The Chinese Space Station Survey Telescope (CSST) is an upcoming Stage-IV sky survey telescope, distinguished by its large field of view (FoV), high image quality, and multi-band observation capabilities. It can simultaneously conduct precise measurements of the Universe by performing multi-color photometric imaging and slitless spectroscopic surveys. The CSST is equipped with five scientific instruments, i.e., Multi-band Imaging and Slitless Spectroscopy Survey Camera (SC), Multi-Channel Imager (MCI), Integral Field Spectrograph (IFS), Cool Planet Imaging Coronagraph (CPI-C), and THz Spectrometer (TS). Using these instruments, CSST is expected to make significant contributions and discoveries across various astronomical fields, including cosmology, galaxies and active galactic nuclei (AGN), the Milky Way and nearby galaxies, stars, exoplanets, Solar System objects, astrometry, and transients and variable sources. This review aims to provide a comprehensive overview of the CSST instruments, observational capabilities, data products, and scientific potential.

The frequency of the pressure (p) mode in δ Scuti stars can exceed the Nyquist limit of Kepler long-cadence photometry. These “superNyquist frequencies” (SNFs) are observed as “reflected” peaks at lower frequencies, i.e., they are Nyquist aliases that pose a threat to asteroseismic diagnostics. Their impact on δ Scuti p modes has yet to be comprehensively explored. We performed a systematic survey to search for SNFs in 1838 Kepler δ Scuti stars through a novel technique based on a sliding Lomb-Scargle periodogram, identifying 15 265 confirmed SNFs in 1309 stars, from a total of 259 883 frequencies. We observe that the total number of detected frequencies per star remains featureless across the δ Scuti instability strip; however, young stars pulsate in higher frequencies and so have significantly more SNFs on average. Both the number and the rate of SNFs diminish accordingly as δ Scuti stars become more evolved, which is consistent with both observation and stellar models. Furthermore, our method detects a greater fraction of modes as SNFs at higher frequencies, rising from approximately 1% at 20 μHz to 23% at the Nyquist limit. The rate of underdetection is highest amongst low-amplitude modes. The SNF modulation patterns can be well distinguished from phase modulations induced by binarity or nonlinear mode interactions. We provide a frequency catalog for future asteroseismic studies of δ Scuti stars, wherein we identify each peak as being real or an alias, enabling further investigations into regular patterns of pulsation modes, linear combination frequencies, and theoretical modeling.

Context. The extent of envelope stripping in progenitor stars is directly reflected in the diversity of spectral features that are observed in stripped-envelope supernovae (SESNe). Aims. Through extensive spectral observation and analysis, we aim to clarify the statistical differences between the subclasses of SESNe. Methods. The Tsinghua supernova group obtained 249 optical spectra of 62 SESNe from 2010 to 2020, covering phases from –16 to over 190 days relative to maximum light. Most spectra were obtained during the photospheric phases after the supernova explosion. For each spectrum, the pseudo-equivalent widths and blueshift velocities of the principal lines were measured. We further investigated the common spectral features by analyzing their velocity and strength correlations across all subtypes. Results. We identified the feature near 6200 Å in SNe Ib as Hα through a comparison with SNe IIb and Ic. This resolves inconsistent interpretations in the literature. Our finding reveals prevalent residual hydrogen in SNe Ib, further supporting a continuous stripping sequence from SNe IIb to Ib. The velocity among different subtypes of stripped-envelope SNe increases, with SNe IIb exhibiting the lowest line velocities, followed by Ib, Ic, and Ic-BL. Typically, the O I lines in SNe Ic/Ic-BL are stronger than those seen in SNe IIb/Ib. In nebular phases, the [Ca II] emission dominates [O I] in SNe IIb/Ib, while [O I] is stronger in SNe Ic, including in the He-rich SN 2016coi. This spectral dichotomy implies that progenitors of SNe Ic (BL) have more massive CO cores and hence higher initial masses.

Asteroseismology of member pulsators provides a robust physical constraint on cluster parameters by linking internal stellar structures to the global properties of the host cluster. However, the parameters of NGC 1647 remain poorly constrained due to limited investigation, a situation that cluster asteroseismology can significantly refine. In this study, we identified 271 high-confidential cluster members in NGC 1647, using Hierarchical Density-Based Spatial Clustering of Applications with Noise clustering with radial-velocity validation. Its initial age is determined in the range of similar to 125-280 Myr, derived from isochrone fitting based on multisurvey metallicities (LAMOST, APOGEE, and NOT) and extinction-corrected Gaia photometry. Among the members, we found 96 periodic variables from TESS and K2 photometry, including nine p-mode pulsators (five delta Sct and four hybrid delta Sct-gamma Dor stars). Assuming a common cluster age and initial chemical composition, joint asteroseismic modeling is performed based on measured large frequency separations and individual mode frequencies. This yields a metallicity of [Fe/H]=-0.08-0.01+0.04 , consistent with the spectroscopic determinations, and a seismic age of 178-9+11 Myr, more precise than isochrone-based estimates. This work shows the diagnostic potential of delta Sct asteroseismology in young open clusters and establishes a high-precision benchmark for future studies of NGC 1647 and other open clusters.

The quest for the origin of linear combination frequencies in pulsating stars is critical for mode identification and subsequent seismic modeling. Hybrid γ Doradus (Dor) stars provide a crucial testbed for such investigations due to their rich frequency content in both gravity (g) and pressure (p) modes. Here, we performed a comprehensive survey of 608 Kepler γ Dor stars, detecting 81,265 frequencies, and identifying 1,895 harmonics and 45,968 combinations involving two parent frequencies. Our results suggest that the proportion of linear combinations increases with the frequency number in each γ Dor star, leveling off at approximately 75

Theoretical investigations predict a minimum mass ratio of about 0.085–0.095 for contact binaries. If the mass ratio is below the critical value, a tidal instability occurs, forcing the stars to merge into a single object. Observationally, however, more and more W UMa-type binaries have been found to have mass ratios lower than the theoretical limit. In this study, we try to solve this discrepancy by considering the stellar structure and evolution probed through asteroseismology. We searched for and detected gravity ( g )- and Rossby ( r )-mode pulsations in four contact binaries with mass ratios less than 0.1. A seismic study of the pulsations led us to identify the pulsation modes and determine the near-core and envelope rotation rates as well as the asymptotic period spacings of the pulsating, primary stars. By asteroseismic modeling, the stellar parameters were constrained, and the structure models were constructed. This enables us to determine the gyration radii of the primaries and investigate in detail the orbital stability of the contact systems. We indicate that both the mass and age have independent effects on orbital stability, with massive and older primaries being more stable. Moreover, differential core-to-surface rotation would significantly reduce the gyration radius and hence the minimum mass ratio of a contact system. Adopting the median value of the gyration radius derived for the four stars, we estimate a critical mass ratio of 0.042–0.044, depending on the filling factor.

The frequency of pressure (p) mode in δ Scuti stars can exceed the Nyquist limit of Kepler long-cadence photometry. These 'super-Nyquist frequencies' (SNFs) are observed as 'reflected' peaks at lower frequencies, i.e., they are Nyquist aliases that pose a threat to asteroseismic diagnostics. Their impact on δ Scuti p modes has yet to be comprehensively explored. We performed a systematic survey to search for SNFs in 1,838 Kepler δ Scuti stars through a novel technique based on sliding Lomb-Scargle periodogram, identifying 15,265 confirmed SNFs in 1,309 stars, from a total of 259,883 frequencies. We observe that the total number of detected frequencies per star remains featureless across the δ Scuti instability strip; however, young stars pulsate in higher frequencies and so have significantly more SNFs on average. Both the number and the rate of SNFs diminishes accordingly as δ Scuti stars become more evolved, which is consistent with both observation and stellar models. Furthermore, our method detects a greater fraction of modes as SNFs at higher frequencies, rising from approximately 1% at 20 μHz to 23% at the Nyquist limit. The rate of underdetection is highest amongst low-amplitude modes. The SNF modulation patterns can be well distinguished from phase modulations induced by binarity or nonlinear mode interactions. We provide a frequency catalog for future asteroseismic studies of δ Scuti stars, wherein we identify each peak as being real or an alias, enabling further investigations into regular patterns of pulsation modes, linear combination frequencies, and theoretical modeling.

The high-precision and long-duration photometry provided by the Kepler mission has greatly advanced frequency analyses of a large number of pulsating stars, a fundamental step in asteroseismology. For δ Scuti stars, analyses are typically confined to frequencies below the Nyquist frequency. However, signals above this limit can be reflected into the sub-Nyquist range, especially in long-cadence data, where they may overlap with genuine pulsation modes and lead to misinterpretation. To address this issue, a recently proposed method—the sliding Lomb–Scargle periodogram (sLSP)—can effectively distinguish real frequencies from aliased ones. In this study, we compiled a sample of 68 δ Scuti stars whose frequency analyses were based on the Kepler photometry. Using the sLSP method, we systematically examined the 1406 reported frequencies in the literature. As a result, we identified six previously unrecognized reflected super-Nyquist frequencies in four stars: KIC 3440495, KIC 5709664, KIC 7368103, and KIC 9204718. We have once again demonstrated the ability of the sLSP method to detect and correct such artifacts. This technique improves the reliability of frequency selection, thereby enhancing the accuracy of asteroseismic interpretation and stellar modeling for pulsating stars.

A subclass of intermediate mass variables Delta Scuti stars, known as High-amplitude Delta Scuti (HADS) stars, exhibits pronounced radial pulsations with high amplitudes. The ground-based and space-based observations of the HADS star EH Lib are used to help making asteroseismological analysis of this pulsating star. Following the reduction of the light curves, the frequency analysis reveals the fundamental frequency as f_0=11.3105 c day^-1 and two more significant frequencies f_1 and f_2, in addition to the harmonics of f_0 and a linear combination. The period change rate is determined as (1/P_0)(dP_0/dt)=(5.4±0.5)×10^-9 yr^-1 derived from an O-C diagram, which is constructed from 342 times of maximum light spanning over 70 years. Using these observational constraints, along with the metallicity reported in the literature, we construct theoretical models using the stellar evolution code MESA and calculate the theoretical frequencies of the eigen modes using the oscillation code GYRE. The appropriate models are selected by matching both f_0 and (1/P_0)(dP_0/dt) within their respective uncertainties. The results indicate that the observed period change of EH Lib can be attributed to stellar evolutionary effects. The stellar parameters of EH Lib are derived as: the mass of 1.715±0.065 M_⊙, the luminosity of log (L/L_⊙)=1.38±0.06, and the age of (1.14±0.13)×10^9 years. EH Lib is classified as a single-mode HADS star, locating currently in the Hertzsprung gap, with a helium core and a hydrogen-burning shell. This work expands the asteroseismological sample of HADS stars and establishes a foundation for future investigations into their commonalities and specific properties, thereby advancing our understanding of these variables.

In this study, we conduct a comparative analysis of the properties of Blazhko and non-Blazhko RRab stars. We identified 1054 non-Blazhko and 785 Blazhko RRab stars in the photometric data observed by the K2 mission, which, combined with those 37 stars observed in the original Kepler field, constituted our study sample. Using the Fourier decomposition method, we calculated the pulsation parameters, including phase differences and amplitude ratios, for these RRab stars, revealing significant discrepancies in the pulsation parameters between Blazhko and non-Blazhko RRab stars. However, distinguishing between Blazhko and non-Blazhko RRab stars based on Fourier parameters remains challenging due to the significant overlap in their distributions. By crossmatching our sample with the low-resolution spectra of LAMOST Data Release (DR) 12, we identified 147 Blazhko and 111 non-Blazhko RRab stars, which exhibit similar metallicity distributions. Furthermore, crossmatching with Gaia DR3 data yielded 766 Blazhko and 950 non-Blazhko RRab stars, showing differences in color indices but not in absolute magnitudes. Our findings suggest that the Blazhko effect is linked to pulsation parameters and colors rather than metallicities or absolute magnitude.

Young, solar-like stars in the pre-main-sequence (PMS) stage exhibit vigorous magnetic activity that significantly influences their circumstellar environments and the processes of planetary formation and evolution. In binary systems, tidal forces and magnetic interactions can further shape the magnetic geometry. We report a longitudinal preference of starspots, chromospheric activities, and flares in the active single-lined spectroscopic PMS binary system V2279 Cyg, based on long-term photometric observations from Kepler and TESS alongside spectroscopic data from LAMOST. The system is classified as a weak-line T Tauri binary, with component masses estimated at 0.86 M _⊙ and 0.27 M _⊙ . V2279 Cyg’s nearly circular orbit is synchronized with its 4.126 day rotational period. Observations reveal large starspot regions clustered near the far-side hemisphere. Spectroscopic data show strong, double-peak H α emission, the strength of which is highly correlated with starspot distribution, indicating the presence of an active longitude on the primary star. We also mapped the prominence structure corotating with the primary star, suggesting a dense structure close to the near-side hemisphere. Furthermore, we identify an inactive longitude of flares during the 4 yr Kepler observations, where the frequency of flare activity is significantly reduced after the superior conjunction, marking the first such identification in active binary systems. Additionally, a white light superflare, releasing energy of 2.5 × 10 ^37 erg, was detected in TESS observations. These findings provide valuable insights into the magnetic field geometry and dynamo processes in PMS binaries, underscoring the critical role of tidal interactions in shaping magnetic activities.

Magnetic fields in the upper atmospheres of solar-like stars are believed to provide an enormous amount of energy to power the hot coronae and drive large-scale eruptions that could impact the habitability of planetary systems around these stars. However, these magnetic fields have never been routinely measured on stars beyond the solar system. Through decade-long spectropolarimetric observations, we have now achieved the measurements of magnetic fields in the lower and middle chromospheres of three M-dwarfs. Our results indicate that the line-of-sight component of the chromospheric magnetic fields can reach up to hundreds of Gauss, whose sign frequently opposes that of the photospheric field. The measurements highlight the magnetic field complexity and the variation with height close to the surface of these M-dwarfs. They provide critical constraints on the energy budget responsible for heating and eruptions of stellar upper atmospheres, and enable assessments of how stellar magnetic activity may affect exoplanet environments.

The pulsation of white dwarfs provides crucial information on stellar parameters for understanding the atmosphere and interior structure of these stars. In this study, we present a comprehensive statistical analysis of known ZZ Ceti stars from historical literature. Our dataset includes stellar parameters and oscillation properties from 339 samples, with 194 of them having undergone asteroseismological analysis. We investigated the empirical instability strip of ZZ Ceti stars and confirmed the linear relationship between temperature and weighted mean pulsation periods (WMP). We found that the WMP distribution is well-described with two groups of stars with peak values at ∼254 and ∼719 s. Using seismic mass and trigonometrical radii derived from GAIA DR3 parallaxes, we tested the mass-radius relationship of white dwarfs through observational and seismic analysis of ZZ Cetis. They are generally larger than the theoretical values, with the discrepancy reaching up to ∼15

Located at Dome A, the highest point on the Antarctic plateau, China’s Kunlun station is a premier ground-based photometric observatory. Its cold, dry, and stable atmosphere allows continuous observation for over 40 days during polar winter, ideal for detecting short-period transiting exoplanets. Since 2008, the Antarctic Survey Telescopes (AST3) project has pursued the CHESPA program to search for exoplanet candidates. During the austral winters in 2016 and 2017, the AST3-II telescope surveyed fields located in the southern continuous viewing zone of the Transiting Exoplanet Survey Satellite (TESS). This paper presents the second data release from CHESPA, encompassing photometric data for over 85,000 bright ( m _i ≤ 15) stars. The survey achieved a photometric precision of approximately 2 mmag at optimal brightness levels. To illustrate the data quality, we present a catalog of 203 newly identified variable stars showing brightness variations over 5 mmag based on the 2017 observations, as compared to Data Release 1. Among these, 26 are newly recognized periodic variables that are not listed in the AAVSO database ( https://www.aavso.org/ ), and 86 are in the TESS Candidate Target List. These variables required rigorous examination to eliminate false-positive signals in the transiting exoplanets search.

The LAMOST-Kepler/K2 Medium-Resolution Spectroscopic Survey (LK-MRS) conducted time-domain (TD) medium-resolution spectroscopic observations of 20 LAMOST plates in the Kepler and K2 fields from 2018 to 2023, a phase designated as LK-MRS-I. A catalog of stellar parameters for a total of 36,588 stars, derived from the spectra collected during these 5 yr, including the effective temperature, the surface gravity, the metallicity, the alpha-element abundance, the radial velocity (RV), and vsini of the target stars, is released, together with the weighted averages and uncertainties. At a signal-to-noise ratio = 10, the measurement uncertainties are 120 K, 0.18 dex, 0.13 dex, 0.08 dex, 1.9 km s-1, and 4.0 km s-1 for the above parameters, respectively. Comparisons with the parameters provided by the APOGEE and GALAH surveys validate the effective temperature and surface gravity measurements, showing minor discrepancies in metallicity and alpha-element abundance values. We identified some peculiar star candidates, including 764 metal-poor stars, 174 very metal-poor stars, and 30 high-velocity stars. Moreover, we found 2333 stars whose RV seems to be variable. Using Kepler/K2 or TESS photometric data, we confirmed 371 periodic variable stars among the RV variable candidates and classified their variability types. LK-MRS-I provides spectroscopic data that is useful for studies of the Kepler and K2 fields. The LK-MRS project will continue collecting TD medium-resolution spectra for target stars during the third phase of LAMOST surveys, providing data to support further scientific research.

The radius inflation is predominantly observed in short-period, low-mass stellar systems, while being rarely detected in long-period binaries. Using Transiting Exoplanet Survey Satellite photometric and Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic survey data, we conducted a detailed photometric and spectroscopic analysis of six long-period (P > 7 days) detached eclipsing binaries: TIC 17303250, TIC 196817076, TIC 219488423, TIC 252991035, TIC 344753509, and TIC 72696540. Our results indicate that the first five systems are composed of low-mass stars (M <= 0.8M(circle dot)), while TIC 72696540 is likely composed of subgiant stars with M-1 = 1.267 +/- 0.011M(circle dot), R-1 = 2.365 +/- 0.043R(circle dot), and M-2 = 1.281 +/- 0.011M(circle dot), R-2 = 2.517 +/- 0.035R(circle dot). Their large radii are solely due to their evolutionary stage. Apart from TIC 72696540, none of the components of these systems displays a clear Li I lambda 6708 line. Under the assumption of binary rotational synchronization, the rotational velocities of these low-mass stars are found to be less than 8 km s(-1), which is the upper limit related to the LAMOST-MRS resolution. Notably, however, significant radius inflation is evident in the systems TIC 17303250, TIC 344753509, and TIC 252991035. Their radii exceed the predictions of the 12 Gyr isochrones. A positive correlation between radius inflation and metallicity is evident in four of the five low-mass stars, with TIC 196817076 being the sole exception. These results suggest that metallicity may play a significant role in causing radius inflation.

Utilizing data from the Transiting Exoplanet Survey Satellite (TESS) and LAMOST, we present a photometric and spectroscopic investigation of two new K-type low-mass eclipsing binaries, TIC 56913729 and TIC 97729372. Our analysis yields masses and radii for TIC 56913729, M 1 = 0.7822 +/- 0.0054M circle dot, R 1 = 0.7891 +/- 0.0021R circle dot, and M 2 = 0.7532 +/- 0.0052M circle dot, R 2 = 0.7648 +/- 0.0021R circle dot. For TIC 97729372, the results are M 1 = 0.6410 +/- 0.0058M circle dot, R 1 = 0.6537 +/- 0.0069R circle dot and M 2 = 0.6480 +/- 0.0058M circle dot, R 2 = 0.6418 +/- 0.0062R circle dot. In addition, by analyzing the out-of-eclipse starspot light variations, the lower limit of starspot coverage varies in different TESS sectors from 2% to 12%. We observed a clear radius inflation in the mass-radius diagram for both stars, when plotted against PARSEC and SPOT isochrones with 1 Gyr. Yet, this apparent discrepancy disappears when the comparison is made with either an older PARSEC isochrone (12 Gyr) or a SPOT isochrone (250 Myr) with high starspot coverage (F spot similar to 85%), which is significantly higher than the typical starspot coverage deduced from light curves. Due to the lack of strong age constraints, we cannot firmly exclude that the observed radius inflation may be the result of a post-main-sequence evolutionary effect, although the spectral and kinematic properties of these stars are hardly compatible with 10-12 Myr old (Pop II) stars. It is more likely that the radius inflation is produced by the strong magnetic activity in these rapidly rotating stars, even if it is impossible to infer the actual total spot coverage, due to the age uncertainties.

KIC 6362386 is an eclipsing binary system that exhibits both gamma Doradus (gamma Dor)-type pulsations and starspots. In this study, we investigated this binary system using the Kepler photometry and the spectroscopic data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. After employing the PHOEBE program for light-curve and radial-velocity-curve synthesis, analyses reveal that the binary is a circle (e similar to 0.0006), has a small mass ratio (q similar to 0.311), and is a detached system consisting of an F-type primary star and an M-type secondary star with masses and radii of M 1 = 1.43 +/- 0.13 M circle dot, R 1 = 1.68 +/- 0.08 R circle dot and M 2 = 0.44 +/- 0.18 M circle dot, R 2 = 0.46 +/- 0.06 R circle dot, respectively. Utilizing the Padova isochrone, we estimate the age of the binary system to be 1.58-0.13+0.15 Gyr. By analyzing the out-of-eclipse residuals, we identify variations in the residuals attributed to both starspots and stellar pulsations. The autocorrelation function analysis indicates the decay time of starspots is approximately 37 days with the rotation period aligning with the orbital period. Considering the masses, radii, and positions of the two components on the Hertzsprung-Russell diagram, we deduce that the gamma Dor-type g-mode pulsations came from the primary star where the main frequency is 0.1642c/d. Consequently, KIC 6362386 becomes a valuable target for the investigation of gamma Dor-type pulsations and asteroseismology in a binary system.

Context. KIC 10685175 is a roAp star whose polar magnetic field is predicted to be 6 kG through a nonadiabatic axisymmetric pulsation theoretical model. Aims. In this work, we aim to measure the magnetic field strength of KIC 10685175 using high-resolution spectropolarimetric observations, and compare it with the one predicted by the theoretical model. Methods. Two high-resolution unpolarized spectra have been analyzed to ascertain the presence of magnetically split lines and derive the iron abundance of this star through equivalent width measurements of 10 Fe lines. One polarized spectrum has been used to measure the mean longitudinal magnetic field with the least-squares deconvolution technique. Further, to examine the presence of chemical spots on the stellar surface, we have measured the mean longitudinal magnetic fields using different lines belonging to different elements. Results. From the study of two high-resolution unpolarized spectra, we obtained the spectroscopic atmospheric parameters including the effective temperature (Teff), surface gravity (log g), iron abundance ([Fe/H]), abundance ratio of alpha elements to iron ([alpha/Fe]), and micro-turbulent velocity (Vmic). The final result is [T-eff, log g, [Fe/H], [alpha/Fe], V-mic)]=[8250 +/- 200 K, 4.4 +/- 0.1, -0.4 +/- 0.2, 0.16 +/- 0.1, 1.73 +/- 0.2 km s(-1)]. Although the Fe absorption lines appear relatively weak in comparison to typical Ap stars with similar Teff, the lines belonging to rare earth elements (Eu and Nd) are stronger than those in chemically normal stars, indicating the peculiar nature of KIC 10685175. The mean longitudinal magnetic field, < Bl > = -226 +/- 39 G, was measured in the polarized spectrum, but magnetically split lines were not detected. No significant line profile variability is evident in our spectra. Also, the longitudinal magnetic field strengths measured using line masks constructed for different elements are rather similar. Due to the poor rotation phase coverage of our data, additional spectroscopic and polarimetric observations are needed to allow us to come to any conclusions about the inhomogeneous element distribution over the stellar surface. Conclusions. The estimated polar magnetic field is 4.8 +/- 0.8 kG, which is consistent with the predicted polar magnetic field strength of about 6kG within 3 sigma. This work therefore provides support for the pulsation theoretical model.

We present a comprehensive analysis of oscillations of the helium-rich white dwarf DBV star EPIC 248705247 (SDSS J102106.69+082724.8). We extract the light curves from 79.7 days of K2 Campaign 14 data and identify 21 independent frequencies, including three complete and three incomplete dipole modes, with an average frequency splitting of 20.37 +/- 0.40 mu Hz. Our analyses reveal a rotation period of EPIC 248705247 of approximately 6.82 +/- 0.07 hr, making it one of the most rapidly rotating DBV stars currently known. We utilize the White Dwarf Evolution Code (WDEC) to compute models to look for the seismic best-fitted model, yielding the following stellar parameters: M/M circle dot = 0.650 +/- 0.003, T eff = 23,660 +/- 68 K, log(Menv/M*)=-2.01 +/- 0.01 and log(MHe/M*)=-4.90 +/- 0.05 . We also explore the phenomenon of mode trapping, as well as the potential influence of a weak magnetic field. We find that this star is located near the red edge of the theoretical instability strip of DBVs. Hence, our asteroseismological analysis of EPIC 248705247 provides the properties and behaviors of a rapidly rotating DBV.