Search Publications
Concurrence of a Kelvin-Helmholtz instability and Kármán vortex street in the Sun's corona
Long, David M.; Fu, Hui; Li, Bo +4 more
Context. Instabilities are crucial to understanding the mass transportation and energy transformation in the solar atmosphere. Observations of the concurrence among the Kelvin-Helmholtz instability (KHI) and Kármán vortex street (KVS) in conditions as extreme as the Sun's corona have yet to be reported.
Aims: We aim to find evidence of a conc…
First r-process enhanced star confirmed as a member of the Galactic bulge
Schultheis, M.; Ryde, N.; Rich, R. M. +4 more
Aims: Stars with strong enhancements of r-process elements are rare and tend to be metal-poor, generally with [Fe/H] < −2 dex, and located in the halo. In this work, we aim to investigate a candidate r-process enriched bulge star with a relatively high metallicity of [Fe/H] ~ − 0.65 dex and to compare it with a previously published r-rich …
Characteristics of X-class flares of solar cycles 23 and 24 in X-ray and EUV bands
Bhardwaj, Anil; Kumar, A.; Chakrabarty, D. +4 more
The characteristics of X-class flares of solar cycles 23 and 24 are examined based on the soft X-ray (0.1-0.8 nm) and EUV (26-34 nm) light curves. First, the commonly used correction factors for the center-to-limb variation of EUV flux are compared. Subsequently, enhancements in X-ray and EUV levels are used to calculate the relative apportionment…
NGTS clusters survey - IV. Search for Dipper stars in the Orion Nebular Cluster
Ramsay, Gavin; Wheatley, Peter J.; Henderson, Beth A. +13 more
The dipper is a novel class of young stellar object associated with large drops in flux on the order of 10-50 per cent lasting for hours to days. Too significant to arise from intrinsic stellar variability, these flux drops are currently attributed to disc warps, accretion streams, and/or transiting circumstellar dust. Dippers have been previously…
Transit timing variation analysis of the low-mass brown dwarf KELT-1 b
Southworth, J.; Mancini, L.; Evans, D. F. +8 more
We investigate whether there is a variation in the orbital period of the short-period brown dwarf-mass KELT-1 b, which is one of the best candidates to observe orbital decay. We obtain 19 high-precision transit light curves of the target using six different telescopes. We add all precise and complete transit light curves from open databases and th…
On structural properties of Comet 67/P dust particles collected in situ by ROSETTA/COSIMA from observations of electrical fragmentation
Klaus, Hornung; Eva, Maria Mellado; Oliver, J. Stenzel +20 more
After landing on the target, the kinetic energy can be dissipated within the fragment if it consists of many elements (as in the example of the Kerttu-Ender fragment, Fig. 2). If it consists of only a few elements, as is the case for most fragments traveling longer distances, the kinetic energy is dissipated by rolling. In the case of impact fragm…
3D structure of H II regions in the star-forming complex S254-S258
Moiseev, Alexei V.; Kirsanova, Maria S.; Boley, Paul A.
The S254-258 star-forming complex is a place of massive star formation where five OB-stars have created H II regions, visible as optical nebulae, and disrupted the parental molecular gas. In this work, we study the 3D structure of these H II regions using optical spectroscopy and tunable-filter photometry with the 6- and 1-m telescopes of the Spec…
Blanco DECam Bulge Survey (BDBS). VI. Extinction Maps Toward Southern Galactic Bulge Globular Clusters
Clarkson, William I.; Rich, R. Michael; Kunder, Andrea +9 more
We present wide-field, high resolution maps of the color excess for 14 globular clusters toward the Southern Galactic bulge. The maps were derived using Gaia EDR3 astrometry and stellar photometry from the Blanco DECam Bulge Survey, which is a deep, wide-field ugrizY photometric survey of the southern Galactic bulge. Comparisons with WISE 12 &micr…
Walkaway Star Candidates in IC 348 and Their Possible Birthplaces
Fang, Min; Herczeg, Gregory J.; Ren, Bin B. +2 more
Observations and theories reveal that star-forming regions eject their members during the early evolution of the cluster. We present an initial search for stars ejected from the young cluster IC 348 based on an analysis of Gaia EDR3 astrometry of previously identified members. We identify six candidate walkaway stars with projected velocities of 5…
The Effelsberg survey of FU Orionis and EX Lupi objects. II. H2O maser observations
Menten, K. M.; Ábrahám, P.; Kóspál, Á. +7 more
Context. FU Orionis (FUor) and EX Lupi (EXor) type objects are two groups of peculiar and rare pre-main sequence low-mass stars that are undergoing powerful accretion outbursts during their early stellar evolution. Although water masers are widespread in star-forming regions and serve as powerful probes of mass accretion and ejection on small scal…