搜索结果: 1-15 共查到“天文学 Activity”相关记录55条 . 查询时间(0.043 秒)
Scientists last autumn revealed that the gas phosphine was found in trace amounts in Venus’ upper atmosphere. That discovery promised the slim possibility that phosphine serves as a biological signatu...
Ionospheric disturbances generated by different natural processes and by human activity in Earth plasma environment
ionosphere Earth plasma environment
2015/9/14
The magnetosphere-ionosphere-thermosphere subsystem is strongly coupled via the electric field, particle precipitation, heat flows and small scale interaction. Satellites in situ measurements and grou...
Chandra Observations of the Bursting X-Ray Transient SAX J1747.0–2853 during Low-Level Accretion Activity
SAX J1747.0–2853 stars
2014/12/26
We present Chandra/ACIS observations of the bursting X-ray transient SAX J1747.0-2853 performed on 2001 July 18. We detected a bright source at the position of R.A. = 17h47m02.s60 and decl. = -28°52'5...
The first IRAM/PdBI polarimetric millimeter survey of active galactic nuclei. II. Activity and properties of individual sources
IRAM/PdBI polarimetric millimeter survey properties individual sources
2012/2/21
We present an analysis of the linear polarization of six active galactic nuclei - 0415+379 (3C~111), 0507+179, 0528+134 (OG+134), 0954+658, 1418+546 (OQ+530), and 1637+574 (OS+562). Our targets were m...
Insights on the Formation, Evolution, and Activity of Massive Galaxies From Ultra-Compact and Disky Galaxies at z=2-3
Insights Formation Evolution Activity Massive Galaxies Disky Galaxies
2011/10/9
We present our results on the structure and activity of massive galaxies at z=1-3 using one of the largest (166 with M_star>=5e10 M_sun) and most diverse samples of massive galaxies derived from the G...
The complete census of optically selected AGNs in the Coma Supercluster: the dependence of AGN activity on the local environment
Galaxies: clusters: individual: Coma Galaxies evolution Galaxies nuclei
2011/10/11
To investigate the dependence of the occurrence of active galactic nuclei (AGNs) on local galaxy density, we study the nuclear properties of ~5000 galaxies in the Coma Supercluster whose density spans...
The long-term millimeter activity of active galactic nuclei
Galaxies: active — Quasars: general — Radiation mechanisms: non-thermal
2011/10/18
We analyze the long-term evolution of the fluxes of six active galactic nuclei (AGN) - 0923+392, 3C 111, 3C 273, 3C 345, 3C 454.3, and 3C 84 - in the frequency range 80-267 GHz using archival calibrat...
The HARPS search for southern extra-solar planets. XXXI. Magnetic activity cycles in solar-type stars: statistics and impact on precise radial velocities
Planetary systems – Stars: activity – Stars: chromospheres – Line: profi les – Techniques: radial velocities – Techniques:spectroscopic
2011/10/17
Context. Searching for extrasolar planets through radial velocity measurements relies on the stability of stellar photospheres. Aims. We aim at characterizing the statistical properties of magnetic ac...
Deriving the radial-velocity variations induced by stellar activity from high-precision photometry - Test on HD189733 with simultaneous MOST/SOPHIE data
late-type – stars: activity – stars: rotation – techniques: radial velocity – planetary systems – stars: individual
2011/10/19
Stellar activity induces apparent radial velocity (RV) variations in late-type main-sequence stars that may hamper the detection of low-mass planets and the measurement of their mass. We use simultane...
Quasi periodic oscillations of solar active regions in connection with their flare activity - NoRH observations
Oscillations, Solar Radio Emission Radio Bursts, Association with Flares
2011/9/29
The sunspot-associated sources at the frequency of 17 GHz give information on plasma parameters in the regions of magnetic field about B=2000 G at the level of the chromosphere-corona transition regio...
The HARPS search for southern extra-solar planets. XXX. Planetary systems around stars with solar-like magnetic cycles and short-term activity variation
stars: planetary systems – techniques: radial velocities – stars: activity – stars: individual: HD7199 – stars: individual
2011/9/30
We present the discovery of four new long-period planets within the HARPS high-precision sample: \object{HD137388}b ($M\sin{i}$ = 0.22 $M_J$), \object{HD204941}b ($M\sin{i}$ = 0.27 $M_J$), \object{HD7...
The long-lasting activity of 3C 454.3. GASP-WEBT and satellite observations in 2008-2010
galaxies: active – galaxies: quasars: general – galaxies: quasars: individual: 3C 454.3 – galaxies: jets
2011/9/28
We present multiwavelength observations of 3C 454.3 from April 2008 to March 2010. The radio to optical data are mostly from the GASP-WEBT, UV and X-ray data from Swift, and gamma-ray data from the AG...
High spatial resolution monitoring of the activity of BA supergiant winds
High spatial resolution the activity BA supergiant winds
2011/1/13
There are currently two optical interferometry recombiners that can provide spectral resolutions better than 10000, AMBER/VLTI operating in the H-K bands, and VEGA/CHARA, recently commissioned, opera...
Variation in the frequency separations with activity and impact on stellar parameter determination
Variation frequency separations activity impact
2010/11/15
Frequency separations used to infer global properties of stars through asteroseismology can change depending on the strength and at what epoch of the stellar cycle the p-mode frequencies are measured....
Variable circumstellar activity of V351 Orionis
stars:pre main sequence (stars) circumstellar matter stars:individual
2010/11/16
Context. Emission and absorption line profiles which are formed in the interaction of pre-main sequence (PMS) stars and their circumstellar environment are found to be variable at various timescales.