Related papers: Secular brightness curves of 272 comets
Here we present the results of visible range light curve observations of ten Centaurs using the Kepler Space Telescope in the framework of the K2 mission. Well defined periodic light curves are obtained in six cases allowing us to derive…
For seven decades, the widely held view has been that the formation, the migration and the decay of short-lived starspots explain the constantly changing light curves of chromospherically active stars. Our hypothesis is that these deceptive…
We study the time variations of the cycles of 20 active stars based on decades-long photometric or spectroscopic observations. A method of time-frequency analysis, as discussed in a companion paper, is applied to the data. Fifteen stars…
The young active star AB Dor (K1 IV-V) has been observed 16 times in the last three years with the XMM-Newton and Chandra observatories, totalling 650 ks of high-resolution X-ray spectra. The XMM/RGS observations with the highest and lowest…
We summarize the comet science provided by surveys. This includes surveys where the detections of comets are an advantageous benefit but were not part of the survey\'s original intent, as well as some pointed surveys where comet science was…
The cooling theory of neutron stars is corroborated by its comparison with observations of thermally emitting isolated neutron stars and accreting neutron stars in binary systems. An important ingredient for such an analysis is the age of…
I review the evolution of low-mass stars with outer convective zones over timescales of millions-to-billions of years, from the pre-main sequence to solar-age, ~4.6 Gyr (Bahcall et al. 1995; Amelin et al. 2010), and beyond. I discuss the…
An investigation on correlations between photospheric current helicity and subsur- face kinetic helicity is carried out by analyzing vector magnetograms and subsurface velocities for two rapidly developing active regions. The vector…
We present new analyses of the photometric lightcurve of Comet 1P/Halley during its 1985/86 apparition. As part of a world-wide campaign coordinated by the International Halley Watch (IHW), narrowband photometry was obtained with telescopes…
$Context.$ Pulsating stars are windows to the physics of stars enabling us to see glimpses of their interior. Not all stars pulsate, however. On the main sequence, pulsating stars form an almost continuous sequence in brightness, except for…
Meteor light curves are sometimes known to display flickering: rapid, quasi-periodic variations in brightness. This effect is generally attributed to the rotational modulation of the ablation rate, which is caused by the time-varying cross…
Long period comet C/2014 B1 (Schwartz) exhibits a remarkable optical appearance, like that of a discus or bi-convex lens viewed edgewise. Our measurements in the four years since discovery reveal a unique elongated dust coma whose…
We present the history of investigation of the dynamical properties of pairs and groups of genetically related long-period comets (other than the Kreutz sungrazing system). Members of a comet pair or group move in nearly identical orbits…
Comet 17P/Holmes underwent a massive outburst in 2007 Oct., brightening by a factor of almost a million in under 48 hours. We used infrared images taken by the Wide-Field Survey Explorer mission to characterize the comet as it appeared at a…
For a solar-like star, the surface rotation evolves with time, allowing in principle to estimate the age of a star from its surface rotation period. Here we are interested in measuring surface rotation periods of solar-like stars observed…
Three dimensional electron density distributions in the solar corona are reconstructed for 100 Carrington Rotations (CR 2054$-$2153) during 2007/03$-$2014/08 using the spherically symmetric method from polarized white-light observations…
Using long-term X-ray observations, we present the short-term and long-term X-ray variability analysis of the ultra-fast rotating active star AB Dor. Flaring events are common in X-ray observations of AB Dor and occupy a substantial portion…
Magnetic activity cycles are an important phenomenon in both the Sun and other stars. The shape of the solar cycle is commonly characterised by a fast rise and a slower decline, but not much attention has been paid to the shape of cycles in…
Light curves of solar-type stars often show gradual fluctuations due to rotational modulation by magnetic features (starspots and faculae) on stellar surfaces. Two quantitative measures of modulated light curves are employed as the proxies…
We present a photometric and dynamical study of comet C/2010 U3 (Boattini), which was seen active in prediscovery data as early as 2005 November at a new inbound record heliocentric distance $r_{\rm H} = 25.8$ au. Two outburst events around…