scholarly journals CubeSpec space mission. I. Asteroseismology of massive stars from time series optical spectroscopy: science requirements and target list prioritisation

2021 ◽  
Author(s):  
D. M. Bowman ◽  
B. Vandenbussche ◽  
H. Sana ◽  
A. Tkachenko ◽  
G. Raskin ◽  
...  
Keyword(s):  
Time Series ◽  
Optical Spectroscopy ◽  
Massive Stars ◽  
Space Mission ◽  
Target List

scholarly journals Asteroseismology of OB stars with hundreds of single snapshot spectra (and a few time-series of selected targets)

2014 ◽  
Vol 9 (S307) ◽  
pp. 194-199 ◽  
Author(s):  
S. Simón-Díaz
Keyword(s):  
Time Series ◽  
Massive Stars ◽  
Ob Stars ◽  
Stellar Oscillations ◽  
Large Samples ◽  
Single Snapshot

AbstractImagine we could do asteroseismology of large samples of OB-type stars by using just one spectrum per target. That would be great! But this is probably a crazy and stupid idea. Or maybe not. Maybe we have the possibility to open a new window to investigate stellar oscillations in massive stars that has been in front of us for many years, but has not attracted very much our attention: the characterization and understanding of the so-called macroturbulent broadening in OB-type stars.

scholarly journals New observations of NGC 1624-2 reveal a complex magnetospheric structure and underlying surface magnetic geometry*

2020 ◽  
Author(s):  
A David-Uraz ◽  
V Petit ◽  
M E Shultz ◽  
A W Fullerton ◽  
C Erba ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Time Series ◽  
Magnetic Fields ◽  
Hubble Space Telescope ◽  
Massive Stars ◽  
Complex Structure ◽  
Type Star ◽  
Origin And Evolution ◽  
Field Geometry

Abstract NGC 1624-2 is the most strongly magnetized O-type star known. Previous spectroscopic observations of this object in the ultraviolet provided evidence that it hosts a large and dense circumstellar magnetosphere. Follow-up observations obtained with the Hubble Space Telescope not only confirm that previous inference, but also suggest that NGC 1624-2’s magnetosphere has a complex structure. Furthermore, an expanded spectropolarimetric time series shows a potential departure from a dipolar magnetic field geometry, which could mean that the strongest field detected at the surface of an O-type star is also topologically complex. This result raises important questions regarding the origin and evolution of magnetic fields in massive stars.

scholarly journals Predictions on the Number of Variable Stars for the GAIA Space Mission and for Surveys such as the Ground-Based International Liquid Mirror Telescope

2000 ◽  
Vol 176 ◽  
pp. 71-72 ◽  
Author(s):  
Laurent Eyer ◽  
Jan Cuypers
Keyword(s):  
Time Series ◽  
Space Mission ◽  
Variable Stars ◽  
Photometric Data ◽  
Huge Number ◽  
Future Space ◽  
Survey Instruments ◽  
Mirror Telescope ◽  
Stars Survey

AbstractFuture space and ground-based survey programmes will produce an impressive amount of photometric data. The GAIA space mission will map the complete sky down to V = 20m, and produce time series for about 1 billion stars. Survey instruments such as the International Liquid Mirror Telescope will observe slices of the sky down to V = 23m. In both experiments, the opportunity exists to discover a huge number of variable stars. Predictions of the expected total number of variable stars and the number of variables in specific subgroups are given.

scholarly journals TESS’s first planet

2018 ◽  
Vol 619 ◽  
pp. L10 ◽  
Author(s):  
D. Gandolfi ◽  
O. Barragán ◽  
J. H. Livingston ◽  
M. Fridlund ◽  
A. B. Justesen ◽  
...  
Keyword(s):  
Time Series ◽  
Orbital Period ◽  
Space Mission ◽  
Planetary Atmosphere ◽  
Mass Determination ◽  
Naked Eye ◽  
Wide Range ◽  
Dynamical Properties ◽  
Marginal Detection

We report on the confirmation and mass determination of π Men c, the first transiting planet discovered by NASA’s TESS space mission. π Men is a naked-eye (V = 5.65 mag), quiet G0 V star that was previously known to host a sub-stellar companion (π Men b) on a longperiod (Porb = 2091 days), eccentric (e = 0.64) orbit. Using TESS time-series photometry, combined with Gaia data, published UCLES at AAT Doppler measurements, and archival HARPS at ESO-3.6m radial velocities, we found that π Men c is a close-in planet with an orbital period of Porb = 6.27 days, a mass of Mc = 4.52 ± 0.81 M⊕, and a radius of Rc = 2.06 ± 0.03 R⊕. Based on the planet’s orbital period and size, π Men c is a super-Earth located at, or close to, the radius gap, while its mass and bulk density suggest it may have held on to a significant atmosphere. Because of the brightness of the host star, this system is highly suitable for a wide range of further studies to characterize the planetary atmosphere and dynamical properties. We also performed an asteroseismic analysis of the TESS data and detected a hint of power excess consistent with the seismic values expected for this star, although this result depends on the photometric aperture used to extract the light curve. This marginal detection is expected from pre-launch simulations hinting at the asteroseismic potential of the TESS mission for longer, multi-sector observations and/or for more evolved bright stars.

The LDE-Type Flare Occurrence (1969-1993)

1994 ◽  
Vol 144 ◽  
pp. 279-282
Author(s):  
A. Antalová
Keyword(s):  
Time Series ◽  
Fourier Analysis ◽  
Sunspot Cycle ◽  
List Type ◽  
Type Number ◽  
Solar Cycles ◽  
Type Iv ◽  
Long Duration ◽  
Cycle Maximum ◽  
Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

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