Search Publications
Tracking the spectral properties of ESO 511-G030 across different epochs
Bianchi, S.; Cappi, M.; Done, C. +14 more
The Type 1 active galactic nucleus (AGN) ESO 511-G030, a formerly bright and soft excess dominated source, was observed in 2019 in the context of a multi-wavelength monitoring campaign. In the new exposures, the source was found to be in a flux state approximately ten times lower than archival exposures and without any trace of the soft excess. In…
The Deformation of an Erupting Magnetic Flux Rope in a Confined Solar Flare
Liu, Yang; Zhang, Liang; Chen, Yao +7 more
Magnetic flux ropes (MFRs), sets of coherently twisted magnetic field lines, are believed as core structures of various solar eruptions. Their evolution plays an important role to understand the physical mechanisms of solar eruptions, and can shed light on adverse space weather near the Earth. However, the erupting MFRs are occasionally prevented …
Searching for Compact Object Candidates from LAMOST Time-domain Survey of Four K2 Plates
Liu, Jifeng; Gu, Wei-Min; Wang, Song +3 more
The time-domain (TD) surveys of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) yield high-cadence radial velocities, paving a new avenue to study binary systems including compact objects. In this work, we explore LAMOST TD spectroscopic data of four K2 plates and present a sample of six single-lined spectroscopic binaries t…
An Earth-sized Planet around an M5 Dwarf Star at 22 pc
Ikuta, Kai; Cochran, William D.; Redfield, Seth +46 more
We report on the discovery of an Earth-sized transiting planet (R p = 1.015 ± 0.051 R ⊕) in a P = 4.02 day orbit around K2-415 (EPIC 211414619), an M5V star at 22 pc. The planet candidate was first identified by analyzing the light-curve data obtained by the K2 mission, and it is here shown to exist in the most recent data …
Characterizing abundance-age relations of GALAH stars using oxygen-enhanced stellar models
Wu, Yaqian; Xiang, Maosheng; Bi, Shaolan +3 more
Main-sequence turn-off (MSTO) stars and subgiant stars are good tracers of Galactic populations. We present a study of 41 034 MSTO and subgiant stars from the GALAH survey. Using a grid of stellar models that accounts for the variation of O abundances, we determine their ages with a median age uncertainty of ~9.4 per cent. Our analysis reveals tha…
Observations of Mini Coronal Dimmings Caused by Small-scale Eruptions in the Quiet Sun
Wang, Rui; Liu, Ying D.; Hu, Huidong +1 more
Small-scale eruptions could play an important role in coronal heating, generation of solar energetic particles (SEPs), and mass source of the solar wind. However, they are poorly observed, and their characteristics, distributions, and origins remain unclear. Here a mini coronal dimming was captured by the recently launched Solar Orbiter spacecraft…
NuSTAR Observations of Four Mid-IR-Selected Dual AGN Candidates in Galaxy Mergers
Ricci, Claudio; Blecha, Laura; Satyapal, Shobita +5 more
Mergers of galaxies are a ubiquitous phenomenon in the universe and represent a natural consequence of the "bottom-up" mass accumulation and galaxy evolution cosmological paradigm. It is generally accepted that the peak of active galactic nucleus (AGN) accretion activity occurs at nuclear separations of ≲10 kpc for major mergers. Here we present n…
Assessment of the arrival signatures of the March 2012 CME–CME interaction event with respect to Mercury, Venus, Earth, STEREO-B, and Mars locations
Thampi, R. Satheesh; Soni, Shirsh Lata; Selvakumaran, R.
In March 2012, favourable positions of Mercury, Venus, Earth, Mars, and STEREO-B in the inner solar system provided an opportunity to understand the global structure and the propagation of a CME across the inner solar system. On March 7, 2012, the Sun ejected two very fast CMEs from solar active region NOAA AR11489, which were accompanied by two X…
The C/N ratio from FUV spectroscopy as a constraint on evolution of the dwarf nova HS 0218 + 3229
Szkody, Paula; El-Badry, Kareem; Gänsicke, Boris T. +8 more
White dwarfs that accrete from non-degenerate companions show anomalous carbon and nitrogen abundances in the photospheres of their stellar components have been postulated to be descendants of supersoft X-ray binaries. Measuring the carbon-to-nitrogen abundance ratio may provide constraints on their past evolution. We fit far-ultraviolet spectrosc…
TESS Asteroseismic Analysis of HD 76920: The Giant Star Hosting an Extremely Eccentric Exoplanet
Li, Yaguang; Chaplin, William J.; Kane, Stephen R. +30 more
The Transiting Exoplanet Survey Satellite (TESS) mission searches for new exoplanets. The observing strategy of TESS results in high-precision photometry of millions of stars across the sky, allowing for detailed asteroseismic studies of individual systems. In this work, we present a detailed asteroseismic analysis of the giant star HD 76920 hosti…