Search Publications
Linear spectropolarimetric analysis of fairall 9 with VLT/FORS2
Mazzei, Paola; D'Onofrio, Mauro; Czerny, Bożena +10 more
The quasar main sequence appears to be an incredibly powerful tool to organize the diversity in large samples of type-1 quasars but the most important physical parameters governing it are still unclear. Here, we investigate the origin of the broadening and of a defining feature of Population B sources: a strong redward asymmetry of the Balmer emis…
Identification confusion and blending concealment in the SDSS-DR16 Quasar catalogues - 40 new quasars and 82 false quasars identified
Flesch, Eric Wim
The SDSS-DR16 Quasar Superset and pipeline catalogues are searched for undeclared quasars that were concealed by or confused with other objects, usually due to incomplete deblending. 40 such quasars with redshifts are found and herewith presented. Also, 82 entries in the SDSS-DR16Q main quasar catalogue are shown to be non-quasars, some also due t…
Evolution of timing and spectral characteristics of 4U 1901+03 during its 2019 outburst using the Swift and NuSTAR observatories
Maitra, Chandreyee; Beri, Aru; Girdhar, Tinku +1 more
We report the results from a detailed timing and spectral study of a transient X-ray pulsar, 4U 1901+03 during its 2019 outburst. We performed broadband spectroscopy in the 1-70 $\rm keV$ energy band using four observations made with Swift and NuSTAR at different intensity levels. Our timing results reveal the presence of highly variable pulse pro…
New members of Cygnus OB2 from Gaia DR2
Orellana, R. B.; De Biasi, M. S.; Paíz, L. G.
Due to the high quality of Gaia DR2 stellar parallaxes and proper motions, we can study the Cygnus OB2 region up to G = 17.5 mag in circular region centred at (l, b) = (79.8°, +0.8°) of radius 1°. We detect four overdensities in the Vector Point Diagram. We apply a parametric model of the proper motion distribution and determine their mean proper …
Multipoint remote and in situ observations of interplanetary coronal mass ejection structures during 2011 and associated geomagnetic storms
Teriaca, Luca; Srivastava, Nandita; Mishra, Wageesh +1 more
We present multipoint remote and in situ observations of interplanetary coronal mass ejection (ICME) structures during the year 2011. The selected ICMEs arrived at Earth on 2011 March 11 and 2011 August 6, and led to geomagnetic storms. Around the launch of these CMEs from the Sun, the coronagraphs onboard STEREO-Aand-B and SOHO enabled the CMEs t…
Mass-radius relation of intermediate-age disc super star clusters of M82
Mayya, Y. D.; Rosa-González, D.; Puerari, I. +1 more
We present a complete set of structural parameters for a sample of 99 intermediate-age super star cluster (SSCs) in the disc of M82, and carry out a survival analysis using the semi-analytical cluster evolution code EMACSS. The parameters are based on the profile-fitting analysis carried out in previous work, with the mass-related quantities deriv…
Environmental effects on AGN activity via extinction-free mid-infrared census
Hashimoto, Tetsuya; Goto, Tomotsugu; Kim, Seong Jin +20 more
How does the environment affect active galactic nucleus (AGN) activity? We investigated this question in an extinction-free way by selecting 1120 infrared (IR) galaxies in the AKARI North Ecliptic Pole Wide field at redshift z ≤ 1.2. A unique feature of the AKARI satellite is its continuous nine-band IR filter coverage, providing us with an unprec…
The temperatures of red supergiants in low-metallicity environments
Kudritzki, Rolf-Peter; Davies, Ben; González-Torà, Gemma +1 more
The temperatures of red supergiants (RSGs) are expected to depend on metallicity (Z) in such a way that lower Z RSGs are warmer. In this work, we investigate the Z-dependence of the Hayashi limit by analysing RSGs in the low-Z galaxy Wolf-Lundmark-Mellote, and compare with the RSGs in the higher Z environments of the Small Magellanic Cloud and Lar…
Chandra grating spectroscopy of embedded wind shock X-ray emission from O stars shows low plasma temperatures and significant wind absorption
Leutenegger, Maurice A.; Cohen, David H.; Gagné, Marc +4 more
We present a uniform analysis of six examples of embedded wind shock (EWS) O star X-ray sources observed at high resolution with the Chandra grating spectrometers. By modelling both the hot plasma emission and the continuum absorption of the soft X-rays by the cool, partially ionized bulk of the wind we derive the temperature distribution of the s…
High-contrast and resolution near-infrared photometry of the core of R136
Langlois, Maud; Buckner, Anne S. M.; Khorrami, Zeinab +8 more
We present the sharpest and deepest near-infrared photometric analysis of the core of R136, a newly formed massive star cluster at the centre of the 30 Doradus star-forming region in the Large Magellanic Cloud. We used the extreme adaptive optics of the SPHERE focal instrument implemented on the ESO Very Large Telescope and operated in its IRDIS i…