Search Publications
Suzaku Observations of the Cluster Outskirts and Intercluster Filament in the Triple Merger Cluster A98
Sarazin, Craig L.; Walker, Stephen; Randall, Scott W. +5 more
We present Suzaku observations of the Abell 98 (A98) triple galaxy cluster system and the purported intercluster filament. The three subclusters are expected to lie along a large-scale cosmic filament. With partial azimuthal coverage of the northernmost cluster, we find that the inferred entropy profile of this relatively low-mass cluster (kT ≈ 2.…
Starspots, chromospheric emission lines, and flares of zero-age main-sequence stars
Itoh, Yoichi; Oasa, Yumiko; Yamashita, Mai
Zero-age main-sequence (ZAMS) stars are considered to have enormous starspots and show strong chromospheric emission lines because of their strong surface magnetic field. We discuss the dynamo activities of ZAMS stars with respect to their periodic light variation caused by a starspot and with respect to the strength of the chromospheric emission …
The Astrometric Performance Test of 80 cm Telescope at Yaoan Station and Precise CCD Positions of Apophis
Guo, Bifeng; Peng, Qingyu; Chen, Ying +4 more
The 80 cm azimuthal telescope has newly been mounted at Yaoan Station, Purple Mountain Observatory since 2018. The astrometric performance of the telescope is tested in the following three aspects. (a) The geometric distortion of its CCD attached. It is stable in both a single epoch and multi epochs. Eight distortion solutions are derived over abo…
Probabilistic Prediction of Dst Storms One-Day-Ahead Using Full-Disk SoHO Images
Hu, A.; Shneider, C.; Tiwari, A. +1 more
We present a new model for the probability that the disturbance storm time (Dst) index exceeds -100 nT, with a lead time between 1 and 3 days. Dst provides essential information about the strength of the ring current around the Earth caused by the protons and electrons from the solar wind, and it is routinely used as a proxy for geomagnetic storms…
Locations and Morphologies of Jellyfish Galaxies in A2744 and A370
Richard, Johan; Fritz, Jacopo; Vulcani, Benedetta +11 more
We present a study of the orbits, environments, and morphologies of 13 ram-pressure stripped galaxies in the massive, intermediate redshift (z ~ 0.3-0.4) galaxy clusters A2744 and A370, using MUSE integral-field spectroscopy and Hubble Space Telescope imaging from the Frontier Fields Program. We compare different measures of the locations and morp…
The 2019 Outburst of the 2005 Classical Nova V1047 Cen: A Record Breaking Dwarf Nova Outburst or a New Phenomenon?
Mukai, K.; Sokoloski, J. L.; Udalski, A. +28 more
We present a detailed study of the 2019 outburst of the cataclysmic variable V1047 Cen, which hosted a classical nova eruption in 2005. The peculiar outburst occurred 14 yr after the classical nova event and lasted for more than 400 days, reaching an amplitude of around 6 magnitudes in the optical. Early spectral follow-up revealed what could be a…
CO(2-1)/CO(1-0) Line Ratio on a 100 Parsec Scale in the Nearby Barred Galaxy NGC 1300
Asada, Yoshihisa; Ohta, Kouji; Egusa, Fumi +3 more
CO(2-1) emission is often used as a tracer of giant molecular clouds (GMCs) as an alternative to CO(1-0) emission in recent years. Therefore, understanding the environmental dependence of the line ratio of CO(2-1)/CO(1-0), R 21, on the GMC scale is important to accurately estimate the mass of GMCs. We thus measured R 21 in th…
Lithium, masses, and kinematics of young Galactic dwarf and giant stars with extreme [α/Fe] ratios
Charbonnel, C.; Prantzos, N.; Borisov, S.
Context. Recent spectroscopic explorations of large Galactic stellar samples stars have revealed the existence of red giants with [α/Fe] ratios that are anomalously high, given their relatively young ages.
Aims: We revisit the GALAH DR3 survey to look for both dwarf and giant stars with extreme [α/Fe] ratios, that is, the upper 1% in the [α/F…
On the Dwarf Irregular Galaxy NGC 6822. I. Young, Intermediate, and Old Stellar Populations
Salaris, Maurizio; Nonino, Mario; Dall'Ora, Massimo +13 more
We present accurate and deep multiband (g, r, i) photometry of the Local Group dwarf irregular galaxy NGC 6822. The images were collected with wide-field cameras at 2 m/4 m (INT, CTIO, CFHT) and 8 m class telescopes (Subaru) covering a 2 deg2 field of view across the center of the galaxy. We performed point-spread function photometry of…
Line-of-sight Elongation and Hydrostatic Mass Bias of the Frontier Fields Galaxy Cluster Abell 370
Koekemoer, Anton M.; Oguri, Masamune; Umetsu, Keiichi +6 more
We present a detailed weak-lensing and X-ray study of the Frontier Fields galaxy cluster Abell 370, one of the most massive known lenses on the sky, using wide-field BR C z' Subaru/Suprime-Cam and Chandra X-ray observations. By combining two-dimensional (2D) shear and azimuthally averaged magnification constraints derived from Subaru da…