نتایج جستجو برای: stellar pulsation

تعداد نتایج: 90649  

2006
G. A. Wade

We have obtained a time series of 81 high-cadence circular polarization observations of the rapidly oscillating Ap star HD 24712 with the new ESPaDOnS spectropolarimeter at CFHT. We used the high-S/N, high-resolution Stokes I and V spectra to investigate possible variation of the mean longitudinal field over the pulsation cycle in this roAp star. Our multiline magnetic field and radial velocity...

2000
Li Zhiping

Five nights photoelectric photometric observations through v and y bands confirm the pulsation of classical Am δ Scuti variable 60 Tau. Power spectrum of light curves shows multi-period pulsation behavior of 60 Tau and two pulsation modes f1=13.0364 and f2=11.8521 cycles per day are definitely identified. Classical Am star 60 Tau is a complicated pulsation δ Scuti variable. Considering the puls...

Journal: :The Astrophysical Journal 2023

Abstract Monitoring of high-resolution spectra in the optical and near-infrared wavelength region was carried out for early post-AGB stage star IRAS Z02229+6208 with CARMENES instrument to reveal spectroscopic variability over pulsation cycle 154 days. Significant changes are seen both intensity position carbon-bearing molecular lines. Strong broad CN red system lines, blueshifted up 9.4 km s −...

2014
Yikai Yuan Jianhua Wu Jingtao Yang Qiang Gao

Gas pulsation in the discharge side of rotary compressor is one of the main sources of noise, so the discharge muffler is widely used to decrease the gas pulsation and noise level. Investigations on pressure pulsation in the muffler can provide not only a method to evaluate the muffler design and modification, but also a base for advanced study of noise in rotary compressor. In this paper the m...

Journal: :Monthly Notices of the Royal Astronomical Society 2022

Pulsation period decrease during the initial stage of thermal pulse in helium-burning shell Mira-type variable T UMi is investigated with numerical methods stellar evolution and radiation hydrodynamics. To this end, a grid evolutionary tracks was calculated for stars masses on main sequence $1M_\odot\le M_\textrm{ZAMS}\le 2.2M_\odot$ metallicity $Z=0.01$. Selected models AGB sequences were used...

1998
S. Frandsen

We present new spectroscopic and photometric time series observations of the δ Scuti star FG Vir. We detect the oscillations via changes in the equivalent widths of hydrogen and metal absorption lines. From the ratios between spectroscopic and photometric amplitudes, we assign l values to the eight strongest oscillation modes. In particular, we identify two radial modes (l = 0) and find that th...

1998
M. M. Hernández F. Pérez Hernández E. Michel

An analysis based on a comparison between observations and stellar models has been carried out to identify radial modes of oscillations in several multi-periodic δ Scuti stars of the Praesepe cluster (BU, BN, BW and BS Cnc). The assumption that all the stars considered have common parameters, such as metallicity, distance or age, is imposed as a constraint. Even so, there is a large number of p...

2000
G. Kovács

We employ the very recent photometric data of the ogle project together with stellar atmosphere and linear pulsation models to determine the distance modulus of the Small Magellanic Cloud from its double-mode Cepheids. Based on the requirement of obtaining the same distance modulus DM from the two types of variables (fundamental & first overtone and first & second overtone), we get DM = 19.05 m...

1999
G. Perrin M. G. Lacasse

The Mira-type star R Leonis was observed at two different epochs in the K band with the FLUOR beam combiner on the IOTA interferometer. A variation of diameter is clearly detected for the very first time at this wavelength revealing an apparent pulsation of atmospheric layers very close to the stellar photosphere. We discuss the excess of visibility measured at high spatial frequencies and show...

2004
MACHO

The lightcurve of the Large Magellanic Cloud (LMC) variable star MACHO 81.8997.87 shows evidence for photometric variations due to both stellar pulsation, with a 2.035 day period, and eclipsing behavior, with an 800.4 day period. The primary star of the system has been identified as a first-overtone Cepheid but the nature of the secondary star has not been determined. Here we present multicolor...

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