Search Publications
Joint Suzaku and Chandra observations of the MKW4 galaxy group out to the virial radius
Kraft, Ralph; Gastaldello, Fabio; Sarkar, Arnab +5 more
We present joint Suzaku and Chandra observations of MKW4. With a global temperature of 1.6 keV, MKW4 is one of the smallest galaxy groups that have been mapped in X-rays out to the virial radius. We measure its gas properties from its centre to the virial radius in the north, east, and north-east directions. Its entropy profile follows a power law…
Diagnostics of homologous solar-surge plasma as observed by IRIS and SDO
Kayshap, Pradeep; Tripathi, Sharad C.; Singh Payal, Rajdeep +1 more
Surges have regularly been observed in mostly H α 6563 Å and Ca II 8542 Å. However, surge responses to other prominent lines of the interface region (Mg II k 2796.35 Å and h 2803.52 Å, O IV 1401.15 Å, Si IV 1402.77 Å) are not well studied. Here, the evolution and kinematics of six homologous surges are analysed using IRIS and AIA observations. The…
Search for giant planets around seven white dwarfs in the Hyades cluster with the Hubble Space Telescope
Brandner, Wolfgang; Kopytova, Taisiya; Zinnecker, Hans
Only a small number of exoplanets have been identified in stellar cluster environments. We initiated a high angular resolution direct imaging search using the Hubble Space Telescope (HST) and its Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument for self-luminous giant planets in orbit around seven white dwarfs in the 625 Myr …
Kepler K2 Campaign 9 - I. Candidate short-duration events from the first space-based survey for planetary microlensing
Poleski, R.; Mao, S.; Penny, M. T. +6 more
We present the first short-duration candidate microlensing events from the Kepler K2 mission. From late April to early July 2016, Campaign 9 of K2 obtained high temporal cadence observations over a 3.7 deg2 region of the Galactic bulge. Its primary objectives were to look for evidence of a free-floating planet (FFP) population using mic…
Hamilton's Object - a clumpy galaxy straddling the gravitational caustic of a galaxy cluster: constraints on dark matter clumping
Griffiths, Richard E.; Villforth, Carolin; Wagner, Jenny +3 more
We report the discovery of a 'folded' gravitationally lensed image, 'Hamilton's Object', found in a HST image of the field near the active galactic nucleus SDSS J223010.47-081017.8 (which has redshift 0.62). The lensed images are sourced by a galaxy at a spectroscopic redshift of 0.8200 ± 0.0005 and form a fold configuration on a caustic caused by…
The nearby magnetic cool DZ white dwarf PM J08186-3110
Vennes, Stéphane; Allard, Nicole F.; Kawka, Adela +2 more
We present an analysis of photometric, spectroscopic, and spectropolarimetric data of the nearby, cool, magnetic DZ white dwarf PM J08186-3110. High-dispersion spectra show the presence of Zeeman splitted spectral lines due to the presence of a surface average magnetic field of 92 kG. The strong magnesium and calcium lines show extended wings shap…
Metallicity and X-ray luminosity variations in NGC 922
Zezas, A.; Wolter, A.; Fruscione, A. +3 more
We present a systematic study of the metallicity variations within the collisional ring galaxy NGC 922 based on long-slit optical spectroscopic observations. We find a metallicity difference between star-forming regions in the bulge and the ring, with metallicities ranging from almost solar to significantly sub-solar ( $\rm {[12+\log (O/H)]\sim 8.…
HCT/HESP study of two carbon stars from the LAMOST survey
Shi, Jianrong; Shejeelammal, J.; Goswami, Aruna
Carbon stars, enhanced in carbon and neutron-capture elements, provide a wealth of information about the nucleosynthesis history of the Galaxy. In this work, we present the first ever detailed abundance analysis of the carbon star LAMOSTJ091608.81+230734.6 and a detailed abundance analysis of neutron-capture elements for the object LAMOSTJ151003.7…
AB Aurigae: possible evidence of planet formation through the gravitational instability
Cadman, James; Hall, Cassandra; Rice, Ken
Recent observations of the protoplanetary disc surrounding AB Aurigae have revealed the possible presence of two giant planets in the process of forming. The young measured age of 1-4 Myr for this system allows us to place strict time constraints on the formation histories of the observed planets. Hence, we may be able to make a crucial distinctio…
Middle aged γ-ray pulsar J1957+5033 in X-rays: pulsations, thermal emission, and nebula
Karpova, A. V.; Zyuzin, D. A.; Suleimanov, V. F. +2 more
We analyse new XMM-Newton and archival Chandra observations of the middle-aged γ-ray radio-quiet pulsar J1957+5033. We detect, for the first time, X-ray pulsations with the pulsar spin period of the point-like source coinciding by position with the pulsar. This confirms the pulsar nature of the source. In the 0.15-0.5 keV band, there is a single p…