Astronominin büyük veri çağı bu alandaki tüm araştırmacıları kendilerini şanslı hissettirecek kadar bol ve kaliteli veri sağlamaktadır. Gezegen, gökada ve karadelik araştırmaları yıldız astrofiziği ...için hem önemli veriler hem de yeni problemler sunmaktadır. Binlerce kırmızı dev (RG) ve kırmızı budak (RC) yıldızın astrometrik, asterosismik, tayf ve fotometrik hassas verileri kullanılarak temel parametreleri hesaplanabilir. Bu çalışmada, RC yıldızlarının asterosismik ve astrometrik yoldan hesapladığımız kütle ve yarıçaplarını hem birbiriyle hem de önceden hesapladığımız kırmızı devlerin değerleriyle kıyasladık. Bu kıyaslamadan, RG ile RC evreleri arasındaki geçiş sürecinde ortalama 0.1 M⊙ kadar kütle kaybettiği anlaşılıyor. RC yıldızlarının menşei hakkında da çok önemli sonuçlar ortaya çıkıyor. Kütlesi 1.5 M⊙’ten büyük yıldızlarının çok az kısmı RG bölgesinden geçerek bulunduğu konuma ulaşmaktadır.
The big data age of astronomy provides high quality and huge amount of data that makes all researchers in this field feel lucky. Planet, galaxy, and black hole studies present both data and new problems for stellar astrophysics. Fundamental parameters of thousands of red giant (RG) and red clump (RC) stars can be calculated using their precise astrometric, asteroseismic, spectral and photometric data. In this study, we compute and compare the masses and radii of the RC stars, which we calculated from the asteroseismic and astrometric methods. We also compare fundamental properties of RCs with the values of RGs we calculated before. From this comparison, we deduce that an average of 0.1 M⊙ mass is lost during the transition from the RG to the RC phase. There are also very important implications about the origin of RC
stars. Few of the stars with a mass greater than 1.5 M⊙ reach their current location by passing through the RG region.
Abstract
Asteroseismology of bright stars has become increasingly important as a method to determine the fundamental properties (in particular ages) of stars. The Kepler Space Telescope initiated a ...revolution by detecting oscillations in more than 500 main-sequence and subgiant stars. However, most Kepler stars are faint and therefore have limited constraints from independent methods such as long-baseline interferometry. Here we present the discovery of solar-like oscillations in
α
Men A, a naked-eye (
V
= 5.1) G7 dwarf in TESS’s southern continuous viewing zone. Using a combination of astrometry, spectroscopy, and asteroseismology, we precisely characterize the solar analog
α
Men A (
T
eff
= 5569 ± 62 K,
R
⋆
= 0.960 ± 0.016
R
⊙
,
M
⋆
= 0.964 ± 0.045
M
⊙
). To characterize the fully convective M dwarf companion, we derive empirical relations to estimate mass, radius, and temperature given the absolute Gaia magnitude and metallicity, yielding
M
⋆
= 0.169 ± 0.006
M
⊙
,
R
⋆
= 0.19 ± 0.01
R
⊙
, and
T
eff
= 3054 ± 44 K. Our asteroseismic age of 6.2 ± 1.4 (stat) ± 0.6 (sys) Gyr for the primary places
α
Men B within a small population of M dwarfs with precisely measured ages. We combined multiple ground-based spectroscopy surveys to reveal an activity cycle of
P
= 13.1 ± 1.1 yr for
α
Men A, a period similar to that observed in the Sun. We used different gyrochronology models with the asteroseismic age to estimate a rotation period of ∼30 days for the primary. Alpha Men A is now the closest (
d
= 10 pc) solar analog with a precise asteroseismic age from space-based photometry, making it a prime target for next-generation direct-imaging missions searching for true Earth analogs.
We present initial results on some of the properties of open clusters NGC 6791 and NGC 6819 derived from asteroseismic data obtained by NASA's Kepler mission. In addition to estimating the mass, ...radius, and log g of stars on the red giant branch (RGB) of these clusters, we estimate the distance to the clusters and their ages. Our model-independent estimate of the distance modulus of NGC 6791 is (m -- M)0 = 13.11 ? 0.06. We find (m -- M)0 = 11.85 ? 0.05 for NGC 6819. The average mass of stars on the RGB of NGC 6791 is 1.20 ? 0.01 M , while that of NGC 6819 is 1.68 ? 0.03 M . It should be noted that we do not have data that cover the entire RGB and the actual mass will be somewhat lower. We have determined model-dependent estimates of ages of these clusters. We find ages between 6.8 and 8.6 Gyr for NGC 6791, however, most sets of models give ages around 7 Gyr. We obtain ages between 2 and 2.4 Gyr for NGC 6819.
The development of technology and information demands elementary school teachers to be able to make and teach technology-based musical instruments so that the development of technology and ...information can be used in the learning process. Elementary school teachers also have problems teaching musical composition using ensemble musical instruments. Teachers also lack strategies and media to teach musical instruments, so they need to have ideas for developing technology-based musical instruments. This study aims to develop the elementary school teachers’ ability to innovate and make music learning media using a computerized system. The research design used was action research. The participants were 38 teachers from nine regencies and cities in West Java, Indonesia. The results showed that the teachers were able to complete the task of making technology-based learning media which means that they were able to develop their technological abilities to make music learning media. Teachers can easily use and master the Scratch application to make music learning media. It can be concluded that with structured and controlled training, elementary school teachers can develop themselves and innovate well.
Binary stars in which oscillations can be studied in either or both
components can provide powerful constraints on our understanding of stellar
physics. The bright binary 12 Bo\"otis (12 Boo) is a ...particularly promising
system because the primary is roughly 60 per cent brighter than the secondary
despite being only a few per cent more massive. Both stars have substantial
surface convection zones and are therefore, presumably, solar-like oscillators.
We report here the first detection of solar-like oscillations and ellipsoidal
variations in the TESS light curve of 12 Boo. Though the solar-like
oscillations are not clear enough to unambiguously measure individual mode
frequencies, we combine global asteroseismic parameters and a precise fit to
the spectral energy distribution (SED) to provide new constraints on the
properties of the system that are several times more precise than values in the
literature. The SED fit alone provides new effective temperatures, luminosities
and radii of $6115\pm45\,\mathrm{K}$, $7.531\pm0.110\,\mathrm{L}_\odot$ and
$2.450\pm0.045\,\mathrm{R}_\odot$ for 12 Boo A and $6200\pm60\,\mathrm{K}$,
$4.692\pm0.095\,\mathrm{L}_\odot$ and $1.901\pm0.045\,\mathrm{R}_\odot$ for 12
Boo B. When combined with our asteroseismic constraints on 12 Boo A, we obtain
an age of $2.67^{+0.12}_{-0.16}\,\mathrm{Gyr}$, which is consistent with that
of 12 Boo B.
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