scholarly journals Line-depth-ratio temperatures for the close binary ν Octantis: new evidence supporting the conjectured circumstellar retrograde planet

2015 ◽  
Vol 449 (4) ◽  
pp. 4428-4442 ◽  
Author(s):  
D. J. Ramm
Keyword(s):  
Close Binary ◽  
Depth Ratio ◽  
New Evidence ◽  
Line Depth

scholarly journals HDO and SO2 thermal mapping on Venus

2020 ◽  
Vol 639 ◽  
pp. A69 ◽  
Author(s):  
T. Encrenaz ◽  
T. K. Greathouse ◽  
E. Marcq ◽  
H. Sagawa ◽  
T. Widemann ◽  
...  
Keyword(s):  
Local Time ◽  
Mixing Ratio ◽  
Echelle Spectrograph ◽  
Imaging Spectrometer ◽  
Infrared Telescope ◽  
Depth Ratio ◽  
Time Period ◽  
Telescope Facility ◽  
Line Depth

Since January 2012, we have been monitoring the behavior of sulfur dioxide and water on Venus, using the Texas Echelon Cross-Echelle Spectrograph imaging spectrometer at the NASA InfraRed Telescope Facility (IRTF, Mauna Kea Observatory). Here, we present new data recorded in February and April 2019 in the 1345 cm−1 (7.4 μm) spectral range, where SO2, CO2, and HDO (used as a proxy for H2O) transitions were observed. The cloud top of Venus was probed at an altitude of about 64 km. As in our previous studies, the volume mixing ratio (vmr) of SO2 was estimated using the SO2/CO2 line depth ratio of weak transitions; the H2O volume mixing ratio was derived from the HDO/CO2 line depth ratio, assuming a D/H ratio of 200 times the Vienna standard mean ocean water. As reported in our previous analyses, the SO2 mixing ratio shows strong variations with time and also over the disk, showing evidence for the formation of SO2 plumes with a lifetime of a few hours; in contrast, the H2O abundance is remarkably uniform over the disk and shows moderate variations as a function of time. We have used the 2019 data in addition to our previous dataset to study the long-term variations of SO2 and H2O. The data reveal a long-term anti-correlation with a correlation coefficient of −0.80; this coefficient becomes −0.90 if the analysis is restricted to the 2014–2019 time period. The statistical analysis of the SO2 plumes as a function of local time confirms our previous result with a minimum around 10:00 and two maxima near the terminators. The dependence of the SO2 vmr with respect to local time shows a higher abundance at the evening terminator with respect to the morning. The dependence of the SO2 vmr with respect to longitude exhibits a broad maximum at 120–200° east longitudes, near the region of Aphrodite Terra. However, this trend has not been observed by other measurements and has yet to be confirmed.

scholarly journals Effective temperature vs. line-depth ratio for ELODIE spectra: Gravity and rotational velocity effects

2007 ◽  
Vol 328 (9) ◽  
pp. 938-947 ◽  
Author(s):  
K. Biazzo ◽  
A. Frasca ◽  
S. Catalano ◽  
E. Marilli
Keyword(s):  
Effective Temperature ◽  
Rotational Velocity ◽  
Depth Ratio ◽  
Line Depth

scholarly journals A photospheric and chromospheric activity analysis of the quiescent retrograde-planet host ν Octantis A

2021 ◽  
Vol 502 (2) ◽  
pp. 2793-2806
Author(s):  
D J Ramm ◽  
P Robertson ◽  
S Reffert ◽  
F Gunn ◽  
T Trifonov ◽  
...  
Keyword(s):  
Semimajor Axis ◽  
Spectroscopic Studies ◽  
Additional Line ◽  
Stellar Orbits ◽  
Qualitative And Quantitative ◽  
Spectroscopic Binary ◽  
Analysis Models ◽  
Large Survey ◽  
New Evidence ◽  
Line Depth

ABSTRACT The single-lined spectroscopic binary ν Octantis provided evidence of the first conjectured circumstellar planet demanding an orbit retrograde to the stellar orbits. The planet-like behaviour is now based on 1437 radial velocities (RVs) acquired from 2001 to 2013. ν Oct’s semimajor axis is only 2.6 au with the candidate planet orbiting $\nu ~{\rm Oct\, A}$ about mid-way between. These details seriously challenge our understanding of planet formation and our decisive modelling of orbit reconfiguration and stability scenarios. However, all non-planetary explanations are also inconsistent with numerous qualitative and quantitative tests including previous spectroscopic studies of bisectors and line-depth ratios, photometry from Hipparcos and the more recent space missions TESS and Gaia (whose increased parallax classifies $\nu ~{\rm Oct\, A}$ closer still to a subgiant, ∼K1 IV). We conducted the first large survey of $\nu ~{\rm Oct\, A}$’s chromosphere: 198 $\rm Ca\,{\small II}$ H-line and 1160 $\rm {H}\, \alpha$ indices using spectra from a previous RV campaign (2009–2013). We also acquired 135 spectra (2018–2020) primarily used for additional line-depth ratios, which are extremely sensitive to the photosphere’s temperature. We found no significant RV-correlated variability. Our line-depth ratios indicate temperature variations of only ±4 K, as achieved previously. Our atypical $\rm Ca\,{\small II}$ analysis models the indices in terms of S/N and includes covariance significantly in their errors. The $\rm {H}\, \alpha$ indices have a quasi-periodic variability that we demonstrate is due to telluric lines. Our new evidence provides further multiple arguments realistically only in favour of the planet.

Some Results of the Spectroscopic Study of Four Close Binary Systems of Early Spectral Types

1965 ◽  
Vol 5 ◽  
pp. 120-130
Author(s):  
T. S. Galkina
Keyword(s):  
Spectroscopic Study ◽  
Spectral Type ◽  
Spectroscopic Investigation ◽  
Binary Systems ◽  
Quantitative Information ◽  
Close Binary ◽  
Physical Parameters ◽  
Absorption And Emission ◽  
Close Binary Systems ◽  
Quantitative Estimates

It is necessary to have quantitative estimates of the intensity of lines (both absorption and emission) to obtain the physical parameters of the atmosphere of components.Some years ago at the Crimean observatory we began the spectroscopic investigation of close binary systems of the early spectral type with components WR, Of, O, B to try and obtain more quantitative information from the study of the spectra of the components.

Quasi-Periodic Oscillations in Dwarf Novae

1979 ◽  
Vol 46 ◽  
pp. 77-88
Author(s):  
Edward L. Robinson
Keyword(s):  
Binary Systems ◽  
Outer Edge ◽  
Light Curves ◽  
Close Binary ◽  
Bright Spot ◽  
Dwarf Novae ◽  
Periodic Oscillations ◽  
High Frequencies ◽  
Short Period ◽  
Typical Time

Three distinct kinds of rapid variations have been detected in the light curves of dwarf novae: rapid flickering, short period coherent oscillations, and quasi-periodic oscillations. The rapid flickering is seen in the light curves of most, if not all, dwarf novae, and is especially apparent during minimum light between eruptions. The flickering has a typical time scale of a few minutes or less and a typical amplitude of about .1 mag. The flickering is completely random and unpredictable; the power spectrum of flickering shows only a slow decrease from low to high frequencies. The observations of U Gem by Warner and Nather (1971) showed conclusively that most of the flickering is produced by variations in the luminosity of the bright spot near the outer edge of the accretion disk around the white dwarf in these close binary systems.

Systematic effects in observed parallaxes

1978 ◽  
Vol 48 ◽  
pp. 31-35
Author(s):  
R. B. Hanson
Keyword(s):  
Error Estimates ◽  
Zero Point ◽  
Absolute Zero ◽  
Apparent Magnitude ◽  
Coherent System ◽  
Preliminary Results ◽  
General Catalogue ◽  
Systematic Effects ◽  
New Evidence ◽  
Right Ascension

Several outstanding problems affecting the existing parallaxes should be resolved to form a coherent system for the new General Catalogue proposed by van Altena, as well as to improve luminosity calibrations and other parallax applications. Lutz has reviewed several of these problems, such as: (A) systematic differences between observatories, (B) external error estimates, (C) the absolute zero point, and (D) systematic observational effects (in right ascension, declination, apparent magnitude, etc.). Here we explore the use of cluster and spectroscopic parallaxes, and the distributions of observed parallaxes, to bring new evidence to bear on these classic problems. Several preliminary results have been obtained.

MERLIN Finds New Evidence of Ranolazine Safety

2007 ◽  
Vol 40 (9) ◽  
pp. 36
Author(s):  
BRUCE JANCIN
Keyword(s):  
New Evidence

Vaccination for travellers – new evidence and recommendations

2001 ◽  
Vol 58 (6) ◽  
pp. 362-366 ◽  
Author(s):  
Matius P. Stürchler ◽  
R. P. Steffen
Keyword(s):  
Hepatitis B ◽  
Hepatitis A ◽  
New Evidence

Impfungen sind einfache und effektive Maßnahmen zur Verhinderung von Reisekrankheiten. Compliance-Probleme sind gering, da alle Impfungen noch vor Abreise verabreicht werden und bei manchen Impfungen nur eine Dosis für den zuverlässigen Schutz nötig ist. Für jeden Reisenden sind die Hepatitis A- und die Diphtherie-Tetanus-Impfung empfohlen, für Asien und Afrika auch die Polioimpfung. Bei Reisen >30 Tagen, jüngeren Personen und Reisenden mit Risikoverhalten sollte immer auch eine Hepatitis B-Impfung, eventuell als Kombination mit Hepatitis A in Betracht gezogen werden. Je nach Reisestil, -destination und -dauer können auch weitere Impfungen wie z.B. die Typhus-, Tollwut-, Zeckenenzephalitis-, Grippe-, Masern-Mumps-Röteln-, Gelbfieber-, Meningokokkenmeningitis- und die Japanische Enzephalitis-Impfung in Frage kommen. Mehrere Impfungen können gleichzeitig verabreicht werden – eine Staffelung ist nicht nötig. i BAG Supplementum VI, Stand Juli 2000 «Impfungen für Auslandreisende»; http://www.admin.ch/bag/infekt/prev/reisemed/index.htm; Safetravel http://www.safetravel.ch; Tropimed

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