Asteroseismology of the Hyades red giant and planet host epsilon Tauri

Asteroseismic analysis of solar-like stars allows us to determine physical parameters such as stellar mass, with a higher precision compared to most other methods. Even in a well-studied cluster such as the Hyades, the masses of the red giant stars are not well known, and previous mass estimates are based on model calculations (isochrones). The four known red giants in the Hyades are assumed to be clump (core-helium-burning) stars based on their positions in colour-magnitude diagrams, however asteroseismology offers an opportunity to test this assumption. Using asteroseismic techniques combined with other methods, we aim to derive physical parameters and the evolutionary stage for the planet hosting star epsilon Tau, which is one of the four red giants located in the Hyades. We analysed time-series data from both ground and space to perform the asteroseismic analysis. By combining high signal-to-noise (S/N) radial-velocity data from the ground-based SONG network with continuous space-based data from the revised Kepler mission K2, we derive and characterize 27 individual oscillation modes for epsilon Tau, along with global oscillation parameters such as the large frequency separation and the ratio between the amplitude of the oscillations measured in radial velocity and intensity as a function of frequency. The latter has been measured previously for only two stars, the Sun and Procyon. Combining the seismic analysis with interferometric and spectroscopic measurements, we derive physical parameters for epsilon Tau, and discuss its evolutionary status.Comment: 13 pages, 13 figures, 4 tables, accepted for publication in Astronomy & Astrophysic

Thermodynamics and Phase Transitions of Dyonic AdS Black Holes in Gauss-Bonnet-Scalar Gravity

In this paper, by treating the cosmological constant as a thermodynamic pressure, we study the thermodynamics and phase transitions of the dyonic AdS black holes in Gauss-Bonnet-Scalar gravity, where the conformal scalar field is considered. In a more general extended phase space, we first verified the first law of black hole thermodynamics, and find that it is always true. Meanwhile, the corresponding Smarr relation is also obtained. Then, we found that this black hole exhibits interesting critical behaviors in six dimensions, i.e., two swallowtails can be observed simultaneously. Interestingly, in a specific parameter space, we observed the small/intermediate/large black hole phase transitions, with the triple point naturally appearing. Additionally, the small/large black hole phase transition, similar to the liquid/gas phase transition of the van der Waals fluids, can also be found in other parameter regions. Moreover, we note that the novel phase structure composed of two separate coexistence curves discovered in the dyonic AdS black holes in Einstein-Born-Infeld gravity disappears in Gauss-Bonnet-Scalar gravity. This suggests that this novel phase structure may be related to gravity theory, and importantly, it is generally observed that the triple point is a universal property of dyonic AdS black holes. On the other hand, we calculated the critical exponents near the critical points and found that they share the same values as in mean field theory. Finally, it is true that these results will provide some deep insights into the interesting thermodynamic properties of the dyonic AdS black holes in the background of conformal scalar fields

SYNTHESIS AND CHARACTERIZATION OF SIDE GROUP-MODIFIED CYCLOTETRAPHOSPHAZENE DERIVATIVES

Two novel cyclotetraphosphazene derivatives were synthesized by the reaction of octachlorocyclotetraphosphazene with the potassium salt of 4-hydroxybenzaldehyde, and subsequent reduction of aldehyde groups to alcohol groups using sodium borohydride. The bromination reaction was carried out using PBr(3) to give N(4)P(4)(OC(6)H(4)-p-CH(2)Br)(8) (4). This compound was employed in reaction with imidazole or morpholine to produce eight-armed, star-branched title compounds. The target compounds were characterized by (1)H, (31)P, and (13)C NMR as well as IR and ESI-MS. The Cu complex of 5a was effective in oxidative cleavage reactions.Natural Science Foundation of China[20972143, 20602032, 20732004, 20972130

Value-added Catalog of M-giant Stars in LAMOST DR9

In this work, we update the catalog of M-giant stars from the low-resolution spectra of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data Release 9. There are 58,076 M giants identified from the classification pipeline with seven temperature subtypes from M0 to M6. The 2471 misclassified non–M-giant stars are white dwarf binaries, early types, and M dwarfs. And the contamination rate is 4.2% in the M-giants sample. A total of 372 carbon stars were identified by CaH spectral indices, and were further confirmed by the LAMOST spectra. We update the correlation between the (W1 – W2) _0 color and [M/H] from APOGEE DR17. We calculate the radial velocities of all M giants by applying cross-correlation to the spectra between 8000 and 8950 Å with synthetic spectra from ATLAS9. Taking star distances less than 4 kpc from Gaia EDR3 as the standard, we refitted the photometric distance relation of M giants. And based on our M-giant stars, we select a group of Sagittarius stream members, whose sky and 3D velocity distributions are well consistent with K-giant Saggitarius stream members found in Yang et al. With our M giants, we find that the disk is asymmetric out to R = 25 kpc, which is 5 kpc further out than detected using K giants

Characterization of photosynthetic electron transport chain in bioenergy crop Jerusalem artichoke (Helianthus tuberosus L.) under heat stress for sustainable cultivation

In order to explore the response of photosynthetic electron transport chain to heat stress, chlorophyll a fluorescence and modulated 820 nm reflection transients were examined in the leaves of Jerusalem artichoke (Helianthus tuberosus L.). J step was elevated at 43 degrees C, suggesting that electron transport beyond primary quinone electron acceptor of photosystem II (Q(A)) was inhibited. I step was elevated at 45 degrees C due to the lowered plastoquinol re-oxidation rate. Significant decrease in the QA reducing reaction centers per photosystem II (PSII) antenna chlorophyll and marked increase in relative variable fluorescence intensity at 300 mu s also occurred at 45 degrees C, indicating that the electron transport chain from PSII donor side to QA was injured. Overall, the fragment between QA and plastoquinol is the most susceptible to heat in the electron transport chain before photosystem I (PSI). The maximal photochemical capacity of PSI was not affected by heat stress even at 48 degrees C, and the interaction between PSII and PSI become unbalanced, when temperature rose to 45 degrees C. At 45 degrees C, prolonged PSI oxidation occurred in the expanding leaves because of the inhibited electron donation from PSII, however, PSI oxidation amplitude decreased in the expanded leaves. We infer that electron transport chain of PSI acceptor side is more sensitive to heat stress than the chain before PSI in the expanded leaves. Therefore, electrons in PSI reaction center could not be efficiently drained to the downstream at high temperature, and then PSI oxidation was blocked. (C) 2013 Elsevier B.V. All rights reserved