Precessing collimated outflows in the planetary nebula IC 4846     

Luis F. Miranda  Martín A. Guerrero  José M. Torrelles 《Monthly notices of the Royal Astronomical Society》2001,322(1):195-200

We present [N  ii ] and H α images and high-resolution long-slit spectra of the planetary nebula IC 4846, which reveal, for the first time, its complex structure and the existence of collimated outflows. The object consists of a moderately elongated shell, two (and probably three) pairs of collimated bipolar outflows at different orientations, and an attached circular shell. One of the collimated pairs is constituted by two curved, extended filaments the properties of which indicate a high-velocity, bipolar precessing jet. A difference of ≃10 km s⁻¹ is found between the systemic velocity of the precessing jets and the centroid velocity of the nebula, as recently reported for Hu 2-1. We propose that this difference is as a result of orbital motion of the ejection source in a binary central star. The orbital separation of 30 au and period 100 yr estimated for the binary are similar to those in Hu 2-1, linking the central stars of both planetary nebulae to interacting binaries. Extraordinary similarities also exist between IC 4846 and the bewildering planetary nebula NGC 6543, suggesting a similar formation history for both objects.  相似文献   

Can Jupiters be found by monitoring Galactic bulge microlensing events from northern sites?     

Yiannis Tsapras  Rachel A. Street  Keith Horne  Alan Penny  Fraser Clarke  Hans Deeg  Francisco Garzon  Simon Kemp  Maria Rosa Zapatero Osorio  Alejandro Oscoz Abad  Santiago Madruga Sanchez  Carlos Eiroa  Alcione Mora  Antxon Alberdi  rew Cameron  John K. Davies  Roger Ferlet  Carol Grady  Allan W. Harris  Javier Palacios  reas Quirrenbach  Heike Rauer  Jean Schneider  Dolf de Winter  Bruno Merin  Enrique Solano 《Monthly notices of the Royal Astronomical Society》2001,325(3):1205-1212

In 1998 the EXPORT team monitored microlensing event light curves using a charge-coupled device (CCD) camera on the IAC 0.8-m telescope on Tenerife to evaluate the prospect of using northern telescopes to find microlens anomalies that reveal planets orbiting the lens stars. The high airmass and more limited time available for observations of Galactic bulge sources make a northern site less favourable for microlensing planet searches. However, there are potentially a large number of northern 1-m class telescopes that could devote a few hours per night to monitor ongoing microlensing events. Our IAC observations indicate that accuracies sufficient to detect planets can be achieved despite the higher airmass.  相似文献   

行星和太阳内部的磁流体力学     

张可可  廖新浩 《天文研究与技术》2003,4(1):82-99

许多行星 (如木卫三 ,水星 ,地球 ,木星和土星 )和恒星 (如太阳 )具有内部磁场。对这些磁场的存在和变化的解释对行星科学家和天体物理学家是一个巨大的挑战。本文试图总结行星和恒星的导电流体内部磁流体力学研究的新近发展和困难。一般由热对流驱动的流动通过磁流体力学过程产生并维持在行星和恒星中的磁场。在行星中磁流体力学过程强烈地受到转动 ,磁场和球几何位型的综合影响。其动力学的关键方面涉及科里奥利力和洛伦兹力间的相互作用。在太阳中其流线 ,即处于对流层的薄的剪切流层在太阳的磁流体力学过程中扮演了一个基本的角色 ,并由之产生了 1 1年的太阳黑子周期。本文也给出了一个新的非线性三维太阳发电机模型。  相似文献   

Data analysis on the extrasolar planets using robust clustering     

Ing-Guey Jiang  Li-Chin Yeh  Wen-Liang Hung  Miin-Shen Yang 《Monthly notices of the Royal Astronomical Society》2006,370(3):1379-1392

We use both the conventional and more recently developed methods of cluster analysis to study the data of extrasolar planets (exoplanets). Using the data set with planetary mass M , orbital period P and orbital eccentricity e , we investigate the possible clustering in the  ln  M ,  ln  P ,  ln  P –ln  M ,   e   and ln   P – e spaces. There are two main implications: (1) mass distribution is continuous, and (2) orbital population could be classified into three clusters, which correspond to the exoplanets in the regimes of tidal, ongoing tidal and disc interaction, respectively.  相似文献   

The mean properties of planetary nebulae as a function of Peimbert class     

J. P. Phillips 《Monthly notices of the Royal Astronomical Society》2005,361(1):283-299

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Diffusive low optical depth particle discs truncated by planets     

Alice C. Quillen 《Monthly notices of the Royal Astronomical Society》2007,377(3):1287-1294

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Erratum: The Super WASP wide-field exoplanetary transit survey: candidates from fields 23 h < RA < 03 h     

《Monthly notices of the Royal Astronomical Society》2007,376(3):1424-1424

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A search for Ca ii emission enhancement in stars resulting from nearby giant planets     

S. H. Saar  M. Cuntz † 《Monthly notices of the Royal Astronomical Society》2001,325(1):55-59

We present a search for periodicities ( P _chr) in the chromospheric Ca  ii infrared triplet emission of several stars ( τ Boo, 51 Peg, υ And, ρ ¹ Cnc, ρ CrB, 70 Vir and GL 876) which may be directly attributable to interaction with close-in giant planets. Activity enhancements could arise from increased non-radiative heating and dynamo action in planet-induced tidal bulges (with P _chr≈ P _orb/2), or from interactions between the stellar and planetary magnetic fields (with P _chr≈ P _orb). We compare both P _chr and the phase dependence of the activity with the planetary orbital period P _orb, the orbital phase, and models. No significant P _chr or phase dependence attributable to planets can be clearly identified. We place approximate upper limits on the amplitude of any planet-induced activity. We identify a possible stellar rotation period for GL 876, and support previous period determinations for four other stars. We discuss the results and possible directions of future research.  相似文献   

The interaction of giant planets with a disc with MHD turbulence – III. Flow morphology and conditions for gap formation in local and global simulations     

John C. B. Papaloizou  Richard P. Nelson  Mark D. Snellgrove 《Monthly notices of the Royal Astronomical Society》2004,350(3):829-848

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Properties of planet-induced deviations in the astrometric microlensing centroid shift trajectory     

Cheongho Han  Chunguk Lee 《Monthly notices of the Royal Astronomical Society》2002,329(1):163-174

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