations. When asked, "duck:duckling is like tiger:?," preschool children choose another duckling (object match) rather than a cub. If other apes share this focus on concrete objects, it could undermine their relational reasoning in similar ways. To test this, we compared great apes and 3-year-old humans' relational reasoning on the same spatial mapping task, with and without competing object matches. Without competing object matches, both children and Pan species (chimpanzees and bonobos) spontaneously used relational similarity, albeit children more so. But when object matches were present, only children responded strongly to them. We conclude that the relational gap is not due to great apes' preference for concrete objects. In fact, young humans show greater object focus than nonhuman apes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Learning Activities for the Young Handicapped Child.

ERIC Educational Resources Information Center

Bailey, Don; And Others

Presented is a collection of learning activities for the young handicapped child covering 295 individual learning objectives in six areas of development: gross motor skills, fine motor skills, social skills, self help skills, cognitive skills, and language skills. Provided for each learning activity are the teaching objective, teaching procedures,…

A new free-floating planet in the Upper Scorpius association

NASA Astrophysics Data System (ADS)

Peña Ramírez, K.; Béjar, V. J. S.; Zapatero Osorio, M. R.

2016-02-01

We report on a deep photometric survey covering an area of 1.17 deg2 in the young Upper Scorpius stellar association using VIMOS Iz and UKIDSS ZJHK data that was taken with several years in between. The search for the least massive population of Upper Scorpius (~5-10 Myr, 145 pc) is performed on the basis of various optical and infrared color-color and color-magnitude diagrams, including WISE photometry, in the magnitude interval J = 14.5-19 mag (completeness), which corresponds to substellar masses from 0.028 through 0.004 M⊙ at the age and distance of Upper Scorpius. We also present the proper motion analysis of the photometric candidates, finding that two objects successfully pass all photometric and astrometric criteria for membership in the young stellar association. One of them, USco J155150.2-213457, is a new discovery. We obtained low resolution, near-infrared spectroscopy (R ~ 450, 0.85-2.35 μm) of this new finding using the FIRE instrument. We confirmed its low-gravity atmosphere expected for an Upper Scorpius member (weak alkaline lines, strong VO absorption, peaked H-band pseudocontinuum). By comparison with spectroscopic standards, we derive a spectral type of L6 ± 1, and estimate a mass of ≈0.008-0.010 M⊙ for USco J155150.2-213457. The colors and spectral slope of this object resemble those of other young, cool members of Upper Scorpius and σ Orionis (~3 Myr) and field, high gravity dwarfs of related classification in contrast with the very red indices of field, low gravity, L-type dwarfs of intermediate age. USco J155150.2-213457, which does not show infrared flux excesses up to 4.5 μm, becomes one of the least massive and latest type objects known in the entire Upper Scorpius stellar association.

Young Adults' Perceptions of Calcium Intake and Health: A Qualitative Study

ERIC Educational Resources Information Center

Marcinow, Michelle L.; Randall Simpson, Janis A.; Whiting, Susan J.; Jung, Mary E.; Buchholz, Andrea C.

2017-01-01

Many young Canadian adults are not meeting dietary calcium recommendations. This is concerning as adequate calcium is important throughout young adulthood to maximize peak bone mass for osteoporosis prevention. There are limited studies that have explored young adults' perceptions toward calcium and health. Our objectives were to determine young…

Cue Reactivity in Young Marijuana Smokers

PubMed Central

Gray, Kevin M.; LaRowe, Steven D.; Upadhyaya, Himanshu P.

2008-01-01

Objective To develop and evaluate the feasibility of a cue reactivity paradigm for young marijuana smokers. Method A laboratory procedure was developed involving neutral- and marijuana-related imagery, video, and in vivo cues. Fifteen adolescents and young adults with cannabis use disorders completed the procedure. Continuous Skin Conductance (SC) and Heart Rate (HR) were measured throughout the procedure. Participants completed questionnaires regarding marijuana craving before, during and after cue presentations. Results Higher levels of craving and SC were observed during marijuana cue presentations. Conclusions The procedure appears to elicit cue reactivity among adolescents and young adults with cannabis use disorders and should be further evaluated and refined with a larger sample. Implications for future studies are discussed. PMID:19071985

Young Children as Curators

ERIC Educational Resources Information Center

Hope, Alice

2018-01-01

Literature that addresses young children's learning in galleries and museums typically concentrates on what is already offered and discusses what has proven to be effective, or not, in accommodating their needs. This article offers insight into how objects can be explored with early years children at school, to create greater understanding of…

Measuring the environmental awareness of young farmers

NASA Astrophysics Data System (ADS)

Kountios, G.; Ragkos, A.; Padadavid, G.; Hadjimitsis, D.

2017-09-01

Young farmers in Europe, especially the beneficiaries of Common Agricultural Policy (CAP) funding schemes, are considered as the ones who could ensure the sustainability of the European Model of Agriculture. Economic efficiency and competitiveness, aversion of depopulation of rural areas and environmental protection constitute some of the key objectives of the CAP and young farmers are expected to play a role to all of them. This study proposes a way of measuring the potential of young farmers to contribute to the latter objectives of the CAP by estimating their environmental attitudes. Data from a questionnaire survey of 492 Greek young farmers were used to design a latent construct measuring their environmental attitudes. The latent construct was designed by means of an Explanatory Factor Analysis (EFA) using the responses to a set of 12 Likert-scale items. The results the EFA yielded a latent construct with three factors related to "Environmental pollution and policies (EPP)", "Environmental factors and food quality (EFF)" and "Farming practices and the environment". These results were validated through a CFA where 8 items in total were categorized in the three factors (latent variables). The utilization of the latent construct for the effective implementation of CAP measures could ameliorate the relationships of agriculture and environment in general.

Manipulation of a fragile object by elderly individuals.

PubMed

Gorniak, Stacey L; Zatsiorsky, Vladimir M; Latash, Mark L

2011-08-01

We investigated strategies of healthy elderly participants (74-84 years old) during prehension and transport of an object with varying degrees of fragility. Fragility was specified as the maximal normal force that the object could withstand without collapsing. Specifically, kinetic and kinematic variables as well as and force covariation indices were quantified and compared to those shown by young healthy persons (19-28 years old). We tested three hypotheses related to age-related changes in two safety margins (slip safety margin and crush safety margin) and indices of force covariation. Compared to young controls, elderly individuals exhibited a decrease in object acceleration and an increase in movement time, an increase in grip force production, a decrease in the correlation between grip and load forces, an overall decrease in indices of multi-digit synergies, and lower safety margin indices computed with respect to both dropping and crushing the object. Elderly participants preferred to be at a relatively lower risk of crushing the object even if this led to a higher risk of dropping it. Both groups showed an increase in the index of synergy stabilizing total normal force produced by the four fingers with increased fragility of the object. Age-related changes are viewed as a direct result of physiological changes due to aging, not adaptation to object fragility. Such changes in overall characteristics of prehension likely reflect diminished synergic control by the central nervous system of finger forces with aging. The findings corroborate an earlier hypothesis on an age-related shift from synergic to element-based control.

Associations between young children's perceived and actual ball skill competence and physical activity.

PubMed

Barnett, Lisa M; Ridgers, Nicola D; Salmon, Jo

2015-03-01

The relationship between actual and perceived object control competence (ball skills) and the contribution to young children's physical activity is not known. Cross sectional study. The Test Gross Motor Development-2 assessed actual object control competence and a modified version of the Pictorial Scale of Perceived Competence and Social Acceptance for Young Children assessed perceived object control competence. Moderate- to vigorous-intensity physical activity was measured via accelerometry. Three mixed regression models were performed: (i) object control competence as the predictor and the outcome as perceived object control, (ii) perceived object control competence as the predictor and the outcome moderate to vigorous physical activity and (iii) actual object control as the predictor and the outcome moderate to vigorous physical activity. Models adjusted for school clustering, monitor wear time, sex and age. Interactions between respective predictor variables and sex were performed if warranted. A total of 102 children (56% boys, 44% girls) aged 4-8 years (M 6.3, SD 0.92) completed assessments. Girls had lower perceived and actual object control competence and were less active than boys. Actual object control competence was positively associated with perceived object control competence (B=0.11, t(96)=2.25, p<0.001, p=0.027) and this relationship did not differ by sex (p=0.449); however, neither actual (p=0.092) nor perceived object control competence (p=0.827) were associated with moderate to vigorous physical activity. Young children's perceived ball skill abilities appear to relate to actual competence; however, these measures were not associated with physical activity. In older children, object control skill is associated with physical activity so targeting young children's object control skills is an intervention priority. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Looking for the Coldest Atmospheres: a Search for Planetary Mass Companions around T and Y Brown Dwarfs

NASA Astrophysics Data System (ADS)

Fontanive, Clemence

2017-08-01

We propose to obtain WFC3/IR imaging of the very coolest brown dwarfs (T < 800 K) to search for substellar and planetary-mass companions to these objects. Companions discovered by this program would likely be analogues of the 250 K brown dwarf WISE 0855 and would provide vital benchmark objects for theoretical models, closing the gap in mass and temperature between brown dwarfs and planets. Finding such an object as a member of a binary system would be even more valuable as it would allow for the measurement of dynamical masses. We recently placed the first constraints to date on the binary frequency for brown dwarfs with spectral types >T8. This program will triple our current sample size, a requirement in order to confirm our current results and compare substellar binary properties for various spectral type and age populations. The WFC3/IR plate will allow us to probe near equal-mass binaries down to separations of 0.2 (2-3 AU for the typical distances of our targets). True cool companions should show strong absorption around 1.4 um as a result of the deep water absorption band observed at that wavelength in substellar spectra. We therefore propose observations in the WFC3 F127M and F139M filters which will allow us to robustly identify bona fide candidates and distinguish them from background stars based on this spectral feature. Most of our targets lack suitable NGS AO guide stars or LGS AO tip-tilt stars to be observed with ground-based telescopes, and the 1.4 um water band is often unobservable from the ground due to telluric water absorption. WFC3 on HST is thus the only instrument suitable for these observations.

World Ocean Circulation Experiment (WOCE) Young Investigator Workshops

NASA Technical Reports Server (NTRS)

Austin, Meg

2004-01-01

The World Ocean Circulation Experiment (WOCE) Young Investigator Workshops goals and objectives are: a) to familiarize Young Investigators with WOCE models, datasets and estimation procedures; b) to offer intensive hands-on exposure to these models ard methods; c) to build collaborations among junior scientists and more senior WOCE investigators; and finally, d) to generate ideas and projects leading to fundable WOCE synthesis projects. To achieve these goals and objectives, the Workshop will offer a mixture of tutorial lectures on numerical models and estimation procedures, advanced seminars on current WOCE synthesis activities and related projects, and the opportunity to conduct small projects which put into practice the techniques advanced in the lectures.

Imaging Protoplanets: Observing Transition Disks with Non-Redundant Masking

NASA Astrophysics Data System (ADS)

Sallum, Stephanie

2017-01-01

Transition disks - protoplanetary disks with inner, solar system sized clearings - may be shaped by young planets. Directly imaging protoplanets in these objects requires high contrast and resolution, making them promising targets for future extremely large telescopes. The interferometric technique of non-redundant masking (NRM) is well suited for these observations, enabling companion detection for contrasts of 1:100 - 1:1000 at or within the diffraction limit. My dissertation focuses on searching for and characterizing companions in transition disk clearings using NRM. I will briefly describe the technique and present spatially resolved observations of the T Cha and LkCa 15 transition disks. Both of these objects hosted posited substellar companions. However multi-epoch T Cha datasets cannot be explained by planets orbiting in the disk plane. Conversely, LkCa 15 data taken with the Large Binocular Telescope (LBT) in single-aperture mode reveal the presence of multiple forming planets. The dual aperture LBT will provide triple the angular resolution of these observations, dramatically increasing the phase space for exoplanet detection. I will also present new results from the dual-aperture LBT, with similar resolution to that expected for next generation facilities like GMT.

Confirmation of the binary status of Chamaeleon Hα 2 - a very young low-mass binary in Chamaeleon

NASA Astrophysics Data System (ADS)

Schmidt, T. O. B.; Neuhäuser, R.; Vogt, N.; Seifahrt, A.; Roell, T.; Bedalov, A.

2008-06-01

Context: Neuhäuser & Comerón (1998, Science, 282, 83; 1999, A&A, 350, 612) presented direct imaging evidence, as well as first spectra, of several young stellar and sub-stellar M6- to M8-type objects in the Cha I dark cloud. One of these objects is Cha Hα 2, classified as brown dwarf candidate in several publications and suggested as possible binary in Neuhäuser et al. (2002, A&A, 384, 999). Aims: We have searched around Cha Hα 2 for close and faint companions with adaptive optics imaging. Methods: Two epochs of direct imaging data were taken with the Very Large Telescope (VLT) Adaptive Optics instrument NACO in February 2006 and March 2007 in Ks-band together with a Hipparcos binary for astrometric calibration. Moreover, we took a J-band image in March 2007 to get color information. We retrieved an earlier image from 2005 from the European Southern Observatory (ESO) Science Archive Facility, increasing the available time coverage. After confirmation of common proper motion, we deduce physical parameters of the objects by spectroscopy, like temperature and mass. Results: We find Cha Hα 2 to be a very close binary of 0.16 arcsec separation, having a flux ratio of 0.91, thus having almost equal brightness and indistinguishable spectral types within the errors. We show that the two tentative components of Cha Hα 2 form a common proper motion pair, and that neither component is a non-moving background object. We even find evidence for orbital motion. A combined spectrum of both stars spanning optical and near-infrared parts of the spectral energy distribution yields a temperature of 3000 ± 100 K, corresponding to a spectral type of M6 ± 1 and a surface gravity of log{g} = 4.0+0.75-0.5, both from a comparison with GAIA model atmospheres. Furthermore, we obtained an optical extinction of AV ≃ 4.3 mag from this comparison. Conclusions: We derive masses of 0.110 M⊙ (≥0.070 M⊙) and 0.124 M⊙ (≥0.077 M⊙) for the two components of Cha Hα 2, i

The emerging causal understanding of institutional objects.

PubMed

Noyes, Alexander; Keil, Frank C; Dunham, Yarrow

2018-01-01

Institutional objects, such as money, drivers' licenses, and borders, have functions because of their social roles rather than their immediate physical properties. These objects are causally different than standard artifacts (e.g. hammers, chairs, and cars), sharing more commonality with other social roles. Thus, they inform psychological theories of human-made objects as well as children's emerging understanding of social reality. We examined whether children (N=180, ages 4-9) differentiate institutional objects from standard artifacts. Specifically, we examine whether children understand that mutual intentions (i.e., the intentions of a social collective) underlie the functional affordances of institutional objects in ways that they do not for standard artifacts. We find that young children assimilate institutional objects into their intuitive theories of standard artifacts; children begin to differentiate between the domains in the elementary school years. Published by Elsevier B.V.

Astrophysics of brown dwarfs; Proceedings of the Workshop, George Mason University, Fairfax, VA, Oct. 14, 15, 1985

NASA Technical Reports Server (NTRS)

Kafatos, Minas C. (Editor); Harrington, Robert S. (Editor); Maran, Stephen P. (Editor)

1986-01-01

Various reports on theoretical and observational studies of brown dwarfs (BDs) are presented. The topics considered include: astrometric detection of BDs, search for substellar companions to nearby stars using IR imaging, constraints on BD mass function from optical and IR searches, properties of stellar objects near the main sequence mass limit, search for low-mass stellar companions with the HF precision velocity technique, dynamical search for substellar objects, search for BDs in the IRAS data base, deep CCD survey for low mass stars in the disk and halo, the Berkeley search for a faint solar companion, the luminosity function for late M stars, astronomic search for IR dwarfs, and the role of the Space Telescope in the detection of BDs. Also addressed are: theoretical significance of BDs, evolution of super-Jupiters, compositional indicators in IR spectra of BDs, evolution of BDs and the evolutionary status of VB8B, the position of BDs on universal diagrams, theoretical determination of the minimum protostellar mass, Population II BDs and dark halos.

OBJECT REPRESENTATION, IDENTITY, AND THE PARADOX OF EARLY PERMANENCE: Steps Toward a New Framework.

PubMed

Meltzoff, Andrew N; Moore, M Keith

1998-01-01

The sensorimotor theory of infancy has been overthrown, but there is little consensus on a replacement. We hypothesize that a capacity for representation is the starting point for infant development, not its culmination. Logical distinctions are drawn between object representation, identity, and permanence. Modern experiments on early object permanence and deferred imitation suggest: (a) even for young infants, representations persist over breaks in sensory contact, (b) numerical identity of objects ( O s) is initially specified by spatiotemporal criteria (place and trajectory), (c) featural and functional identity criteria develop, (d) events are analyzed by comparing representations to current perception, and (e) representation operates both prospectively, anticipating future contacts with an O , and retrospectively, reidentifying an O as the "same one again." A model of the architecture and functioning of the early representational system is proposed. It accounts for young infants' behavior toward absent people and things in terms of their efforts to determine the identity of objects. Our proposal is developmental without denying innate structure and elevates the power of perception and representation while being cautious about attributing complex concepts to young infants.

Early-stage young stellar objects in the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Oliveira, J. M.; van Loon, J. Th.; Sloan, G. C.; Sewiło, M.; Kraemer, K. E.; Wood, P. R.; Indebetouw, R.; Filipović, M. D.; Crawford, E. J.; Wong, G. F.; Hora, J. L.; Meixner, M.; Robitaille, T. P.; Shiao, B.; Simon, J. D.

2013-02-01

We present new observations of 34 young stellar object (YSO) candidates in the Small Magellanic Cloud (SMC). The photometric selection required sources to be bright at 24 and 70 μm (to exclude evolved stars and galaxies). The anchor of the analysis is a set of Spitzer Infrared Spectrograph (IRS) spectra, supplemented by ground-based 3-5 μm spectra, Spitzer Infrared Array Camera and Multiband Imaging Photometer for Spitzer photometry, near-infrared (IR) imaging and photometry, optical spectroscopy and radio data. The sources' spectral energy distributions and spectral indices are consistent with embedded YSOs; prominent silicate absorption is observed in the spectra of at least 10 sources, silicate emission is observed towards four sources. Polycyclic aromatic hydrocarbon (PAH) emission is detected towards all but two sources. Based on band ratios (in particular the strength of the 11.3-μm and the weakness of the 8.6-μm bands) PAH emission towards SMC YSOs is dominated by predominantly small neutral grains. Ice absorption is observed towards 14 sources in the SMC. The comparison of H2O and CO2 ice column densities for SMC, Large Magellanic Cloud and Galactic samples suggests that there is a significant H2O column density threshold for the detection of CO2 ice. This supports the scenario proposed by Oliveira et al., where the reduced shielding in metal-poor environments depletes the H2O column density in the outer regions of the YSO envelopes. No CO ice is detected towards the SMC sources. Emission due to pure rotational 0-0 transitions of molecular hydrogen is detected towards the majority of SMC sources, allowing us to estimate rotational temperatures and H2 column densities. All but one source are spectroscopically confirmed as SMC YSOs. Based on the presence of ice absorption, silicate emission or absorption and PAH emission, the sources are classified and placed in an evolutionary sequence. Of the 33 YSOs identified in the SMC, 30 sources populate different

Involving a young person in the development of a digital resource in nurse education.

PubMed

Fenton, Gaynor

2014-01-01

Health policies across western societies have embedded the need for service user and carer perspectives in service design and delivery of educational programmes. There is a growing recognition of the need to include the perspectives of children and young people as service users in the design and delivery of child focused educational programmes. Digital storytelling provides a strategy for student nurses to gain insight into the lived experiences of children and young people. Engaging with these stories enables students to develop an understanding of a young persons' experience of healthcare. This paper outlines a project that developed a digital learning object based upon a young person's experience of cancer and student evaluations of the digital learning object as a teaching and learning strategy. Over 80% of students rated the digital learning object as interesting and were motivated to explore its content. In addition, the evaluation highlighted that listening to the young person's experiences of her treatment regimes was informative and assisted understanding of a patients' perspective of care delivery. Copyright © 2013 Elsevier Ltd. All rights reserved.

Color-Object Interference: Further Tests of an Executive Control Account

ERIC Educational Resources Information Center

La Heij, Wido; Boelens, Harrie

2011-01-01

Young children are slower in naming the color of a meaningful picture than in naming the color of an abstract form (Stroop-like color-object interference). The current experiments tested an executive control account of this phenomenon. First, color-object interference was observed in 6- and 8-year-olds but not in 12- and 16-year-olds (Experiment…

Object-Based Epistemology at a Creationist Museum

ERIC Educational Resources Information Center

Wendel, Paul J.

2011-01-01

In a regional young-earth creationist museum, objects are presented as if they speak for themselves, purportedly embodying proof that the earth is less than 10,000 years old, that humans have lived on earth throughout its history, and that dinosaurs and humans lived simultaneously. In public lectures, tours, and displays, museum associates…

Postsecondary Employment Experiences Among Young Adults With an Autism Spectrum Disorder RH: Employment in Young Adults With Autism

PubMed Central

Roux, Anne M.; Shattuck, Paul T.; Cooper, Benjamin P.; Anderson, Kristy A.; Wagner, Mary; Narendorf, Sarah C.

2013-01-01

Objective We examined postsecondary employment experiences of young adults with an autism spectrum disorder (ASD) and compared these outcomes with those of young adults with different disabilities. Method Data were from Wave 5 of the National Longitudinal Transition Study 2 (NLTS2), a nationally representative survey of young adults who had received special education services during high school. We examined the prevalence of ever having had—and currently having—a paid job at 21–25 years of age. We analyzed rates of full employment, wages earned, number of jobs held since high school, and job types. Results About half (53.4%) of young adults with an ASD had ever worked for pay outside the home since leaving high school, the lowest rate among disability groups. Young adults with an ASD earned an average of $8.10 per hour, significantly lower than average wages for young adults in the comparison groups, and held jobs that clustered within fewer occupational types. Odds of ever having had a paid job were higher for those who were older, from higher-income households, and with better conversational abilities or functional skills. Conclusions Findings of worse employment outcomes for young adults with an ASD suggest this population is experiencing particular difficulty in successfully transitioning into employment. Research is needed to determine strategies for improving outcomes as these young adults transition into adulthood. PMID:23972695

Circumstellar Structure Properties of Young Stellar Objects: Envelopes, Bipolar Outflows, and Disks

NASA Astrophysics Data System (ADS)

Kwon, Woojin

2009-12-01

Physical properties of the three main structures in young stellar objects (YSOs), envelopes, bipolar outflows, and circumstellar disks, have been studied using radio interferometers: the Berkeley-Illinois-Maryland Association (BIMA) array and the Combined Array for Research in Millimeter-wave Astronomy (CARMA). (1) Envelopes. Three Class 0 YSOs (L1448 IRS 2, L1448 IRS 3, and L1157) have been observed by CARMA at λ = 1.3 mm and 2.7 mm continuum. Through visibility modeling to fit the two wavelength continuum data simultaneously, we found that the dust opacity spectral index (β) of Class 0 YSOs is around unity, which implies that dust grains have significantly grown already at the earliest stage. In addition, we discussed the radial dependence of β detected in L1448 IRS 3B and also estimated the density distribution of the three targets. (2) Bipolar outflows. Polarimetric observations in the λ = 1.3 mm continuum and CO, as well as spectral line observations in 13CO and C18O have been carried out toward L1448 IRS 3, which has three Class 0 YSOs, using BIMA. We clearly identified two interacting bipolar outflows from the "binary system" of IRS 3A and 3B and estimated the velocity, inclination, and opening angle of the 3B bipolar outflow, using Bayesian inference. Also, we showed that the "binary system" can be bound gravitationally and we estimated the specific angular momentum, which is between those of binary stars and molecular cloud cores. In addition, we marginally detected linear polarizations at the center of IRS 3B (implying a toroidal magnetic field) in continuum and at the bipolar outflow region in CO. (3) Circumstellar disks. We present the results of 6 objects (CI Tau, DL Tau, DO Tau, FT Tau, Haro 6-13, and HL Tau) in our T Tauri disk survey using CARMA. The data consist of λ = 1.3 mm and 2.7 mm continuum with an angular resolution up to 0.13". Through visibility modeling of two disk models (power-law disk with a Gaussian edge and viscous accretion

A multi-wavelength interferometric study of the massive young stellar object IRAS 13481-6124

NASA Astrophysics Data System (ADS)

Boley, Paul A.; Kraus, Stefan; de Wit, Willem-Jan; Linz, Hendrik; van Boekel, Roy; Henning, Thomas; Lacour, Sylvestre; Monnier, John D.; Stecklum, Bringfried; Tuthill, Peter G.

2016-02-01

We present new mid-infrared interferometric observations of the massive young stellar object IRAS 13481-6124, using VLTI/MIDI for spectrally-resolved, long-baseline measurements (projected baselines up to ~120 m) and GSO/T-ReCS for aperture-masking interferometry in five narrow-band filters (projected baselines of ~1.8-6.4 m) in the wavelength range of 7.5-13μm. We combine these measurements with previously-published interferometric observations in the K and N bands in order to assemble the largest collection of infrared interferometric observations for a massive YSO to date. Using a combination of geometric and radiative-transfer models, we confirm the detection at mid-infrared wavelengths of the disk previously inferred from near-infrared observations. We show that the outflow cavity is also detected at both near- and mid-infrared wavelengths, and in fact dominates the mid-infrared emission in terms of total flux. For the disk, we derive the inner radius (~1.8 mas or ~6.5 AU at 3.6 kpc), temperature at the inner rim (~1760 K), inclination (~48°) and position angle (~107°). We determine that the mass of the disk cannot be constrained without high-resolution observations in the (sub-)millimeter regime or observations of the disk kinematics, and could be anywhere from ~10-3 to 20M⊙. Finally, we discuss the prospects of interpreting the spectral energy distributions of deeply-embedded massive YSOs, and warn against attempting to infer disk properties from the spectral energy distribution. Based in part on observations with the Very Large Telescope Interferometer of the European Southern Observatory, under program IDs 384.C-0625, 086.C-0543, 091.C-0357.

Young Stellar Objects in the Massive Star-forming Regions W51 and W43

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saral, G.; Audard, M.; Hora, J. L.

We present the results of our investigation of the star-forming complexes W51 and W43, two of the brightest in the first Galactic quadrant. In order to determine the young stellar object (YSO) populations in W51 and W43 we used color–magnitude relations based on Spitzer mid-infrared and 2MASS/UKIDSS near-infrared data. We identified 302 Class I YSOs and 1178 Class II/transition disk candidates in W51, and 917 Class I YSOs and 5187 Class II/transition disk candidates in W43. We also identified tens of groups of YSOs in both regions using the Minimal Spanning Tree (MST) method. We found similar cluster densities inmore » both regions, even though Spitzer was not able to probe the densest part of W43. By using the Class II/I ratios, we traced the relative ages within the regions and, based on the morphology of the clusters, we argue that several sites of star formation are independent of one another in terms of their ages and physical conditions. We used spectral energy distribution-fitting to identify the massive YSO (MYSO) candidates since they play a vital role in the star formation process, and then examined them to see if they are related to any massive star formation tracers such as UCH ii regions, masers, or dense fragments. We identified 17 MYSO candidates in W51, and 14 in W43, respectively, and found that groups of YSOs hosting MYSO candidates are positionally associated with H ii regions in W51, though we do not see any MYSO candidates associated with previously identified massive dense fragments in W43.« less

Predictable Locations Aid Early Object Name Learning

PubMed Central

Benitez, Viridiana L.; Smith, Linda B.

2012-01-01

Expectancy-based localized attention has been shown to promote the formation and retrieval of multisensory memories in adults. Three experiments show that these processes also characterize attention and learning in 16- to 18- month old infants and, moreover, that these processes may play a critical role in supporting early object name learning. The three experiments show that infants learn names for objects when those objects have predictable rather than varied locations, that infants who anticipate the location of named objects better learn those object names, and that infants integrate experiences that are separated in time but share a common location. Taken together, these results suggest that localized attention, cued attention, and spatial indexing are an inter-related set of processes in young children that aid in the early building of coherent object representations. The relevance of the experimental results and spatial attention for everyday word learning are discussed. PMID:22989872

The Class of Jsolated Stars and Luminous Planetary Nebulae in old stellar populations

NASA Astrophysics Data System (ADS)

Sabach, Efrat; Soker, Noam

2018-06-01

We suggest that stars whose angular momentum (J) does not increase by a companion, star or planet, along their post-main sequence evolution have much lower mass loss rates along their giant branches. Their classification to a separate group can bring insight on their late evolution stages. We here term these Jsolated stars. We argue that the mass loss rate of Jsolated stars is poorly determined because the mass loss rate expressions on the giant branches are empirically based on samples containing stars that experience strong binary interaction, with stellar or sub-stellar companions, e.g., planetary nebula (PN) progenitors. We use our earlier claim for a low mass loss rate of asymptotic giant branch (AGB) stars that are not spun-up by a stellar or substellar companion to show that we can account for the enigmatic finding that the brightest PNe in old stellar populations reach the same luminosity as the brightest PNe in young populations. It is quite likely that the best solution to the existence of bright PNe in old stellar populations is the combination of higher AGB luminosities, as obtained in some new stellar models, and the lower mass loss rates invoked here.

An eccentric companion at the edge of the brown dwarf desert orbiting the 2.4 M⊙ giant star HIP 67537

NASA Astrophysics Data System (ADS)

Jones, M. I.; Brahm, R.; Wittenmyer, R. A.; Drass, H.; Jenkins, J. S.; Melo, C. H. F.; Vos, J.; Rojo, P.

2017-06-01

We report the discovery of a substellar companion around the giant star HIP 67537. Based on precision radial velocity measurements from CHIRON and FEROS high-resolution spectroscopic data, we derived the following orbital elements for HIP 67537 b: mb sin I = 11.1+0.4-1.1Mjup, a =4.9+0.14-0.13 AU and e = 0.59+0.05-0.02 . Considering random inclination angles, this object has ≳65% probability to be above the theoretical deuterium-burning limit, thus it is one of the few known objects in the planet to brown-dwarf (BD) transition region. In addition, we analyzed the Hipparcos astrometric data of this star, from which we derived a minimum inclination angle for the companion of 2 deg. This value corresponds to an upper mass limit of 0.3 M⊙, therefore the probability that HIP 67537 b is stellar in nature is ≲7%. The large mass of the host star and the high orbital eccentricity makes HIP 67537 b a very interesting and rare substellar object. This is the second candidate companion in the brown dwarf desert detected in the sample of intermediate-mass stars targeted by the EXoPlanets aRound Evolved StarS (EXPRESS) radial velocity program, which corresponds to a detection fraction of f = +2.0-0.5 %. This value is larger than the fraction observed in solar-type stars, providing new observational evidence of an enhanced formation efficiency of massive substellar companions in massive disks. Finally, we speculate about different formation channels for this object. Based on observations collected at La Silla - Paranal Observatory under programs ID's 085.C-0557, 087.C.0476, 089.C-0524, 090.C-0345 and through the Chilean Telescope Time under programs ID's CN-12A-073, CN-12B-047, CN-13A-111, CN-2013B-51, CN-2014A-52, CN-15A-48, CN-15B-25 and CN-16A-13.

CHARACTERIZING THE BROWN DWARF FORMATION CHANNELS FROM THE INITIAL MASS FUNCTION AND BINARY-STAR DYNAMICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thies, Ingo; Pflamm-Altenburg, Jan; Kroupa, Pavel

2015-02-10

The stellar initial mass function (IMF) is a key property of stellar populations. There is growing evidence that the classical star-formation mechanism by the direct cloud fragmentation process has difficulties reproducing the observed abundance and binary properties of brown dwarfs and very-low-mass stars. In particular, recent analytical derivations of the stellar IMF exhibit a deficit of brown dwarfs compared to observational data. Here we derive the residual mass function of brown dwarfs as an empirical measure of the brown dwarf deficiency in recent star-formation models with respect to observations and show that it is compatible with the substellar part ofmore » the Thies-Kroupa IMF and the mass function obtained by numerical simulations. We conclude that the existing models may be further improved by including a substellar correction term that accounts for additional formation channels like disk or filament fragmentation. The term ''peripheral fragmentation'' is introduced here for such additional formation channels. In addition, we present an updated analytical model of stellar and substellar binarity. The resulting binary fraction and the dynamically evolved companion mass-ratio distribution are in good agreement with observational data on stellar and very-low-mass binaries in the Galactic field, in clusters, and in dynamically unprocessed groups of stars if all stars form as binaries with stellar companions. Cautionary notes are given on the proper analysis of mass functions and the companion mass-ratio distribution and the interpretation of the results. The existence of accretion disks around young brown dwarfs does not imply that these form just like stars in direct fragmentation.« less

Sonora: A New Generation Model Atmosphere Grid for Brown Dwarfs and Young Extrasolar Giant Planets

NASA Astrophysics Data System (ADS)

Marley, Mark S.; Saumon, Didier; Fortney, Jonathan J.; Morley, Caroline; Lupu, Roxana E.; Freedman, Richard; Visscher, Channon

2017-06-01

Brown dwarf and giant planet atmospheric structure and composition has been studied both by forward models and, increasingly so, by retrieval methods. While indisputably informative, retrieval methods are of greatest value when judged in the context of grid model predictions. Meanwhile retrieval models can test the assumptions inherent in the forward modeling procedure.In order to provide a new, systematic survey of brown dwarf atmospheric structure, emergent spectra, and evolution, we have constructed a new grid of brown dwarf model atmospheres. We ultimately aim for our grid to span substantial ranges of atmospheric metallilcity, C/O ratios, cloud properties, atmospheric mixing, and other parameters. Spectra predicted by our modeling grid can be compared to both observations and retrieval results to aid in the interpretation and planning of future telescopic observations.We thus present Sonora, a new generation of substellar atmosphere models, appropriate for application to studies of L, T, and Y-type brown dwarfs and young extrasolar giant planets. The models describe the expected temperature-pressure profile and emergent spectra of an atmosphere in radiative-convective equilibrium for ranges of effective temperatures and gravities encompassing 200 ≤ Teff ≤ 2400 K and 2.5 ≤ log g ≤ 5.5. In our poster we briefly describe our modeling methodology, enumerate various updates since our group's previous models, and present our initial tranche of models for cloudless, solar metallicity, and solar carbon-to-oxygen ratio, chemical equilibrium atmospheres. These models will be available online and will be updated as opacities and cloud modeling methods continue to improve.

A Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf "Lithium Test" at Early Ages

NASA Astrophysics Data System (ADS)

Kirkpatrick, J. Davy; Cruz, Kelle L.; Barman, Travis S.; Burgasser, Adam J.; Looper, Dagny L.; Tinney, C. G.; Gelino, Christopher R.; Lowrance, Patrick J.; Liebert, James; Carpenter, John M.; Hillenbrand, Lynne A.; Stauffer, John R.

2008-12-01

Using a large sample of optical spectra of late-type dwarfs, we identify a subset of late-M through L field dwarfs that, because of the presence of low-gravity features in their spectra, are believed to be unusually young. From a combined sample of 303 field L dwarfs, we find observationally that 7.6% +/- 1.6% are younger than 100 Myr. This percentage is in agreement with theoretical predictions once observing biases are taken into account. We find that these young L dwarfs tend to fall in the southern hemisphere (decl . < 0°) and may be previously unrecognized, low-mass members of nearby, young associations like Tucana-Horologium, TW Hydrae, β Pictoris, and AB Doradus. We use a homogeneously observed sample of ~150 optical spectra to examine lithium strength as a function of L/T spectral type and further corroborate the trends noted by Kirkpatrick and coworkers. We use our low-gravity spectra to investigate lithium strength as a function of age. The data weakly suggest that for early- to mid-L dwarfs the line strength reaches a maximum for a few × 100 Myr, whereas for much older (few Gyr) and much younger (<100 Myr) L dwarfs the line is weaker or undetectable. We show that a weakening of lithium at lower gravities is predicted by model atmosphere calculations, an effect partially corroborated by existing observational data. Larger samples containing L dwarfs of well-determined ages are needed to further test this empirically. If verified, this result would reinforce the caveat first cited by Kirkpatrick and coworkers that the lithium test should be used with caution when attempting to confirm the substellar nature of the youngest brown dwarfs. Most of the spectroscopic data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous

Looking for high-mass young stellar objects: H2O and OH masers in ammonia cores

NASA Astrophysics Data System (ADS)

Codella, C.; Cesaroni, R.; López-Sepulcre, A.; Beltrán, M. T.; Furuya, R.; Testi, L.

2010-02-01

Context. The earliest stages of high-mass star formation have yet to be characterised well, because high-angular resolution observations are required to infer the properties of the molecular gas hosting the newly formed stars. Aims: We search for high-mass molecular cores in a large sample of 15 high-mass star-forming regions that are observed at high-angular resolution, extending a pilot survey based on a smaller number of objects. Methods: The sample was chosen from surveys of H2O and OH masers to favour the earliest phases of high-mass star formation. Each source was first observed with the 32-m single-dish Medicina antenna in the (1, 1) and (2, 2) inversion transitions at 1.3 cm of ammonia, which is an excellent tracer of dense gas. High-resolution maps in the NH3(2, 2) and (3, 3) lines and the 1.3 cm continuum were obtained successively with the VLA interferometer. Results: We detect continuum emission in almost all the observed star-forming regions, which corresponds to extended and UCHii regions created by young stellar objects with typical luminosities of ˜10^4~L⊙. However, only in three cases do we find a projected overlap between Hii regions and H2O and OH maser spots. On the other hand, the VLA images detect eight ammonia cores closely associated with the maser sources. The ammonia cores have sizes of ˜10^4 AU, and high masses (up to 104M⊙), and are very dense (from ˜10^6 to a few ×10^9 cm-3). The typical relative NH3 abundance is ≤10-7, in agreement with previous measurements in high-mass star-forming regions. Conclusions: The statistical analysis of the distribution between H2O and OH masers, NH3 cores, and Hii regions confirms that the earliest stages of high-mass star formation are characterised by high-density molecular cores with temperatures of on average ≥30 K, either without a detectable ionised region or associated with a hypercompact Hii region.

Barriers to Positive Mental Health in a Young Offenders Institution: A Qualitative Study

ERIC Educational Resources Information Center

Woodall, James

2007-01-01

Objective: To explore the barriers to positive mental health in a group of young offenders. Design: A qualitative approach was used to provide insight into the ways in which mental health for young offenders is experienced and managed. Setting: A Young Offenders Institute (YOI) accommodating males aged between 18 and 21 years. Method: Participants…

Young Children's Reactions to Mothers' Disclosure of Maternal HIV+ Serostatus

ERIC Educational Resources Information Center

Murphy, Debra A.; Roberts, Kathleen J.; Hoffman, Dannie

2006-01-01

Little is known about the impact of maternal disclosure of HIV-positive serostatus on young children. The objective of this study was to explore this topic, utilizing in-depth qualitative interviews. Qualitative interviews were conducted with 47 mothers who had disclosed to their young, well child, and with the children. The most prevalent child…

Learning What to Remember: Vocabulary Knowledge and Children's Memory for Object Names and Features

ERIC Educational Resources Information Center

Perry, Lynn K.; Axelsson, Emma L.; Horst, Jessica S.

2016-01-01

Although young children can map a novel name to a novel object, it remains unclear what they actually remember about objects when they initially make such a name-object association. In the current study we investigated (1) what children remembered after they were initially introduced to name-object associations and (2) how their vocabulary size…

OBJECT REPRESENTATION, IDENTITY, AND THE PARADOX OF EARLY PERMANENCE: Steps Toward a New Framework

PubMed Central

Meltzoff, Andrew N.; Moore, M. Keith

2013-01-01

The sensorimotor theory of infancy has been overthrown, but there is little consensus on a replacement. We hypothesize that a capacity for representation is the starting point for infant development, not its culmination. Logical distinctions are drawn between object representation, identity, and permanence. Modern experiments on early object permanence and deferred imitation suggest: (a) even for young infants, representations persist over breaks in sensory contact, (b) numerical identity of objects (Os) is initially specified by spatiotemporal criteria (place and trajectory), (c) featural and functional identity criteria develop, (d) events are analyzed by comparing representations to current perception, and (e) representation operates both prospectively, anticipating future contacts with an O, and retrospectively, reidentifying an O as the “same one again.” A model of the architecture and functioning of the early representational system is proposed. It accounts for young infants’ behavior toward absent people and things in terms of their efforts to determine the identity of objects. Our proposal is developmental without denying innate structure and elevates the power of perception and representation while being cautious about attributing complex concepts to young infants. PMID:25147418

A young star takes centre stage

NASA Image and Video Library

2015-03-02

With its helical appearance resembling a snail’s shell, this reflection nebula seems to spiral out from a luminous central star in this new NASA/ESA Hubble Space Telescope image. The star in the centre, known as V1331 Cyg and located in the dark cloud LDN 981 — or, more commonly, Lynds 981 — had previously been defined as a T Tauri star. A T Tauri is a young star — or Young Stellar Object — that is starting to contract to become a main sequence star similar to the Sun. What makes V1331Cyg special is the fact that we look almost exactly at one of its poles. Usually, the view of a young star is obscured by the dust from the circumstellar disc and the envelope that surround it. However, with V1331Cyg we are actually looking in the exact direction of a jet driven by the star that is clearing the dust and giving us this magnificent view. This view provides an almost undisturbed view of the star and its immediate surroundings allowing astronomers to study it in greater detail and look for features that might suggest the formation of a verylow-mass object in the outer circumstellar disc.

Younger vampire bats (Desmodus rotundus) are more likely than adults to explore novel objects.

PubMed

Carter, Gerald G; Forss, Sofia; Page, Rachel A; Ratcliffe, John M

2018-01-01

The effects of age on neophobia and exploration are best described in birds and primates, and broader comparisons require reports from other taxa. Here we present data showing age-dependent exploration in a long-lived social species, the common vampire bat (Desmodus rotundus). A previous study found that vampire bats regurgitated food to partners trapped in a cage. Interestingly, while only a few adult bats visited the trapped bat, in every trial all or most of the eight young males in the colony would visit the trapped bat without feeding it. To test whether this behavioral difference resulted from age class differences in exploration, we compared responses of the bats to a trapped conspecific versus an inanimate novel object. Some adults and young showed interest in trapped conspecifics, but only the young males explored the novel objects. Additional novel object tests in a second captive colony showed that higher rates of novel object exploration were shown by young of both sexes. Our results corroborate past findings from other mammals and birds that age predicts exploration. If age-dependent exploration is indeed adaptive, then the role of age as a predictor of exploration tendency should depend on species-specific life history traits. Finally, because younger vampire bats also appear to have higher exposure to pathogens such as rabies virus, there may be implications for pathogen transmission if younger and more exploratory vampire bats are more likely to feed on novel hosts.

HERBIG-HARO OBJECTS IN THE LUPUS I AND III MOLECULAR CLOUDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Hongchi; Henning, Thomas

2009-10-15

We performed a deep search for Herbig-Haro (HH) objects toward the Lupus I and III clouds, covering a sky area of {approx} 1 and {approx} 0.5 deg{sup 2}, respectively. In total, 11 new HH objects, HH 981--991, are discovered. The HH objects both in Lupus I and in Lupus III tend to be concentrated in small areas. The HH objects detected in Lupus I are located in a region of radius 0.26 pc near the young star Sz 68. The abundance of HH objects shows that this region of the cloud is active in on-going star formation. HH objects inmore » the Lup III cloud are concentrated in the central part of the cloud around the Herbig Ae/Be stars HR 5999 and 6000. HH 981 and 982 in Lupus I are probably driven by the young brown dwarf SSTc2d J154457.9-342340 which has a mass of 50 M{sub J} . HH 990 and 991 in Lup III align well with the HH 600 jet emanating from the low-mass star Par-Lup3-4, and are probably excited by this low-mass star of spectral type M5. High proper motions for HH 228 W, E, and E2 are measured, which confirms that they are excited by the young star Th 28. In contrast, HH 78 exhibits no measurable proper motion in the time span of 18 years, indicating that HH 78 is unlikely part of the HH 228 flow. The HH objects in Lup I and III are generally weak in terms of brightness and dimension in comparison to HH objects we detected with the same technique in the R CrA and Cha I clouds. Through a comparison with the survey results from the Spitzer c2d program, we find that our optical survey is more sensitive, in terms of detection rate, than the Spitzer IRAC survey to high-velocity outflows in the Lup I and III clouds.« less

Infants' use of category knowledge and object attributes when segregating objects at 8.5 months of age.

PubMed

Needham, Amy; Cantlon, Jessica F; Ormsbee Holley, Susan M

2006-12-01

The current research investigates infants' perception of a novel object from a category that is familiar to young infants: key rings. We ask whether experiences obtained outside the lab would allow young infants to parse the visible portions of a partly occluded key ring display into one single unit, presumably as a result of having categorized it as a key ring. This categorization was marked by infants' perception of the keys and ring as a single unit that should move together, despite their attribute differences. We showed infants a novel key ring display in which the keys and ring moved together as one rigid unit (Move-together event) or the ring moved but the keys remained stationary throughout the event (Move-apart event). Our results showed that 8.5-month-old infants perceived the keys and ring as connected despite their attribute differences, and that their perception of object unity was eliminated as the distinctive attributes of the key ring were removed. When all of the distinctive attributes of the key ring were removed, the 8.5-month-old infants perceived the display as two separate units, which is how younger infants (7-month-old) perceived the key ring display with all its distinctive attributes unaltered. These results suggest that on the basis of extensive experience with an object category, infants come to identify novel members of that category and expect them to possess the attributes typical of that category.

Massive Young Stellar Objects in the Galactic Center. 1; Spectroscopic Identification from Spitzer/IRS Observations

NASA Technical Reports Server (NTRS)

An, Deokkeun; Ramirez, Solange V.; Sellgren, Kris; Arendt, Richard G.; Boogert, A. C. Adwin; Robitaille, Thomas P.; Schultheis, Mathias; Cotera, Angela S.; Smith, Howard A.; Stolovy, Susan R.

2011-01-01

We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in the Galactic Center (GC). Our sample of 107 YSO candidates was selected based on IRAC colors from the high spatial resolution, high sensitivity Spitzer/IRAC images in the Central Molecular Zone (CMZ), which spans the central approximately 300 pc region of the Milky Way Galaxy. We obtained IRS spectra over 5 micron to 35 micron using both high- and low-resolution IRS modules. We spectroscopically identify massive YSOs by the presence of a 15.4 micron shoulder on the absorption profile of 15 micron CO2 ice, suggestive of CO2 ice mixed with CH30H ice on grains. This 15.4 micron shoulder is clearly observed in 16 sources and possibly observed in an additional 19 sources. We show that 9 massive YSOs also reveal molecular gas-phase absorption from C02, C2H2, and/or HCN, which traces warm and dense gas in YSOs. Our results provide the first spectroscopic census of the massive YSO population in the GC. We fit YSO models to the observed spectral energy distributions and find YSO masses of 8 - 23 solar Mass, which generally agree with the masses derived from observed radio continuum emission. We find that about 50% of photometrically identified YSOs are confirmed with our spectroscopic study. This implies a preliminary star formation rate of approximately 0.07 solar mass/yr at the GC.

Mother-Child Communication about Location: Giving and Following Directions for Finding Hidden Objects

ERIC Educational Resources Information Center

Plumert, Jodie M.; Haggerty, Kathryn A.; Mickunas, Andrew; Herzog, Lauren; Shadrick, Courtney

2012-01-01

We conducted 2 experiments to examine how mothers structure directions to young children for finding hidden objects and how young children use these directions to guide their searches. In Experiment 1, we examined the reference frames mothers use to communicate with their 2.5-, 3-, and 3.5-year-old children about location by asking mothers to…

Young Children's Understanding of Violations of Property Rights

ERIC Educational Resources Information Center

Rossano, Federico; Rakoczy, Hannes; Tomasello, Michael

2011-01-01

The present work investigated young children's normative understanding of property rights using a novel methodology. Two- and 3-year-old children participated in situations in which an actor (1) took possession of an object for himself, and (2) attempted to throw it away. What varied was who owned the object: the actor himself, the child subject,…

The first X-ray emitting brown dwarf.

NASA Astrophysics Data System (ADS)

Comerón, F.; Neuhäuser, R.; Kaas, A. A.

1998-12-01

The increasing number of brown dwarfs discovered in the last few years is rapidly opening the possibilities of studying a wide range of their properties and the ways in which these depend on essential parameters, such as the mass, the age, the rotation, or the environment. One of these properties is the magnetic field, which in principle should be expected to be important in fully convective objects such as brown dwarfs. The chromospheric X-ray emission, widely observed in M-type dwarfs (Neuhäuser 1997), has its origin in this magnetic activity. As such, it offers an observational tool to probe the interior of these objects, the mechanisms for the generation and maintenance of their magnetic fields, and the way in which the magnetic activity is affected by the basic parameters of the object. The detection of X-ray emission from brown dwarfs is thus of great importance to extend our understanding of the properties of stellar magnetic fields to the substellar domain, as well as to ascertain to what extent a small, substellar mass, and the consequent lack of a permanent nuclear energy source, can have an impact in the production and the evolution of a magnetic field.

Will Any Doll Do? 12-Month-Olds' Reasoning about Goal Objects

ERIC Educational Resources Information Center

Spaepen, Elizabet; Spelke, Elizabeth

2007-01-01

Infants as young as 5 months of age view familiar actions such as reaching as goal-directed (Woodward, 1998), but how do they construe the goal of an actor's reach? Six experiments investigated whether 12-month-old infants represent reaching actions as directed to a particular individual object, to a narrowly defined object category (e.g., an…

Connection-based and object-based grouping in multiple-object tracking: A developmental study.

PubMed

Van der Hallen, Ruth; Reusens, Julie; Evers, Kris; de-Wit, Lee; Wagemans, Johan

2018-03-30

Developmental research on Gestalt laws has previously revealed that, even as young as infancy, we are bound to group visual elements into unitary structures in accordance with a variety of organizational principles. Here, we focus on the developmental trajectory of both connection-based and object-based grouping, and investigate their impact on object formation in participants, aged 9-21 years old (N = 113), using a multiple-object tracking paradigm. Results reveal a main effect of both age and grouping type, indicating that 9- to 21-year-olds are sensitive to both connection-based and object-based grouping interference, and tracking ability increases with age. In addition to its importance for typical development, these results provide an informative baseline to understand clinical aberrations in this regard. Statement of contribution What is already known on this subject? The origin of the Gestalt principles is still an ongoing debate: Are they innate, learned over time, or both? Developmental research has revealed how each Gestalt principle has its own trajectory and unique relationship to visual experience. Both connectedness and object-based grouping play an important role in object formation during childhood. What does this study add? The study identifies how sensitivity to connectedness and object-based grouping evolves in individuals, aged 9-21 years old. Using multiple-object tracking, results reveal that the ability to track multiple objects increases with age. These results provide an informative baseline to understand clinical aberrations in different types of grouping. © 2018 The Authors. British Journal of Developmental Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norris, Jackson M.; Wright, Jason T.; Mahadevan, Suvrath

It has been argued that a substellar companion may significantly influence the evolution of the progenitors of subdwarf B (sdB) stars. Recently, the bright sdB star HD 149382 has been claimed to host a substellar (possibly planetary) companion with a period of 2.391 days. This has important implications for the evolution of the progenitors of sdB stars as well as the source of the UV excess seen in elliptical galaxies. In order to verify this putative companion, we made 10 radial velocity measurements of HD 149382 over 17 days with the High Resolution Spectrograph at the Hobby-Eberly Telescope. Our datamore » conclusively demonstrate that the putative substellar companion does not exist, and they exclude the presence of almost any substellar companion with P < 28 days and Msin i {approx}> 1 M{sub Jup}.« less

Key health outcomes for children and young people with neurodisability: qualitative research with young people and parents

PubMed Central

Allard, Amanda; Fellowes, Andrew; Shilling, Valerie; Janssens, Astrid; Beresford, Bryony; Morris, Christopher

2014-01-01

Objectives To identify key health outcomes, beyond morbidity and mortality, regarded as important in children and young people with neurodisability, and their parents. Design Qualitative research incorporating a thematic analysis of the data supported by the Framework Approach; the International Classification of Functioning, Disability and Health (ICF) provided a theoretical foundation. Setting The study was conducted in community settings. Participants Participants were 54 children and young people with neurodisability: 50 participated in focus groups, and 4 in interviews; 53 parents participated: 47 in focus groups and 6 in interviews. Children/young people and parents were recruited through different networks, and were not related. Results Children/young people and parents viewed health outcomes as inter-related. Achievement in some outcomes appeared valued to the extent that it enabled or supported more valued domains of health. Health outcomes prioritised by both young people and parents were: communication, mobility, pain, self-care, temperament, interpersonal relationships and interactions, community and social life, emotional well-being and gaining independence/future aspirations. Parents also highlighted their child's sleep, behaviour and/or safety. Conclusions Those responsible for health services for children/young people with neurodisability should take account of the aspects of health identified by families. The aspects of health identified in this study provide a basis for selecting appropriate health indicators and outcome measures. PMID:24747792

Planets around Low-mass Stars (PALMS). VI. Discovery of a Remarkably Red Planetary-mass Companion to the AB Dor Moving Group Candidate 2MASS J22362452+4751425*

NASA Astrophysics Data System (ADS)

Bowler, Brendan P.; Liu, Michael C.; Mawet, Dimitri; Ngo, Henry; Malo, Lison; Mace, Gregory N.; McLane, Jacob N.; Lu, Jessica R.; Tristan, Isaiah I.; Hinkley, Sasha; Hillenbrand, Lynne A.; Shkolnik, Evgenya L.; Benneke, Björn; Best, William M. J.

2017-01-01

We report the discovery of an extremely red planetary-mass companion to 2MASS J22362452+4751425, a ≈0.6 M⊙ late-K dwarf likely belonging to the ˜120 Myr AB Doradus moving group. 2M2236+4751 b was identified in multi-epoch NIRC2 adaptive optics imaging at Keck Observatory at a separation of 3\\buildrel{\\prime\\prime}\\over{.} 7, or 230 ± 20 AU in projection at the kinematic distance of 63 ± 5 pc to its host star. Assuming membership in the AB Dor group, as suggested from its kinematics, the inferred mass of 2M2236+4751 b is 11-14 MJup. Follow-up Keck/OSIRIS K-band spectroscopy of the companion reveals strong CO absorption similar to other faint red L dwarfs and lacks signs of methane absorption, despite having an effective temperature of ≈900-1200 K. With a (J-K)MKO color of 2.69 ± 0.12 mag, the near-infrared slope of 2M2236+4751 b is redder than all of the HR 8799 planets and instead resembles the ≈23 Myr isolated planetary-mass object PSO J318.5-22, implying that similarly thick photospheric clouds can persist in the atmospheres of giant planets at ages beyond 100 Myr. In near-infrared color-magnitude diagrams, 2M2236+4751 b is located at the tip of the red L dwarf sequence and appears to define the “elbow” of the AB Dor substellar isochrone separating low-gravity L dwarfs from the cooler young T dwarf track. 2M2236+4751 b is the reddest substellar companion to a star and will be a valuable benchmark to study the shared atmospheric properties of young low-mass brown dwarfs and extrasolar giant planets. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

Young adult smoking behavior: a national survey.

PubMed

Ling, Pamela M; Neilands, Torsten B; Glantz, Stanton A

2009-05-01

Young adults have the highest smoking rate of any age group in the U.S., and new strategies to decrease young adult smoking are needed. The objective of the current study was to identify psychographic and demographic factors associated with current smoking and quitting behaviors among young adults. Attitudes, social groups, and self-descriptors, including supporting action against the tobacco industry, advertising receptivity, depression, alcohol use, and other factors associated with smoking were tested for associations with smoking behaviors in a 2005 cross-sectional survey of 1528 young adults (aged 18-25 years) from a web-enabled panel. Analyses were conducted in 2007. Being older was associated with current smoking, whereas having some higher education and being African American or Hispanic were negatively associated with smoking. Supporting action against the tobacco industry was negatively associated with smoking (AOR=0.34 [95% CI=0.22, 0.52]). Perceived usefulness of smoking, exposure to smokers, increased perceived smoking prevalence, receptivity to tobacco advertising, binge drinking, and exposure to tobacco advertising in bars and clubs were associated with smoking. Supporting action against the tobacco industry was associated with intentions to quit smoking (AOR=4.43 [95% CI=2.18, 8.60]). Young adults are vulnerable to tobacco-industry advertising. Media campaigns that denormalize the tobacco industry and appeal to young adults appear to be a powerful intervention to decrease young adult smoking.

Shaking things up: Young infants' use of sound information for object individuation

PubMed Central

wilcox, Teresa

2013-01-01

A search task was used to assess 5- to 7-month-olds' ability to use property-rich sounds to individuate objects. Results suggest that infants interpret an occlusion event involving two distinct rattle sounds as involving two objects but are unsure of how to interpret two identical rattle sounds. PMID:22306182

Young Children Follow Pointing over Words in Interpreting Acts of Reference

ERIC Educational Resources Information Center

Grassmann, Susanne; Tomasello, Michael

2010-01-01

Adults refer young children's attention to things in two basic ways: through the use of pointing (and other deictic gestures) and words (and other linguistic conventions). In the current studies, we referred young children (2- and 4-year-olds) to things in conflicting ways, that is, by pointing to one object while indicating linguistically (in…

Herschel Observations of Protostellar and Young Stellar Objects in Nearby Molecular Clouds: The DIGIT Open Time Key Project

NASA Astrophysics Data System (ADS)

Green, Joel D.; DIGIT OTKP Team

2010-01-01

The DIGIT (Dust, Ice, and Gas In Time) Open Time Key Project utilizes the PACS spectrometer (57-210 um) onboard the Herschel Space Observatory to study the colder regions of young stellar objects and protostellar cores, complementary to recent observations from Spitzer and ground-based observatories. DIGIT focuses on 30 embedded sources and 64 disk sources, and includes supporting photometry from PACS and SPIRE, as well as spectroscopy from HIFI, selected from nearby molecular clouds. For the embedded sources, PACS spectroscopy will allow us to address the origin of [CI] and high-J CO lines observed with ISO-LWS. Our observations are sensitive to the presence of cold crystalline water ice, diopside, and carbonates. Additionally, PACS scans are 5x5 maps of the embedded sources and their outflows. Observations of more evolved disk sources will sample low and intermediate mass objects as well as a variety of spectral types from A to M. Many of these sources are extremely rich in mid-IR crystalline dust features, enabling us to test whether similar features can be detected at larger radii, via colder dust emission at longer wavelengths. If processed grains are present only in the inner disk (in the case of full disks) or from the emitting wall surface which marks the outer edge of the gap (in the case of transitional disks), there must be short timescales for dust processing; if processed grains are detected in the outer disk, radial transport must be rapid and efficient. Weak bands of forsterite and clino- and ortho-enstatite in the 60-75 um range provide information about the conditions under which these materials were formed. For the Science Demonstration Phase we are observing an embedded protostar (DK Cha) and a Herbig Ae/Be star (HD 100546), exemplars of the kind of science that DIGIT will achieve over the full program.

Low-Income Mothers' Food Practices with Young Children: A Qualitative Longitudinal Study

ERIC Educational Resources Information Center

Harden, Jeni; Dickson, Adele

2015-01-01

Objective: Young children living in socioeconomically deprived areas of Scotland have an increased risk of becoming overweight or obese. To enhance understanding of the wider contexts within which family food practices are developed, this study examined the experiences of low-income mothers with young children. Design: Qualitative longitudinal…

Young Adult Outcome of Hyperactive Children: Adaptive Functioning in Major Life Activities

ERIC Educational Resources Information Center

Barkley, Russell A.; Fischer, Mariellen; Smallish, Lori; Fletcher, Kenneth

2006-01-01

Objective: The authors report the adaptive functioning of hyperactive and control children in southeastern Wisconsin (Milwaukee) followed to young adulthood. Method: Interviews with participants concerning major life activities were collected between 1992 and 1996 and used along with employer ratings and high school records at the young adult…

Extreme Radio Flares and Associated X-Ray Variability from Young Stellar Objects in the Orion Nebula Cluster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forbrich, Jan; Reid, Mark J.; Wolk, Scott J.

Young stellar objects are known to exhibit strong radio variability on timescales of weeks to months, and a few reports have documented extreme radio flares with at least an order of magnitude change in flux density on timescales of hours to days. However, there have been few constraints on the occurrence rate of such radio flares or on the correlation with pre-main sequence X-ray flares, although such correlations are known for the Sun and nearby active stars. Here we report simultaneous deep VLA radio and Chandra X-ray observations of the Orion Nebula Cluster, targeting hundreds of sources to look formore » the occurrence rate of extreme radio variability and potential correlation with the most extreme X-ray variability. We identify 13 radio sources with extreme radio variability, with some showing an order of magnitude change in flux density in less than 30 minutes. All of these sources show X-ray emission and variability, but we find clear correlations with extreme radio flaring only on timescales <1 hr. Strong X-ray variability does not predict the extreme radio sources and vice versa. Radio flares thus provide us with a new perspective on high-energy processes in YSOs and the irradiation of their protoplanetary disks. Finally, our results highlight implications for interferometric imaging of sources violating the constant-sky assumption.« less

FREQUENCY OF MOUTHING BEHAVIOR IN YOUNG CHILDREN

EPA Science Inventory

Young children may be more likely than adults to be exposed to pesticides following a residential application as a result of hand- and object-to-mouth contacts in contaminated areas. However, relatively few studies have specifically evaluated mouthing behavior in children less ...

FREQUENCY OF MOUTHING BEHAVIOR IN YOUNG CHILDREN

EPA Science Inventory

Young children, as compared to adults, are more likely to be exposed after a pesticide application due to potential hand- and object-to-mouth contacts in contaminated areas. However, relatively few studies have specifically evaluated mouthing behavior in children <60 months of...

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Michael C.; Dupuy, Trent J.; Leggett, S. K., E-mail: mliu@ifa.hawaii.ed

Highly unequal-mass ratio binaries are rare among field brown dwarfs, with the mass ratio distribution of the known census described by q {sup (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 {epsilon} Ind Bab binary and a newly discovered 0.''14 T2.0 + T7.5 binary, 2MASS J12095613-1004008AB, identified with Keck laser guide star adaptive optics. The latter is the mostmore » extreme tight binary resolved to date (q {approx} 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{sup +1.2}{sub -1.3}) dex and 0.5{sup +0.4}{sub -0.3}(0.3{sup +0.3}{sub -0.4}) dex for 2MASS J1209-1004AB and {epsilon} Ind Bab, respectively, as inferred from the Lyon (Tucson) models. However, the total mass of {epsilon} Ind Bab derived from the H-R diagram ({approx} 80 M{sub Jup} using the Lyon models) is strongly discrepant with the reported dynamical mass. This problem, which is independent of the assumed age of the {epsilon} Ind Bab system, can be explained by a {approx} 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 {approx} 6 Gyr for {epsilon} 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 ({approx}100 K) errors in the evolutionary models and/or model atmospheres, but not significantly larger. Future parallax, resolved

Spectral Characteristics of Young Stars Associated with the Sh2-296 Nebula

NASA Astrophysics Data System (ADS)

Fernandes, Beatriz; Gregorio-Hetem, Jane

Aiming to contribute to the understanding of star formation and evolution in the Canis Major (CMa R1) Molecular Clouds Complex, we analyze the spectral characteristics of a population of young stars associated with the arc-shaped nebula Sh2-296. Our XMM/Newton observations detected 109 X-ray sources in the region and optical spectroscopy was performed with Gemini telescope for 85 optical counterparts. We identified and characterized 51 objects that present features typically found in young objects, such as Hα emission and strong absorption on the Li I line.

Impact of age-related macular degeneration on object searches in realistic panoramic scenes.

PubMed

Thibaut, Miguel; Tran, Thi-Ha-Chau; Szaffarczyk, Sebastien; Boucart, Muriel

2018-05-01

This study investigated whether realistic immersive conditions with dynamic indoor scenes presented on a large, hemispheric panoramic screen covering 180° of the visual field improved the visual search abilities of participants with age-related macular degeneration (AMD). Twenty-one participants with AMD, 16 age-matched controls and 16 young observers were included. Realistic indoor scenes were presented on a panoramic five metre diameter screen. Twelve different objects were used as targets. The participants were asked to search for a target object, shown on paper before each trial, within a room composed of various objects. A joystick was used for navigation within the scene views. A target object was present in 24 trials and absent in 24 trials. The percentage of correct detection of the target, the percentage of false alarms (that is, the detection of the target when it was absent), the number of scene views explored and the search time were measured. The search time was slower for participants with AMD than for the age-matched controls, who in turn were slower than the young participants. The participants with AMD were able to accomplish the task with a performance of 75 per cent correct detections. This was slightly lower than older controls (79.2 per cent) while young controls were at ceiling (91.7 per cent). Errors were mainly due to false alarms resulting from confusion between the target object and another object present in the scene in the target-absent trials. The outcomes of the present study indicate that, under realistic conditions, although slower than age-matched, normally sighted controls, participants with AMD were able to accomplish visual searches of objects with high accuracy. © 2017 Optometry Australia.

Conflict between object structural and functional affordances in peripersonal space.

PubMed

Kalénine, Solène; Wamain, Yannick; Decroix, Jérémy; Coello, Yann

2016-10-01

Recent studies indicate that competition between conflicting action representations slows down planning of object-directed actions. The present study aims to assess whether similar conflict effects exist during manipulable object perception. Twenty-six young adults performed reach-to-grasp and semantic judgements on conflictual objects (with competing structural and functional gestures) and non-conflictual objects (with similar structural and functional gestures) presented at difference distances in a 3D virtual environment. Results highlight a space-dependent conflict between structural and functional affordances. Perceptual judgments on conflictual objects were slower that perceptual judgments on non-conflictual objects, but only when objects were presented within reach. Findings demonstrate that competition between structural and functional affordances during object perception induces a processing cost, and further show that object position in space can bias affordance competition. Copyright © 2016 Elsevier B.V. All rights reserved.

A motivation-based explanatory model of street drinking among young people.

PubMed

Martín-Santana, Josefa D; Beerli-Palacio, Asunción; Fernández-Monroy, Margarita

2014-01-01

This social marketing study focuses on street drinking behavior among young people. The objective is to divide the market of young people who engage in this activity into segments according to their motivations. For the three segments identified, a behavior model is created using the beliefs, attitudes, behavior, and social belonging of young people who engage in street drinking. The methodology used individual questionnaires filled in by a representative sample of young people. The results show that the behavior model follows the sequence of attitudes-beliefs-behavior and that social belonging influences these three variables. Similarly, differences are observed in the behavior model depending on the segment individuals belong to.

Children's use of comparison and function in novel object categorization.

PubMed

Kimura, Katherine; Hunley, Samuel B; Namy, Laura L

2018-06-01

Although young children often rely on salient perceptual cues, such as shape, when categorizing novel objects, children eventually shift towards deeper relational reasoning about category membership. This study investigates what information young children use to classify novel instances of familiar categories. Specifically, we investigated two sources of information that have the potential to facilitate the classification of novel exemplars: (1) comparison of familiar category instances, and (2) attention to function information that might direct children's attention to functionally relevant perceptual features. Across two experiments, we found that comparing two perceptually similar category members-particularly when function information was also highlighted-led children to discover non-obvious relational features that supported their categorization of novel category instances. Together, these findings demonstrate that comparison may aid in novel object categorization by heightening the salience of less obvious, yet functionally relevant, relational structures that support conceptual reasoning. Copyright © 2018. Published by Elsevier Inc.

Direct Object Predictability: Effects on Young Children's Imitation of Sentences

ERIC Educational Resources Information Center

Valian, Virginia; Prasada, Sandeep; Scarpa, Jodi

2006-01-01

We hypothesize that the conceptual relation between a verb and its direct object can make a sentence easier ("the cat is eating some food") or harder ("the cat is eating a sock") to parse and understand. If children's limited performance systems contribute to the ungrammatical brevity of their speech, they should perform better on sentences that…

Sonora: A New Generation Model Atmosphere Grid for Brown Dwarfs and Young Extrasolar Giant Planets

NASA Technical Reports Server (NTRS)

Marley, Mark S.; Saumon, Didier; Fortney, Jonathan J.; Morley, Caroline; Lupu, Roxana Elena; Freedman, Richard; Visscher, Channon

2017-01-01

Brown dwarf and giant planet atmospheric structure and composition has been studied both by forward models and, increasingly so, by retrieval methods. While indisputably informative, retrieval methods are of greatest value when judged in the context of grid model predictions. Meanwhile retrieval models can test the assumptions inherent in the forward modeling procedure. In order to provide a new, systematic survey of brown dwarf atmospheric structure, emergent spectra, and evolution, we have constructed a new grid of brown dwarf model atmospheres. We ultimately aim for our grid to span substantial ranges of atmospheric metallilcity, C/O ratios, cloud properties, atmospheric mixing, and other parameters. Spectra predicted by our modeling grid can be compared to both observations and retrieval results to aid in the interpretation and planning of future telescopic observations. We thus present Sonora, a new generation of substellar atmosphere models, appropriate for application to studies of L, T, and Y-type brown dwarfs and young extrasolar giant planets. The models describe the expected temperature-pressure profile and emergent spectra of an atmosphere in radiative-convective equilibrium for ranges of effective temperatures and gravities encompassing 200 less than or equal to T(sub eff) less than or equal to 2400 K and 2.5 less than or equal to log g less than or equal to 5.5. In our poster we briefly describe our modeling methodology, enumerate various updates since our group's previous models, and present our initial tranche of models for cloudless, solar metallicity, and solar carbon-to-oxygen ratio, chemical equilibrium atmospheres. These models will be available online and will be updated as opacities and cloud modeling methods continue to improve.

Narrative Writing Competence and Internal State Terms of Young Adults Clinically Diagnosed with Childhood Attention Deficit Hyperactivity Disorder

ERIC Educational Resources Information Center

Miranda, Ana; Baixauli, Inmaculada; Colomer, Carla

2013-01-01

Objective: The first objective of this study was to compare the written expression competence of young adults with attention deficit hyperactivity disorder (ADHD) with that of young adults without ADHD on three types of measures: indicators of the story's microstructure with regard to productivity and morphosyntax; indicators of the macrostructure…

Is There a Substellar Object Orbiting the Solar-like Stable Contact Binary V2284 Cyg?

NASA Astrophysics Data System (ADS)

Wang, J.-J.; Jiang, L.-Q.; Zhang, B.; Zhao, S.-Q.; Yu, J.

2017-12-01

V2284 Cyg is a neglected W UMa-type binary star for photometric investigations. Monitored by the Kepler Space Telescope from 2009 to 2013, its light curves are continuously stable, suggesting that both components are inactive during this time interval. Based on the short-cadence observations, we determined the photometric solutions by using the 2013 version of the Wilson-Devinney code. These parameters reveal that V2284 Cyg is a W-type system with a degree of contact factor of f = 39.23% and a mass ratio of q = 2.90. Meanwhile, hundreds of times of minimum light were obtained and applied to analyze the orbital period changes. In the O-C diagram, a small-amplitude cyclic oscillation (A 3 = 0.00030 days and T 3 = 2.06 years) superimposed on a secular decreasing was found. The continuous decreasing may be a result from the mass transfer from the more massive component to the less massive one. With the long-term decreasing of the orbital period, this binary will evolve into a deeper contact system. Because the light curve is stable, the cyclic variation is plausibly explained as the light-travel time effect (LTTE) due to the presence of an additional body. The mass of the companion is {M}3\\sin i\\prime =0.036(+/- 0.003) {M}⊙ . If the orbital plane inclination is a random distribution, it is a brown dwarf with 66.7% probability. Therefore, the companion of V2284 Cyg is possibly the first candidate of the brown dwarf orbiting around contact binary, where both component are sharing a common convective envelope.

VizieR Online Data Catalog: SONYC census of substellar objects in Lupus 3 (Muzic+, 2014)

NASA Astrophysics Data System (ADS)

Muzic, K.; Scholz, A.; Geers, V. C.; Jayawardhana, R.; Lopez Marti, B.

2017-06-01

The near-infrared observations were designed to provide J- and KS photometry in the area slightly larger than the one covered with MOSAIC-II. We used NEWFIRM at the CTIO 4 m telescope, providing an FOV of 28'x28' and a pixel scale of 0.4". The NEWFIRM detector is a mosaic of four 2048x2048 Orion InSb arrays, organized in a 2x2 grid. Data reduction was performed using the NEWFIRM pipeline. The data were dark- and sky-subtracted and were corrected for bad pixels and flat-field effects. The astrometry was calibrated with respect to the 2MASS (Skrutskie et al. 2006AJ....131.1163S, Cat. VII/233) coordinate system, and each detector quadrant was re-projected onto an undistorted celestial tangent plane. (3 data files).

Nine-month-old infants generalize object labels, but not object preferences across individuals.

PubMed

Henderson, Annette M E; Woodward, Amanda L

2012-09-01

As with all culturally relevant human behaviours, words are meaningful because they are shared by the members of a community. This research investigates whether 9-month-old infants understand this fundamental fact about language. Experiment 1 examined whether infants who are trained on, and subsequently habituated to, a new word-referent link expect the link to be consistent across a second speaker. Experiment 2 examined whether 9-month-old infants distinguish between behaviours that are shared across individuals (i.e. words) from those that are not (i.e. object preferences). The present findings indicate that infants as young as 9 months of age expect new word-referent links, but not object preferences, to be consistent across individuals. Thus, by 9 months, infants have identified at least one of the aspects of human behaviour that is shared across individuals within a community. The implications for children's acquisition of language and culture are discussed. © 2012 Blackwell Publishing Ltd.

Nine-month-old infants generalize object labels, but not object preferences across individuals

PubMed Central

Woodward, Amanda L.

2012-01-01

As with all culturally relevant human behaviours, words are meaningful because they are shared by the members of a community. This research investigates whether 9-month-old infants understand this fundamental fact about language. Experiment 1 examined whether infants who are trained on, and subsequently habituated to, a new word-referent link expect the link to be consistent across a second speaker. Experiment 2 examined whether 9-month-old infants distinguish between behaviours that are shared across individuals (i.e., words) from those that are not (i.e., object preferences). The present findings indicate that infants as young as 9 months of age expect new word-referent links, but not object preferences, to be consistent across individuals. Thus, by 9 months, infants have identified at least one of the aspects of human behaviour that is shared across individuals within a community. The implications for children’s acquisition of language and culture are discussed. PMID:22925512

Objective Sleep in Pediatric Anxiety Disorders and Major Depressive Disorder

ERIC Educational Resources Information Center

Forbes, Erika E.; Bertocci, Michele A.; Gregory, Alice M.; Ryan, Neal D.; Axelson, David A.; Birmaher, Boris; Dahl, Ronald E.

2008-01-01

A study to examine sleep problems encountered in anxiety and depressive disorders among children and adolescents is conducted. Results indicated subjective and objective sleep problems in children and adolescents with anxiety disorders and need to be kept in mind when treating young anxious people.

Precise Ages for the Benchmark Brown Dwarfs HD 19467 B and HD 4747 B

NASA Astrophysics Data System (ADS)

Wood, Charlotte; Boyajian, Tabetha; Crepp, Justin; von Braun, Kaspar; Brewer, John; Schaefer, Gail; Adams, Arthur; White, Tim

2018-01-01

Large uncertainty in the age of brown dwarfs, stemming from a mass-age degeneracy, makes it difficult to constrain substellar evolutionary models. To break the degeneracy, we need ''benchmark" brown dwarfs (found in binary systems) whose ages can be determined independent of their masses. HD~19467~B and HD~4747~B are two benchmark brown dwarfs detected through the TRENDS (TaRgeting bENchmark objects with Doppler Spectroscopy) high-contrast imaging program for which we have dynamical mass measurements. To constrain their ages independently through isochronal analysis, we measured the radii of the host stars with interferometry using the Center for High Angular Resolution Astronomy (CHARA) Array. Assuming the brown dwarfs have the same ages as their host stars, we use these results to distinguish between several substellar evolutionary models. In this poster, we present new age estimates for HD~19467 and HD~4747 that are more accurate and precise and show our preliminary comparisons to cooling models.

Proactive coping and gambling disorder among young men.

PubMed

Sleczka, Pawel; Braun, Barbara; Grüne, Bettina; Bühringer, Gerhard; Kraus, Ludwig

2016-12-01

Objectives Male sex, young age, and frequent gambling are considered as risk factors for gambling disorder (GD) and stress might be one of the triggers of gambling behavior among problem gamblers. Conversely, well-developed coping with stress might counteract gambling problems. The Proactive Coping Theory provides a promising approach for the further development of preventive and treatment measures. The objective of the study was to investigate different facets of proactive coping (PC) in young male gamblers. Methods Young men from Bavaria were recruited via the Munich citizens' registry (n = 2,588) and Facebook invitations (n = 105). In total, 173 out of 398 individuals were positively screened for frequent gambling and/or signs of related problems and completed the baseline questionnaire of the Munich Leisure-time Study. Factors investigated include gambling problems, PC, impulsiveness, social support, and psychological distress. Results Gambling problems were associated with lower levels of preventive coping as well as of adaptive reaction delay. The associations were also significant when controlled for impulsiveness and general psychological distress. Preventive coping moderated the association between social support and gambling problems. Discussion and conclusions Young men with gambling problems less frequently prevent the occurrence of stressors and more often react hasty when these occur. While the investigated group reported good social support, this factor was negatively associated with GD only among individuals with good preventive coping. Preventive coping poses a useful construct for selective prevention and treatment as it can be modified in professional interventions.

[Topical problems of social policy with regard to young families].

PubMed

Gerdzhikova, T

1990-01-01

The problem of housing is in the focus of the difficulties of young families. The subjective and objective factors cause inadequate effectiveness of housing legislation for young families. A committee in charge of housing policy has had serious shortcomings in lawmaking. The law spelling out who is entitled to an apartment applied to a 4-member family, however, this definition could also refer to 2 mother with 3 children (sometimes from different biological fathers). Objective factors of the inadequacies include the insufficient number of apartments and the low quality of newly constructed housing. The last accounting of the housing stock of Bulgaria made in December 1985 showed that despite positive results of housing construction the available number of units did not meet the demand. Bulgaria falls short of the number of apartments/1000 population in comparison to developed countries, and this housing stock does not correspond to contemporary standards. There is also a lack of qualified workers in the industry. The material security and welfare of young families is another concern. 82.2% of young families have 1-2 children compared 26.4% of the rest of the families. About 80% of young families receive help from their parents. The general appraisal of the effectiveness of legislation for young households indicates that women under 30 gave birth to the majority of children born. 124,582 live births occurred in 1967; 149,196 births in 1974; and only 122,303 births in 1984. Mothers up to the age of 30 were responsible for 105,757 births in 1967; 132,006 birhs in 1974; and 95,593 births in 1984. Marital fertility increased during 1967-74 among women aged 15-30 as a result of a pronatalist policy in existence during 1967-73, but a reversal was apparent in the following years because of the decline of the living standard of young families.

A parsec-scale optical jet from a massive young star in the Large Magellanic Cloud.

PubMed

McLeod, Anna F; Reiter, Megan; Kuiper, Rolf; Klaassen, Pamela D; Evans, Christopher J

2018-02-15

Highly collimated parsec-scale jets, which are generally linked to the presence of an accretion disk, are commonly observed in low-mass young stellar objects. In the past two decades, a few of these jets have been directly (or indirectly) observed from higher-mass (larger than eight solar masses) young stellar objects, adding to the growing evidence that disk-mediated accretion also occurs in high-mass stars, the formation mechanism of which is still poorly understood. Of the observed jets from massive young stars, none is in the optical regime (massive young stars are typically highly obscured by their natal material), and none is found outside of the Milky Way. Here we report observations of HH 1177, an optical ionized jet that originates from a massive young stellar object located in the Large Magellanic Cloud. The jet is highly collimated over its entire measured length of at least ten parsecs and has a bipolar geometry. The presence of a jet indicates ongoing, disk-mediated accretion and, together with the high degree of collimation, implies that this system is probably formed through a scaled-up version of the formation mechanism of low-mass stars. We conclude that the physics that govern jet launching and collimation is independent of stellar mass.

A parsec-scale optical jet from a massive young star in the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

McLeod, Anna F.; Reiter, Megan; Kuiper, Rolf; Klaassen, Pamela D.; Evans, Christopher J.

2018-02-01

Highly collimated parsec-scale jets, which are generally linked to the presence of an accretion disk, are commonly observed in low-mass young stellar objects. In the past two decades, a few of these jets have been directly (or indirectly) observed from higher-mass (larger than eight solar masses) young stellar objects, adding to the growing evidence that disk-mediated accretion also occurs in high-mass stars, the formation mechanism of which is still poorly understood. Of the observed jets from massive young stars, none is in the optical regime (massive young stars are typically highly obscured by their natal material), and none is found outside of the Milky Way. Here we report observations of HH 1177, an optical ionized jet that originates from a massive young stellar object located in the Large Magellanic Cloud. The jet is highly collimated over its entire measured length of at least ten parsecs and has a bipolar geometry. The presence of a jet indicates ongoing, disk-mediated accretion and, together with the high degree of collimation, implies that this system is probably formed through a scaled-up version of the formation mechanism of low-mass stars. We conclude that the physics that govern jet launching and collimation is independent of stellar mass.

Management of sport-related concussion in young athletes.

PubMed

Patel, Dilip R; Shivdasani, Vandana; Baker, Robert J

2005-01-01

Sport-related head injuries are a common clinical problem. Most head injuries in young athletes are mild traumatic brain injuries or concussions. The highest number of sport-related concussions has been reported in American football. In addition to the well described physical and psychosocial growth, there is ongoing neurocognitive development of the brain during childhood and through adolescence. This developmental process has direct implications in the assessment and management of head injuries in young athletes. Research on the management and long-term outcome following brain injuries in young athletes is limited. Traditionally, the assessment of concussion has been based on clinical history and physical and neurological examination. Increasingly, neuropsychological testing, especially computerised testing, is providing objective measures for the initial assessment and follow-up of young athletes following brain injuries. Numerous guidelines have been published for grading and return to play criteria following concussion; however, none of these have been prospectively validated by research and none are specifically applicable to children and adolescents.

The Effects of Age on Divergent Thinking and Creative Objects Production: A Cross-Sectional Study

ERIC Educational Resources Information Center

Massimiliano, Palmiero

2015-01-01

Age-related changes in divergent thinking and creative objects production were investigated in 150 native Italian speakers, divided into six age groups, each one comprised 25 participants: young (20-29), young adult (30-39), middle aged (40-49), adult-old (50-59), old (60-69), and old-old (70-80). Two tasks were used: the alternative uses task,…

Healthy Behaviors and Lifestyles in Young Adults with a History of Developmental Disabilities

ERIC Educational Resources Information Center

Rurangirwa, Jacqueline; Braun, Kim Van Naarden; Schendel, Diana; Yeargin-Allsopp, Marshalyn

2006-01-01

Objective: Measure select Healthy People 2010 Leading Health Indicators in young adults with and without a history of developmental disabilities (DD) using a population-based cohort. Methods: Young adults were interviewed to assess the prevalence of seven Leading Health Indicators: physical activity, overweight and obesity, tobacco use, substance…

Blinded by the light: on the relationship between CO first overtone emission and mass accretion rate in massive young stellar objects

NASA Astrophysics Data System (ADS)

Ilee, J. D.; Oudmaijer, R. D.; Wheelwright, H. E.; Pomohaci, R.

2018-07-01

To date, there is no explanation as to why disc-tracing CO first overtone (or `bandhead') emission is not a ubiquitous feature in low- to medium-resolution spectra of massive young stellar objects (MYSOs), but instead is only detected towards approximately 25 per cent of their spectra. In this paper, we investigate the hypothesis that only certain mass accretion rates result in detectable bandhead emission in the near-infrared spectra of MYSOs. Using an analytic disc model combined with an LTE model of the CO emission, we find that high accretion rates (≳10-4 M⊙ yr-1) result in large dust sublimation radii, a larger contribution to the K-band continuum from hot dust at the dust sublimation radius, and therefore correspondingly lower CO emission with respect to the continuum. On the other hand, low accretion rates (≲10-6 M⊙ yr-1) result in smaller dust sublimation radii, a correspondingly smaller emitting area of CO, and thus also lower CO emission with respect to the continuum. In general, moderate accretion rates produce the most prominent, and therefore detectable, CO first overtone emission. We compare our findings to a recent near-infrared spectroscopic survey of MYSOs, finding results consistent with our hypothesis. We conclude that the detection rate of CO bandhead emission in the spectra of MYSOs could be the result of MYSOs exhibiting a range of mass accretion rates, perhaps due to the variable accretion suggested by recent multi-epoch observations of these objects.

Blinded by the light: on the relationship between CO first overtone emission and mass accretion rate in massive young stellar objects

NASA Astrophysics Data System (ADS)

Ilee, J. D.; Oudmaijer, R. D.; Wheelwright, H. E.; Pomohaci, R.

2018-04-01

To date, there is no explanation as to why disc-tracing CO first overtone (or `bandhead') emission is not a ubiquitous feature in low- to medium-resolution spectra of massive young stellar objects, but instead is only detected toward approximately 25 per cent of their spectra. In this paper, we investigate the hypothesis that only certain mass accretion rates result in detectable bandhead emission in the near infrared spectra of MYSOs. Using an analytic disc model combined with an LTE model of the CO emission, we find that high accretion rates (≳ 10-4 M⊙yr-1) result in large dust sublimation radii, a larger contribution to the K-band continuum from hot dust at the dust sublimation radius, and therefore correspondingly lower CO emission with respect to the continuum. On the other hand, low accretion rates (≲ 10-6 M⊙yr-1) result in smaller dust sublimation radii, a correspondingly smaller emitting area of CO, and thus also lower CO emission with respect to the continuum. In general, moderate accretion rates produce the most prominent, and therefore detectable, CO first overtone emission. We compare our findings to a recent near-infrared spectroscopic survey of MYSOs, finding results consistent with our hypothesis. We conclude that the detection rate of CO bandhead emission in the spectra of MYSOs could be the result of MYSOs exhibiting a range of mass accretion rates, perhaps due to the variable accretion suggested by recent multi-epoch observations of these objects.

Factors Associated with Young Adults’ Pregnancy Likelihood

PubMed Central

Kitsantas, Panagiota; Lindley, Lisa L.; Wu, Huichuan

2014-01-01

OBJECTIVES While progress has been made to reduce adolescent pregnancies in the United States, rates of unplanned pregnancy among young adults (18–29 years) remain high. In this study, we assessed factors associated with perceived likelihood of pregnancy (likelihood of getting pregnant/getting partner pregnant in the next year) among sexually experienced young adults who were not trying to get pregnant and had ever used contraceptives. METHODS We conducted a secondary analysis of 660 young adults, 18–29 years old in the United States, from the cross-sectional National Survey of Reproductive and Contraceptive Knowledge. Logistic regression and classification tree analyses were conducted to generate profiles of young adults most likely to report anticipating a pregnancy in the next year. RESULTS Nearly one-third (32%) of young adults indicated they believed they had at least some likelihood of becoming pregnant in the next year. Young adults who believed that avoiding pregnancy was not very important were most likely to report pregnancy likelihood (odds ratio [OR], 5.21; 95% CI, 2.80–9.69), as were young adults for whom avoiding a pregnancy was important but not satisfied with their current contraceptive method (OR, 3.93; 95% CI, 1.67–9.24), attended religious services frequently (OR, 3.0; 95% CI, 1.52–5.94), were uninsured (OR, 2.63; 95% CI, 1.31–5.26), and were likely to have unprotected sex in the next three months (OR, 1.77; 95% CI, 1.04–3.01). DISCUSSION These results may help guide future research and the development of pregnancy prevention interventions targeting sexually experienced young adults. PMID:25782849

Hot and cold gas toward young stellar objects

NASA Technical Reports Server (NTRS)

Mitchell, George F.; Maillard, Jean-Pierre; Allen, Mark; Beer, Reinhard; Belcourt, Kenneth

1990-01-01

High-resolution M band spectra are presented for the seven embedded IR sources W3 IRS 5, S140 IRS1, NGC 7538 IRS 1, NGC 7538 IRS 9, GL 2136, LkH-alpha 101, and MWC 349A, and the data are combined with previously published work for W33A and GL 2591. Cold CO is seen toward all nine sources, with temperatures from 11 K to 66 K. Column densities of cold CO are presented. Hot gas is seen toward eight of the nine objects with temperatures from 120 K to 1010 K. New lower limits to the hot gas density are obtained. The hot gas toward GL 2591, GL 2136, W3 IRS 5, and S140 IRS 1 is probably very near the central source and heated via gas-grain collisions. The optical depth in the silicate feature is strongly correlated with the (C-13)O column density, confirming that silicate optical depth is a useful measure of gas column density. The ratio of solid-to-gaseous CO is obtained for seven sources.

Food preparation by young adults is associated with better diet quality.

PubMed

Larson, Nicole I; Perry, Cheryl L; Story, Mary; Neumark-Sztainer, Dianne

2006-12-01

To describe food-preparation behaviors, cooking skills, resources for preparing food, and associations with diet quality among young adults. Cross-sectional analyses were performed in a sample of young adults who responded to the second wave of a population-based longitudinal study. Measures pertaining to food preparation were self-reported and dietary intake was assessed by a food frequency questionnaire, both by a mailed survey. Males (n = 764) and females (n = 946) ages 18 to 23 years. Cross-tabulations and chi2 tests were used to examine associations between food preparation, skills/resources for preparing foods, and characteristics of young adults. Mixed regression models were used to generate expected probabilities of meeting the Healthy People 2010 dietary objectives according to reported behaviors and skills/resources. Food-preparation behaviors were not performed by the majority of young adults even weekly. Sex (male), race (African American), and living situation (campus housing) were significantly related to less frequent food preparation. Lower perceived adequacy of skills and resources for food preparation was related to reported race (African American or Hispanic) and student status (part-time or not in school). The most common barrier to food preparation was lack of time, reported by 36% of young adults. Young adults who reported frequent food preparation reported less frequent fast-food use and were more likely to meet dietary objectives for fat (P < 0.001), calcium (P < 0.001), fruit (P < 0.001), vegetable (P < 0.001), and whole-grain (P = 0.003) consumption. To improve dietary intake, interventions among young adults should teach skills for preparing quick and healthful meals.

A survey for variable young stars with small telescopes: First results from HOYS-CAPS

NASA Astrophysics Data System (ADS)

Froebrich, D.; Campbell-White, J.; Scholz, A.; Eislöffel, J.; Zegmott, T.; Billington, S. J.; Donohoe, J.; Makin, S. V.; Hibbert, R.; Newport, R. J.; Pickard, R.; Quinn, N.; Rodda, T.; Piehler, G.; Shelley, M.; Parkinson, S.; Wiersema, K.; Walton, I.

2018-05-01

Variability in Young Stellar Objects (YSOs) is one of their primary characteristics. Long-term, multi-filter, high-cadence monitoring of large YSO samples is the key to understand the partly unusual light-curves that many of these objects show. Here we introduce and present the first results of the HOYS-CAPScitizen science project which aims to perform such monitoring for nearby (d < 1 kpc) and young (age < 10 Myr) clusters and star forming regions, visible from the northern hemisphere, with small telescopes. We have identified and characterised 466 variable (413 confirmed young) stars in 8 young, nearby clusters. All sources vary by at least 0.2 mag in V, have been observed at least 15 times in V, R and I in the same night over a period of about 2 yrs and have a Stetson index of larger than 1. This is one of the largest samples of variable YSOs observed over such a time-span and cadence in multiple filters. About two thirds of our sample are classical T-Tauri stars, while the rest are objects with depleted or transition disks. Objects characterised as bursters show by far the highest variability. Dippers and objects whose variability is dominated by occultations from normal interstellar dust or dust with larger grains (or opaque material) have smaller amplitudes. We have established a hierarchical clustering algorithm based on the light-curve properties which allows the identification of the YSOs with the most unusual behaviour, and to group sources with similar properties. We discuss in detail the light-curves of the unusual objects V2492 Cyg, V350 Cep and 2MASS J21383981+5708470.

Effects of age on the soccer-specific cognitive-motor performance of elite young soccer players: Comparison between objective measurements and coaches’ evaluation

PubMed Central

Chauvin, Alan; Chassot, Steve; Chenevière, Xavier; Taube, Wolfgang

2017-01-01

The cognitive-motor performance (CMP), defined here as the capacity to rapidly use sensory information and transfer it into efficient motor output, represents a major contributor to performance in almost all sports, including soccer. Here, we used a high-technology system (COGNIFOOT) which combines a visual environment simulator fully synchronized with a motion capture system. This system allowed us to measure objective real-time CMP parameters (passing accuracy/speed and response times) in a large turf-artificial grass playfield. Forty-six (46) young elite soccer players (including 2 female players) aged between 11 and 16 years who belonged to the same youth soccer academy were tested. Each player had to pass the ball as fast and as accurately as possible towards visual targets projected onto a large screen located 5.32 meters in front of him (a short pass situation). We observed a linear age-related increase in the CMP: the passing accuracy, speed and reactiveness of players improved by 4 centimeters, 2.3 km/h and 30 milliseconds per year of age, respectively. These data were converted into 5 point-scales and compared to the judgement of expert coaches, who also used a 5 point-scale to evaluate the same CMP parameters but based on their experience with the players during games and training. The objectively-measured age-related CMP changes were also observed in expert coaches’ judgments although these were more variable across coaches and age categories. This demonstrates that high-technology systems like COGNIFOOT can be used in complement to traditional approaches of talent identification and to objectively monitor the progress of soccer players throughout a cognitive-motor training cycle. PMID:28953958

Effects of age on the soccer-specific cognitive-motor performance of elite young soccer players: Comparison between objective measurements and coaches' evaluation.

PubMed

Hicheur, Halim; Chauvin, Alan; Chassot, Steve; Chenevière, Xavier; Taube, Wolfgang

2017-01-01

The cognitive-motor performance (CMP), defined here as the capacity to rapidly use sensory information and transfer it into efficient motor output, represents a major contributor to performance in almost all sports, including soccer. Here, we used a high-technology system (COGNIFOOT) which combines a visual environment simulator fully synchronized with a motion capture system. This system allowed us to measure objective real-time CMP parameters (passing accuracy/speed and response times) in a large turf-artificial grass playfield. Forty-six (46) young elite soccer players (including 2 female players) aged between 11 and 16 years who belonged to the same youth soccer academy were tested. Each player had to pass the ball as fast and as accurately as possible towards visual targets projected onto a large screen located 5.32 meters in front of him (a short pass situation). We observed a linear age-related increase in the CMP: the passing accuracy, speed and reactiveness of players improved by 4 centimeters, 2.3 km/h and 30 milliseconds per year of age, respectively. These data were converted into 5 point-scales and compared to the judgement of expert coaches, who also used a 5 point-scale to evaluate the same CMP parameters but based on their experience with the players during games and training. The objectively-measured age-related CMP changes were also observed in expert coaches' judgments although these were more variable across coaches and age categories. This demonstrates that high-technology systems like COGNIFOOT can be used in complement to traditional approaches of talent identification and to objectively monitor the progress of soccer players throughout a cognitive-motor training cycle.

Understanding Young Exoplanet Analogs with WISE

NASA Astrophysics Data System (ADS)

Rice, Emily

, the results of our work will improve our understanding of objects at the intersection of stars and planets and be directly applicable to understanding the atmospheres of directly-imaged exoplanets. The assembled investigators are the absolute best team to accomplish this work. They have extensive and diverse observational experience in astrometry, photometry, and spectroscopy from the optical through the mid-IR, spanning nearly the entire spectral energy distribution of young brown dwarfs and encompassing their most fundamental observational properties. They have considerable experience mining large photometric catalogs and identifying low-gravity very low mass objects. The team maintains collaborations with two groups actively modelling brown dwarf and exoplanet atmospheres and interior evolution. The proposed research organically combines several ongoing projects into a cohesive program that will efficiently incorporate WISE data to disentangle the ambiguous and interdependent physical properties of young brown dwarfs. As a result of the team's previous observational projects, we have assembled a dataset that positions us to best interpret WISE observations brown dwarfs and identify new young brown dwarfs in the WISE archive. A significant parallax program is ongoing, and all of the computing resources and many of the analysis tools are already in place, including several well-tested pipelines for data reduction and analysis and model comparisons. The team will incorporate undergraduate students in the project through an existing NSF-funded REU program.

The luminosity function at the end of the main sequence: Results of a deep, large-area, CCD survey for cool dwarfs

NASA Technical Reports Server (NTRS)

Kirkpatrick, J. Davy; Mcgraw, John T.; Hess, Thomas R.; Liebert, James; Mccarthy, Donald W., Jr.

1994-01-01

The luminosity function at the end of the main sequence is determined from V, R, and I data taken by the charge coupled devices (CCD)/Transit Instrument, a dedicated telescope surveying an 8.25 min wide strip of sky centered at delta = +28 deg, thus sampling Galactic latitudes of +90 deg down to -35 deg. A selection of 133 objects chosen via R - I and V - I colors has been observed spectroscopically at the 4.5 m Multiple Mirror Telescope to assess contributions by giants and subdwarfs and to verify that the reddest targets are objects of extremely late spectral class. Eighteen dwarfs of type M6 or later have been discovered, with the latest being of type M8.5. Data used for the determination of the luminosity function cover 27.3 sq. deg down to a completeness limit of R = 19.0. This luminosity function, computed at V, I, and bolometric magnitudes, shows an increase at the lowest luminosities, corresponding to spectral types later than M6- an effect suggested in earlier work by Reid & Gilmore and Legget & Hawkins. When the luminosity function is segregated into north Galactic and south Galactic portions, it is found that the upturn at faint magnitudes exists only in the southern sample. In fact, no dwarfs with M(sub I) is greater than or equal to 12.0 are found within the limiting volume of the 19.4 sq deg northern sample, in stark contrast to the smaller 7.9 sq deg area at southerly latitudes where seven such dwarfs are found. This fact, combined with the fact that the Sun is located approximately 10-40 pc north of the midplane, suggests that the latest dwarfs are part of a young population with a scale height much smaller than the 350 pc value generally adopted for other M dwarfs. These objects comprise a young population either because the lower metallicities prevelant at earlier epochs inhibited the formation of late M dwarfs or because the older counterparts of this population have cooled beyond current detection limits. The latter scenario would hold if these

What do young people think about their school-based sex and relationship education? A qualitative synthesis of young people's views and experiences

PubMed Central

Pound, Pandora; Langford, Rebecca; Campbell, Rona

2016-01-01

Objectives Although sex and relationship education (SRE) represents a key strand in policies to safeguard young people and improve their sexual health, it currently lacks statutory status, government guidance is outdated and a third of UK schools has poor-quality SRE. We aimed to investigate whether current provision meets young people's needs. Design Synthesis of qualitative studies of young people's views of their school-based SRE. Setting Eligible studies originated from the UK, Ireland, the USA, Australia, New Zealand, Canada, Japan, Iran, Brazil and Sweden. Participants Studies of students aged 4–19 in full-time education, young adults ≤19 (not necessarily in full-time education) or adults ≤25 if recalling their experiences of school-based SRE. Results –69 publications were identified, with 55 remaining after quality appraisal (representing 48 studies). The synthesis found that although sex is a potent and potentially embarrassing topic, schools appear reluctant to acknowledge this and attempt to teach SRE in the same way as other subjects. Young people report feeling vulnerable in SRE, with young men anxious to conceal sexual ignorance and young women risking sexual harassment if they participate. Schools appear to have difficulty accepting that some young people are sexually active, leading to SRE that is out of touch with many young people's lives. Young people report that SRE can be negative, gendered and heterosexist. They expressed dislike of their own teachers delivering SRE due to blurred boundaries, lack of anonymity, embarrassment and poor training. Conclusions SRE should be ‘sex-positive’ and delivered by experts who maintain clear boundaries with students. Schools should acknowledge that sex is a special subject with unique challenges, as well as the fact and range of young people's sexual activity, otherwise young people will continue to disengage from SRE and opportunities for safeguarding and improving their sexual health will be

Academic Careers and Post-College Employment of Young Men. Final Report.

ERIC Educational Resources Information Center

Miller, Herman P.; Garfinkle, Stuart

This study of career goals, academic objectives and the relation of these to success in the job market involved a series of annual interviews with samples of people representing four different population groups: young men who were 14 to 24 years old in 1966; men who were 45 to 59 years old in 1966; young women who were 14 to 24 years old in 1968;…

Young Children's Explorations: Young Children's Research?

ERIC Educational Resources Information Center

Murray, Jane

2012-01-01

"Exploration" is recognised as research behaviour; anecdotally, as an early years' teacher, I witnessed many young children exploring. However, young children's self-initiated explorations are rarely regarded as research by adult researchers and policy-makers. The exclusion of young children's autonomous explorations from recognition as…

Assessing the Math Performance of Young ESL Students.

ERIC Educational Resources Information Center

Lee, Fong Yun; Silverman, Fredrick L.; Montoya, Patricia

2002-01-01

Describes proven assessment strategies, which, used separately or in combination, can help young ESL students express their understanding of math concepts while building their English-language skills: Manipulative objects, diagrams, and physical movement. Also describes other assessment techniques including self-assessment, interviewing, and…

Color Vision and Hue Categorization in Young Human Infants

ERIC Educational Resources Information Center

Bornstein, Marc H.; And Others

1976-01-01

The main objective of the present investigations was to determine whether or not young human infants see the physical spectrum in a categorical fashion as human adults and animals who possess color vision regularly do. (Author)

Ape metaphysics: object individuation without language.

PubMed

Mendes, Natacha; Rakoczy, Hannes; Call, Josep

2008-02-01

Developmental research suggests that whereas very young infants individuate objects purely on spatiotemporal grounds, from (at latest) around 1 year of age children are capable of individuating objects according to the kind they belong to and the properties they instantiate. As the latter ability has been found to correlate with language, some have speculated whether it might be essentially language dependent and therefore uniquely human. Existing studies with non-human primates seem to speak against this hypothesis, but fail to present conclusive evidence due to methodological shortcomings. In the present experiments we set out to test non-linguistic object individuation in three great ape species with a refined manual search methodology. Experiment 1 tested for spatiotemporal object individuation: Subjects saw 1 or 2 objects simultaneously being placed inside a box in which they could reach, and then in both conditions only found 1 object. After retrieval of the 1 object, subjects reached again significantly more often when they had seen 2 than when they had seen 1 object. Experiment 2 tested for object individuation according to property/kind information only: Subjects saw 1 object being placed inside the box, and then either found that object (expected) or an object of a different kind (unexpected). Analogously to Experiment 1, after retrieval of the 1 object, subjects reached again significantly more often in the unexpected than in the expected condition. These results thus confirm previous findings suggesting that individuating objects according to their property/kind is neither uniquely human nor essentially language dependent. It remains to be seen, however, whether this kind of object individuation requires sortal concepts as human linguistic thinkers use them, or whether some simpler form of tracking properties is sufficient.

Educational Management within a Young Offender Institution.

ERIC Educational Resources Information Center

Fryer, Winny; Fryer, Paul

1992-01-01

Examines educational theory and objectives within prisons and relates these to the real-time case study of the Young Offender Institution at Whatton, in Nottinghamshire, England. Measuring success and cost effectiveness is extremely difficult in the prison education field, and a significant gap exists between the theoretical model and everyday…

Music for Engaging Young People in Education

ERIC Educational Resources Information Center

Cheong-Clinch, Carmen

2009-01-01

Two music programs were developed specifically to meet therapeutic objectives for newly arrived immigrant and refugee students and for adolescent boys in a residential care facility. The author's observations justify further research to establish whether music can support and nurture the social, physical and mental wellbeing of young people,…

Receptivity to Tobacco Advertising and Promotions Among Young Adolescents as a Predictor of Established Smoking in Young Adulthood

PubMed Central

Gilpin, Elizabeth A.; White, Martha M.; Messer, Karen; Pierce, John P.

2007-01-01

Objectives. We investigated whether receptivity to tobacco advertising and promotions during young adolescence predicts young adult smoking 6 years later. Methods. Two longitudinal cohorts of adolescents drawn from the 1993 and 1996 versions of the California Tobacco Surveys were followed 3 and 6 years later. At baseline, adolescents were aged 12 to 15 years and were not established smokers. The outcome measure was established smoking at final follow-up. Receptivity to cigarette advertising and promotions was included in a multivariate logistic regression analysis along with demographic and other variables. Results. The rate of established smoking at follow-up was significantly greater among members of the 1993 through 1999 cohort (21.0%) than among members of the 1996 through 2002 cohort (15.6%). However, in both cohorts, having a favorite cigarette advertisement and owning or being willing to use a tobacco promotional item showed nearly identical adjusted odds of future adult smoking (1.46 and 1.84, respectively). Conclusions. Despite the success of tobacco control efforts in reducing youth smoking, tobacco marketing remains a potent influence on whether young adolescents become established smokers in young adulthood (18–21 years of age). PMID:17600271

Understanding Tobacco-Related Attitudes among College and Noncollege Young Adult Hookah and Cigarette Users

ERIC Educational Resources Information Center

Lee, Youn Ok; Bahreinifar, Sareh; Ling, Pamela M.

2014-01-01

Objective: To examine differences in tobacco-related attitudes and hookah and cigarette use among college and noncollege young adults. Participants: Time-location samples of young adult bar patrons in San Diego, California ("N" = 2,243), Tulsa ("N" = 2,095) and Oklahoma City ("N" = 2,200), Oklahoma, Albuquerque…

Enabling participation for disabled young people: study protocol.

PubMed

Carroll, Penelope; Witten, Karen; Calder-Dawe, Octavia; Smith, Melody; Kearns, Robin; Asiasiga, Lanuola; Lin, Judy; Kayes, Nicola; Mavoa, Suzanne

2018-06-08

Participation in community life is vital for health and wellbeing, promoting a sense of belonging, networks of social support and opportunities for physical activity. Disabled young people have lower levels of mobility and participation in recreational activities (physical, social and cultural), education and employment, than their peers without disabilities. This has implications for their health and wellbeing and life course opportunities. Previous research on the participation levels of disabled young people has primarily relied on parent/caregiver reports and been oriented to home and school environments. This study investigates how physical and social environmental factors cohere to support or restrict the everyday mobility and participation of disabled young people. The study is located in Auckland, Aotearoa/New Zealand (NZ). Participants comprise 35 young people aged 12-25 years with mobility, vision or hearing impairments. A mixed-methods research design combines objective (global positioning systems, accelerometers, geographical information systems) and self-report measures (travel diaries, and questionnaires) to assess young people's mobility and levels of participation in leisure/educational and employment activities with in-depth interviews exploring their everyday experiences of inclusion/exclusion, and factors enabling or constraining community participation. Parents/caregivers and disability sector key informant viewpoints on the community participation of disabled young people have also been gathered through in-depth interviews. Follow-up workshops with young people and parents/caregivers will identify pathways to increase participation and challenge current disabling practices. This study looks beyond barriers in the physical environment to the interplay of personal, social and physical factors that enable or constrain the community participation of disabled young people. In keeping with the study's overarching goal of increasing opportunities for

Atopy patch tests in young adult patients with atopic dermatitis and controls: dose-response relationship, objective reading, reproducibility and clinical interpretation.

PubMed

Bygum, Anette; Mortz, Charlotte Gotthard; Andersen, Klaus Ejner

2003-01-01

The clinical interpretation and reproducibility of atopy patch tests was studied in 23 selected young adult patients with atopic dermatitis and 25 healthy controls using standard inhalant allergens. Non-invasive measurements were used for objective assessment of test reactions and the participants were retested after 6 weeks. Ten of 19 (53%) evaluable patients with atopic dermatitis had at least one positive atopy patch test. However, there was no clear clinical relevance of the atopy patch test results when related to patient history and distribution of dermatitis. Reproducible and dose-dependent results were obtained with Dermatophagoides pteronyssinus, grass and cat with a reproducibility rate of 0.69 to 0.81 in patients and 0.60-0.96 in controls. A unique finding was a significant positive correlation between a positive atopy patch test, allergen dose and increase in transepidermal water loss and erythema, while measurement of capacitance did not distinguish between positive and negative reactions. The results of the present study do not support the routine use of atopy patch tests in the evaluation of adult patients with atopic dermatitis.

Young Adults' Risk Perceptions of Various Tobacco Products Relative to Cigarettes: Results from the National Young Adult Health Survey

ERIC Educational Resources Information Center

Wackowski, Olivia A.; Delnevo, Cristine D.

2016-01-01

Objectives: Tobacco product risk perceptions may influence whether individuals use those products instead of or in addition to regular cigarettes. This study aimed to explore risk perceptions of various tobacco products relative to traditional cigarettes with young adults, a group with higher rates of tobacco use. Method: We examined risk…

Measurement of Young's modulus in the in vivo human vocal folds.

PubMed

Tran, Q T; Berke, G S; Gerratt, B R; Kreiman, J

1993-08-01

Currently, surgeons have no objective means to evaluate and optimize results of phonosurgery intraoperatively. Instead, they usually judge the vocal folds subjectively by visual inspection or by listening to the voice. This paper describes a new device that measures Young's (elastic) modulus values for the human vocal fold intraoperatively. Physiologically, the modulus of the vocal fold may be important in determining the nature of vocal fold vibration in normal and pathologic states. This study also reports the effect of recurrent laryngeal nerve stimulation on Young's modulus of the human vocal folds, measured by means of transcutaneous nerve stimulation techniques. Young's modulus increased with increases in current stimulation to the recurrent laryngeal nerve. Ultimately, Young's modulus values may assist surgeons in optimizing the results of various phonosurgeries.

Cannabis and Anxiety and Depression in Young Adults: A Large Prospective Study

ERIC Educational Resources Information Center

Hayatbakhsh, Mohammad R.; Najman, Jake M.; Jamrozik, Konrad; Mamun, Abdullah A.; Alati, Rosa; Bor, William

2007-01-01

Objective: To examine whether age of first use or frequency of use of cannabis is associated with anxiety and depression (AD) in young adults, independent of known potential confounders, including the use of other illicit drugs. Method: A cohort of 3,239 Australian young adults was followed from birth to the age of 21 when data on AD were obtained…

Twin Study on Heritability of Activity, Attention, and Impulsivity as Assessed by Objective Measures

ERIC Educational Resources Information Center

Heiser, Philip; Heinzel-Gutenbrunner, Monika; Frey, Joachim; Smidt, Judith; Grabarkiewicz, Justyna; Friedel, Susann; Kuhnau, Wolfgang; Schmidtke, Jorg; Remschmidt, Helmut; Hebebrand, Johannes

2006-01-01

Objective: The purpose of this study was to assess heritability of activity, attention, and impulsivity by comparing young monozygotic (MZ) twins with dizygotic (DZ) twins using objective measures. Method: The OPTAx test is an infrared motion analysis to record the movement pattern during a continuous performance test. Seventeen MZ and 12 same…

Evaluating growth performance of young stands

Treesearch

A. L. Roe; R. E. Benson

1966-01-01

A simple procedure for evaluating the diameter growth of young stands in relation to potential growth is described. A comparison technique is developed which contrasts relative diameter of crop trees to the relative diameter growth of the last decade to show the condition and trend of growth in the stand. The method is objective, easy to use, and has several...

Extreme star formation in the Milky Way: luminosity distributions of young stellar objects in W49A and W51

NASA Astrophysics Data System (ADS)

Eden, D. J.; Moore, T. J. T.; Urquhart, J. S.; Elia, D.; Plume, R.; König, C.; Baldeschi, A.; Schisano, E.; Rigby, A. J.; Morgan, L. K.; Thompson, M. A.

2018-07-01

We have compared the star-formation properties of the W49A and W51 regions by using far-infrared data from the Herschel infrared Galactic Plane Survey (Hi-GAL) and 850-μm observations from the James Clerk Maxwell Telescope (JCMT) to obtain luminosities and masses, respectively, of associated compact sources. The former are infrared luminosities from the catalogue of Elia et al., while the latter are from the JCMT Plane survey source catalogue as well as measurements from new data. The clump-mass distributions of the two regions are found to be consistent with each other, as are the clump-formation efficiency and star-formation efficiency analogues. However, the frequency distributions of the luminosities of the young stellar objects are significantly different. While the luminosity distribution in W51 is consistent with Galaxy-wide samples, that of W49A is top heavy. The differences are not dramatic and are concentrated in the central regions of W49A. However, they suggest that physical conditions there, which are comparable in part to those in extragalactic starbursts, are significantly affecting the star-formation properties or evolution of the dense clumps in the region.

Extreme star formation in the Milky Way: Luminosity distributions of young stellar objects in W49A and W51

NASA Astrophysics Data System (ADS)

Eden, D. J.; Moore, T. J. T.; Urquhart, J. S.; Elia, D.; Plume, R.; König, C.; Baldeschi, A.; Schisano, E.; Rigby, A. J.; Morgan, L. K.; Thompson, M. A.

2018-03-01

We have compared the star-formation properties of the W49A and W51 regions by using far-infrared data from the Herschel infrared Galactic Plane Survey (Hi-GAL) and 850-μm observations from the James Clerk Maxwell Telescope (JCMT) to obtain luminosities and masses, respectively, of associated compact sources. The former are infrared luminosities from the catalogue of Elia et al. (2017), while the latter are from the JCMT Plane survey source catalogue as well as measurements from new data. The clump-mass distributions of the two regions are found to be consistent with each other, as are the clump-formation efficiency and star-formation efficiency analogues. However, the frequency distributions of the luminosities of the young stellar objects are significantly different. While the luminosity distribution in W51 is consistent with Galaxy-wide samples, that of W49A is top-heavy. The differences are not dramatic, and are concentrated in the central regions of W49A. However, they suggest that physical conditions there, which are comparable in part to those in extragalactic starbursts, are significantly affecting the star-formation properties or evolution of the dense clumps in the region.

Changing the Culture of Young People's Binge Drinking: From Motivations to Practical Solutions

ERIC Educational Resources Information Center

Coleman, Lester; Cater, Suzanne

2007-01-01

Aims: This paper explores young people's own opinions about how the "drinking to get drunk" culture can be changed. More precisely, the two objectives of this study were to explore: (1) whether young people viewed binge drinking as a real "problem"; and (2) what they thought could be done to reduce binge drinking. Methods:…

Young Investigator Research Program (YIP)

NASA Astrophysics Data System (ADS)

Robinson, Ellen

The Air Force YIP supports scientists and engineers who have received Ph.D. or equivalent degrees in the last five years and show exceptional ability and promise for conducting basic research. The objective of this program is to foster creative basic research in science and engineering; enhance early career development of outstanding young investigators; and increase opportunities for the young investigator to recognize the Air Force mission and related challenges in science and engineering. Individual awards will be made to U.S. institutions of higher education, industrial laboratories or non-profit research organizations where the principal investigator is a U.S. citizen, national or permanent resident; employed on a full-time basis and hold a regular position. Researchers working at the Federally Funded Research and Development Centers and DoD Laboratories will not be considered for the YIP competition. Each award will be funded at the 120K level for three years. Exceptional proposals will be considered individually for higher funding levels and longer duration. http://www.wpafb.af.mil/Welcome/Fact-Sheets/Display/Article/842100#anchor2 I will brief Air Force Office Of Scientific Research Young Investigator Research Program.

Earlier and greater hand pre-shaping in the elderly: a study based on kinematic analysis of reaching movements to grasp objects.

PubMed

Tamaru, Yoshiki; Naito, Yasuo; Nishikawa, Takashi

2017-11-01

Elderly people are less able to manipulate objects skilfully than young adults. Although previous studies have examined age-related deterioration of hand movements with a focus on the phase after grasping objects, the changes in the reaching phase have not been studied thus far. We aimed to examine whether changes in hand shape patterns during the reaching phase of grasping movements differ between young adults and the elderly. Ten healthy elderly adults and 10 healthy young adults were examined using the Simple Test for Evaluating Hand Functions and kinetic analysis of hand pre-shaping reach-to-grasp tasks. The results were then compared between the two groups. For kinetic analysis, we measured the time of peak tangential velocity of the wrist and the inter-fingertip distance (the distance between the tips of the thumb and index finger) at different time points. The results showed that the elderly group's performance on the Simple Test for Evaluating Hand Functions was significantly lower than that of the young adult group, irrespective of whether the dominant or non-dominant hand was used, indicating deterioration of hand movement in the elderly. The peak tangential velocity of the wrist in either hand appeared significantly earlier in the elderly group than in the young adult group. The elderly group also showed larger inter-fingertip distances with arch-like fingertip trajectories compared to the young adult group for all object sizes. To perform accurate prehension, elderly people have an earlier peak tangential velocity point than young adults. This allows for a longer adjustment time for reaching and grasping movements and for reducing errors in object prehension by opening the hand and fingers wider. Elderly individuals gradually modify their strategy based on previous successes and failures during daily living to compensate for their decline in dexterity and operational capabilities. © 2017 Japanese Psychogeriatric Society.

Accuracy of self-reported sleep parameters compared with actigraphy in young people with mental ill-health.

PubMed

Biddle, Daniel J; Robillard, Rébecca; Hermens, Daniel F; Hickie, Ian B; Glozier, Nicholas

2015-09-01

Validation of self-report assessment of habitual sleep duration and onset time in young people with mental ill-health. Validation sample. Specialized early intervention centers for young people in Sydney, Australia. One hundred and forty-six young people with mental ill-health. N/A. Self-reported habitual sleep duration and onset time were compared against at least 7 days of actigraphy monitoring. Average bias in and calibration of subjective measures were assessed, along with correlation of subjective and objective measures. Differences by age, sex, mental-disorder type, and reported insomnia were also explored. On average, subjective estimates of sleep were unbiased. Overall, each additional hour of objective habitual sleep duration predicted 41 minutes more subjective habitual sleep duration, and each hour later objective habitual sleep onset occurred predicted a 43-minute later subjective habitual sleep onset. There were subgroup differences: subjective habitual sleep duration in self-reported insomnia was shorter than objective duration by 30 minutes (SD = 119), on average. Calibration of habitual sleep duration was worse for those with mood disorders than with other primary diagnoses (t = -2.39, P = .018). Correlation between subjective and objective measures was strong for sleep onset time (Á = .667, P < .001) and moderate for sleep duration (r = .332, P < .001). For the mood disorder group, subjective and objective sleep durations were uncorrelated. Self-reports seem valid for large-scale studies of habitual sleep duration and onset in help-seeking young people, but assessment of habitual sleep duration requires objective measures where individual accuracy is important. Copyright © 2015 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.

Peer Communication in Online Mental Health Forums for Young People: Directional and Nondirectional Support

PubMed Central

Hanley, Terry; Ujhelyi, Katalin

2017-01-01

Background The Internet has the potential to help young people by reducing the stigma associated with mental health and enabling young people to access services and professionals which they may not otherwise access. Online support can empower young people, help them develop new online friendships, share personal experiences, communicate with others who understand, provide information and emotional support, and most importantly help them feel less alone and normalize their experiences in the world. Objective The aim of the research was to gain an understanding of how young people use an online forum for emotional and mental health issues. Specifically, the project examined what young people discuss and how they seek support on the forum (objective 1). Furthermore, it looked at how the young service users responded to posts to gain an understanding of how young people provided each other with peer-to-peer support (objective 2). Methods Kooth is an online counseling service for young people aged 11-25 years and experiencing emotional and mental health problems. It is based in the United Kingdom and provides support that is anonymous, confidential, and free at the point of delivery. Kooth provided the researchers with all the online forum posts between a 2-year period, which resulted in a dataset of 622 initial posts and 3657 initial posts with responses. Thematic analysis was employed to elicit key themes from the dataset. Results The findings support the literature that online forums provide young people with both informational and emotional support around a wide array of topics. The findings from this large dataset also reveal that this informational or emotional support can be viewed as directive or nondirective. The nondirective approach refers to when young people provide others with support by sharing their own experiences. These posts do not include explicit advice to act in a particular way, but the sharing process is hoped to be of use to the poster. The

Isolated and companion young brown dwarfs in the taurus and chamaeleon molecular clouds

PubMed

Tamura; Itoh; Oasa; Nakajima

1998-11-06

Infrared imaging observations have detected a dozen faint young stellar objects (YSOs) in the Taurus and Chamaeleon molecular clouds whose near-infrared colors are similar to those of classical T Tauri stars (TTS). They are around four magnitudes fainter than low-luminosity YSOs in Taurus detected in earlier surveys and as much as eight magnitudes fainter than typical TTS. The extreme faintness of the objects and their lower luminosity relative to previously identified brown dwarfs in the Pleiades indicate that these faint YSOs are very young brown dwarfs on the order of 1 million years old.

Upper limb motor function in young adults with spina bifida and hydrocephalus

PubMed Central

Salman, M. S.; Jewell, D.; Hetherington, R.; Spiegler, B. J.; MacGregor, D. L.; Drake, J. M.; Humphreys, R. P.; Gentili, F.

2011-01-01

Objective The objective of the study was to measure upper limb motor function in young adults with spina bifida meningomyelocele (SBM) and typically developing age peers. Method Participants were 26 young adults with SBM, with a Verbal or Performance IQ score of at least 70 on the Wechsler scales, and 27 age- and gender-matched controls. Four upper limb motor function tasks were performed under four different visual and cognitive challenge conditions. Motor independence was assessed by questionnaire. Results Fewer SBM than control participants obtained perfect posture and rebound scores. The SBM group performed less accurately and was more disrupted by cognitive challenge than controls on limb dysmetria tasks. The SBM group was slower than controls on the diadochokinesis task. Adaptive motor independence was related to one upper limb motor task, arm posture, and upper rather than lower spinal lesions were associated with less motor independence. Conclusions Young adults with SBM have significant limitations in upper limb function and are more disrupted by some challenges while performing upper limb motor tasks. Within the group of young adults with SBM, upper spinal lesions compromise motor independence more than lower spinal lesions. PMID:19672605

Acute coronary syndrome in young adults from a Malaysian tertiary care centre

PubMed Central

Hoo, Fan Kee; Foo, Yoke Loong; Lim, Sazlyna Mohd Sazlly; Ching, Siew Mooi; Boo, Yang Liang

2016-01-01

Background and Objective: Acute coronary syndrome (ACS) is one of the leading cause of morbidity and mortality worldwide. It is relatively uncommon in young adults as compared to the older population. Our objective was to assess the prevalence, demographic distribution, and risk factors for acute coronary syndrome (ACS) in patients less than 45 years of age admitted to a Malaysian tertiary care centre. Methods: This is a cross-sectional, retrospective, and single centre study with random sampling of the patients admitted for ACS to hospital from January 2005 to December 2013. Data were collected and analyzed. Patients less than 45 years of age were compared with patients more than 45 years of age. Result: A total of 628 patients were included in the study and with the prevalence of young ACS was 6.1% and mean age of 39±6 years. All the young ACS patients were diagnosed with unstable angina and non-ST elevation myocardial infarction (NSTEMI). Tobacco smoking and family history of coronary artery disease (CAD) were more frequent in young ACS. 59.5% of the young ACS patients were smokers, while 37.8% and 51.4% of them were found to suffer from diabetes mellitus and hypertension respectively. Tobacco smoking, diabetes mellitus, and hypertension had shown significant association with the onset of young ACS (p ≤ 0.05). Conclusion: Three leading risk factors (tobacco smoking, diabetes mellitus, and hypertension) had been shown to be significantly associated with the onset of young ACS. Thus, it is important to identify this cohort and implement aggressive measures in tackling the risk factors in order to prevent or halt the development of coronary artery disease. PMID:27648025

Objective evaluation of the changes in the crystalline lens during accommodation in young and presbyopic populations using Pentacam HR system.

PubMed

Ni, Yao; Liu, Xia-Lin; Wu, Ming-Xing; Lin, Ying; Sun, Yu-Ying; He, Chang; Liu, Yi-Zhi

2011-01-01

To quantify the changes in the lens profile with accommodation in different age groups. The Pentacam HR system was used to obtain the images of the anterior eye segment from 23 young and 15 presbyopic emmetropic subjects in unaccommodated (with an accommodation stimulus of 0.0D) and accommodated (with an accommodation stimulus of 5.0D for the young group and 1.0D for the presbyopic group) states. The phakic crystalline lens shape, including curvature of crystalline lens and central lens thickness (CLT), and the measurements of anterior segment length (ASL), central anterior chamber depth (CACD) were investigated. The anterior chamber volume (ACV) was also measured. The reduction of CACD and ACV were significant in both groups after accommodation stimulus. From the profile of anterior eye segment, a significant decrease in anterior crystalline lens radii of curvature (-2.52mm) and a mean increase in CLT (0.222mm) and ASL (0.108mm) were found in the young group with an accommodation stimulus of 5.0D. However, no statistically significant changes of CLT, ASL, or crystalline lens radii of curvature were found in the presbyopic group. Our data showed that the shallowing of anterior chamber during accommodation was caused by the forward bulging of the anterior lens surface, rather than by anterior shifting of lens position in either young or presbyopic subjects.

The Religious Behavior and Beliefs of Orthodox Young People in the Mogilev Area

ERIC Educational Resources Information Center

Iudin, V. V.

2007-01-01

In the past twenty years a generation has grown up that, unlike previous generations, was not the object of atheistic upbringing. In this article, based on sociological surveys of young people in Mogilev and Mogilev Oblast conducted in 2002 and 2004, the author examines the religious behavior of young believers and analyze the level and degree of…

Behavioral Profiles Associated with Objective Sleep Duration in Young Children with Insomnia Symptoms.

PubMed

Calhoun, Susan L; Fernandez-Mendoza, Julio; Vgontzas, Alexandros N; Mayes, Susan D; Liao, Duanping; Bixler, Edward O

2017-02-01

Based on previous studies reporting on the association of objective sleep duration and physiologic changes (i.e., increased cortisol) in children, we examined the role of objective sleep duration on differentiating behavioral profiles in children with insomnia symptoms. Seven hundred children (ages 5-12, 47.8% male) from the Penn State Child Cohort underwent a nine-hour polysomnography and parent completed Pediatric Behavior Scale. Insomnia symptoms were defined as parent report of difficulty falling and/or staying asleep, sleep disordered breathing as an AHI of ≥1, and objective short sleep duration as a total sleep time < 7.7 h. Children with insomnia symptoms demonstrated more overall behavioral problems than controls. Significant interactions between insomnia symptoms and objective sleep duration on scores of externalizing behaviors, mood variability and school problems were found. Profile analyses showed that children with insomnia symptoms and normal sleep duration were associated with clinically elevated externalizing behaviors, inattention, mood variability, and school problems, while children with insomnia and short sleep duration were associated with an overall elevated profile in which internalizing behaviors were more prominent. Childhood insomnia symptoms are associated with a wide array of behavioral problems, for which objective sleep duration is useful in differentiating behavioral profiles. Children with insomnia symptoms and normal sleep duration had a behavioral profile consistent with limit-setting and rule-breaking behaviors, while children with insomnia symptoms and short sleep duration had a behavioral profile more consistent with internalizing behaviors resembling that of psychophysiological disorders.

Childhood Predictors of Young Adult Social Functioning in 22q11.2 Deletion Syndrome

ERIC Educational Resources Information Center

Wagner, Kayla E.; Kates, Wendy R.; Fremont, Wanda; Antshel, Kevin M.

2017-01-01

The primary objectives of the current prospective longitudinal study were to (a) describe social functioning outcomes and (b) identify childhood predictors of social functioning in young adults with (22q11.2DS). Childhood predictors of young adult social functioning were examined. Family environment and parental stress in adolescence were…

Does everything happen when you are young? Introducing the youth bias.

PubMed

Koppel, Jonathan; Berntsen, Dorthe

2014-01-01

The reminiscence bump refers to the disproportionate number of individuals' autobiographical memories that date from young adulthood. A similar bump is found in cultural life scripts: When people are asked to nominate and date major transitional events in a typical life course in their culture, a disproportionate number of the events cited are likewise expected to occur in young adulthood. Across two online studies, we tested whether these effects reflect a broader tendency to ascribe most important events to young adulthood. Specifically, we probed, in adult USA samples, for when individuals expect the most important public event of a typical person's life to take place. Although the occurrence of such public events should be randomly distributed across the lifespan, we found a bump in young adulthood. We found this bump in both subjective (Study 1; probing cultural expectations for the expected timing of the public event that a typical person considers to be the most important of their lifetime) and objective (Study 2; probing cultural expectations for the expected timing of the objectively most important public event of a typical person's lifetime) conditions. We term this set of cultural expectations the youth bias and discuss its implications for human cognition.

Objective reports versus subjective perceptions of crime and their relationships to accelerometer-measured physical activity in Hispanic caretaker-child dyads

PubMed Central

van Bakergem, Margaret; Sommer, Evan C.; Heerman, William J.; Hipp, James Aaron; Barkin, Shari L.

2016-01-01

Crime and safety are commonly cited barriers to physical activity (PA). We had three objectives, 1) describe the association between objective crime measures and perceptions of crime, 2) analyze the relationships between each type of crime and accelerometer-measured physical activity in caretakers and young children (ages 3–5 years), and 3) explore for early gender differences in the relationship between crime and physical activity in young children. Data are from the cross-sectional baseline data of an ongoing randomized controlled trial in Nashville, Tennessee spanning September 2012 through May 2014. Data was analyzed from 480 Hispanic dyads (adult caretaker and 3–5 year old child). Objective crime rate was assessed in ArcGIS and perception of crime was measured by caretaker agreement with the statement “The crime rate in my neighborhood makes it unsafe to go on walks.” The primary outcome was accelerometer-measured physical activity over seven consecutive days. Objective and perceived crime were significantly positively correlated. Caretaker vigorous PA was significantly related to perceptions of crime; however, its relationship to objective crime was not significant. Child PA was not significantly related to caretaker perceptions of crime. However, interactions suggested that the relationship between crime rate and PA was significantly more negative for girls than for boys. Objective and subjective measures of crime rate are expected to be important correlates of PA, but they appear to have complex relationships that are different for adults than they are for young children, as well as for young girls compared to boys, and research has produced conflicting findings. PMID:27939263

A New Functional Health Literacy Scale for Japanese Young Adults Based on Item Response Theory.

PubMed

Tsubakita, Takashi; Kawazoe, Nobuo; Kasano, Eri

2017-03-01

Health literacy predicts health outcomes. Despite concerns surrounding the health of Japanese young adults, to date there has been no objective assessment of health literacy in this population. This study aimed to develop a Functional Health Literacy Scale for Young Adults (funHLS-YA) based on item response theory. Each item in the scale requires participants to choose the most relevant term from 3 choices in relation to a target item, thus assessing objective rather than perceived health literacy. The 20-item scale was administered to 1816 university students and 1751 responded. Cronbach's α coefficient was .73. Difficulty and discrimination parameters of each item were estimated, resulting in the exclusion of 1 item. Some items showed different difficulty parameters for male and female participants, reflecting that some aspects of health literacy may differ by gender. The current 19-item version of funHLS-YA can reliably assess the objective health literacy of Japanese young adults.

Exploring the Influence of a Smartphone App (Young with Diabetes) on Young People’s Self-Management: Qualitative Study

PubMed Central

Husted, Gitte Reventlov; Weis, Janne; Teilmann, Grete

2018-01-01

Background Adequate self-management is the cornerstone of preventing type 1 diabetes mellitus (T1DM) complications. However, T1DM self-management is challenging for young people, who often struggle during the transition from childhood to adulthood. The mobile health (mHealth) app Young with Diabetes (YWD) was developed in collaboration with young people to enhance their T1DM self-management during this transition. Objective The purpose of this study was to explore the influence of YWD on young people’s self-management during a 12-month period. Methods A qualitative explorative approach was used, comprising a purposive sample of 20 young people (11 females and 9 males, ages 15 to 23 years, with app use of 3 to 64 days) from 3 pediatric and 3 adult departments. Participants were interviewed individually using a semistructured interview guide. Data were collected from January to March 2017 and analyzed using thematic analysis. Results A total of 5 themes were identified: (1) not feeling alone anymore (“we are in this together”); (2) gaining competence by sharing experiences and practical knowledge (“they know what they are talking about”); (3) feeling safer (“it’s just a click away”); (4) breaking the ice by starting to share thoughts and feelings and asking for help (“it is an outstretched hand”); and (5) lack of motivating factors (“done with the app”). Young people reported that YWD promoted self-management by peer-to-peer social support, exchanging messages with health care providers, and sharing YWD with parents. Participants recommended YWD as a supplement to self-management for newly diagnosed young people with T1DM and suggested improvements in app content and functionality. Conclusions The mHealth app YWD has the potential to support self-management. In particular, peer-to-peer support reduced feelings of loneliness and helped young people to gain knowledge and skills for managing T1DM. A need exists for alternative ways to train

Alcohol industry and governmental revenue from young Australians.

PubMed

Li, Ian W; Si, Jiawei

2016-11-01

Objective The aim of the present study was to estimate the revenues collected by government and industry from alcohol consumption by young Australians in 2010. Methods Statistical analyses were performed on data from the Australian National Drug Strategy Household Survey 2010 and alcohol data collected from an online retailer to calculate the proportion, frequency, quantity and revenues from alcohol consumption by young Australians. Results One-third of adolescents (12-17 years old) and 85% of young adults (18-25 years old) consume alcohol. More than half the adolescents' alcohol consumption is from ready-to-drink spirits. Revenue generated from alcohol consumption by 12-25 year olds is estimated at $4.8 billion in 2010 (2014 Australian dollars): $2.8 billion to industry (sales) and $2.0 billion to government (taxes). Conclusions Alcohol consumption by young Australians is prevalent, and young Australian drinkers consume alcohol in substantial amounts. The industry and taxation revenue from young drinkers is also considerable. It would be in the public interest to divert some of this revenue towards health initiatives to reduce drinking by young people, especially given the high societal costs of alcohol consumption. What is known about the topic? Australian adolescents aged 12-17 years consume substantial amounts of alcohol, and substantial amounts of revenue are generated from alcohol sales to them. What does this paper add? This paper provides recent estimates of alcohol consumption and revenue generated by Australian adolescents, and extends estimates to young adults aged 18-25 years. What are the implications for practitioners? A substantial proportion of Australian young people consume alcohol. The sales and taxation revenue generated from young people's drinking is substantial at A$4.8 billion in 2010 and is higher in real terms than estimates from previous studies. Some of the alcohol taxation revenue could be diverted to health promotion and education for

Primeval very low-mass stars and brown dwarfs - III. The halo transitional brown dwarfs

NASA Astrophysics Data System (ADS)

Zhang, Z. H.; Pinfield, D. J.; Gálvez-Ortiz, M. C.; Homeier, D.; Burgasser, A. J.; Lodieu, N.; Martín, E. L.; Osorio, M. R. Zapatero; Allard, F.; Jones, H. R. A.; Smart, R. L.; Martí, B. López; Burningham, B.; Rebolo, R.

2018-05-01

We report the discovery of an esdL3 subdwarf, ULAS J020858.62+020657.0 and a usdL4.5 subdwarf, ULAS J230711.01+014447.1. They were identified as L subdwarfs by optical spectra obtained with the Gran Telescopio Canarias, and followed up by optical to near infrared spectroscopy with the Very Large Telescope. We also obtained an optical to near infrared spectrum of a previously known L subdwarf, ULAS J135058.85+081506.8, and re-classified it as a usdL3 subdwarf. These three objects all have typical halo kinematics. They have Teff around 2050-2250 K, -1.8 ≤ [Fe/H] ≤-1.5, and mass around 0.0822-0.0833 M⊙, according to model spectral fitting and evolutionary models. These sources are likely halo transitional brown dwarfs with unsteady hydrogen fusions, as their masses are just below the hydrogen-burning minimum mass, which is ˜ 0.0845 M⊙ at [Fe/H] = -1.6 and ˜ 0.0855 M⊙ at [Fe/H] = -1.8. Including these, there are now nine objects in the `halo brown dwarf transition zone', which is a `substellar subdwarf gap' spans a wide temperature range within a narrow mass range of the substellar population.

A SUBTLE INFRARED EXCESS ASSOCIATED WITH A YOUNG WHITE DWARF IN THE EDINBURGH-CAPE BLUE OBJECT SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dennihy, E.; Dunlap, B. H.; Clemens, J. C.

We report the discovery of a subtle infrared excess associated with the young white dwarf EC 05365–4749 at 3.35 and 4.6 μ m. Follow-up spectroscopic observations are consistent with a hydrogen atmosphere white dwarf of effective temperature 22,800 K and log [ g (cm s{sup −2})] = 8.19. High-resolution spectroscopy reveals atmospheric metal pollution with logarithmic abundances of [Mg/H] = −5.36 and [Ca/H] = −5.75, confirming the white dwarf is actively accreting from a metal-rich source with an intriguing abundance pattern. We find that the infrared excess is well modeled by a flat, opaque debris disk, though disk parameters aremore » not well constrained by the small number of infrared excess points. We further demonstrate that relaxing the assumption of a circular dusty debris disk to include elliptical disks expands the widths of acceptable disks, adding an alternative interpretation to the subtle infrared excesses commonly observed around young white dwarfs.« less

Examining the Conflict and Interconnectedness of Young People's Ideas about Environmental Issues, Responsibility and Action

ERIC Educational Resources Information Center

Wilks, Leigh; Harris, Neil

2016-01-01

Objective: Young people's environmental views are typically conflicted, with little recognition of the links between environmental issues or between environmental responsibility and action. The purpose of this study was to clarify whether young people's understanding of the environment is in conflict or whether they are forming interconnections…

The Human First Hypothesis: Identification of Conspecifics and Individuation of Objects in the Young Infant

ERIC Educational Resources Information Center

Bonatti, Luca; Frot, Emmanuel; Zangl, Renate; Mehler, Jacques

2002-01-01

How do infants individuate and track objects, and among them objects belonging to their species, when they can only rely on information about the properties of those objects? We propose the Human First Hypothesis (HFH), which posits that infants possess information about their conspecifics and use it to identify and count objects. F. Xu and S.…

International Deep Planet Survey, 317 stars to determine the wide-separated planet frequency

NASA Astrophysics Data System (ADS)

Galicher, R.; Marois, C.; Macintosh, B.; Zuckerman, B.; Song, I.; Barman, T.; Patience, J.

2013-09-01

Since 2000, more than 300 nearby young stars were observed for the International Deep Planet Survey with adaptive optics systems at Gemini (NIRI/NICI), Keck (Nirc2), and VLT (Naco). Massive young AF stars were included in our sample whereas they have generally been neglected in first generation surveys because the contrast and target distances are less favorable to image substellar companions. The most significant discovery of the campaign is the now well-known HR 8799 multi-planet system. This remarkable finding allows, for the first time, an estimate of the Jovians planet population at large separations (further than a few AUs) instead of deriving upper limits. During my presentation, I will present the survey showing images of multiple stars and planets. I will then propose a statistic study of the observed stars deriving constraints on the Jupiter-like planet frequency at large separations.

Combining angular differential imaging and accurate polarimetry with SPHERE/IRDIS to characterize young giant exoplanets

NASA Astrophysics Data System (ADS)

van Holstein, Rob G.; Snik, Frans; Girard, Julien H.; de Boer, Jozua; Ginski, C.; Keller, Christoph U.; Stam, Daphne M.; Beuzit, Jean-Luc; Mouillet, David; Kasper, Markus; Langlois, Maud; Zurlo, Alice; de Kok, Remco J.; Vigan, Arthur

2017-09-01

Young giant exoplanets emit infrared radiation that can be linearly polarized up to several percent. This linear polarization can trace: 1) the presence of atmospheric cloud and haze layers, 2) spatial structure, e.g. cloud bands and rotational flattening, 3) the spin axis orientation and 4) particle sizes and cloud top pressure. We introduce a novel high-contrast imaging scheme that combines angular differential imaging (ADI) and accurate near-infrared polarimetry to characterize self-luminous giant exoplanets. We implemented this technique at VLT/SPHEREIRDIS and developed the corresponding observing strategies, the polarization calibration and the data-reduction approaches. The combination of ADI and polarimetry is challenging, because the field rotation required for ADI negatively affects the polarimetric performance. By combining ADI and polarimetry we can characterize planets that can be directly imaged with a very high signal-to-noise ratio. We use the IRDIS pupil-tracking mode and combine ADI and principal component analysis to reduce speckle noise. We take advantage of IRDIS' dual-beam polarimetric mode to eliminate differential effects that severely limit the polarimetric sensitivity (flat-fielding errors, differential aberrations and seeing), and thus further suppress speckle noise. To correct for instrumental polarization effects, we apply a detailed Mueller matrix model that describes the telescope and instrument and that has an absolute polarimetric accuracy <= 0.1%. Using this technique we have observed the planets of HR 8799 and the (sub-stellar) companion PZ Tel B. Unfortunately, we do not detect a polarization signal in a first analysis. We estimate preliminary 1σ upper limits on the degree of linear polarization of ˜ 1% and ˜ 0.1% for the planets of HR 8799 and PZ Tel B, respectively. The achieved sub-percent sensitivity and accuracy show that our technique has great promise for characterizing exoplanets through direct-imaging polarimetry

New Herbig-Haro objects in star-forming regions

NASA Technical Reports Server (NTRS)

Reipurth, BO; Graham, J. A.

1988-01-01

A list of 25 new Herbig-Haro objects, HH 58 to HH 82, in the Orion molecular clouds and in southern molecular cloud complexes has been compiled. CCD images in the S II 6717, 6731 forbidden lines are presented for the objects, together with a few spectra and some IR observations. The individual objects and, when identified, their energy sources are discussed. HH 65 is located in the red lobe of the bipolar outflow associated with the highly variable reflection nebula Re 50. HH 67 is a 22-arcsec long sinusoidal jet. HH 68/69 consists of a long, linear chain of four HH knots. HH 72 emerges from a 120-solar luminosity IRAS source embedded in a Bok globule. HH 79 is the first HH object discovered in the Ophiuchus clouds. HH 80/81 in Sagittarius are among the brightest HH objects known, have complex velocities, high excitation conditions and emerge from a 6000-solar luminosity young B-star. HH 82 is associated with the bright variable star S Coronae Australis.

Is This Speck of Light an Exoplanet?

NASA Astrophysics Data System (ADS)

2004-09-01

nature of this intriguing object. Thus, the astronomers refer to it as a "Giant Planet Candidate Companion (GPCC)" [4]. Observations will now be made to ascertain whether the motion in the sky of GPCC is compatible with that of a planet orbiting 2M1207. This should become evident within 1-2 years at the most. PR Photo 26a/04: NACO image of the brown dwarf object 2M1207 and GPCC PR Photo 26b/04: Near-infrared spectrum of the brown dwarf object 2M1207 and GPCC PR Photo 26c/04: Comparison between the possible 2M1207 system and the solar system Just a speck of light ESO PR Photo 26a/04 ESO PR Photo 26a/04 The Brown Dwarf Object 2M1207 and GPCC [Preview - JPEG: 400 x 471 pix - 65k] [Normal - JPEG: 800 x 942 pix - 158k] Caption: ESO PR Photo 26a/04 is a composite image of the brown dwarf object 2M1207 (centre) and the fainter object seen near it, at an angular distance of 778 milliarcsec. Designated "Giant Planet Candidate Companion" by the discoverers, it may represent the first image of an exoplanet. Further observations, in particular of its motion in the sky relative to 2M1207 are needed to ascertain its true nature. The photo is based on three near-infrared exposures (in the H, K and L' wavebands) with the NACO adaptive-optics facility at the 8.2-m VLT Yepun telescope at the ESO Paranal Observatory. Since 1998, a team of European and American astronomers [2] is studying the environment of young, nearby "stellar associations", i.e., large conglomerates of mostly young stars and the dust and gas clouds from which they were recently formed. The stars in these associations are ideal targets for the direct imaging of sub-stellar companions (planets or brown dwarf objects). The leader of the team, ESO astronomer Gael Chauvin notes that "whatever their nature, sub-stellar objects are much hotter and brighter when young - tens of millions of years - and therefore can be more easily detected than older objects of similar mass". The team especially focused on the study of the TW

High Resolution SOFIA/EXES Spectroscopy of CH4 and SO2 toward Massive Young Stellar Objects

NASA Astrophysics Data System (ADS)

Boogert, Abraham C. A.; Richter, Matt; DeWitt, Curtis; Indriolo, Nick; Neufeld, David A.; Karska, Agata; Bergin, Edwin A.; Smith, Rachel L.; Montiel, Edward

2017-01-01

The ro-vibrational transitions of molecules in the near to mid-infrared are excellent tracers of the composition, dynamics, and excitation of the inner regions of Young Stellar Objects (YSOs). They sample a wide range of excitations in a short wavelength range, they can be seen in absorption against strong hot dust continuum sources, and they trace molecules without permanent dipole moment not observable at radio wavelengths. In particular, at high infrared spectral resolution, spatial scales smaller than those imaged by millimeter wave interferometers can be studied dynamically.We present high resolution (R=λ/Δλ˜50,000-100,000 6-12 km/s) infrared (7-8 μm) spectra of massive YSOs observed with the Echelon-Cross-Echelle Spectrograph (EXES) on the Stratospheric Observatory For Infrared Astronomy (SOFIA). Absorption lines of gas phase methane (CH4) are detected in our Cycle 2 observations. CH4 is thought to be a starting point of the formation of carbon chain molecules. Abundances are derived in the different dynamical regions along the sight-line towards the central star by comparing the line profiles to those of CO and other species observed at ground based facilities such as EXES' sister instrument TEXES at IRTF and Gemini. A search is also conducted for sulfur-dioxide, using data from our ongoing Cycle 4 program. SO2 was previously detected towards these massive YSOs with the space-based ISO/SWS instrument (Keane et al. 2001, A&A 376, L5) at much lower spectral resolution (R˜2,000). At high spectral resolution we should be able to pin-point the dynamical location of this SO2 gas. Up to 98% of the sulfur in dense clouds and protostellar envelopes is presently missing, and we are searching for that with the EXES/SOFIA observations.

Probing the Evolution of Massive Young Stellar Objects using Weak Class II 6.7GHz Methanol Maser Emission

NASA Astrophysics Data System (ADS)

Ludwig, Bethany Ann; Cunningham, Nichol

2017-01-01

We present results from an investigation of class II 6.7GHz methanol masers towards four Massive Young Stellar Objects (MYSOs). The sources, selected from the Red MSX Source (RMS) Survey (Lumsden et al. 2013), were previously understood to be non-detections for class II methanol maser emission in the methanol multi-beam (MMB) Survey (Caswell et al. 2010.) Class II methanol masers are a well-known sign post of massive star forming regions and may be utilized to probe their relatively poorly understood formation. It is possible that these non-detections are simply weak masers that are potentially associated with a younger evolutionary phase of MYSOs as hypothesized by Olmi et al. (2014). The sources were chosen to sample various stages of evolution, having similar 21 to 8 micron flux ratios and bolometric luminosities as other MYSOs with previous class II methanol maser detections. We observed all 4 MYSOs with ATCA (~2" resolution) at 10 times deeper sensitivity than previously obtained with the MMB survey and have a spectral resolution of 0.087kms^-1 . The raw data is reduced using the program Miriad (Sault, R. J., et al., 1995) and deconvolutioned using the program CASA (McMullin, J. P., et al. 2007.) We determine one of the four observed MYSOs is harboring a weak class II methanol maser. We discuss the possibility of sensitivity limitations on the remaining sources as well as environmental and evolutionary differences between the sources.

Constructing "Normal Childhoods": Young People Talk about Young Carers

ERIC Educational Resources Information Center

O'Dell, L.; Crafter, S.; de Abreu, G.; Cline, T.

2010-01-01

There has been a great deal of attention paid to young carers in recent research, social policy and service provision. In this paper we report on a survey and interview study of 46 young people aged 15 to 18, nine of whom had experience as young carers, to explore the ways in which young people construct the young carer and their disabled parent.…

The History and Timing of Depression Onset as Predictors of Young Adult Self-Esteem

ERIC Educational Resources Information Center

Gayman, Mathew D.; Lloyd, Donald A.; Ueno, Koji

2011-01-01

Depression often emerges early in the lifecourse and is consistently shown to be associated with poor self-esteem. The 3 main objectives of the current study are to (1) evaluate the association between a history major depression and self-esteem in young adulthood, (2) assess the relationship between timing of depression onset and young adult…

Young stellar objects & photoevaporating protoplanetary disks in the Orion's sibling NGC 1977.

NASA Astrophysics Data System (ADS)

Kim, J. S.; Fang, M.; Clarke, C. J.; Facchini, S.; Pascucci, I.; Apai, D.; Bally, J.

We present young stellar population in NGC 1977, Orion Nebula's sibling, and the discovery of new photoevaporating protoplanetary disks (proplyds) around a B star, 42 Ori. NGC 1977 (age≲2 Myr) is located at ˜30arcmin north of the Orion Nebula at a distance of ˜400 pc, but it lacks high mass O stars unlike in Orion Nebula Cluster (ONC). Nevertheless, we have identified seven proplyds in vicinity of its most massive star, 42 Ori (B1V). The proplyds show cometary Halpha emission in HST images, with clear ionization front and tails evaporating away from 42 Ori. These are the first proplyds to be found around a B star, while previously known proplyds were found near O stars. The FUV radiation impinging on these proplyds is 10-30 times weaker than that on the proplyds in ONC. We find that observed proplyd sizes are consistent with a model for photoevaporation in weak FUV radiation field. We briefly discuss one of the interesting YSOs found in this lesser-known star forming region in Orion, NGC 1977.

Novel end points for clinical trials in young children with cystic fibrosis.

PubMed

Simpson, Shannon J; Mott, Lauren S; Esther, Charles R; Stick, Stephen M; Hall, Graham L

2013-06-01

Cystic fibrosis (CF) lung disease commences early in the disease progression and is the most common cause of mortality. While new CF disease-modifying agents are currently undergoing clinical trial evaluation, the implementation of such trials in young children is limited by the lack of age-appropriate clinical trial end points. Advances in infant and preschool lung function testing, imaging of the chest and the development of biochemical biomarkers have led to increased possibility of quantifying mild lung disease in young children with CF and objectively monitoring disease progression over the course of an intervention. Despite this, further standardization and development of these techniques is required to provide robust objective measures for clinical trials in this age group.

Young Children's Use of Surface and Object Information in Drawings of Everyday Scenes.

PubMed

Dillon, Moira R; Spelke, Elizabeth S

2017-09-01

Pictorial symbols such as photographs, drawings, and maps are ubiquitous in modern cultures. Nevertheless, it remains unclear how children relate these symbols to the scenes that they represent. The present work investigates 4-year-old children's (N = 144) sensitivity to extended surface layouts and objects when using drawings of a room to find locations in that room. Children used either extended surfaces or objects when interpreting drawings, but they did not combine these two types of information to disambiguate target locations. Moreover, children's evaluations of drawings depicting surfaces or objects did not align with their use of such information in those drawings. These findings suggest that pictures of all kinds serve as media in which children deploy symbolic spatial skills flexibly and automatically. © 2016 The Authors. Child Development © 2016 Society for Research in Child Development, Inc.

A Calibrated H-alpha Index to Monitor Emission Line Objects

NASA Astrophysics Data System (ADS)

Hintz, Eric G.; Joner, M. D.

2013-06-01

Over an 8 year period we have developed a calibrated H-alpha index, similar to the more traditional H-beta index, based on spectrophotometric observations (Joner & Hintz, 2013) from the DAO 1.2-m Telescope. While developing the calibration for this filter set we also obtained spectra of a number of emission line systems such as high mass x-ray binaries (HMXB), Be stars, and young stellar objects. From this work we find that the main sequence stars fill a very tight relation in the H-alpha/H-beta plane and that the emission line objects are easily detected. We will present the overall location of these emission line objects. We will also present the changes experiences by these objects over the course of the years of the project.

Parenting and Violence Toward Self, Partners, and Others Among Inner-City Young Adults

PubMed Central

Stueve, Ann; Myint-U, Athi

2009-01-01

Objectives. We examined relationships between parenting status and multiple forms of violence perpetration among young adults in high-poverty environments. Methods. We analyzed data obtained from a survey of 990 young adults in New York City. Respondents reported on violence they had perpetrated toward themselves, intimate partners, and others. Associations between parenting and violence were examined in logistic regressions, controlling for sociodemographics. Results. Fewer young men (33.0%) than young women (48.6%) reported that they were raising children. Among young men, parenting was associated with violence toward themselves (odds ratio [OR] = 1.8; 95% confidence interval [CI] = 1.03, 3.16) but not with violence toward partners or others. Among young women, violence perpetration did not differ by parenting status. Correlations among forms of violence were higher among young women than among young men, especially among mothers. Community violence was associated with violence toward others for both genders. For young men, community violence was associated with violence toward partners. Conclusions. Parenting did not reduce inner-city young adults' perpetration of violence. Among fathers, parenting may be, along with unemployment, a risk for violence toward self. Understanding patterns of violence can inform interventions that support young adults, including those who are parenting, in creating nonviolent homes and communities. PMID:19833989

Objective reports versus subjective perceptions of crime and their relationships to accelerometer-measured physical activity in Hispanic caretaker-child dyads.

PubMed

van Bakergem, Margaret; Sommer, Evan C; Heerman, William J; Hipp, James Aaron; Barkin, Shari L

2017-02-01

Crime and safety are commonly cited barriers to physical activity (PA). We had three objectives, 1) describe the association between objective crime measures and perceptions of crime, 2) analyze the relationships between each type of crime and accelerometer-measured physical activity in caretakers and young children (ages 3-5years), and 3) explore for early gender differences in the relationship between crime and physical activity in young children. Data are from the cross-sectional baseline data of an ongoing randomized controlled trial in Nashville, Tennessee spanning September 2012 through May 2014. Data was analyzed from 480 Hispanic dyads (adult caretaker and 3-5year old child). Objective crime rate was assessed in ArcGIS and perception of crime was measured by caretaker agreement with the statement "The crime rate in my neighborhood makes it unsafe to go on walks." The primary outcome was accelerometer-measured physical activity over seven consecutive days. Objective and perceived crime were significantly positively correlated. Caretaker vigorous PA was significantly related to perceptions of crime; however, its relationship to objective crime was not significant. Child PA was not significantly related to caretaker perceptions of crime. However, interactions suggested that the relationship between crime rate and PA was significantly more negative for girls than for boys. Objective and subjective measures of crime rate are expected to be important correlates of PA, but they appear to have complex relationships that are different for adults than they are for young children, as well as for young girls compared to boys, and research has produced conflicting findings. Copyright © 2016 Elsevier Inc. All rights reserved.

3-D Mind Maps: Placing Young Children in the Centre of Their Own Learning

ERIC Educational Resources Information Center

Howitt, Christine

2009-01-01

Three-dimensional mind maps are a highly effective tool for providing engaging, kinaesthetic and sensory experiences for young children, with real objects used to promote the sharing of knowledge and the creation of connections. The use of real objects allows children the opportunity to connect with those objects at a personal level, thus placing…

Academic Self-Concept and Motivation in Young Talents of a Private University in Tarapoto

ERIC Educational Resources Information Center

Carranza, Renzo F.; Apaza, Effer E.

2015-01-01

The objective of this study was to determine the relationship between academic self-concept and academic motivation in young talents (Scholarship 18) at a Private University in Tarapoto city, Peru. The sample was obtained through a probabislitic sampling and there were 92 young talents, being 47.8% male and 52.2% female between 17 and 22 years…

Association Between Sexually Transmitted Diseases and Young Adults' Self-reported Abstinence

PubMed Central

DiClemente, Ralph J.; Danner, Fred; Crosby, Richard A.

2011-01-01

OBJECTIVE: Self-reported behavior has been the cornerstone of sexual health research and clinical practice, yet advances in sexually transmitted disease (STD) screening provide researchers with the opportunity to objectively quantify sexual risk behaviors. However, the extent to which young adults' laboratory-confirmed STD results and self-reported sexual behaviors are consistent has not been assessed in a nationally representative sample. PATIENTS AND METHODS: Data are derived from participants who completed wave 3 in the National Longitudinal Study of Adolescent Health. Young adults (N = 14 012) completed an audio computer-assisted self-interviewing survey and provided a urine specimen to detect the presence of Chlamydia trachomatis and Neisseria gonorrhoeae, and a polymerase chain reaction assay to detect Trichomonas vaginalis. RESULTS: More than 10% of young adults with a laboratory-confirmed positive STD result reported abstaining from sexual intercourse in the 12 months before assessment and STD testing. After controlling for several sociodemographic factors, self-reported sex (versus those who reported abstinence) in the previous 12 months was significantly associated with testing positive, but the odds of testing positive were only slightly more than twofold (adjusted odds ratio: 2.11 [95% confidence interval: 2.097–2.122]). CONCLUSIONS: Findings indicate discrepancy between young adults' positive STD status and self-reported sexual behavior. No significant correlates of discrepant reporting were identified. From a clinical standpoint, the discrepancies between STD positivity and self-reported sexual behavior observed in this nationally representative sample suggest that routine STD screening may be beneficial and necessary to reduce STD morbidity among young adults. PMID:21199852

Constraints on the spin evolution of young planetary-mass companions

NASA Astrophysics Data System (ADS)

Bryan, Marta L.; Benneke, Björn; Knutson, Heather A.; Batygin, Konstantin; Bowler, Brendan P.

2018-02-01

Surveys of young star-forming regions have discovered a growing population of planetary-mass (<13 MJup) companions around young stars1. There is an ongoing debate as to whether these companions formed like planets (that is, from the circumstellar disk)2, or if they represent the low-mass tail of the star-formation process3. In this study, we utilize high-resolution spectroscopy to measure rotation rates of three young (2-300 Myr) planetary-mass companions and combine these measurements with published rotation rates for two additional companions4,5 to provide a picture of the spin distribution of these objects. We compare this distribution to complementary rotation-rate measurements for six brown dwarfs with masses <20 MJup, and show that these distributions are indistinguishable. This suggests that either these two populations formed via the same mechanism, or that processes regulating rotation rates are independent of formation mechanism. We find that rotation rates for both populations are well below their break-up velocities and do not evolve significantly during the first few hundred million years after the end of accretion. This suggests that rotation rates are set during the late stages of accretion, possibly by interactions with a circumplanetary disk. This result has important implications for our understanding of the processes regulating the angular momentum evolution of young planetary-mass objects, and of the physics of gas accretion and disk coupling in the planetary-mass regime.

Dimensions of Problem Drinking among Young Adult Restaurant Workers

PubMed Central

Moore, Roland S.; Cunradi, Carol B.; Duke, Michael R.; Ames, Genevieve M.

2009-01-01

Background Nationwide surveys identify food service workers as heavy alcohol users. Objectives This article analyzes dimensions and correlates of problem drinking among young adult food service workers. Methods A telephone survey of national restaurant chain employees yielded 1294 completed surveys. Results Hazardous alcohol consumption patterns were seen in 80% of men and 64% of women. Multivariate analysis showed that different dimensions of problem drinking measured by the AUDIT were associated with workers' demographic characteristics, smoking behavior and job category. Conclusions & Scientific Significance These findings offer evidence of extremely high rates of alcohol misuse among young adult restaurant workers. PMID:20180660

Age, environment, object recognition and morphological diversity of GFAP-immunolabeled astrocytes.

PubMed

Diniz, Daniel Guerreiro; de Oliveira, Marcus Augusto; de Lima, Camila Mendes; Fôro, César Augusto Raiol; Sosthenes, Marcia Consentino Kronka; Bento-Torres, João; da Costa Vasconcelos, Pedro Fernando; Anthony, Daniel Clive; Diniz, Cristovam Wanderley Picanço

2016-10-10

Few studies have explored the glial response to a standard environment and how the response may be associated with age-related cognitive decline in learning and memory. Here we investigated aging and environmental influences on hippocampal-dependent tasks and on the morphology of an unbiased selected population of astrocytes from the molecular layer of dentate gyrus, which is the main target of perforant pathway. Six and twenty-month-old female, albino Swiss mice were housed, from weaning, in a standard or enriched environment, including running wheels for exercise and tested for object recognition and contextual memories. Young adult and aged subjects, independent of environment, were able to distinguish familiar from novel objects. All experimental groups, except aged mice from standard environment, distinguish stationary from displaced objects. Young adult but not aged mice, independent of environment, were able to distinguish older from recent objects. Only young mice from an enriched environment were able to distinguish novel from familiar contexts. Unbiased selected astrocytes from the molecular layer of the dentate gyrus were reconstructed in three-dimensions and classified using hierarchical cluster analysis of bimodal or multimodal morphological features. We found two morphological phenotypes of astrocytes and we designated type I the astrocytes that exhibited significantly higher values of morphological complexity as compared with type II. Complexity = [Sum of the terminal orders + Number of terminals] × [Total branch length/Number of primary branches]. On average, type I morphological complexity seems to be much more sensitive to age and environmental influences than that of type II. Indeed, aging and environmental impoverishment interact and reduce the morphological complexity of type I astrocytes at a point that they could not be distinguished anymore from type II. We suggest these two types of astrocytes may have different physiological roles

Dwarfs on a Low-Carbon Diet: Modelling the Chemically Peculiar Secondaries of CVs

NASA Astrophysics Data System (ADS)

Homeier, D.; Harrison, T. E.; Barman, T. S.; Howell, S. B.

2003-12-01

Secondary stars of cataclysmic variables show a variety of abundance anomalies that might be caused by deposition of CNO-processed material. We have calculated PHOENIX stellar atmosphere models for late-type stellar and substellar companions using chemical equilibrium compositions for a range of carbon-depleted and/or oxygen-enriched elemental abundances. We present comparisons of our models with medium-resolution IR spectra of CV secondaries, including the possibly substellar secondary of the EF Eridani system. LTE models of the K-band spectrum are consistent with a Teff in the brown dwarf range and show that the complete lack of CH4 and CO absorption features in this object requires a [C/Fe] ratio more than 2 dex below the solar value. We compare our models to temperature estimates from light curve analyses and present a first irradiated model of the secondary, that takes into account the effect of the impinging flux from the white dwarf primary. This project has been supported by grants from the National Science Foundation and the NASA NStars program.

Astronaut John Young leaps from lunar surface to salute flag

NASA Technical Reports Server (NTRS)

1972-01-01

Astronaut John W. Young, commander of the Apollo 16 lunar landing mission, leaps from the lunar surface as he salutes the U.S. Flag at the Descartes landing site during the first Apollo 16 extravehicular activity (EVA-1). Astronaut Charles M. Duke Jr., lunar module pilot, took this picture. The Lunar Module (LM) 'Orion' is on the left. The Lunar Roving Vehicle is parked beside the LM. The object behind Young in the shade of the LM is the Far Ultraviolet Camera/Spectrograph. Stone Mountain dominates the background in this lunar scene.

Planet Formation in Action? - Astronomers may have found the first object clearing its path in the natal disc surrounding a young star

NASA Astrophysics Data System (ADS)

2011-02-01

Using ESO's Very Large Telescope an international team of astronomers has been able to study the short-lived disc of material around a young star that is in the early stages of making a planetary system. For the first time a smaller companion could be detected that may be the cause of the large gap found in the disc. Future observations will determine whether this companion is a planet or a brown dwarf. Planets form from the discs of material around young stars, but the transition from dust disc to planetary system is rapid and few objects are caught during this phase [1]. One such object is T Chamaeleontis (T Cha), a faint star in the small southern constellation of Chamaeleon that is comparable to the Sun, but very near the beginning of its life [2]. T Cha lies about 350 light-years from the Earth and is only about seven million years old. Up to now no forming planets have been found in these transitional discs, although planets in more mature discs have been seen before (eso0842, heic0821). "Earlier studies had shown that T Cha was an excellent target for studying how planetary systems form," notes Johan Olofsson (Max Planck Institute for Astronomy, Heidelberg, Germany), one of the lead authors of two papers in the journal Astronomy & Astrophysics that describe the new work. "But this star is quite distant and the full power of the Very Large Telescope Interferometer (VLTI) was needed to resolve very fine details and see what is going on in the dust disc." The astronomers first observed T Cha using the AMBER instrument and the VLT Interferometer (VLTI) [3]. They found that some of the disc material formed a narrow dusty ring only about 20 million kilometres from the star. Beyond this inner disc, they found a region devoid of dust with the outer part of the disc stretching out into regions beyond about 1.1 billion kilometres from the star. Nuria Huélamo (Centro de Astrobiología, ESAC, Spain), the lead author of the second paper takes up the story: "For us the

Longitudinal Impact of Attachment-Related Risk and Exposure to Trauma among Young Children after Hurricane Katrina

ERIC Educational Resources Information Center

Osofsky, Joy; Kronenberg, Mindy; Bocknek, Erika; Hansel, Tonya Cross

2015-01-01

Background: Research suggests that young childhood is a dynamic developmental phase during which risks to attachment figures as well as traumatic events may be particularly important. The loss and disruption associated with Hurricane Katrina highlighted the vulnerabilities and special needs of young children exposed to natural disaster. Objective:…

A Structural Analysis on Korean Young Children's Mathematical Ability and Its Related Children's and Mothers' Variables

ERIC Educational Resources Information Center

Lee, Hye Jung; Kim, Jihyun

2016-01-01

The objective of this study is to examine the structural relationships among variables that predict the mathematical ability of young children, namely young children's mathematical attitude, exposure to private mathematical learning, mothers' view about their children's mathematical learning, and mothers' mathematical attitude. To this end, we…

Animal spotting in Alzheimer's disease: an eye tracking study of object categorization.

PubMed

Boucart, Muriel; Bubbico, Giovanna; Szaffarczyk, Sébastien; Pasquier, Florence

2014-01-01

We investigated rapid object categorization and, more specifically, the ability to detect a target object within a natural scene in people with mild Alzheimer's disease (AD) using a saccadic choice task. It has been suggested that the anatomical pathway likely used to initiate rapid oculomotor responses in the saccadic choice task could involve the Frontal Eye Field, a structure that is part of the dorsal attentional network, in which connectivity is disrupted in AD. Seventeen patients with mild AD and 23 healthy age-matched controls took part in the study. A group of 24 young healthy observers was included as it has been reported that normal aging affects eye movements. Participants were presented with pairs of colored photographs of natural scenes, one containing an animal (the target) and one containing various objects (distracter), displayed for 1 s left and right of fixation. They were asked to saccade to the scene containing an animal. Neither pathology nor age affected temporal (saccade latencies and durations) and spatial (saccade amplitude) parameters of eye movements. Patients with AD were significantly less accurate than age-matched controls, and older participants were less accurate than young observers. The results are interpreted in terms of noisier sensory information and increased uncertainty in relation to deficits in the magnocellular pathway. The results suggest that, even at a mild stage of the pathology, people exhibit difficulties in selecting relevant objects.

Gravitational Instabilities in a Young Protoplanetary Disk with Embedded Objects

NASA Astrophysics Data System (ADS)

Desai, Karna M.

Gravitational Instabilities (GIs), a mechanism for angular momentum transport, are prominent during the early phases of protoplanetary disk evolution when the disk is relatively massive. In this dissertation, I analyze GIs by inserting different objects in a disk by employing 3D hydrodynamics simulations. GIs in a circumbinary disks are studied to determine how the presence of the companion affects the nature and strength of GIs in the disk. The circumbinary disk achieves a state of sustained marginal instability similar to an identical disk without the companion. A realistic evolution of the binary is detected. Planet and disk interactions play an important role in the evolution of planetary systems. To study this interaction during the early phases of planet formation, a migration study of Jovian planets in a GI-active disk is conducted. I find the migration timescales to be longer in a GI-active disk, when compared to laminar disks. The 3 MJupiter planet controls its own orbital evolution, while the migration of a 0.3 MJupiter planet is stochastic in nature. I define a 'critical mass' as the mass of an arm of the dominant two-armed spiral density wave within the planet's Hill diameter. Planets above this mass control their own destiny, and planets below this mass are scattered by the disk. This critical mass could provide a recipe for predicting the migration behavior of planets in GI-active disks. To understand the stochastic migration of low-mass planets, I perform a simulation of 240 zero-mass planet-tracers by inserting these at a range of locations in the disk. A Diffusion Coefficient is calculated to characterize the stochastic migration of low-mass objects. The eccentricity dispersion for the sample is also studied. I find that the diffusion of planets can be a slow process, resulting in the survival of small planetary cores.

Young people have their say: What makes a youth-friendly general practice?

PubMed

Turner, Laura; Spencer, Leah; Strugnell, Jack; Di Tommaso, Isabel; Tate, Magella; Allen, Penny; Cheek, Colleen; Cooper, Jane; Chang, Julian

The health of young people can be considered an indicator of the health of Australia's future population. To improve access to healthcare, the perspectives of adolescents on the design and delivery of services need to be championed. The objective of this study was to identify what young people in north-west Tasmania value when seeking healthcare at general practices. The study was conducted at a single high school in rural Tasmania. Students aged 16-18 years were invited to participate in an electronic survey seeking their views and preferences for presenting to their general practitioner (GP). One hundred and fifty-five students, with a mean age of 17 years, were surveyed. GPs were the usual healthcare providers for 98.4% of participants, and 86% stated that they would like to discuss mental health, substance use and sexual health with their GP. GPs can improve access to care for young people through good communications skills and treating young people as young adults.

Safety margins in older adults increase with improved control of a dynamic object

PubMed Central

Hasson, Christopher J.; Sternad, Dagmar

2014-01-01

Older adults face decreasing motor capabilities due to pervasive neuromuscular degradations. As a consequence, errors in movement control increase. Thus, older individuals should maintain larger safety margins than younger adults. While this has been shown for object manipulation tasks, several reports on whole-body activities, such as posture and locomotion, demonstrate age-related reductions in safety margins. This is despite increased costs for control errors, such as a fall. We posit that this paradox could be explained by the dynamic challenge presented by the body or also an external object, and that age-related reductions in safety margins are in part due to a decreased ability to control dynamics. To test this conjecture we used a virtual ball-in-cup task that had challenging dynamics, yet afforded an explicit rendering of the physics and safety margin. The hypotheses were: (1) When manipulating an object with challenging dynamics, older adults have smaller safety margins than younger adults. (2) Older adults increase their safety margins with practice. Nine young and 10 healthy older adults practiced moving the virtual ball-in-cup to a target location in exactly 2 s. The accuracy and precision of the timing error quantified skill, and the ball energy relative to an escape threshold quantified the safety margin. Compared to the young adults, older adults had increased timing errors, greater variability, and decreased safety margins. With practice, both young and older adults improved their ability to control the object with decreased timing errors and variability, and increased their safety margins. These results suggest that safety margins are related to the ability to control dynamics, and may explain why in tasks with simple dynamics older adults use adequate safety margins, but in more complex tasks, safety margins may be inadequate. Further, the results indicate that task-specific training may improve safety margins in older adults. PMID:25071566

Perceived Effectiveness of Tobacco Countermarketing Advertisements among Young Adults

ERIC Educational Resources Information Center

Murphy-Hoefer, Rebecca; Hyland, Andrew; Higbee, Cheryl

2008-01-01

Objectives: To measure relative effectiveness of tobacco countermarketing advertisements by category and emotive execution style among young adults. Methods: Participants (n = 1011) from 2 US 4-year colleges, one southern and one northern were surveyed before and after viewing advertisements in one of 3 categories: social norms, health…

Is Pubertal Timing Associated with Psychopathology in Young Adulthood?

ERIC Educational Resources Information Center

Graber, Julia A.; Seeley, John R.; Brooks-Gunn, Jeanne; Lewinsohn, Peter M.

2004-01-01

Objective: This investigation tested whether the timing of puberty continued to be associated with experiences of psychopathology (symptoms and disorders) from mid-adolescence into young adulthood. Method: At age 24, 931 participants from a large community sample, who had been interviewed twice during adolescence, completed a telephone interview…

Object permanence development in infants with motor handicaps.

PubMed

Fetters, L

1981-03-01

This study was an investigation of the effects of a motor handicap on the development of object permanence in the young child. Motor abilities were evaluated for 12 infants aged 13 to 29 months. Based on this evaluation, the children were described as manipulators or nonmanipulators in reference to their upper extremity skills. Their stage of object permanence was assessed using traditional and nontraditional assessments. Heart rate and visual tracking were recorded during the nontraditional assessment. Heart rate did not significantly relate to visual fixation or search response. There was, however, a significant difference (p less than .02) between stage achievement with traditional testing and age-appropriate levels. There was no significant difference between the nontraditional assessment and the age-appropriate levels. In addition, there was no significant difference in the development of object permanence between infants described as manipulators and those described as nonmanipulators. The last two findings suggest that infants with motor handicaps may develop object permanence at the expected ages, according to a nontraditional assessment.

SEARCHING FOR YOUNG M DWARFS WITH GALEX

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shkolnik, Evgenya L.; Weinberger, Alycia J.; Liu, Michael C.

2011-01-20

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 {approx}>K5 (R - J {approx}> 1.5) and younger than {approx}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 (HSTmore » Guide Star Catalog) and near-IR (2MASS) photometry, we identified an initial sample of 34 young M dwarf candidates in a 1000 deg{sup 2} region around the {approx}10 Myr TW Hydra Association (TWA). Low-resolution spectroscopy of 30 of these found 16 which had H{alpha} 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 {approx}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{sup -1}) H{alpha} emission, making it the sixth member of TWA found to have ongoing accretion. TWA 32 is resolved into a 0.''6 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

Articulation Rate and Vowel Space Characteristics of Young Males with Fragile X Syndrome: Preliminary Acoustic Findings

ERIC Educational Resources Information Center

Zajac, David J.; Roberts, Joanne E.; Hennon, Elizabeth A.; Harris, Adrianne A.; Barnes, Elizabeth F.; Misenheimer, Jan

2006-01-01

Purpose: Increased speaking rate is a commonly reported perceptual characteristic among males with fragile X syndrome (FXS). The objective of this preliminary study was to determine articulation rate--one component of perceived speaking rate--and vowel space characteristics of young males with FXS. Method: Young males with FXS (n = 38), …

New White Dwarf-Brown Dwarf Binaries

NASA Astrophysics Data System (ADS)

Casewell, S. L.; Geier, S.; Lodieu, N.

2017-03-01

We present follow-up spectroscopy to 12 candidate white dwarf-brown dwarf binaries. We have confirmed that 8 objects do indeed have a white dwarf primary (7 DA, 1 DB) and two are hot subdwarfs. We have determined the Teff and log g for the white dwarfs and subdwarfs, and when combining these values with a model spectrum and the photometry, we have 3 probable white dwarf-substellar binaries with spectral types between M6 and L6.

Decreased attention to object size information in scale errors performers.

PubMed

Grzyb, Beata J; Cangelosi, Angelo; Cattani, Allegra; Floccia, Caroline

2017-05-01

Young children sometimes make serious attempts to perform impossible actions on miniature objects as if they were full-size objects. The existing explanations of these curious action errors assume (but never explicitly tested) children's decreased attention to object size information. This study investigated the attention to object size information in scale errors performers. Two groups of children aged 18-25 months (N=52) and 48-60 months (N=23) were tested in two consecutive tasks: an action task that replicated the original scale errors elicitation situation, and a looking task that involved watching on a computer screen actions performed with adequate to inadequate size object. Our key finding - that children performing scale errors in the action task subsequently pay less attention to size changes than non-scale errors performers in the looking task - suggests that the origins of scale errors in childhood operate already at the perceptual level, and not at the action level. Copyright © 2017 Elsevier Inc. All rights reserved.

Acute Stress Symptoms in Young Children with Burns

ERIC Educational Resources Information Center

Stoddard, Frederick J.; Saxe, Glenn; Ronfeldt, Heidi; Drake, Jennifer E.; Burns, Jennifer; Edgren, Christy; Sheridan, Robert

2006-01-01

Objective: Posttraumatic stress disorder symptoms are a focus of much research with older children, but little research has been conducted with young children, who account for about 50% of all pediatric burn injuries. This is a 3-year study of 12- to 48-month-old acutely burned children to assess acute traumatic stress outcomes. The aims were to…

Binary Populations and Stellar Dynamics in Young Clusters

NASA Astrophysics Data System (ADS)

Vanbeveren, D.; Belkus, H.; Van Bever, J.; Mennekens, N.

2008-06-01

We first summarize work that has been done on the effects of binaries on theoretical population synthesis of stars and stellar phenomena. Next, we highlight the influence of stellar dynamics in young clusters by discussing a few candidate UFOs (unconventionally formed objects) like intermediate mass black holes, η Car, ζ Pup, γ2 Velorum and WR 140.

Interventions for Young Bereaved Children: A Systematic Review and Implications for School Mental Health Providers

ERIC Educational Resources Information Center

Chen, Cliff Yung-Chi; Panebianco, Andrea

2018-01-01

Background: Many young children experience the death of a family member and they may be at risk for developing psychological and behavioral problems, but not much is known about how to help young children cope with such a stressful and painful experience. Objective: The purposes of this study are to identify the interventions for bereaved young…

A companion candidate in the gap of the T Chamaeleontis transitional disk

NASA Astrophysics Data System (ADS)

Huélamo, N.; Lacour, S.; Tuthill, P.; Ireland, M.; Kraus, A.; Chauvin, G.

2011-04-01

Context. T Cha is a young star surrounded by a cold disk. The presence of a gap within its disk, inferred from fitting to the spectral energy distribution, has suggested on-going planetary formation. Aims: The aim of this work is to look for very low-mass companions within the disk gap of T Cha. Methods: We observed T Cha in L' and Ks with NAOS-CONICA, the adaptive optics system at the VLT, using sparse aperture masking. Results: We detected a source in the L' data at a separation of 62 ± 7 mas, position angle of ~78 ± 1 degrees, and a contrast of ΔL' = 5.1 ± 0.2 mag. The object is not detected in the Ks band data, which show a 3-σ contrast limit of 5.2 mag at the position of the detected L' source. For a distance of 108 pc, the detected companion candidate is located at 6.7 AU from the primary, well within the disk gap. If T Cha and the companion candidate are bound, the comparison of the L' and Ks photometry with evolutionary tracks shows that the photometry is inconsistent with any unextincted photosphere at the age and distance of T Cha. The detected object shows a very red Ks - L' color, for which a possible explanation would be a significant amount of dust around it. This would imply that the companion candidate is young, which would strengthen the case for a physical companion, and moreover that the object would be in the substellar regime, according to the Ks upper limit. Another exciting possibility would be that this companion is a recently formed planet within the disk. Additional observations are mandatory to confirm that the object is bound and to properly characterize it. Based on observations obtained at the European Southern Observatory using the Very Large Telescope in Cerro Paranal, Chile, under program 84.C-0755(A).

Age-Related Impairments in Object-Place Associations Are Not Due to Hippocampal Dysfunction

PubMed Central

Hernandez, Abigail R.; Maurer, Andrew P.; Reasor, Jordan E.; Turner, Sean M.; Barthle, Sarah E.; Johnson, Sarah A.; Burke, Sara N.

2016-01-01

Age-associated cognitive decline can reduce an individual’s quality of life. As no single neurobiological deficit can account for the wide spectrum of behavioral impairments observed in old age, it is critical to develop an understanding of how interactions between different brain regions change over the life span. The performance of young and aged animals on behaviors that require the hippocampus and cortical regions to interact, however, has not been well characterized. Specifically, the ability to link a spatial location with specific features of a stimulus, such as object identity, relies on the hippocampus, perirhinal and prefrontal cortices. Although aging is associated with dysfunction in each of these brain regions, behavioral measures of functional change within the hippocampus, perirhinal and prefrontal cortices in individual animals are often not correlated. Thus, how dysfunction of a single brain region within this circuit, such as the hippocampus, impacts behaviors that require communication with the perirhinal and prefrontal cortices remains unknown. To address this question, young and aged rats were tested on the interregion dependent object-place paired association task, as well as a hippocampal-dependent test of spatial reference memory. This particular cohort of aged rats did not show deficits on the hippocampal-dependent task, but were significantly impaired at acquiring object-place associations relative to young. These data suggest that behaviors requiring functional connectivity across different regions of the memory network may be particularly sensitive to aging, and can be used to develop models that will clarify the impact of systems-level dysfunction in the elderly. PMID:26413723

Cognitive impairment and medial temporal lobe structure in young adults with a depressive episode.

PubMed

Donix, Markus; Haussmann, Robert; Helling, Franziska; Zweiniger, Anne; Lange, Jan; Werner, Annett; Donix, Katharina L; Brandt, Moritz D; Linn, Jennifer; Bauer, Michael; Buthut, Maria

2018-09-01

Cognitive deficits are common in patients with a depressive episode although the predictors for their development and severity remain elusive. We investigated whether subjective and objective cognitive impairment in young depressed adults would be associated with cortical thinning in medial temporal subregions. High-resolution magnetic resonance imaging, cortical unfolding data analysis, and comprehensive assessments of subjective and objective cognitive abilities were performed on 27 young patients with a depressive episode (mean age: 29.0 ± 5.8 years) and 23 older participants without a history of a depressive disorder but amnestic mild cognitive impairment (68.5 ± 6.6 years) or normal cognition (65.2 ± 8.7 years). Thickness reductions in parahippocampal, perirhinal and fusiform cortices were associated with subjective memory deficits only among young patients with a depressive episode and a measurable cognitive impairment. Long-term longitudinal data would be desirable to determine the trajectories of cognitive impairment associated with depression in patients with or without cortical structure changes. The presence of clinically significant cognitive deficits in young people with a depressive episode may identify a patient population with extrahippocampal cortical thinning. Copyright © 2018 Elsevier B.V. All rights reserved.

Repetition across Successive Sentences Facilitates Young Children's Word Learning

ERIC Educational Resources Information Center

Schwab, Jessica F.; Lew-Williams, Casey

2016-01-01

Young children who hear more child-directed speech (CDS) tend to have larger vocabularies later in childhood, but the specific characteristics of CDS underlying this link are currently underspecified. The present study sought to elucidate how the structure of language input boosts learning by investigating whether repetition of object labels in…