Radial velocity is one of the key measurements in understanding the fundamental properties of stars, stellar clusters and the Galaxy. A plate of stars in the Kepler field was observed in May of 2018 with the medium-re...Radial velocity is one of the key measurements in understanding the fundamental properties of stars, stellar clusters and the Galaxy. A plate of stars in the Kepler field was observed in May of 2018 with the medium-resolution spectrographs of LAMOST, aiming to test the performance of this new system which is the upgraded equipment of LAMOST after the first five-year regular survey. We present our analysis on the radial velocity measurements(RVs) derived from these data. The results show that slight and significant systematic errors exist among the RVs obtained from the spectra collected by different spectrographs and exposures, respectively. After correcting the systematic errors with different techniques, the precision of RVs reaches ～1.3,～1.0,～0.5 and ～0.3 km s^(-1) at S/Nr = 10, 20, 50 and 100, respectively. Comparing with the RVs of standard stars from the APOGEE survey, our RVs are calibrated with a zero-point shift of～7 km s^(-1). The results indicate that the LAMOST medium-resolution spectroscopic system may provide RVs with a reasonable accuracy and precision for the selected targets.展开更多
Hydrogen atmosphere pulsating white dwarfs,also known as DAV stars,are the most abundant type of pulsating white dwarfs.High-temperature DAV stars in general exhibit a small number of pulsation modes and stable freque...Hydrogen atmosphere pulsating white dwarfs,also known as DAV stars,are the most abundant type of pulsating white dwarfs.High-temperature DAV stars in general exhibit a small number of pulsation modes and stable frequencies.G132-12 is one of the pulsating hydrogen atmosphere white dwarf stars which lies close to the blue edge of the instability strip.Previous researches reported that G132-12 might have only one pulsation mode with the period of 212.69 s.To study the pulsation properties of G132-12 in detail,we carried out a bi-site observation campaign in October 2019.Time series photometric data were collected during around 154 h in total.A Fourier analysis reveals three frequencies which are identified as the triplet of an l=1 g-mode pulsation with the period of 212.499 s.The rotational period is derived as Prot=35.0±6.7 h and the inclination of the rotational axis to the line of sight is 70°.G132-12 could be an ideal target for measuring the cooling scale of this white dwarf star with only one excited pulsation mode detected.展开更多
基金The Guoshoujing Telescope (the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, LAMOST) is a National Major Scientific Project built by the Chinese Academy of Sciences (CAS)Funding for the project has been provided by the National Development and Reform Commission+3 种基金the support from the National Natural Science Foundation of China (Grant Nos. 11673003 and 11833002)the support from the China Postdoctoral Science Foundation (2018M641244)supported by the Special Funding for Advanced Users, budgeted and administrated by the Center for Astronomical Mega-Science, CASsupported by Key Research Program of Frontier Sciences, CAS (QYZDY-SSW-SLH007)
文摘Radial velocity is one of the key measurements in understanding the fundamental properties of stars, stellar clusters and the Galaxy. A plate of stars in the Kepler field was observed in May of 2018 with the medium-resolution spectrographs of LAMOST, aiming to test the performance of this new system which is the upgraded equipment of LAMOST after the first five-year regular survey. We present our analysis on the radial velocity measurements(RVs) derived from these data. The results show that slight and significant systematic errors exist among the RVs obtained from the spectra collected by different spectrographs and exposures, respectively. After correcting the systematic errors with different techniques, the precision of RVs reaches ～1.3,～1.0,～0.5 and ～0.3 km s^(-1) at S/Nr = 10, 20, 50 and 100, respectively. Comparing with the RVs of standard stars from the APOGEE survey, our RVs are calibrated with a zero-point shift of～7 km s^(-1). The results indicate that the LAMOST medium-resolution spectroscopic system may provide RVs with a reasonable accuracy and precision for the selected targets.
基金support from the National Natural Science Foundation of China(NSFC,Grant Nos.11833002,12090040 and 12090042)financial support of the UNAM(Grant PAPIIT IN100918)。
文摘Hydrogen atmosphere pulsating white dwarfs,also known as DAV stars,are the most abundant type of pulsating white dwarfs.High-temperature DAV stars in general exhibit a small number of pulsation modes and stable frequencies.G132-12 is one of the pulsating hydrogen atmosphere white dwarf stars which lies close to the blue edge of the instability strip.Previous researches reported that G132-12 might have only one pulsation mode with the period of 212.69 s.To study the pulsation properties of G132-12 in detail,we carried out a bi-site observation campaign in October 2019.Time series photometric data were collected during around 154 h in total.A Fourier analysis reveals three frequencies which are identified as the triplet of an l=1 g-mode pulsation with the period of 212.499 s.The rotational period is derived as Prot=35.0±6.7 h and the inclination of the rotational axis to the line of sight is 70°.G132-12 could be an ideal target for measuring the cooling scale of this white dwarf star with only one excited pulsation mode detected.
