Search Publications
The SPHERE view of multiple star formation
Gratton, Raffaele; Bonavita, Mariangela; Marzari, Francesco +1 more
While a large fraction of the stars are in multiple systems, our understanding of the processes leading to the formation of these systems is still inadequate. Given the large theoretical uncertainties, observation plays a basic role. Here we discuss the contribution of high contrast imaging, and more specifically of the SPHERE instrument at the ES…
Stellar Magnetic Activity Measure Based on IUE Mg II h+k Emission Lines of Main-Sequence G Stars
Choi, Hwajin; Yi, Yu; Kim, Dowoon
Stellar magnetic activity is important for formulating the evolution of the star. To represent the stellar magnetic activity, the S index is defined using the Ca II H+K flux measure from the Mount Wilson Observatory. Mg II lines are generated in a manner similar to the formation of Ca II lines, which are more sensitive to weak chromospheric activi…
HD 183986: A High-contrast SB2 System with a Pulsating Component
Gajdoš, Pavol; Vaňko, Martin; Pribulla, Theodor +7 more
There is a small group of peculiar early-type stars on the main sequence that show different rotation velocities from different spectral lines. This inconsistency might be due to the binary nature of these objects. We aim to verify this hypothesis by a more detailed spectroscopic and photometric investigation of one such object: HD 183986. We obta…
Lack of evidence for paleolakes in the Aeolis Dorsa region, Mars; a mapping investigation
Burr, D. M.; Peel, S. E.
The discovery of impact crater paleolakes, like the discoveries of ancient fluvial valleys, has been instrumental in our developing understanding of the history of water on Mars. Numerous and varied inverted paleo-fluvial deposits have been found within the westernmost lobes (Aeolis and Zephyria Plana) of the Medusae Fossae Formation, ∼800 km east…
A study of the characteristic properties of SEP events observed by SOHO ERNE during solar cycle 24
Biji, M. S.; Prince, P. R.
Properties and association of Solar Energetic Particle (SEP) events with their solar sources during the 24th solar cycle were examined. SEPs observed by SOHO ERNE were used. SEP properties include solar release time, peak proton flux and total fluence in different energy channels. Solar release times of SEP events were found out using Velocity Dis…
Investigating the Origin of X-Ray Jets: A Case Study of Four Hybrid Morphology MOJAVE Blazars
Baum, Stefi A.; O'Dea, Christopher P.; Marshall, Herman L. +3 more
We carried out Chandra, Hubble Space Telescope (HST), and Very Large Array observations of four MOJAVE blazars that have previously been classified as hybrid (FR I/II) blazars in terms of radio morphology but not total radio power. The motivation of this study is to determine the X-ray emission mechanism in jets, these being different in FR I and …
Makine Öğrenmesi Yöntemiyle Keşfedilen Seçilmiş Açık Kümelerin Detaylı Analizi
Ülgen, Eyüp Kaan; Ak, Tansel; Akbulut, Burcu
Bu çaılşmada Gaia uydusunun erken üçüncü veri sürümü (Gaia EDR3) kataloğundaki astrometrik ve fotometrik verilerinden itibaren makine öğrenmesi yöntemiyle keşfedilen ve literatürde detaylı çalışması bulunmayan UPK 51, UPK 350, UPK 579 ve UPK 599 açık kümelerinin Gaia EDR3 ve 2MASS verileri kullanılarak astrometrik ve astrofizik parametreleri tayin…
Observations of a Solar Energetic Particle Event From Inside and Outside the Coma of Comet 67P
Coates, A. J.; Palmerio, E.; Jones, G. H. +12 more
We analyze observations of a solar energetic particle (SEP) event at Rosetta's target comet 67P/Churyumov-Gerasimenko during 6-10 March 2015. The comet was 2.15 AU from the Sun, with the Rosetta spacecraft approximately 70 km from the nucleus placing it deep inside the comet's coma and allowing us to study its response. The Eastern flank of an int…
A list of guest‑star records in Korean history and their possible counterparts
An, Hongjun; Park, Jaegeun; Jeon, Junhyeok
We report on guest‑star events recorded in Korean history in the period between A.D. 154 and 1807. We search five books, namely Joseonwangjosillok, Seungjeongwonilgi, Jeungbomoonheonbigo, Goryeosa, and Samguksagi for "guest star" and find 37 events. Seventeen of the guest stars are almost certainly comets as identified previously and are not astro…
Classification of 3 accreting binaries with VLT/X-Shooter spectra
Chaty, S.; Tomsick, J. A.; Fortin, F. +1 more
Since its launch, the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite has discovered hundreds of X-ray sources, many of which lack proper classification. This mission also led to the discovery of new categories of high mass X-ray binaries (HMXB). We use the spectra of the X-Shooter instrument at the Very Large Telescope (VLT) …