Search Publications
An interferometric SETI observation of Kepler-111 b
Gajjar, Vishal; Garrett, Michael A.; Wandia, Kelvin +8 more
The application of very long baseline interferometry (VLBI) to the search for extraterrestrial intelligence (SETI) has been limited to date, despite the technique offering many advantages over traditional single-dish SETI observations. In order to further develop interferometry for SETI, we used the European VLBI network (EVN) at 21 cm to observe …
New photometric solutions of contact binaries HX UMa and FP Boo
Yıldırım, M. F.
By using different databases (TESS, SuperWASP, KWS and ASAS-SN), light curve analyzes of HX UMa and FP Boo systems were performed, and the changes in the orbital period of the systems were also examined. The light curve analyzes of the systems were conducted simultaneously with the radial velocities using the Wilson and Devinney (WD) code. As a re…
Dark halos around solar active regions. I. Emission properties of the dark halo around NOAA 12706
Andretta, V.; Del Zanna, G.; Murabito, M. +1 more
Context. Dark areas around active regions (ARs) were first observed in chromospheric lines more than a century ago and are now associated with the Hα fibril vortex around ARs. Nowadays, large areas surrounding ARs with reduced emission relative to the quiet Sun (QS) are also observed in spectral lines emitted in the transition region (TR) and the …
NGC 4117: A New Compton-thick AGN Revealed by Broadband X-Ray Spectral Analysis
Mohanadas, Pavithra; Annuar, Adlyka
In this paper, we present the broadband (0.5-195 keV) X-ray spectral analysis for one of the newly detected AGNs in the Swift-BAT 105 month Hard X-ray Survey Catalog, NGC 4117. According to our ongoing research on low luminosity AGNs from the Swift-BAT 105 month catalog, we examine whether they are indeed low luminosity or heavily obscured AGNs. O…
An astrometric approach to measuring the colour of an object
Lin, F. R.; Peng, Q. Y.; Guo, B. F. +1 more
The colour of a star is a critical feature to reflect its physical property such as the temperature. The colour index is usually obtained via absolute photometry, which is demanding for weather conditions and instruments. In this work, we present an astrometric method to measure the catalogue-matched colour index of an object based on the effect o…
Photometric calibration in u-band using blue halo stars
von der Linden, Anja; Liang, Shuang
We develop a method to calibrate u-band photometry based on the observed colour of blue Galactic halo stars. The Galactic halo stars belong to an old stellar population of the Milky Way and have relatively low metallicity. The 'blue tip' of the halo population - the main sequence turn-off (MSTO) stars - is known to have a relatively uniform intrin…
G 68-34: A Double-lined M-dwarf Eclipsing Binary in a Hierarchical Triple System
Charbonneau, David; Pass, Emily K.
Using high-resolution spectra from the Tillinghast Reflector Echelle Spectrograph and photometry from sector 56 of the Transiting Exoplanet Survey Satellite, we report that the nearby M dwarf G 68-34 is a double-lined eclipsing binary. The pair is spin-orbit synchronized with a period of 0.655 days. The light curve shows significant spot modulatio…
A Catalog of Collected Debris Disks: Properties, Classifications and Correlations between Disks and Stars/Planets
Liu, Qiong; Liao, Neng-Hui; Cao, Peng-Cheng +2 more
We have collected a catalog of 1095 debris disks with properties and classification (resolved, planet, gas) information. From the catalog, we defined a less biased sample with 612 objects and presented the distributions of their stellar and disk properties to search for correlations between disks and stars. We found debris disks were widely distri…
A possible mechanism for the formation of an eastward moving auroral spiral
Grigorenko, Elena E.; Kronberg, Elena A.; Partamies, Noora +1 more
The generation process of auroral spirals is described by different theories varying for their morphology and surrounding conditions. Here, a possible mechanism is proposed for an eastward moving auroral spiral, which was observed in Tromsø, Norway, during the expansion phase of a substorm on 18 September 2013. Measurements from the THEMIS-A and C…
Spectral Clustering of CRISM Datasets in Jezero Crater Using UMAP and k-Means
Thomas, Nicolas; Rossi, Angelo Pio; Fernandes, Michael +2 more
In this paper, we expand upon our previous research on unsupervised learning algorithms to map the spectral parameters of the Martian surface. Previously, we focused on the VIS-NIR range of hyperspectral data from the CRISM imaging spectrometer instrument onboard NASA's Mars Reconnaissance Orbiter to relate to other correspondent imager data sourc…