scholarly journals A long-period (P = 61.8 d) M5V dwarf eclipsing a Sun-like star from TESS and NGTS

2020 ◽  
Vol 495 (3) ◽  
pp. 2713-2719 ◽  
Author(s):  
Samuel Gill ◽  
Benjamin F Cooke ◽  
Daniel Bayliss ◽  
Louise D Nielsen ◽  
Monika Lendl ◽  
...  
Keyword(s):  
South Africa ◽  
Radial Velocity ◽  
Stellar Evolution ◽  
Orbital Period ◽  
Next Generation ◽  
Velocity Measurements ◽  
Long Period ◽  
Better Than

ABSTRACT The Transiting Exoplanet Survey Satellite has produced a large number of single-transit event candidates which are being monitored by the Next Generation Transit Survey (NGTS). We observed a second epoch for the TIC-231005575 system (Tmag = 12.06 and $T_{\rm eff} = 5500 \pm 85\, \mathrm{ K}$) with NGTS and a third epoch with Las Cumbres Observatory’s telescope in South Africa to constrain the orbital period ($P = 61.777\, \mathrm{ d}$). Subsequent radial velocity measurements with CORALIE revealed the transiting object has a mass of M2 = 0.128 ± 0.003 M⊙, indicating the system is a G-M binary. The radius of the secondary is R2 = 0.154 ± 0.008 R⊙ and is consistent with mesa models of stellar evolution to better than 1σ.

scholarly journals NGTS and WASP photometric recovery of a single-transit candidate from TESS

2019 ◽  
Author(s):  
Samuel Gill ◽  
Daniel Bayliss ◽  
Benjamin F Cooke ◽  
Peter J Wheatley ◽  
Louise D Nielsen ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Stellar Evolution ◽  
Orbital Period ◽  
Eclipsing Binaries ◽  
Dwarf Star ◽  
Velocity Measurements ◽  
Eclipsing Binary ◽  
Long Period ◽  
M Dwarf

Abstract The Transiting Exoplanet Survey Satellite (TESS) produces a large number of single-transit event candidates, since the mission monitors most stars for only ∼27 days. Such candidates correspond to long-period planets or eclipsing binaries. Using the TESS Sector 1 full-frame images, we identified a 7750 ppm single-transit event with a duration of 7 hours around the moderately evolved F-dwarf star TIC-238855958 (Tmag=10.23, Teff=6280±85 K). Using archival WASP photometry we constrained the true orbital period to one of three possible values. We detected a subsequent transit-event with NGTS, which revealed the orbital period to be 38.20 d. Radial velocity measurements from the CORALIE Spectrograph show the secondary object has a mass of M2= 0.148 ± 0.003 M⊙, indicating this system is an F-M eclipsing binary. The radius of the M-dwarf companion is R2 = 0.171 ± 0.003 R⊙, making this one of the most well characterised stars in this mass regime. We find that its radius is 2.3-σ lower than expected from stellar evolution models.

scholarly journals NGTS-12b: A sub-Saturn mass transiting exoplanet in a 7.53 day orbit

2020 ◽  
Vol 499 (3) ◽  
pp. 3139-3148
Author(s):  
Edward M Bryant ◽  
Daniel Bayliss ◽  
Louise D Nielsen ◽  
Dimitri Veras ◽  
Jack S Acton ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Effective Temperature ◽  
Low Density ◽  
Next Generation ◽  
Velocity Measurements ◽  
Long Period ◽  
Transmission Spectroscopy ◽  
Stellar Properties

ABSTRACT We report the discovery of the transiting exoplanet NGTS-12b by the Next Generation Transit Survey (NGTS). The host star, NGTS-12, is a V = 12.38 mag star with an effective temperature of Teff = 5690 ± 130 K. NGTS-12b orbits with a period of P = 7.53 d, making it the longest period planet discovered to date by the main NGTS survey. We verify the NGTS transit signal with data extracted from the Transiting Exoplanet Survey Satellite (TESS) full-frame images, and combining the photometry with radial velocity measurements from HARPS and FEROS we determine NGTS-12b to have a mass of 0.208 ± 0.022 MJ and a radius of 1.048 ± 0.032 RJ. NGTS-12b sits on the edge of the Neptunian desert when we take the stellar properties into account, highlighting the importance of considering both the planet and star when studying the desert. The long period of NGTS-12b combined with its low density of just 0.223 ± 0.029 g cm−3 make it an attractive target for atmospheric characterization through transmission spectroscopy with a Transmission Spectroscopy Metric of 89.4.

scholarly journals Applications of a Velocity Dealiasing Scheme to Data from the China New Generation Weather Radar System (CINRAD)

2012 ◽  
Vol 27 (1) ◽  
pp. 218-230 ◽  
Author(s):  
Guangxin He ◽  
Gang Li ◽  
Xiaolei Zou ◽  
Peter Sawin Ray
Keyword(s):  
Radial Velocity ◽  
Weather Radar ◽  
Heavy Rain ◽  
Radar System ◽  
Squall Line ◽  
Next Generation ◽  
Velocity Measurements ◽  
Squall Lines ◽  
New Generation ◽  
Better Than

Abstract An improved velocity dealiasing algorithm is developed as an extension of the Next Generation Weather Radar (NEXRAD) dealiasing algorithm. The algorithm described in this paper is evaluated on selected China Next Generation Weather Radar (CINRAD) S-band radar radial velocity observations. This algorithm includes four modules for removing weak signals and determining the starting radial as a prelude to identifying and correcting aliased velocities. The proposed dealiasing algorithm was tested on 14 different weather systems, composed of typhoons, squall lines, and heavy rains. The results show that the algorithm is robust and stable for dealiasing S-band CINRAD radial velocity measurements. The performance levels for the typhoon and heavy rain cases are slightly better than for squall-line cases.

scholarly journals TOI-222: a single-transit TESS candidate revealed to be a 34-d eclipsing binary with CORALIE, EulerCam, and NGTS

2019 ◽  
Vol 492 (2) ◽  
pp. 1761-1769 ◽  
Author(s):  
Monika Lendl ◽  
François Bouchy ◽  
Samuel Gill ◽  
Louise D Nielsen ◽  
Oliver Turner ◽  
...  
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Orbital Period ◽  
Mass Star ◽  
Mass Determination ◽  
Velocity Measurements ◽  
Eclipsing Binary ◽  
Photometric Detection ◽  
Long Period ◽  
Low Mass

ABSTRACT We report the period, eccentricity, and mass determination for the Transiting Exoplanet Survey Satellite (TESS) single-transit event candidate TOI-222, which displayed a single 3000 ppm transit in the TESS 2-min cadence data from Sector 2. We determine the orbital period via radial velocity measurements (P = 33.9 d), which allowed for ground-based photometric detection of two subsequent transits. Our data show that the companion to TOI-222 is a low-mass star, with a radius of $0.18_{-0.10}^{+0.39}$ R⊙ and a mass of 0.23 ± 0.01 M⊙. This discovery showcases the ability to efficiently discover long-period systems from TESS single-transit events using a combination of radial velocity monitoring coupled with high-precision ground-based photometry.

scholarly journals The empirical period-radius relation for pulsating stars: a synthesis based on photometric and radial velocity measurements

1986 ◽  
Vol 118 ◽  
pp. 273-274
Author(s):  
G. Burki
Keyword(s):  
Radial Velocity ◽  
Stellar Evolution ◽  
Variable Stars ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
Pulsating Stars ◽  
Powerful Test ◽  
The Mean

The relation existing between the radius and the period for the pulsating stars of a given class constitutes a powerful test for the theory of stellar evolution and for the identification of the pulsation modes. In recent years, several authors have determined the mean radius of a lot of pulsating stars of various classes by applying the Baade-Wesselink method. Fig. 1 presents the resulting general logP - logR diagram grouping these determinations. The sources for the radii are given by Burki and Meylan (1986). The variable stars in known binaries have been excluded since the presence of a companion biases the radius calculation (Burki, 1984). The determinations marked by arrows are based on the radial velocities by CORAVEL (1m telescope at the Haute-Provence Observatory, France) or/and on the photometry in the Geneva system (40cm and 70cm telescopes at La Silla Observatory, Chile).

scholarly journals Proxima’s orbit around α Centauri

2017 ◽  
Vol 598 ◽  
pp. L7 ◽  
Author(s):  
P. Kervella ◽  
F. Thévenin ◽  
C. Lovis
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Orbital Period ◽  
Triple System ◽  
Orbital Motion ◽  
The Sun ◽  
Proper Motions ◽  
Velocity Measurements ◽  
Degree Of Confidence ◽  
High Degree

Proxima and α Centauri AB have almost identical distances and proper motions with respect to the Sun. Although the probability of such similar parameters is, in principle, very low, the question as to whether they actually form a single gravitationally bound triple system has been open since the discovery of Proxima one century ago. Owing to HARPS high-precision absolute radial velocity measurements and the recent revision of the parameters of the α Cen pair, we show that Proxima and α Cen are gravitationally bound with a high degree of confidence. The orbital period of Proxima is ≈ 550 000 yr. With an eccentricity of 0.50+0.08-0.09, Proxima comes within 4.3+1.1-0.9 kau of α Cen at periastron, and is currently close to apastron (13.0+0.3-0.1 kau). This orbital motion may have influenced the formation or evolution of the recently discovered planet orbiting Proxima, as well as circumbinary planet formation around α Cen.

scholarly journals Phase connected X-ray light curve and He II radial velocity measurements of NGC 300 X-1

2018 ◽  
Vol 14 (S346) ◽  
pp. 187-192
Author(s):  
S. Carpano ◽  
F. Haberl ◽  
P. Crowther ◽  
A. Pollock
Keyword(s):  
Black Hole ◽  
Light Curve ◽  
Radial Velocity ◽  
Orbital Period ◽  
High Mass ◽  
Velocity Measurements ◽  
X Ray ◽  
Black Hole Radiation ◽  
Ic 10 ◽  
Binary Evolution

Abstract. NGC 300 X-1 and IC 10 X-1 are currently the only two robust extragalactic candidates for being Wolf-Rayet/black hole X-ray binaries, the Galactic analogue being Cyg X-3. These systems are believed to be a late product of high-mass X-ray binary evolution and direct progenitors of black hole mergers. From the analysis of Swift data, the orbital period of NGC 300 X-1 was found to be 32.8 h. We here merge the full set of existing data of NGC 300 X-1, using XMM-Newton, Chandra and Swift observations to derive a more precise value of the orbital period of 32.7932 ± 0.0029 h above a confidence level of 99.99%. This allows us to phase connect the X-ray light curve of the source with radial velocity measurements of He II lines performed in 2010. We show that, as for IC 10 X-1 and Cyg X-3, the X-ray eclipse corresponds to maximum of the blueshift of the He II lines, instead of the expected zero velocity. This indicates that for NGC 300 X-1 as well, the wind of the WR star is completely ionised by the black hole radiation and that the emission lines come from the region of the WR star that is in the shadow. We also present for the first time the light curve of two recent very long XMM-Newton observations of the source, performed on the 16th to 20th of December 2016.

scholarly journals The ELODIE and SOPHIE Search for Northern Extrasolar Planets: Jupiter-Analogs around Sun-Like Stars

2012 ◽  
Vol 8 (S293) ◽  
pp. 445-447
Author(s):  
I. Boisse ◽  
F. Pepe ◽  
C. Perrier ◽  
D. Queloz ◽  
F. Bouchy ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Extrasolar Planets ◽  
Velocity Measurements ◽  
Long Period

AbstractWe present radial-velocity measurements (RV) obtained in one of the numbers of programs underway to search for extrasolar planets with the spectrograph SOPHIE at the 1.93-m telescope of the Observatoire de Haute-Provence. Targets were selected from catalogs observed with ELODIE, which had been mounted previously at the telescope, in order to detect long-period planets with an extended database close to 15 years.

scholarly journals Direct Imaging Of Long Period Radial Velocity Targets With NICI

2013 ◽  
Vol 8 (S299) ◽  
pp. 66-67
Author(s):  
Graeme S. Salter ◽  
Chris G. Tinney ◽  
Robert A. Wittenmyer ◽  
James S. Jenkins ◽  
Hugh R.A. Jones ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Minimum Mass ◽  
Post Processing ◽  
Velocity Measurements ◽  
Brown Dwarf ◽  
Direct Imaging ◽  
Parameter Spaces ◽  
Long Period ◽  
Imaging Parameter

AbstractWe are finally entering an era where radial velocity and direct imaging parameter spaces are starting to overlap. Radial velocity measurements provide us with a minimum mass for an orbiting companion (the mass as a function of the inclination of the system). By following up these long period radial velocity detections with direct imaging we can determine whether a trend seen is due to an orbiting planet at low inclination or an orbiting brown dwarf at high inclination. In the event of a non-detection we are still able to put a limit on the maximum mass of the orbiting body. The Anglo-Australian Planet Search is one of the longest baseline radial velocity planet searches in existence, amongst its targets are many that show long period trends in the data. Here we present our direct imaging survey of these objects with our results to date. ADI Observations have been made using NICI (Near Infrared Coronagraphic Imager) on Gemini South and analysed using an in house, LOCI-like, post processing.

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