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Sample records for lambda orionis cluster

  1. The Lambda Orionis association. [star cluster anomalies

    NASA Technical Reports Server (NTRS)

    Murdin, P.; Penston, M. V.

    1977-01-01

    The Lambda Orionis association has the photometric properties of a typical young cluster with an age of about 4 million yr. Its distance is 400 + or - 40 pc. Attention is drawn to the lack of a dense molecular cloud and associated infrared sources in this young grouping

  2. SPITZER OBSERVATIONS OF THE {lambda} ORIONIS CLUSTER. II. DISKS AROUND SOLAR-TYPE AND LOW-MASS STARS

    SciTech Connect

    Hernandez, Jesus; Morales-Calderon, Maria; Calvet, Nuria; Hartmann, L.; Muzerolle, J.; Gutermuth, R.; Luhman, K. L.; Stauffer, J. E-mail: muzerol@stsci.ed

    2010-10-20

    We present IRAC/MIPS Spitzer Space Telescope observations of the solar-type and the low-mass stellar population of the young ({approx}5 Myr) {lambda} Orionis cluster. Combining optical and Two Micron All Sky Survey photometry, we identify 436 stars as probable members of the cluster. Given the distance (450 pc) and the age of the cluster, our sample ranges in mass from 2 M{sub sun} to objects below the substellar limit. With the addition of the Spitzer mid-infrared data, we have identified 49 stars bearing disks in the stellar cluster. Using spectral energy distribution slopes, we place objects in several classes: non-excess stars (diskless), stars with optically thick disks, stars with 'evolved disks' (with smaller excesses than optically thick disk systems), and 'transitional disk' candidates (in which the inner disk is partially or fully cleared). The disk fraction depends on the stellar mass, ranging from {approx}6% for K-type stars (R{sub C} - J < 2) to {approx}27% for stars with spectral-type M5 or later (R{sub C} - J>4). We confirm the dependence of disk fraction on stellar mass in this age range found in other studies. Regarding clustering levels, the overall fraction of disks in the {lambda} Orionis cluster is similar to those reported in other stellar groups with ages normally quoted as {approx}5 Myr.

  3. SPITZER OBSERVATIONS OF THE lambda ORIONIS CLUSTER. I. THE FREQUENCY OF YOUNG DEBRIS DISKS AT 5 Myr

    SciTech Connect

    Hernandez, Jesus; Calvet, Nuria; Hartmann, L.; Muzerolle, J.; Gutermuth, R.; Stauffer, J.

    2009-12-10

    We present IRAC/MIPS Spitzer observations of intermediate-mass stars in the 5 Myr old lambda Orionis cluster. In a representative sample of stars earlier than F5 (29 stars), we find a population of nine stars with varying degree of moderate 24 mum excess comparable to those produced by debris disks in older stellar groups. As expected in debris disks systems, those stars do not exhibit emission lines in their optical spectra. We also include in our study the star HD 245185, a known Herbig Ae object which displays excesses in all Spitzer bands and shows emission lines in its spectrum. We compare the disk population in the lambda Orionis cluster with the disk census in other stellar groups studied using similar methods to detect and characterize their disks and spanning a range of ages from 3 Myr to 10 Myr. We find that for stellar groups of 5 Myr or older the observed disk frequency in intermediate-mass stars (with spectral types from late B to early F) is higher than in low-mass stars (with spectral types K and M). This is in contradiction with the observed trend for primordial disk evolution, in which stars with higher stellar masses dissipate their primordial disks faster. At 3 Myr, the observed disk frequency in intermediate-mass stars is still lower than for low-mass stars indicating that second generation dusty disks start to dominate the disk population at 5 Myr for intermediate-mass stars. This result agrees with recent models of evolution of solids in the region of the disk where icy objects form (>30 AU), which suggest that at 5-10 Myr collisions start to produce large amount of dust during the transition from runaway to oligarchic growth (reaching sizes of approx500 km) and then dust production peaks at 10-30 Myr, when objects reach their maximum size (>=1000 km).

  4. A WIYN Lithium Survey for Young Stars Near lambda Orionis

    NASA Astrophysics Data System (ADS)

    Mathieu, R. D.; Dolan, C. J.

    1999-09-01

    We have used the WIYN Multi-Object Spectrograph to test 537 stars within 0.5 deg of the lambda Orionis OB association for the presence of lithium 6708{ Angstroms} absorption, a diagnostic of youth. These stars were selected as a complete sample of pre-main-sequence candidates in the region, based on our CCD photometric survey. We find 72 stars which show large lithium equivalent widths and radial velocities consistent with association membership, only two of which were previously discovered by Hα surveys. Comparison with evolutionary models indicate that these stars have an age distribution either younger than (D'Antona & Mazzitelli 1998) or coeval with (Baraffe et al. 1998) the 2-6 Myr OB stars, and that they are roughly 0.3-1.0 M_sun. Kinematic evidence and the shape of the age distributions suggest that an event about a million years ago has strongly affected the star formation history of the region. Estimating our sample completeness at about 80%, we find that the local initial mass function within 7 parsecs of the 11 OB stars is indistinguishable from the IMF of the field. Finally, despite their youth, only four of these stars have T Tauri-like Hα emission, suggesting an absence of accretion disks. This absence may be indicative of photoevaporation of the disks due to close proximity with the OB stars. This work is supported by NSF grant AST 94-1715 and the Wisconsin Space Grant Consortium.

  5. A spectroscopic census in young stellar regions: the σ Orionis cluster

    SciTech Connect

    Hernández, Jesús; Perez, Alice; Hernan, Ramírez; Calvet, Nuria; Hartmann, Lee; Briceño, Cesar; Olguin, Lorenzo; Contreras, Maria E.; Allen, Lori; Espaillat, Catherine

    2014-10-10

    We present a spectroscopic survey of the stellar population of the σ Orionis cluster. We have obtained spectral types for 340 stars. Spectroscopic data for spectral typing come from several spectrographs with similar spectroscopic coverage and resolution. More than half of the stars in our sample are members confirmed by the presence of lithium in absorption, strong Hα in emission or weak gravity-sensitive features. In addition, we have obtained high-resolution (R ∼ 34,000) spectra in the Hα region for 169 stars in the region. Radial velocities were calculated from this data set. The radial velocity distribution for members of the cluster is in agreement with previous work. Analysis of the profile of the Hα line and infrared observations reveals two binary systems or fast rotators that mimic the Hα width expected in stars with accretion disks. On the other hand, there are stars with optically thick disks and narrow Hα profiles not expected in stars with accretion disks. This contribution constitutes the largest homogeneous spectroscopic data set of the σ Orionis cluster to date.

  6. A SCUBA-2 850-micron Survey of Circumstellar Disks in the λ Orionis Cluster

    NASA Astrophysics Data System (ADS)

    Ansdell, Megan; Williams, Jonathan P.; Cieza, Lucas A.

    2015-06-01

    We present results from an 850 μm survey of the ˜5 Myr old λ Orionis star-forming region. We used the SCUBA-2 camera on the James Clerk Maxwell Telescope to survey a ˜0.°5-diameter circular region containing 36 (out of 59) cluster members with infrared excesses indicative of circumstellar disks. We detected only one object at \\gt 3σ significance, the Herbig Ae star HD 245185, with a flux density of ˜74 mJy beam-1 corresponding to a dust mass of ˜150 {M}\\oplus . Stacking the individually undetected sources did not produce a significant mean signal but gives an upper limit on the average dust mass for λ Orionis disks of ˜3 {M}\\oplus . Our follow-up observations of HD 245185 with the Submillimeter Array found weak CO 2-1 line emission with an integrated flux of ˜170 mJy km s-1 but no 13CO or C18O isotopologue emission at 30 mJy km s-1 sensitivity, suggesting a gas mass of ≲ 1 M{}{Jup}. The implied gas-to-dust ratio is thus ≳ 50 times lower than the canonical interstellar medium value, setting HD 245185 apart from other Herbig Ae disks of similar age, which have been found to be gas rich; as HD 245185 also shows signs of accretion, we may be catching it in the final phases of disk clearing. Our study of the λ Orionis cluster places quantitative constraints on planet formation timescales, indicating that at ˜5 Myr the average disk no longer has sufficient dust and gas to form giant planets and perhaps even super-Earths; the bulk material has been mostly dispersed or is locked in pebbles/planetesimals larger than a few mm in size.

  7. A SCUBA-2 850-micron Survey of Circumstellar Disks in the λ Orionis Cluster

    NASA Astrophysics Data System (ADS)

    Ansdell, Megan; Williams, Jonathan P.; Cieza, Lucas A.

    2015-06-01

    We present results from an 850 μm survey of the ∼5 Myr old λ Orionis star-forming region. We used the SCUBA-2 camera on the James Clerk Maxwell Telescope to survey a ∼0.°5-diameter circular region containing 36 (out of 59) cluster members with infrared excesses indicative of circumstellar disks. We detected only one object at \\gt 3σ significance, the Herbig Ae star HD 245185, with a flux density of ∼74 mJy beam‑1 corresponding to a dust mass of ∼150 {M}\\oplus . Stacking the individually undetected sources did not produce a significant mean signal but gives an upper limit on the average dust mass for λ Orionis disks of ∼3 {M}\\oplus . Our follow-up observations of HD 245185 with the Submillimeter Array found weak CO 2–1 line emission with an integrated flux of ∼170 mJy km s‑1 but no 13CO or C18O isotopologue emission at 30 mJy km s‑1 sensitivity, suggesting a gas mass of ≲ 1 M{}{Jup}. The implied gas-to-dust ratio is thus ≳ 50 times lower than the canonical interstellar medium value, setting HD 245185 apart from other Herbig Ae disks of similar age, which have been found to be gas rich; as HD 245185 also shows signs of accretion, we may be catching it in the final phases of disk clearing. Our study of the λ Orionis cluster places quantitative constraints on planet formation timescales, indicating that at ∼5 Myr the average disk no longer has sufficient dust and gas to form giant planets and perhaps even super-Earths; the bulk material has been mostly dispersed or is locked in pebbles/planetesimals larger than a few mm in size.

  8. NEW ISOLATED PLANETARY-MASS OBJECTS AND THE STELLAR AND SUBSTELLAR MASS FUNCTION OF THE {sigma} ORIONIS CLUSTER

    SciTech Connect

    Pena Ramirez, K.; Bejar, V. J. S.; Petr-Gotzens, M. G. E-mail: vbejar@iac.es E-mail: ege@cab.inta-csic.es

    2012-07-20

    We report on our analysis of the VISTA Orion ZY JHK{sub s} photometric data (completeness magnitudes of Z = 22.6 and J = 21.0 mag) focusing on a circular area of 2798.4 arcmin{sup 2} around the young {sigma} Orionis star cluster ({approx}3 Myr, {approx}352 pc, and solar metallicity). The combination of the VISTA photometry with optical, WISE and Spitzer data allows us to identify a total of 210 {sigma} Orionis member candidates with masses in the interval 0.25-0.004 M{sub Sun }, 23 of which are new planetary-mass object findings. These discoveries double the number of cluster planetary-mass candidates known so far. One object has colors compatible with a T spectral type. The {sigma} Orionis cluster harbors about as many brown dwarfs (69, 0.072-0.012 M{sub Sun }) and planetary-mass objects (37, 0.012-0.004 M{sub Sun }) as very low mass stars (104, 0.25-0.072 M{sub Sun }). Based on Spitzer data, we derive a disk frequency of {approx}40% for very low mass stars, brown dwarfs, and planetary-mass objects in {sigma} Orionis. The radial density distributions of these three mass intervals are alike: all are spatially concentrated within an effective radius of 12' (1.2 pc) around the multiple star {sigma} Ori, and no obvious segregation between disk-bearing and diskless objects is observed. Using the VISTA data and the Mayrit catalog, we derive the cluster mass spectrum ({Delta}N/{Delta}M {approx} M{sup -{alpha}}) from {approx}19 to 0.006 M{sub Sun} (VISTA ZJ completeness), which is reasonably described by two power-law expressions with indices of {alpha} = 1.7 {+-} 0.2 for M > 0.35 M{sub Sun }, and {alpha} = 0.6 {+-} 0.2 for M < 0.35 M{sub Sun }. The {sigma} Orionis mass spectrum smoothly extends into the planetary-mass regime down to 0.004 M{sub Sun }. Our findings of T-type sources (<0.004 M{sub Sun }) in the VISTA {sigma} Orionis exploration appear to be smaller than what is predicted by the extrapolation of the cluster mass spectrum down to the survey J

  9. Characterization of the known T-type dwarfs towards the σ Orionis cluster

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    Aims: The detailed study of T-type candidate members of the young σ Orionis cluster (~3 Myr, ~352 pc, solar metallicity) is fundamental to properly assess the objects' cluster membership and their contribution to the definition of the substellar mass function. Methods: A total of three T-type candidates (S Ori 70, S Ori 73, and S Ori J053804.65-021352.5) lying in the line of sight towards σ Orionis were characterized by means of near-infrared photometric, astrometric, and spectroscopic studies. H-band methane images were collected for all three sources and an additional sample of 15 field T-type dwarfs using the LIRIS instrument on the 4.2 m William Herschel Telescope (WHT). J-band spectra of resolution of ~500 were obtained for S Ori J053804.65-021352.5 with the ISAAC spectrograph on the 8 m Very Large Telescope (VLT), and JH spectra of resolution of ~50 acquired with the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope (HST) were employed for the spectroscopic classification of S Ori 70 and 73. Accurate proper motions with a typical uncertainty of ±3 mas yr-1 and a time interval of ~7-9 yr were derived using old images and new data collected with ISAAC/VLT and WFC3/HST. Results: Using the LIRIS observations of the field T dwarfs, we calibrated this imager for T spectral typing via methane photometry. The three S Ori objects were spectroscopically classified as T4.5 ± 0.5 (S Ori 73), T5 ± 0.5 (S Ori J053804.65-021352.5), and T7 +0.5-1.0 (S Ori 70). These spectral types agree with the measured H-band methane colors. The similarity between the observed JH spectra and the methane colors and the data of field ultra-cool dwarfs of related classifications suggests that S Ori 70, 73, and S Ori J053804.65-021352.5 do not deviate significantly in surface gravity in relation to the field. Additionally, the detection of K I at ~1.25 μm in S Ori J053804.65-021352.5 points to a high-gravity atmosphere. Only the K-band reddish nature of S Ori 70 may be

  10. A deep look into the core of young clusters. II. λ-Orionis

    NASA Astrophysics Data System (ADS)

    Bouy, H.; Huélamo, N.; Barrado Y Navascués, D.; Martín, E. L.; Petr-Gotzens, M. G.; Kolb, J.; Marchetti, E.; Morales-Calderón, M.; Bayo, A.; Artigau, E.; Hartung, M.; Marchis, F.; Tamura, M.; Sterzik, M.; Köhler, R.; Ivanov, V. D.; Nürnberger, D.

    2009-09-01

    Context: Over the past years, the λ-Orionis cluster has been a prime location for the study of young very low mass stars, substellar and isolated planetary mass objects and the determination of the initial mass function and other properties of low mass cluster members. Aims: In the continuity of our previous studies of young associations cores, we search for ultracool members and new multiple systems within the central 5.3 arcmin (≈0.6 pc) of the cluster. Methods: We obtained deep seeing limited J, Ks-band images of the 5.3 arcmin central part of the cluster with NTT/SofI and H-band images with CAHA/Omega2000. These images were complemented by multi-conjugate adaptive optics (MCAO) H and Ks images of the 1.5 arcmin central region of the λ-Orionis cluster obtained with the prototype MCAO facility MAD at the VLT. The direct vicinity of the massive λ-Ori O8III-star was probed using NACO/SDI at the VLT. Finally, we also retrieved Spitzer IRAC images of the same area and used archival Subaru Suprime-Cam and CFHT CFHT12K i-band images. Results: We report the detection of 9 new member candidates selected from optical and near-IR color-color and color-magnitude diagrams and 7 previously known members. The high spatial resolution images resolve 3 new visual multiple systems. Two of them are most likely not members of the association. The third one is made of a brown dwarf candidate companion to the F8V star HD 36861C. The simultaneous differential images allow us to rule out the presence of visual companions more massive than M>0.07 M⊙ in the range 1-2.5'', and M> 0.25 M⊙ in the range 0.5 arcsec - 2.5''. Based on observations made at the ESO La Silla and Paranal Observatory under programmes 082.C-0724, 080.D-0532(, 67.C-0042, 074.C-0084, and 074.C-0628, on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC) and at

  11. Status of known T type sources towards the σ Orionis cluster

    NASA Astrophysics Data System (ADS)

    Pena Ramirez, K.; Zapatero Osorio, M. R.; Bejar, V. J. S.

    2015-01-01

    We present the characterization of the three T type candidates (S Ori 70, S Ori 73, and S Ori J053804.65-021352.5) lying in the line of sight towards σ Orionis (˜3 Myr, ˜352 pc, solar metallicity) by means of near-infrared photometric, astrometric, and spectroscopic studies. H-band methane images were collected for all three sources using the LIRIS instrument on the 4.2 m William Herschel Telescope. J-band spectra of resolution ˜500 were obtained for S Ori J053804.65-021352.5 with the ISAAC spectrograph on the 8 m Very Large Telescope (VLT), and public low resolution (R˜50) JH spectra obtained with the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope (HST) were employed for the spectroscopic classification of S Ori 70 and 73. Accurate proper motions with a typical uncertainty of ±3 mas yr^{-1} were derived using ancient images and new data collected with ISAAC/VLT and WFC3/HST. The three objects were spectroscopically classified as T4.5 ± 0.5 (S Ori 73), T5 ± 0.5 (S Ori J053804.65-021352.5), and T7^{+0.5}_{-1.0} (S Ori 70). These spectral types agree with the H-band methane colors. The proper motions of S Ori 70 and 73 are larger than that of the cluster by >4 σ. The proper motion of S Ori J053804.65-021352.5 is consistent with a null displacement during the time interval of 7.03 yr.

  12. A SCUBA-2 850-μm survey of protoplanetary discs in the σ Orionis cluster

    NASA Astrophysics Data System (ADS)

    Williams, Jonathan P.; Cieza, Lucas A.; Andrews, Sean M.; Coulson, Iain M.; Barger, Amy J.; Casey, Caitlin M.; Chen, Chian-Chou; Cowie, Lennox L.; Koss, Michael; Lee, Nicholas; Sanders, David B.

    2013-10-01

    We present the results from a large 850-μm survey of the σ Orionis cluster using the SCUBA-2 camera on the James Clerk Maxwell Telescope. The 0.5° diameter circular region we surveyed contains 297 young stellar objects with an age estimated at about 3 Myr. We detect nine of these objects, eight of which have infrared excesses from an inner disc. We also serendipitously detect three non-stellar sources at >5σ that are likely background submillimetre galaxies. The nine detected stars have inferred disc masses ranging from 5 to about 17 MJup, assuming similar dust properties as Taurus discs and an interstellar medium gas-to-dust ratio of 100. There is a net positive signal towards the positions of the individually undetected infrared excess sources indicating a mean disc mass of 0.5 MJup. Stacking the emission towards those stars without infrared excesses constrains their mean disc mass to less than 0.3 MJup, or an equivalent Earth mass in dust. The submillimetre luminosity distribution is significantly different from that in the younger Taurus region, indicating disc mass evolution as star-forming regions age and the infrared excess fraction decreases. Submillimetre Array observations reveal CO emission towards four sources demonstrating that some, but probably not much, molecular gas remains in these relatively evolved discs. These observations provide new constraints on the dust and gas mass of protoplanetary discs during the giant planet building phase and provide a reference level for future studies of disc evolution.

  13. Five-Body Cluster Structure of the Double-{Lambda} Hypernucleus {sub {Lambda}{Lambda}}{sup 11}Be

    SciTech Connect

    Hiyama, E.; Kamimura, M.; Yamamoto, Y.; Motoba, T.

    2010-05-28

    Energy levels of the double {Lambda} hypernucleus, {sub {Lambda}{Lambda}}{sup 11}Be are calculated within the framework of a {alpha}{alpha}n{Lambda}{Lambda} five-body model. Interactions between constituent particles are determined so as to reproduce reasonably the observed low-energy properties of the {alpha}{alpha}, {alpha}{alpha}n nuclei and the existing data for {Lambda}-binding energies of the {alpha}{Lambda}, {alpha}{alpha}{Lambda}, {alpha}n{Lambda}, and {alpha}{alpha}n{Lambda} systems. An effective {Lambda}{Lambda} interaction is constructed so as to reproduce, within the {alpha}{Lambda}{Lambda} three-body model, the B{sub {Lambda}{Lambda}}of {sub {Lambda}{Lambda}}{sup 6}He, which was extracted from the emulsion experiment, the NAGARA event. With no adjustable parameters for the {alpha}{alpha}n{Lambda}{Lambda} system, B{sub {Lambda}{Lambda}}of the ground and bound excited states of {sub {Lambda}{Lambda}}{sup 11}Be are calculated with the Gaussian expansion method. The Hida event, recently observed at KEK-E373 experiment, is interpreted as an observation of the ground state of the {sub {Lambda}{Lambda}}{sup 11}Be.

  14. GAS CLUMPING IN THE OUTSKIRTS OF {Lambda}CDM CLUSTERS

    SciTech Connect

    Nagai, Daisuke; Lau, Erwin T.

    2011-04-10

    Recent Suzaku X-ray observations revealed that the observed entropy profile of the intracluster medium (ICM) deviates significantly from the prediction of hydrodynamical simulations of galaxy clusters. In this work, we show that gas clumping introduces significant biases in X-ray measurements of the ICM profiles in the outskirts of galaxy clusters. Using hydrodynamical simulations of galaxy cluster formation in a concordance {Lambda}CDM model, we demonstrate that gas clumping leads to an overestimate of the observed gas density and causes flattening of the entropy profile. Our results suggest that gas clumping must be taken into account when interpreting X-ray measurements of cluster outskirts.

  15. Are isolated planetary-mass objects really isolated?. A brown dwarf-exoplanet system candidate in the σ Orionis cluster

    NASA Astrophysics Data System (ADS)

    Caballero, J. A.; Martín, E. L.; Dobbie, P. D.; Barrado Y Navascués, D.

    2006-12-01

    Context: .Free-floating planetary-mass objects have masses below the deuterium burning mass limit at about 13 Jupiter masses, and have mostly been found in very young open clusters. Their origin and relationship to stars and brown dwarfs are still a mystery. Aims: .The recent detection by direct imaging of three giant planets at wide separation (50-250 AU) from their primaries has raised the question about the true "isolation" of planetary-mass objects in clusters. Our goal was to test the possibility that some free-floating planetary-mass objects could in fact be part of wide planetary systems. Methods: .We searched in the literature for stellar and brown-dwarf candidates members of the σ Orionis cluster (~3 Ma, ~360 pc) at small angular separations from published candidate planetary-mass objects. We found one candidate planetary system composed of an X-ray source, SE 70, and a planetary-mass object, S Ori 68, separated by only 4.6 arcsec. In order to assess the cluster membership of the X-ray source, we obtained mid-resolution optical spectroscopy using ISIS on the William Herschel Telescope. We also compiled additional data on the target from available astronomical catalogues. Results: .We have found that SE 70 follows the spectrophotometric sequence of the cluster and displays spectroscopic features of youth, such as lithium in absorption and chromospheric Hα emission. The radial velocity is consistent with cluster membership. Hence, SE 70 is very probably a member of the σ Orionis cluster. The projected physical separation between SE 70 and S Ori 68 is 1700~± 300 AU at the distance of the cluster. If a common proper motion is confirmed in the near future, the system would be composed of an M5-6 brown dwarf with an estimated mass of ~45 M_Jup and an L5 ± 2 giant planet with an estimated mass of ~5 M_Jup. It would be the widest and one of the lowest-mass planetary systems known so far.

  16. Beteigeuze (Alpha Orionis) und Mintaka (Delta Orionis)

    NASA Astrophysics Data System (ADS)

    Vollmann, Wolfgang

    2013-02-01

    Magnitude measures transformed to Johnson V of Alpha Orionis (Betelgeuse) and Delta Orionis with a wide-angle lens and DSLR are presented and discussed. Alpha Orionis light changes are shown clearly. The primary and secondary eclipses of Delta Orionis with amplitudes of 0.12 and 0.05 mag respectively are clearly recorded. They occur near phase 0.00 and 0.50 respectively of current elements from VSX (2).

  17. Excited states of {sub {lambda}}{sup 9}Be and {sub {lambda}}{sub {lambda}}{sup 10}Be in an {alpha} cluster model

    SciTech Connect

    Shoeb, Mohammad

    2006-12-15

    The energies of the degenerate spin-flip doublet (3{sup +}/2,5{sup +}/2) of {sub {lambda}}{sup 9}Be and of the 2{sup +} state of {sub {lambda}}{sub {lambda}}{sup 10}Be are analyzed in the {alpha} cluster model using a phenomenological dispersive three-body {lambda}{alpha}{alpha} force that reproduces the ground state energy of {sub {lambda}}{sup 9}Be. Two types of phenomenological {lambda}{alpha} and {alpha}{alpha} potentials and a few s-state {lambda}{lambda} potentials are taken as input. The energies of the excited states of the hypernuclei, treated as three- and four-body systems, calculated using the Variational Monte Carlo method, are in good agreement with the experimental values. Our results demonstrate that the existing data are insensitive to whether one employs a dispersive {lambda}{alpha}{alpha} force along with potentials in the relative angular momentum state l=0 and 2 as in the present work or whether one uses nonlocal {lambda}{alpha} potential as in earlier analyses.

  18. Membership, binarity and accretion among very low-mass stars and brown dwarfs of the σ Orionis cluster

    NASA Astrophysics Data System (ADS)

    Kenyon, M. J.; Jeffries, R. D.; Naylor, Tim; Oliveira, J. M.; Maxted, P. F. L.

    2005-01-01

    Intermediate-resolution (R~ 7000) spectroscopy is presented for 76 photometrically selected very low-mass (0.04 < M < 0.3 Msolar) candidate members of the young cluster around σ Orionis (σ Ori). More than two-thirds appear to be genuine cluster members on the basis that they exhibit LiI 6708-Åabsorption, weak NaI 8183/8195 Åfeatures and a radial velocity consistent with the cluster mean. Photometric selection alone therefore appears to be very effective in identifying cluster members in this mass range. Only six objects appear to be certain non-members; however, a substantial subset of 13 candidates have ambiguous or contradictory indications of membership and lack Li absorption. Together with an observed spread in the equivalent width of the Li absorption feature in the cooler stars of our sample, this indicates that there may be deficiencies in our understanding of the formation of this line in cool, low-gravity objects. Four candidate binary cluster members are identified. Consideration of sampling and radial velocity measurement precision leads us to conclude that either the fraction of very low-mass stars and brown dwarfs in small separation (a < 1 au) binary systems is larger than in field M-dwarfs, or the distribution of separations is much less skewed towards large separations. This conclusion hinges critically on the correct identification of the small number of binary candidates, although it remains significant even when only the candidate members displaying Li absorption are considered. Broadened Hα emission, indicative of circum(sub)stellar accretion discs is found in five or six of the candidate cluster members, three of which probably have substellar masses. The fraction of accretors (10 +/- 5 per cent) is similar to that found in stars of higher mass in the σ Ori cluster using Hα emission as a diagnostic, but much lower than found for very low-mass stars and brown dwarfs of younger clusters. The time-scale for accretion rates to drop to <~10

  19. BULLET CLUSTER: A CHALLENGE TO {Lambda}CDM COSMOLOGY

    SciTech Connect

    Lee, Jounghun; Komatsu, Eiichiro

    2010-07-20

    To quantify how rare the bullet-cluster-like high-velocity merging systems are in the standard {Lambda} cold dark matter (CDM) cosmology, we use a large-volume (27 h {sup -3} Gpc{sup 3}) cosmological N-body MICE simulation to calculate the distribution of infall velocities of subclusters around massive main clusters. The infall velocity distribution is given at (1-3)R{sub 200} of the main cluster (where R{sub 200} is similar to the virial radius), and thus it gives the distribution of realistic initial velocities of subclusters just before collision. These velocities can be compared with the initial velocities used by the non-cosmological hydrodynamical simulations of 1E0657-56 in the literature. The latest parameter search carried out by Mastropietro and Burkert has shown that an initial velocity of 3000 km s{sup -1} at about 2R{sub 200} is required to explain the observed shock velocity, X-ray brightness ratio of the main and subcluster, X-ray morphology of the main cluster, and displacement of the X-ray peaks from the mass peaks. We show that such a high infall velocity at 2R{sub 200} is incompatible with the prediction of a {Lambda}CDM model: the probability of finding 3000 km s{sup -1} in (2-3)R{sub 200} is between 3.3 x 10{sup -11} and 3.6 x 10{sup -9}. A lower velocity, 2000 km s{sup -1} at 2R{sub 200}, is also rare, and moreover, Mastropietro and Burkert have shown that such a low initial velocity does not reproduce the X-ray brightness ratio of the main and subcluster or morphology of the main cluster. Therefore, we conclude that the existence of 1E0657-56 is incompatible with the prediction of a {Lambda}CDM model, unless a lower infall velocity solution for 1E0657-56 with {approx}<1800 km s{sup -1} at 2R{sub 200} is found.

  20. YOUNG BROWN DWARFS AT HIGH CADENCE: WARM SPITZER TIME SERIES MONITORING OF VERY LOW MASS {sigma} ORIONIS CLUSTER MEMBERS

    SciTech Connect

    Cody, Ann Marie; Hillenbrand, Lynne A.

    2011-11-01

    The continuous temporal coverage and high photometric precision afforded by space observatories have opened up new opportunities for the study of variability processes in young stellar cluster members. Of particular interest is the phenomenon of deuterium-burning pulsation in brown dwarfs (BDs) and very low mass stars, whose existence on 1-4 hr timescales has been proposed but not yet borne out by observations. To investigate short-timescale variability in young, low-mass objects, we carried out high-precision, high-cadence time series monitoring with the Warm Spitzer mission on 14 low mass stars and BDs in the {approx}3 Myr {sigma} Orionis cluster. The flux in many of our raw light curves is strongly correlated with subpixel position and can vary systematically by as much as 10%. We present a new approach to disentangle true stellar variability from this 'pixel-phase effect', which is more pronounced in Warm Spitzer observations as compared to the cryogenic mission. The light curves after correction reveal that most of the sample is devoid of variability down to the few-millimagnitude (mmag) level, on the minute to day timescales probed. However, one exceptional BD displays erratic brightness changes at the 10%-15% level, suggestive of variable obscuration by dusty material. The uninterrupted 24 hr datastream and sub-1% photometric precision enable limits on pulsation in the near-infrared. If this phenomenon is present in our light curves, then its amplitude must lie below 2-3 mmag. In addition, we present three field eclipsing binaries and one pulsator for which optical ground-based data are also available.

  1. Comparison of Cluster Lensing Profiles with Lambda CDM Predictions

    SciTech Connect

    Broadhurst, Tom; Umetsu, Keiichi; Medezinski, Elinor; Oguri, Masamune; Rephaeli, Yoel; /Tel Aviv U. /San Diego, CASS

    2008-05-21

    We derive lens distortion and magnification profiles of four well known clusters observed with Subaru. Each cluster is very well fitted by the general form predicted for Cold Dark Matter (CDM) dominated halos, with good consistency found between the independent distortion and magnification measurements. The inferred level of mass concentration is surprisingly high, 8 < c{sub vir} < 15 ( = 10.39 {+-} 0.91), compared to the relatively shallow profiles predicted by the {Lambda}CDM model, c{sub vir} = 5.06 {+-} 1.10 (for = 1.25 x 10{sup 15} M{sub {circle_dot}}/h). This represents a 4{sigma} discrepancy, and includes the relatively modest effects of projection bias and profile evolution derived from N-body simulations, which oppose each other with little residual effect. In the context of CDM based cosmologies, this discrepancy implies some modification of the widely assumed spectrum of initial density perturbations, so clusters collapse earlier (z {ge} 1) than predicted (z < 0.5) when the Universe was correspondingly denser.

  2. Shell and cluster states of {sub {Lambda}}{sup 21}Ne studied with antisymmetrized molecular dynamics

    SciTech Connect

    Isaka, Masahiro; Kimura, Masaaki; Dote, Akinobu; Ohnishi, Akira

    2011-05-15

    The low-lying states of {sub {Lambda}}{sup 21}Ne are studied with antisymmetrized molecular dynamics for hypernuclei. We have obtained ten rotational bands where the number of bands are increased compared to {sup 20}Ne by adding a {Lambda} hyperon. Among them, we focus on the K{sup {pi}=}0{sub 1}{sup +} x {Lambda}{sub s} and K{sup {pi}=}0{sub 1}{sup -} x {Lambda}{sub s} bands. The former has a shell-model-like structure that has {Lambda} in an s wave coupled to the ground band of {sup 20}Ne. The latter is a cluster state that has a {alpha}+{sub {Lambda}}{sup 17}O dicluster structure. The difference between their structures leads to the binding energy of {Lambda} particle B{sub {Lambda}} and reduction of the E2 transition probabilities B(E2).

  3. lambda lambda. hypernuclei and the. lambda lambda. interaction

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.

    1986-01-01

    Variational calculations of ..cap alpha..-cluster models for /sup 6//sub ..lambda lambda../He, /sup 9//sub ..lambda lambda../Be have been made. These calculations require a knowledge of the ..cap alpha lambda.. potential which is obtained in several ways including the use of five-body Monte Carlo (MC) calculations of /sup 5//sub ..lambda../He. We discuss the ..lambda lambda.. interaction strengths and the relation between the /sup 6//sub ..lambda lambda../He and /sup 10//sub ..lambda lambda../Be binding energies and, in particular, the dependence of these on the ..cap alpha lambda.. potential. For all our ..cap alpha lambda.. potentials the binding energy of /sup 6//sub ..lambda lambda../He predicted from /sup 10//sub ..lambda lambda../Be is 1 MeV or more below the experimental value. A brief discussion is given of the implication of the phenomenological strength of ..lambda lambda.. interaction we obtain and also the implication of ..lambda lambda.. hypernuclei for the H-dibaryon. 19 refs., 2 figs., 1 tab.

  4. Structure of A=7 iso-triplet {lambda} hypernuclei studied with the four-body cluster model

    SciTech Connect

    Hiyama, E.; Yamamoto, Y.; Motoba, T.; Kamimura, M.

    2009-11-15

    The structure of the T=1 isotriplet hypernuclei, {sub {lambda}}{sup 7}He, {sub {lambda}}{sup 7}Li, and {sub {lambda}}{sup 7}Be within the framework of an {alpha}+{lambda}+N+N four-body cluster model is studied. Interactions between the constituent subunits are determined so as to reproduce reasonably well the observed low-energy properties of the {alpha}N, {alpha}{lambda}, {alpha}NN, and {alpha}{lambda}N subsystems. Furthermore, the two-body {lambda}N interaction is adjusted so as to reproduce the 0{sup +}-1{sup +} splitting of {sub {lambda}}{sup 4}H. Also, a phenomenological {lambda}N charge symmetry breaking (CSB) interaction is introduced. The {lambda} binding energy of the ground state in {sub {lambda}}{sup 7}He is predicted to be 5.16(5.36) MeV with (without) the CSB interaction. The calculated energy splittings of the 3/2{sup +}-5/2{sup +} states in {sub {lambda}}{sup 7}He and {sub {lambda}}{sup 7}Li are around 0.1 MeV. We point out that there is a three-layer structure of the matter distribution, {alpha} particle, {lambda} skin, and proton or neutron halo, in the {sub {lambda}}{sup 7}He(J=5/2{sup +}), {sub {lambda}}{sup 7}Li(J=5/2{sup +}), and {sub {lambda}}{sup 7}Be(J=1/2{sup +}) states.

  5. Container structure of alpha-alpha-Lambda clusters in 9-Lambda-Beryrium

    NASA Astrophysics Data System (ADS)

    Funaki, Yasuro; Yamada, Taiichi; Hiyama, Emiko; Zhou, Bo; Ikeda, Kiyomi

    2014-11-01

    A new concept of clustering is discussed in Λ hypernuclei using a new-type microscopic cluster model wave function, which has a structure in which constituent clusters are confined in a container, whose size is a variational parameter and which we refer to as a hyper-Tohsaki-Horiuchi-Schuck-Röpke (hyper-THSR) wave function. By using the hyper-THSR wave function, the 2α + Λ-cluster structure in {{^9_Λ}{Be}} is investigated. We show that full microscopic solutions in the 2α + Λ-cluster system, which are given as 2α + Λ Brink-GCM (generator coordinate method) wave functions, are almost perfectly reproduced by the single configurations of the hyper-THSR wave function. The squared overlaps between both wave functions are calculated to be 99.5%, 99.4%, and 97.7% for J^π =0^+ , 2^+ , and 4^+ states, respectively. We also simulate the structural change by adding the Λ particle, by varying the Λ N interaction artificially. With the increase of the Λ N interaction, the Λ particle gets to move more deeply inside the core and strongly invokes the spatial core shrinkage. Accordingly, distinct localized 2α clusters appear in the nucleonic intrinsic density, though, in the {^8Be} nucleus, a gaslike 2α-cluster structure is shown. The origin of the localization is associated with the strong effect of the Pauli principle. We conclude that the container picture of the 2α and Λ clusters is essential in understanding the cluster structure in {^9_ΛBe}, in which the very compact spatial localization of clusters is shown in the density distribution.

  6. An {alpha}-cluster model for {sub {Lambda}}{sup 9}Be spectroscopy

    SciTech Connect

    Filikhin, I. N. Suslov, V. M.; Vlahovic, B.

    2013-03-15

    An {alpha}-cluster model is applied to study low-lying spectrum of the {sub {Lambda}}{sup 9}Be hypernucleus. The three-body {alpha}{alpha}{Lambda} problem is numerically solved by the Faddeev equations in configuration space using phenomenological pair potentials. We found a set of the potentials that reproduces experimental data for the ground state (1/2{sup +}) binding energy and excitation energy of the 5/2{sup +} and 3/2{sup +} states, simultaneously. This set includes the Ali-Bodmer potential of the version 'e' for {alpha}{alpha} and modified Tang-Herndon potential for {alpha}{Lambda} interactions. The spin-orbit {alpha}{Lambda} interaction is given by modified Scheerbaum potential. Low-lying energy levels are evaluated applying a variant of the analytical continuation method in the coupling constant. It is shown that the spectral properties of {sub {Lambda}}{sup 9}Be can be classified as an analog of {sup 9}Be spectrum with the exception of several 'genuine hypernuclear states'. This agrees qualitatively with previous studies. The results are compared with experimental data and new interpretation of the spectral structure is discussed.

  7. Lithium and Hα in stars and brown dwarfs of sigma Orionis.

    NASA Astrophysics Data System (ADS)

    Zapatero Osorio, M. R.; Béjar, V. J. S.; Pavlenko, Ya.; Rebolo, R.; Allende Prieto, C.; Martín, E. L.; García López, R. J.

    2002-03-01

    We present intermediate- and low-resolution optical spectra around Hα and Li I lambda 6708 Åfor a sample of 25 low mass stars and 2 brown dwarfs with confirmed membership in the pre-main sequence stellar sigma Orionis cluster. Our observations are intended to investigate the age of the cluster. The spectral types derived for our target sample are found to be in the range K6-M8.5, which corresponds to a mass interval of roughly 1.2-0.02 Msun on the basis of state-of-the-art evolutionary models. Radial velocities (except for one object) are found to be consistent with membership in the Orion complex. All cluster members show considerable Hα emission and the Li I resonance doublet in absorption, which is typical of very young ages. We find that our pseudo-equivalent widths of Hα and Li I (measured relative to the observed local pseudo-continuum formed by molecular absorptions) appear rather dispersed (and intense in the case of Hα ) for objects cooler than M3.5 spectral class, occurring at the approximate mass where low mass stars are expected to become fully convective. The least massive brown dwarf in our sample, S Ori 45 (M8.5, ~ 0.02 Msun), displays variable Hα emission and a radial velocity that differs from the cluster mean velocity. Tentative detection of forbidden lines in emission indicates that this brown dwarf may be accreting mass from a surrounding disk. We also present recent computations of Li I lambda 6708 Åcurves of growth for low gravities and for the temperature interval (about 4000-2600 K) of our sample. The comparison of our observations to these computations allows us to infer that no lithium depletion has yet taken place in sigma Orionis, and that the observed pseudo-equivalent widths are consistent with a cluster initial lithium abundance close to the cosmic value. Hence, the upper limit to the sigma Orionis cluster age can be set at 8 Myr, with a most likely value around 2-4 Myr. Based on observations made with the following telescopes

  8. Low-lying spectra of {sup 9}{Lambda}Be and {sup 9}Be within three-cluster model

    SciTech Connect

    Filikhin, I.; Suslov, V. M.; Vlahovic, B.

    2011-10-24

    An {alpha}-cluster model is applied to study the low-lying spectra of the {sup 9}{Lambda}Be and {sup 9}Be nuclei. The {alpha}{alpha}{Lambda} and {alpha}{alpha}n three-body problems are numerically solved by the Faddeev equations in configuration space using phenomenological pair potentials with spin-orbital {alpha}{Lambda} and {alpha}n interactions taken into account. For the {sup 9}{Lambda}Be hypernucleus we found a set of the potentials that reproduces the experimental data for the ground state (1/2 {sup +}) binding energy and excitation energy of the 5/2{sup +} and 3/2 {sup +} states, simultaneously. The LS coupling scheme is used for partial wave analysis. The total orbital momentum is fixed for each energy level. Under this assumption we calculated the {sup 9}Be spectrum within {alpha}{alpha}n model. The experiential data are well reproduced by the model, when a new classification for low-lying levels of {sup 9}Be as members of spin-flip doublets is applied.

  9. Existence of {sub {lambda}}{sub {lambda}}{sup 4}H: A variational Monte Carlo search

    SciTech Connect

    Shoeb, Mohammad

    2005-02-01

    A variational Monte Carlo (VMC) calculation for the binding energy B{sub {lambda}}{sub {lambda}} of the lightest hypernucleus {sub {lambda}}{sub {lambda}}{sup 4}H has been performed in the four-body {lambda}{lambda}pn model. A range of input {lambda}{lambda} potentials of moderate strength produce a particle-stable {sub {lambda}}{sub {lambda}}{sup 4}H for the simulated NSC97e and f {lambda}N potentials, whereas the phenomenological Minnesota {lambda}N potential needs a much stronger {lambda}{lambda} potential to bind. The VMC results for B{sub {lambda}}{sub {lambda}} agree with the prediction of the stochastic variational model but contradict the recent Faddeev-Yakubovsky calculation. As reported earlier, B{sub {lambda}}{sub {lambda}} is sensitive to the triplet {lambda}N channel for a given {lambda}{lambda} potential. The B{sub {lambda}}{sub {lambda}} of {sub {lambda}}{sub {lambda}}{sup 4}H in the three-body {lambda}{lambda}d cluster model is consistent with but slightly lower than the Faddeev calculation. The VMC method predicts a stable {sub {lambda}}{sub {lambda}}{sup 4}H system in both models and thus offers the possibility of identifying {sub {lambda}}{sub {lambda}}{sup 4}H in a future extension of E906 or of a related experiment at KEK, provided the simulated potentials are true representations of realistic Nijmegen potentials.

  10. Protoplanetary Formation and the FU Orionis Outburst

    NASA Technical Reports Server (NTRS)

    Bodenheimer, P. H.

    1996-01-01

    The following three publications which reference the above grant from the NASA Origins of Solar Systems program are attached and form the final technical report for this project. The research involved comparisons of the spectral energy distributions of FU Orionis objects with theoretical models and associated studies of the structure of the outbursting accretion disks, as well as related studies on the effects of magnetic fields in disks, which will lead in the future to models of FU Orionis outbursts which include the effects of magnetic fields. The project was renewed under a new grant NAGW-4456, entitled 'Effects of FU Orionis Outbursts on Protoplanetary Disks'. Work now being prepared for publication deals more specifically with the issue of the effects of the outbursts on protoplanetary formation. Models of the spectral energy distribution of FU Orionis stars. A simple model of a buoyant magnetic dynamo in accretion disks and a numerical study of magnetic buoyancy in an accretion disk have been submitted.

  11. S Orionis 70: Just a Foreground Field Brown Dwarf?

    NASA Astrophysics Data System (ADS)

    Burgasser, Adam J.; Kirkpatrick, J. Davy; McGovern, Mark R.; McLean, Ian S.; Prato, L.; Reid, I. Neill

    2004-04-01

    We examine recent claims that the T-type brown dwarf S Ori 053810.1-203626 (S Ori 70) is a spectroscopically verified low-mass (3+5-1 MJup) member of the 1-8 Myr σ Orionis cluster. Comparative arguments by Martín & Zapatero Osorio asserting that S Ori 70 exhibits low surface gravity spectral features indicative of youth and low mass are invalidated by the fact that their comparison object was not the field T dwarf 2MASS 0559-1404, but rather a nearby background star. Instead, we find that the 1-2.5 μm spectra of S Ori 70 are well matched to older (age~few Gyr) field T6-T7 dwarfs. Moreover, we find that spectral model fits to late-type field T dwarf spectra tend to yield low surface gravities (logg=3.0-3.5), and thus young ages (<~5 Myr) and low masses (<~3 MJup), inconsistent with expected and/or empirical values. Finally, we show that the identification of one T dwarf in the field imaged by Zapatero Osorio et al. is statistically consistent with the expected foreground contamination. Based on the reexamined evidence, we conclude that S Ori 70 may simply be an old, massive (30-60 MJup) field brown dwarf lying in the foreground of the σ Orionis cluster. This interpretation should be considered before presuming the existence of so-called ``cluster planets.''

  12. X-ray clusters in a cold dark matter + lambda universe: A direct, large-scale, high-resolution, hydrodynamic simulation

    NASA Technical Reports Server (NTRS)

    Cen, Renyue; Ostriker, Jeremiah P.

    1994-01-01

    A new, three-dimensional, shock-capturing, hydrodynamic code is utilized to determine the distribution of hot gas in a cold dark matter (CDM) + lambda model universe. Periodic boundary conditions are assumed: a box with size 85/h Mpc, having cell size 0.31/h Mpc, is followed in a simulation with 270(exp 3) = 10(exp 7.3) cells. We adopt omega = 0.45, lambda = 0.55, h identically equal to H/100 km/s/Mpc = 0.6, and then, from the cosmic background explorer (COBE) and light element nucleosynthesis, sigma(sub 8) = 0.77, omega(sub b) = 0.043. We identify the X-ray emitting clusters in the simulation box, compute the luminosity function at several wavelength bands, the temperature function and estimated sizes, as well as the evolution of these quantities with redshift. This open model succeeds in matching local observations of clusters in contrast to the standard omega = 1, CDM model, which fails. It predicts an order of magnitude decline in the number density of bright (h nu = 2-10 keV) clusters from z = 0 to z = 2 in contrast to a slight increase in the number density for standard omega = 1, CDM model. This COBE-normalized CDM + lambda model produces approximately the same number of X-ray clusters having L(sub x) greater than 10(exp 43) erg/s as observed. The background radiation field at 1 keV due to clusters is approximately the observed background which, after correction for numerical effects, again indicates that the model is consistent with observations.

  13. FU Orionis Outbursts and the Solar Nebula

    NASA Technical Reports Server (NTRS)

    Bell, Robbins; Young, Rich (Technical Monitor)

    1998-01-01

    Protostellar systems are variable on many timescales. The FU Orionis outburst is one of the most drastic forms of variability known to occur in low mass stellar systems. During a typical outburst lasting several decades, system luminosities may be a hundred times what is normal of the quiescent state. FU Orionis outburst events are believed to have significant impacts on the thermal structure of the protosolar nebula. Their existence has been utilized to explain features in the meteoritic record from thermally induced homogenization to chondrule formation. Recent numerical models have shown the viability of the hypothesis that the radiation observed during outburst is emitted by a luminous circumstellar disk transporting mass at a thousand times the quiescent rate. We will begin by describing what is known about the FU Orionis outburst phenomenon from recent observations and theory. We will discuss evidence that suggests that outburst radiation is emitted by a circumstellar disk rather than by the star and will briefly describe the thermal instability as a mechanism for outburst. Additional information is contained in the original extended abstract.

  14. Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

    SciTech Connect

    Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman

    2014-05-21

    Water–tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with x{sub TBA} ≈ 0.03–0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at x{sub TBA} ≈ 0.05. We note that “islands” of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, x{sub TBA} ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level.

  15. Fluctuating micro-heterogeneity in water-tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies.

    PubMed

    Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman

    2014-05-21

    Water-tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with x(TBA) ≈ 0.03-0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at x(TBA) ≈ 0.05. We note that "islands" of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, x(TBA) ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level. PMID:24852545

  16. Spitzer IRS Observations of FU Orionis Objects

    NASA Astrophysics Data System (ADS)

    Green, J. D.; Hartmann, L.; Calvet, N.; Watson, D. M.; Ibrahimov, M.; Furlan, E.; Sargent, B.; Forrest, W. J.

    2006-09-01

    We present 5-35 μm spectra, taken with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope, of five FU Orionis objects: FU Ori, V1515 Cyg, V1057 Cyg, BBW 76, and V346 Nor. All but V346 Nor reveal amorphous silicate grains in emission at 10 and 20 μm, and show water-vapor absorption bands at 5.8 and 6.8 μm and SiO or possibly methane absorption at 8 μm. These absorption features closely match these bands in model stellar photospheres-signs of the gaseous photospheres of the inner regions of these objects' accretion disks. The continuum emission at 5-8 μm is also consistent with such disks, and, for FU Orionis and BBW 76, longer wavelength emission may be fit by a model that includes moderate disk flaring. V1057 Cyg and V1515 Cyg have much more emission at longer wavelengths than the others, perhaps evidence of a substantial remnant of their natal, infalling envelopes.

  17. The Evolution of FU Orionis Disks

    NASA Astrophysics Data System (ADS)

    Green, Joel D.

    2016-06-01

    Do protoplanetary disks undergo regular (or irregular) bursts of accretion? FU Orionis objects (FUors) are the strongest direct evidence for episodic accretion in low mass young stellar objects. FUors exhibit rapid changes in disk chemistry, both because they are temporarily bright IR sources relative to their core mass, and vary on day, month, year, and decade timescales. With improved spatial and spectral resolution from FORCAST, and a ten year time baseline compared with Spitzer-IRS data, we can observe and constrain the properties of silicate dust, and disk profiles, as they are altered by the outburst. We also consider the occurrence of binarity and whether any connection exists between multiplicity and evidence of recent outburst behavior.

  18. MULTIWAVELENGTH OBSERVATIONS OF V2775 Ori, AN OUTBURSTING PROTOSTAR IN L 1641: EXPLORING THE EDGE OF THE FU ORIONIS REGIME

    SciTech Connect

    Fischer, William J.; Megeath, S. Thomas; Kounkel, Marina; Tobin, John J.; Stutz, Amelia M.; Henning, Thomas; Ali, Babar; Stanke, Thomas; Osorio, Mayra; Wilson, T. L.

    2012-09-01

    Individual outbursting young stars are important laboratories for studying the physics of episodic accretion and the extent to which this phenomenon can explain the luminosity distribution of protostars. We present new and archival data for V2775 Ori (HOPS 223), a protostar in the L 1641 region of the Orion molecular clouds that was discovered by Caratti o Garatti et al. to have recently undergone an order-of-magnitude increase in luminosity. Our near-infrared spectra of the source have strong blueshifted He I {lambda}10830 absorption, strong H{sub 2}O and CO absorption, and no H I emission, all typical of FU Orionis sources. With data from the Infrared Telescope Facility, the Two Micron All Sky Survey, the Hubble Space Telescope, Spitzer, the Wide-field Infrared Survey Explorer, Herschel, and the Atacama Pathfinder Experiment that span from 1 to 70 {mu}m pre-outburst and from 1 to 870 {mu}m post-outburst, we estimate that the outburst began between 2005 April and 2007 March. We also model the pre- and post-outburst spectral energy distributions of the source, finding it to be in the late stages of accreting its envelope with a disk-to-star accretion rate that increased from {approx}2 Multiplication-Sign 10{sup -6} M{sub Sun} yr{sup -1} to {approx}10{sup -5} M{sub Sun} yr{sup -1} during the outburst. The post-outburst luminosity at the epoch of the FU Orionis-like near-IR spectra is 28 L{sub Sun }, making V2775 Ori the least luminous documented FU Orionis outburster with a protostellar envelope. The existence of low-luminosity outbursts supports the notion that a range of episiodic accretion phenomena can partially explain the observed spread in protostellar luminosities.

  19. Spectroscopic Assessment of WISE-based Young Stellar Object Selection Near λ and σ Orionis

    NASA Astrophysics Data System (ADS)

    Koenig, Xavier; Hillenbrand, Lynne A.; Padgett, Deborah L.; DeFelippis, Daniel

    2015-10-01

    We have conducted a sensitive search down to the hydrogen burning limit for unextincted stars over ∼200 square degrees around Lambda Orionis and 20 square degrees around Sigma Orionis using the methodology of Koenig & Leisawitz. From WISE and 2MASS data we identify 544 and 418 candidate young stellar objects (YSOs) in the vicinity of λ and σ respectively. Based on our followup spectroscopy for some candidates and the existing literature for others, we found that ∼80% of the K14-selected candidates are probable or likely members of the Orion star-forming region. The yield from the photometric selection criteria shows that WISE sources with {K}S-w3\\gt 1.5 mag and KS between 10 and 12 mag are most likely to show spectroscopic signs of youth, while WISE sources with {K}S-w3 > 4 mag and {K}S\\gt 12 were often active galactic nuclei when followed up spectroscopically. The population of candidate YSOs traces known areas of active star formation, with a few new “hot spots” of activity near Lynds 1588 and 1589 and a more dispersed population of YSOs in the northern half of the H ii region bubble around σ and ɛ Ori. A minimal spanning tree analysis of the two regions to identify stellar groupings finds that roughly two-thirds of the YSO candidates in each region belong to groups of 5 or more members. The population of stars selected by WISE outside the MST groupings also contains spectroscopically verified YSOs, with a local stellar density as low as 0.5 stars per square degree.

  20. X-RAY VARIABILITY OF {sigma} ORIONIS YOUNG STARS AS OBSERVED WITH ROSAT

    SciTech Connect

    Caballero, J. A.; Lopez-Santiago, J.; De Castro, E.; Cornide, M.

    2009-06-15

    We used the Aladin Virtual Observatory tool and High Resolution Imager ROSAT archival data to search for X-ray variability in scale of days in 23 young stars in the {sigma} Orionis cluster and a background galaxy. Five stars displayed unambiguous flares and had probabilities p {sub var}>> 99% of being actual variables. Two of the detected flares were violent and long lasting, with maximum duration of six days and amplitude of eight times above the quiescent level. We classified another four stars as possible X-ray variables, including the binary system formed by the B2Vp star {sigma} Ori E and its close late-type companion. This makes a minimum frequency of high-amplitude X-ray variability in excess of a day of 39% among {sigma} Orionis stars. The incidence of this kind of X-ray variability seems to be lower among classical T Tauri stars with mid-infrared flux excesses than among fast-rotating, disk-less young stars.

  1. Binding energy of (Lambda)He-7 and test of charge symmetry breaking in the Lambda N interaction potential

    SciTech Connect

    Hashimoto, O; Honda, D; Kaneta, M; Kato, F; Kawama, D; Maruyama, N; Matsumura, A; Nakamura, S N; Nomura, H; Nonaka, K; Ohtani, A; Okayasu, Y; Osaka, M; Oyamada, M; Sumihama, M; Tamura, H; Baker, O K; Cole, L; Christy, M; Gueye, P; Keppel, C; Tang, L; Yuan, L; Acha, A; Baturin, P; Boeglin, W; Kramer, L; Markowitz, P; Pamela, P; Perez, N; Raue, B; Reinhold, J; Rivera, R; Kato, S; Sato, Y; Takahashi, T; Daniel, A; Hungerford, Ed V; Ispiryan, M; Kalantarians, N; Lan, K J; Li, Y; Miyoshi, T; Randeniya, S; Rodriguez, V M; Bosted, P; Carlini, R; Ent, R; Fenker, H; Gaskell, D; Jones, M; Mack, D; Roche, J; Smith, G; Tvaskis, V; Vulcan, W; Wood, S; Yan, C; Asaturyan, A; Asaturyan, R; Egiyan, K; Mkrtchyan, H; Margaryan, A; Navasardyan, T; Tadevosyan, V; Zamkochian, S; Hu, B; Song, Y; Luo, W; Androic, D; Furic, M; Petkovic, T; Seva, T; Ahmidouch, A; Danagoulian, S; Gasparian, A; Halkyard, R; Johnson, K; Simicevic, N; Wells, S; Niculescu, G; Niculescu, M I; Gan, L; Benmokhtar, F; Horn, T; Elassar, M; Gibson, E F

    2011-09-01

    The binding energy of 7LambdaHe has been obtained for the first time with reaction spectroscopy using the (e, e'K+) reaction at Jefferson Lab's Hall C. A comparison among the binding energies of the A = 7 T = l iso-triplet hypernuclei, 7LambdaHe, 7LambdaLi*and 7LambdaBe, is made and possible charge symmetry breaking (CSB) in the LambdaN potential is discussed. For 7LambdaHe and 7LambdaBe, the shifts in binding energies are opposite to those predicted by a recent cluster model calculation, which assumes that the unexplained part of the binding energy difference between 4LambdaH and 4LambdaHe, is due to the CSB of the LambdaN potential. Further examination of CSB in light hypernuclear systems is required both experimentally and theoretically.

  2. FU Orionis: The MIDI VLTI Perspective

    NASA Astrophysics Data System (ADS)

    Quanz, S. P.; Henning, Th.; Bouwman, J.; Ratzka, Th.; Leinert, Ch.

    2006-09-01

    We present the first mid-infrared interferometric measurements of FU Orionis. We clearly resolve structures that are best explained with an optically thick accretion disk. A simple accretion disk model fits the observed SED and visibilities reasonably well and does not require the presence of any additional structure such as a dusty envelope. The inclination and also the position angle of the disk can be constrained from the multibaseline interferometric observations. Our disk model is in general agreement with most published near-infrared interferometric measurements. From the shape and strength of the 8-13 μm spectrum, the dust composition of the accretion disk is derived for the first time. We conclude that most dust particles are amorphous and already much larger than those typically observed in the ISM. Although the high accretion rate of the system provides both high temperatures out to large radii and an effective transport mechanism to distribute crystalline grains, we do not see any evidence for crystalline silicates in either the total spectrum or the correlated flux spectra from the inner disk regions. Possible reasons for this nondetection are mentioned. All results are discussed in context with other high spatial resolution observations of FU Ori and other FU Ori objects. We also address the question whether FU Ori is in a younger evolutionary stage than a classical T Tauri star. Based on observations made with ESO Telescopes at the Paranal Observatories under program ID 074.C-0209 and 274.C-5032.

  3. Keck Interferometer Observations of FU Orionis Objects

    NASA Astrophysics Data System (ADS)

    Millan-Gabet, R.; Monnier, J. D.; Akeson, R. L.; Hartmann, L.; Berger, J.-P.; Tannirkulam, A.; Melnikov, S.; Billmeier, R.; Calvet, N.; D'Alessio, P.; Hillenbrand, L. A.; Kuchner, M.; Traub, W. A.; Tuthill, P. G.; Beichman, C.; Boden, A.; Booth, A.; Colavita, M.; Creech-Eakman, M.; Gathright, J.; Hrynevych, M.; Koresko, C.; Le Mignant, D.; Ligon, R.; Mennesson, B.; Neyman, C.; Sargent, A.; Shao, M.; Swain, M.; Thompson, R.; Unwin, S.; van Belle, G.; Vasisht, G.; Wizinowich, P.

    2006-04-01

    We present new K-band long-baseline interferometer observations of three young stellar objects of the FU Orionis class, namely, V1057 Cyg, V1515 Cyg, and Z CMa-SE, obtained at the Keck Interferometer during its commissioning science period. The interferometer clearly resolves the source of near-infrared emission in all three objects. Using simple geometric models, we derive size scales (0.5-4.5 AU) for this emission. All three objects appear significantly more resolved than expected from simple models of accretion disks tuned to fit the broadband optical and infrared spectrophotometry. We explore variations in the key parameters that are able to lower the predicted visibility amplitudes to the measured levels and conclude that accretion disks alone do not reproduce the spectral energy distributions and K-band visibilities simultaneously. We conclude that either disk models are inadequate to describe the near-infrared emission or additional source components are needed. We hypothesize that large-scale emission (tens of AU) in the interferometer field of view is responsible for the surprisingly low visibilities. This emission may arise in scattering by large envelopes believed to surround these objects.

  4. Lambda Vision

    NASA Astrophysics Data System (ADS)

    Czajkowski, Michael

    2014-06-01

    There is an explosion in the quantity and quality of IMINT data being captured in Intelligence Surveillance and Reconnaissance (ISR) today. While automated exploitation techniques involving computer vision are arriving, only a few architectures can manage both the storage and bandwidth of large volumes of IMINT data and also present results to analysts quickly. Lockheed Martin Advanced Technology Laboratories (ATL) has been actively researching in the area of applying Big Data cloud computing techniques to computer vision applications. This paper presents the results of this work in adopting a Lambda Architecture to process and disseminate IMINT data using computer vision algorithms. The approach embodies an end-to-end solution by processing IMINT data from sensors to serving information products quickly to analysts, independent of the size of the data. The solution lies in dividing up the architecture into a speed layer for low-latent processing and a batch layer for higher quality answers at the expense of time, but in a robust and fault-tolerant way. This approach was evaluated using a large corpus of IMINT data collected by a C-130 Shadow Harvest sensor over Afghanistan from 2010 through 2012. The evaluation data corpus included full motion video from both narrow and wide area field-of-views. The evaluation was done on a scaled-out cloud infrastructure that is similar in composition to those found in the Intelligence Community. The paper shows experimental results to prove the scalability of the architecture and precision of its results using a computer vision algorithm designed to identify man-made objects in sparse data terrain.

  5. Shell-model predictions for Lambda Lambda hypernuclei

    SciTech Connect

    Gal, A.; Millener, D.

    2011-06-02

    It is shown how the recent shell-model determination of {Lambda}N spin-dependent interaction terms in {Lambda} hypernuclei allows for a reliable deduction of {Lambda}{Lambda} separation energies in {Lambda}{Lambda} hypernuclei across the nuclear p shell. Comparison is made with the available data, highlighting {sub {Lambda}{Lambda}}{sup 11}Be and {sub {Lambda}{Lambda}}{sup 12}Be which have been suggested as possible candidates for the KEK-E373 HIDA event.

  6. Study of {Lambda}-{Lambda} oscillation in quantum coherent {Lambda}{Lambda} by using J/{psi}{yields}{Lambda}{Lambda} decay

    SciTech Connect

    Kang Xianwei; Li Haibo; Lu Gongru

    2010-03-01

    We discuss the possibility of searching for the {Lambda}-{Lambda} oscillations for coherent {Lambda}{Lambda} production in the J/{psi}{yields}{Lambda}{Lambda} decay process. The sensitivity of measurement of {Lambda}-{Lambda} oscillation in the external field at BES-III experiment is considered. These considerations indicate an alternative way to probe the {Delta}B=2 amplitude in addition to neutron oscillation experiments. Both coherent and time-dependent information can be used to extract the {Lambda}-{Lambda} oscillation parameter. With one year's luminosity at BES-III, we can set an upper limit of {delta}m{sub {Lambda}{Lambda}<}10{sup -15} MeV at 90% confidence level, corresponding to about 10{sup -6} s of {Lambda}-{Lambda} oscillation time.

  7. VARIABILITY IN OPTICAL SPECTRA OF {epsilon} ORIONIS

    SciTech Connect

    Thompson, Gregory B.; Morrison, Nancy D. E-mail: nmorris@utnet.utoledo.edu

    2013-04-15

    We present the results of a time series analysis of 130 echelle spectra of {epsilon} Ori (B0 Ia), acquired over seven observing seasons between 1998 and 2006 at Ritter Observatory. The equivalent widths of H{alpha} (net) and He I {lambda}5876 were measured and radial velocities were obtained from the central absorption of He I {lambda}5876. Temporal variance spectra (TVS) revealed significant wind variability in both H{alpha} and He I {lambda}5876. The He I TVS have a double-peaked profile consistent with radial velocity oscillations. A periodicity search was carried out on the equivalent width and radial velocity data, as well as on wavelength-binned spectra. This analysis has revealed several periods in the variability with timescales of two to seven days. Many of these periods exhibit sinusoidal modulation in the associated phase diagrams. Several of these periods were present in both H{alpha} and He I, indicating a possible connection between the wind and the photosphere. Due to the harmonic nature of these periods, stellar pulsations may be the origin of some of the observed variability. Periods on the order of the rotational period were also detected in the He I line in the 1998-1999 season and in both lines during the 2004-2005 season. These periods may indicate rotational modulation due to structure in the wind.

  8. The low-mass star and sub-stellar populations of the 25 Orionis group

    NASA Astrophysics Data System (ADS)

    Downes, Juan José; Briceño, César; Mateu, Cecilia; Hernández, Jesús; Vivas, Anna Katherina; Calvet, Nuria; Hartmann, Lee; Petr-Gotzens, Monika G.; Allen, Lori

    2014-10-01

    We present the results of a survey of the low-mass star and brown dwarf population of the 25 Orionis group. Using optical photometry from the CIDA (Centro de Investigaciones de Astronomía `Francisco J. Duarte', Mérida, Venezuela) Deep Survey of Orion, near-IR photometry from the Visible and Infrared Survey Telescope for Astronomy and low-resolution spectroscopy obtained with Hectospec at the MMT telescope, we selected 1246 photometric candidates to low-mass stars and brown dwarfs with estimated masses within 0.02 ≲ M/M⊙ ≲ 0.8 and spectroscopically confirmed a sample of 77 low-mass stars as new members of the cluster with a mean age of ˜7 Myr. We have obtained a system initial mass function of the group that can be well described by either a Kroupa power-law function with indices α3 = -1.73 ± 0.31 and α2 = 0.68 ± 0.41 in the mass ranges 0.03 ≤ M/M⊙ ≤ 0.08 and 0.08 ≤ M/M⊙ ≤ 0.5, respectively, or a Scalo lognormal function with coefficients m_c=0.21^{+0.02}_{-0.02} and σ = 0.36 ± 0.03 in the mass range 0.03 ≤ M/M⊙ ≤ 0.8. From the analysis of the spatial distribution of this numerous candidate sample, we have confirmed the east-west elongation of the 25 Orionis group observed in previous works, and rule out a possible southern extension of the group. We find that the spatial distributions of low-mass stars and brown dwarfs in 25 Orionis are statistically indistinguishable. Finally, we found that the fraction of brown dwarfs showing IR excesses is higher than for low-mass stars, supporting the scenario in which the evolution of circumstellar discs around the least massive objects could be more prolonged.

  9. Is HL Tauri and FU Orionis system in quiescence?

    NASA Technical Reports Server (NTRS)

    Lin, D. N. C.; Hayashi, M.; Bell, K. R.; Ohashi, N.

    1994-01-01

    A recent Nobeyama map of HL Tau reveals that gas is infalling in a flattened region approximately 1400 AU around the central star. The apparent motion of the gas provides the necessary condition for the formation of a Keplerian disk with a radius comparable to the size of the primordial solar nebula. The inferred mass infall rate onto the disk is approximately equal to 5 x 10(exp -6) solar mass/yr, which greatly exceeds the maximum estimate of the accretion rate onto the central star (approximately 7 x 10(exp -7) solar mass/yr). Consequently, mass must currently be accumulating in the disk. The estimated age and disk mass of HL Tau suggest that the accumulated matter has been flushed repeatedly on a timescale less than 10(exp 4) yr. Based on the similarites between their evolution patterns, we propose that HL Tau is an FU Orionis system in quiescence. In addition to HL Tau, 14 out of 86 pre-main-sequence stars in the Taurus-Auriga dark clouds have infrared luminosities much greater than their otherwise normal extinction-corrected stellar luminosities. These sources also tend to have flat spectra which may be due to the reprocessing of radiation by dusty, flattened, collapsing envelopes with infall rates a few 10(exp -6) solar mass/yr. Such rates are much larger than estimated central accretion rates for these systems, which suggests that mass must also be accumulating in these disks. If these sources are FU Orionis stars in quiescence, similar to HL Tau, their age and relative abundance imply that the FU Orionis phase occurs over a timescale of approixmately 10(exp 5) yr, and the quiescent phase between each outburst lasts approximately 10(exp 3) =10(exp 4) yr. These inferred properties are compatible with the scenario that FU Orionis outbursts are regulated by a thermal instability in the inner region of the disk.

  10. The Copernicus ultraviolet spectral atlas of Beta Orionis

    NASA Technical Reports Server (NTRS)

    Rogerson, J. B., Jr.; Upson, W. L., II

    1982-01-01

    An ultraviolet spectral atlas is presented for the B8 Ia star Beta Orionis, which has been scanned from 999 to 1561 A by the Princeton spectrometer aboard the Copernicus satellite. From 999 to 1420 A the observations have a nominal resolution of 0.05 A. At the longer wavelengths the resolution is 0.1 A. The atlas is presented in graphs. Lines identified in the spectrum are also listed.

  11. The Impact of FU Orionis Outbursts and the Solar Nebula

    NASA Technical Reports Server (NTRS)

    Bell, Robbins; Young, Richard E. (Technical Monitor)

    1998-01-01

    Protostellar systems are variable on many timescales. One of the most dramatic forms of variability known to occur in low mass stellar systems is the FU Orionis outburst (Herbig 1977). Throughout a typical outburst lasting several decades, system luminosities may be a hundred times what is typical of the quiesent state. FU Orionis outburst events are thought to have significant impact on the thermal structure of the protosolar nebula; their existence has been used to explain features in the meteoritic record from thermally induced homogenization to the formation of chondrules. Until recently, the magnitude of the likely effect from such outbursts has been largely speculative due to the lack of a detailed understanding of the outburst mechanism. Recent numerical models (Bell\\& Lin 1994) have demonstrated the viability of the observational hypothesis (Hartmann\\& Kenyon 1985) that the radiation observed during outburst is emitted by a luminous circumstellar disk transporting mass at a thousand times the quiesent rate. Light curves and color and line width evolution observed in FU Orionis systems are naturally explained by time dependent outbursting model disks (Bell et al. 1995). The radial temperature structure and shape of the disk during outburst derived from these models may be used to calculate the outburst's expected impact on primitive material at various radii throughout the disk. In this review, we will begin by discussing what is known about the FU Orionis outburst phenomenon from recent observations and theory including statistically deduced outburst timescales and observed peak temperatures. Unless covered by another author, we will discuss the evidence which suggests that outburst radiation is emitted by a circumstellar disk rather than by the star and will briefly review the thermal instability as a mechanism for outburst. We will then report on recent work which investigates the likely heating of solar nebula material due to FU Orionis outbursts

  12. High resolution spectroscopy of the new FU Orionis object BBW 76

    NASA Astrophysics Data System (ADS)

    Eisloeffel, J.; Hessman, F. V.; Mundt, R.

    1990-06-01

    High-resolution spectra of the new FU Orionis object BBW 76 are presented. Although the photometric outburst of this FU Orionis object could not be observed, its spectral characteristics clearly identify it as belonging to this class. BBW 76 shows Balmer line profiles typical for FU Orionis stars. Its absorption line spectrum and, in particular, the line widths are strikingly similar to that of FU Ori. Other similarities to FU Ori are the presence of an arclike nebula, and the FIR luminosities and color temperatures.

  13. Periodic photospheric and chromospheric modulation in Alpha Orionis (Betelgeuse)

    NASA Technical Reports Server (NTRS)

    Dupree, A. K.; Baliunas, S. L.; Hartmann, L.; Nassiopoulos, G. E.; Guinan, E. F.; Sonneborn, G.

    1987-01-01

    The bright cool supergiant Alpha Orionis has been monitored spectroscopically and photometrically over the past three years (1984-1986) in the optical and the ultraviolet wavelength regions. A 420-day periodic modulation of the flux is observed in the optical and ultaviolet continua, and in the Mg II line emission cores. Periodic photospheric pulsations are the most likely explanation of these observations. This identification is based on the large amplitude of the variation, the correlation of the continuum and chromospheric fluxes, and the length of the observed period. Pulsation may heat and extend the atmosphere of Alpha Ori and initiate the mass flow from the star.

  14. Evolution of the FU Orionis Object BBW 76

    NASA Astrophysics Data System (ADS)

    Reipurth, Bo; Hartmann, Lee; Kenyon, Scott J.; Smette, Alain; Bouchet, Patrice

    2002-10-01

    We have carried out a long-term photometric and spectroscopic monitoring program of the southern FU Orionis-type object BBW 76 spanning the period from 1982 to 1997. BBW 76 has the same radial velocity as the small cloud toward which it is projected, and for which a kinematic distance of about 1.8 kpc has been derived. We have determined a large reddening of E(B-V)~0.7 for BBW 76. Optical and infrared spectra show the change toward later spectral type with increasing wavelength characteristic of FU Orionis stars and indicative of a hot luminous disk. High-resolution echelle spectra of BBW 76 show P Cygni profiles with extended blueshifted absorption troughs at the Hα and sodium lines from a neutral, supersonic wind. Comparison of such spectra obtained at six different epochs between 1985 and 1997 reveals major changes in these Hα and sodium line profiles. For a period of 10 years from 1985, the massive absorption troughs diminished in extent and depth, until by 1994 they had all but disappeared, while at the same time the blueshifted emission peak in the Hα line increased markedly in strength. However, when observed in 1997, the absorption had increased again and the emission had diminished. We interpret this in terms of an extended period during which accretion through a circumstellar disk decreased, with a resulting decrease in wind production. But the increased activity by 1997 shows that this is not a constant decay and that the star was not about to revert to its presumably original T Tauri stage. We monitored the star with optical photometry from 1983 to 1994, during which period it decreased almost monotonically in brightness by 0.2 mag in V. Infrared J, H, and K photometry from 1983 to 1991 shows a period of monotonic fading between 1984 and 1988, followed by more irregular behavior. In a search of the Harvard plate archives we have found a plate from the year 1900 on which BBW 76 is seen at approximately its present brightness, certainly not 2 mag

  15. {lambda}(1520) {yields} {lambda}{gamma} Radiative-Decay Width

    SciTech Connect

    Vavilov, D.V.; Antipov, Yu.M.; Artamonov, A.V.; Batarin, V.A.; Victorov, V.A.; Golovkin, S.V.; Gorin, Yu.P.; Eroshin, O.V.; Kozhevnikov, A.P.; Konstantinov, A.S.; Kubarovsky, V.P.; Kurshetsov, V.F.; Landsberg, L.G.; Leontiev, V.M.; Molchanov, V.V.; Mukhin, V.A.; Patalakha, D.I.; Petrenko, S.V.; Petrukhin, A.I.; Kolganov, V.Z.

    2005-03-01

    The radiative decay {lambda}(1520) {yields} {lambda}{gamma} was recorded in the exclusive reaction p + N {yields} {lambda}(1520)K{sup +} + N at the SPHINX facility. The branching ratio for this decay and the corresponding partial width were found to be, respectively, Br[{lambda}(1520) {yields} {lambda}{gamma}] = (1.02 {+-} 0.21) x 10{sup -2} and {gamma}[{lambda}(1520) {yields} {lambda}{gamma}] = 159 {+-} 35 keV (the quoted errors are purely statistical, the systematic errors being within 15%)

  16. Proplyds Around a B1 Star: 42 Orionis in NGC 1977

    NASA Astrophysics Data System (ADS)

    Kim, Jinyoung Serena; Clarke, Cathie J.; Fang, Min; Facchini, Stefano

    2016-07-01

    We present the discovery of seven new proplyds (i.e., sources surrounded by cometary Hα emission characteristic of offset ionization fronts (IFs)) in NGC 1977, located about 30‧ north of the Orion Nebula Cluster (ONC) at a distance of ∼400 pc. Each of these proplyds is situated at projected distances 0.04–0.27 pc from the B1V star 42 Orionis (c Ori), which is the main source of UV photons in the region. In all cases the IFs of the proplyds are clearly pointing toward the common ionizing source, 42 Ori, and six of the seven proplyds clearly show tails pointing away from it. These are the first proplyds to be found around a B star, with previously known examples instead being located around O stars, including those in the ONC around θ 1 Ori C. The radii of the offset IFs in our proplyds are between ∼200 and 550 au two objects also contain clearly resolved central sources that we associate with disks of radii 50–70 au. The estimated strength of the FUV radiation field impinging on the proplyds is around 10–30 times less than that incident on the classic proplyds in the ONC. We show that the observed proplyd sizes are however consistent with recent models for FUV photoevaporation in relatively weak FUV radiation fields.

  17. Energy of the ground and 2{sup +} excited states of {sub {lambda}}{sub {lambda}}{sup 10}Be: A partial ten-body model

    SciTech Connect

    Shoeb, Mohammad; Sonika

    2009-08-15

    The energies of the ground and excited 2{sup +} states of {sub {lambda}}{sub {lambda}}{sup 10}Be have been calculated variationally in the Monte Carlo framework. The hypernucleus is treated as a partial ten-body problem in the {lambda}{lambda}+{alpha}{alpha} model where nucleonic degrees of freedom of {alpha}'s are taken into consideration ignoring the antisymmetrization between two {alpha}'s. The central two-body {lambda}N and {lambda}{lambda} and the three-body dispersive and two-pion exchange {lambda}NN forces, constrained by the {lambda}p scattering data and the observed ground state energies of {sub {lambda}}{sup 5}He and {sub {lambda}}{sub {lambda}}{sup 6}He, are employed. The product-type trial wave function predicts binding energy for the ground state considerably less than for the event reported by Danysz et al.; however, it is consistent with the value deduced assuming a {gamma} ray of 3.04 MeV must have escaped undetected in the decay of the product {sub {lambda}}{sup 9}Be* {yields} {sub {lambda}}{sup 9}Be+{gamma} of the emulsion event {sub {lambda}}{sub {lambda}}{sup 10}Be{yields} {pi}{sup -}+p+{sub {lambda}}{sup 9}Be* and for the excited 2{sup +} state closer to the value measured in the Demachi-Yanagi event. The hypernucleus {sub {lambda}}{sub {lambda}}{sup 10}Be has an oblate shape in the excited state. These results are consistent with the earlier four-body {alpha} cluster model approach where {alpha}'s are assumed to be structureless entities.

  18. Periodic modulation of the atmosphere of Alpha Orionis

    NASA Technical Reports Server (NTRS)

    Dupree, A. K.; Baliunas, S. L.; Guinan, E. F.; Hartmann, L.; Nassiopoulos, G. E.; Sonneborn, G.

    1988-01-01

    Alpha Orionis (Betelgeuse; M2 Iab) was monitored with IUE since 1984. Discovery of a 420-day periodic modulation of the flux in the optical and ultraviolet continua, and in the Mg II h and k line emission cores suggests that periodic photospheric pulsations were present from 1984 to 1986. This behavior continues through 1987. However, the general flux level of the ultraviolet continuum and the Mg II lines is decreasing, and the amplitude of the variation may be reduced. These decreases may be the emerging signature of an additional longer period. The density sensitive C II diagnostic, 2325.4/2328.1, indicates the chromospheric densities range between log N(sub e) (cm-3) = 8.7 and 9.5, but periodicities are not evident.

  19. Spectroscopy of 28Al(Lambda), 12B(Lambda), 7He(Lambda) by the (e,e'K+) Reaction

    SciTech Connect

    Akihiko Matsumura

    2010-06-30

    Hypernuclear spectroscopy by the $(e,e^{\\prime}K^+)$ reaction is one of the powerful tools to investigate precise structures of hypernuclei and to study $\\Lambda$N interaction. The second generation hypernuclear experiment at JLab Hall C(E01-011) was successfully performed in 2005, introducing the two novel experimental configurations, High resolution and large acceptance Kaon Spectrometer(HKS) and Tilt method. Thanks to these new configurations, various hypernuclei such as $^{28}_{\\Lambda}$Al, $^{12}_{\\Lambda}$B and $^{7}_{\\Lambda}$He were measured with precise energy resolution of 500 keV (FWHM). Obtained absolute binding energies and cross sections were compared with other experimental data and recent theoretical calculations based on shell model and cluster model. The results of this study provided new information on $\\Lambda$N interaction.

  20. The Unusual X-Ray Spectrum of FU Orionis

    NASA Astrophysics Data System (ADS)

    Skinner, Stephen L.; Briggs, Kevin R.; Güdel, Manuel

    2006-06-01

    FU Orionis objects (FUors) have undergone strong optical outbursts and are thought to be young low-mass stars accreting at high rates of up to M˙acc~10-4 Msolar yr-1. FUors have been extensively studied at optical and infrared wavelengths, but little is known about their X-ray properties. We have thus initiated a program aimed at searching for and characterizing their X-ray emission. First results are presented here for the prototype star FU Orionis based on observations obtained with XMM-Newton. Its CCD X-ray spectrum is unusual compared to those of accreting classical T Tauri stars (CTTSs). The cool and hot plasma components typically detected in CTTSs are present but are seen through different absorption column densities. The absorption of the cool component is consistent with AV~2.4 mag anticipated from optical studies, but the absorption of the hot component is at least 10 times larger. The origin of the excess absorption is uncertain, but cold accreting gas or a strong near-neutral wind are likely candidates. The hot plasma component accounts for most of the observed X-ray flux, and thermal models give very high temperatures kT>=5 keV. The most prominent feature in the X-ray spectrum is an exceptionally strong Fe K emission line at 6.67 keV, and weak emission from fluorescent Fe I at ~6.4 keV may also be present. The high plasma temperature clearly demonstrates that the emission is dominated by magnetic processes. We discuss possible origins of the unusual X-ray spectrum in the context of a complex physical environment that likely includes disk accretion, a strong wind, magnetic activity, and close binarity.

  1. Measurement of the Lambda b lifetime in the exclusive decay Lambda b --> J/psi Lambda.

    PubMed

    Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Ancu, L S; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Arnoud, Y; Arov, M; Arthaud, M; Askew, A; Asman, B; Jesus, A C S Assis; Atramentov, O; Autermann, C; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, P; Banerjee, S; Barberis, E; Barfuss, A-F; Bargassa, P; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Berntzon, L; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Biscarat, C; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Borissov, G; Bos, K; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Buehler, M; Buescher, V; Burdin, S; Burke, S; Burnett, T H; Buszello, C P; Butler, J M; Calfayan, P; Calvet, S; Cammin, J; Caron, S; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K; Chan, K M; Chandra, A; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Christoudias, T; Cihangir, S; Claes, D; Clément, B; Clément, C; Coadou, Y; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Crépé-Renaudin, S; Cutts, D; Cwiok, M; da Motta, H; Das, A; Davies, G; De, K; de Jong, P; de Jong, S J; De La Cruz-Burelo, E; De Oliveira Martins, C; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Ford, M; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; Garcia, C; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Gelé, D; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Gollub, N; Gómez, B; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, F; Guo, J; Gutierrez, G; Gutierrez, P; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Hanagaki, K; Hansson, P; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Hong, S J; Hooper, R; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jesik, R; Johns, K; Johnson, C; Johnson, M; Jonckheere, A; Jonsson, P; Juste, A; Käfer, D; Kahn, S; Kajfasz, E; Kalinin, A M; Kalk, J M; Kalk, J R; Kappler, S; Karmanov, D; Kasper, J; Kasper, P; Katsanos, I; Kau, D; Kaur, R; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y M; Khatidze, D; Kim, H; Kim, T J; Kirby, M H; Kirsch, M; Klima, B; Kohli, J M; Konrath, J-P; Kopal, M; Korablev, V M; Kothari, B; Kozelov, A V; Krop, D; Kryemadhi, A; Kuhl, T; Kumar, A; Kunori, S; Kupco, A; Kurca, T; Kvita, J; Lam, D; Lammers, S; Landsberg, G; Lazoflores, J; Lebrun, P; Lee, W M; Leflat, A; Lehner, F; Lellouch, J; Lesne, V; Leveque, J; Lewis, P; Li, J; Li, L; Li, Q Z; Lietti, S M; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobo, L; Lobodenko, A; Lokajicek, M; Lounis, A; Love, P; Lubatti, H J; Lyon, A L; Maciel, A K A; Mackin, D; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Makovec, N; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; Martin, B; McCarthy, R; Melnitchouk, A; Mendes, A; Mendoza, L; Mercadante, P G; Merkin, M; Merritt, K W; Meyer, A; Meyer, J; Michaut, M; Millet, T; Mitrevski, J; Molina, J; Mommsen, R K; Mondal, N K; Moore, R W; Moulik, T; Muanza, G S; Mulders, M; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Noeding, C; Nomerotski, A; Novaes, S F; Nunnemann, T; O'dell, V; O'neil, D C; Obrant, G; Ochando, C; Onoprienko, D; Oshima, N; Osta, J; Otec, R; Otero Y Garzón, G J; Owen, M; Padley, P; Pangilinan, M; Panikashvili, N; Parashar, N; Park, S-J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Perea, P M; Peters, K; Peters, Y; Pétroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M-E; Pompos, A; Pope, B G; Popov, A V; Potter, C; Prado da Silva, W L; Prosper, H B; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rakitine, A; Rangel, M S; Rani, K J; Ranjan, K; Ratoff, P N; Renkel, P; Reucroft, S; Rich, P; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rodrigues, R F; Royon, C; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A; Savage, G; Sawyer, L; Scanlon, T; Schaile, D; Schamberger, R D; Scheglov, Y; Schellman, H; Schieferdecker, P; Schliephake, T; Schmitt, C; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sekaric, J; Sengupta, S; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shivpuri, R K; Shpakov, D; Siccardi, V; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Smith, R P; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Souza, M; Spurlock, B; Stark, J; Steele, J; Stolin, V; Stone, A; Stoyanova, D A; Strandberg, J; Strandberg, S; Strang, M A; Strauss, M; Ströhmer, R; Strom, D; Strovink, M; Stutte, L; Sumowidagdo, S; Svoisky, P; Sznajder, A; Talby, M; Tamburello, P; Tanasijczuk, A; Taylor, W; Telford, P; Temple, J; Tiller, B; Tissandier, F; Titov, M; Tokmenin, V V; Tomoto, M; Toole, T; Torchiani, I; Trefzger, T; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, L; Uvarov, S; Uzunyan, S; Vachon, B; van den Berg, P J; van Eijk, B; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vartapetian, A; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Villeneuve-Seguier, F; Vint, P; Von Toerne, E; Voutilainen, M; Vreeswijk, M; Wagner, R; Wahl, H D; Wang, L; Wang, M H L S; Warchol, J; Watts, G; Wayne, M; Weber, G; Weber, M; Weerts, H; Wenger, A; Wermes, N; Wetstein, M; White, A; Wicke, D; Wilson, G W; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Yacoob, S; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yip, K; Yoo, H D; Youn, S W; Yu, C; Yu, J; Yurkewicz, A; Zatserklyaniy, A; Zeitnitz, C; Zhang, D; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zivkovic, L; Zutshi, V; Zverev, E G

    2007-10-01

    We have measured the Lambda b lifetime using the exclusive decay Lambda b --> J/psi Lambda, based on 1.2 fb(-1) of data collected with the D0 detector during 2002-2006. From 171 reconstructed Lambda b decays, where the J/psi and Lambda are identified via the decays J/psi --> mu+ mu- and Lambda --> ppi, we measured the Lambda b lifetime to be tau(Lambda b)=1.218 (+0.130)/(-0.115) (stat) +/- 0.042(syst) ps. We also measured the B0 lifetime in the decay B0 --> J/psi(mu+ mu-)K(0)/(S)(pi+ pi-) to be tau(B0)=1.501 (+0.078)/(-0.074) (stat) +/- 0.050(syst) ps, yielding a lifetime ratio of tau(Lambda b)/tau(B0)=0.811 (+0.096)/(-0.087) (stat) +/- 0.034(syst). PMID:17930660

  2. Highly efficient tabletop x-ray laser at {lambda}=41.8 nm in Pd-like xenon pumped by optical-field ionization in a cluster jet

    SciTech Connect

    Ivanova, E. P.

    2011-10-15

    The atomic-kinetic calculations of gain at 41.8 nm in Pd-like xenon are performed. The interpretation of known experiments has proved that x-ray laser in Pd-like xenon is feasible in the extremely wide range of atomic densities: 10{sup 17}{<=}[Xe{sup 8+}]{<=} 3 x 10{sup 19} cm{sup -3}. This result is due to the large cross sections (and rates) of level excitations in Pd-like xenon by electron impact. We propose a highly efficient tabletop x-ray laser pumped by optical-field ionization in a xenon cluster jet. The efficiency of {approx}0.5% is possible with a pump laser pulse energy of {>=}0.001 J and an intensity of {approx}10{sup 16} W/cm{sup 2}.

  3. Life of Lambda

    ERIC Educational Resources Information Center

    Futhey, Tracy

    2005-01-01

    In this column, the author discusses the four key questions related to the National LambdaRail (NLR) networking technology. NLR uses Dense Wave Division Multiplexing (DWDM) to enable multiple networks to coexist on a national fiber footprint, and is owned and operated not by carriers, but by the research and education community. The NLR Board…

  4. Transverse polarization of {lambda} and {lambda} hyperons in quasireal photoproduction

    SciTech Connect

    Airapetian, A.; Akopov, N.; Akopov, Z.; Avakian, R.; Avetissian, A.; Elbakian, G.; Gharibyan, V.; Marukyan, H.; Rostomyan, A.; Taroian, S.; Zohrabian, H.; Amarian, M.; Ammosov, V. V.; Gapienko, G.; Gapienko, V.; Tchuiko, B.; Andrus, A.; Bailey, P.; Bouwhuis, M.; Chiang, H. C.

    2007-11-01

    The HERMES experiment has measured the transverse polarization of {lambda} and {lambda} hyperons produced inclusively in quasireal photoproduction at a positron beam energy of 27.6 GeV. The transverse polarization P{sub n}{sup {lambda}} of the {lambda} hyperon is found to be positive while the observed {lambda} polarization is compatible with zero. The values averaged over the kinematic acceptance of HERMES are P{sub n}{sup {lambda}}=0.078{+-}0.006(stat){+-}0.012(syst) and P{sub n}{sup {lambda}}=-0.025{+-}0.015(stat){+-}0.018(syst) for {lambda} and {lambda}, respectively. The dependences of P{sub n}{sup {lambda}} and P{sub n}{sup {lambda}} on the fraction {zeta} of the beam's light-cone momentum carried by the hyperon and on the hyperon's transverse momentum p{sub T} were investigated. The measured {lambda} polarization rises linearly with p{sub T} and exhibits a different behavior for low and high values of {zeta}, which approximately correspond to the backward and forward regions in the center-of-mass frame of the {gamma}*N reaction.

  5. AN X-RAY SURVEY OF THE YOUNG STELLAR POPULATION OF THE LYNDS 1641 AND IOTA ORIONIS REGIONS

    SciTech Connect

    Pillitteri, I.; Wolk, S. J.; Myers, P.; Walter, F.; Megeath, S. T.; Allen, L.; Bally, J.; Gagne, M.; Gutermuth, R. A.; Hartman, L.; Micela, G.; Sciortino, S.; Oliveira, J. M.; Rebull, L.; Stauffer, J.

    2013-05-10

    We present an XMM-Newton survey of the part of the Orion A cloud south of the Orion Nebula. This survey includes the Lynds 1641 (L1641) dark cloud, a region of the Orion A cloud with very few massive stars and hence a relatively low ambient UV flux, and the region around the O9 III star {iota} Orionis. In addition to proprietary data, we used archival XMM data of the Orion Nebula Cluster (ONC) to extend our analysis to a major fraction of the Orion A cloud. We have detected 1060 X-ray sources in L1641 and the {iota} Ori region. About 94% of the sources have Two Micron All Sky Survey and Spitzer counterparts, 204 and 23 being Class II and Class I or protostar objects, respectively. In addition, we have identified 489 X-ray sources as counterparts to Class III candidates, given they are bright in X-rays and appear as normal photospheres at mid-IR wavelengths. The remaining 205 X-ray sources are likely distant active galactic nuclei or other galactic sources not related to Orion A. We find that Class III candidates appear more concentrated in two main clusters in L1641. The first cluster of Class III stars is found toward the northern part of L1641, concentrated around {iota} Ori. The stars in this cluster are more evolved than those in the Orion Nebula. We estimate a distance of 300-320 pc for this cluster showing that it is in the foreground of the Orion A cloud. Another cluster rich in Class III stars is located in L1641 South and appears to be a slightly older cluster embedded in the Orion A cloud. Furthermore, other evolved Class III stars are found north of the ONC toward NGC 1977.

  6. Reinvestigating the Lambda Boo Stars

    NASA Astrophysics Data System (ADS)

    Cheng, Kwang-Ping; Corbally, C. J.; Gray, R. O.; Murphy, S.; Neff, J. E.; Desai, A.; Newsome, I.; Steele, P.

    2014-01-01

    The peculiar nature of Lambda Bootis was first introduced in 1943. Subsequently, Lambda Boo stars have been slowly recognized as a group of A-type Population I dwarfs that show mild to extreme deficiencies of iron-peak elements, although C, N, O, and S can be near solar. MK classification criteria include broad hydrogen lines, a weak metallic-line spectrum compared to MK standards, coupled with a particularly weak Mg II 4481 line. This intriguing stellar class has recently regained the spotlight because of the directly imaged planets around a confirmed Lambda Boo star-HR 8799 and a probable Lambda Boo star-Beta Pictoris. The possible link between Lambda Boo stars and planet-bearing stars motivates us to study Lambda Boo stars systematically. However, Lambda Boo candidates published in the literature have been selected using widely different criteria. The Lambda Boo class has become somewhat of a "grab bag" for any peculiar A-type stars that didn't fit elsewhere. In order to determine the origin of Lambda Boo stars’ low abundances and to better discriminate between theories explaining the Lambda Boo phenomenon, a refined working definition of Lambda Boo stars is needed. We have re-evaluated all published Lambda Boo candidates and their existing spectra. After applying a consistent set of optical/UV classification criteria, we identified over 60 confirmed and over 20 probable Lambda Boo stars among all stars that have been suggested as Lambda Boo candidates. We are obtaining new observations for those probable Lambda Boo stars. We also have explored the possible link between debris disks and Lambda Boo Stars.

  7. Variational calculations of the {Lambda}-separation energy of the {sub {Lambda}}{sup 17}O hypernucleus

    SciTech Connect

    Usmani, A.A.; Pieper, S.C.; Usmani, Q.N.

    1995-05-01

    Variational Monte Carlo calculations have been made for the {sub {Lambda}}{sup 17}O hypernucleus using realistic two- and three-baryon interactions. A two-pion exchange potential with spin- and space-exchange components is used for the {Lambda}{ital N} potential. Three-body two-pion exchange and strongly repulsive dispersive {Lambda}{ital NN} interactions are also included. The trial wave function is constructed from pair- and triplet-correlation operators acting on a single-particle determinant. These operators consist of central, spin, isospin, tensor, and three-baryon potential components. A cluster Monte Carlo method is developed for noncentral correlations and is used with up to four-baryon clusters in our calculations. The three-baryon {Lambda}{ital NN} force is discussed.

  8. Very low-luminosity Class I/flat outflow sources in σ Orionis

    NASA Astrophysics Data System (ADS)

    Riaz, B.; Thompson, M.; Whelan, E. T.; Lodieu, N.

    2015-01-01

    We present an optical to submillimetre multiwavelength study of two very low-luminosity Class I/flat systems, Mayrit 1701117 and Mayrit 1082188, in the σ Orionis cluster. We performed moderate-resolution (R ˜ 1000) optical (˜0.4-0.9 μm) spectroscopy with the Cassegrain Twin Spectrograph (TWIN) spectrograph at the Calar Alto 3.5-m telescope. The spectra for both sources show prominent emission in accretion- and outflow-associated lines. The mean accretion rate measured from multiple line diagnostics is 6.4 × 10-10 M⊙ yr-1 for Mayrit 1701117 and 2.5 × 10-10 M⊙ yr-1 for Mayrit 1082188. The outflow mass-loss rates for the two systems are similar and estimated to be ˜1 × 10-9 M⊙ yr-1. The activity rates are within the range observed for low-mass Class I protostars. We obtained submillimetre continuum observations with the Submillimetre Common-User Bolometer Array (SCUBA-2) bolometer at the James Clerk Maxwell Telescope. Both objects are detected at a ≥5σ level in the SCUBA-2 850-μm band. The bolometric luminosity of the targets as measured from the observed spectral energy distribution over ˜0.8-850 μm is 0.18 ± 0.04 L⊙ for Mayrit 1701117 and 0.16 ± 0.03 L⊙ for Mayrit 1082188 and is in the very low mass range. The total dust+gas mass derived from submillimetre fluxes is ˜36 MJup and ˜22 MJup for Mayrit 1701117 and Mayrit 1082188, respectively. There is the possibility that some of the envelope material might be dissipated by the strong outflows driven by these sources, resulting in a final mass of the system close to or below the substellar limit.

  9. A WIYN Lithium Survey for Young Stars in the λ Orionis Star-Forming Region

    NASA Astrophysics Data System (ADS)

    Dolan, Christopher J.; Mathieu, Robert D.

    1999-11-01

    We have found 72 pre-main-sequence (PMS) stars near the center of the λ Orionis star-forming region by spectroscopically testing a magnitude-limited sample for the presence of lithium λ6708 absorption, a diagnostic of youth. All of these stars show large lithium equivalent widths and radial velocities consistent with Orion membership, but only two were discovered previously via Hα or X-ray surveys. Comparison with PMS evolutionary tracks show that the low-mass star formation did not begin prior to the initiation of high-mass star formation 5-7 Myr ago. However, the subsequent detailed star formation history is model dependent. Baraffe et al. isochrones imply that high- and low-mass stars began to form together 5-7 Myr ago, with the low-mass stellar formation ceasing abruptly 1 Myr ago. On the other hand, D'Antona & Mazzitelli isochrones indicate a narrow spread of PMS ages, which suggests a burst of low-mass star formation 1-2 Myr ago. Furthermore, kinematic arguments require that the parent molecular cloud gravitationally bound the stars together until recently, but at present the requisite gas mass is not visible. This leads us to conjecture that both the high- and low-mass stars were in a tightly bound cluster until a supernova blast about 1 Myr ago disrupted the parent cloud. This supernova also impacted on the PMS formation process by either (1) ceasing formation through removal of the gas supply or (2) triggering star births via cloud compression, depending on choice of stellar evolution models. Finally, we find that despite their youth, only four of the 72 PMS stars have T Tauri-like Hα emission, suggesting the absence of accretion disks. We conjecture that this may be the result of photoevaporation of the disks while the low-mass stars were in much closer proximity to the OB stars prior to becoming gravitationally unbound.

  10. Lambda Calculi: A Guide

    NASA Astrophysics Data System (ADS)

    Hankin, Chris

    One of the universal notions of programming languages is functional abstraction. The methods of Java and the functions defined and used in functional programming languages, such as Haskell, are instances of this general notion. The inspiration for this form of abstraction mechanism comes from Mathematical Logic; notably Church's λ(lambda)-calculi and Schönfinkel's and Curry's Combinatory Logic. A proper study of these foundations leads to a better understanding of some of the fundamental issues in Computer Science.

  11. {Lambda}* hypernuclei with chiral dynamics

    SciTech Connect

    Uchino, Toshitaka; Hyodo, Tetsuo; Oka, Makoto

    2011-10-21

    As a strangeness S = -1 and baryon number B = 2 system, the two-body bound state of {Lambda}* = {Lambda}(1405) and a nucleon is studied. To solve the {Lambda}*N system, we construct the {Lambda}*N potential by extending the Juelich model with couplings estimated in the chiral unitary approach. We have the {Lambda}*N quasi-bound state with the mass, M{sub {Lambda}}*N{approx}2366 MeV which is shallowly bound with the binding energy B{approx}9 MeV in terms of the K-barNN system. Decay width of the fall apart process, where the {Lambda}*N resonance decays to {pi}{Sigma}N with a nucleon being as a spectator, is estimated to be {Gamma}{sub F.A}{approx}49 MeV.

  12. Discovery of polarized light scattered by dust around Alpha Orionis

    NASA Technical Reports Server (NTRS)

    Mcmillan, R. S.; Tapia, S.

    1978-01-01

    Following the suggestion by Jura and Jacoby (1976), linearly polarized blue continuum starlight scattered by the dust shell around the M2 Iab star Alpha Orionis (Betelgeuse) has been discovered. The polarization has been traced in the NE, NW, SE, and SW directions and has positive (tangential) orientation. Some asymmetry of the optical depth in the shell exists 15 and 30 arcsec from the star. In the NE direction the polarization was measured as far as 90 arcsec (17,000 AU) from the star. The dependence of the average intensity of the scattered light from the nebula on angular distance from the star is more consistent with an inverse-square density law than with inverse 1.5 or inverse-cube laws. Assuming that the density is proportional to the inverse square of distance from the star, the scattering optical depth in blue light along a radius of 0.03 arcsec is no more than 0.15 + or - 0.05. Future observations of the wavelength dependence of polarization will allow a determination of grain size.

  13. X-ray Variability in the Hot Supergiant zgr Orionis.

    PubMed

    Berghöfer, T W; Schmitt, J H

    1994-09-16

    Hot massive stars represent only a small fraction of the stellar population of the galaxy, but their enormous luminosities make them visible over large distances. Therefore, they are ideal standard candles, used to determine distances of near galaxies. Their mass loss due to supersonic winds driven by radiation pressure contributes significantly to the interstellar medium and thus to the chemical evolution of galaxies. All hot stars are soft x-ray sources; in contrast to the sun with its highly variable x-ray flux, long time scale x-ray variability is not common among hot stars. An analysis is presented here of an unusual increase in x-ray flux observed with the roentgen observatory satellite during a period of 2 days for the hot supergiant zeta Orionis, the only episode of x-ray variability that has been found in a hot star. These observations provide the most direct evidence so far for the scenario of shock-heated gas in the winds of hot stars. PMID:17770897

  14. Spin correlations in the {Lambda}{Lambda} and {Lambda}{Lambda}-bar systems generated in relativistic heavy-ion collisions

    SciTech Connect

    Lyuboshitz, V. L.; Lyuboshitz, V. V.

    2010-05-15

    Spin correlations for the {Lambda}{Lambda} and {Lambda}{Lambda}-bar pairs, generated in relativistic heavy-ion collisions, and related angular correlations at the joint registration of hadronic decays of two hyperons, in which space parity is not conserved, are analyzed. The correlation tensor components can be derived from the double angular distribution of products of two decays by the method of 'moments'. The properties of the 'trace' of the correlation tensor (a sum of three diagonal components), determining the relative fractions of the triplet states and singlet state of respective pairs, are discussed. Spin correlations for two identical particles ({Lambda}{Lambda}) and two nonidentical particles ({Lambda}{Lambda}-bar) are considered from the viewpoint of the conventional model of one-particle sources. In the framework of this model, correlations vanish at sufficiently large relative momenta. However, under these conditions, in the case of two nonidentical particles ({Lambda}{Lambda}-bar) a noticeable role is played by two-particle annihilation (two-quark, two-gluon) sources, which lead to the difference of the correlation tensor from zero. In particular, such a situation may arise when the system passes through the 'mixed phase.'

  15. Variable X-ray Emission from FU Orionis

    NASA Astrophysics Data System (ADS)

    Skinner, Steve L.; Guedel, M.; Briggs, K. R.; Lamzin, S. A.; Sokal, K. R.

    2009-05-01

    FU Orionis is the prototype of a small but remarkable class of pre-main sequence stars ('FUors') that have undergone large optical outbursts thought to be linked to episodic accretion. FU Ori increased in optical brightness by about 6 mag in 1936-37 and is still in slow decline. Because of their high accretion rates, FUors are good candidates for exploring potential effects of accretion on X-ray emission. A recently completed survey of FUors with XMM-Newton detected X-rays from FU Ori and V1735 Cyg. We present new results from a sensitive 99 ksec (1.15 day) follow-up X-ray observation of FU Ori with Chandra. The Chandra ACIS-S CCD spectrum confirms the presence of a cool plasma component (kT < 1 keV) viewed under moderate absorption and a much hotter component (kT > 3 keV), viewed under high absorption, in accord with previous XMM results. The uninterrupted Chandra light curve shows that the hot component is slowly variable on a timescale of one day, but no variability is detected in the cool component. The slow variability and high plasma temperature point to a magnetic origin for the hot component, but other mechanisms (including accretion) may be responsible for the cool non-variable component. We will discuss these new results in the context of what is known about FU Ori from previous observations, including XMM (Skinner et al. 2006, ApJ, 643, 995) and HST (Kravtsova et al. 2007, Ast. Ltrs., 33, 755).

  16. {Lambda} single-particle energies

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.; Sami, M.

    1995-08-01

    We are continuing our work on the {Lambda} hyperon single-particle (s.p.) energies and their interpretation in terms of the basic {Lambda}-nuclear interactions. In particular we are interpreting the results obtained by S.C. Pieper, A. Usmani and Q.N. Usmani. We obtain about 30 MeV for the repulsive contribution of the three-body {Lambda}NN forces in nuclear matter. We are able to exclude purely {open_quotes}dispersive{close_quotes} {Lambda}NN forces. We are investigating the mix of dispersive and two-pion-exchange {Lambda}NN forces which provide a fit to the s.p. data. For interactions, which provide a fit to the s.p. data, the {Lambda} binding energy as a function of the nuclear matter density shows characteristic saturation features with a maximum at a density not very different from that of normal nuclear matter. We obtain a more precise measure of the space-exchange part of the {Lambda}-nuclear force than was previously available, corresponding to an exchange parameter {approx_equal} 0.32. The space-exchange force is rather directly related to the effective mass of a {Lambda} in the nuclear medium and turns out to be about 70% of its free mass. As a result, we also obtain a much better value for the p-state {Lambda}-nucleus potential which is about 40% of the s-state potential. The A binding to nuclear matter is determined to be {approx_equal} 28 MeV.

  17. HERMES measurements of {lambda} polarization

    SciTech Connect

    Rith, Klaus

    2007-06-13

    The HERMES experiment at DESY has measured the transfer of polarization from longitudinally polarized 27.6 GeV positrons to {lambda} hyperons produced in semi-inclusive deep-inelastic scattering from unpolarized gas targets internal to the electron/positron ring of the HERA collider. The longitudinal spin transfer coefficient is found to be D{sub LL'}{sup {lambda}} = 0.11 {+-} 0.10 (stat) {+-} 0.03 (syst) at an average fractional energy carried by the {lambda} hyperon = 0.45.

  18. A THIRD MASSIVE STAR COMPONENT IN THE {sigma} ORIONIS AB SYSTEM

    SciTech Connect

    Simon-Diaz, S.; Caballero, J. A.; Lorenzo, J.

    2011-11-20

    We report on the detection of a third massive star component in the {sigma} Orionis AB system, traditionally considered as a binary system. The system has been monitored by the IACOB Spectroscopic Survey of Northern Massive Stars program, obtaining 23 high-resolution FIES-NOT spectra with a time span of {approx}2.5 years. The analysis of the radial velocity curves of the two spectroscopic components observed in the spectra has allowed us to obtain the orbital parameters of the system, resulting in a high eccentric orbit (e {approx} 0.78) with an orbital period of 143.5 {+-} 0.5 days. This result implies the actual presence of three stars in the {sigma} Orionis AB system when combined with previous results obtained from the study of the astrometric orbit (with an estimated period of {approx}157 years).

  19. X-RAY EMISSION FROM THE FU ORIONIS STAR V1735 CYGNI

    SciTech Connect

    Skinner, Stephen L.; Sokal, Kimberly R.; Guedel, Manuel; Briggs, Kevin R.

    2009-05-01

    The variable star V1735 Cyg (=Elias 1-12) lies in the IC 5146 dark cloud and is a member of the class of FU Orionis objects whose dramatic optical brightenings are thought to be linked to episodic accretion. We report the first X-ray detections of V1735 Cyg and a deeply embedded class I protostar lying 24'' to its northeast. X-ray spectra obtained with EPIC on XMM-Newton reveal very high-temperature plasma (kT > 5 keV) in both objects, but no large flares. Such hard X-ray emission is not anticipated from accretion shocks and is a signature of magnetic processes. We place these new results into the context of what is presently known about the X-ray properties of FU Orionis stars and other accreting young stellar objects.

  20. Moderate-resolution spectral standards from lambda 5600 to lambda 9000

    NASA Technical Reports Server (NTRS)

    Allen, Lori E.; Strom, Karen M.

    1995-01-01

    We present a grid of stellar classification spectra of moderate resolution (R approximately 1500) in the range lambda lambda 5600-9000 A, compiled from high signal-to noise spectra of 275 stars, most in the open clusters Praesepe and M67. The grid covers dwarfs from types B8 through M5, giants from G8 through M7, and subgiants from F5 through K0. We catalog atomic and molecular absorption features useful for stellar classification, and demonstrate the use of luminosity-sensitive features to distinguish between late-type dwarf and giant stars. The entire database is made available in digital format on anonymous ftp and through the World Wide Web.

  1. Zeeman effect in the X-ray star candidates HD 77581 and theta super 2 Orionis.

    NASA Technical Reports Server (NTRS)

    Kemp, J. C.; Wolstencroft, R. D.

    1973-01-01

    The discovery of Zeeman effects is reported in HD 77581 and theta super 2 Orionis, optical candidates for the X-ray sources Vela XR-1 and 2U 0525-06, respectively. The maximum longitudinal magnetic fields recorded were -10,000 G in HD 77581 and +1500 G in theta super 2 Ori. Various polarimetric data are also given, including evidence for a variable linear polarization in HD 77581.

  2. Continuum optical circular polarisation in the young O star Theta 1 Orionis C?

    NASA Astrophysics Data System (ADS)

    Moffat, A. F. J.; Eversberg, T.

    2000-06-01

    Recently, Donati & Wade (1999) have claimed rather spectacular, large, variable circular polarisation in the optical continuum of Theta 1 Orionis C, obtained with the échelle spectropolarimeter MuSiCoS. However, based on experience with the William-Wehlau spectropolarimeter, a similar unit using two fiber feeds, we suggest that this is the spurious result of instrumental effects. We propose a remedy to eliminate the effect.

  3. GRAVITATIONAL LENSING CORRECTIONS IN FLAT {Lambda}CDM COSMOLOGY

    SciTech Connect

    Kantowski, Ronald; Chen Bin; Dai Xinyu E-mail: Bin.Chen-1@ou.ed

    2010-08-01

    We compute the deflection angle to order (m/r {sub 0}){sup 2} and m/r{sub 0} x {Lambda}r {sup 2}{sub 0} for a light ray traveling in a flat {Lambda}CDM cosmology that encounters a completely condensed mass region. We use a Swiss cheese model for the inhomogeneities and find that the most significant correction to the Einstein angle occurs not because of the nonlinear terms but instead occurs because the condensed mass is embedded in a background cosmology. The Swiss cheese model predicts a decrease in the deflection angle of {approx}2% for weakly lensed galaxies behind the rich cluster A1689 and that the reduction can be as large as {approx}5% for similar rich clusters at z {approx} 1. Weak-lensing deflection angles caused by galaxies can likewise be reduced by as much as {approx}4%. We show that the lowest order correction in which {Lambda} appears is proportional to m/r{sub 0} x {radical}({Lambda}r{sub 0}{sup 2}) and could cause as much as a {approx}0.02% increase in the deflection angle for light that passes through a rich cluster. The lowest order nonlinear correction in the mass is proportional to m/r{sub 0}x{radical}(m/r{sub 0}) and can increase the deflection angle by {approx}0.005% for weak lensing by galaxies.

  4. Using FU Orionis outbursts to constrain self-regulated protostellar disk models

    NASA Technical Reports Server (NTRS)

    Bell, K. R.; Lin, D. N. C.

    1994-01-01

    One-dimensional, convective, vertical structure models and one dimensional time-dependent, radial diffusion models are combined to create a self-consistent picture in which FU Orionis outbursts occur in young stellar objects (YSOs) as the result of a large-scale, self-regulated, thermal ionization instability in the surrounding protostellar accretion disk. Although active accretion disks have long been postulated to be ubiqitous among low-mass YSOs, few constraints have until now been imposed on physical conditions in these disks. By fitting the results of time-dependent disk models to observed timescales of FU Orionis events, we estimate the magnitude of the effective viscous stress in the inner disk (r approximately less than 1 AU) to be, in accordance with an ad hoc 'alpha' prescription, the product of the local sound speed, pressure scale height, and an efficiency factor alpha of 10(exp -4) where hydrogen is neutral and 10(exp 3) where hydrogen is ionized. We hypothesize that all YSOs receive infall onto their outer disks which is steady (or slowly declining with time) and that FU Orionis outbursts are self-regulated, disk outbursts which occur only in systems which transport matter inward at a rate sufficiently high to cause hydrogen to be ionized in the inner disk. We estimate a critical mass flux of dm(sub crit)/dt = 5 x 10(exp 7) solar mass/yr independent of the magnitude of alpha for systems with one solar mass, three solar radius central objects. Infall accretion rates in the range of dm(sub in)/dt = 1-10) x 10(exp -6) solar mass/yr produce observed FU Orionis timescales consistent with estimates of spherical molecular cloud core collapse rates. Modeled ionization fronts are typically initiated near the inner edge of the disk and propogate out to a distance of several tens of stellar radii. Beyond this region, the disk transports mass steadily inward at the supplied constant infall rate. Mass flowing through the innermost disk annulus is equal to dm

  5. Experimental Studies of Hypernuclear Structure and the {lambda}N and {lambda}NN Interactions

    SciTech Connect

    Tamura, H.

    2008-04-29

    The {lambda}NN three-body force, through {lambda}N-{sigma}N coupling, plays an important role in the structure of {lambda} hypernuclei. We have been studying the {lambda}N interaction via hypernuclear {gamma}-ray spectroscopy experiments and obtained the effective interaction strengths of the spin-dependent {lambda}N interactions. In addition, a possible effect of the {lambda}NN three-body force is being investigated from precise level schemes of light {lambda} hypernuclei. The {lambda}NN three-body force can also be studied from the structure of neutron-rich {lambda} hypernuclei by using the ({pi}{sup -},K{sup +}) reaction.

  6. Alpha particles accompanying the weak decay of {sub {lambda}}{sup 10}Be and {sub {lambda}}{sup 10}B hypernuclei

    SciTech Connect

    Majling, L. Kuzmin, V. A. Tetereva, T. V.

    2006-05-15

    The possibility of a detailed investigation of weak {lambda}N interaction in the {sub {lambda}}{sup 10}Be and {sub {lambda}}{sub /10}B hypernuclei, which stand out owing to their {alpha}{alpha}N{lambda} cluster structure, is discussed. The detection of a few groups of correlated {alpha}{alpha} pairs will furnish information about decays to specific states of product nuclei ({sup 8}Be*, {sup 8}Li, {sup 8}B), thereby paving the way to a phenomenological analysis of the weak decays of p-shell hypernuclei. The ratios of the intensities of individual alpha-particle groups to be measured in experiments at the cyclotron of the Joint Institute for Nuclear Research (JINR, Dubna) will provide a useful criterion for choosing an appropriate model of weak {lambda}N interaction. The current state of hypernuclear physics is briefly reviewed.

  7. Measurements of J/{psi} and {psi}(2S) decays into {lambda}{lambda}{pi}{sup 0} and {lambda}{lambda}{eta}

    SciTech Connect

    Ablikim, M.; Bai, J. Z.; Cai, X.; Chen, H. S.; Chen, H. X.; Chen, J. C.; Chen, Jin; Chen, Y. B.; Chu, Y. P.; Deng, Z. Y.; Du, S. X.; Fang, J.; Fang, S. S.; Gao, C. S.; Gu, S. D.; Guo, Y. N.; He, K. L.; Heng, Y. K.; Hu, H. M.; Hu, T.

    2007-11-01

    Using 58x10{sup 6} J/{psi} and 14x10{sup 6} {psi}(2S) events collected by the BESII detector at the BEPC, branching fractions or upper limits for the decays J/{psi} and {psi}(2S){yields}{lambda}{lambda}{pi}{sup 0} and {lambda}{lambda}{eta} are measured. For the isospin violating decays, the upper limits are determined to be B(J/{psi}{yields}{lambda}{lambda}{pi}{sup 0})<6.4x10{sup -5} and B[{psi}(2S){yields}{lambda}{lambda}{pi}{sup 0}]<4.9x10{sup -5} at the 90% confidence level. The isospin conserving process J/{psi}{yields}{lambda}{lambda}{eta} is observed for the first time, and its branching fraction is measured to be B(J/{psi}{yields}{lambda}{lambda}{eta})=(2.62{+-}0.60{+-}0.44)x10{sup -4}, where the first error is statistical and the second one is systematic. No {lambda}{lambda}{eta} signal is observed in {psi}(2S) decays, and B[{psi}(2S){yields}{lambda}{lambda}{eta}]<1.2x10{sup -4} is set at the 90% confidence level. Branching fractions of J/{psi} decays into {sigma}{sup +}{pi}{sup -}{lambda} and {sigma}{sup -}{pi}{sup +}{lambda} are also reported, and the sum of these branching fractions is determined to be B(J/{psi}{yields}{sigma}{sup +}{pi}{sup -}{lambda}+c.c.)=(1.52{+-}0.08{+-}0.16)x10{sup -3}.

  8. The degenerate spin-flip doublet (3{sup +}/2,5{sup +}/2) of {sub {lambda}}{sup 9}Be

    SciTech Connect

    Shoeb, Mohammad; Sonika

    2009-05-15

    The energy of the degenerate doublet (3{sup +}/2,5{sup +}/2) of {sub {lambda}}{sup 9}Be, treating it as a partially nine-body system in the {lambda}{alpha}{alpha} cluster model, has been calculated in the variational Monte Carlo framework. A simplified treatment, with the central two-body Urbana type {lambda}N and the three-body dispersive and two-pion exchange {lambda}NN forces along with the central two- and three-body correlations, is found to be adequate in explaining the energy of observed {gamma}-ray transition from the excited degenerate doublet to the ground state. The hypernucleus {sub {lambda}}{sup 9}Be is highly deformed and has an oblate shape in the excited state. The results of the present work are consistent with the earlier three-body cluster model analyzes of {sub {lambda}}{sup 9}Be.

  9. {Lambda}K*{Lambda}(1116) photoproduction and nucleon resonances

    SciTech Connect

    Kim, Sang-Ho; Kim, Hyun-Chul; Nam, Seung-il; Oh, Yongseok

    2011-10-21

    In this presentation, we report our recent studies on the {Lambda}K*{Lambda}(1116) photoproduction off the proton target, using the tree-level Born approximation, via the effective Lagrangian approach. In addition, we include the nine (three- or four-star confirmed) nucleon resonances below the threshold {radical}(s{sub th}){approx_equal}2008 MeV, to interpret the discrepancy between the experiment and previous theoretical studies, in the vicinity of the threshold region. From the numerical studies, we observe that the S{sub 11}(1535) and S11(1650) play an important role for the cross-section enhancement near the {radical}(s{sub th}). It also turns out that, in order to reproduce the data, we have the vector coupling constants gK*S{sub 11}(1535){Lambda} = (7.0{approx}9.0) and gK*S{sub 11}(1650){Lambda} (5.0{approx}6.0).

  10. A new three-baryon-force in {lambda}{lambda} hypernuclei

    SciTech Connect

    Nemura, Hidekatsu

    2008-04-29

    We describe a few-body calculation of {sub {lambda}}{sub {lambda}}{sup 5}H as well as {sub {lambda}}{sub {lambda}}{sup 4}H and {sub {lambda}}{sub {lambda}}{sup 6}He taking account fully coupled-channel two-baryon potentials acting among the octet of baryons. The wave function includes not only pnn{lambda}{lambda} and ppnn{xi}{sup -} components but also pnn{lambda}{sigma}{sup 0}, ppn{lambda}{sigma}{sup -}, pnn{sigma}{sup 0}{sigma}{sup 0} and ppn{sigma}{sup 0}{sigma}{sup -}. An effective YY potential based on Nijmegen model D is used. We find that the pnn{lambda}{sigma}{sup 0} and ppn{lambda}{sigma}{sup -} components play an important role in producing the {sub {lambda}}{sub {lambda}}{sup 5}H bound state. The present result requires the introduction of a new coupled-channel three-body-force, N{lambda}{lambda}--NN{xi}, if the intermediate pnn{lambda}{sigma}{sup 0} and ppn{lambda}{sigma}{sup -} states are eliminated from the model space.

  11. AN ANALYSIS OF THE ENVIRONMENTS OF FU ORIONIS OBJECTS WITH HERSCHEL

    SciTech Connect

    Green, Joel D.; Evans, Neal J. II; Merello, Manuel; Kospal, Agnes; Herczeg, Gregory; Quanz, Sascha P.; Henning, Thomas; Bouwman, Jeroen; Van Kempen, Tim A.; Lee, Jeong-Eun; Dunham, Michael M.; Meeus, Gwendolyn; Chen, Jo-hsin; Guedel, Manuel; Liebhart, Armin; Skinner, Stephen L.

    2013-08-01

    We present Herschel-HIFI, SPIRE, and PACS 50-670 {mu}m imaging and spectroscopy of six FU Orionis-type objects and candidates (FU Orionis, V1735 Cyg, V1515 Cyg, V1057 Cyg, V1331 Cyg, and HBC 722), ranging in outburst date from 1936 to 2010, from the 'FOOSH' (FU Orionis Objects Surveyed with Herschel) program, as well as ancillary results from Spitzer Infrared Spectrograph and the Caltech Submillimeter Observatory. In their system properties (L{sub bol}, T{sub bol}, and line emission), we find that FUors are in a variety of evolutionary states. Additionally, some FUors have features of both Class I and II sources: warm continuum consistent with Class II sources, but rotational line emission typical of Class I, far higher than Class II sources of similar mass/luminosity. Combining several classification techniques, we find an evolutionary sequence consistent with previous mid-IR indicators. We detect [O I] in every source at luminosities consistent with Class 0/I protostars, much greater than in Class II disks. We detect transitions of {sup 13}CO (J{sub up} of 5-8) around two sources (V1735 Cyg and HBC 722) but attribute them to nearby protostars. Of the remaining sources, three (FU Ori, V1515 Cyg, and V1331 Cyg) exhibit only low-lying CO, but one (V1057 Cyg) shows CO up to J = 23 {yields} 22 and evidence for H{sub 2}O and OH emission, at strengths typical of protostars rather than T Tauri stars. Rotational temperatures for 'cool' CO components range from 20 to 81 K, for {approx} 10{sup 50} total CO molecules. We detect [C I] and [N II] primarily as diffuse emission.

  12. Long-Wavelength Excesses of FU Orionis Objects: Flared Outer Disks or Infalling Envelopes?

    NASA Astrophysics Data System (ADS)

    Zhu, Zhaohuan; Hartmann, Lee; Calvet, Nuria; Hernandez, Jesus; Tannirkulam, Ajay-Kumar; D'Alessio, Paola

    2008-09-01

    The mid- to far-infrared emission of the outbursting FU Orionis objects has been attributed either to a flared outer disk or to an infalling envelope. We revisit this issue using detailed radiative transfer calculations to model the recent, high signal-to-noise ratio data from the IRS instrument on the Spitzer Space Telescope. In the case of FU Ori, we find that a physically plausible flared disk irradiated by the central accretion disk matches the observations. Building on our previous work, our accretion disk model with outer disk irradiation by the inner disk reproduces the spectral energy distribution between ~4000 Å and ~40 μm. Our model is consistent with near-infrared interferometry, but there are some inconsistencies with mid-infrared interferometric results. Including the outer disk allows us to refine our estimate of the outer radius of the outbursting, high mass accretion rate disk in FU Ori as ~0.5 AU, which is a crucial parameter in assessing theories of the FU Orionis phenomenon. We are able to place an upper limit on the mass infall rate of any remnant envelope infall rate to ~7 × 10-7 M⊙ yr -1 assuming a centrifugal radius of 200 AU. The FUor BBW 76 is also well modeled by a 0.6 AU inner disk and a flared outer disk. However, V1515 Cyg requires an envelope with an outflow cavity to adequately reproduce the IRS spectrum. In contrast with the suggestion by Green et al., we do not require a flattened envelope to match the observations; the inferred cavity shape is qualitatively consistent with typical protostellar envelopes. This variety of dusty structures suggests that the FU Orionis phase can be present at either early or late stages of protostellar evolution.

  13. Six-Body variational Monte Carlo study of {sub {lambda}}{sub {lambda}}{sup 6}He

    SciTech Connect

    Usmani, Q.N.; Sharma, Bhupali; Bodmer, A.R.

    2004-12-01

    Variational Monte Carlo calculations are carried out for {sub {lambda}}{sub {lambda}}{sup 6}He using realistic NN, NNN, and phenomenological {lambda}N and {lambda}NN interactions. For the {lambda}{lambda} interaction we employ the various phase equivalent Nijmegen interactions. By incorporating the various components of {lambda}-nuclear interactions in stages, and keeping B{sub {lambda}}({sub {lambda}}{sup 5}He) around 3.12 MeV, it is demonstrated that the incremental energy {delta}B{sub {lambda}}{sub {lambda}} for {sub {lambda}}{sub {lambda}}{sup 6}He is sensitive to the three-body {lambda}NN force and the exchange part of the {lambda}N interaction. The {lambda}{lambda} interaction obtained is only somewhat weaker than the {lambda}N interaction. We also report the results for the rearrangement energy of the {alpha} core. We discuss the implications of our results.

  14. Discovery of two distorted interstellar bubbles. [found about T Orionis variable LL Ori and Zeta Oph

    NASA Technical Reports Server (NTRS)

    Gull, T. R.; Sofia, S.

    1979-01-01

    During an extensive program of direct imagery of emission nebulae, arcuate structures have been found around two stars. A well-defined shocklike structure is found about the T Orionis variable LL Ori, located to the side of the Orion Nebula. A less extensive shocklike structure is also found about the runaway star Zeta Oph. These structures can be best described in terms of distorted interstellar bubbles. A direct consequence of this interpretation is an independent estimate of the rates of mass loss for these stars.

  15. Photometric Study of the FU Orionis Object BBW 76 from the Bamberg Observatory Southern Sky Survey

    NASA Astrophysics Data System (ADS)

    Borisova, A.; Tsvetkova, K. P.; Tsvetkov, M. K.

    2006-04-01

    The Bamberg Observatory Southern Sky Survey provided 93 photographic plates with the FU Orionis object BBW 76, clearly detectable in the time interval 1963-1976. We perform aperture photometry of BBW 76 from the 2 x 2 degrees area near target star scanned with the Epson Expression 1640 XL flatbed scanner. For each plate a transformation of plate magnitude to the GSC 2.2 magnitudes in B photographic band was found out for selected reference stars, and used for deriving B magnitudes of BBW 76. The analysis of the photometric behaviour of BBW 76 is presented.

  16. Study of B{yields}{lambda}{sub c}{lambda}{sub c} and B{yields}{lambda}{sub c}{lambda}{sub c}K

    SciTech Connect

    Cheng, H.-Y.; Hsiao, Y.-K.; Chua, C.-K.

    2009-06-01

    We study the doubly charmful two-body and three-body baryonic B decays B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -} and B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K. As pointed out before, a naive estimate of the branching ratio O(10{sup -8}) for the latter decay is too small by 3 to 4 orders of magnitude compared to experiment. Previously, it has been shown that a large enhancement for the {lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K production can occur due to a charmoniumlike resonance (e.g. X(4630) discovered by Belle) with a mass near the {lambda}{sub c}{lambda}{sub c} threshold. Motivated by the BABAR's observation of a resonance in the {lambda}{sub c}K system with a mass of order 2930 MeV, we study in this work the contribution to B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K from the intermediate state {xi}{sub c}(2980) which is postulated to be a first positive-parity excited D-wave charmed baryon state. Assuming that a soft qq quark pair is produced through the {sigma} and {pi} meson exchanges in the configuration for B{yields}{xi}{sub c}(2980){lambda}{sub c} and {lambda}{sub c}{lambda}{sub c}, it is found that branching ratios of B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K and B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -} are of order 3.5x10{sup -4} and 5x10{sup -5}, respectively, in agreement with experiment except that the prediction for the {lambda}{sub c}{lambda}{sub c}K{sup -} is slightly smaller. In conjunction with our previous analysis, we conclude that the enormously large rate of B{yields}{lambda}{sub c}{sup +}{lambda}{sub c}{sup -}K arises from the resonances {xi}{sub c}(2980) and X(4630)

  17. Identification of the Escherichia coli cell division gene sep and organization of the cell division-cell envelope genes in the sep-mur-ftsA-envA cluster as determined with specialized transducing lambda bacteriophages.

    PubMed Central

    Fletcher, G; Irwin, C A; Henson, J M; Fillingim, C; Malone, M M; Walker, J R

    1978-01-01

    From a lysogen with lambda integrated in the leu operon, specialized transducing phages that carry the cell division, murein biosynthesis, and envelope permeability genes located about 0.5 min to the right of leu were isolated. These phages were used to identify the previously undiscovered cell division gene sep. A genetic map proves that sep is located in the sequence leuA sep murE murF murC ddl ftsA envA. A physical map of this region was prepared by heteroduplex analysis of the phage DNAs. Overlapping segments of host DNA extended rightward for as much as 26.4 kilobase pairs from the prophage insertion point (thought to be in leuA) to include all the genes through envA. Images PMID:338600

  18. Longitudinal Polarization of {lambda} and {lambda}-bar Hyperons in Deep-Inelastic Scattering at COMPASS

    SciTech Connect

    Sapozhnikov, M. G.

    2007-06-13

    The longitudinal polarization of {lambda} and {lambda}-bar hyperons produced in deep-inelastic scattering of 160 GeV/c polarized positive muons is studied in the COMPASS (CERN NA58) experiment. Preliminary results on the longitudinal polarization of {lambda} and {lambda}-bar from data collected during the 2003 run are presented.

  19. {lambda}NN Three-Body Force due to Coherent {lambda}-{sigma} Coupling

    SciTech Connect

    Akaishi, Yoshinori; Myint, Khin Swe

    2008-04-29

    The overbinding problem of {sub {lambda}}{sup 5}He is solved by introducing a concept of coherent {lambda}-{sigma} coupling which is equivalent to a {lambda}NN three-body force. This three-body force is coherently enhanced in the 0{sup +} states of {sub {lambda}}{sup 4}H and {sub {lambda}}{sup 4}He. The 0{sup +}-1{sup +} splitting in these hypernuclei is mainly due to coherent {lambda}-{sigma} coupling and partly due to the {lambda}N spin-spin interaction. A {lambda}NN three-body potential is derived from the coupled-channel treatment. The origin of the repulsive and attractive nature of the three-body force is discussed. Coherent {lambda}-{sigma} coupling becomes more important in neutron-rich hypernuclei and especially in neutron-star matter at high densities. The possible existence of ''hyperheavy hydrogen'', {sub {lambda}}{sup 6}H, is suggested.

  20. U Orionis - The evolution and proper motion of the OH maser envelope

    NASA Astrophysics Data System (ADS)

    Chapman, Jessica M.; Cohen, R. J.; Saikia, D. J.

    1991-03-01

    The Jodrell Bank MERLIN array was used to map the OH 1665- and 1667-MHz masers in the circumstellar envelope of U Orionis in 1984, 1986 and 1987. The OH masers lie within a region of extent 130 x 180 sq AU, and have complex distributions which are different for each line and polarization. The masers show clumpy structures with a typical clump size of about 25 AU. The strongest emission is from a ring of radius 60 AU which is interpreted as part of an expanding, tilted torus. The ring has a proper motion of 5.4 + or - 1.4 mas/yr corresponding to a transverse expansion velocity of 7 km/s for the period-luminosity distance to U Orionis of 260 pc. This expansion velocity is also indicated by a compact blueshifted maser spot which lies near the projected stellar position. OH maser emission is also detected from a redshifted filament which appears to project over a considerable radial depth in the envelope and varies in intensity in an erratic fashion.

  1. Study of the Outflow and Disk surrounding a Post-Outburst FU-Orionis Star

    NASA Astrophysics Data System (ADS)

    Mellon, Samuel N.; Perez, L. M.

    2014-01-01

    PP 13 is a fan-shaped cometary nebula located in the constellation of Perseus and embedded in the L1473 dark cloud. At optical wavelengths this region is obscured by the surrounding dark cloud, while at infrared and longer wavelengths two northern objects (PP13Na & PP13Nb) and one southern object (PP13S) are revealed. In the past, the young stellar object inside PP13S, called PP13S*, experienced an FU-Orionis type outburst due to a massive accretion episode and is currently returning to its quiescent state. Studying the FU-Orionis phase is crucial to our understanding of how low mass stars form; it is theorized that all low-mass stars go through this outburst phase while they are forming. I used CARMA 3mm interferometric observations of the PP13 region to study the continuum and molecular line emissions from PP13. With these observations, I determined the source of the previously detected outflow and learned new information about the double star system PP13Na and PP13Nb. Although I was not able to detect the accretion disk in the gas emissions, I plan to use computer modeling to help provide constraints on the properties of PP13S* and its outflow.

  2. Observation of B{sup 0}{yields}{lambda}{lambda}K{sup 0} and B{sup 0}{yields}{lambda}{lambda}K*{sup 0} at Belle

    SciTech Connect

    Chang, Y.-W.; Wang, M.-Z.; Chao, Y.; Hou, W.-S.; Lin, S.-W.; Shiu, J.-G.; Wei, J.-T.; Adachi, I.; Dalseno, J.; Hazumi, M.; Iwasaki, Y.; Kichimi, H.; Nakao, M.; Nishida, S.; Ozaki, H.; Sakai, Y.; Sumisawa, K.; Tanaka, M.; Uehara, S.; Uno, S.

    2009-03-01

    We study the charmless decays B{yields}{lambda}{lambda}h, where h stands for {pi}{sup +}, K{sup +}, K{sup 0},K*{sup +}, or K*{sup 0}, using a 605 fb{sup -1} data sample collected at the {upsilon}(4S) resonance with the Belle detector at the KEKB asymmetric energy e{sup +}e{sup -} collider. We observe B{sup 0}{yields}{lambda}{lambda}K{sup 0} and B{sup 0}{yields}{lambda}{lambda}K*{sup 0} with branching fractions of (4.76{sub -0.68}{sup +0.84}(stat){+-}0.61(syst))x10{sup -6} and (2.46{sub -0.72}{sup +0.87}{+-}0.34)x10{sup -6}, respectively. The significances of these signals in the threshold-mass enhanced mass region, M{sub {lambda}}{sub {lambda}}<2.85 GeV/c{sup 2}, are 12.4{sigma} and 9.3{sigma}, respectively. We also update the branching fraction B(B{sup +}{yields}{lambda}{lambda}K{sup +})=(3.38{sub -0.36}{sup +0.41}{+-}0.41)x10{sup -6} with better accuracy, and report the following measurement or 90% confidence level upper limit in the threshold-mass-enhanced region: B(B{sup +}{yields}{lambda}{lambda}K*{sup +})=(2.19{sub -0.88}{sup +1.13}{+-}0.33)x10{sup -6} with 3.7{sigma} significance; B(B{sup +}{yields}{lambda}{lambda}{pi}{sup +})<0.94x10{sup -6}. A related search for B{sup 0}{yields}{lambda}{lambda}D{sup 0} yields a branching fraction B(B{sup 0}{yields}{lambda}{lambda}D{sup 0})=(1.05{sub -0.44}{sup +0.57}{+-}0.14)x10{sup -5}. This may be compared with the large, {approx}10{sup -4}, branching fraction observed for B{sup 0}{yields}ppD{sup 0}. The M{sub {lambda}}{sub {lambda}} enhancements near threshold and related angular distributions for the observed modes are also reported.

  3. Photoproduction of the Lambda*(1520) Hyperon

    SciTech Connect

    Z. W. Zhao, H. Y. Lu, L. Graham, K. Park, R. W. Gothe

    2010-08-01

    The photoproduction of the Lambda*(1520) on both the proton and neutron have been studied by using the CLAS eg3 run data set. The reactions are gammad-->K+Lambda*(n) and gammad-->K0Lambda*(p) with Lambda*-->pK-. Preliminary total and differential cross sections have been extracted in the photon energy region 1.75 GeVLambda*(1520) on the neutron is reported, and we will extend the results on the proton to higher energies than in previous studies.

  4. Superfluidity of {Lambda} hyperons in neutron stars

    SciTech Connect

    Wang, Y. N.; Shen, H.

    2010-02-15

    We study the {sup 1}S{sub 0} superfluidity of {Lambda} hyperons in neutron star matter and neutron stars. We use the relativistic mean field (RMF) theory to calculate the properties of neutron star matter. In the RMF approach, the meson-hyperon couplings are constrained by reasonable hyperon potentials that include the updated information from recent developments in hypernuclear physics. To examine the {sup 1}S{sub 0} pairing gap of {Lambda} hyperons, we employ several {Lambda}{Lambda} interactions based on the Nijmegen models and used in double-{Lambda} hypernuclei studies. It is found that the maximal pairing gap obtained is a few tenths of a MeV. The magnitude and the density region of the pairing gap are dependent on the {Lambda}{Lambda} interaction and the treatment of neutron star matter. We calculate neutron star properties and find that whether the {sup 1}S{sub 0} superfluidity of {Lambda} hyperons exists in the core of neutron stars mainly depends on the {Lambda}{Lambda} interaction used.

  5. Serologically defined V region subgroups of human lambda light chains.

    PubMed

    Solomon, A; Weiss, D T

    1987-08-01

    The availability of numerous antisera prepared against lambda-type Bence Jones proteins and lambda chains of known amino acid sequence has led to the differentiation and classification of human lambda light chains into one of five V lambda subgroups. The five serologically defined subgroups, V lambda I, V lambda II, V lambda III, V lambda IV, and V lambda VI, correspond to the chemical classification that is based on sequence homologies in the first framework region (FR1). Proteins designated by sequence as lambda V react with specific anti-lambda II antisera and are thus included in the V lambda II subgroup classification. The isotypic nature of the five V lambda subgroups was evidenced through analyses of lambda-type light chains that were isolated from the IgG of normal individuals. Based on analyses of 116 Bence Jones proteins, the frequency of distribution of the lambda I, lambda II/V, lambda III, lambda IV, and lambda VI proteins in the normal lambda chain population is estimated to be 27%, 37%, 23%, 3%, and 10%, respectively. This distribution of V lambda subgroups was comparable to that found among 82 monoclonal Ig lambda proteins. Considerable V lambda intragroup antigenic heterogeneity was also apparent. At least two sub-subgroups were identified among each of the five major V lambda subgroups, implying the existence of multiple genes in the human V lambda genome. The V lambda classification of 54 Ig lambda proteins obtained from patients with primary or multiple myeloma-associated amyloidosis substantiated the preferential association of lambda VI light chains with amyloidosis AL and the predominance of the normally rare V lambda VI subgroup in this disease. PMID:3110284

  6. A spectroscopic survey for lambda Bootis stars. III. Final results

    NASA Astrophysics Data System (ADS)

    Paunzen, E.

    2001-07-01

    In the third paper of a series dedicated to the spectroscopic survey for new lambda Bootis stars, we present all new and confirmed members of the group as well as a detailed analysis of the observed sample. The nature of this small group of chemically peculiar stars of the upper main sequence still challenges our understanding of processes like diffusion, mass-loss and accretion. The typical abundances pattern (nearly solar values for C, N, O and S whereas the Fe-peak elements are moderate to strong underabundant) can still not be explained by any proposed theory. Hence, the significant increase of new members gives the opportunity to investigate the group properties in more detail. We report the discovery of 26 new members of the group and the confirmation of 18 candidates from the literature. This almost triples the number of known lambda Bootis stars. The existence of one member in the young open cluster NGC 2264 and four members in the Orion OB1 association proves that the lambda Bootis phenomenon already works at very early stages of stellar evolution. Recent results from the Hipparcos mission have shown that the well established lambda Bootis stars of the Galactic field comprise the whole area from the Zero Age Main Sequence to the Terminal Age Main Sequence (~ 109 yr for an A-type star). There is a continuous transition between very young and rather evolved evolutionary stages. We find that the overall percentage of lambda Bootis type among all normal type stars in the spectral range from B8 to F4 is 2% in the Galactic field as well as in open clusters. Furthermore, 44 metal-weak objects are listed which might be connected with the lambda Bootis phenomenon. Our biased sample (chosen by photometric boxes) is not distinguished from all A-type stars in the corresponding spectral region by the rotational velocity distribution. Only for the luminosity classes IV and III (especially for the cooler program stars) the determined mean v sin i values are very high

  7. Measurement of the Lambda 0(b) -> Lambda +(c) pi- branching ratio

    SciTech Connect

    Le, Yi; /Johns Hopkins U.

    2003-01-01

    The authors present a measurement of the {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +} {pi}{sup -} branching ratio in p{bar p} collisions at {radical}s = 1.96 TeV using 65 pb{sup -1} data collected by the Collider Detector at Fermilab (CDF). The measurement starts from reconstructing two decay modes: {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}, where {Lambda}{sub c}{sup +} {yields} p K{sup -} {pi}{sup +}; and {bar B}{sup 0} {yields} D{sup +}{pi}{sup -}, where D{sup +} {yields} {pi}{sup +} K{sup -} {pi}{sup +}. The authors obtained 96 {+-} 13 {Lambda}{sub b}{sup 0} and 321 {+-} 22 {bar B}{sup 0} candidates from the CDF Run II Two-Track Hadronic Trigger data sample. The relative branching ratio of the two decays is then measured based on the equation: f{sub {Lambda}{sub b}} BR({Lambda}{sub b} {yields} {Lambda}{sub c}{sup +} {pi}{sup -})/f{sub d} BR({bar B}{sup 0} {yields} D{sup +} {pi}{sup -}) = BR(D{sup +} {yields} K{pi}{pi}) N{sub {Lambda}{sub b}} {epsilon}{sub B{sup 0}}/BR({Lambda}{sub c}{sup +} {yields} pK{pi}) N{sub {bar B}{sup 0}} {epsilon}{sub {Lambda}{sub b}}. The measurement gives f{sub {Lambda}{sub b}} BR({Lambda}{sub b} {yields} {Lambda}{sub c}{sup +}{pi}{sup -})/f{sub d} BR({bar B}{sup 0} {yields} D{sup +}{pi}{sup -}) = 0.66 {+-} 0.11(stat) {+-} 0.09(syst) {+-} 0.18(BR). The {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -} branching ratio is then extracted, giving BR({Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}) = (6.6 {+-} 1.2(stat.) {+-} 0.9(syst.) {+-} 2.3(BR+FR)) x 10{sup -3}. The {Lambda}{sub b}{sup 0} sample they reconstructed in this analysis is the largest fully reconstructed {Lambda}{sub b}{sup 0} sample in existence. The result they report here on the {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -} branching ratio is the world's first such measurement.

  8. High Speed Optical Photometry of V1055 Orionis (=4U 0614+091)

    NASA Astrophysics Data System (ADS)

    Lopez, Isaac; Mason, P. A.; Robinson, E. L.

    2013-01-01

    V1055 Orionis (=4U 0614+091) is thought to be an ultra-compact binary containing a neutron star primary with a white dwarf companion. High-speed (10s) broad-band optical observations using the McDonald Observatory, 2.1m, Otto Struve Telescope were obtained on 13 nights in 2010, 2011, and 2012. The nightly mean brightness remained quite stable over the dataset. The light curve is dominated by complex oscillatory behavior reminiscent of the beating of hidden frequencies. A variety of photometric periods have been previously reported and none are found to be coherent periods in our dataset. Rather, a given night exhibits short lived quasi-periodic variations covering a variety of timescales, especially 10-40 min and even as long as two hours. This short period variability combined with recent spectroscopic abundance studies suggests that the likely donor in this binary is a white dwarf.

  9. DISENTANGLING THE ENVIRONMENT OF THE FU ORIONIS CANDIDATE HBC 722 WITH HERSCHEL

    SciTech Connect

    Green, Joel D.; Evans, Neal J. II; Merello, Manuel; Pooley, David; Kospal, Agnes; Van Kempen, Tim A.; Van Dishoeck, Ewine; Herczeg, Gregory; Quanz, Sascha P.; Henning, Thomas; Bouwman, Jeroen; Lee, Jeong-Eun; Dunham, Michael M.; Meeus, Gwendolyn; Chen, Jo-Hsin; Guedel, Manuel; Skinner, Stephen L.; Rebull, Luisa M.; Guieu, Sylvain

    2011-04-20

    We analyze the submillimeter emission surrounding the new FU Orionis-type object, HBC 722. We present the first epoch of observations of the active environs of HBC 722, with imaging and spectroscopy from PACS, SPIRE, and HIFI on board the Herschel Space Observatory, as well as CO J = 2-1 and 350 {mu}m imaging (SHARC-II) with the Caltech Submillimeter Observatory. The primary source of submillimeter continuum emission in the region-2MASS 20581767+4353310-is located 16'' south-southeast of the optical flaring source while the optical and near-infrared emission is dominated by HBC 722. A bipolar outflow extends over HBC 722; the most likely driver is the submillimeter source. We detect warm (100 K) and hot (246 K) CO emission in the surrounding region, evidence of outflow-driven heating in the vicinity. The region around HBC 722 itself shows little evidence of heating driven by the new outbursting source itself.

  10. Ultraviolet flare on Lambda Andromedae

    NASA Technical Reports Server (NTRS)

    Baliunas, S. L.; Guinan, E. F.; Dupree, A. K.

    1984-01-01

    On November 5, 6, 1982, a luminous, flarelike brightening of the ultraviolet emissions was observed with IUE from the active RS CVn type star Lambda And during the phase of rotation period corresponding to maximum area coverage of the visible hemisphere by starspots and active regions. Enhancements during the flare in the ultraviolet emission lines as large as factors of several and in the ultraviolet continuum up to 80 percent persisted for over 5 hours. The bulk of the radiative output of the flare occurred in Mg II h and k and H I Ly-alpha. Because of the long duration and extreme luminosity of the event, the energy radiated by the flare alone is in excess of 10 to the 35th ergs just in the ultraviolet region. This is the most energetic stellar flare ever recorded in the ultraviolet. In addition, it is the first ultraviolet flare observed from a giant star. In comparison to the largest solar flares, the flare on Lambda And is at least three orders of magnitude more energetic in similar emission lines.

  11. Bacteriophage lambda-based expression vectors.

    PubMed

    Christensen, A C

    2001-03-01

    Bacteriophage lambda has been in use as a cloning vector for over 25 years, and has been used extensively as an expression vector. The efficiency of packaging and infection, and the simplicity of plaque screening are advantages of lambda as a cloning vector. A number of ingenious modifications help overcome the disadvantages associated with its mode of growth and its size. Some lambda vectors have been designed to be readily converted into plasmids or phagemids, and there are a variety of promoters and fusions that can be used to drive expression of foreign genes. Screening lambda libraries with antibodies or ligands is a powerful way of identifying novel genes. PMID:11434310

  12. 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.

  13. Measurement of the forward-backward asymmetry of $$\\Lambda$$ and $$\\bar{\\Lambda}$$ production in $$p \\bar{p}$$ collisions

    DOE PAGESBeta

    Abazov, Victor Mukhamedovich

    2016-02-09

    Here, we studymore » $$\\Lambda$$ and $$\\bar{\\Lambda}$$ production asymmetries in $$p \\bar{p} \\rightarrow \\Lambda (\\bar{\\Lambda}) X$$, $$p \\bar{p} \\rightarrow J/\\psi \\Lambda (\\bar{\\Lambda}) X$$, and $$p \\bar{p} \\rightarrow \\mu^\\pm \\Lambda (\\bar{\\Lambda}) X$$ events recorded by the D0 detector at the Fermilab Tevatron collider at $$\\sqrt{s} = 1.96$$ TeV. We find an excess of $$\\Lambda$$'s ($$\\bar{\\Lambda}$$'s) produced in the proton (antiproton) direction. This forward-backward asymmetry is measured as a function of rapidity. We confirm that the $$\\bar{\\Lambda}/\\Lambda$$ production ratio, measured by several experiments with various targets and a wide range of energies, is a universal function of "rapidity loss", i.e., the rapidity difference of the beam proton and the lambda.« less

  14. Polarization Effects in Lambda and Anti-Lambda Production at HERMES

    SciTech Connect

    Belostotski, S. L.

    2009-08-04

    Study of the LAMBDA and LAMBDA hyperon production in the HERMES experiment is discussed. The data were collected using a 27.6 GeV longitudinally polarized positron (or electron) beam of the HERA accelerator and a polarized or unpolarized target. The transverse polarizations (perpendicular to the production plane) of the LAMBDA and LAMBDA hyperons have been measured. The spin transfer K{sub LL} from the longitudinally polarized target has been found for inclusively detected LAMBDA and LAMBDA events. Longitudinal spin transfer D{sub LL} from the beam to the LAMBDA hyperon in the deep inelastic scattering regime has been analyzed. The D{sub LL} for LAMBDA has been measured for the first time.

  15. Study of Lambda+(c) Cabibbo favored decays containing a Lambda baryon in the final state

    SciTech Connect

    Link, J.M.; Yager, P.M.; Anjos, J.C.; Bediaga, I.; Castromonte, C.; Machado, A.A.; Magnin, J.; Massafferri, A.; de Miranda, J.M.; Pepe, I.M.; Polycarpo, E.; dos Reis, A.C.; Carrillo, S.; Casimiro, E.; Cuautle, E.; Sanchez-Hernandez, A.; Uribe, C.; Vazquez, F.; Agostino, L.; Cinquini, L.; Cumalat, J.P.; /Colorado U. /Fermilab /Frascati /Guanajuato U. /Illinois U., Urbana /Indiana U. /Korea U. /Kyungpook Natl. U. /INFN, Milan /Milan U. /North Carolina U. /Pavia U. /INFN, Pavia /Rio de Janeiro, Pont. U. Catol. /Puerto Rico U., Mayaguez /South Carolina U. /Tennessee U. /Vanderbilt U. /Wisconsin U., Madison

    2005-05-01

    Using data from the FOCUS experiment (FNAL-E831), they study the decay of {Lambda}{sub c}{sup +} baryons into final states contain a {Lambda} hyperon. The branching fractions of {Lambda}{sub c}{sup +} into {Lambda}{pi}{sup +}, {Lambda}{pi}{sup +}{pi}{sup +}{pi}{sup -} and {Lambda}{bar K}{sup 0}K{sup +} relative to that into pK{sup -} {pi}{sup +} are measured to be 0.217 {+-} 0.013 {+-} 0.020, 0.508 {+-} 0.024 {+-} 0.024 and 0.142 {+-} 0.018 {+-} 0.022, respectively. New measurements are also reported. Further, an analysis of the subresonant structure for the {Lambda}{sub c}{sup +} {yields} {Lambda}{pi}{sup +}{pi}{sup +}{pi}{sup -} decay mode is presented.

  16. Transverse polarization of {Lambda} and {bar {Lambda}} hyperons in quasireal photoproduction.

    SciTech Connect

    Airapetian, A.; Akopov, N.; Amarian, M.; Ammosov, V. V.; Andrus, A.; Elalaoui-Moulay, A.; Hafidi, K.; Jackson, H. E.; Potterveld, D. H.; Reimer, P. E.; Sanjiev, I.; Physics; Yerevan Physics Inst.; Inst. Nazionaled di Fisica Nucleare; Inst. High Energy Physics

    2007-11-01

    The HERMES experiment has measured the transverse polarization of Lambda and {ovr Lambda} hyperons produced inclusively in quasireal photoproduction at a positron beam energy of 27.6 GeV. The transverse polarization P{sub n}{sup Lambda} of the Lambda hyperon is found to be positive while the observed {ovr Lambda} polarization is compatible with zero. The values averaged over the kinematic acceptance of HERMES are P{sub n}{sup Lambda} =0.078 {+-} 0.006(stat) {+-} 0.012(syst) and P{sub n}{sup {ovr Lambda}} = -0.025 {+-} 0.015(stat) {+-} 0.018(syst) for Lambda and {ovr Lambda}, respectively. The dependences of P{sub n}{sup Lambda} and P{sub n}{sup {ovr Lambda}} on the fraction zeta of the beam's light-cone momentum carried by the hyperon and on the hyperon's transverse momentum p{sub T} were investigated. The measured Lambda polarization rises linearly with p{sub T} and exhibits a different behavior for low and high values of zeta, which approximately correspond to the backward and forward regions in the center-of-mass frame of the gamma*N reaction.

  17. An X-ray Survey of FU Orionis Stars andUnusual X-ray Emission from Embedded YoungStars in NGC 2071

    NASA Astrophysics Data System (ADS)

    Skinner, Steve L.; Simmons, A. E.; Audard, M.; Briggs, K. R.; Guedel, M.; Meyer, M. R.

    2006-12-01

    We present new results from the first X-ray survey of accreting FU Orionis stars (FUors) and a pointed X-ray observation of the infrared cluster near the reflection nebula NGC 2071 in the Orion B cloud. Both observations reveal unusual X-ray spectra that challenge interpretive models. FUors are low-mass pre-main sequence (PMS) stars that have undergone optical eruptions attributed to a large increase in the disk accretion rate. The prototype FU Ori and V1735 Cyg were both detected and show high temperature plasma typical of magnetic (e.g. coronal) emission. FU Ori also reveals a cooler component at kT = 0.7 keV viewed through lower absorption that could be shock-related, but a magnetic origin seems more likely (Skinner et al. 2006, ApJ, 643, 995). The IR cluster in NGC 2071 is one of the closest star-forming regions known to contain young high-mass stars. We have detected an unusual X-ray source within 1 arcsec of IRS-1, which is thought to be an embedded high-mass star. It drives a powerful outflow and is surrounded by a dense molecular disk or ring. The X-ray spectrum shows a hard continuum extending up to at least 8 keV and a broad fluorescent Fe line at 6.43 keV. The fluorescent line likely originates in cold nearby material (possibly the surrounding disk) illuminated by the heavily-absorbed X-ray source. This work is supported by NASA grants NNG05GJ15G, NNG05GK52G, and NNX06AE93G.

  18. Double Lambda and Xi hypernuclei

    NASA Astrophysics Data System (ADS)

    Nakazawa, Kazuma

    2014-09-01

    Nuclei with double strangeness (S = -2) provide the key information to understand Baryon-Baryon interaction under the SU(3)f symmetry. Therefore we have carried out the experiments at KEK for quarter a century. Recently, the interaction in S = -2 sector is noted to derive the information of the EOS of neutron star. The Lambda-Lambda interaction has been presented to be weak attractive by NAGARA event which showed the production and decay of 6He double-hypernucleus. The event also presented the lower mass limit of H dibaryon. In other five events, we obtained the knowledge about an excitation level of 10Be double-hypernucleus under the consistency with NAGARA event. Moreover, very recently, we have discovered a Xi-14N system which was deeply bound far from the atomic 3D level (0.17 MeV) for a captured Xi hyperon. Since a 8Li nucleus was associated with the decay of one of twin-hypernuclei, the event was uniquely identified as Xi- + 14N ==> 10BeL + 5HeL. The system was selected from 8 million pictures on the test running for development of ``Overall Scanning'' to be used in the coming experiment. This is the first evidence of Xi hypernucleus to be bound and it is impacting for the study of Xi-N interaction. At J-PARC facility, for the further study of hyperon-hyperon interaction, we plan to perform the E07 experiment at J-PARC. In the workshop, we will review the above knowledge obtained by the experiments at KEK-PS, and discuss developed technologies to detected 102 or more double-hypernuclei in the E07 experiment at J-PARC. Nuclei with double strangeness (S = -2) provide the key information to understand Baryon-Baryon interaction under the SU(3)f symmetry. Therefore we have carried out the experiments at KEK for quarter a century. Recently, the interaction in S = -2 sector is noted to derive the information of the EOS of neutron star. The Lambda-Lambda interaction has been presented to be weak attractive by NAGARA event which showed the production and decay of 6He

  19. Recent developments in Lambda networking

    NASA Astrophysics Data System (ADS)

    de Laat, C.; Grosso, P.

    About 6 years ago the first baby-steps were made on opening up dark fiber and DWDM infrastructure for direct use by ISP's after the transformation of the old style Telecom sector into a market driven business. Since then Lambda workshops, community groups like GLIF and a number of experiments have led to many implementations of hybrid national research and education networks and lightpath-based circuit exchanges as pioneered by SURFnet in GigaPort and NetherLight in collaboration with StarLight in Chicago and Canarie in Canada. This article looks back on those developments, describes some current open issues and research developments and proposes a concept of terabit networking.

  20. Alternatives to Goodman and Kruskal's Lambda.

    ERIC Educational Resources Information Center

    Stavig, Gordon R.

    1979-01-01

    Lambda and kappa coefficients of nominal scale association are developed for research hypotheses that involve predictions of modality, agreement, or some theoretically specified configuration. The proposed new coefficient is offered as an alternative to Goodman and Kruskal's lambda. (Author/CTM)

  1. Photoproduction of the {Lambda}*(1520) Hyperon

    SciTech Connect

    Zhao, Z. W.; Lu, H. Y.; Graham, L.; Park, K.; Gothe, R. W.

    2010-08-05

    The photoproduction of the {Lambda}*(1520) on both the proton and neutron have been studied by using the CLAS eg3 run data set. The reactions are {gamma}d{yields}K{sup +{Lambda}}*(n) and {gamma}d{yields}K{sup 0{Lambda}}*(p) with {Lambda}*{yields}pK{sup -}. Preliminary total and differential cross sections have been extracted in the photon energy region 1.75 GeVLambda}*(1520) on the neutron is reported, and we will extend the results on the proton to higher energies than in previous studies.

  2. Bacteriophage Lambda: a Paradigm Revisited ▿

    PubMed Central

    Fogg, Paul C. M.; Allison, Heather E.; Saunders, Jon R.; McCarthy, Alan J.

    2010-01-01

    Bacteriophage lambda has an archetypal immunity system, which prevents the superinfection of its Escherichia coli lysogens. It is now known that superinfection can occur with toxigenic lambda-like phages at a high frequency, and here we demonstrate that the superinfection of a lambda lysogen can lead to the acquisition of additional lambda genomes, which was confirmed by Southern hybridization and quantitative PCR. As many as eight integration events were observed but at a very low frequency (6.4 × 10−4) and always as multiple insertions at the established primary integration site in E. coli. Sequence analysis of the complete immunity region demonstrated that these multiply infected lysogens were not immunity mutants. In conclusion, although lambda superinfection immunity can be confounded, it is a rare event. PMID:20375161

  3. A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, δ Orionis Aa. IV. A Multiwavelength, Non-LTE Spectroscopic Analysis

    NASA Astrophysics Data System (ADS)

    Shenar, T.; Oskinova, L.; Hamann, W.-R.; Corcoran, M. F.; Moffat, A. F. J.; Pablo, H.; Richardson, N. D.; Waldron, W. L.; Huenemoerder, D. P.; Maíz Apellániz, J.; Nichols, J. S.; Todt, H.; Nazé, Y.; Hoffman, J. L.; Pollock, A. M. T.; Negueruela, I.

    2015-08-01

    Eclipsing systems of massive stars allow one to explore the properties of their components in great detail. We perform a multi-wavelength, non-LTE analysis of the three components of the massive multiple system δ Ori A, focusing on the fundamental stellar properties, stellar winds, and X-ray characteristics of the system. The primary’s distance-independent parameters turn out to be characteristic for its spectral type (O9.5 II), but usage of the Hipparcos parallax yields surprisingly low values for the mass, radius, and luminosity. Consistent values follow only if δ Ori lies at about twice the Hipparcos distance, in the vicinity of the σ-Orionis cluster. The primary and tertiary dominate the spectrum and leave the secondary only marginally detectable. We estimate the V-band magnitude difference between primary and secondary to be {{Δ }}V≈ 2\\buildrel{{m}}\\over{.} 8. The inferred parameters suggest that the secondary is an early B-type dwarf (≈B1 V), while the tertiary is an early B-type subgiant (≈B0 IV). We find evidence for rapid turbulent velocities (∼200 km s‑1) and wind inhomogeneities, partially optically thick, in the primary’s wind. The bulk of the X-ray emission likely emerges from the primary’s stellar wind ({log}{L}{{X}}/{L}{Bol}≈ -6.85), initiating close to the stellar surface at {R}0∼ 1.1 {R}*. Accounting for clumping, the mass-loss rate of the primary is found to be {log}\\dot{M}≈ -6.4 ({M}ȯ {{yr}}-1), which agrees with hydrodynamic predictions, and provides a consistent picture along the X-ray, UV, optical, and radio spectral domains.

  4. Bacteriophage lambda: Early pioneer and still relevant.

    PubMed

    Casjens, Sherwood R; Hendrix, Roger W

    2015-05-01

    Molecular genetic research on bacteriophage lambda carried out during its golden age from the mid-1950s to mid-1980s was critically important in the attainment of our current understanding of the sophisticated and complex mechanisms by which the expression of genes is controlled, of DNA virus assembly and of the molecular nature of lysogeny. The development of molecular cloning techniques, ironically instigated largely by phage lambda researchers, allowed many phage workers to switch their efforts to other biological systems. Nonetheless, since that time the ongoing study of lambda and its relatives has continued to give important new insights. In this review we give some relevant early history and describe recent developments in understanding the molecular biology of lambda's life cycle. PMID:25742714

  5. Bacteriophage lambda: early pioneer and still relevant

    PubMed Central

    Casjens, Sherwood R.; Hendrix, Roger W.

    2015-01-01

    Molecular genetic research on bacteriophage lambda carried out during its golden age from the mid 1950's to mid 1980's was critically important in the attainment of our current understanding of the sophisticated and complex mechanisms by which the expression of genes is controlled, of DNA virus assembly and of the molecular nature of lysogeny. The development of molecular cloning techniques, ironically instigated largely by phage lambda researchers, allowed many phage workers to switch their efforts to other biological systems. Nonetheless, since that time the ongoing study of lambda and its relatives have continued to give important new insights. In this review we give some relevant early history and describe recent developments in understanding the molecular biology of lambda's life cycle. PMID:25742714

  6. One milliarcsecond precision studies in the regions of Delta Equulei and Chi(sup 1) Orionis

    NASA Technical Reports Server (NTRS)

    Gatewood, George

    1994-01-01

    Trigonometric parallaxes for stars in the regions of the binary stars Delta Equulei (HR 8123) and Chi(sup l) Orionis (HR 2047) are derived from data collected with the Multichannel Astrometric Photometer (MAP) and the Thaw Refractor of the University of Pittsburgh's Allegheny Observatory. The weighted mean parallax of all trigonometric studies of delta Equ is now +5.42 +/- 0.93 mas, corresponding to absolute magnitudes of 3.87 +/- 0.04 and 3.95 +/- 0.04 mag, respectively, for the primary and secondary. Using the Popper and Dworetsky orbit we find a photocentric semimajor axis of 2.9 +/- 0.8 mas and individual masses of 1.21 +/- 0.090 and 1.19 +/- 0.088 solar masses, respectively, for the primary and secondary components. The weighted mean trigonometric parallax of all studies of the binary star Chi(sup l) Ori is +111.0 +/- 0.92 mas, implying an absolute visual magnitude for the dominant GO V primary of 4.63 +/- 0.018 mag. The photocentric semimajor axis, derived from a fraction of the orbit, is 96.9 +/- 5.4 mas.

  7. One milliarcsecond precision studies in the regions of Delta Equulei and Chi1 Orionis

    NASA Astrophysics Data System (ADS)

    Gatewood, George

    1994-02-01

    Trigonometric parallaxes for stars in the regions of the binary stars Delta Equulei (HR 8123) and Chil Orionis (HR 2047) are derived from data collected with the Multichannel Astrometric Photometer (MAP) and the Thaw Refractor of the University of Pittsburgh's Allegheny Observatory. The weighted mean parallax of all trigonometric studies of delta Equ is now +5.42 +/- 0.93 mas, corresponding to absolute magnitudes of 3.87 +/- 0.04 and 3.95 +/- 0.04 mag, respectively, for the primary and secondary. Using the Popper and Dworetsky orbit we find a photocentric semimajor axis of 2.9 +/- 0.8 mas and individual masses of 1.21 +/- 0.090 and 1.19 +/- 0.088 solar masses, respectively, for the primary and secondary components. The weighted mean trigonometric parallax of all studies of the binary star Chil Ori is +111.0 +/- 0.92 mas, implying an absolute visual magnitude for the dominant GO V primary of 4.63 +/- 0.018 mag. The photocentric semimajor axis, derived from a fraction of the orbit, is 96.9 +/- 5.4 mas.

  8. CONSTRAINING MASS RATIO AND EXTINCTION IN THE FU ORIONIS BINARY SYSTEM WITH INFRARED INTEGRAL FIELD SPECTROSCOPY

    SciTech Connect

    Pueyo, Laurent; Hillenbrand, Lynne; Hinkley, Sasha; Dekany, Richard; Roberts, Jenny; Vasisht, Gautam; Roberts, Lewis C. Jr.; Shao, Mike; Burruss, Rick; Cady, Eric; Oppenheimer, Ben R.; Brenner, Douglas; Zimmerman, Neil; Monnier, John D.; Crepp, Justin; Parry, Ian; Beichman, Charles; Soummer, Remi

    2012-09-20

    We report low-resolution near-infrared spectroscopic observations of the eruptive star FU Orionis using the Integral Field Spectrograph (IFS) Project 1640 installed at the Palomar Hale telescope. This work focuses on elucidating the nature of the faint source, located 0.''5 south of FU Ori, and identified in 2003 as FU Ori S. We first use our observations in conjunction with published data to demonstrate that the two stars are indeed physically associated and form a true binary pair. We then proceed to extract J- and H-band spectro-photometry using the damped LOCI algorithm, a reduction method tailored for high contrast science with IFS. This is the first communication reporting the high accuracy of this technique, pioneered by the Project 1640 team, on a faint astronomical source. We use our low-resolution near-infrared spectrum in conjunction with 10.2 {mu}m interferometric data to constrain the infrared excess of FU Ori S. We then focus on estimating the bulk physical properties of FU Ori S. Our models lead to estimates of an object heavily reddened, A{sub V} = 8-12, with an effective temperature of {approx}4000-6500 K. Finally, we put these results in the context of the FU Ori N-S system and argue that our analysis provides evidence that FU Ori S might be the more massive component of this binary system.

  9. Constraining Mass Ratio and Extinction in the FU Orionis Binary System with Infrared Integral Field Spectroscopy

    NASA Astrophysics Data System (ADS)

    Pueyo, Laurent; Hillenbrand, Lynne; Vasisht, Gautam; Oppenheimer, Ben R.; Monnier, John D.; Hinkley, Sasha; Crepp, Justin; Roberts, Lewis C., Jr.; Brenner, Douglas; Zimmerman, Neil; Parry, Ian; Beichman, Charles; Dekany, Richard; Shao, Mike; Burruss, Rick; Cady, Eric; Roberts, Jenny; Soummer, Rémi

    2012-09-01

    We report low-resolution near-infrared spectroscopic observations of the eruptive star FU Orionis using the Integral Field Spectrograph (IFS) Project 1640 installed at the Palomar Hale telescope. This work focuses on elucidating the nature of the faint source, located 0farcs5 south of FU Ori, and identified in 2003 as FU Ori S. We first use our observations in conjunction with published data to demonstrate that the two stars are indeed physically associated and form a true binary pair. We then proceed to extract J- and H-band spectro-photometry using the damped LOCI algorithm, a reduction method tailored for high contrast science with IFS. This is the first communication reporting the high accuracy of this technique, pioneered by the Project 1640 team, on a faint astronomical source. We use our low-resolution near-infrared spectrum in conjunction with 10.2 μm interferometric data to constrain the infrared excess of FU Ori S. We then focus on estimating the bulk physical properties of FU Ori S. Our models lead to estimates of an object heavily reddened, AV = 8-12, with an effective temperature of ~4000-6500 K. Finally, we put these results in the context of the FU Ori N-S system and argue that our analysis provides evidence that FU Ori S might be the more massive component of this binary system.

  10. Second outburst phase of a young eruptive star V1647 Orionis (McNeil's nebula)

    NASA Astrophysics Data System (ADS)

    Ninan, J. P.; Ojha, D. K.; Mallick, K. K.; Ghosh, S. K.; Joshi, J. S.

    2013-06-01

    Young low mass stars still embedded in dust and molecular gas pass through a stage of outbursts. These outbursts are due to sudden increase in accretion rate from the inner disc. V1647 Orionis underwent an FU Ori kind of outburst in 2004 and returned to its pre-outburst phase in early 2006. Within just 2 years it again underwent a second outburst in 2008; such an event is rarely seen in FU Ori type of outburst. We therefore followed the source in its second outburst phase from 2-m Himalayan Chandra Telescope (HCT) and 2-m IUCAA Girawali Observatory (IGO) Telescope. Our optical and near-infrared (NIR) photometric data show that the source is undergoing a slow but steady dimming of ˜ 0.3 - 0.5 mag since the recent second outburst. It seems that the observed properties of the outburst of V1647 Ori are different from both the EX Ori and FU Ori type of outbursts, and suggest that this star probably represents a new type of eruptive young star, to be different from both FU Ori and EX Ori classes.

  11. Study ofe+e- to Lambda anti-Lambda, Lambda anti-Sigma^0,Sigma^0 anti-Sigma^0 using Initial State Radiation with BaBar

    SciTech Connect

    Aubert, B.

    2007-09-14

    We study the e+e- --> Lambda anti-Lambda gamma, Lambda anti-Sigma0 gamma, Sigma0 anti-Sigma0 gamma processes using 230 fb-1 of integrated luminosity collected by the BaBar detector at e+e- center-of-mass energy of 10.58 GeV. From the analysis of the baryon-antibaryon mass spectra the cross sections for e+e- --> Lambda anti-Lambda, Lambda anti-Sigma0, Sigma0 anti-Sigma0 are measured in the dibaryon mass range from threshold up to 3 GeV/c{sup 2}. The ratio of electric and magnetic form factors, |G{sub E}/G{sub M}|, is measured for e+e- --> Lambda anti-Lambda, and limits on the relative phase between Lambda form factors are obtained. We also measure the J/psi --> Lambda anti-Lambda, Sigma0 anti-Sigma0 and psi(2S) --> Lambda anti-Lambda branching fractions.

  12. The Heavy Mass Expansion lambda(sub)b -> lambda(sub)c Decays

    SciTech Connect

    Mannel, Thomas; Roberts, Winston

    1992-11-01

    We point out that in the decays of the lambda(sub)b to lambda(sub)c one can find predictions which - in the framework of the 1/m(sub)c expansion - do not receive corrections in any order of 1/m(sub)c. We discuss QCD corrections to these predictions and examine some of the consequences for nonleptonic decays.

  13. Measurement of the Production Fraction Times Branching Fraction f(b -> \\Lambda_b) x B(\\Lambda_b -> J/\\psi \\Lambda)

    SciTech Connect

    Heredia-De La Cruz, I.; /CINVESTAV, IPN

    2011-09-01

    A new measurement of the b {yields} {Lambda}{sub b} production fraction multiplied by the {Lambda}{sub b} {yields} J/{psi}{Lambda} branching fraction was performed by the D0 experiment using 6.1 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV. The result of this measurement, f(b {yields} {Lambda}{sub b}) {center_dot} {Beta}({Lambda}{sub b} {yields} J/{psi}{Lambda}) = [6.01 {+-} 0.60 (stat.) {+-} 0.58 (syst.) {+-} 0.28 (PDG)] x 10{sup -5}, represents an improvement in precision by about a factor of three with respect to the current world average. We give an estimate of {Beta}({Lambda}{sub b} {yields} J/{psi}{Lambda}), which takes into account correlations among the different b-hadron production fractions and other weakly decaying baryons.

  14. Nonlinear stability control and lambda-bifurcation

    SciTech Connect

    Erneux, T.; Reiss, E.L.; Magnan, J.F.; Jayakumar, P.K.

    1987-12-01

    Passive techniques for nonlinear stability control are presented for a model of fluidelastic instability. They employ the phenomena of lambda-bifurcation and a generalization of it. lambda-bifurcation occurs when a branch of flutter solutions bifurcates supercritically from a basic solution and terminates with an infinite period orbit at a branch of divergence solutions which bifurcates subcritically from the basic solution. The shape of the bifurcation diagram then resembles the greek letter lambda. When the system parameters are in the range where flutter occurs by lambda-bifurcation, then as the flow velocity increase the flutter amplitude also increases, but the frequencies of the oscillations decrease to zero. This diminishes the damaging effects of structural fatigue by flutter, and permits the flow speed to exceed the critical flutter speed. If generalized lambda-bifurcation occurs, then there is a jump transition from the flutter states to a divergence state with a substantially smaller amplitude, when the flow speed is sufficiently larger than the critical flutter speed.

  15. ELLIPSOIDAL VARIABLE V1197 ORIONIS: ABSOLUTE LIGHT-VELOCITY ANALYSIS FOR KNOWN DISTANCE

    SciTech Connect

    Wilson, R. E.; Chochol, D.; KomzIk, R.; Van Hamme, W.; Pribulla, T.; Volkov, I.

    2009-09-01

    V1197 Orionis light curves from a long-term observing program for red giant binaries show ellipsoidal variation of small amplitude in the V and R{sub C} bands, although not clearly in U and B. Eclipses are not detected. All four bands show large irregular intrinsic variations, including fleeting quasi-periodicities identified by power spectra, that degrade analysis and may be caused by dynamical tides generated by orbital eccentricity. To deal with the absence of eclipses and consequent lack of astrophysical and geometrical information, direct use is made of the Hipparcos parallax distance while the V and R{sub C} light curves and (older) radial velocity curves are analyzed simultaneously in terms of absolute flux. The red giant's temperature is estimated from new spectra. This type of analysis, called Inverse Distance Estimation for brevity, is new and can also be applied to other ellipsoidal variables. Advantages gained by utilization of definite distance and temperature are discussed in regard to how radius, fractional lobe filling, and mass ratio information are expressed in the observations. The advantages were tested in solutions of noisy synthetic data. Also discussed and tested by simulations are ideas on the optimal number of light curves to be solved simultaneously under various conditions. The dim companion has not been observed or discussed in the literature but most solutions find its mass to be well below that of the red giant. Solutions show red giant masses that are too low for evolution to the red giant stage within the age of the Galaxy, although that result is probably an artifact of the intrinsic brightness fluctuations.

  16. CHANDRA REVEALS VARIABLE MULTI-COMPONENT X-RAY EMISSION FROM FU ORIONIS

    SciTech Connect

    Skinner, Stephen L.; Guedel, Manuel; Briggs, Kevin R.; Lamzin, Sergei A.

    2010-10-20

    FU Orionis is the prototype of a class of eruptive young stars ('FUors') characterized by strong optical outbursts. We recently completed an exploratory survey of FUors using XMM-Newton to determine their X-ray properties, about which little was previously known. The prototype FU Ori and V1735 Cyg were detected. The X-ray spectrum of FU Ori was found to be unusual, consisting of a cool moderately absorbed component plus a hotter component viewed through an absorption column density that is an order of magnitude higher. We present here a sensitive (99 ks) follow-up X-ray observation of FU Ori obtained at higher angular resolution with Chandra ACIS-S. The unusual multi-component spectrum is confirmed. The hot component is centered on FU Ori and dominates the emission above 2 keV. It is variable (a signature of magnetic activity) and is probably coronal emission originating close to FU Ori's surface viewed through cool gas in FU Ori's strong wind or accretion stream. In contrast, the X-ray centroid of the soft emission below 2 keV is offset 0.''20 to the southeast of FU Ori, toward the near-IR companion (FU Ori S). This offset amounts to slightly less than half the separation between the two stars. The most likely explanation for the offset is that the companion contributes significantly to the softer X-ray emission below 2 keV (and weakly above 2 keV). The superimposed X-ray contributions from FU Ori and the companion resolve the paradox posed by XMM-Newton of an apparently single X-ray source viewed through two different absorption columns.

  17. Photometric behaviour of the FU Orionis type star, V1057 Cygni, during the last 25 years

    NASA Astrophysics Data System (ADS)

    Kopatskaya, E. N.; Kolotilov, E. A.; Arkharov, A. A.

    2013-09-01

    The FU Orionis type of variable star (FUor), V1057 Cygni, underwent a nova-like outburst in 1969-1970. Among the FUors, V1057 Cyg is notable for having the most dramatic post-maximum decrease in brightness. Thus, photometric monitoring of this object is important for interpretations of the cause of this event. Here, we study the behaviour of V1057 Cyg over the last 25 years on the basis of our optical and infrared observations. The optical and near-infrared observations of V1057 Cyg started in 1974, and we present all our data (up to the end of 2011), including 1085 and 167 nights of optical and infrared photometry, respectively. The UBVRIJHKLM light curves for 1985-2011 show that despite the increased photometric activity, after a rapid decrease in brightness in the mid-1990s, the average level of brightness remained practically constant. After the object becomes fainter than V ≈ 11.5 mag, a swerve appears in the track of the colour-magnitude diagram. The light variability shows a different periodicity in different spectral regions. We have discovered a period of 1631 ± 60 d in the BVR bands (1995-2011) and 523 ± 40 d in the RIJHK bands (2002-2011) with amplitudes of 0.5-0.3 mag. The 523-d period is presumably correlated with the changes in the radial velocity of an emission component in Li I. We conclude that the observed properties of the FUor star V1057 Cyg are in accordance with current models of FUors involving binary or multiple systems.

  18. Spectral energy distribution analysis of class I and class II FU Orionis stars

    SciTech Connect

    Gramajo, Luciana V.; Gómez, Mercedes; Rodón, Javier A. E-mail: mercedes@oac.uncor.edu

    2014-06-01

    FU Orionis stars (FUors) are eruptive pre-main sequence objects thought to represent quasi-periodic or recurring stages of enhanced accretion during the low-mass star-forming process. We characterize the sample of known and candidate FUors in a homogeneous and consistent way, deriving stellar and circumstellar parameters for each object. We emphasize the analysis in those parameters that are supposed to vary during the FUor stage. We modeled the spectral energy distributions of 24 of the 26 currently known FUors, using the radiative transfer code of Whitney et al. We compare our models with those obtained by Robitaille et al. for Taurus class II and I sources in quiescence periods by calculating the cumulative distribution of the different parameters. FUors have more massive disks: we find that ∼80% of the disks in FUors are more massive than any Taurus class II and I sources in the sample. Median values for the disk mass accretion rates are ∼10{sup –7} M {sub ☉} yr{sup –1} versus ∼10{sup –5} M {sub ☉} yr{sup –1} for standard young stellar objects (YSOs) and FUors, respectively. While the distributions of envelope mass accretion rates for class I FUors and standard class I objects are similar, FUors, on average, have higher envelope mass accretion rates than standard class II and class I sources. Most FUors (∼70%) have envelope mass accretion rates above 10{sup –7} M {sub ☉} yr{sup –1}. In contrast, 60% of the classical YSO sample has an accretion rate below this value. Our results support the current scenario in which changes experimented by the circumstellar disk explain the observed properties of these stars. However, the increase in the disk mass accretion rate is smaller than theoretically predicted, although in good agreement with previous determinations.

  19. The FU Orionis Outburst as a Thermal Disk Accretion Event: Detailed Calculations and Comparison to Observations

    NASA Technical Reports Server (NTRS)

    Bell, K. R.

    1994-01-01

    FU Orionis outbursts are temporary large increases in luminosity: x(40-250) thought to occur repeatedly in all low mass young stellar systems. We discuss detailed calculations of viscous accretion disks suggesting that FU Ori events signify the existence of a protostellar disk transporting mass at a rate of (1-10) x 10(exp -6) Solar Mass/yr, in agreement with theoretical and observational estimates of molecular cloud core collapse rates. Accretion through the inner edge of disks subject to outburst is self-regulated through the thermal ionization instability such that long periods (approximately 1000 yrs) of low mass flux: (1-10) x 10(exp -8) Solar Mass/yr, are punctuated by short periods (approximately 100 yrs) of high mass flux: (1-10) x 10(exp -5) Solar Mass/yr. The unstable region of the disk extends radially only to a distance of approximately 1/4 AU. Beyond this region matter is transported stably at the infall rate. In systems for which M = 1 Solar Mass, with an inner disk edge of 3 Solar Radius, the critical rate for outbursts is 5 x 10(exp -7) Solar Mass/yr independent of the magnitude of the viscous alpha parameter consistent with estimates of boundary layer mass flux in T Tauri stars. We use timescales of observed outbursts to constrain the magnitude of the alpha parameter to be 10(exp -4) where hydrogen is neutral and 10(exp -3) where ionized. Light curves of V1515 Cyg, FU Ori, and V1057 Cyg are reproduced; the latter two require application of a small perturbation in surface density to produce observed rapid rise times. Detailed reply is made to objections to the accretion disk model for outbursts. Comparison to observations are made of time dependent spectral energy distributions, colors, and line-width velocity evolution.

  20. The FU Orionis Outburst as a Thermal Disk Accretion Event: Detailed Calculations and Comparison to Observations

    NASA Technical Reports Server (NTRS)

    Bell, K. R.; Cuzzi, Jeff (Technical Monitor)

    1994-01-01

    FU Orionis outbursts are temporary large increases in luminosity: x (40 - 250) thought to occur repeatedly in all low mass young stellar systems. We discuss detailed calculations of viscous accretion disks suggesting that FU Ori events signify the existence of a protostellar disk transporting mass at a rate of (1 - 10) x 10(exp 6) solar mass / yr, in agreement with theoretical and observational estimates of molecular cloud core collapse rates. Accretion through the inner edge of disks subject to outburst is self-regulated through the thermal ionization instability such that long periods (approx. 1000 yrs) of low mass flux: (1 - 10) x 10(exp -5) solar mass / yr, are punctuated by short periods (approx. 100 yrs) of high mass flux: (1-10) x 10(exp -5) solar mass / yr. The unstable region of the disk extends radially only to a distance of approx. = 1/4 AU. Beyond this region matter is transported stably at the infall rate. In systems for which M(sum *) = 1 solar mass with an inner disk edge of 3 solar radius, the critical rate for outbursts is 5 x 10(exp -7) solar mass / yr independent of the magnitude of the viscous ce parameter consistent with estimates of boundary layer mass flux in T Tauri stars. We use timescales of observed outbursts to constrain the magnitude of the alpha parameter to be 10(exp -4) where hydrogen is neutral and 10(exp -3) where ionized. Light curves of V1515 Cyg, FU Ori, and V1057 Cya are reproduced; the latter two require application of a small perturbation in surface density to produce observed rapid rise times. Detailed reply is made to objections to the accretion disk model for outbursts. Comparison to observations are made of time dependent spectral energy distributions, colors, and line-width velocity evolution.

  1. Does lambda sub 2,2 vary?

    NASA Technical Reports Server (NTRS)

    Wagner, C. A.

    1971-01-01

    An attempt has been made to find a secular drift in lambda sub 2,2, or the phase of the low order and degree portion of the geogravity field. This portion may be associated with mass anomalies near the core-mantle boundary. From the geomagnetic evidence, such anomalies might have westward drifts on the order of 0.5 degrees/year. Tracking data on 8 synchronous satellite over a period of 6 years were examined for residual accelerations which might be explained by a drift of the lambda sub 2,2 gravity phase angle. No conclusive movement of lambda sub 2,2 was detected. But a measured upper bound on the drift of less than 0.05 degrees/year is still compatible with possible slow moving irregularities in the region of the core-mantle boundary.

  2. {lambda}(1405)-induced nonmesonic decay in kaonic nuclei

    SciTech Connect

    Sekihara, T.; Jido, D.; Kanada-En'yo, Y.

    2009-06-15

    Nonmesonic decay of kaonic nuclei is investigated under a {lambda}(1405) doorway picture in which the K absorptions in nuclei take place through the {lambda}(1405) resonance. Calculating {lambda}(1405)N{yields}YN transitions with one-meson exchange, we find that the nonmesonic decay ratio {gamma}{sub {lambda}}{sub N}/{gamma}{sub {sigma}{sup 0}}{sub N} depends strongly on the ratio of the couplings {lambda}(1405)-KN and {lambda}(1405)-{pi}{sigma}. Especially, a larger {lambda}(1405)-KN coupling leads to enhancement of the decay to {lambda}N. Using the chiral unitary approach for description of the KN amplitudes, we obtain {gamma}{sub {lambda}}{sub N}/{gamma}{sub {sigma}{sup 0}}{sub N}{approx_equal}1.2 almost independently of the nucleon density and find the total nonmesonic decay width calculated in uniform nuclear matter to be 22 MeV at the normal density.

  3. Very low-luminosity Class I/Flat outflow sources in sigma Orionis: Clues to alternative formation mechanisms for very low-mass stars

    NASA Astrophysics Data System (ADS)

    Riaz, Basmah; Whelan, E.; Thompson, M.; Vorobyov, E.; Lodieu, N.

    2015-01-01

    We present an optical through sub-millimetre multi-wavelength study of two very low-luminosity Class I/Flat systems, Mayrit 1701117 and Mayrit 1082188, in the sigma Orionis cluster. We performed moderate resolution (R 1000) optical ( 0.4-0.9mu) spectroscopy with the TWIN spectrograph at the Calar Alto 3.5-m telescope. The spectra for both sources show prominent emission in accretion- and outflow-associated lines. The mean accretion rate measured from multiple line diagnostics is 6.4x10^{-10} Msun/yr for Mayrit 1701117, and 2.5x10^{-10} Msun/yr for Mayrit 1082188. The outflow mass loss rates for the two systems are similar and estimated to be 1x10^{-9} Msun/yr. The activity rates are within the range observed for low-mass Class I protostars. We obtained sub-millimetre continuum observations with the Submillimetre Common-User Bolometer Array (SCUBA-2) bolometer at the James Clerk Maxwell Telescope. Both objects are detected at a >5-sigma level in the SCUBA-2 850mu band. The bolometric luminosity of the targets as measured from the observed spectral energy distribution over 0.8-850mu is 0.18+/-0.04 Lsun for Mayrit 1701117, and 0.16+/-0.03 Lsun for Mayrit 1082188, and is in the very low-mass range. The total dust+gas mass derived from sub-millimetre fluxes is 36 M_Jup and 22 M_Jup for Mayrit 1701117 and Mayrit 1082188, respectively. There is the possibility that some of the envelope material might be dissipated by the strong outflows driven by these sources, resulting in a final mass of the system close to or below the sub-stellar limit. Given the membership of these objects in a relatively evolved cluster of 3 Myr of age, we consider an alternate formation mechanism in the context of the `hybrid' model of disk fragmentation, followed by ejection of a gaseous clump.

  4. Lambda Station: On-demand flow based routing for data intensive Grid applications over multitopology networks

    SciTech Connect

    Bobyshev, A.; Crawford, M.; DeMar, P.; Grigaliunas, V.; Grigoriev, M.; Moibenko, A.; Petravick, D.; Rechenmacher, R.; Newman, H.; Bunn, J.; Van Lingen, F.; Nae, D.; Ravot, S.; Steenberg, C.; Su, X.; Thomas, M.; Xia, Y.; /Caltech

    2006-08-01

    Lambda Station is an ongoing project of Fermi National Accelerator Laboratory and the California Institute of Technology. The goal of this project is to design, develop and deploy network services for path selection, admission control and flow based forwarding of traffic among data-intensive Grid applications such as are used in High Energy Physics and other communities. Lambda Station deals with the last-mile problem in local area networks, connecting production clusters through a rich array of wide area networks. Selective forwarding of traffic is controlled dynamically at the demand of applications. This paper introduces the motivation of this project, design principles and current status. Integration of Lambda Station client API with the essential Grid middleware such as the dCache/SRM Storage Resource Manager is also described. Finally, the results of applying Lambda Station services to development and production clusters at Fermilab and Caltech over advanced networks such as DOE's UltraScience Net and NSF's UltraLight is covered.

  5. Hypertriton and light nuclei production at Lambda-production subthreshold energy in heavy-ion collisions

    SciTech Connect

    Zhang, S.; Zu, Z.; Chen, J.H., Ma, Y.G., Cai, X-Z, Ma, G.L., Zhong, C.

    2011-08-01

    High-energy heavy-ion collisions produce abundant hyperons and nucleons. A dynamical coalescence model coupled with the ART model is employed to study the production probabilities of light clusters, deuteron (d), triton (t), helion ({sup 3}He), and hypertriton ({sub {Lambda}}{sup 3}H) at subthreshold energy of Aproduction ({approx} 1 GeV per nucleon). We study the dependence on the reaction system size of the coalescence penalty factor per additional nucleon and entropy per nucleon. The Strangeness Population Factor (S{sub 3} = {sup 3}{sub {Lambda}}H/({sup 3}He x {Lambda}/p)) shows an extra suppression of hypertriton comparing to light clusters of the same mass number. This model predicts a hypertriton production cross-section of a few {mu}b in {sup 36}Ar+{sup 36}Ar, {sup 40}Ca+{sup 40}Ca and {sup 56}Ni+{sup 56}Ni in 1 A GeV reactions. The production rate is as high as a few hypertritons per million collisions, which shows that the fixed-target heavy-ion collisions at CSR (Lanzhou/China) at {Lambda} subthreshold energy are suitable for breaking new ground in hypernuclear physics.

  6. Associated {Lambda} production at Jefferson Lab

    SciTech Connect

    Niculescu, G.; Baker, O.K. |; Avery, S.; E93018 Collaboration

    1997-12-31

    The {sup 1}H(e, e{prime}K{sup +}){Lambda} and {sup 1}H(e, e{prime}K{sup +}){Sigma}{sup 0} reactions were studied as a function of the squared four-momentum-transfer, Q{sup 2}, and the virtual photon polarization, {var_epsilon}, thus enabling the separation of the longitudinal and transverse parts of the cross section. The existence of a sensibly large longitudinal component for the {sup 1}H(e, e{prime}K{sup +}){Lambda} reaction seems to be sustained by these data.

  7. Lambda Exonuclease Digestion of CGG Trinucleotide Repeats

    PubMed Central

    Conroy, R.S.; Koretsky, A.P.; Moreland, J.

    2011-01-01

    Fragile X syndrome and other triplet repeat diseases are characterized by an elongation of a repeating DNA triplet. The ensemble-averaged lambda exonuclease digestion rate of different substrates, including one with an elongated FMR1 gene containing 120 CGG repeats, was measured using absorption and fluorescence spectroscopy. Using magnetic tweezers sequence-dependent digestion rates and pausing was measured for individual lambda exonucleases. Within the triplet repeats a lower average and narrower distribution of rates and a higher frequency of pausing was observed. PMID:19562332

  8. GALAXY CLUSTER BULK FLOWS AND COLLISION VELOCITIES IN QUMOND

    SciTech Connect

    Katz, Harley; McGaugh, Stacy; Teuben, Peter; Angus, G. W. E-mail: stacy.mcgaugh@case.edu E-mail: angus.gz@gmail.com

    2013-07-20

    We examine the formation of clusters of galaxies in numerical simulations of a QUMOND cosmogony with massive sterile neutrinos. Clusters formed in these exploratory simulations develop higher velocities than those found in {Lambda}CDM simulations. The bulk motions of clusters attain {approx}1000 km s{sup -1} by low redshift, comparable to observations whereas {Lambda}CDM simulated clusters tend to fall short. Similarly, high pairwise velocities are common in cluster-cluster collisions like the Bullet Cluster. There is also a propensity for the most massive clusters to be larger in QUMOND and to appear earlier than in {Lambda}CDM, potentially providing an explanation for ''pink elephants'' like El Gordo. However, it is not obvious that the cluster mass function can be recovered.

  9. Behavior of Coliphage Lambda in Shigella flexneri 2a

    PubMed Central

    Gemski, P.; Alexeichik, J. A.; Baron, L. S.

    1972-01-01

    The insensitivity of wild-type Shigella flexneri 2a to coliphage λ is a consequence of its native genetic defect in the malA gene cluster. The “smooth” S. flexneri 2a lipopolysaccharide layer affects the efficient adsorption of λ. Derivatives, capable of serving as functional hosts for λ, were obtained by repairing the malA lesion, enabling the expression of the malB-λrcp region of S. flexneri. Introduction of a mutation into S. flexneri causing a “rough” lipopolysaccharide character resulted in more efficient adsorption of λ. Such S. flexneri hosts can be stably lysogenized and upon induction yield gal+-transducing lysates. Lambda propagated on a malA+ rough S. flexneri host was restricted by Escherichia coli K-12 and E. coli B, but not by E. coli C. This S. flexneri host did not restrict λ grown on these E. coli strains. PMID:4563593

  10. Small-Scale Power Spectrum and Correlations in Lambda + Cold Dark Matter Models

    NASA Astrophysics Data System (ADS)

    Klypin, Anatoly; Primack, Joel; Holtzman, Jon

    1996-07-01

    Cosmological models with a positive cosmological constant ({LAMBDA} > 0) and {OMEGA}_0_ < 1 have a number of attractive features. A larger Hubble constant H_0_, which can be compatible with the recent Hubble Space Telescope (HST) estimate, and a large fraction of baryon density in galaxy clusters make them current favorites. Early galaxy formation also is considered as a welcome feature of these models. But early galaxy formation implies that fluctuations on scales of a few megaparsecs spent more time in the nonlinear regime, as compared With standard cold dark matter (CDM) or cold + hot dark matter (CHDM) models. As has been known for a long time, this results in excessive clustering on small scales. We show that a typical {LAMBDA}CDM model with H_0_ = 70 km s^-1^ Mpc^-1^, {OMEGA}_0_ = 0.3, and cosmological constant {LAMBDA} such that {OMEGA}LAMBDA_ = {LAMBDA}/(3H_0_^2^) = 1 - {OMEGA}_0_, normalized to COBE on large scales and compatible with the number density of galaxy clusters, predicts a power spectrum of galaxy clustering in real space which is too high: at least twice larger than CfA estimates and 3 times larger than estimates for the APM Galaxy Survey for wavenumbers k = (0.4- 1)h Mpc^-1^. This conclusion holds if we assume either that galaxies trace the dark matter (σ_8_ ~ 1.1 for this model) or just that a region with higher density produces more galaxies than a region with lower density. The only way to reconcile the model with the observed power spectrum P(k) is to assume that regions with high dark matter density produce fewer galaxies than regions with low density. Theoretically this is possible, but it seems very unlikely: X-ray emission from groups and clusters indicates that places with a large density of dark matter produce a large number of galaxies. Since it follows that the low-{OMEGA} {LAMBDA}CDM models are in serious trouble, we discuss which ACDM models have the best hope of surviving the confrontation with all available observational data.

  11. The Lambda Point Experiment in Microgravity

    NASA Technical Reports Server (NTRS)

    Lipa, J. A.; Swanson, D. R.; Nissen, J. A.; Chui, T. C. P.

    1993-01-01

    In October 1992 a low temperature experiment was flown on the Space Shuttle in low earth orbit, using the JPL low temperature research facility. The objective of the mission was to measure the heat capacity and thermal relaxation of helium very close to the lambda point with the smearing effect of gravity removed.

  12. {lambda}{sub b}{yields}p, {lambda} transition form factors from QCD light-cone sum rules

    SciTech Connect

    Wang Yuming; Lue Caidian; Shen Yuelong

    2009-10-01

    Light-cone sum rules for the {lambda}{sub b}{yields}p, {lambda} transition form factors are derived from the correlation functions expanded by the twist of the distribution amplitudes of the {lambda}{sub b} baryon. In terms of the {lambda}{sub b} three-quark distribution amplitude models constrained by the QCD theory, we calculate the form factors at small momentum transfers and compare the results with those estimated in the conventional light-cone sum rules (LCSR) and perturbative QCD approaches. Our results indicate that the two different versions of sum rules can lead to the consistent numbers of form factors responsible for {lambda}{sub b}{yields}p transition. The {lambda}{sub b}{yields}{lambda} transition form factors from LCSR with the asymptotic {lambda} baryon distribution amplitudes are found to be almost 1 order larger than those obtained in the {lambda}{sub b}-baryon LCSR, implying that the preasymptotic corrections to the baryonic distribution amplitudes are of great importance. Moreover, the SU(3) symmetry breaking effects between the form factors f{sub 1}{sup {lambda}{sub b}}{sup {yields}}{sup p} and f{sub 1}{sup {lambda}{sub b}}{sup {yields}}{sup {lambda}} are computed as 28{sub -8}{sup +14}% in the framework of {lambda}{sub b}-baryon LCSR.

  13. Submillimeter Continuum Observations of the T Tauri Spectroscopic Binary GW Orionis

    NASA Astrophysics Data System (ADS)

    Mathieu, R. D.; Adams, F. C.; Fuller, G. A.; Jensen, E. L.

    1993-05-01

    We have used the James Clerk Maxwell Telescope to detect strong submillimeter (350 microns - 1100 microns) continuum emission from the classical T Tauri star GW Orionis. GW Ori is a spectroscopic binary with a period of 242 days and a separation of 1 AU (Mathieu, Adams and Latham, 1991, AJ 101, 2184; MAL). It is the first pre-main sequence short-period binary system to show submillimeter emission. The submillimeter luminosity is comparable to the largest among both T Tauri and Herbig Ae stars. The emission is confined within a radius of 5 arcsec (2000 AU). We show that the origin of the emission must be circumbinary. With an optically thin, isothermal approximation we place a lower limit of 0.1 M_⊙ on the mass of circumbinary material, assuming a maximum temperature of 150 K. Using the pure-disk models of MAL, we find disk masses between a few tenths of a solar mass and a few solar masses, depending on choice of submillimeter opacity. These values are a significant fraction of the total stellar mass (2.8 M_⊙ to 3.8 M_⊙, depending on inclination) and possibly comparable to the secondary mass alone (0.3 M_⊙ to 1.3 M_⊙). Our fluxes are inconsistent with the disk-envelope model of MAL, for typically adopted opacities. Other extended distributions of material need to be considered, particularly since GW Ori lies near the birthline. If the circumbinary material is in a disk, then the derived masses are sufficient to drive rapid evolution of the binary orbital elements, including exciting eccentricity into the orbit. As such, the low eccentricity of GW Ori (e=0.04+/-0.06) may indicate that the disk matter does not populate the strong resonances near the secondary. In addition, the case of GW Ori suggests that massive circumbinary disks can survive the binary formation process, placing constraints on the degree of disk consumption and/or replenishment (e.g., if formation is the result of disk instabilities) or circuminary disk disruption (e.g.,in a disk

  14. Dynamical mass of the O-type supergiant in ζ Orionis A

    NASA Astrophysics Data System (ADS)

    Hummel, C. A.; Rivinius, Th.; Nieva, M.-F.; Stahl, O.; van Belle, G.; Zavala, R. T.

    2013-06-01

    Aims: A close companion of ζ Orionis A was found in 2000 with the Navy Precision Optical Interferometer (NPOI), and shown to be a physical companion. Because the primary is a supergiant of type O, for which dynamical mass measurements are very rare, the companion was observed with NPOI over the full 7-year orbit. Our aim was to determine the dynamical mass of a supergiant that, due to the physical separation of more than 10 AU between the components, cannot have undergone mass exchange with the companion. Methods: The interferometric observations allow measuring the relative positions of the binary components and their relative brightness. The data collected over the full orbital period allows all seven orbital elements to be determined. In addition to the interferometric observations, we analyzed archival spectra obtained at the Calar Alto, Haute Provence, Cerro Armazones, and La Silla observatories, as well as new spectra obtained at the VLT on Cerro Paranal. In the high-resolution spectra we identified a few lines that can be associated exclusively to one or the other component for the measurement of the radial velocities of both. The combination of astrometry and spectroscopy then yields the stellar masses and the distance to the binary star. Results: The resulting masses for components Aa of 14.0 ± 2.2 M⊙ and Ab of 7.4 ± 1.1 M⊙ are low compared to theoretical expectations, with a distance of 294 ± 21 pc which is smaller than a photometric distance estimate of 387 ± 54 pc based on the spectral type B0III of the B component. If the latter (because it is also consistent with the distance to the Orion OB1 association) is adopted, the mass of the secondary component Ab of 14 ± 3 M⊙ would agree with classifying a star of type B0.5IV. It is fainter than the primary by about 2.2 ± 0.1 magnitudes in the visual. The primary mass is then determined to be 33 ± 10 M⊙. The possible reasons for the distance discrepancy are most likely related to physical

  15. The weak magnetic field of the O9.7 supergiant ζOrionisA

    NASA Astrophysics Data System (ADS)

    Bouret, J.-C.; Donati, J.-F.; Martins, F.; Escolano, C.; Marcolino, W.; Lanz, T.; Howarth, I. D.

    2008-09-01

    We report here the detection of a weak magnetic field of 50-100G on the O9.7 supergiant ζOrionisA (ζOriA), using spectropolarimetric observations obtained with NARVAL at the 2-m Télescope Bernard Lyot atop Pic du Midi (France). ζOriA is the third O star known to host a magnetic field (along with θ1OriC and HD191612), and the first detection on a `normal' rapidly rotating O star. The magnetic field of ζOriA is the weakest magnetic field ever detected on a massive star. The measured field is lower than the thermal equipartition limit (about 100G). By fitting non-local thermodynamic equilibrium (NLTE) model atmospheres to our spectra, we determined that ζOriA is a 40Msolar star with a radius of 25Rsolar and an age of about 5-6Myr, showing no surface nitrogen enhancement and losing mass at a rate of about 2 × 10-6Msolaryr-1. The magnetic topology of ζOriA is apparently more complex than a dipole and involves two main magnetic polarities located on both sides of the same hemisphere; our data also suggest that ζOriA rotates in about 7.0d and is about 40° away from pole-on to an Earth-based observer. Despite its weakness, the detected magnetic field significantly affects the wind structure; the corresponding Alfvén radius is however very close to the surface, thus generating a different rotational modulation in wind lines than that reported on the two other known magnetic O stars. The rapid rotation of ζOriA with respect to θ1OriC appears as a surprise, both stars having similar unsigned magnetic fluxes (once rescaled to the same radius); it may suggest that the subequipartition field detected on ζOriA is not a fossil remnant (as opposed to that of θ1 OriC and HD191612), but the result of an exotic dynamo action produced through magnetohydrodynamics (MHD) instabilities. Based on observations obtained at the Télescope Bernard Lyot (TBL), operated by the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique of France

  16. Post-outburst phase of McNeil's nebula (V1647 Orionis)

    NASA Astrophysics Data System (ADS)

    Ojha, D. K.; Ghosh, S. K.; Tej, A.; Verma, R. P.; Vig, S.; Anupama, G. C.; Sahu, D. K.; Parihar, P.; Bhatt, B. C.; Prabhu, T. P.; Maheswar, G.; Bhatt, H. C.; Anandarao, B. G.; Venkataraman, V.

    2006-05-01

    We present a detailed study of the post-outburst phase of McNeil's nebula (V1647 Orionis) using optical B, V, R, I and near-infrared (NIR) J, H, K photometric and low-resolution optical spectroscopic observations. The observations were carried out with the Himalaya Faint Object Spectrograph Camera (HFOSC), NIR camera (NIRCAM), the Tata Institute of Fundamental Research (TIFR) Near-Infrared Camera (TIRCAM) and NICMOS cameras on the 2-m Himalayan Chandra Telescope (HCT) and 1.2-m Physical Research Laboratory (PRL) telescopes during the period 2004 February-2005 December. The optical and NIR observations show a general decline in the brightness of the exciting source of McNeil's nebula (V1647 Ori). Our recent optical images show that V1647 Ori has faded by more than 3 mag since February 2004. McNeil's nebula has also faded considerably. The optical/NIR photometric data also show a significant variation in the magnitudes (ΔV= 0.78, ΔR= 0.44, ΔI= 0.21, ΔJ= 0.24 and ΔH= 0.20 mag) of V1647 Ori within a period of one month, which is possibly undergoing a phase similar to eruptive variables, like EXors or FUors. The optical spectra show a few features such as strong Hα emission with blue-shifted absorption and the CaII IR triplet (8498, 8542 and 8662 Å) in emission. As compared to the period just after outburst, there is a decrease in the depth and extent of the blue-shifted absorption component, indicating a weakening in the powerful stellar wind. The presence of the CaII IR triplet in emission confirms that V1647 Ori is a pre-main-sequence star. The long-term, post-outburst photometric observations of V1647 Ori suggest an EXor rather than an FUor event. An optical/IR comparison of the region surrounding McNeil's nebula shows that the optical nebula is more widely and predominantly extended to the north, whereas the IR nebula is relatively confined (diameter ~60 arcsec), but definitely extended, to the south, too. The large colour gradient from north to south and

  17. A Revised Geometry for the Magnetic Wind of θ1 Orionis C

    NASA Astrophysics Data System (ADS)

    Smith, Myron A.; Fullerton, Alex W.

    2005-01-01

    The star θ1 Orionis C (O6-7 V) is often cited as a hot analog of Bp variables, because its optical and UV line and X-ray continuum fluxes modulate over the magnetic/rotational period. In this circumstance, one expects emission and absorption components of the UV resonance lines to vary as a flattened magnetosphere corotates with the star. In this paper, we reexamine the detailed velocity behavior of several strong UV lines. Whereas past work has focused on variations of the full profiles, we find that the blue and red wings of the C IV and N V resonance lines exhibit anticorrelated modulations. These appear as absorption excesses at large blueshifts and as flux elevations at moderate redshifts at the edge-on phase φ=0.5. No rest-frame absorption features, which are the typical signatures of cool, static disks surrounding Bp stars, can be detected at any phase. We suggest that this behavior is caused by two geometrically distinct components of the wind, which are defined by the relationship between the extent of a magnetic loop and the local Alfvén radius. Streams on field lines opening outside this radius are first channeled toward the magnetic equator, but after reaching the Alfven radius, they are forced outward by radiative forces, eventually to become an expanding radial outflow. This wind component causes blueshifted absorption as the corotating magnetic equatorial plane crosses the observer's line of sight (φ=0.5). The geometry of the inner component requires a more complicated interpretation. Wind streams first follow closed loops and collide at the magnetic equator with counterpart streams from the opposite pole. There they coalesce and fall back to the star along their original field lines. The high temperatures in these falling condensations cause the redshifted emission. The rapid circulation of these flows is likely the reason for the absence of signatures of a cool disk (e.g., zero-velocity absorptions at φ~0.5) in the strong UV lines.

  18. The Hyperon {Lambda}(1405) in p+p reactions

    SciTech Connect

    Siebenson, Johannes

    2011-10-21

    We present an analysis of the hyperon {Lambda}(1405) for p+p reactions at 3.5 GeV kinetic beam energy. The data were taken with the High Acceptance Di-Electron Spectrometer (HADES). A {Lambda}(1405) signal could be reconstructed in both charged decay channels ({Lambda}(1405){yields}{Sigma}{sup {+-}}{pi}{sup {+-}}).

  19. Measurement of the Branching Fraction and Lambda-bar Polarization in B0 -> Lambda-par p pi-

    SciTech Connect

    Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D.N.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Osipenkov, I.L.; /LBL, Berkeley /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, San Diego /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /Harvard U. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa U. /Iowa State U. /Johns Hopkins U. /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT, LNS /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /Mt. Holyoke Coll. /INFN, Naples /Naples U. /INFN, Naples /INFN, Naples /Naples U. /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /Pennsylvania U. /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas U. /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U., IFIC /Victoria U. /Warwick U. /Wisconsin U., Madison

    2009-08-03

    We present a measurement of the B{sup 0} {yields} {bar {Lambda}}p{pi}{sup -} branching fraction performed using the BABAR detector at the PEP-II asymmetric e{sup +}e{sup -} collider. Based on a sample of 467 x 10{sup 6} B{bar B} pairs we measure {Beta}(B{sup 0} {yields} {bar {Lambda}}p{pi}{sup -}) [3.07 {+-} 0.31(stat.) {+-} 0.23(syst.)] x 10{sup -6}. The measured differential spectrum as a function of the dibaryon invariant mass m({bar {Lambda}}p) shows a near-threshold enhancement similar to that observed in other baryonic B decays. We study the {bar {Lambda}} polarization as a function of {bar {Lambda}} energy in the B{sup 0} rest frame (E*{sub {bar {Lambda}}}) and compare it with theoretical expectations of fully longitudinally right-polarized {bar {Lambda}} at large E*{sub {bar {Lambda}}}.

  20. Study of the decay asymmetry parameter and CP violation parameter in the Lambda(c)+ ---> Lambda pi+ decay

    SciTech Connect

    Link, J.M.; Yager, P.M.; Anjos, J.C.; Bediaga, I.; Castromonte, C.; Machado, A.A.; Magnin, J.; Massafferri, A.; de Miranda, J.M.; Pepe, I.M.; Polycarpo, E.; dos Reis, A.C.; Carrillo, S.; Casimiro, E.; Cuautle, E.; Sanchez-Hernandez, A.; Uribe, C.; Vazquez, F.; Agostino, L.; Cinquini, L.; Cumalat, J.P.; /Colorado U. /Fermilab /Frascati /Guanajuato U. /Illinois U., Urbana /Indiana U. /Korea U. /Kyungpook Natl. U. /INFN, Milan /Milan U. /North Carolina U. /Pavia U. /INFN, Pavia /Rio de Janeiro, Pont. U. Catol. /Puerto Rico U., Mayaguez /South Carolina U. /Tennessee U. /Vanderbilt U. /Wisconsin U., Madison

    2005-09-01

    Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter a{sub {Lambda}{sub c}} in {Lambda}{sub c}{sup +} {yields} {Lambda}{pi}{sup +} decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter {Alpha} {triple_bond} a{sub {Lambda}{sub c}} + a{sub {ovr {Lambda}{sub c}}}/a{sub {Lambda}{sub c}} - a{sub {ovr {Lambda}{sub c}}}. We obtain a{sub {Lambda}{sub c}} = -0.78 {+-} 0.16 {+-} 0.13 and {Alpha} = -0.07 {+-} 0.19 {+-} 0.12 where errors are statistical and systematic.

  1. Detection of O I and Si II far-infrared fine-structure emission from Alpha Orionis

    NASA Technical Reports Server (NTRS)

    Haas, Michael R.; Glassgold, Alfred E.

    1993-01-01

    We have detected forbidden O I 63 micron and forbidden Si II 35 micron emission from the oxygen-rich, M2 lab supergiant, Alpha Orionis (Betelgeuse). The forbidden O I line flux is 2.4 +/- 0.2 x 10 exp -18 W/sq cm, and the forbidden Si II line flux is 0.9 +/- 0.4 x 10 exp -18 W/sq cm. These fluxes are consistent with the thermal model of Rodgers and Glassgold (1991), which indicates that the emission arises in dense, warm gas in Alpha Ori's inner envelope and implies that nearly all of the available O and Si is in atomic form. This is the first reported detection of FIR, fine-structure emission from the inner or transition region of a circumstellar envelope, where molecules and dust are expected to form.

  2. PU.1 is a component of a multiprotein complex which binds an essential site in the murine immunoglobulin lambda 2-4 enhancer.

    PubMed

    Eisenbeis, C F; Singh, H; Storb, U

    1993-10-01

    B-cell-specific enhancers have been identified in the immunoglobulin lambda locus 3' of each constant-region cluster. These enhancers contain two distinct domains, lambda A and lambda B, which are essential for enhancer function. lambda B contains a near-consensus binding site for the Ets family of transcription factors. In this study, we have identified a B-cell-specific protein complex which binds the lambda B motif of the lambda 2-4 enhancer in vitro and appears necessary for the activity of the enhancer in vivo, since mutations in lambda B which prevent this interaction also eliminate enhancer function. This complex contains PU.1, a member of the Ets family, and a transcriptional activator whose expression is restricted to cells of the hematopoietic system with the exception of T lymphocytes. In addition, it contains a factor which binds specifically to a region adjacent to the PU.1 binding site. This factor cannot bind lambda B autonomously but appears to require interaction with the PU.1 protein to stabilize its association with the DNA. This complex may be identical or related to the PU.1/NF-EM5 complex which interacts with a homologous DNA element in the immunoglobulin kappa 3' enhancer. PMID:8413244

  3. Reevaluation of the reported observation of the {sub {lambda}}{sub {lambda}}{sup 4}H hypernucleus

    SciTech Connect

    Randeniya, S. D.; Hungerford, E. V.

    2007-12-15

    The results of experiment E906, undertaken at the Alternating Gradient Synchrotron of the Brookhaven National Laboratory (BNL-AGS), were reanalyzed to clarify the signature of the decays of the double- and single-{lambda} hypernuclei that could have been produced in this experiment. This reanalysis indicates that instead of the reported decay of {sub {lambda}}{sub {lambda}}{sup 4}H through a proposed resonance in {sub {lambda}}{sup 4}He, it is more probable that the decay of the {sub {lambda}}{sub {lambda}}{sup 7}He hypernucleus was observed. This decay was accompanied by a background of coincident decays of pairs of the single hypernuclear fragments {sub {lambda}}{sup 3}H with {sub {lambda}}{sup 4}H, {sub {lambda}}{sup 3}H with {sub {lambda}}{sup 3}H, and {sub {lambda}}{sup 4}H with {sub {lambda}}{sup 4}H. An attempt was also made to determine if any other double or coincident single hypernuclear species could be observed in the data.

  4. {lambda}-{sigma} coupling effect in the neutron-rich {lambda} hypernucleus {sub {lambda}}{sup 10}Li in a microscopic shell-model calculation

    SciTech Connect

    Umeya, A.; Harada, T.

    2009-02-15

    We investigate the structure of the neutron-rich {lambda}-hypernucleus {sub {lambda}}{sup 10}Li by using microscopic shell-model calculations considering a {lambda}-{sigma} coupling effect. The calculated {sigma}-mixing probability in the {sub {lambda}}{sup 10}Li ground state is found to be about 0.34% that is coherently enhanced by the {lambda}-{sigma} coupling configurations, leading to the energy shift 0.28 MeV that is about 3 times larger than that in {sub {lambda}}{sup 7}Li. The importance of the {sigma} configuration obtained by the {sigma}N interaction and the potentiality of the neutron-rich environment are discussed.

  5. The lambda point experiment in microgravity

    NASA Technical Reports Server (NTRS)

    Lipa, J. A.

    1988-01-01

    The motivation and potential for performing very high resolution measurements of the heat capacity singularity at the lambda point of helium in microgravity conditions was briefly discussed. It is clear that tests extending deep into the asymptotic region can be performed, where the theoretical predictions take on their simplest form. This advantageous situation should lead to a major improvement in the understanding of the range of applicability of current theoretical ideas in this field. The lambda transition holds out the prospect of giving the maximum advance of any system, and with the application of cryogenic techniques, the potential of this system can be realized. The technology for the initial experiments is already developed, and results could be obtained in 1990.

  6. The {Lambda}(1405) in Full QCD

    SciTech Connect

    Menadue, Benjamin J.; Kamleh, Waseem; Leinweber, Derek B.; Mahbub, M. Selim

    2011-12-14

    At 1405.1 MeV, the lowest-lying negative-parity state of the {Lambda} baryon lies surprising low. Indeed, this is lower than the lowest negative-parity state of the nucleon, even though the {Lambda}(1405) possesses a valence strange quark. However, previous Lattice QCD studies have been unable to identify such a low-lying state. Using the PACS-CS (2+1)-flavour full-QCD ensembles, available through the ILDG, we utilise a variational analysis with source and sink smearing to isolate this elusive state. We find three low-lying odd-parity states, and for the first time reproduce the correct level ordering with respect to the nearby scattering thresholds.

  7. Análisis y determinación de parámetros físicos de estrellas de tipo FU Orionis

    NASA Astrophysics Data System (ADS)

    Gramajo, L.; Gómez, M.; Whitney, B.

    FU Orionis stars (FUORs) are pre-main sequence objects that periodically incur in a steeply increase of brightness (outburst) of DeltaV~ 6 mag in a period of ~ 10 yr, followed by a gradual descent to the original magnitude in an interval of time of ~100 yr. In this contribution we present initial results on the modeling of the spectral energy distributions (SEDs) of a group of 7 FU Orionis stars: FU Ori, V1515 Cyg, V1057 Cyg, Z CMa, BBW 76, V1735 Cyg, and V883 Ori. We initially used the grid of SEDs calculated by Robitaille et al. (2006). This solution was refined applying the code developed by Whitney et al. (2003). We derived physical and geometrical parameters for the disks of these FUORs. We compared these properties with those of ''canonical'' T Tauri disks. FULL TEXT IN SPANISH

  8. Fully correlated study of {sub {lambda}}{sub {lambda}}{sup 6}He hypernucleus including {lambda}N space-exchange correlations

    SciTech Connect

    Usmani, A. A.; Hasan, Z.

    2006-09-15

    We present a fully correlated study of the six-body {sub {lambda}}{sub {lambda}}{sup 6}He hypernucleus. The wave function involves all relevant dynamic correlations as well as the space-exchange correlation (SEC). Calculations for energy breakdown, {lambda}{lambda}-separation energy, nuclear core polarization, and point proton radius have been performed. The baryon density profiles have also been calculated. Effect of SEC on all these physical observables is found to be significant. The findings suggest that a study ignoring SEC would be deficient.

  9. Trivalent iron induced gelation in lambda-carrageenan

    SciTech Connect

    Running, Cordelia A.; Falshaw, Ruth; Janaswamy, Srinivas

    2012-05-24

    This communication reports gelation of lambda-carrageenan, for the first time, in the presence of trivalent iron ions. Kappa-, iota- and lambda-carrageenans are sulfated polysaccharides used extensively in food, pharmaceutical and medical applications. Kappa- and iota-carrageenans show gelation in the presence of mono- and di-valent ions, but lambda-carrageenan yields only viscous solutions. Our results show that gelation in lambda-carrageenan indeed is possible, but with trivalent ions. X-ray fiber diffraction patterns of iron (III)-lambda-carrageenan are characteristic of highly oriented and polycrystalline fibers containing well resolved Bragg reflections. The elastic modulus (G*) of the product is far greater than the loss modulus (G*) indicating the thermal stability of lambda-carrageenan in the presence of iron (III) ions. This novel finding has potential to expand lambda-carrageenan's current utility beyond a viscosifying agent.

  10. A white dwarf companion to the main-sequence star 4 Omicron(1) Orionis and the binary hypothesis for the origin of peculiar red giants

    NASA Technical Reports Server (NTRS)

    Ake, Thomas B.; Johnson, Hollis R.

    1988-01-01

    Ultraviolet spectra of the peculiar red giants (PRGs) called MS stars are investigated, and the discovery of a white dwarf (WD) companion to the MS star 4 Omicron(1) Orionis is reported. The observations and data analysis are discussed and compared with those for field WDs in order to derive parameters for the WD and the luminosity of the primary. Detection limits for the other MS stars investigated are derived, and the binary hypothesis for PRGs is reviewed.

  11. MASS FUNCTION PREDICTIONS BEYOND {Lambda}CDM

    SciTech Connect

    Bhattacharya, Suman; Lukic, Zarija; Habib, Salman; Heitmann, Katrin; White, Martin; Wagner, Christian

    2011-05-10

    The statistics of dark matter halos is an essential component of precision cosmology. The mass distribution of halos, as specified by the halo mass function, is a key input for several cosmological probes. The sizes of N-body simulations are now such that, for the most part, results need no longer be statistics-limited, but are still subject to various systematic uncertainties. Discrepancies in the results of simulation campaigns for the halo mass function remain in excess of statistical uncertainties and of roughly the same size as the error limits set by near-future observations; we investigate and discuss some of the reasons for these differences. Quantifying error sources and compensating for them as appropriate, we carry out a high-statistics study of dark matter halos from 67 N-body simulations to investigate the mass function and its evolution for a reference {Lambda}CDM cosmology and for a set of wCDM cosmologies. For the reference {Lambda}CDM cosmology (close to WMAP5), we quantify the breaking of universality in the form of the mass function as a function of redshift, finding an evolution of as much as 10% away from the universal form between redshifts z = 0 and z = 2. For cosmologies very close to this reference we provide a fitting formula to our results for the (evolving) {Lambda}CDM mass function over a mass range of 6 x 10{sup 11}-3 x 10{sup 15} M{sub sun} to an estimated accuracy of about 2%. The set of wCDM cosmologies is taken from the Coyote Universe simulation suite. The mass functions from this suite (which includes a {Lambda}CDM cosmology and others with w {approx_equal} -1) are described by the fitting formula for the reference {Lambda}CDM case at an accuracy level of 10%, but with clear systematic deviations. We argue that, as a consequence, fitting formulae based on a universal form for the mass function may have limited utility in high-precision cosmological applications.

  12. Differential Photoproduction Cross Sections of the Sigma0(1385), Lambda(1405), and Lambda(1520)

    SciTech Connect

    Moriya, Kei; Schumacher, Reinhard A.

    2013-10-01

    We report the exclusive photoproduction cross sections for the Sigma(1385), Lambda(1405), and Lambda(1520) in the reactions gamma + p -> K+ + Y* using the CLAS detector for energies from near the respective production thresholds up to a center-of-mass energy W of 2.85 GeV. The differential cross sections are integrated to give the total exclusive cross sections for each hyperon. Comparisons are made to current theoretical models based on the effective Lagrangian approach and fitted to previous data. The accuracy of these models is seen to vary widely. The cross sections for the Lambda(1405) region are strikingly different for the Sigma+pi-, Sigma0 pi0, and Sigma- pi+ decay channels, indicating the effect of isospin interference, especially at W values close to the threshold.

  13. Infrared imaging and millimetre continuum mapping of Herbig Ae/Be and FU Orionis stars

    NASA Astrophysics Data System (ADS)

    Henning, Th.; Burkert, A.; Launhardt, R.; Leinert, Ch.; Stecklum, B.

    1998-08-01

    The goal of this paper is a detailed analysis of the dusty environment of Herbig Ae/Be stars and FU Orionis objects. For this purpose we mapped 22 regions at 1.3 mm wavelength containing 25 target objects. We found that it is indispensable to perform mapping in contrast to pointed On-On measurements in order to obtain the correct distribution of cold material around young stellar objects and to relate 1.3 mm flux densities to individual sources. To get reliable information about the structure and shape of the dust configurations and their relation to the stellar sources, we superimposed the millimetre maps on near-infrared images. The comparison of the data demonstrated that some of the Herbig Ae/Be stars are not associated with the peak of the millimetre emission. This is obviously the case for V 376 Cas/LkHα 198, MWC 137, CoD-42(deg) 11721, and V 1685 Cyg/V 1686 Cyg. We found two different morphologies of the dust envelopes: 6 regions show a compact structure, whereas 12 regions are characterized by a core/envelope structure. The ``disk'' objects AB Aur and HD 163296 show only a compact core and are not surrounded by an extended envelope. We did not detect HK Ori, HD 250550, LkHα 25, and V 1515 Cyg which all have low IRAS luminosities. Based on the flux densities derived from the millimetre maps, we estimated characteristic physical parameters like density and mass assuming optically thin emission. The total masses of the circumstellar regions around the Herbig Ae/Be stars with core/envelope structure and with ``genuine" point-like millimetre sources are 80+/-60 Msun\\ and 0.15+/-0.15 Msun, respectively. The lowest and highest masses of the circumstellar material were found around AB Aur (0.03 Msun) and CoD-42(deg) 11721 (1100 Msun), respectively. The average densities in the cores range from 10(5) to 10(8) cm(-3) . The densities of the extended envelopes are of the order of 10(4) to 10(5) cm(-3) . In addition, we combined the measured millimetre flux densities

  14. Measurement of transverse {lambda} and {lambda}-bar polarization at COMPASS

    SciTech Connect

    Ferrero, A.

    2007-06-13

    New data on hyperon polarization in semi-inclusive deep inelastic scattering have been collected by the COMPASS collaboration at CERN during the years 2002-2004, using a beam of longitudinally polarized muons of 160 GeV/c and a 6LiD target that can be polarized both longitudinally and transversely. The various combinations of beam and target polarizations allow for the study of a wide variety of hyperon polarization effects. Here we present preliminary results on the transverse polarization of {lambda} and {lambda}-bar produced both with unpolarized and transversely polarized deuteron targets.

  15. T(sub lambda) Depression by a Heat Current Along the lambda-Line

    NASA Technical Reports Server (NTRS)

    Liu, Yuanming; Larson, Melora; Iraelsson, Ulf E.

    1999-01-01

    We report measurements of the depression of the superfluid transition temperature by a heat current (1 less than or = Q less than or = 100 microW/sq cm) along the lambda-line (SVP less than or = P less than or = 21.6 bar). At P = 21.6 bar, measurements were also performed in a reduced gravity (0.2g). Experimental results show that the pressure dependence of the depression and the gravity effect on the measurements are small, in qualitative agreement with theoretical predictions. Keywords: superfluid helium; Lambda transition; heat current

  16. Lambda Baryon a Production in 91 GEV Positron - Collisions

    NASA Astrophysics Data System (ADS)

    Routenburg, Paul

    1992-01-01

    An analysis of Lambda + | Lambda production in the data collected with the OPAL detector during 1990 is presented. A total inclusive rate is determined and checked through detailed systematic studies. This rate is found to be 0.356 +/- 0.011 (stat.) +/- 0.028 (syst.) per multihadron event. The inclusive cross sections as a function of the fractional Lambda energy (x _{E}) and xi (xi = ln(1/x_{p }), where x_{p} is the fractional Lambda momentum) are determined and compared to the predictions of the HERWIG 5.0 and JETSET 7.2 Monte Carlos as tuned to agree with global event shapes at an average centre-of-mass energy of 91 GeV. The overall Lambda rate is in agreement with the JETSET prediction but less than that predicted by HERWIG. The fragmentation function observed is softer than predicted by either Monte Carlo. Scaling violations are observed in the x_{E } distribution compared to the observations between 29 and 35 GeV. This is attributed to increased gluon radiation. A study is then made of the Lambda decay length distribution, and of the production and decay angles. Reasonable agreement is found between the data and the expectations. There is some indication that the Lambda rate increases faster with event sphericity than does the charged multiplicity. This effect is thought to be due to increased baryon production in gluon fragmentation. Finally, an investigation into Lambda - | Lambda, Lambda - Lambda and | Lambda - | Lambda production in the same event is presented. The results support local baryon number conservation and agree with the JETSET prediction. It is also shown that an additional meson is produced between the baryon and the antibaryon a significant fraction of the time.

  17. Measurement of the Lambda0b lifetime in the decay lambda0b--> J/psiLambda0 with the D0 detector.

    PubMed

    Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Agelou, M; Agram, J-L; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Anderson, S; Andrieu, B; Arnoud, Y; Askew, A; Asman, B; Atramentov, O; Autermann, C; Avila, C; Badaud, F; Baden, A; Baldin, B; Balm, P W; Banerjee, S; Barberis, E; Bargassa, P; Baringer, P; Barnes, C; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Bean, A; Beauceron, S; Begel, M; Bellavance, A; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Binder, M; Black, K M; Blackler, I; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Blumenschein, U; Boehnlein, A; Boeriu, O; Bolton, T A; Borcherding, F; Borissov, G; Bos, K; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Buchanan, N J; Buchholz, D; Buehler, M; Buescher, V; Burdin, S; Burnett, T H; Busato, E; Butler, J M; Bystricky, J; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Chapin, D; Charles, F; Cheu, E; Chevalier, L; Cho, D K; Choi, S; Christiansen, T; Christofek, L; Claes, D; Clément, B; Clément, C; Coadou, Y; Cooke, M; Cooper, W E; Coppage, D; Corcoran, M; Coss, J; Cothenet, A; Cousinou, M-C; Crépé-Renaudin, S; Cristetiu, M; Cummings, M A C; Cutts, D; da Motta, H; Davies, B; Davies, G; Davis, G A; De, K; de Jong, P; de Jong, S J; De La Cruz-Burelo, E; De Oliveira Martins, C; Dean, S; Déliot, F; Delsart, P A; Demarteau, M; Demina, R; Demine, P; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Doidge, M; Dong, H; Doulas, S; Duflot, L; Dugad, S R; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Edwards, T; Ellison, J; Elmsheuser, J; Eltzroth, J T; Elvira, V D; Eno, S; Ermolov, P; Eroshin, O V; Estrada, J; Evans, D; Evans, H; Evdokimov, A; Evdokimov, V N; Fast, J; Fatakia, S N; Feligioni, L; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fortner, M; Fox, H; Freeman, W; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; Garcia, C; Garcia-Bellido, A; Gardner, J; Gavrilov, V; Gay, P; Gelé, D; Gelhaus, R; Genser, K; Gerber, C E; Gershtein, Y; Ginther, G; Golling, T; Gómez, B; Gounder, K; Goussiou, A; Grannis, P D; Greder, S; Greenlee, H; Greenwood, Z D; Gregores, E M; Gris, Ph; Grivaz, J-F; Groer, L; Grünendahl, S; Grünewald, M W; Gurzhiev, S N; Gutierrez, G; Gutierrez, P; Haas, A; Hadley, N J; Hagopian, S; Hall, I; Hall, R E; Han, C; Han, L; Hanagaki, K; Harder, K; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hohlfeld, M; Hong, S J; Hooper, R; Houben, P; Hu, Y; Huang, J; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jain, V; Jakobs, K; Jenkins, A; Jesik, R; Johns, K; Johnson, M; Jonckheere, A; Jonsson, P; Jöstlein, H; Juste, A; Kado, M M; Käfer, D; Kahl, W; Kahn, S; Kajfasz, E; Kalinin, A M; Kalk, J; Karmanov, D; Kasper, J; Kau, D; Kehoe, R; Kermiche, S; Kesisoglou, S; Khanov, A; Kharchilava, A; Kharzheev, Y M; Kim, K H; Klima, B; Klute, M; Kohli, J M; Kopal, M; Korablev, V M; Kotcher, J; Kothari, B; Koubarovsky, A; Kozelov, A V; Kozminski, J; Krzywdzinski, S; Kuleshov, S; Kulik, Y; Kunori, S; Kupco, A; Kurca, T; Lager, S; Lahrichi, N; Landsberg, G; Lazoflores, J; Le Bihan, A-C; Lebrun, P; Lee, S W; Lee, W M; Leflat, A; Lehner, F; Leonidopoulos, C; Lewis, P; Li, J; Li, Q Z; Lima, J G R; Lincoln, D; Linn, S L; Linnemann, J; Lipaev, V V; Lipton, R; Lobo, L; Lobodenko, A; Lokajicek, M; Lounis, A; Lubatti, H J; Lueking, L; Lynker, M; Lyon, A L; Maciel, A K A; Madaras, R J; Mättig, P; Magerkurth, A; Magnan, A-M; Makovec, N; Mal, P K; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; Martens, M; Mattingly, S E K; Mayorov, A A; McCarthy, R; McCroskey, R; Meder, D; Melanson, H L; Melnitchouk, A; Merkin, M; Merritt, K W; Meyer, A; Miettinen, H; Mihalcea, D; Mitrevski, J; Mokhov, N; Molina, J; Mondal, N K; Montgomery, H E; Moore, R W; Muanza, G S; Mulders, M; Mutaf, Y D; Nagy, E; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Nelson, S; Neustroev, P; Noeding, C; Nomerotski, A; Novaes, S F; Nunnemann, T; Nurse, E; O'dell, V; O'Neil, D C; Oguri, V; Oliveira, N; Oshima, N; Otero Y Garzón, G J; Padley, P; Parashar, N; Park, J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Perea, P M; Perez, E; Peters, O; Pétroff, P; Petteni, M; Phaf, L; Piegaia, R; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pope, B G; da Silva, W L Prado; Prosper, H B; Protopopescu, S; Przybycien, M B; Qian, J; Quadt, A; Quinn, B; Rani, K J; Rapidis, P A; Ratoff, P N; Reay, N W; Reucroft, S; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Royon, C; Rubinov, P; Ruchti, R; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A; Savage, G; Sawyer, L; Scanlon, T; Schamberger, R D; Schellman, H; Schieferdecker, P; Schmitt, C; Schukin, A A; Schwartzman, A; Schwienhorst, R; Sengupta, S; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shephard, W D; Shpakov, D; Sidwell, R A; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smith, R P; Smolek, K; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Song, X; Song, Y; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Souza, M; Spurlock, B; Stanton, N R; Stark, J; Steele, J; Steinbrück, G; Stevenson, K; Stolin, V; Stone, A; Stoyanova, D A; Strandberg, J; Strang, M A; Strauss, M; Ströhmer, R; Strovink, M; Stutte, L; Sumowidagdo, S; Sznajder, A; Talby, M; Tamburello, P; Taylor, W; Telford, P; Temple, J; Tentindo-Repond, S; Thomas, E; Thooris, B; Tomoto, M; Toole, T; Torborg, J; Towers, S; Trefzger, T; Trincaz-Duvoid, S; Tuchming, B; Tully, C; Turcot, A S; Tuts, P M; Uvarov, L; Uvarov, S; Uzunyan, S; Vachon, B; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Verzocchi, M; Villeneuve-Seguier, F; Vlimant, J-R; Von Toerne, E; Vreeswijk, M; Vu Anh, T; Wahl, H D; Walker, R; Wang, L; Wang, Z-M; Warchol, J; Warsinsky, M; Watts, G; Wayne, M; Weber, M; Weerts, H; Wegner, M; Wermes, N; White, A; White, V; Whiteson, D; Wicke, D; Wijngaarden, D A; Wilson, G W; Wimpenny, S J; Wittlin, J; Wobisch, M; Womersley, J; Wood, D R; Wyatt, T R; Xu, Q; Xuan, N; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yen, Y; Yip, K; Youn, S W; Yu, J; Yurkewicz, A; Zabi, A; Zatserklyaniy, A; Zdrazil, M; Zeitnitz, C; Zhang, D; Zhang, X; Zhao, T; Zhao, Z; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zitoun, R; Zutshi, V; Zverev, E G; Zylberstejn, A

    2005-03-18

    We present measurements of the Lambda(0)(b) lifetime in the exclusive decay channel Lambda(0)(b)--> J/psiLambda(0), with J/psi--> mu(+)mu(-) and Lambda(0)--> ppi(-), the B0 lifetime in the decay B0-->J/psiK(0)(S) with J/psi--> mu(+)mu(-) and K(0)(S)-->pi(+)pi(-), and the ratio of these lifetimes. The analysis is based on approximately 250 pb(-1) of data recorded with the D0 detector in pp collisions at sqrt[s] = 1.96 TeV. The Lambda(0)(b) lifetime is determined to be tau(Lambda(0)(b)) = 1.22(+0.22)(-0.18)(stat) +/- 0.04(syst) ps, the B0 lifetime tau(B0) = 1.40(+0.11)(-0.10)(stat) +/- 0.03(syst) ps, and the ratio tau(Lambda(0)(b))/tau(B0) = 0.87(+0.17)(-0.14)(stat) +/- 0.03(syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Lambda(0)(b) lifetime based on a fully reconstructed decay channel. PMID:15783476

  18. Rabi resonances in the {lambda} excitation scheme

    SciTech Connect

    Godone, Aldo; Micalizio, Salvatore; Levi, Filippo

    2002-12-01

    We consider the interaction of a three-level system with phase-modulated resonant fields in the {lambda} excitation scheme. We treat theoretically the case of a sinusoidal phase modulation, a phase step perturbation, and a stochastic phase modulation. The appearance of a Rabi resonance both in the spectrum of the optical transmitted signal (electromagnetically induced transparency) and in the spectrum of the microwave emission (coherent population trapping maser) is considered in detail. All the theoretical results are compared with the analogous ones reported for the two-level system and with our experimental observations obtained for the case of rubidium in a buffer gas.

  19. {Lambda}(1520) photoproduction with Regge contribution

    SciTech Connect

    Nam, Seung-il; Yu, Byung-Geel; Kao, Chung-Wen

    2011-10-21

    In this talk, we report our recent progresses on the {Lambda}(1520) photoproduction using the effective Lagrangian approach. In addition to the tree-level Born diagrams, we take into account the Regge-trajectories for the possible strange-meson exchanges in the t channel. We compute the angular and energy dependences of the production process, including polarization observables, such as the photon-beam asymmetry and the polarization-transfer coefficients, resulting in good qualitative agreement with current experimental data. We also compute the K{sup -} angle distribution function in the Gottfried-Jackson frame, using the polarization-transfer coefficients in the z direction.

  20. Aetherizing Lambda: Barotropic fluids as dark energy

    SciTech Connect

    Linder, Eric V.; Scherrer, Robert J.

    2009-07-15

    We examine the class of barotropic fluid models of dark energy, in which the pressure is an explicit function of the density, p=f({rho}). Through general physical considerations we constrain the asymptotic past and future behaviors and show that this class is equivalent to the sum of a cosmological constant and a decelerating perfect fluid, or 'aether', with w{sub AE}{>=}0. Barotropic models give substantially disjoint predictions from quintessence, except in the limit of {lambda}CDM. They are also interesting in that they simultaneously can ameliorate the coincidence problem and yet 'predict' a value of w{approx_equal}-1.

  1. Measurement of the Lambda/b lifetime in Lambda/b to Lambda/c pi decays at the Collider Detector at Fermilab

    SciTech Connect

    Mumford, Jonathan Reid; /Johns Hopkins U.

    2008-10-01

    The lifetime of the {Lambda}{sub b}{sup 0} baryon (consisting of u, d and b quarks) is the theoretically most interesting of all b-hadron lifetimes. The lifetime of {Lambda}{sub b}{sup 0} probes our understanding of how baryons with one heavy quark are put together and how they decay. Experimentally however, measurements of the {Lambda}{sub b}{sup 0} lifetime have either lacked precision or have been inconsistent with one another. This thesis describes the measurement of {Lambda}{sub b}{sup 0} lifetime in proton-antiproton collisions with center of mass energy of 1.96 TeV at Fermilab's Tevatron collider. Using 1070 {+-} 60pb{sup -1} of data collected by the Collider Detector at Fermilab (CDF), a clean sample of about 3,000 fully-reconstructed {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -} decays (with {Lambda}{sub c}{sup +} subsequently decaying via {Lambda}{sub c}{sup +} {yields} p{sup +} K{sup -} {pi}{sup +}) is used to extract the lifetime of the {Lambda}{sub b}{sup 0} baryon, which is found to be c{tau}({Lambda}{sub b}{sup 0}) = 422.8 {+-} 13.8(stat) {+-} 8.8(syst){micro}m. This is the most precise measurement of its kind, and is even better than the current world average. It also settles the recent controversy regarding the apparent inconsistency between CDF's other measurement and the rest of the world.

  2. A Study of Bbar to Xi_c Lambda_c^- and Bbar to Lambda_c^+ Lambda_c^- Kbar Decays at \\babar

    SciTech Connect

    Aubert, B.

    2007-11-07

    We report measurements of B-meson decays into two- and three-body final states containing two charmed baryons using a sample of 230 million {Upsilon}(4S) {yields} B{bar B} decays. We find significant signals in two modes, measuring branching fractions {beta}(B{sup -} {yields} {Lambda}{sub c}{sup +}{Lambda}{sub c}{sup -}K{sup -}) = (1.14 {+-} 0.15 {+-} 0.17 {+-} 0.60) x 10{sup -3} and {beta}(B{sup -}{yields} {Xi}{sup 0}{sub c}{bar {Lambda}}{sub c}{sup -}) x {beta}({Xi}{sup 0}{sub c} {yields} {Xi}{sup -}{pi}{sup +}) = (2.08 {+-} 0.65 {+-} 0.29 {+-} 0.54) x 10{sup -5}, where the uncertainties are statistical, systematic, and from the branching fraction {beta}({Lambda}{sup +}{sub c} {yields} pK{sup -}{pi}{sup +}), respectively. We also set upper limits at the 90% confidence level on two other modes: {beta}({bar {beta}}{sup 0} {yields} {Xi}{sup +}{sub c}{bar {Lambda}}{sup -}{sub c}) x {beta}({Xi}{sup +}{sub c} {yields} {Xi}{sup -}{pi}{sup +}{pi}{sup +}) < 5.6 x 10{sup -5} and {beta}({bar B}{sup 0} {yields} {Lambda}{sup +}{sub c}{bar {Lambda}}{sup -}{sub c}{bar K}{sup 0}) < 1.5 x 10{sup -3}. We observe structure centered at an invariant mass of 2.93 GeV/c{sup 2} in the {Lambda}{sup +}{sub c}K{sup -} mass distribution of the decay B{sup -} {yields} {Lambda}{sup +}{sub c}{bar {Lambda}}{sup -}{sub c}K{sup -}.

  3. On the local behaviour of the multidimensional {Lambda}-variation

    SciTech Connect

    Bakhvalov, Alexandr N

    2011-01-14

    Let two classes ({Lambda}{sup 1},...,{Lambda}{sup m})BV and (M{sup 1},...,M{sup m})BV on an interval {Delta} be given. In the paper, we find necessary and sufficient conditions for the {Lambda}-variation of any function in the M-class, over a neighbourhood of every regular point, to tend to zero as the neighbourhood decreases. Bibliography: 10 titles.

  4. First measurement of the ratio of branching fractions BR(Lambda(b) to Lambda(c) mu nu)/BR(Lambda(b) to Lambda(c) pi) at CDF II

    SciTech Connect

    Yu, Shin-shan

    2005-01-01

    In this dissertation, we measure the properties of the lowest-mass beauty baryon, {Lambda}{sub b}. Baryons are the bound states of three quarks. Protons and neutrons, constituents of atomic nuclei, are the most common baryons. Other types of baryons can be produced and studied in the high-energy collider environment. Three-body dynamics makes baryons composed of low mass quarks difficult to study. On the other hand, baryons with one heavy quark simplify the theoretical treatment of baryon structure, since the heavy quark can be treated the same way as the nucleus in the atom. The {Lambda}{sub b} is composed of u, d, and b quarks, where the b quark is much heavier than the other two. Although, it is accessible, little is known about {Lambda}{sub b}. In 1991, UA1 [1] reconstructed 9 {+-} 1 {Lambda}{sub b} {yields} J/{Psi}{Lambda} candidates. In 1996, ALEPH and DELPHI reconstructed the decay {Lambda}{sub b} {yields} {Lambda}{sub c}{sup +}{pi}{sup -} and found only 3-4 candidates [2, 3]. ALEPH measured a {Lambda}{sub b} mass of 5614 {+-} 21 MeV/c{sup 2}, while DELPHI measured 5668 {+-} 18 MeV/c{sup 2}, about 2 {sigma} higher. Subsequently, CDF-I observed 20 {Lambda}{sub b} {yields} J/{Psi}{Lambda} events [4], confirmed the existence of {Lambda}{sub b} unambiguously and made a more precise measurement of {Lambda}{sub b} mass, 5621 {+-} 5 MeV/c{sup 2}. A recent CDF-II measurement by Korn [5] yields 5619.7 {+-} 1.7 MeV/c{sup 2}, which will significantly improve the current world average, 5624 {+-} 9 MeV/c{sup 2}, and resolve the discrepancy of ALEPH and DELPHI.

  5. The fluxonium as a lambda system

    NASA Astrophysics Data System (ADS)

    Vool, U.; Kou, A.; Smith, W. C.; Serniak, K.; Shankar, S.; Girvin, S. M.; Devoret, M. H.

    A lambda system is a 3-level system in which two low-energy states can transition to a third higher-energy state by a coherent drive but not to each other. Lambda systems are commonly implemented in systems relying on atomic transitions. In the field of superconducting quantum circuits, the fluxonium qubit, an artificial atom consisting of a Josephson junction shunted by a super-inductance, is a unique artificial atom with highly non-linear energy levels. At half-flux quantum it has two low-energy states with a long energy lifetime, but it is difficult to perform fast quantum gates in this manifold. Employing the higher 2nd excited state as an intermediate level would be much more efficient. However, selection rules in the fluxonium qubit prohibit transitions between low-energy states and higher-energy states of the same parity. In this talk, we will introduce a way to create formerly forbidden transitions between levels of the fluxonium qubit - thus creating a more interesting artificial atom and a useful tool for future superconducting quantum circuits. Work supported by ARO, ONR, AFOSR and YINQE.

  6. The LAMBDA photon-counting pixel detector

    NASA Astrophysics Data System (ADS)

    Pennicard, D.; Lange, S.; Smoljanin, S.; Hirsemann, H.; Graafsma, H.; Epple, M.; Zuvic, M.; Lampert, M.-O.; Fritzsch, T.; Rothermund, M.

    2013-03-01

    The Medipix3 photon-counting detector chip has a number of novel features that are attractive for synchrotron experiments, such as a high frame rate with zero dead time and high spatial resolution. DESY are developing a large-area Medipix3-based detector array (LAMBDA). A single LAMBDA module consists of 2 by 6 Medipix3 chips on a ceramic carrier board, bonded to either a single large silicon sensor or two smaller high-Z sensors. The readout system fits behind the carrier board to allow module tiling, and uses a large on-board RAM and multiple 10 Gigabit Ethernet links to permit high-speed readout. Currently, the first large silicon modules have been constructed and read out at low speed, and the firmware for highspeed readout is being developed. In addition to these silicon sensors, we are developing a germanium hybrid pixel detector in collaboration with Canberra for higher-energy beamlines. Canberra have produced a set of 256-by-256-pixel planar germanium sensors with 55μm pitch, and these are currently being bonded to Medipix3 readout chips by Fraunhofer IZM (Berlin).

  7. ON THE BINDING ENERGY PARAMETER {lambda} OF COMMON ENVELOPE EVOLUTION

    SciTech Connect

    Xu Xiaojie; Li Xiangdong

    2010-06-10

    The binding energy parameter {lambda} plays an important role in common envelope evolution. Previous works have already pointed out that {lambda} varies throughout the stellar evolution, though it has been adopted as a constant in most of the population synthesis calculations. We have systematically calculated the binding energy parameter {lambda} for both Population I and Population II stars of masses 1-20 M {sub sun}, taking into account the contribution from the internal energy of stellar matter. We present fitting formulae for {lambda} that can be incorporated into future population synthesis investigations. We also briefly discuss the possible applications of the results in binary evolutions.

  8. Rare {Lambda}{sub b} decays in a quark model

    SciTech Connect

    Mott, L.; Roberts, W.

    2010-08-05

    Hadronic form factors for the rare weak transitions {Lambda}{sub b{yields}{Lambda}}{sup (*)} are calculated using a nonrelativistic quark model. The form factors obtained in this way are found to satisfy the relationships expecetd from the heavy quark effective theory. Differential decay rates and branching ratios are calculated for the dileptonic decays {Lambda}{sub b{yields}{Lambda}}{sup (*)}l{sup +}l{sup -}, for both ground state and excited daughter baryons. Inclusion of the long distance contributions from charmonium resonances significantly enhances the decay rates. Future work is outlined.

  9. Charge-symmetry breaking {Lambda}-nucleon interaction

    SciTech Connect

    Bodmer, A.R.; Murali, M.; Usmani, Q.N.

    1995-08-01

    Some time ago we showed that the charge-symmetry-breaking interaction, as obtained from the mass four hypernuclei ({sub {Lambda}}{sup 4}H, {sub {Lambda}}{sup 4}He), was spin-independent; a result which cannot be understood with the conventional meson-exchange models. The calculations of ({sub {Lambda}}{sup 4}H, {sub {Lambda}}{sup 4}He) are currently being extended to include noncentral nuclear and hypernuclear forces which could modify this result. At a more fundamental level we intend to study quark-structure contributions to the charge-symmetry-breaking interaction.

  10. Remarks on the generalized Tukey's lambda family of distributions

    SciTech Connect

    Lam, H.; Bowman, K.O.; Shenton, L.R.

    1980-01-01

    The family of curves generated by the mapping of the uniform density F/sup -1/(lambda) = ..cap alpha.. + ..beta..(lambda/sup ..gamma..delta/ - (1-lambda)/sup ..gamma../)/..gamma.., 0 < lambda < 1, is considered. Primary interest is the application of the above density to approximating theoretical distribution functions of test statistics such as S.D., skewness, and kurtosis under non-normality. Moments are straight forward to evaluate in terms of gamma functions, or polygamma functions in special cases. 1 figure, 8 tables. (RWR)

  11. Analysis of the {Lambda}{sub b{yields}{Lambda}}l{sup +}l{sup -} decay in QCD

    SciTech Connect

    Aliev, T. M.; Savci, M.; Azizi, K.

    2010-03-01

    Taking into account the {Lambda} baryon distribution amplitudes and the most general form of the interpolating current of the {Lambda}{sub b}, the semileptonic {Lambda}{sub b{yields}{Lambda}}l{sup +}l{sup -} transition is investigated in the framework of the light cone QCD sum rules. Sum rules for all 12 form factors responsible for the {Lambda}{sub b{yields}{Lambda}}l{sup +}l{sup -} decay are constructed. The obtained results for the form factors are used to compute the branching fraction. A comparison of the obtained results with the existing predictions of the heavy quark effective theory is presented. The results of the branching ratio shows the detectability of this channel at the Large Hadron Collider beauty in the near future is quite high.

  12. {lambda}N space-exchange correlation effects in the {sub {lambda}}{sup 5}He hypernucleus

    SciTech Connect

    Usmani, A.A.

    2006-01-15

    A complete realistic study of the {sub {lambda}}{sup 5}He hypernucleus is presented using a realistic Hamiltonian and a fully correlated wave function that takes into account all relevant dynamical correlations and {lambda}N space-exchange correlation (SEC). Results are sensitive to SEC, which significantly affects energy breakdown, {lambda}-separation energy, nuclear core polarization, point proton radius, and density profiles.

  13. QCD factorization for {Lambda}{sub b}{sup 0}{yields}{Lambda}{sub c}{sup +}{pi}{sup -}

    SciTech Connect

    Zhang Zhenhua; Guo Xinheng; Lue Gang

    2011-02-01

    We prove that in the limit m{sub b},m{sub c}{yields}{infinity}, with m{sub c}/m{sub b} fixed, factorization holds at order {alpha}{sub s} for the decay {Lambda}{sub b}{sup 0}{yields}{Lambda}{sub c}{sup +}{pi}{sup -}. This proof is done in the infinite-momentum frame in which the momenta of {pi}, {Lambda}{sub c}, and {Lambda}{sub b} go to infinity. Our result is renormalization-scale- and scheme-independent at O({alpha}{sub s}). This is the same as the QCD factorization for B{yields}D{pi}.

  14. Environmental chemistry, ecotoxicity, and fate of lambda-cyhalothrin.

    PubMed

    He, Li-Ming; Troiano, John; Wang, Albert; Goh, Kean

    2008-01-01

    Lambda-cyhalothrin is a pyrethroid insecticide used for controlling pest insects in agriculture, public health, and in construction and households. Lambda-cyhalothrin is characterized by low vapor pressure and a low Henry's law constant but by a high octanol-water partition coefficient (K(ow)) and high water-solid-organic carbon partition coefficient (K(oc)) values. Lambda-cyhalothrin is quite stable in water at pH < 8, whereas it hydrolyzes to form HCN and aldehyde under alkaline conditions. Although lambda-cyhalothrin is relatively photostable under natural irradiation, with a half-life > 3 wk, its photolysis process is fast under UV irradiation, with a half-life < 10 min. The fate of lambda-cyhalothrin in aquatic ecosystems depends on the nature of system components such as suspended solids (mineral and organic particulates) and aquatic organisms (algae, macrophytes, or aquatic animals). Lambda-cyhalothrin residues dissolved in water decrease rapidly if suspended solids and/or aquatic organisms are present because lambda-cyhalothrin molecules are strongly adsorbed by particulates and plants. Adsorbed lambda-cyhalothrin molecules show decreased degradation rates because they are less accessible to breakdown than free molecules in the water column. On the other hand, lambda-cyhalothrin adsorbed to suspended solids or bottom sediments may provide a mechanism to mitigate its acute toxicity to aquatic organisms by reducing their short-term bioavailability in the water column. The widespread use of lambda-cyhalothrin has resulted in residues in sediment, which have been found to be toxic to aquatic organisms including fish and amphipods. Mitigation measures have been used to reduce the adverse impact of lambda-cyhalothrin contributed from agricultural or urban runoff. Mitigation may be achieved by reducing the quantity of runoff and suspended solid content in runoff through wetlands, detention ponds, or vegetated ditches. PMID:18418954

  15. Lambda/2 fringe-spacing interferometer.

    PubMed

    de Chatellus, H Guillet; Pique, J-P

    2009-03-15

    The precision of interferometry is directly linked to the fringe spacing of the recorded interferogram. Whereas all interferometric devices show a fringe spacing equal to a wavelength of the laser light we present a novel scheme of a two-beam interferometer exhibiting a fringe spacing reduced by a factor of 2; the direct detection of the beat signal is replaced with the monitoring of the fluorescence of a twofold degenerate atomic system resonant with the laser. The lambda/2 fringe spacing in the fluorescence signal is demonstrated with a hot sodium vapor excited by a broadband laser tuned to the D1 line. In the saturation regime, the dark fringes are expected to be extremely narrow, leading to the possibility of nanoscale displacement measurements or atom localization. PMID:19282922

  16. ATMOSPHERIC PHASE CORRECTION USING CARMA-PACS: HIGH ANGULAR RESOLUTION OBSERVATIONS OF THE FU ORIONIS STAR PP 13S*

    SciTech Connect

    Perez, Laura M.; Carpenter, John M.; Isella, Andrea; Lamb, James W.; Woody, David P.; Leitch, Erik M.; Muchovej, Stephen J.; Scott, Stephen L.; Zauderer, B. Ashley; Bolatto, Alberto D.; Teuben, Peter J.; Bock, Douglas C.; Carlstrom, John; Culverhouse, Thomas L.; Marrone, Daniel P.; Joy, Marshall; Kwon, Woojin; Plambeck, Richard L.; Wright, Melvyn C. H.

    2010-11-20

    We present 0.''15 resolution observations of the 227 GHz continuum emission from the circumstellar disk around the FU Orionis star PP 13S*. The data were obtained with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) Paired Antenna Calibration System (C-PACS), which measures and corrects the atmospheric delay fluctuations on the longest baselines of the array in order to improve the sensitivity and angular resolution of the observations. A description of the C-PACS technique and the data reduction procedures are presented. C-PACS was applied to CARMA observations of PP 13S*, which led to a factor of 1.6 increase in the observed peak flux of the source, a 36% reduction in the noise of the image, and a 52% decrease in the measured size of the source major axis. The calibrated complex visibilities were fitted with a theoretical disk model to constrain the disk surface density. The total disk mass from the best-fit model corresponds to 0.06 M{sub sun}, which is larger than the median mass of a disk around a classical T Tauri star. The disk is optically thick at a wavelength of 1.3 mm for orbital radii less than 48 AU. At larger radii, the inferred surface density of the PP 13S* disk is an order of magnitude lower than that needed to develop a gravitational instability.

  17. A Simple Calculation in Service of Constraining the Rate of FU Orionis Outburst Events from Photometric Monitoring Surveys

    NASA Astrophysics Data System (ADS)

    Hillenbrand, Lynne A.; Findeisen, Krzysztof P.

    2015-07-01

    The FU Orionis class of young stellar objects is enigmatic and rare. The members are interpreted to be “outbursting,” that is, they are currently in a state of enhanced accretion by several orders of magnitude relative to the more modest disk-to-star accretion rates measured in typical T Tauri stars. They are key to our understanding of the history of stellar mass assembly and pre-main-sequence evolution, and are also critical when considering the chemical and physical evolution of the circumstellar environment—where planets form. A common supposition is that all T Tauri stars repeatedly undergo such outbursts, more frequently in their earlier evolutionary stages when the disks are more massive, so as to build up the requisite amount of stellar mass on the required timescale. However, the actual data supporting this traditional picture of episodically enhanced disk accretion are limited, and the observational properties of the known sample of FU Ori objects are quite diverse. To improve our understanding of these rare objects, we outline the logic used to meaningfully constrain the rate of FU Ori outbursts and present numbers to guide parameter choices in the analysis of time domain surveys.

  18. Properties of the Lambda(1405) Measured at CLAS

    SciTech Connect

    Kei Moriya, Reinhard Schumacher

    2012-04-01

    The nature of the {Lambda}(1405), and its place in the baryon spectrum has remained uncertain for decades. Theoretical studies have shown that it may possess strong dynamical components which are not seen in other well-known baryons. Using the CLAS detector system in Hall B at Jefferson Lab, we have measured the photoproduction reaction {gamma} + p {yields} K{sup +} {Lambda}(1405) with high statistics and over different {Sigma}{pi} decay channels. The reconstructed invariant mass distribution (lineshape) has been measured, as well as the differential cross sections for the {Lambda}(1405), {Sigma}(1385), and {Lambda}(1520). Our analysis method is discussed and our near-final results for the {Lambda}(1405) lineshape and differential cross section are presented.

  19. Lineshape of the Lambda(1405) measured at CLAS

    SciTech Connect

    Kei Moriya, Reinhard Schumacher, CLAS Collaboration

    2012-04-01

    The {Lambda}(1405) has been a subject of controversy for decades, and its nature as a hyperon resonance has yet to be established firmly. Its peculiar lineshape, i.e., its {Sigma}{pi} invariant mass spectrum has lead to various theoretical studies, and some of these show that it may possess strong dynamical components which are not seen in other well-known baryons. With the CLAS detector system in Hall B at Jefferson Lab, we have measured the photoproduction reaction {gamma} + p {yields} K{sup +} {Lambda}(1405) with high statistics over different {Sigma}{pi} decay channels. The reconstructed invariant mass distribution has been measured, as well as the differential cross sections for the nearby {Lambda}(1405), {Sigma}(1385), and {Lambda}(1520). Our analysis method is discussed and our near-final results for the {Lambda}(1405) lineshape is presented.

  20. Simple model for lambda-doublet propensities in bimolecular reactions

    NASA Technical Reports Server (NTRS)

    Bronikowski, Michael J.; Zare, Richard N.

    1990-01-01

    A simple geometric model is presented to account for lambda-doublet propensities in bimolecular reactions A + BC - AB + C. It applies to reactions in which AB is formed in a pi state, and in which the unpaired molecular orbital responsible for lambda-doubling arises from breaking the B-C bond. The lambda-doublet population ratio is predicted to be 2:1 provided that: (1) the motion of A in the transition state determines the plane of rotation of AB; (2) the unpaired pi orbital lying initially along the B-C bond may be resolved into a projection onto the AB plane of rotation and a projection perpendicular to this plane; (3) there is no preferred geometry for dissociation of ABC. The 2:1 lambda-doublet ratio is the 'unconstrained dynamics prior' lambda-doublet distribution for such reactions.

  1. High Resolution Spectroscopy of 16N_Lambda by Electroproduction

    SciTech Connect

    Cusanno, Francesco; Urciuoli, Guido; Acha Quimper, Armando; Ambrozewicz, Pawel; Aniol, Konrad; Baturin, Pavlo; Bertin, Pierre; Benaoum, Hachemi; Blomqvist, Ingvar; Boeglin, Werner; Breuer, Herbert; Brindza, Paul; Bydzovsky, Petr; Camsonne, Alexandre; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chen, Jian-Ping; Choi, Seonho; Chudakov, Eugene; Cisbani, Evaristo; Colilli, Stefano; Coman, Luminita; Craver, Brandon; de Cataldo, Giacinto; De Jager, Cornelis; De Leo, Raffaele; Deur, Alexandre; Ferdi, Catherine; Feuerbach, Robert; Folts, Edward; Frullani, Salvatore; Garibaldi, Franco; Gayou, Olivier; Giuliani, Fausto; Gomez, Javier; Gricia, Massimo; Hansen, Jens-Ole; Hayes, David; Higinbotham, Douglas; Holmstrom, Timothy; Hyde, Charles; Ibrahim, Hassan; Iodice, Mauro; Jiang, Xiaodong; Kaufman, Lisa; Kino, Kouichi; Kross, Brian; Lagamba, Luigi; LeRose, John; Lindgren, Richard; Lucentini, Maurizio; Margaziotis, Demetrius; Markowitz, Pete; Marrone, Stefano; Meziani, Zein-Eddine; McCormick, Kathy; Michaels, Robert; Millener, D.; Miyoshi, Toshinobu; Moffit, Bryan; Monaghan, Peter; Moteabbed, Maryam; Munoz Camacho, Carlos; Nanda, Sirish; Nappi, E.; Nelyubin, Vladimir; Norum, Blaine; Okasyasu, Y.; Paschke, Kent; Perdrisat, Charles; Piasetzky, Eliazer; Punjabi, Vina; Qiang, Yi; Raue, Brian; Reimer, Paul; Reinhold, Joerg; Reitz, Bodo; Roche, Rikki; Rodriguez, Victor; Saha, Arunava; Santavenere, Fabio; Sarty, Adam; Segal, John; Shahinyan, Albert; Singh, Jaideep; Sirca, Simon; Snyder, Ryan; Solvignon, Patricia; Sotona, M.; Sotona, Miloslav; Sotona, M.; Sotona, Miloslav; Sotona, M.; Sotona, Miloslav; Sotona, M.; Sotona, Miloslav; Subedi, Ramesh; Sulkosky, Vince; Sulkosky, Vincent; Sulkosky, Vince; Sulkosky, Vincent; Suzuki, Tomokazu; Ueno, Hiroaki; Ulmer, Paul; Veneroni, P.P.; Voutier, Eric; Wojtsekhowski, Bogdan; Zeng, X.; Zorn, Carl

    2009-01-01

    An experimental study of the 16O(e, e'K+)16N_Lambda reaction has been performed at Jefferson Lab. A thin film of falling water was used as a target. This permitted a simultaneous measurement of the p(e, e'K+)Lambda,Sigma_0 exclusive reactions and a precise calibration of the energy scale. A ground-state binding energy of 13.76 ± 0.16 MeV was obtained for 16N_Lambda with better precision than previous measurements on the mirror hypernucleus 16O_Lambda. Precise energies have been determined for peaks arising from a Lambda in s and p orbits coupled to the p1/2 and p3/2 hole states of the 15N core nucleus.

  2. Is there a {pi}{lambda}N bound state?

    SciTech Connect

    Gal, A.; Garcilazo, H.

    2008-07-01

    We have searched for bound states in the {pi}{lambda}N system by solving the nonrelativistic Faddeev equations, as well as a relativistic version, with input separable {pi}N, {pi}{lambda}, and {lambda}N interactions. A bound-state solution, driven by the {delta}(1232) and the {sigma}(1385) p-wave meson-baryon resonances, was found in the channel (I,J{sup P})=((3/2),2{sup +}), provided the {lambda} laboratory momentum at which the {lambda}N {sup 3}S{sub 1} phase shift becomes negative is larger than p{sub lab}{approx}750-800 MeV/c. Other strange and charmed {pi}BB{sup '} systems that might have bound states of a similar nature are listed.

  3. Comments on \\Lambda and other repelling equations of state

    NASA Astrophysics Data System (ADS)

    Schulz, Hartmut

    DeSitter's (1917) cosmology of a universe devoid of matter but expanding due to a positive cosmological constant \\Lambda is commonly considered as a valid counterexample against a Machian interpretation of General Relativity. This view is conceptually questionable because of the mathematical equivalence of \\Lambda with a constant (`vacuum') energy density \\rho_{\\Lambda} (as e.g.\\ inflationists use it) implying an equation of state P=-\\rho_{\\Lambda} that leads to a `repelling force' in a standard universe. We discuss the reasons for this apparent antigravity extracted from the structure of the theory. Antigravitational effects can be produced by other equations of state as well, notably by proposed dark matter constituents. Such components plus matter and radiation lead to world models (we show examples) beyond the classical classification schemes for which we propose extensions in terms of `critical equations of state' rather than `critical \\Lambda'.

  4. Phillips' Lambda function: Data summary and physical model

    NASA Astrophysics Data System (ADS)

    Irisov, V.; Plant, W.

    2016-03-01

    Measurements of Phillips' Lambda function describing the average length of breakers on the ocean per unit area at speed cb are summarized. An expression is developed that fits these data within reasonable bounds. A physical model for the Lambda function is derived based on the assumption that breaking occurs when the surface steepness exceeds a threshold value. The energy contained in the breaking region is related to the fifth power of the breaker speed, as Phillips showed, and from this the probability of finding a breaker with a speed cb may be determined from a simulation of the long-wave surface based on a linear superposition of Fourier components. This probability is directly related to the Lambda function so that a form for this function can be determined. The Lambda function so determined agrees in both shape and intensity with the fit to the measured Lambda functions.

  5. High-resolution spectroscopy of Lambda16N by electroproduction.

    PubMed

    Cusanno, F; Urciuoli, G M; Acha, A; Ambrozewicz, P; Aniol, K A; Baturin, P; Bertin, P Y; Benaoum, H; Blomqvist, K I; Boeglin, W U; Breuer, H; Brindza, P; Bydzovský, P; Camsonne, A; Chang, C C; Chen, J-P; Choi, Seonho; Chudakov, E A; Cisbani, E; Colilli, S; Coman, L; Craver, B J; De Cataldo, G; de Jager, C W; De Leo, R; Deur, A P; Ferdi, C; Feuerbach, R J; Folts, E; Fratoni, R; Frullani, S; Garibaldi, F; Gayou, O; Giuliani, F; Gomez, J; Gricia, M; Hansen, J O; Hayes, D; Higinbotham, D W; Holmstrom, T K; Hyde, C E; Ibrahim, H F; Iodice, M; Jiang, X; Kaufman, L J; Kino, K; Kross, B; Lagamba, L; LeRose, J J; Lindgren, R A; Lucentini, M; Margaziotis, D J; Markowitz, P; Marrone, S; Meziani, Z E; McCormick, K; Michaels, R W; Millener, D J; Miyoshi, T; Moffit, B; Monaghan, P A; Moteabbed, M; Muñoz Camacho, C; Nanda, S; Nappi, E; Nelyubin, V V; Norum, B E; Okasyasu, Y; Paschke, K D; Perdrisat, C F; Piasetzky, E; Punjabi, V A; Qiang, Y; Raue, B; Reimer, P E; Reinhold, J; Reitz, B; Roche, R E; Rodriguez, V M; Saha, A; Santavenere, F; Sarty, A J; Segal, J; Shahinyan, A; Singh, J; Sirca, S; Snyder, R; Solvignon, P H; Sotona, M; Subedi, R; Sulkosky, V A; Suzuki, T; Ueno, H; Ulmer, P E; Veneroni, P; Voutier, E; Wojtsekhowski, B B; Zheng, X; Zorn, C

    2009-11-13

    An experimental study of the (16)O(e,e'K(+))(Lambda)(16)N reaction has been performed at Jefferson Lab. A thin film of falling water was used as a target. This permitted a simultaneous measurement of the p(e,e'K(+))Lambda, Sigma(0) exclusive reactions and a precise calibration of the energy scale. A ground-state binding energy of 13.76+/-0.16 MeV was obtained for (Lambda)(16)N with better precision than previous measurements on the mirror hypernucleus (Lambda)(16)O. Precise energies have been determined for peaks arising from a Lambda in s and p orbits coupled to the p(1/2) and p(3/2) hole states of the (15)N core nucleus. PMID:20365979

  6. Tertiary structure of human {Lambda}6 light chains.

    SciTech Connect

    Pokkuluri, P. R.; Solomon, A.; Weiss, D. T.; Stevens, F. J.; Schiffer, M.; Center for Mechanistic Biology and Biotechnology; Univ. of Tennessee Medical Center /Graduate School of Medicine

    1999-01-01

    AL amyloidosis is a disease process characterized by the pathologic deposition of monoclonal light chains in tissue. To date, only limited information has been obtained on the molecular features that render such light chains amyloidogenic. Although protein products of the major human V kappa and V lambda gene families have been identified in AL deposits, one particular subgroup--lambda 6--has been found to be preferentially associated with this disease. Notably, the variable region of lambda 6 proteins (V lambda 6) has distinctive primary structural features including the presence in the third framework region (FR3) of two additional amino acid residues that distinguish members of this subgroup from other types of light chains. However, the structural consequences of these alterations have not been elucidated. To determine if lambda 6 proteins possess unique tertiary structural features, as compared to light chains of other V lambda subgroups, we have obtained x-ray diffraction data on crystals prepared from two recombinant V lambda 6 molecules. These components, isolated from a bacterial expression system, were generated from lambda 6-related cDNAs cloned from bone marrow-derived plasma cells from a patient (Wil) who had documented AL amyloidosis and another (Jto) with multiple myeloma and tubular cast nephropathy, but no evident fibrillar deposits. The x-ray crystallographic analyses revealed that the two-residue insertion located between positions 68 and 69 (not between 66 and 67 as previously surmised) extended an existing loop region that effectively increased the surface area adjacent to the first complementarity determining region (CDR1). Further, an unusual interaction between the Arg 25 and Phe 2 residues commonly found in lambda 6 molecules was noted. However, the structures of V lambda 6 Wil and Jto also differed from each other, as evidenced by the presence in the latter of certain ionic and hydrophobic interactions that we posit increased protein

  7. Measurement of the production fraction times branching fraction $\\boldsymbol{ f(b\\to\\Lambda_{b})\\cdot \\mathcal{B}(\\Lambda_{b}\\to J/\\psi \\Lambda)}$

    SciTech Connect

    Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Alexeev, Guennadi D.; Alkhazov, Georgiy D.; Alton, Andrew K.; Alverson, George O.; Alves, Gilvan Augusto; Ancu, Lucian Stefan; /Nijmegen U. /Fermilab

    2011-05-01

    The {Lambda}{sub b}(udb) baryon is observed in the decay {Lambda}{sub b} {yields} J/{psi}{Lambda} using 6.1 fb{sup -1} of p{bar p} collisions collected with the D0 detector at {radical}s = 1.96 TeV. The production fraction multiplied by the branching fraction for this decay relative to that for the decay B{sup 0} {yields} J/{psi}K{sub s}{sup 0} is measured to be 0.345 {+-} 0.034 (stat.) {+-} 0.033 (syst.) {+-} 0.003 (PDG). Using the world average value of f(b {yields} B{sup 0}) {center_dot} {Beta}(B{sup 0} {yields} J/{psi}K{sub s}{sup 0}) = (1.74 {+-} 0.08) x 10{sup -5}, they obtain f(b {yields} {Lambda}{sub b}) {center_dot} {Beta}({Lambda}{sub b} {yields} J/{psi}{Lambda}) = (6.01 {+-} 0.60 (stat.) {+-} 0.58 (syst.) {+-} 0.28 (PDG)) x 10{sup -5}. This measurement represents an improvement in precision by about a factor of three with respect to the current world average.

  8. Doublet-spacing enhancement caused by {Lambda}N-{Sigma}N coupling in {sub {Lambda}L}i hypernuclear isotopes

    SciTech Connect

    Umeya, Atsushi; Harada, Toru

    2011-03-15

    We theoretically investigate energy spacings of doublets in {sub {Lambda}L}i hypernuclear isotopes with A=7-10 in shell-model calculations with a {Lambda}N-{Sigma}N coupling effect. The calculated results show that the energy shifts are {Delta}{epsilon}=0.09-0.28 MeV and the {Sigma}-mixing probabilities are P{sub {Sigma}}=0.10%-0.34% in {Lambda} ground states for the isotopes because of the {Lambda}N-{Sigma}N coupling in the first-order perturbation. It is found that the energy spacing of the doublet is enhanced as a neutron number N increases; the contribution of the {Lambda}N-{Sigma}N coupling interaction is comparable to that of the {Lambda}N interaction in the neutron-rich {Lambda} hypernuclei. The coherent mechanism of this doublet-spacing enhancement is also discussed in terms of Fermi-type and Gamow-Teller-type {Lambda}N-{Sigma}N couplings.

  9. Hepatopancreatic intoxication of lambda cyhalothrin insecticide on albino rats

    PubMed Central

    Elhalwagy, Manal EA; Abd-Alrahman, Sherif H; Nahas, AA; Ziada, Reem M; Mohamady, Aziza H

    2015-01-01

    Background: Despite the known adverse effects of lambda cyhalothrin insecticide, little is known about its hepatopancreatic intoxication effects. The present study was carried out to elucidate sub-chronic effect of Karat 2.5% EC formulation of lambda cyhalothrin on male albino rats. Methods: To explore the effects of exposure to lambda cyhalothrin on rats and its mechanism, low (1/40 of LD50, 5 mg/kg/day) and high dose (1/4 of LD50, 50 mg/kg/day) lambda cyhalothrin were applied to rats via drinking water for 3 months. Blood samples were collected monthly, and the animals were dissected for liver and pancreas’s examination at the end of the experiment. Lambda cyhalothrin administration was associated with the elevation in lipid peroxidation marker, malondialdehyde (MDA), reduction in SH-protein a major marker for antioxidant, as well as basel paraoxonase (PON) in both treated groups throughout the experimental periods. Results: In addition, significant elevations in liver enzymes alanin amino transferase, (ALT), and aspartate amino transferase (AST), as well as plasma acetylcholinesterase (AChE) and glucose level. While, significant reduction in insulin level through the experimental periods. Results of histopathological and histochemical studies showed that lambda cyhalothrin exposure induces liver and pancreatic tissues damage and depletion in glycogen content was pronounced in liver of both treated groups. Conclusions: In conclusion subchronic intoxication with lambda cyhalothrin formulation induced remarkable changes in the examined parameters. PMID:26221269

  10. Lambda Probe Measurements of Laboratory Spheromaks

    NASA Astrophysics Data System (ADS)

    Jorne, E.; Bellan, P. M.; Hsu, S. C.; Moynihan, C.

    2003-10-01

    A combined current and magnetic probe (lambda probe) has been constructed and is being tested for the purpose of investigating the behavior of spheromaks formed by the Caltech planar spheromak gun. The probe consists of a 1.5cm diameter, 52 turn Rogowski coil and a single loop magnetic coil, housed in a ceramic shell attached to a 95cm long hollow, steel shaft. A high voltage power supply was used to test the probe's ability to measure pulsed currents with submicrosecond rise times. A calibrated current pulse was provided by a 1μF capacitor discharged by a krytron switch to a low inductance circuit. Magnetic calibration was obtained by using the capacitor bank to power a 16cm diameter Helmholtz coil. Both magnetic and current calibration were in good agreement with estimates based on geometry. An existing steel shaft will be replaced by a ceramic shaft in order to minimize undesired effects on the plasma by a conductor. Once sealed with epoxy, the probe will be ready for insertion into the vacuum chamber and used to measure the magnetic field and parallel current during spheromak formation.

  11. Acoustics of the Lambda Transition in Superfluid Helium

    NASA Astrophysics Data System (ADS)

    Megson, Peter; Meichle, David; Lathrop, Daniel

    2014-11-01

    Liquid Helium undergoes a phase transition and becomes a quantum superfluid when cooled below the Lambda transition temperature of 2.17 Kelvin. The superfluid, which is a partial Bose Einstein Condensate, exhibits unique macroscopic properties such as flow without viscosity and ballistic temperature propagation. We have recorded striking audio-frequency sounds using a micro electromechanical microphone (MEMS) present as the Helium goes through the Lambda transition. Characterization of this sound, as well as its relevance to theories of the Lambda transition will be presented.

  12. High resolution spectroscopy of (lambda)(12)B by electroproduction.

    PubMed

    Iodice, M; Cusanno, F; Acha, A; Ambrozewicz, P; Aniol, K A; Baturin, P; Bertin, P Y; Benaoum, H; Blomqvist, K I; Boeglin, W U; Breuer, H; Brindza, P; Bydzovský, P; Camsonne, A; Chang, C C; Chen, J-P; Choi, Seonho; Chudakov, E A; Cisbani, E; Colilli, S; Coman, L; Craver, B J; De Cataldo, G; de Jager, C W; De Leo, R; Deur, A P; Ferdi, C; Feuerbach, R J; Folts, E; Fratoni, R; Frullani, S; Garibaldi, F; Gayou, O; Giulani, F; Gomez, J; Gricia, M; Hansen, J O; Hayes, D; Higinbotham, D W; Holmstrom, T K; Hyde, C E; Ibrahim, H F; Jiang, X; Kaufman, L J; Kino, K; Kross, B; Lagamba, L; LeRose, J J; Lindgren, R A; Lucentini, M; Margaziotis, D J; Markowitz, P; Marrone, S; Meziani, Z E; McCormick, K; Michaels, R W; Millener, D J; Miyoshi, T; Moffit, B; Monaghan, P A; Moteabbed, M; Muñoz Camacho, C; Nanda, S; Nappi, E; Nelyubin, V V; Norum, B E; Okasyasu, Y; Paschke, K D; Perdrisat, C F; Piasetzky, E; Punjabi, V A; Qiang, Y; Raue, B; Reimer, P E; Reinhold, J; Reitz, B; Roche, R E; Rodriguez, V M; Saha, A; Santavenere, F; Sarty, A J; Segal, J; Shahinyan, A; Singh, J; Sirca, S; Snyder, R; Solvignon, P H; Sotona, M; Subedi, R; Sulkosky, V A; Suzuki, T; Ueno, H; Ulmer, P E; Urciuoli, G M; Veneroni, P; Voutier, E; Wojtsekhowski, B B; Ye, Y; Zheng, X; Zhou, S; Zorn, C

    2007-08-01

    An experiment measuring electroproduction of hypernuclei has been performed in hall A at Jefferson Lab on a 12C target. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring imaging Cherenkov detector were added to the hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Thus, the observed (Lambda)(12)B spectrum shows for the first time identifiable strength in the core-excited region between the ground-state s-wave Lambda peak and the 11 MeV p-wave Lambda peak. PMID:17930747

  13. DYNAMICS OF PLANETARY SYSTEMS IN STAR CLUSTERS

    SciTech Connect

    Spurzem, R.; Giersz, M.; Heggie, D. C.; Lin, D. N. C.

    2009-05-20

    At least 10%-15% of nearby Sunlike stars have known Jupiter-mass planets. In contrast, very few planets are found in mature open and globular clusters such as the Hyades and 47 Tuc. We explore here the possibility that this dichotomy is due to the postformation disruption of planetary systems associated with the stellar encounters in long-lived clusters. One supporting piece of evidence for this scenario is the discovery of freely floating low-mass objects in star forming regions. We use two independent numerical approaches, a hybrid Monte Carlo and a direct N-body method, to simulate the impact of the encounters. We show that the results of numerical simulations are in reasonable agreement with analytical determinations in the adiabatic and impulsive limits. They indicate that distant stellar encounters generally do not significantly modify the compact and nearly circular orbits. However, moderately close stellar encounters, which are likely to occur in dense clusters, can excite planets' orbital eccentricity and induce dynamical instability in systems that are closely packed with multiple planets. The disruption of planetary systems occurs primarily through occasional nearly parabolic, nonadiabatic encounters, though eccentricity of the planets evolves through repeated hyperbolic adiabatic encounters that accumulate small-amplitude changes. The detached planets are generally retained by the potential of their host clusters as free floaters in young stellar clusters such as {sigma} Orionis. We compute effective cross sections for the dissolution of planetary systems and show that, for all initial eccentricities, dissolution occurs on timescales that are longer than the dispersion of small stellar associations, but shorter than the age of typical open and globular clusters. Although it is much more difficult to disrupt short-period planets, close encounters can excite modest eccentricity among them, such that subsequent tidal dissipation leads to orbital decay

  14. Observation of the Baryonic B decay B0bar to Lambda_c^+ anti-Lambda K-

    SciTech Connect

    Lees, J.P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Milanes, D.A.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Brown, D.N.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Koch, H.; Schroeder, T.; Asgeirsson, D.J.; Hearty, C.; Mattison, T.S.; /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /Genoa U. /INFN, Genoa /Genoa U. /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /Indian Inst. Tech., Guwahati /Harvard U. /Harvey Mudd Coll. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U., Comp. Sci. Dept. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /INFN, Milan /Milan U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /INFN, Milan /Milan U. /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /INFN, Naples /Naples U. /INFN, Naples /Naples U. /INFN, Naples /Naples U. /INFN, Naples /Naples U. /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /Padua U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /INFN, Padua /INFN, Padua /Padua U. /INFN, Padua /Padua U. /Paris U., VI-VII /INFN, Perugia /Perugia U. /INFN, Perugia /Perugia U. /INFN, Perugia /Perugia U. /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa U. /Sassari U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa U. /INFN, Pisa /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Southern Methodist U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas U. /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /INFN, Trieste /Trieste U. /Valencia U., IFIC /Victoria U. /Warwick U. /Wisconsin U., Madison

    2011-11-08

    The authors report the observation of the baryonic B decay {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +} {bar {Lambda}}K{sup -} with a significance larger than 7 standard deviations based on 471 x 10{sup 6} B{bar B} pairs collected with the BABAR detector at the PEP-II storage ring at SLAC. They measure the branching fraction for the decay {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +} {bar {Lambda}}K{sup -} to be (3.8 {+-} 0.8{sub stat} {+-} 0.2{sub sys} {+-} 1.0 {sub {Lambda}{sub c}{sup +}}) x 10{sup -5}. The uncertainties are statistical, systematic, and due to the uncertainty in the {Lambda}{sub c}{sup +} branching fraction. They find that the {Lambda}{sub c}{sup +} K{sup -} invariant mass distribution shows an enhancement above 3.5 GeV/c{sup 2}.

  15. RESOLVING THE GAP AND AU-SCALE ASYMMETRIES IN THE PRE-TRANSITIONAL DISK OF V1247 ORIONIS

    SciTech Connect

    Kraus, Stefan; Espaillat, Catherine; Wilner, David J.; Ireland, Michael J.; Sitko, Michael L.; Swearingen, Jeremy R.; Werren, Chelsea; Monnier, John D.; Calvet, Nuria; Grady, Carol A.; Harries, Tim J.; Hoenig, Sebastian F.; Russell, Ray W.

    2013-05-01

    Pre-transitional disks are protoplanetary disks with a gapped disk structure, potentially indicating the presence of young planets in these systems. In order to explore the structure of these objects and their gap-opening mechanism, we observed the pre-transitional disk V1247 Orionis using the Very Large Telescope Interferometer, the Keck Interferometer, Keck-II, Gemini South, and IRTF. This allows us to spatially resolve the AU-scale disk structure from near- to mid-infrared wavelengths (1.5-13 {mu}m), tracing material at different temperatures and over a wide range of stellocentric radii. Our observations reveal a narrow, optically thick inner-disk component (located at 0.18 AU from the star) that is separated from the optically thick outer disk (radii {approx}> 46 AU), providing unambiguous evidence for the existence of a gap in this pre-transitional disk. Surprisingly, we find that the gap region is filled with significant amounts of optically thin material with a carbon-dominated dust mineralogy. The presence of this optically thin gap material cannot be deduced solely from the spectral energy distribution, yet it is the dominant contributor at mid-infrared wavelengths. Furthermore, using Keck/NIRC2 aperture masking observations in the H, K', and L' bands, we detect asymmetries in the brightness distribution on scales of {approx}15-40 AU, i.e., within the gap region. The detected asymmetries are highly significant, yet their amplitude and direction changes with wavelength, which is not consistent with a companion interpretation but indicates an inhomogeneous distribution of the gap material. We interpret this as strong evidence for the presence of complex density structures, possibly reflecting the dynamical interaction of the disk material with sub-stellar mass bodies that are responsible for the gap clearing.

  16. Variations of the high-level Balmer line spectrum of the helium-strong star σ Orionis E

    NASA Astrophysics Data System (ADS)

    Smith, M. A.; Bohlender, D. A.

    2007-12-01

    Using the high-level Balmer lines and continuum, we trace the density structure of two magnetospheric disk segments of the prototypical Bp star σ Orionis E (B2p) as these segments occult portions of the star during the rotational cycle. High-resolution spectra of the Balmer lines ≥H9 and Balmer edge were obtained on seven nights in January-February 2007 at an average sampling of 0.01 cycles. We measured equivalent width variations due to the star occultations by two disk segments 0.4 cycles apart and constructed differential spectra of the migrations of the corresponding absorptions across the Balmer line profiles. We first estimated the rotational and magnetic obliquity angles. We then simulated the observed Balmer jump variation using the model atmosphere codes synspec/circus and evaluated the disk geometry and gas thermodynamics. We find that the two occultations are caused by two disk segments. The first of these transits quickly, indicating that the segment resides in a range of distances, perhaps 2.5-6 R*, from the star. The second consists of a more slowly moving segment situated closer to the surface and causing two semi-resolved absorbing maxima. During its transit this segment brushes across the star's “lower” limb. Judging from the line visibility up to H23-H24 during the occultations, both disk segments have mean densities near 1012 cm-3 and are opaque in the lines and continuum. They have semiheights less than 1/2 R*, and their temperatures are near 10 500 K and 12 000 K, respectively. In all, the disks of Bp stars have a much more complicated geometry than has been anticipated, as evidenced by their (sometimes) non-coplanarity, de-centerness, and from star to star, differences in disk height. Based on observations obtained at the the Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada.

  17. Photometric properties for selected Algol-type binaries. VI. The newly discovered oEA star FR Orionis

    SciTech Connect

    Yang, Y.-G.; Wei, J.-Y.; Li, H.-L.

    2014-02-01

    New photometry of the neglected eclipsing binary FR Orionis was obtained in 2012 November and December. Using the updated Wilson-Devinney program, the photometric elements were deduced from two-color light curves. The results indicate that this system is a semi-detached binary, with a mass ratio of 0.325(± 0.002) and a fill-out factor of the primary of f{sub p} = 73.5(± 0.2)%. The oscillating light curves imply that FR Ori may be an oscillating EA (oEA)-type star with a rapidly pulsating, mass-accreting primary component. After we removed the theoretical light curves from the observations, Fourier analysis revealed that the more massive component possibly shows a δ Scuti type pulsation with four detected frequencies. The dominant frequency is f {sub 1} = 38.6c day{sup –1} (i.e., P {sub puls} = 37.3 minutes), and the pulsation constant is Q = 0.014 days. Based on all available eclipsing times, the orbital period is undergoing a secular period increase with a rate of dP/dt = +8.85(±0.66) × 10{sup –8} day yr {sup –1}, which may be interpreted by mass transfer from the secondary to the primary. We expect that the more massive component will fill its Roche lobe due to mass transfer of the secondary. Therefore, the oEA star FR Ori may evolve into a contact configuration.

  18. Suppression of the {Lambda}-{Sigma} coupling in nuclear matter

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.

    1995-08-01

    We initiated a study of the modification of the coupling of the {Lambda}N to the {Sigma}N channel in nuclear matter with the Fermi hypernetted-chain variational approach. This modification of the {Lambda}N-{Sigma}N coupling is a central problem in hypernuclear physics and is related closely to the strongly repulsive three-body forces which are needed to account for hypernuclear binding energies. All earlier calculations have only considered this problem in the so-called G-matrix approximation which neglects important higher-order effects. An important result of this work will be a better understanding of the density dependence of {Lambda} binding in nuclear matter, which can then be tested in the calculation of the {Lambda} single-particle energies.

  19. The chemical composition of the Lambda Bootis stars

    NASA Technical Reports Server (NTRS)

    Baschek, B.; Slettebak, A.

    1988-01-01

    Measurements of the equivalent widths of 24 ultraviolet lines from IUE spectra of 10 Lambda Bootis or suspected Lambda Bootis stars and 19 normal standard stars of spectral types B8-A7 have been compared with line strengths determined using model atmospheres. Abundance differences are estimated via a differential analysis technique. It is found that the ratio of C, N, and O to the heavier elements Mg to Ni is significantly larger than that for solar composition stars.

  20. A high statistics measurement of the Lambda(+)(c) lifetime.

    PubMed

    Link, J M; Reyes, M; Yager, P M; Anjos, J C; Bediaga, I; Göbel, C; Magnin, J; Massafferi, A; de Miranda, J M; Pepe, I M; dos Reis, A C; Carrillo, S; Casimiro, E; Cuautle, E; Sánchez-Hernández, A; Uribe, C; Vazquez, F; Agostino, L; Cinquini, L; Cumalat, J P; O'Reilly, B; Ramirez, J E; Segoni, I; Butler, J N; Cheung, H W K; Gaines, I; Garbincius, P H; Garren, L A; Gottschalk, E; Kasper, P H; Kreymer, A E; Kutschke, R; Bianco, S; Fabbri, F L; Zallo, A; Cawlfield, C; Kim, D Y; Rahimi, A; Wiss, J; Gardner, R; Kryemadhi, A; Chung, Y S; Kang, J S; Ko, B R; Kwak, J W; Lee, K B; Park, H; Alimonti, G; Boschini, M; D'Angelo, P; DiCorato, M; Dini, P; Giammarchi, M; Inzani, P; Leveraro, F; Malvezzi, S; Menasce, D; Mezzadri, M; Milazzo, L; Moroni, L; Pedrini, D; Pontoglio, C; Prelz, F; Rovere, M; Sala, S; Davenport, T F; Arena, V; Boca, G; Bonomi, G; Gianini, G; Liguori, G; Merlo, M M; Pantea, D; Ratti, S P; Riccardi, C; Vitulo, P; Hernandez, H; Lopez, A M; Luiggi, E; Mendez, H; Mendez, L; Mirles, A; Montiel, E; Olaya, D; Paris, A; Quinones, J; Rivera, C; Xiong, W; Zhang, Y; Wilson, J R; Cho, K; Handler, T; Mitchell, R; Engh, D; Hosack, M; Johns, W E; Nehring, M; Sheldon, P D; Stenson, K; Vaandering, E W; Webster, M; Sheaff, M

    2002-04-22

    A high statistics measurement of the Lambda(+)(c) lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat) +/- 2.5 (syst) fs from 8034 +/- 122 Lambda(+)(c)-->pK(-)pi(+) decays represents a significant improvement over the present world average. PMID:11955226

  1. Absorption of {Lambda}(1520) hyperons in photon-nucleus collisions

    SciTech Connect

    Paryev, E. Ya.

    2012-12-15

    In the framework of the nuclear spectral function approach for incoherent primary photon-nucleon and secondary pion-nucleon production processes we study the inclusive {Lambda}(1520)-hyperon production in the interaction of 2-GeV photons with nuclei. In particular, the A and momentum dependences of the absolute and relative {Lambda}(1520)-hyperon yields are investigated in two scenarios for its in-medium width. Our model calculations show that the pion-nucleon production channel contributes appreciably to the {Lambda}(1520) creation at intermediate momenta both in light and heavy nuclei in the chosen kinematics and, hence, has to be taken into consideration on close examination of the dependences of the {Lambda}(1520)-hyperon yields on the target mass number with the aim to get information on its width in the medium. They also demonstrate that the A and momentum dependences of the absolute and relative {Lambda}(1520)-hyperon production cross sections at incident energy of interest are markedly sensitive to the {Lambda}(1520) in-medium width, which means that these observables may be an important tool to determine the above width.

  2. The Assembly of Galaxy Clusters

    SciTech Connect

    Berrier, Joel C.; Stewart, Kyle R.; Bullock, James S.; Purcell, Chris W.; Barton, Elizabeth J.; Wechsler, Risa H.

    2008-05-16

    We study the formation of fifty-three galaxy cluster-size dark matter halos (M = 10{sup 14.0-14.76} M{sub {circle_dot}}) formed within a pair of cosmological {Lambda}CDM N-body simulations, and track the accretion histories of cluster subhalos with masses large enough to host {approx} 0.1L{sub *} galaxies. By associating subhalos with cluster galaxies, we find the majority of galaxies in clusters experience no 'pre-processing' in the group environment prior to their accretion into the cluster. On average, {approx} 70% of cluster galaxies fall into the cluster potential directly from the field, with no luminous companions in their host halos at the time of accretion; and less than {approx} 12% are accreted as members of groups with five or more galaxies. Moreover, we find that cluster galaxies are significantly less likely to have experienced a merger in the recent past ({approx}< 6 Gyr) than a field halo of the same mass. These results suggest that local, cluster processes like ram-pressure stripping, galaxy harassment, or strangulation play the dominant role in explaining the difference between cluster and field populations at a fixed stellar mass; and that pre-evolution or past merging in the group environment is of secondary importance for setting cluster galaxy properties for most clusters. The accretion times for z = 0 cluster members are quite extended, with {approx} 20% incorporated into the cluster halo more than 7 Gyr ago and {approx} 20% within the last 2 Gyr. By comparing the observed morphological fractions in cluster and field populations, we estimate an approximate time-scale for late-type to early-type transformation within the cluster environment to be {approx} 6 Gyr.

  3. {lambda}-Polarization Measurement in {pi}-p{yields}K0{lambda} in the Framework of 'EPECUR' Experiment Proposal

    SciTech Connect

    Alekseev, I. G.; Budkovsky, P. E.; Kanavets, V. P.; Kats, M. M.; Koroleva, L. I.; Kulikov, V. V.; Morozov, B. V.; Nesterov, V. M.; Ryltsov, V. V.; Sakharov, V. A.; Sulimov, A. D.; Svirida, D. N.; Filimonov, E. A.; Golubev, V. V.; Kovalev, A. I.; Kozlenko, N. G.; Kozlov, V. S.; Krivshich, A. G.; Novinsky, D. V.; Sumachev, V. V.

    2007-06-13

    The idea of 'EPECUR' was inspired by the recent splash of the activity around the pentaquark matters. The goal of the experiment is the search for narrow resonant states in the reactions {pi}-p {yields} {pi}-p and {pi}-p {yields} K0{lambda} based on the very precise cross section measurements in fine energy steps of 0.5 MeV in terms of the invariant mass. As a valuable byproduct of the second stage of the experiment, {lambda}-polarization in {pi}-p {yields} K0{lambda} can be measured, based on the well-known weak {lambda}-decay asymmetry. The expected statistical significance of the measurement overrides the best existing data from 'NIMROD' detector by an order of magnitude. The experimental setup is under construction at the ITEP proton synchrotron in collaboration with PNPI and ACU.

  4. Proton energy spectra in the nonmesonic weak decay of 12lambdaC and 28lambdaSi hypernuclei.

    PubMed

    Hashimoto, O; Ajimura, S; Aoki, K; Bhang, H; Hasegawa, T; Hotchi, H; Kim, Y D; Kishimoto, T; Maeda, K; Noumi, H; Ohta, Y; Omata, K; Outa, H; Park, H; Sato, Y; Sekimoto, M; Shibata, T; Takahashi, T; Youn, M

    2002-01-28

    Numbers of protons per Gamma hypernuclear weak decay were measured as a function of proton energy above 40 MeV, explicitly identifying production of Gamma hypernuclei by the (pi+,K+) reaction. The ratios between the neutron-stimulated to proton-stimulated nonmesonic decay widths, Gamma((Lambda)n-->nn)/Gamma((Lambda)p-->np) ( = Gamma(n)/Gamma(p)) were extracted by fitting the proton energy spectra. The present result claims that the proton yields are suppressed and the Gamma(n)/Gamma(p) ratios are close to 1 both for 12LambdaC and 28LambdaSi in contradiction to theoretical expectations based on meson exchange models. PMID:11801115

  5. Improved Measurement of the Form Factors in the Decay {lambda}{sub c}{sup +}{yields}{lambda}e{sup +}{nu}{sub e}

    SciTech Connect

    Hinson, J.W.; Huang, G.S.; Lee, J.; Miller, D.H.; Pavlunin, V.; Rangarajan, R.; Sanghi, B.; Shibata, E.I.; Shipsey, I.P.J.; Cronin-Hennessy, D.; Park, C.S.; Park, W.; Thayer, J.B.; Thorndike, E.H.; Coan, T.E.; Gao, Y.S.; Liu, F.; Stroynowski, R.; Artuso, M.; Boulahouache, C.

    2005-05-20

    Using the CLEO detector at the Cornell Electron Storage Ring, we have studied the distribution of kinematic variables in the decay {lambda}{sub c}{sup +}{yields}{lambda}e{sup +}{nu}{sub e}. By performing a four-dimensional maximum likelihood fit, we determine the form factor ratio, R=f{sub 2}/f{sub 1}=-0.31{+-}0.05(stat){+-}0.04(syst), the pole mass, M{sub pole}=[2.21{+-}0.08(stat){+-}0.14(syst)] GeV/c{sup 2}, and the decay asymmetry parameter of the {lambda}{sub c}{sup +}, {alpha}{sub {lambda}}{sub {sub c}}=-0.86{+-}0.03(stat){+-}0.02(syst), for =0.67 (GeV/c{sup 2}){sup 2}. We compare the angular distributions of the {lambda}{sub c}{sup +} and {lambda}{sub c}{sup -} and find no evidence for CP violation: A{sub {lambda}}{sub {sub c}}=(({alpha}{sub {lambda}}{sub {sub c}}+{alpha}{sub {lambda}}{sub {sub c}})/({alpha}{sub {lambda}}{sub {sub c}}-= {alpha}{sub {lambda}}{sub {sub c}}))=0.00{+-}0.03(stat){+-}0.01(syst){+-}0.02, where the third error is from the uncertainty in the world average of the CP-violating parameter, A{sub {lambda}}, for {lambda}{yields}p{pi}{sup -}.

  6. Non-LTE radiative transfer with lambda-acceleration - Convergence properties using exact full and diagonal lambda-operators

    NASA Technical Reports Server (NTRS)

    Macfarlane, J. J.

    1992-01-01

    We investigate the convergence properties of Lambda-acceleration methods for non-LTE radiative transfer problems in planar and spherical geometry. Matrix elements of the 'exact' A-operator are used to accelerate convergence to a solution in which both the radiative transfer and atomic rate equations are simultaneously satisfied. Convergence properties of two-level and multilevel atomic systems are investigated for methods using: (1) the complete Lambda-operator, and (2) the diagonal of the Lambda-operator. We find that the convergence properties for the method utilizing the complete Lambda-operator are significantly better than those of the diagonal Lambda-operator method, often reducing the number of iterations needed for convergence by a factor of between two and seven. However, the overall computational time required for large scale calculations - that is, those with many atomic levels and spatial zones - is typically a factor of a few larger for the complete Lambda-operator method, suggesting that the approach should be best applied to problems in which convergence is especially difficult.

  7. Measurement of the asymmetry parameter for the decay {Lambda}{yields}p{pi}{sup +}

    SciTech Connect

    Ablikim, M.; Bai, J. Z.; Bai, Y.; Cai, X.; Chen, H. S.; Chen, H. X.; Chen, J. C.; Chen, Jin; Chen, Y. B.; Chu, Y. P.; Deng, Z. Y.; Du, S. X.; Fang, J.; Fu, C. D.; Gao, C. S.; Gu, S. D.; Guo, Y. N.; He, K. L.; Heng, Y. K.; Hu, H. M.

    2010-01-01

    Based on a sample of 58x10{sup 6}J/{psi} decays collected with the BESII detector at the BEPC, the {Lambda} decay parameter {alpha}{sub {Lambda}}for {Lambda}{yields}p{pi}{sup +} is measured using about 9000 J/{psi}{yields}{Lambda}{Lambda}{yields}pp{pi}{sup +{pi}-} decays. A fit to the joint angular distributions yields {alpha}{sub {Lambda}({Lambda}{yields}p{pi}{sup +})}=-0.755{+-}0.083{+-}0.063, where the first error is statistical, and the second systematic.

  8. Ultraviolet Synthetic Spectra for Three Lambda Bootis Stars

    NASA Astrophysics Data System (ADS)

    Cheng, Kwang-Ping; Neff, James E.; Gray, Richard O.; Corbally, Christopher J.; Johnson, Dustin; Tarbell, Erik

    2015-01-01

    Lambda Boo-type stars are a group of late B to early F-type Population I dwarfs that show mild to extreme deficiencies of iron-peak elements (up to 2 dex), but their C, N, O, and S abundances are near solar. We show that the International Ultraviolet Explorer (IUE) spectra (1280-3200 A) of Lambda Bootis, 29 Cygni (a "confirmed" Lambda Boo star), and Vega (a "mild" Lambda Boo star) can be fit remarkably well by single-temperature synthetic spectra. We computed the full resolution synthetic ultraviolet (UV) spectrum covering the IUE wavelength range using Gray's Stellar Spectral Synthesis Program SPECTRUM. To improve the synthetic spectra, we generated a grid of LTE atmosphere models with the appropriate stellar parameters using ATLAS9 and the existing Castelli and Kurucz 2004 models. One of the improvements of their opacity distribution functions (ODFs) is the addition to the line blanketing near 1400 A and 1600 A by the quasi-molecular absorptions of atomic hydrogen undergoing collisions with protons and other neutral hydrogen atoms. New-ODF fluxes reproduce the ultraviolet observations of Lambda Boo stars in a more realistic way than previous computations. We also constructed our own UV line list for the relevant set of absorption features. Modeling the UV line spectra of Lambda Boo stars allows us to confirm their published surface abundances, including CNO and the iron group elements. It also provides further insight into their photospheric conditions (e.g., Teff, log g, [M/H], micro turbulent velocity, etc.). About 40 percent of the published Lambda Boo candidates have existing IUE spectra. We plan to follow this pilot study and perform UV spectral synthesis for all of them.

  9. Measurement of the branching fraction ${\\mathcal{B}}(\\Lambda^0_b\\rightarrow \\Lambda^+_c\\pi^-\\pi^+\\pi^-)$ at CDF

    SciTech Connect

    Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J.A.; Arisawa, T.; Artikov, A.; /Dubna, JINR /Texas A-M

    2011-12-01

    We report an analysis of the {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} decay in a data sample collected by the CDF II detector at the Fermilab Tevatron corresponding to 2.4 fb{sup -1} of integrated luminosity. We reconstruct the currently largest samples of the decay modes {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}(2595){sup +}{pi}{sup -} (with {Lambda}{sub c}(2595){sup +} {yields} {Lambda}{sub c}{sup +}{pi}{sup +}{pi}{sup -}), {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}(2625){sup +}{pi}{sup -} (with {Lambda}{sub c}(2625){sup +} {yields} {Lambda}{sub c}{sup +}{pi}{sup +}{pi}{sup -}), {Lambda}{sub b}{sup 0} {yields} {Sigma}{sub c}(2455){sup ++}{pi}{sup -}{pi}{sup -} (with {Sigma}{sub c}(2455){sup ++} {yields} {Lambda}{sub c}{sup +}{pi}{sup +}), and {Lambda}{sub b}{sup 0} {yields} {Sigma}{sub c}(2455)0{pi}{sup +}{pi}{sup -} (with {Sigma}{sub c}(2455)0 {yields} {Lambda}{sub c}{sup +}{pi}{sup -}) and measure the branching fractions relative to the {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -} branching fraction. We measure the ratio {Beta}({Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -})/ {Beta}({Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -})=3.04 {+-} 0.33(stat){sub -0.55}{sup +0.70}(syst) which is used to derive {Beta}({Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -})=(26.8{sub -11.2}{sup +11.9}) x 10{sup -3}.

  10. Tracing the young massive high-eccentricity binary system θ^1Orionis C through periastron passage

    NASA Astrophysics Data System (ADS)

    Kraus, S.; Weigelt, G.; Balega, Y. Y.; Docobo, J. A.; Hofmann, K.-H.; Preibisch, T.; Schertl, D.; Tamazian, V. S.; Driebe, T.; Ohnaka, K.; Petrov, R.; Schöller, M.; Smith, M.

    2009-04-01

    Context: The nearby high-mass star binary system θ^1Ori C is the brightest and most massive of the Trapezium OB stars at the core of the Orion Nebula Cluster, and it represents a perfect laboratory to determine the fundamental parameters of young hot stars and to constrain the distance of the Orion Trapezium Cluster. Aims: By tracing the orbital motion of the θ^1Ori C components, we aim to refine the dynamical orbit of this important binary system. Methods: Between January 2007 and March 2008, we observed θ^1Ori C with VLTI/AMBER near-infrared (H- and K-band) long-baseline interferometry, as well as with bispectrum speckle interferometry with the ESO 3.6 m and the BTA 6 m telescopes (B'- and V'-band). Combining AMBER data taken with three different 3-telescope array configurations, we reconstructed the first VLTI/AMBER closure-phase aperture synthesis image, showing the θ^1Ori C system with a resolution of ˜ 2 mas. To extract the astrometric data from our spectrally dispersed AMBER data, we employed a new algorithm, which fits the wavelength-differential visibility and closure phase modulations along the H- and K-band and is insensitive to calibration errors induced, for instance, by changing atmospheric conditions. Results: Our new astrometric measurements show that the companion has nearly completed one orbital revolution since its discovery in 1997. The derived orbital elements imply a short-period (P ≈ 11.3 yr) and high-eccentricity orbit (e ≈ 0.6) with periastron passage around 2002.6. The new orbit is consistent with recently published radial velocity measurements, from which we can also derive the first direct constraints on the mass ratio of the binary components. We employ various methods to derive the system mass (M_system = 44 ± 7 M⊙) and the dynamical distance (d = 410 ± 20 pc), which is in remarkably good agreement with recently published trigonometric parallax measurements obtained with radio interferometry. Based on observations made

  11. Integrative genomic analyses on interferon-lambdas and their roles in cancer prediction.

    PubMed

    Yang, Liming; Wei, Jifu; He, Shaoheng

    2010-02-01

    Interferon (IFN)-lambdas, including IFN-lambda1, IFN-lambda2, and IFN-lambda3, are a newly described group of cytokines distantly related to the type I IFNs and IL-10 family members. Besides the antiviral activity, IFN-lambdas were reported to inhibit various tumor growths in vitro and in vivo. Herein, we identified IFN-lambda genes from the genome sequences of the human, chimpanzee, macaque, orangutan, mouse, rat and dog, and found that the locations and copy of a specific IFN-lambda varied in different genomes, not just the copy of IFN-lambdas. We found human IFN-lambdas were expressed in fetal retina, fetal brain and T cells by ESTs search. Moreover, IFN-lambdas were also found to express in bladder cancer, blood cancer, breast cancer, glioma, head and neck cancer and lung cancer tissues. Three tumor-related transcriptional factors (steroidogenic factor-1, Wilms tumor 1 and P53) binding sites were identified within the 1.0-kb regions upstream of the transcriptional start site of human IFN-lambdas. Meta-analysis of the prognostic value of IFN-lambda genes in various cancers showed that the expression of IFN-lambdas are indeed related to the cancer prognosis in certain types of cancer. It can be predicted that IFN-lambdas take part in the cancer development by the regulation of expression of IFN-lambdas related to the SF-1, P53 and WT-1. PMID:20043142

  12. Measurements of the cosmological parameters {Omega} and {Lambda} from the first seven supernovae at z{ge}0.35

    SciTech Connect

    Perlmutter, S. |; Gabi, S. |; Goldhaber, G. |; Goobar, A. ||; Groom, D.E. |; Hook, I.M. |; Kim, A.G.; and others

    1997-07-01

    We have developed a technique to systematically discover and study high-redshift supernovae that can be used to measure the cosmological parameters. We report here results based on the initial seven of more than 28 supernovae discovered to date in the high-redshift supernova search of the Supernova Cosmology Project. We find an observational dispersion in peak magnitudes of {sigma}{sub M{sub B}}=0.27; this dispersion narrows to {sigma}M{sub B},corr=0.19 after correcting the magnitudes using the light-curve width-luminosity relation found for nearby (z{le}0.1) Type Ia supernovae from the Calan/Tololo survey (Hamuy et al.). Comparing light-curve width-corrected magnitudes as a function of redshift of our distant (z=0.35{endash}0.46) supernovae to those of nearby Type Ia supernovae yields a global measurement of the mass density, {Omega}{sub M}=0.88{sub {minus}0.60}{sup +0.69} for a {Lambda}=0 cosmology. For a spatially flat universe (i.e., {Omega}{sub M}+{Omega}{sub {Lambda}}=1) we find {Omega}{sub M}=0.94{sub {minus}0.28}{sup +0.34} or, equivalently, a measurement of the cosmological constant, {Omega}{sub {Lambda}}=0.06{sub {minus}0.34}{sup +0.28} ({lt}0.51 at the 95{percent} confidence level). For the more general Friedmann-Lemaitre cosmologies with independent {Omega}{sub M} and {Omega}{sub {Lambda}}, the results are presented as a confidence region on the {Omega}{sub M}{endash}{Omega}{sub {Lambda}} plane. This region does not correspond to a unique value of the deceleration parameter q{sub 0}. We present analyses and checks for statistical and systematic errors and also show that our results do not depend on the specifics of the width-luminosity correction. The results for {Omega}{sub {Lambda}}-versus-{Omega}{sub M} are inconsistent with {Lambda}-dominated, low-density, flat cosmologies that have been proposed to reconcile the ages of globular cluster stars with higher Hubble constant values. {copyright} {ital 1997} {ital The American Astronomical Society}

  13. A spectroscopic survey for lambda Bootis stars. II. The observational data

    NASA Astrophysics Data System (ADS)

    Paunzen, E.; Duffee, B.; Heiter, U.; Kuschnig, R.; Weiss, W. W.

    2001-07-01

    lambda Bootis stars comprise only a small number of all A-type stars and are characterized as nonmagnetic, Population i, late B to early F-type dwarfs which show significant underabundances of metals whereas the light elements (C, N, O and S) are almost normal abundant compared to the Sun. In the second paper on a spectroscopic survey for lambda Bootis stars, we present the spectral classifications of all program stars observed. These stars were selected on the basis of their Strömgren uvbybeta colors as lambda Bootis candidates. In total, 708 objects in six open clusters, the Orion OB1 association and the Galactic field were classified. In addition, 9 serendipity non-candidates in the vicinity of our program stars as well as 15 Guide Star Catalogue stars were observed resulting in a total of 732 classified stars. The 15 objects from the Guide Star Catalogue are part of a program for the classification of apparent variable stars from the Fine Guidance Sensors of the Hubble Space Telescope. A grid of 105 MK standard as well as ``pathological'' stars guarantees a precise classification. A comparison of our spectral classification with the extensive work of Abt & Morrell (\\cite{Abt95}) shows no significant differences. The derived types are 0.23 +/- 0.09 (rms error per measurement) subclasses later and 0.30 +/- 0.08 luminosity classes more luminous than those of Abt & Morrell (\\cite{Abt95}) based on a sample of 160 objects in common. The estimated errors of the means are +/- 0.1 subclasses. The characteristics of our sample are discussed in respect to the distribution on the sky, apparent visual magnitudes and Strömgren uvbybeta colors. Based on observations from the Observatoire de Haute-Provence, Osservatorio Astronomico di Padova-Asiago, Observatório do Pico dos Dias-LNA/CNPq/MCT, Chews Ridge Observatory (MIRA) and University of Toronto Southern Observatory (Las Campanas).

  14. VizieR Online Data Catalog: uvbyβ photometry of lambda Bootis stars (Paunzen+, 2001)

    NASA Astrophysics Data System (ADS)

    Paunzen, E.; Duffee, B.; Heiter, U.; Kuschnig, R.; Weiss, W. W.

    2001-06-01

    Lambda Bootis stars comprise only a small number of all A-type stars and are characterized as nonmagnetic, Population I, late B to early F-type dwarfs which show significant underabundances of metals whereas the light elements (C, N, O and S) are almost normal abundant compared to the Sun. In the second paper on a spectroscopic survey for lambda Bootis stars, we present the spectral classifications of all program stars observed. These stars were selected on the basis of their Stromgren uvbybeta colors as lambda Bootis candidates. In total, 708 objects in six open clusters, the Orion OB1 association and the Galactic field were classified. In addition, nine serendipity non-candidates in the vicinity of our program stars as well as 15 Guide Star Catalogue stars were observed resulting in a total of 732 classified stars. The 15 objects from the Guide Star Catalogue are part of a program for the classification of apparent variable stars from the Fine Guidance Sensors of the Hubble Space Telescope. A grid of 105 MK standard as well as ``pathological'' stars guarantees a precise classification. A comparison of our spectral classification with the extensive work of Abt & Morrell (1995, Cat. ) shows no significant differences. The derived types are 0.23+/-0.09 (rms error per measurement) subclasses later and 0.30+/-0.08 luminosity classes more luminous than those of Abt & Morrell (1995, Cat. )) based on a sample of 160 objects in common. The estimated errors of the means are +/-0.1 subclasses. The characteristics of our sample are discussed in respect to the distribution on the sky, apparent visual magnitudes and Stromgren uvbybeta colors. Table 2 lists all observed Galactic field stars. (1 data file).

  15. INTEGRATED POLARIZATION OF SOURCES AT {lambda} {approx} 1 m AND NEW ROTATION MEASURE AMBIGUITIES

    SciTech Connect

    Farnsworth, Damon; Rudnick, Lawrence; Brown, Shea

    2011-06-15

    We present an analysis of the polarization of compact radio sources from six pointings of the Westerbork Synthesis Radio Telescope at 350 MHz with 35% coverage in {lambda}{sup 2}. After correcting for the off-axis instrumental polarization with a simple analytical model, only a small number of 585 strong sources have significant polarizations at these wavelengths. The median depolarization ratio from 1.4 GHz for the strongest sources is <0.2, reinforcing the likelihood that radio galaxies are found in magnetized environments, even outside of rich clusters. Seven sources with significant 350 MHz polarization were selected for a more in-depth Faraday structure analysis. We fit the observed values Q/I and U/I as a function of {lambda}{sup 2} using both a depolarizing screen and two-component models. We also performed rotation measure (RM) Synthesis/Clean and standard fitting of polarization angle versus {lambda}{sup 2}. We find that a single RM, as found using polarization angle fitting or simple screen models, commonly provides a poor fit when the solutions are translated back into Q, U space. Thus, although a single 'characteristic' RM may be found using these techniques, the Faraday structure of the source may not be adequately represented. We also demonstrate that RM Synthesis may yield an erroneous Faraday structure in the presence of multiple, interfering RM components, even when cleaning of the Faraday spectrum is performed. We briefly explore the conditions under which RMs and Faraday structure results can be reliable. Many measurements in the literature do not meet these criteria; we discuss how these influence the resulting scientific conclusions and offer a prescription for obtaining reliable RMs.

  16. First observation and measurement of the resonant structure of the lambda_b->lambda_c pi-pi+pi- decay mode

    SciTech Connect

    Azzurri, P.; Barria, P.; Ciocci, M.A.; Donati, S.; Vataga, E.

    2009-12-01

    The authors present the first observation of the {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} decay using data from an integrated luminosity of approximately 2.4 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. They also present the first observation of the resonant decays {Lambda}{sub b}{sup 0} {yields} {Sigma}{sub c}(2455){sup 0} {pi}{sup +}{pi}{sup -} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -}, {Lambda}{sub b}{sup 0} {yields} {Sigma}{sub c}(2455){sup ++}{pi}{sup -}{pi}{sup -} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -}, {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}(2595){sup +}{pi}{sup -} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} and {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}(2625){sup +}{pi}{sup -} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -}, and measure their relative branching ratios.

  17. A Measurement of the Recoil Polarization of Electroproduced {Lambda}(1116)

    SciTech Connect

    Simeon McAleer

    2002-01-01

    The CEBAF Large Acceptance Spectrometer at the Thomas Jefferson National Laboratory was used to study the reaction e + p {yields} e{prime} + K{sup +} + {Lambda}(1116) for events where {Lambda}(1116) subsequently decayed via the channel {Lambda}(1116) {yields} p + {pi}{sup -}. Data were taken at incident electron beam energies of 2.5, 4.0, and 4.2 GeV during the 1999 E1C run period. They hyperon production spectra span the Q{sup 2} range from 0.5 to 2.8 GeV{sup 2} and nearly the entire range in the center of mass angles. The proton angular distribution in the {Lambda}(1116) rest frame is used to deduce the recoil polarization of the hyperon, and the W and cos {theta}{sub cm}{sup K+} dependence of the recoil polarization will be presented. The data show sizeable negative polarizations for the {Lambda}(1116) as a function of both cos {theta}{sub cm}{sup K+} and W.

  18. Spin-orbit splitting of {sub {lambda}}{sup 9}Be excited states studied with the SU{sub 6} quark-model baryon-baryon interactions

    SciTech Connect

    Fujiwara, Y.; Kohno, M.; Miyagawa, K.; Suzuki, Y.

    2004-10-01

    The previous Faddeev calculation of the two-alpha plus {lambda} system for {sub {lambda}}{sup 9}Be is extended to incorporate the spin-orbit components of the SU{sub 6} quark-model (QM) baryon-baryon interactions. We employ the Born kernel of the QM {lambda}N LS interaction and generate the spin-orbit component of the {lambda}{alpha} potential by {alpha}-cluster folding. The Faddeev calculation in the jj-coupling scheme implies that the direct use of the QM Born kernel for the {lambda}N LS component is not good enough to reproduce the small experimental value {delta}E{sub ls}{sup expt}=43{+-}5 keV for the 5/2{sup +}-3/2{sup +} splitting. This procedure predicts 3-5 times larger values in the models FSS and fss2. The spin-orbit contribution from the effective meson-exchange potentials in fss2 is argued to be unfavorable to the small ls splitting, through the analysis of the Scheerbaum factors for the single-particle spin-orbit potentials calculated in the G-matrix formalism.

  19. Short range correlations in the weak decay of {Lambda} hypernuclei

    SciTech Connect

    Parreno, A.; Ramos, A.; Oset, E.

    1995-05-01

    The differences found in the relativistic and nonrelativistic methods used in the literature to account for short range nuclear correlations in the decay of {Lambda} hypernuclei are analyzed. By means of a schematic microscopic model for the origin of correlations, the appropriate method to include them in nuclear processes is derived and is found to be the same one used in the nonrelativistic approach. The differences do not stem from relativistic effects but from the improper implementation of the correlations in the relativistic approach, which leads to several pathologies as shown in the paper. General formulas are given to evaluate the nonmesonic decay width of finite hypernuclei and results are obtained for {sub {Lambda}}{sup 5}He and {sub {Lambda}}{sup 12}C.

  20. Determination of the Lambda parameter from full lattice QCD

    SciTech Connect

    Goeckeler, M.; Horsley, R.; Irving, A.C.; Rakow, P.E.L.; Pleiter, D.; Schierholz, G.; Stueben, H.

    2006-01-01

    We present a determination of the QCD parameter {lambda} in the quenched approximation (n{sub f}=0) and for two flavors (n{sub f}=2) of light dynamical quarks. The calculations are performed on the lattice using O(a) improved Wilson fermions and include taking the continuum limit. We find {lambda}{sub n{sub f}=0}{sup MS}=259(1)(19) MeV and {lambda}{sub n{sub f}=2}{sup MS}=261(17)(26) MeV, using r{sub 0}=0.467 fm to set the scale. Extrapolating our results to five flavors, we obtain for the running coupling constant at the mass of the Z boson {alpha}{sub s}{sup MS}(m{sub Z})=0.112(1)(2)

  1. Prediction of narrow N* and {Lambda}* with hidden charm

    SciTech Connect

    Wu Jiajun; Molina, R.; Oset, E.; Zou, B. S.

    2011-10-24

    The interaction between various charmed mesons and charmed baryons, such as D-bar{Sigma}{sub c}-D-bar{Lambda}{sub c}, D-bar*{Sigma}{sub c}-D-bar*{Lambda}{sub c}, and related strangeness channels, are studied within the framework of the coupled channel unitary approach with the local hidden gauge formalism. Six narrow N* and {Lambda}* resonances are dynamically generated with mass above 4 GeV and width smaller than 100 MeV. These predicted new resonances definitely cannot be accommodated by quark models with three constituent quarks. We make estimates of production cross sections of these predicted resonances in p-barp collisions for PANDA at the forthcoming FAIR facility.

  2. Persistence behaviour of thiamethoxam and lambda cyhalothrin in transplanted paddy.

    PubMed

    Barik, Suhrid Ranjan; Ganguly, Pritam; Kunda, Samir Kumar; Kole, Ramen Kumar; Bhattacharyya, Anjan

    2010-10-01

    A field study was conducted in Pre-Kharif season 2007 on paddy to determine the persistence of thiamethoxam (12.6%) and lambda cyhalothrin (9.4%) [in a 'Readymix' formulation Alika 247 ZC], following the application of 33 g. a.i. ha⁻¹ (T₁) and 66 g. a.i. ha⁻¹ (T₂). Spraying of insecticide was done during milking stage of the crop (63 days after transplantation). Thiamethoxam and lambda cyhalothrin residues were estimated by HPLC and GLC respectively. The half-life values were 5.2-5.8 and 4.8 days for thiamethoxam and lambda cyhalothrin respectively. No residue was detected in the harvested paddy, straw, grain, and soil samples. PMID:20703448

  3. LOCAL MEASUREMENT OF {Lambda} USING PULSAR TIMING ARRAYS

    SciTech Connect

    Espriu, Domenec; Puigdomenech, Daniel

    2013-02-20

    We consider the propagation of gravitational waves (GWs) in de Sitter spacetime and how a non-zero value of the cosmological constant might affect their detection in pulsar timing arrays (PTAs). If {Lambda} {ne} 0, the waves are anharmonic in Friedmann-Robertson-Walker coordinates, and although this effect is very small it gives rise to noticeable consequences for GWs originating in extragalactic sources such as spiraling black hole binaries. The results indicate that the timing residuals induced by GWs from such sources in PTAs will show a peculiar angular dependence with a marked enhancement around a particular value of the angle subtended by the source and the pulsars, depending mainly on the actual value of the cosmological constant and the distance to the source. The position of the peak could represent a gauge of the value of {Lambda}. The enhancement that the new effect brings about could facilitate the first direct detection of GWs while representing a local measurement of {Lambda}.

  4. Spectroscopic Research of Lambda Hypdernuclei at JLab Hall C

    SciTech Connect

    Gogami, Toshiyuki; et. al.,

    2014-03-01

    A Lambda hyperon which has a strangeness can be bound in deep inside of a nucleus since a Λ does not suffer from the Pauli exclusion principle from nucleons. Thus, a Λ could be a useful tool to investigate inside of a nucleus. Since 2000, Lambda hypernuclear spectroscopic experiments by the (e,e'k) reaction have been performed at the experimental hall C in Thomas Jefferson National Accelerator Facility (JLab Hall C). An experiment, JLab E05-115 was carried out to investigate Lambda hypernuclei with a wide mass range (the mass number, A = 7, 9, 10, 12, 52). The latest analysis status of JLab E05-115 experiment is discussed in the present article.

  5. Characterization of a lymphoblastoid line deleted for lambda immunoglobulin genes

    SciTech Connect

    Hough, C.A., White, B.N., Holden, J.A.

    1995-04-01

    While characterizing the cat eye syndrome (CES) supernumerary chromosome for the presence of {lambda} immunoglobulin gene region sequences, a lymphoblastoid cell line from one CES patient was identified in which there was selection of cells deleted from some IGLC and IGLV genes. Two distinct deletions, one on each chromosome 22, were identified, presumably arising from independent somatic recombination events occurring during B-lymphocyte differentiation. The extent of the deleted regions was determined using probes from the various IGLV subgroups and they each covered at least 82 kilobases. The precise definition of the deletions was not possible because of conservation of some restriction sites in the IGLV region. The cell line was used to map putative IGLV genes within the recombinant phage {lambda}V{lambda}135 to the distal part of the IGLV gene region. 35 refs., 4 figs.

  6. He II lambda 1640/lambda 4686 and Ly-alpha/H-beta ratios in the extraordinary Seyfert galaxy Markarian 359

    NASA Technical Reports Server (NTRS)

    Macalpine, G. M.; Davidson, K.; Gull, T. R.; Wu, C.-C.

    1985-01-01

    The exceptionally narrow-lined Seyfert 1 galaxy Mrk 359 is ideally suited for determining reddening via the He II lambda 1640/lambda 4686 emission-line ratio. Here the validity of He II lines as a reddening indicator for quasars and Seyfert galaxies is reexamined and confirmed in the context of the most complete photoionization models available. In addition, lambda 1640 equivalent width measurements are shown to support previous contentions of substantial differences between observed and intrinsic quasar far-ultraviolet continua. Then IUE satellite and ground-based spectral data are presented, with the surprising result that both the lambda 1640/lambda 4686 and Ly-alpha/H-beta ratios do not differ greatly from case B recombination values in Mrk 359. This object is only slightly reddened, and it shows no evidence for extended, high-optical-depth H(+)/H(0) transition regions in the line-emitting gas. The very narrow lines and lack of deep transition regions and/or reddening may be related. In addition, Mrk 359 has low luminosity compared with most other Seyfert 1 galaxies, measured emission lines suggest an unusually high ionization parameter, and there is a hint of low nitrogen abundance. Further work is needed to examine possible relationships among all these peculiar properties.

  7. Measurement of Lambda and Lambda(macro) particles in Au+Au collisions at the square root of S(NN) = 130 GeV.

    PubMed

    Adcox, K; Adler, S S; Ajitanand, N N; Akiba, Y; Alexander, J; Aphecetche, L; Arai, Y; Aronson, S H; Averbeck, R; Awes, T C; Barish, K N; Barnes, P D; Barrette, J; Bassalleck, B; Bathe, S; Baublis, V; Bazilevsky, A; Belikov, S; Bellaiche, F G; Belyaev, S T; Bennett, M J; Berdnikov, Y; Botelho, S; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J; Butsyk, S; Carey, T A; Chand, P; Chang, J; Chang, W C; Chavez, L L; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choudhury, R K; Christ, T; Chujo, T; Chung, M S; Chung, P; Cianciolo, V; Cole, B A; D'Enterria, D G; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dinesh, B V; Drees, A; Durum, A; Dutta, D; Ebisu, K; Efremenko, Y V; el-Chenawi, K; En'yo, H; Esumi, S; Ewell, L; Ferdousi, T; Fields, D E; Fokin, S L; Fraenkel, Z; Franz, A; Frawley, A D; Fung, S-Y; Garpman, S; Ghosh, T K; Glenn, A; Godoi, A L; Goto, Y; Greene, S V; Grosse Perdekamp, M; Gupta, S K; Guryn, W; Gustafsson, H-A; Haggerty, J S; Hamagaki, H; Hansen, A G; Hara, H; Hartouni, E P; Hayano, R; Hayashi, N; He, X; Hemmick, T K; Heuser, J M; Hibino, M; Hill, J C; Ho, D S; Homma, K; Hong, B; Hoover, A; Ichihara, T; Imai, K; Ippolitov, M S; Ishihara, M; Jacak, B V; Jang, W Y; Jia, J; Johnson, B M; Johnson, S C; Joo, K S; Kametani, S; Kang, J H; Kann, M; Kapoor, S S; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D J; Kim, H J; Kim, S Y; Kim, Y G; Kinnison, W W; Kistenev, E; Kiyomichi, A; Klein-Boesing, C; Klinksiek, S; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kotchetkov, D; Kozlov, A; Kroon, P J; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Lauret, J; Lebedev, A; Lee, D M; Leitch, M J; Li, X H; Li, Z; Lim, D J; Liu, M X; Liu, X; Liu, Z; Maguire, C F; Mahon, J; Makdisi, Y I; Manko, V I; Mao, Y; Mark, S K; Markacs, S; Martinez, G; Marx, M D; Masaike, A; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E; Merschmeyer, M; Messer, F; Messer, M; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mühlbacher, F; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagasaka, Y; Nagle, J L; Nakada, Y; Nandi, B K; Newby, J; Nikkinen, L; Nilsson, P; Nishimura, S; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Ono, M; Onuchin, V; Oskarsson, A; Osterman, L; Otterlund, I; Oyama, K; Paffrath, L; Pal, D; Palounek, A P T; Pantuev, V S; Papavassiliou, V; Pate, S F; Peitzmann, T; Petridis, A N; Pinkenburg, C; Pisani, R P; Pitukhin, P; Plasil, F; Pollack, M; Pope, K; Purschke, M L; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Rosati, M; Rose, A A; Ryu, S S; Saito, N; Sakaguchi, A; Sakaguchi, T; Sako, H; Sakuma, T; Samsonov, V; Sangster, T C; Santo, R; Sato, H D; Sato, S; Sawada, S; Schlei, B R; Schutz, Y; Semenov, V; Seto, R; Shea, T K; Shein, I; Shibata, T-A; Shigaki, K; Shiina, T; Shin, Y H; Sibiriak, I G; Silvermyr, D; Sim, K S; Simon-Gillo, J; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sorensen, S; Stankus, P W; Starinsky, N; Steinberg, P; Stenlund, E; Ster, A; Stoll, S P; Sugioka, M; Sugitate, T; Sullivan, J P; Sumi, Y; Sun, Z; Suzuki, M; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Taniguchi, E; Tannenbaum, M J; Thomas, J; Thomas, J H; Thomas, T L; Tian, W; Tojo, J; Torii, H; Towell, R S; Tserruya, I; Tsuruoka, H; Tsvetkov, A A; Tuli, S K; Tydesjö, H; Tyurin, N; Ushiroda, T; Van Hecke, H W; Velissaris, C; Velkovska, J; Velkovsky, M; Vinogradov, A A; Volkov, M A; Vorobyov, A; Vznuzdaev, E; Wang, H; Watanabe, Y; White, S N; Witzig, C; Wohn, F K; Woody, C L; Xie, W; Yagi, K; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, Z; Zhou, S; Zhou, S

    2002-08-26

    We present results on the measurement of Lambda and Lambda(macro) production in Au+Au collisions at square root of (S (NN) = 130 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider. The transverse momentum spectra were measured for minimum bias and for the 5% most central events. The Lambda;/Lambda ratios are constant as a function of p(T) and the number of participants. The measured net Lambda density is significantly larger than predicted by models based on hadronic strings (e.g., HIJING) but in approximate agreement with models which include the gluon-junction mechanism. PMID:12190391

  8. Observation of parity violation in the Omega- ---> Lambda K- decay

    SciTech Connect

    Lu, L.C.; Burnstein, R.A.; Chakravorty, A.; Chen, Y.C.; Choong, W.-S.; Clark, K.; Dukes, E.C.; Durandet, C.; Felix, J.; Fu, Y.; Gidal, G.; Gustafson, H.R.; Holmstrom, T.; Huang, M.; James, C.; Jenkins, C.M.; Jones, T.D.; Kaplan, D.M.; Longo, M.J.; Luebke, W.; Luk, K.-B.; /Taiwan, Inst. Phys. /UC, Berkeley /Fermilab /Guanajuato U. /IIT, Chicago /Lausanne U. /LBL, Berkeley /Michigan U. /South Alabama U. /Virginia U.

    2005-05-01

    The {alpha} decay parameter in the process {Omega}{sup -} {yields} {Lambda}K{sup -} has been measured from a sample of 4.50 million unpolarized {Omega}{sup -} decays recorded by the HyperCP (E871) experiment at Fermilab and found to be [1.78 {+-} 0.19(stat) {+-} 0.16(syst)] x 10{sup -2}. This is the first unambiguous evidence for a nonzero {alpha} decay parameter, and hence parity violation, in the {Omega}{sup -} {Lambda}K{sup -} decay.

  9. Technical challenges involved in supporting the Lambda Point Experiment

    NASA Technical Reports Server (NTRS)

    Petrac, D.; Israelsson, U.; Otth, D.; Simmons, L.; Staats, J.; Thompson, A.

    1990-01-01

    The Lambda Point Experiment (LPE) is one of the instruments included in the U.S. Microgravity Payload Mission 1 planned for one of the Space Shuttle flights in 1992. The objective of the experiment is to measure the heat capacity of liquid helium within a narrow interval around the transition between superfluid and normal helium (the lambda point) with an unprecedented temperature resolution of about 10 to the -10th. Multiple technical challenges are presented in the areas of structural support, safety analysis, and modal frequency tests. This paper describes the technical challenges of JPL's multidisciplinary involvement in support of these experiments in microgravity.

  10. Accurate LTE abundances for some lambda Boo stars

    NASA Astrophysics Data System (ADS)

    Andrievsky, S. M.; Chernyshova, I. V.; Klochkova, V. G.; Panchuk, V. E.

    1998-04-01

    High-resolution and high S/N CCD spectra were analyzed to determine accurate LTE abundances in four lambda Boo stars: pi1 Ori, 29 Cyg, HR 8203 and 15 And. In general, 14 chemical elements were investigated. The main results are the following: all stars have a strong deficiency of the majority of investigated metals. Oxygen exhibits a moderate deficiency. The carbon abundance is close to the solar one. The results obtained support an accretion/diffusion model, which is currently adopted for the explanation of the lambda Boo phenomenon.