838 research outputs found
The UV Excesses of Supernovae and the Implications for Studying Supernovae and Other Optical Transients
Supernovae (SNe), kilonovae (KNe), tidal disruption events (TDEs), optical
afterglows of gamma ray bursts (GRBs), and many other optical transients are
important phenomena in time-domain astronomy. Fitting the multi-band light
curves (LCs) or the synthesized (pseudo-)bolometric LCs can be used to
constrain the physical properties of optical transients. The (UV absorbed)
blackbody module is one of the most important modules used to fit the
multi-band LCs of optical transients having (UV absorbed) blackbody spectral
energy distributions (SEDs). We find, however, that the SEDs of some SNe show
UV excesses, which cannot be fitted by the model including a (UV absorbed)
blackbody module. We construct the bolometric LCs and employ the (cooling plus)
\Ni model to fit the constructed bolometric LCs, obtaining decent fits. Our
results demonstrate that the optical transients showing UV excesses cannot be
fitted by the multi-band models that include (UV-absorbed) blackbody module,
but can be well modeled by constructing and fitting their bolometric LCs.Comment: 9 pages, 4 figures, 1 table, submitted to Ap
SN 2018gk Revisited: the Photosphere, the Central Engine, And the Putative Dust
In this paper, we perform a comprehensive study for the physical properties
of SN 2018gk which is a luminous type IIb supernova (SN). We find that the
early-time photospheric velocity vary from a larger value to a smaller value
before the photosphere reach a temperature floor. We generalize the photosphere
modulus and fit the multi-band light curves (LCs) of SN 2018gk. We find that
the Ni mass model require M of Ni which is
larger than the derived ejecta mass ( M). Alternatively, we
use the magnetar plus Ni and the fallback plus Ni models to fit
the LCs of SN 2018gk, finding that the two models can fit the LCs. We favor the
magnetar plus Ni since the parameters are rather reasonable ( M, M which is smaller than the upper
limit of the value of the Ni mass can by synthesized by the
neutrino-powered core collapse SNe G which is comparable
to those of luminous and superluminous SNe studied in the literature, and
ms which is comparable to those of luminous SNe), while the
validity of the fallback plus Ni model depends on the accretion
efficiency (). Therefore, we suggest that SN 2018gk might be a SN IIb
mainly powered by a central engine. Finally, we confirm the NIR excesses of the
spectral energy distributions (SEDs) of SN 2018gk at some epochs and constrain
the physical properties of the putative dust using the blackbody plus dust
emission model.Comment: 26 pages, 11 figures, 5 tables, Accepted for publication in Ap
Pentaaqua(1H-benzimidazole-5,6-dicarboxylato-κN 3)nickel(II) pentahydrate
In the title mononuclear complex, [Ni(C9H4N2O4)(H2O)5]·5H2O, the NiII atom is six-coordinated by one N atom from a 1H-benzimidazole-5,6-dicarboxylate ligand and by five O atoms from five water molecules and displays a distorted octahedral geometry. Intermolecular O—H⋯O hydrogen-bonding interactions among the coordinated water molecules, solvent water molecules and carboxyl O atoms of the organic ligand and additional N—H⋯O hydrogen bonding lead to the formation of a three-dimensional supramolecular network
Diaquabis(4-carboxy-2-propyl-1H-imidazole-5-carboxylato-κ2 N 3,O 4)cobalt(II) N,N-dimethylformamide disolvate
In the title complex, [Co(C8H9N2O4)2(H2O)2]·2C3H7NO, the CoII cation (site symmetry ) is six-coordinated by two 5-carboxy-2-propyl-1H-imidazole-4-carboxylate ligands and two water molecules in a distorted octahedral environment. In the crystal structure, the complex molecules and dimethylformamide solvent molecules are linked by extensive O—H⋯O and N—H⋯O hydrogen bonding into sheets lying parallel to (21)
Hexaaquanickel(II) 4,4′-(1,2-dihydroxyethane-1,2-diyl)dibenzoate monohydrate
In the title compound, [Ni(H2O)6](C16H12O6)·H2O, the NiII cation is located on a mirror plane and is coordinated by six water molecules, two of which are also located on the mirror plane, in a distorted octahedral geometry. The 4,4′-(1,2-dihydroxyethane-1,2-diyl)dibenzoate anion is centrosymmetric with the mid-point of the central ethane C—C bond located on an inversion center. The uncoordinated water molecule is located on a mirror plane. Extensive O—H⋯O hydrogen bonding is present in the crystal structure
The Study of Dust Formation of Six Tidal Disruption Events
This paper investigates eleven (UV-)optical-infrared (IR) spectral energy
distributions (SEDs) of six tidal disruption events (TDEs), which are
ASASSN-14li, ASASSN-15lh, ASASSN-18ul, ASASSN-18zj, PS18kh, and ZTF18acaqdaa.
We find that all the SEDs show evident IR excesses. We invoke the blackbody
plus dust emission model to fit the SEDs, and find that the model can account
for the SEDs. The derived masses of the dust surrounding ASASSN-14li,
ASASSN-15lh, ASASSN-18ul, ASASSN-18zj, PS18kh, and ZTF18acaqdaa are
respectively ,
,
,
,
, and , if the dust is graphite (silicate). The
temperature of the graphite (silicate) dust of the six TDEs are respectively
\,K, \,K,
\,K, \,K, \,K, and
\,K. By comparing the derived temperatures to the
vaporization temperature of graphite (\,K) and silicate (\,K), we suggest that the IR excesses of PS18kh can be explained by
both the graphite and silicate dust, the rest five TDEs favor the graphite dust
while the silicate dust model cannot be excluded. Moreover, we demonstrate the
lower limits of the radii of the dust shells surrounding the six TDEs are
significantly larger than those of the radii of the photospheres at the first
epochs of SEDs, indicating that the dust might exist before the the TDEs
occurred.Comment: 13 pages, 4 figures, 4 tables, submitted to Ap
Poly[(μ4-tetrazole-1-acetato-κ4 N 3:N 4:O:O′)silver(I)]
In the title complex, [Ag(C3H3N4O2)]n, the AgI atom is four-coordinated in a slightly distorted tetrahedral coordination geometry by two N atoms from two tetrazole-1-acetate (tza) ligands and two O atoms from the other two tza ligands. The tza ligand bridges two Ag atoms through the carboxylate O atoms and simultaneously binds to the other two Ag atoms through the tetrazole N atoms, forming a two-dimensional network parallel to (100)
Pentaaqua(1H-benzimidazole-5,6-dicarboxylato-κN 3)cobalt(II) pentahydrate
In the title mononuclear complex, [Co(C9H4N2O4)(H2O)5]·5H2O, the CoII atom exhibits a distorted octahedral geometry involving an N atom of a 1H-benzimidazole-5,6-dicarboxylate ligand and five water O atoms. A supramolecular network is generated through intermolecular O—H⋯O hydrogen-bonding interactions involving the coordinated and uncoordinated water molecules and the carboxyl O atoms of the organic ligand. An intermolecular N—H⋯O hydrogen bond is also observed
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