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 ALMA and NACO observations towards the young exoring transit system J1407 (V1400 Cen)

2020 ◽  
Vol 633 ◽  
pp. A115 ◽  
Author(s):  
M. A. Kenworthy ◽  
P. D. Klaassen ◽  
M. Min ◽  
N. van der Marel ◽  
A. J. Bohn ◽  
...  
Keyword(s):  
Point Source ◽  
Thermal Emission ◽  
Angular Separation ◽  
Ring Structure ◽  
Ring System ◽  
Point Sources ◽  
Transit System ◽  
Orbital Parameters ◽  
Upper Limit ◽  
Infrared Wavelengths

Aims. Our aim was to directly detect the thermal emission of the putative exoring system responsible for the complex deep transits observed in the light curve for the young Sco-Cen star 1SWASP J140747.93-394542.6 (V1400 Cen, hereafter J1407), confirming it as the occulter seen in May 2007, and to determine its orbital parameters with respect to the star. Methods. We used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the field centred on J1407 in the 340 GHz (Band 7) continuum in order to determine the flux and astrometric location of the ring system relative to the star. We used the VLT/NACO camera to observe the J1407 system in March 2019 and to search for the central planetary mass object at thermal infrared wavelengths. Results. We detect no point source at the expected location of J1407, and derive an upper limit 3σ level of 57.6 μJy. There is a point source detected at an angular separation consistent with the expected location for a free-floating ring system that occulted J1407 in May 2007, with a flux of 89 μJy consistent with optically thin dust surrounding a massive substellar companion. At 3.8 μm with the NACO camera, we detect the star J1407 but no other additional point sources within 1.3 arcsec of the star, with a lower bound on the sensitivity of 6 MJup at the location of the ALMA source, and down to 4 MJup in the sky background limit. Conclusions. The ALMA upper limit at the location of J1407 implies that a hypothesised bound ring system is composed of dust smaller than 1 mm in size, implying a young ring structure. The detected ALMA source has multiple interpretations, including: (i) it is an unbound substellar object surrounded by warm dust in Sco-Cen with an upper mass limit of 6 MJup, or (ii) it is a background galaxy.

scholarly journals Derivation of orbital parameters of very low mass companions in double stars from radial velocities and observations of space astrometry missions like HIPPARCOS, DIVA and GAIA

1999 ◽  
Vol 170 ◽  
pp. 410-415
Author(s):  
H.-H. Bernstein
Keyword(s):  
Radial Velocity ◽  
Extrasolar Planets ◽  
Brown Dwarfs ◽  
Optimal Estimation ◽  
Velocity Measurements ◽  
Orbital Parameters ◽  
Double Stars ◽  
Observation Methods ◽  
Low Mass ◽  
Space Astrometry

AbstractRadial velocity measurements are a well known high-precision method to obtain the orbits of extrasolar planets or brown dwarfs. However, this method is not able to determine the inclination which could be derived from astrometry. The astrometric effects of those objects are very minute, wherefore the interest of astronomers in astrometric techniques was very poor. This situation changes fundamentally since space astrometry observations are available. HIPPARCOS demonstrated the power of space astrometry and the extremely high accuracy of the DIVA, and especially the GAIA observations allows one to detect Jupiter- and Earth- like objects. The optimal estimation of the parameters of the orbit of extrasolar planets or brown dwarfs is a combination of radial velocity measurements and space astrometry observations. Here it is possible to overcome problems which are inherent in both observation methods, so space astrometry complements radial velocity observations and vice versa. This paper gives a method for the parameter estimation using both types of measurements.

scholarly journals Periodic transit timing variations and refined system parameters of the exoplanet XO-6b

2019 ◽  
Author(s):  
Zoltán Garai ◽  
Theodor Pribulla ◽  
Richard Komžík ◽  
Emil Kundra ◽  
Ľubomír Hambálek ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Rotating Stars ◽  
Velocity Measurements ◽  
Orbital Parameters ◽  
Orbit Inclination ◽  
Consistent Solution ◽  
Low Mass ◽  
Academy Of Sciences ◽  
Fast Rotating

Abstract Only a few exoplanets are known to orbit around fast rotating stars. One of them is XO-6b, which orbits an F5V-type star. Shortly after the discovery, we started multicolor photometric and radial-velocity follow-up observations of XO-6b, using the telescopes of Astronomical Institute of the Slovak Academy of Sciences. Our main scientific goals were to better characterize the planetary system and to search for transit timing variations. We refined several planetary and orbital parameters. Based on our measurements, the planet XO-6b seems to be about 10% larger, which is, however, only about 2σ difference, but its orbit inclination angle, with respect to the plane of the sky, seems to be significantly smaller, than it was determined originally by the discoverers. In this case we found about 9.5σ difference. Moreover, we observed periodic transit timing variations of XO-6b with a semi-amplitude of about 14 min and with a period of about 450 days. There are two plausible explanations of such transit timing variations: (1) a third object in the system XO-6 causing light-time effect, or (2) resonant perturbations between the transiting planet XO-6b and another unknown low-mass planet in this system. From the O-C diagram we derived that the assumed third object in the system should have a stellar mass, therefore significant variations are expected in the radial-velocity measurements of XO-6. Since this is not the case, and since all attempts to fit radial velocities and O-C data simultaneously failed to provide a consistent solution, more realistic is the second explanation.

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 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.

Scheduling strategies for the ESPRESSO follow-up of TESS targets

2021 ◽  
Vol 503 (4) ◽  
pp. 5504-5521
Author(s):  
L Cabona ◽  
P T P Viana ◽  
M Landoni ◽  
J P Faria
Keyword(s):  
Radial Velocity ◽  
Planetary Systems ◽  
Data Set ◽  
Noise Component ◽  
Orbital Parameters ◽  
Transiting Planets ◽  
Accuracy And Precision ◽  
Scheduling Strategies ◽  
The Masses

ABSTRACT Radial-velocity follow-up of stars harbouring transiting planets detected by TESS is expected to require very large amounts of expensive telescope time in the next few years. Therefore, scheduling strategies should be implemented to maximize the amount of information gathered about the target planetary systems. We consider myopic and non-myopic versions of a novel uniform-in-phase scheduler, as well as a random scheduler, and compare these scheduling strategies with respect to the bias, accuracy and precision achieved in recovering the mass and orbital parameters of transiting and non-transiting planets. This comparison is carried out based on realistic simulations of radial-velocity follow-up with ESPRESSO of a sample of 50 TESS target stars, with simulated planetary systems containing at least one transiting planet with a radius below 4R⊕. Radial-velocity data sets were generated under reasonable assumptions about their noise component, including that resulting from stellar activity, and analysed using a fully Bayesian methodology. We find the random scheduler leads to a more biased, less accurate, and less precise, estimation of the mass of the transiting exoplanets. No significant differences are found between the results of the myopic and non-myopic implementations of the uniform-in-phase scheduler. With only about 22 radial velocity measurements per data set, our novel uniform-in-phase scheduler enables an unbiased (at the level of 1 per cent) measurement of the masses of the transiting planets, while keeping the average relative accuracy and precision around 16 per cent and 23 per cent, respectively. The number of non-transiting planets detected is similar for all the scheduling strategies considered, as well as the bias, accuracy and precision with which their masses and orbital parameters are recovered.

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.

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