Search Publications
The Sun's Seismic Radius as Measured from the Fundamental Modes of Oscillations and Its Implications for the TSI Variations
Hill, F.; Tripathy, S. C.; Jain, Kiran
In this Letter we explore the relationship between the solar seismic radius and total solar irradiance (TSI) during the last two solar cycles using the uninterrupted data from space-borne instruments on board the Solar and Heliospheric Observatory (SoHO) and the Solar Dynamics Observatory (SDO). The seismic radius is calculated from the fundamenta…
Penumbral Microjets in Sunspot Chromospheres: Evidence of Magnetic Reconnection
Katsukawa, Yukio
Parameters and models of the jets from Sanduleak's star in the LMC
Raga, A. C.; Noriega-Crespo, A.; Camps-Fariña, A.
Context. Angeloni and collaborators have discovered a bipolar jet extending out to 6 pc from "Sanduleak's star" in the Large Magellanic Cloud (LMC). This is the first angularly resolved stellar jet system that has been observed outside our Galaxy.
Aims: In this paper we use archival Hubble Space Telescope (HST) images of this jet in order to …
Small-Scale Activity Above the Penumbra of a Fast-Rotating Sunspot
Bharti, L.; Sobha, B.; Quintero Noda, C. +3 more
High-resolution observations of small-scale activity above the filamentary structure of a fast-rotating sunspot of NOAA Active Region 10930 are presented. The penumbral filament that intrudes into the umbra shows a central dark core and substructures. It almost approached another end of the umbra, like a light bridge. The chromospheric Ca II H ima…
The variable carbon star CGCS 6107
Nesci, R.; Rossi, C.; Ochner, P. +1 more
The spectroscopic and photometric variability of CGCS 6107 has been studied with four telescopes from 2015 to 2018. The star varied between R=11.4 and 14.2 mag with a time scale of 500 days. An appreciable color variation was observed, the star being bluer when brighter. H emission was present around maxima. The spectrum is that of an N type giant…
Spectroscopic EUV observations of impulsive solar energetic particle event sources
Innes, D. E.; Fludra, A.; Gómez-Herrero, R. +4 more
Context. Remote observations of solar flare ion acceleration are rather limited. Theoretical predictions for signatures of ion acceleration in extreme ultraviolet (EUV) line profiles have been made. Previous tests involve observations of flares with no evidence for energetic ions.
Aims: We aim to examine a source flare of impulsive (or 3…
Spectroscopic Investigations of Galactic Clusters with Associated Cepheid Variables. I. Polaris Cluster and α UMi.
Miroshnichenko, A. S.; Kovtyukh, V. V.; Danford, S. +4 more
We present the results of an analysis of the spectra of nine so called Polaris cluster A-FV stars obtained during 2016-2018. Radial velocities (RV) and GAIA DR 18 parallaxes-distances for these stars allow us to determine their membership in the cluster and to construct its 3D kinematic model. However Teff for four stars determined spec…
Multiple, short-lived "stellar prominences" on the O giant ξ Persei: a magnetic star?
Henrichs, H. F.; Sudnik, N.
We present strong evidence for a rotation period of 2.0406 d of the O giant ξ Persei, derived from the NIV λ1718 wind line in 12 yr of IUE data. We predict that ξ Per has a magnetic dipole field, with superposed variable magnetic prominences. Favorable dates for future magnetic measurements can be predicted. We also analysed time-resolv…
Experimental CCD Positional Observations of the Five Major Uranian Satellites
Wang, N.; Peng, Q. Y.; Xie, H. J. +1 more
Two hundred and forty-eight CCD frames, observed by using 1 m telescope at Yunnan Observatories for four consecutive nights, have been reduced to derive the precise positions of the five Uranian major satellites (Ariel, Umbriel, Titania, Oberon, and Miranda). The positions of satellites are measured with respect to the stars in Gaia DR1 (Data Rele…
VHE observations of binary systems performed with the MAGIC telescopes
Torres, Diego F.; Zanin, Roberta; Casares, Jorge +11 more
The improvement on the Imaging Air Cherenkov Technique (IACT) led to the discovery of a new type of sources that can emit at very high energies: the gamma-ray binaries. Only six systems are part of this exclusive class. We summarize the latest results from the observations performed with the MAGIC telescopes on different systems as the gamma-ray b…