Search Publications
Modification history of the Harmakhis Vallis outflow channel, Mars, based on CTX-scale photogeologic mapping and crater count dating
Kostama, V. -P.; Kukkonen, S.
Harmakhis Vallis is one of the four major outflow channel systems (Dao, Niger, Harmakhis, and Reull Valles) that cut the eastern rim region of the Hellas basin, the largest well-preserved impact structure on Mars. The structure of Harmakhis Vallis and the volume of its head depression, as well as earlier dating studies of the region, suggest that …
Variability search in M 31 using principal component analysis and the Hubble Source Catalogue
Hatzidimitriou, D.; Gavras, P.; Bonanos, A. Z. +4 more
Principal component analysis (PCA) is being extensively used in Astronomy but not yet exhaustively exploited for variability search. The aim of this work is to investigate the effectiveness of using the PCA as a method to search for variable stars in large photometric data sets. We apply PCA to variability indices computed for light curves of 18 1…
Bi-Abundance Ionisation Structure of the Wolf-Rayet Planetary Nebula PB 8
Danehkar, A.
The planetary nebula PB 8 around a [WN/WC]-hybrid central star is one of planetary nebulae with moderate abundance discrepancy factors (ADFs 2-3), which could be an indication of a tiny fraction of metal-rich inclusions embedded in the nebula (bi-abundance). In this work, we have constructed photoionisation models to reproduce the optical and infr…
A Subarcsecond Near-infrared View of Massive Galaxies at z > 1 with Gemini Multi-conjugate Adaptive Optics
Surace, J. A.; Farrah, D.; Vaccari, M. +14 more
We present images taken using the Gemini South Adaptive Optics Imager (GSAOI) with the Gemini Multi-conjugate Adaptive Optics System (GeMS) in three 2 arcmin2 fields in the Spitzer Extragalactic Representative Volume Survey. These GeMS/GSAOI observations are among the first ≈0.″1 resolution data in the near-infrared spanning extragalact…
In-depth study of long-term variability in the X-ray emission of the Be/X-ray binary system AX J0049.4-7323
Santangelo, A.; Ducci, L.; Romano, P. +3 more
AX J0049.4-7323 is a Be/X-ray binary in the Small Magellanic Cloud hosting a 750 s pulsar which has been observed over the last 17 years by several X-ray telescopes. Despite numerous observations, little is known about its X-ray behaviour. Therefore, we coherently analysed archival Swift, Chandra, XMM-Newton, RXTE, and INTEGRAL data, and we compar…
The Lives of Stars: Insights from the TGAS-RAVE-LAMOST Data Set
Smith, Martin C.; Vickers, John J.
In this paper, we investigate how the chemical and kinematic properties of stars vary as a function of age. Using data from a variety of photometric, astrometric, and spectroscopic surveys, we calculate the ages, phase space information, and orbits for ∼125,000 stars covering a wide range of stellar parameters. We find indications that the inner r…
The supernova-regulated ISM. IV. A comparison of simulated polarization with Planck observations
Juvela, M.; Käpylä, M. J.; Väisälä, M. S. +1 more
Context. Efforts to compare polarization measurements with synthetic observations from magnetohydrodynamics (MHD) models have previously concentrated on the scale of molecular clouds.
Aims: We extend the model comparisons to kiloparsec scales, taking into account hot shocked gas generated by supernovae and a non-uniform dynamo-generated magne…
Calibrating the James Webb Space Telescope Filters as Star Formation Rate Indicators
Moustakas, John; Armus, Lee; Brown, Michael J. I. +3 more
We have calibrated the 6.5 m James Webb Space Telescope (JWST) mid-infrared (MIR) filters as star formation rate (SFR) indicators, using JWST photometry synthesized from Spitzer spectra of 49 low-redshift galaxies, which cover a wider luminosity range than most previous studies. We use Balmer-decrement-corrected Hα luminosity and synthesized MIR p…
Solar flares, CMEs and solar energetic particle events during solar cycle 24
Pande, Bimal; Pande, Seema; Chandra, Ramesh +1 more
We present here a study of Solar Energetic Particle Events (SEPs) associated with solar flares during 2010-2014 in solar cycle 24. We have selected the flare events (≥GOES M-class), which produced SEPs. The SEPs are classified into three categories i.e. weak (proton intensity ≤ 1 pfu), minor (1 pfu < proton intensity < 10 pfu) and major (pro…
Coronal Electron Density Temperature and Solar Spectral Irradiance during Solar Cycles 23 and 24
Palacios, J.; Dal Lago, A.; Rodríguez Gómez, J. M. +1 more
Plasma parameters such as the electron density and temperature play a key role in the dynamics of the solar atmosphere. These characteristics are important in solar physics because they can help us to understand the physics of the solar corona, the ultimate goal being the reconstruction of the electron density and temperature distributions in the …