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Photometric I band light curves of 21 ultra cool M and L dwarfs are presented. Variability with amplitudes of 0.01 to 0.055 magnitudes (RMS) with typical timescales of an hour to several hours are discovered in half of these objects.…

天体物理学 · 物理学 2007-05-23 C. A. L. Bailer-Jones

The evolution of the physical parameters of magnetic bright points (MBPs) located in the quiet Sun (mainly in the interwork) during their lifetime is studied. First we concentrate on the detailed description of the magnetic field evolution…

太阳与恒星天体物理 · 物理学 2016-08-10 D. Utz , J. C. del Toro Iniesta , L. R. Bellot Rubio , J. Jurčák , V. Martínez Pillet , S. K. Solanki , W. Schmidt

Measurements of maximum magnetic flux, minimum intensity, and size are presented for 12 967 sunspot umbrae detected on the NASA/NSO spectromagnetograms between 1993 and 2004 to study umbral structure and strength during the solar cycle. The…

太阳与恒星天体物理 · 物理学 2011-04-07 T. A. Schad , M. J. Penn

We use N-body simulations to study the evolution of cuspy cold dark matter (CDM) halos in the gravitational potential of a massive host. Tidal mass losses reshape CDM halos, leaving behind bound remnants whose characteristic densities are…

星系天体物理 · 物理学 2021-06-03 Raphaël Errani , Julio F. Navarro

Recently, complex horizontal patterns of umbral oscillations have been reported, but their physical nature and origin are still not fully understood. Here we show that the two-dimensional patterns of umbral oscillations of slow waves are…

太阳与恒星天体物理 · 物理学 2024-06-05 Juhyung Kang , Jongchul Chae , Kyuhyoun Cho , Soosang Kang , Eun-Kyung Lim

High resolution spectropolarimetric observations of 3 sunspots taken with Hinode demonstrate the existence of supersonic downflows at or close to the umbra-penumbra boundary which have not been reported before. These downflows are confined…

太阳与恒星天体物理 · 物理学 2015-05-20 Rohan E. Louis , Luis R. Bellot Rubio , Shibu K. Mathew , P. Venkatakrishnan

We present fast cadence and high resolution observations of flare ribbons from the Solar Orbiter Extreme Ultraviolet Imager (EUI). Utilizing the short-exposure observations from the EUI High Resolution Imager in EUV (HRIEUV), we find…

Several deep observations such as those carried out at the Canada-France-Hawaii Telescope (CFHT) have revealed prominent Low Surface Brightness (LSB) fine structures that change the apparent morphology of galaxies. Previous photometry…

星系天体物理 · 物理学 2019-12-18 B. Mancillas , P. -A. Duc , F. Combes , F. Bournaud , E. Emsellem , M. Martig , L. Michel-Dansac

We present results from our Very Large Telescope large program to study the dynamical evolution of local Ultraluminous Infrared Galaxies (ULIRGs) and QSOs. This paper is the second in a series presenting the stellar kinematics of 54 ULIRGs,…

The sunspot penumbra is a transition zone between the strong vertical magnetic field area (sunspot umbra) and the quiet Sun. The penumbra has a fine filamentary structure that is characterized by magnetic field lines inclined toward the…

太阳与恒星天体物理 · 物理学 2010-12-02 I. N. Kitiashvili , A. G. Kosovichev , N. N. Mansour , A. A. Wray

A numerical evidence for the universality of the bound-zone peculiar velocity profile in a LambdaCDM universe is presented. Analyzing the dark matter halo catalogs from the Millennium-II simulation, we determine the average peculiar…

宇宙学与河外天体物理 · 物理学 2016-12-15 Jounghun Lee

We analyzed the size, intensity, and magnetic field strength of sunspot umbrae to compare the present cycle 24 with the previous one. We used data of the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory and selected…

太阳与恒星天体物理 · 物理学 2015-06-18 Christoph Kiess , Reza Rezaei , Wolfgang Schmidt

We present an analysis of twisting motions in penumbral filaments in sunspots located at heliocentric angles from $30^\circ$ to $48^\circ$ using three time series of blue continuum images obtained by the Broadband Filter Imager (BFI)…

太阳与恒星天体物理 · 物理学 2015-05-19 Lokesh Bharti , Sami K. Solanki , Johann Hirzberger

We construct and analyze a u-band selected galaxy sample from the SDSS Southern Survey, which covers 275 sq. deg. The sample includes 43223 galaxies with spectroscopic redshifts in the range 0.005<z<0.3 and with 14.5<u<20.5. The S/N in the…

Star-forming regions that are visible at 3.6 microns and Halpha but not in the u,g,r,i,z bands of the Sloan Digital Sky survey (SDSS), are measured in five nearby spiral galaxies to find extinctions averaging ~3.8 mag and stellar masses…

We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited scans of the Fe I 617.3…

太阳与恒星天体物理 · 物理学 2015-06-23 S. Esteban Pozuelo , L. R. Bellot Rubio , J. de la Cruz Rodriguez

As the 7 December 2007 equinox of Uranus approached, ring and atmosphere observers produced a substantial collection of observations using the 10-m Keck telescope and the Hubble Space Telescope. Those spanning the period from 7 June 2007…

地球与行星天体物理 · 物理学 2015-03-09 Lawrence Sromovsky , Patrick Fry , Heidi Hammel , William Ahue , Imke de Pater , Kathy Rages , Mark Showalter , Marcos van Dam

The discovery of Ultra-Faint Dwarf (UFD) galaxies in the halo of the Milky Way extends the faint end of the galaxy luminosity function to a few hundred solar luminosities. This extremely low luminosity regime poses a significant challenge…

星系天体物理 · 物理学 2015-05-30 R. R. Munoz , N. Padmanabhan , M. Geha

We use the very deep and homogeneous I-band selected dataset of the FORS Deep Field (FDF) to trace the evolution of the luminosity function over the redshift range 0.5 < z < 5.0. We show that the FDF I-band selection down to I(AB)=26.8…

Relying on the assumption that the interchange convection of magnetic flux tubes is the physical cause for the existence of sunspot penumbrae, we propose a model in which the dynamical evolution of a thin magnetic flux tube reproduces the…

天体物理学 · 物理学 2016-08-30 R. Schlichenmaier , K. Jahn , H. U. Schmidt