Search Publications
Variability and Star Formation in Leo T, the Lowest Luminosity Star-forming Galaxy Known Today
Cignoni, Michele; Marconi, Marcella; Ripepi, Vincenzo +5 more
We present results from the first combined study of variable stars and star formation history (SFH) of the Milky Way "ultra-faint" dwarf (UFD) galaxy Leo T, based on F606W and F814W multi-epoch archive observations obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. We have detected 14 variable stars in the galaxy.…
Dust and gas power spectrum in M 33 (HERM33ES)
Boquien, M.; Braine, J.; Calzetti, D. +18 more
Power spectra of deprojected images of late-type galaxies in gas or dust emission are very useful diagnostics of the dynamics and stability of their interstellar medium. Previous studies have shown that the power spectra can be approximated as two power laws, a shallow one on large scales (larger than 500 pc) and a steeper one on small scales, wit…
Characterization of new hard X-ray cataclysmic variables
Mukai, K.; de Martino, D.; Masetti, N. +5 more
Aims: We aim at characterizing a sample of nine new hard X-ray selected cataclysmic variable (CVs), to unambiguously identify them as magnetic systems of the intermediate polar (IP) type.
Methods: We performed detailed timing and spectral analysis by using X-ray, and simultaneous UV and optical data collected by XMM-Newton, complemented …
Rapid Sunspot Rotation Associated with the X2.2 Flare on 2011 February 15
Yang, Jiayan; Hong, Junchao; Zheng, Ruisheng +3 more
We present observations of sunspot evolution associated with the first X-class flare of the present solar cycle 24, which occurred in AR 11158 on 2011 February 15. The active region consisted of four emerging bipoles that showed complicated sunspot motion. The preceding spot of a bipole underwent the fastest movement. It not only passed through th…
Nonthermal X-rays from low-energy cosmic rays: application to the 6.4 keV line emission from the Arches cluster region
Decourchelle, A.; Maurin, G.; Tatischeff, V.
Context. The iron Kα line at 6.4 keV provides a valuable spectral diagnostic in several fields of X-ray astronomy. The line often results from the reprocessing of external hard X-rays by a neutral or low-ionized medium, but it can also be excited by impacts of low-energy cosmic rays.
Aims: This paper aims to provide signatures allowing identi…
Benchmarking atomic data for the CHIANTI atomic database: coronal lines observed by Hinode EIS
Del Zanna, G.
The coronal lines that are observable in the Hinode EUV Imaging Spectrometer (EIS) wavelengths are assessed with new atomic data that have recently become available for a range of important ions. EIS spectral lines are identified based on their spatial variation across different solar regions, their wavelengths, and their intensities. Two off-limb…
A Brightest Cluster Galaxy with an Extremely Large Flat Core
Donahue, Megan; Broadhurst, Tom; Moustakas, John +14 more
Hubble Space Telescope images of the galaxy cluster A2261, obtained as part of the Cluster Lensing And Supernova survey with Hubble, show that the brightest galaxy in the cluster, A2261-BCG, has the largest core yet detected in any galaxy. The cusp radius of A2261-BCG is 3.2 kpc, twice as big as the next largest core known, and ~3 × bigger than th…
Herschel/HIFI observations of O-rich AGB stars: molecular inventory
Menten, K. M.; Olofsson, H.; Marston, A. P. +17 more
Aims: Spectra, taken with the heterodyne instrument, HIFI, aboard the Herschel Space Observatory, of O-rich asymptotic giant branch (AGB) stars which form part of the guaranteed time key program HIFISTARS are presented. The aim of this program is to study the dynamical structure, mass-loss driving mechanism, and chemistry of the outflows from…
A Reverberation Lag for the High-ionization Component of the Broad-line Region in the Narrow-line Seyfert 1 Mrk 335
Skowron, J.; Kochanek, C. S.; Horne, Keith +37 more
We present the first results from a detailed analysis of photometric and spectrophotometric data on the narrow-line Seyfert 1 (NLS1) galaxy Mrk 335, collected over a 120 day span in the fall of 2010. From these data we measure the lag in the He II λ4686 broad emission line relative to the optical continuum to be 2.7 ± 0.6 days and the lag in the H…
The star formation history and dust content in the far outer disc of M31
Lewis, Geraint F.; McConnachie, Alan W.; Ibata, Rodrigo A. +7 more
We present a detailed analysis of two fields located 26 kpc (∼5 radial scalelengths) from the centre of M31 along the south-west semimajor axis of the disc. One field samples the major axis populations - the Outer Disc field - while the other is offset by ∼18 arcmin and samples the warp in the stellar disc - the warp field. The colour-magnitude di…