The Cepheid Variable S. Sagittae. I. The Radial-Velocity Variation.

1952 ◽  
Vol 116 ◽  
pp. 348 ◽  
Author(s):  
G. H. Herbig ◽  
J. H. Moore
2011 ◽  
Vol 63 (6) ◽  
pp. L67-L71 ◽  
Author(s):  
Norio Narita ◽  
Teruyuki Hirano ◽  
Bun'ei Sato ◽  
Hiroki Harakawa ◽  
Akihiko Fukui ◽  
...  

2020 ◽  
Vol 496 (1) ◽  
pp. L11-L15 ◽  
Author(s):  
R V Baluev ◽  
E N Sokov ◽  
S Hoyer ◽  
C Huitson ◽  
José A R S da Silva ◽  
...  

ABSTRACT We homogeneously reanalyse 124 transit light curves for the WASP-4 b hot Jupiter. This set involved new observations secured in 2019 and nearly all observations mentioned in the literature, including high-accuracy GEMINI/GMOS transmission spectroscopy of 2011–2014 and TESS observations of 2018. The analysis confirmed a non-linear transit timing variation (TTV) trend with $P/|\dot{P}|\sim \hbox{17-30}$ Myr (1σ range), implying only half of the initial decay rate estimation. The trend significance is at least 3.4σ in the aggressively conservative treatment. Possible radial acceleration due to unseen companions is not revealed in Doppler data covering seven years 2007–2014, and radial acceleration of −15 m s−1 yr−1 reported in a recent preprint by another team is not confirmed. If present, it is a very non-linear radial velocity variation. Assuming that the entire TTV is tidal in nature, the tidal quality factor $Q_\star ^{\prime }\sim \hbox{(4.5-8.5)}\times 10^4$ does not reveal a convincing disagreement with available theory predictions.


2000 ◽  
Vol 176 ◽  
pp. 248-249
Author(s):  
László Szabados

AbstractTwo parameters are defined involving the observed (peak-to-peak) amplitudes in U, B, V, and R photometric bands as well as that of the radial velocity variation. They are used to detect companions to Cepheids for a sample about 300 Galactic Cepheids.


1988 ◽  
Vol 126 ◽  
pp. 675-676
Author(s):  
Robert D. Mathieu ◽  
David W. Latham

Mathieu et al. (1986) have completed an extensive radial-velocity survey of over 100 late-type stars in M 67 with V < 12.8. The spatial distributions of the spectroscopic binaries and single stars (i.e. those stars without detected radial-velocity variation; many of these are undoubtedly binaries, albeit with lower secondary masses) are shown in Fig. 1. The distribution of the binaries is notably more centrally concentrated than the single stars. The two observed distributions derive from distinct parent distributions at the 98% confidence level. The projected half-mass radius of the binaries is 0.9 pc; the half-mass radius of the single stars is 2.4 pc. Indeed, 77% of the binaries lie within the single-star half-mass radius.


2021 ◽  
Vol 57 (1) ◽  
pp. 39-55
Author(s):  
E. Yoldaş ◽  
H. A. Dal

We present findings about the nature of KOI-258. Its temperature was found to be 6500 ± 200 K from its spectrum, which also indicates that the target is a single main sequence star despite the existence of a radial velocity variation with a small amplitude. Ca II H, K lines indicate the existence of magnetic activity, though there is no remarkable excess or variation in the Hα line. We found 51 flares with a frequency of 0.00186 h−1, whose plateau value is 0.659 s. Apart from the flares, we found 420 frequencies due to solar-like oscillations at out-of-eclipses. Removing these 420 frequencies, we demonstrated three different transits caused by three exo-planets. Their radii were found to be 2.33 R_&oplus; for the first planet, 0.53 R_&oplus; for the second one, and 1.15 R_&oplus; for the third planet. Consequently, KOI-258 is an oscillating, single, main sequence star, with in a planetary system and remarkable flare activity.


1975 ◽  
Vol 87 ◽  
pp. 259 ◽  
Author(s):  
C. T. Bolton ◽  
G. Wicks ◽  
R. B. Jones ◽  
A. Young

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