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5 results on '"Fu, J.-N."'

1. Constraining the Evolution of ZZ Ceti

Author

Mukadam A. S., Kepler S. O., Winget D. E., Nather R. E., Kilic M., Mullally F., Hippel T. von, Kleinman S. J., Nitta A., Guzik J. A., Bradley P. A., Matthews J., Sekiguchi K., Sullivan D. J., Shobbrook R. R., Birch P., Jiang X. J., Xu D. W., Joshi S., Ashoka B.N., Ibbetson P., Leibowitz E., Ofek E. O., Meištas E. G., Janulis R., Ališauskas D., Kalytis R., Handler G., Kilkenny D., O’Donoghue D., Kurtz D. W., Müller M., Moskalik P., Ogłoza W., Zoła S., Krzesiński J., Johannessen F., Gonzalez-Perez J. M., Solheim J-E., Silvotti R., Bernabei S., Vauclair G., Dolez N., Fu J. N., Chevreton M., Manteiga M., Súarez O., Ulla A., Cunha M. S., Metcalfe T. S., Kanaan A., Fraga L., Costa A. F. M., Giovannini O., Fontaine G., Bergeron P., O’Brien M. S., Sanwal D., Wood M. A., Ahrens T. J., Silvestri N., Klumpe E. W., Kawaler S. D., Riddle R., Reed M. D., and Watson T. K.

Subjects
stars, white dwarfs, individual, ZZ Cet, R548 - stars, pulsations, evolution, Astronomy, QB1-991
Abstract

We report our analysis of the stability of pulsation periods in the DAV star (pulsating hydrogen atmosphere white dwarf) ZZ Ceti, also called R548. Based on observations that span 31 years, we conclude that the period 213.132605 s observed in ZZ Ceti drifts at a rate dP/dt≤(5.5±1.9)×10−15 s/s, after correcting for proper motion. Our results are consistent with previous Ṗ values for this mode and an improvement over them due to the larger time-base. The characteristic stability timescale implied for the pulsation period is |P/ Ṗ|≥1.2 Gyr, comparable to the theoretical cooling timescale for the star. Our current stability limit for the period 213.132605 s is only slightly less than the present measurement for G117-B15A for the period 215.2 s, another DAV, establishing this mode in ZZ Ceti as the second most stable optical clock known, more stable than atomic clocks and most pulsars.

Published
2003
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2. Precise determination of stellar parameters of the ZZ Ceti and DAZ white dwarf GD 133 through asteroseismology.

Author

Fu, J-N, Vauclair, G, Su, J, Fox Machado, L, Colas, F, Kim, S-L, Cang, T Q, Li, C, Niu, H B, Xue, H F, Li, Y, Jiang, X-J, Michel, R, Alvarez, M, Dolez, N, Ma, L, Esamdin, A, and Liu, J Z

Subjects
*WHITE dwarf stars, *GRAVITATIONAL interactions, *HEAVY elements, *ATMOSPHERIC composition, *STELLAR oscillations, *PLANETESIMALS
Abstract

An increasing number of white dwarf stars shows atmospheric chemical composition polluted by heavy elements accreted from debris disc material. The existence of such debris discs strongly suggests the presence of one or more planet(s) whose gravitational interaction with rocky planetesimals is responsible for their disruption by tidal effect. The ZZ Ceti pulsator and polluted DAZ white dwarf GD 133 are good candidates for searching such a potential planet. We started in 2011 a photometric follow-up of its pulsations. As a result of this work in progress, we used the data gathered from 2011 to 2015 to make an asteroseismological analysis of GD 133, providing the star parameters from the best-fitting model with M / M ⊙ = 0.630 ± 0.002, T eff = 12 400 ± 70 K, log(M He/ M) = −2.00 ± 0.02, log(M H/ M) = −4.50 ± 0.02, and determining a rotation period of ≈7 d. [ABSTRACT FROM AUTHOR]

Published
2019
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3. The pulsations of PG 1351+489

Author

Redaelli, M., Kepler, S. O., Costa, José Eduardo, Winget, D. E., Handler, Gerald, Castanheira, B. G., Kanaan, A., Fraga, L., Henrique, P., Giovannini, O., Provençal, J. L., Shipman, H. L., Dalessio, J., Thompson, S. E., Mullally, Fergal, Brewer, M. M., Childers, D., Oksala, Mary E., Rosen, R., Wood, M. A., Reed, M. D., Walter, B., Strickland, W., Chandler, D., Watson, T. K., Nather, R. E., Montgomery, M. H., Bischoff-Kim, A., Hansen, Candice J., Nitta, A., Kleinman, S. J., Claver, C. F., Brown, Timothy M., Sullivan, D. J., Kim, S.-L., Chen, Wen-Ping, Yang, M., Shih, C.-Y., Zhang, X., Jiang, X., Fu, J.-N., Seetha, S., Ashoka, B. N., Marar, T. M. K., Baliyan, Kiran S., Vats, H. O., Chernyshev, A. V., Ibbetson, P., Leibowitz, E. M., Hemar, S., Sergeev, A. V., Andreev, M. V., Janulis, R., Meistas, E. G., Moskalik, P. A., Pajdosz, G., Baran, A., Winiarski, M., Zola, S., Ogloza, W., Siwak, M., Bognar, Zs., Solheim, J.-E., Sefako, R., Buckley, D., O'Donoghue, Darragh, Nagel, T., Silvotti, R., Bruni, I., Fremy, Jean-René, Vauclair, Gérard, Chevreton, Michel, Dolez, N., Pfeiffer, B., Barstow, Martin A., Creevey, Orlagh L., Kawaler, Steven D., Clemens, J. C., Instituto de Física, Universidade Federal do Rio Grande do Sul, Department of Astronomy and McDonald Observatory, University of Texas, Austin, Institut für Astronomie, Universität Wien (IfA), Departamento de Física, Universidade Federal de Santa Catarina, Southern Observatory for Astrophysical Research, Departamento de Física e Química, Universidade de Caxias do Sul, Department of Physics and Astronomy, University of Delaware, Delaware Asteroseismic Research Center, Mt Cuba Observatory, Greenville, SETI Institute, NASA Ames Research Center, Moffett Field, William Jewell College, Department of Math and Science, Delaware County Community College, Bartol Research Institute, University of Delaware, National Radio Astronomy Observatory, Green Bank (NRAO), Florida Institute of Technology, Department of Physics and Space Sciences, Melbourne, Baker Observatory, Missouri State University, Meyer Observatory and Central Texas Astronomical Society, Waco, Southwestern University, Department of Chemistry, Physics and Astronomy, Georgia College and State University, University of Colorado, Joint Institute for Laboratory Astrophysics (JILA), Gemini Observatory, Kitt Peak National Observatory, National Optical Astronomy Observatory, Tucson, Las Cumbres Observatory, Goleta, Victoria University of Wellington, Korea Astronomy and Space Science Institute (KASI), Lulin Observatory, National Astronomical Observatoires-CAS, Department of Astronomy, Beijing Normal University, Indian Space Research Organization, Physical Research Laboratory, Astronomy & Astrophysics Division, Astronomical Institute, Tel Aviv University (TAU), Main Astronomical Observatory, Academy of Sciences of Ukraine, Institute of Theoretical Physics and Astronomy, Vilnius University, Centrum Astronomiczne im. M. Kopernika, Warszawa (CAMK), Mount Suhora Observatory, Cracow Pedagogical University, Astronomical Observatory, Jagiellonia University, Konkoly Observatory, Research Center for Astronomy and Earth Sciences, University of Oslo (UiO), South African Astronomical Observatory (SAAO), Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, INAF-Osservatorio Astrofisico di Torino (INAF-OATo), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Etoile, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Ingénierie, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Astronomy Department, Leicester University, Instituto de Astrofísica de Canarias (IAC), Department of Physics and Astronomy, Iowa State University, and Department of Physics and Astronomy, University of North Carolina

Subjects
oscillations [stars], [SDU]Sciences of the Universe [physics], evolution [stars], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], individual: PG 1351+489 [stars], white dwarfs
Abstract

International audience; PG 1351+489 is one of the 20 DBVs - pulsating helium-atmosphere white dwarf stars - known and has the simplest power spectrum for this class of star, making it a good candidate to study cooling rates. We report accurate period determinations for the main peak at 489.334 48 s and two other normal modes using data from the Whole Earth Telescope (WET) observations of 1995 and 2009. In 2009, we detected a new pulsation mode and the main pulsation mode exhibited substantial change in its amplitude compared to all previous observations. We were able to estimate the star's rotation period, of 8.9 h, and discuss a possible determination of the rate of period change of (2.0 ± 0.9) × 10-13 s s -1, the first such estimate for a DBV.

Published
2011
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4. Asteroseismology of the ZZ Ceti star HS 0507+0434B★.

Author

Fu, J.-N., Dolez, N., Vauclair, G., Machado, L. Fox, Kim, S.-L., Li, C., Chen, L., Alvarez, M., Su, J., Charpinet, S., Chevreton, M., Michel, R., Yang, X. H., Li, Y., Zhang, Y. P., Molnar, L., and Plachy, E.

Subjects
*WHITE dwarf stars, *STELLAR oscillations, *CONSTRAINTS (Physics), *ASTRONOMICAL observations, *STELLAR luminosity function, *STELLAR rotation, *TIME series analysis
Abstract

The pulsating DA white dwarfs (ZZ Ceti stars) are g-mode non-radial pulsators. Asteroseismology provides strong constraints on their global parameters and internal structure. Since all the DA white dwarfs falling in the ZZ Ceti instability strip do pulsate, the internal structure derived from asteroseismology brings knowledge for the DA white dwarfs as a whole group. HS 0507+0434B is one of the ZZ Ceti stars which lies approximately in the middle of the instability strip for which we have undertaken a detailed asteroseismological study. We carried out multisite observation campaigns in 2007 and from 2009 December to 2010 January. In total, 206 h of photometric time series have been collected. They have been analysed by means of Fourier analysis and simultaneous multifrequency sine wave fitting. In total, 39 frequency values are resolved including six triplets and a number of linear combinations. We identify the triplets as ℓ = 1 g modes split by rotation. We derived the period spacing, the rotational splitting and the rotation rate. From the comparison of the observed periods with the theoretical periods of a series of models, we estimate the fundamental parameters of the star: its total mass M*/M⊙ = 0.675, its luminosity L/L⊙ = 3.5 × 10−3, and its hydrogen mass fraction MH/M* = 10−8.5. [ABSTRACT FROM AUTHOR]

Published
2013
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5. Preliminary identification of the observed pulsation modes of ZZ Ceti star KUV 03442+0719.

Author

Su, J., Li, Y., and Fu, J.-N.

Subjects
*STELLAR oscillations, *PHOTOMETRY, *TIME series analysis, *SCIENTIFIC observation, *ESTIMATION theory, *ROTATIONAL motion
Abstract

Highlights: [•] We obtained new photometric time series of the ZZ Ceti star KUV 03442+0719. [•] We found rotational splits of l =1 and l =2 modes in this star. [•] The detection of rotational splits helps us to estimate the mean rotation period. [•] By using the asymptotic analysis we get preliminary identification of all of the observed periods. [Copyright &y& Elsevier]

Published
2014
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