scholarly journals Echelle-Mepsicron Time-Resolved Spectroscopy of the Dwarf Nova SS Cygni

1987 ◽  
Vol 93 ◽  
pp. 111-111
Author(s):  
J. Echevarría ◽  
F. Diego ◽  
M. Tapia ◽  
R. Costero
Keyword(s):  
Radial Velocity ◽  
Hot Spot ◽  
High Dispersion ◽  
Velocity Measurements ◽  
Time Resolved ◽  
Line System ◽  
Narrow Component ◽  
Dwarf Nova ◽  
Chromospheric Emission ◽  
The Masses

AbstractHigh dispersion time-resolved spectrograms of the dwarf nova SS Cygni, obtained with the Echelle-Mepsicron system, show double peaked emission lines with a complex profile. The intensity of the Hβ line appears to be modulated by the orbital period. Radial velocity measurements of the wings of Hβ and of the absorption line system of the late-type star yield semiamplitude values of Kem = 101 ± 6 km s−1 and Kab = 151 ± 7 km s−1, respectively. Radial velocity measurements of the blue and red peaks and of the central absorption of Hβ reveal a synchronous movement with the broad wings, although there is some evidence of a narrow component probably associated with a hot spot in the disk or a chromospheric emission line from the secondary star. The Hβ modulation, the double profile and recently discovered UBV light variations support an inclination angle i ~ 50°. The masses of the primary and secondary stars using this angle and the observed semiamplitudes are Mp = 0.60 M⊙ and Ms = 0.40 M⊙, respectively. A detailed analysis of the absorption lines reveals a spectral type of K2V.

scholarly journals Densified Pupil Spectrograph as High-precision Radial Velocimetry: From Direct Measurement of the Universe’s Expansion History to Characterization of Nearby Habitable Planet Candidates

2022 ◽  
Vol 163 (2) ◽  
pp. 63
Author(s):  
Taro Matsuo ◽  
Thomas P. Greene ◽  
Mahdi Qezlou ◽  
Simeon Bird ◽  
Kiyotomo Ichiki ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Direct Measurement ◽  
High Precision ◽  
Resolving Power ◽  
Line Of Sight ◽  
High Dispersion ◽  
Velocity Measurements ◽  
Habitable Planet ◽  
Airy Disk

Abstract The direct measurement of the universe’s expansion history and the search for terrestrial planets in habitable zones around solar-type stars require extremely high-precision radial-velocity measures over a decade. This study proposes an approach for enabling high-precision radial-velocity measurements from space. The concept presents a combination of a high-dispersion densified pupil spectrograph and a novel line-of-sight monitor for telescopes. The precision of the radial-velocity measurements is determined by combining the spectrophotometric accuracy and the quality of the absorption lines in the recorded spectrum. Therefore, a highly dispersive densified pupil spectrograph proposed to perform stable spectroscopy can be utilized for high-precision radial-velocity measures. A concept involving the telescope’s line-of-sight monitor is developed to minimize the change of the telescope’s line of sight over a decade. This monitor allows the precise measurement of long-term telescope drift without any significant impact on the Airy disk when the densified pupil spectra are recorded. We analytically derive the uncertainty of the radial-velocity measurements, which is caused by the residual offset of the lines of sight at two epochs. We find that the error could be reduced down to approximately 1 cm s−1, and the precision will be limited by another factor (e.g., wavelength calibration uncertainty). A combination of the high-precision spectrophotometry and the high spectral resolving power could open a new path toward the characterization of nearby non-transiting habitable planet candidates orbiting late-type stars. We present two simple and compact highly dispersed densified pupil spectrograph designs for cosmology and exoplanet sciences.

scholarly journals Recovering saturated images for high dynamic kernel-phase analysis

2019 ◽  
Vol 623 ◽  
pp. A164 ◽  
Author(s):  
R. Laugier ◽  
F. Martinache ◽  
A. Ceau ◽  
D. Mary ◽  
M. N’Diaye ◽  
...  
Keyword(s):  
Point Source ◽  
Radial Velocity ◽  
Angular Resolution ◽  
Dynamic Range ◽  
Point Sources ◽  
Velocity Measurements ◽  
Orbital Parameters ◽  
High Dynamic ◽  
The Masses ◽  
Imaging Sensors

Kernel-phase observables extracted from mid- to high-Strehl images are proving to be a powerful tool to probe within a few angular resolution elements of point sources. The attainable contrast is limited, however, by the dynamic range of the imaging sensors. The Fourier interpretation of images with pixels exposed beyond the saturation has so far been avoided. In cases where the image is dominated by the light of a point source, we show that we can use an interpolation to reconstruct the otherwise lost pixels with an accuracy sufficient to enable the extraction of kernel-phases from the patched image. We demonstrate the usability of our method by applying it to archive images of the Gl 494AB system taken with the Hubble Space Telescope in 1997. Using this new data point along with other resolved observations and radial velocity measurements, we produce improved constraints on the orbital parameters of the system, and consequently the masses of its components.

scholarly journals The CARMENES search for exoplanets around M dwarfs

2020 ◽  
Vol 637 ◽  
pp. A93
Author(s):  
E. González-Álvarez ◽  
M. R. Zapatero Osorio ◽  
J. A. Caballero ◽  
J. Sanz-Forcada ◽  
V. J. S. Béjar ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Sierra Nevada ◽  
Stellar Rotation ◽  
Velocity Measurements ◽  
M Dwarfs ◽  
Earth Planet ◽  
Binary Orbit ◽  
The Masses ◽  
Astrometric Data ◽  
Parent Star

Aims. We report on radial velocity time series for two M0.0 V stars, GJ 338 B and GJ 338 A, using the CARMENES spectrograph, complemented by ground-telescope photometry from Las Cumbres and Sierra Nevada observatories. We aim to explore the presence of small planets in tight orbits using the spectroscopic radial velocity technique. Methods. We obtained 159 and 70 radial velocity measurements of GJ 338 B and A, respectively, with the CARMENES visible channel between 2016 January and 2018 October. We also compiled additional relative radial velocity measurements from the literature and a collection of astrometric data that cover 200 a of observations to solve for the binary orbit. Results. We found dynamical masses of 0.64 ± 0.07 M⊙ for GJ 338 B and 0.69 ± 0.07 M⊙ for GJ 338 A. The CARMENES radial velocity periodograms show significant peaks at 16.61 ± 0.04 d (GJ 338 B) and 16.3−1.3+3.5 d (GJ 338 A), which have counterparts at the same frequencies in CARMENES activity indicators and photometric light curves. We attribute these to stellar rotation. GJ 338 B shows two additional, significant signals at 8.27 ± 0.01 and 24.45 ± 0.02 d, with no obvious counterparts in the stellar activity indices. The former is likely the first harmonic of the star’s rotation, while we ascribe the latter to the existence of a super-Earth planet with a minimum mass of 10.27−1.38+1.47 M⊕ orbiting GJ 338 B. We have not detected signals of likely planetary origin around GJ 338 A. Conclusions. GJ 338 Bb lies inside the inner boundary of the habitable zone around its parent star. It is one of the least massive planets ever found around any member of stellar binaries. The masses, spectral types, brightnesses, and even the rotational periods are very similar for both stars, which are likely coeval and formed from the same molecular cloud, yet they differ in the architecture of their planetary systems.

scholarly journals Red Spectroscopy of IP Pegasi

1987 ◽  
Vol 93 ◽  
pp. 145-149
Author(s):  
J.S. Martin ◽  
D.H.P. Jones ◽  
R.C Smith
Keyword(s):  
Radial Velocity ◽  
Cross Correlation ◽  
Main Sequence ◽  
Mass Function ◽  
Velocity Curve ◽  
Absorption Lines ◽  
Radial Velocity Curve ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Dwarf Nova

AbstractTime resolved spectroscopy of the dwarf nova IP Pegasi in the range λλ 7670–8320Å shows absorption lines originating from the cool secondary. A radial velocity curve for this component has been derived by cross-correlation with a normal M star. The curve has semi-amplitude K2 = 288.3 ± 4 km s−1, and is slightly distorted. This distortion is equivalent to an orbit with an apparent eccentricity of 0.075 ± 0.024. The mass function of the primary is 0.394 ± 0.016M⊙. From this we derive constraints on the component masses of 0.62 < M1 < 1.14M⊙ and 0.17 < M2 < 0.71M⊙. The red star has a radius in the range 0.32 < R2 < 0.51R⊙ and is probably on the main sequence.

scholarly journals High precision radial-velocity measurements of late-type evolved stars

1999 ◽  
Vol 170 ◽  
pp. 204-210 ◽  
Author(s):  
I.N. Cummings ◽  
J.B. Hearnshaw ◽  
P.M. Kilmartin ◽  
A.C. Gilmore
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Spectral Type ◽  
Cross Correlation ◽  
Radial Velocities ◽  
High Dispersion ◽  
Late Type ◽  
Velocity Measurements ◽  
Evolved Stars ◽  
Type K

AbstractHigh dispersion spectra for 44 southern evolved stars of spectral type K or M have been obtained. From these observations relative radial velocities of 50 m/s precision have been obtained by the method of digital cross-correlation. This method of achieving precise relative radial velocities for late-type stars, and the problems encountered in its use, are discussed. Using this method, statistically significant radial-velocity variations have been found. Two of the observed stars have their precise radial velocities presented and the potential mechanisms of their variation examined.

scholarly journals Time-Resolved Optical Spectroscopy of AM Her X-Ray Sources

1987 ◽  
Vol 93 ◽  
pp. 613-624
Author(s):  
M. Mouchet ◽  
S.F. Van Amerongen ◽  
J.M. Bonnet-Bidaud ◽  
J.P. Osborne
Keyword(s):  
Radial Velocity ◽  
Time Resolution ◽  
Emission Lines ◽  
High Time Resolution ◽  
Rapid Variability ◽  
Time Resolved ◽  
X Ray ◽  
Narrow Component ◽  
Broad Component

AbstractWe present high-time resolution spectroscopy of two AM Her sources E1405−451 and E1013−477. For E1405−451, the Balmer emission lines profiles can be divided into a narrow component and a broad one. The amplitudes of the radial velocity curves of these components are respectively 265±30 km/s and 390±50 km/s. The orientation of the column determined from polarimetry is not compatible with the broad component being formed in the lowest parts of the column. Photometric and spectroscopic results on E1013−477 do not confirm the previous reported 103 min. period. Rapid variability (<1.5h) as well as long term modulation (>3.3h) is present in these data.

scholarly journals Another Superdense Sub-Neptune in K2-182 b and Refined Mass Measurements for K2-199 b and c*

2021 ◽  
Vol 162 (6) ◽  
pp. 294
Author(s):  
Joseph M. Akana Murphy ◽  
Molly R. Kosiarek ◽  
Natalie M. Batalha ◽  
Erica J. Gonzales ◽  
Howard Isaacson ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Velocity Data ◽  
Velocity Measurements ◽  
Mass Measurements ◽  
Data Set ◽  
Valuable Data ◽  
Data Points ◽  
The Masses ◽  
Radial Velocity Data ◽  
Intermediate Density

Abstract We combine multiple campaigns of K2 photometry with precision radial velocity measurements from Keck-HIRES to measure the masses of three sub-Neptune-sized planets. We confirm the planetary nature of the massive sub-Neptune K2-182 b (P b = 4.7 days, R b = 2.69 R ⊕) and derive refined parameters for K2-199 b and c (P b = 3.2 days, R b = 1.73 R ⊕ and P c = 7.4 days, R c = 2.85 R ⊕). These planets provide valuable data points in the mass–radius plane, especially as TESS continues to reveal an increasingly diverse sample of sub-Neptunes. The moderately bright (V = 12.0 mag) early K dwarf K2-182 (EPIC 211359660) was observed during K2 campaigns 5 and 18. We find that K2-182 b is potentially one of the densest sub-Neptunes known to date (20 ± 5 M ⊕ and 5.6 ± 1.4 g cm−3). The K5V dwarf K2-199 (EPIC 212779596; V = 12.3 mag), observed in K2 campaigns 6 and 17, hosts two recently confirmed planets. We refine the orbital and planetary parameters for K2-199 b and c by modeling both campaigns of K2 photometry and adding 12 Keck-HIRES measurements to the existing radial velocity data set (N = 33). We find that K2-199 b is likely rocky, at 6.9 ± 1.8 M ⊕ and 7.2 − 2.0 + 2.1 g cm−3, and that K2-199 c has an intermediate density at 12.4 ± 2.3 M ⊕ and 2.9 − 0.6 + 0.7 g cm−3. We contextualize these planets on the mass–radius plane, discuss a small but intriguing population of “superdense” sub-Neptunes (R p < 3 R ⊕, M p >20 M ⊕), and consider our prospects for the planets’ atmospheric characterization.

Spectroscopic Observations of Visual Double Stars

1965 ◽  
Vol 5 ◽  
pp. 109-111
Author(s):  
Frederick R. West
Keyword(s):  
Radial Velocity ◽  
High Dispersion ◽  
Velocity Difference ◽  
Spectrograph Slit ◽  
Spectroscopic Observations ◽  
Double Stars ◽  
Visual Double Stars ◽  
Relative Orbit ◽  
Two Component ◽  
Star Images

There are certain visual double stars which, when close to a node of their relative orbit, should have enough radial velocity difference (10-20 km/s) that the spectra of the two component stars will appear resolved on high-dispersion spectrograms (5 Å/mm or less) obtainable by use of modern coudé and solar spectrographs on bright stars. Both star images are then recorded simultaneously on the spectrograph slit, so that two stellar components will appear on each spectrogram.

scholarly journals Radial-velocity search and statistical studies for short-period planets in the Pleiades open cluster

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Takuya Takarada ◽  
Bun’ei Sato ◽  
Masashi Omiya ◽  
Yasunori Hori ◽  
Michiko S Fujii
Keyword(s):  
Radial Velocity ◽  
Open Cluster ◽  
Open Clusters ◽  
Occurrence Rate ◽  
High Dispersion ◽  
Echelle Spectrograph ◽  
Upper Limit ◽  
Stringent Constraint ◽  
Short Period ◽  
Statistical Studies

Abstract We report on a radial-velocity search for short-period planets in the Pleiades open cluster. We observed 30 Pleiades member stars at the Okayama Astrophysical Observatory with the High Dispersion Echelle Spectrograph. To evaluate and mitigate the effects of stellar activity on radial-velocity (RV) measurements, we computed four activity indicators (full width at half maximum, Vspan, Wspan, and SHα). Among our sample, no short-period planet candidates were detected. Stellar intrinsic RV jitter was estimated to be 52 m s−1, 128 m s−1, and 173 m s−1 for stars with $v$ sin i of 10 km s−1, 15 km s−1, and 20 km s−1, respectively. We determined the planet occurrence rate from our survey and set the upper limit to 11.4% for planets with masses 1–13 MJUP and period 1–10 d. To set a more stringent constraint on the planet occurrence rate, we combined the result of our survey with those of other surveys targeting open clusters with ages in the range 30–300 Myr. As a result, the planet occurrence rate in young open clusters was found to be less than 7.4%, 2.9%, and 1.9% for planets with an orbital period of 3 d and masses of 1–5, 5–13, and 13–80 MJUP, respectively.

Sign in / Sign up

Export Citation Format

Share Document