Context. Ground-based high-dispersion (R ~ 100 000) spectroscopy (HDS) is proving to be a powerful technique with which to characterize extrasolar planets. The planet signal is distilled from the ...bright starlight, combining ral and time-differential filtering techniques. In parallel, high-contrast imaging (HCI) is developing rapidly, aimed at spatially separating the planet from the star. While HDS is limited by the overwhelming noise from the host star, HCI is limited by residual quasi-static speckles. Both techniques currently reach planet-star contrast limits down to ~10-5, albeit for very different types of planetary systems. Aims. In this work, we discuss a way to combine HDS and HCI (HDS+HCI). For a planet located at a resolvable angular distance from its host star, the starlight can be reduced up to several orders of magnitude using adaptive optics and/or coronography. In addition, the remaining starlight can be filtered out using high-dispersion spectroscopy, utilizing the significantly different (or Doppler shifted) high-dispersion spectra of the planet and star. In this way, HDS+HCI can in principle reach contrast limits of ~10-5 × 10-5, although in practice this will be limited by photon noise and/or sky-background. In contrast to current direct imaging techniques, such as Angular Differential Imaging and Spectral Differential Imaging, it will work well at small working angles and is much less sensitive to speckle noise. For the discovery of previously unknown planets HDS+HCI requires a high-contrast adaptive optics system combined with a high-dispersion R ~ 100 000 integral field spectrograph (IFS). This combination currently does not exist, but is planned for the European Extremely Large Telescope. Methods. We present simulations of HDS+HCI observations with the E-ELT, both probing thermal emission from a planet at infrared wavelengths, and starlight reflected off a planet atmosphere at optical wavelengths. For the infrared simulations we use the baseline parameters of the E-ELT and METIS instrument, with the latter combining extreme adaptive optics with an R = 100 000 IFS. We include realistic models of the adaptive optics performance and atmospheric transmission and emission. For the optical simulation we also assume R = 100 000 IFS with adaptive optics capabilities at the E-ELT. Results. One night of HDS+HCI observations with the E-ELT at 4.8 μm (Δλ = 0.07 μm) can detect a planet orbiting α Cen A with a radius of R = 1.5 Rearth and a twin-Earth thermal spectrum of Teq = 300 K at a signal-to-noise (S/N) of 5. In the optical, with a Strehl ratio performance of 0.3, reflected light from an Earth-size planet in the habitable zone of Proxima Centauri can be detected at a S/N of 10 in the same time frame. Recently, first HDS+HCI observations have shown the potential of this technique by determining the spin-rotation of the young massive exoplanet β Pictoris b. Conclusions. The exploration of the planetary systems of our neighbor stars is of great scientific and philosophical value. The HDS+HCI technique has the potential to detect and characterize temperate rocky planets in their habitable zones. Exoplanet scientists should not shy away from claiming a significant fraction of the future ELTs to make such observations possible.
Context.
The Multi-site All-Sky CAmeRA (MASCARA) and bRing are both photometric ground-based instruments with multiple stations that rely on interline charge-coupled devices with wide-field lenses to ...monitor bright stars in the local sky for variability. MASCARA has already discovered several planets in the northern sky, which are among the brightest known transiting hot Jupiter systems.
Aims.
In this paper, we aim to characterize a transiting planetary candidate in the southern skies found in the combined MASCARA and bRing data sets of HD 85628, an A7V star of
V
= 8.2 mag at a distance 172 pc, to establish its planetary nature.
Methods.
The candidate was originally detected in data obtained jointly with the MASCARA and bRing instruments using a Box Least-Square search for transit events. Further photometry was taken by the 0.7 m Chilean-Hungarian Automated Telescope (CHAT), and radial velocity measurements with the Fiber Dual Echelle Optical Spectrograph on the European Southern Observatory 1.0 m Telescope. High-resolution spectra during a transit were taken with the CTIO high-resolution spectrometer (CHIRON) on the Small and Moderate Aperture Research Telescope System 1.5 m telescope to target the Doppler shadow of the candidate.
Results.
We confirm the existence of a hot Jupiter transiting the bright A7V star HD 85628, which we co-designate as MASCARA-4b and bRing-1b. It is in an orbit of 2.824 days, with an estimated planet radius of 1.53
−0.04
+0.07
R
Jup
and an estimated planet mass of 3.1 ± 0.9
M
Jup
, putting it well within the planetary regime. The CHAT observations show a partial transit, reducing the probability that the transit was around a faint background star. The CHIRON observations show a clear Doppler shadow, implying that the transiting object is in a retrograde orbit with |
λ
| =244.9
−3.6
+2.7
°. The planet orbits at a distance of 0.047 ± 0.004 AU from the star and has a zero-albedo equilibrium temperature of 2100 ± 100 K. In addition, we find that HD 85628 has a previously unreported stellar companion star in the
Gaia
DR2 data demonstrating common proper motion and parallax at 4.3′′ separation (projected separation ~740 AU), and with absolute magnitude consistent with being a K/M dwarf.
Conclusions.
MASCARA-4 b/bRing-1 b is the brightest transiting hot Jupiter known to date in a retrograde orbit. It further confirms that planets in near-polar and retrograde orbits are more common around early-type stars. Due to its high apparent brightness and short orbital period, the system is particularly well suited for further atmospheric characterization.
Context. The Multi-site All-Sky CAmeRA (MASCARA) aims to find the brightest transiting planet systems by monitoring the full sky at magnitudes 4 < V < 8.4, taking data every 6.4 s. The northern ...station has been operational on La Palma since February 2015. These data can also be used for other scientific purposes, such as the study of variable stars. Aims. In this paper we aim to assess the value of MASCARA data for studying variable stars by determining to what extent known variable stars can be recovered and characterised, and how well new, unknown variables can be discovered. Methods. We used the first 14 months of MASCARA data, consisting of the light curves of 53 401 stars with up to one million flux points per object. All stars were cross-matched with the VSX catalogue to identify known variables. The MASCARA light curves were searched for periodic flux variability using generalised Lomb–Scargle periodograms. If significant variability of a known variable was detected, the found period and amplitude were compared with those listed in the VSX database. If no previous record of variability was found, the data were phase folded to attempt a classification. Results. Of the 1919 known variable stars in the MASCARA sample with periods 0.1 < P < 10 days, amplitudes >2%, and that have more than 80 h of data, 93.5% are recovered. In addition, the periods of 210 stars without a previous VSX record were determined, and 282 candidate variable stars were newly identified. We also investigated whether second order variability effects could be identified. The O’Connell effect is seen in seven eclipsing binaries, of which two have no previous record of this effect. Conclusions. MASCARA data are very well suited to study known variable stars. They also serve as a powerful means to find new variables among the brightest stars in the sky. Follow-up is required to ensure that the observed variability does not originate from faint background objects.
Aims. We describe the design and first light observations from the β Pictoris b Ring (“bRing”) project. The primary goal is to detect photometric variability from the young star β Pictoris due to ...circumplanetary material surrounding the directly imaged young extrasolar gas giant planet β Pictoris b. Methods. Over a nine month period centred on September 2017, the Hill sphere of the planet will cross in front of the star, providing a unique opportunity to directly probe the circumplanetary environment of a directly imaged planet through photometric and spectroscopic variations. We have built and installed the first of two bRing monitoring stations (one in South Africa and the other in Australia) that will measure the flux of β Pictoris, with a photometric precision of 0.5% over 5 min. Each station uses two wide field cameras to cover the declination of the star at all elevations. Detection of photometric fluctuations will trigger spectroscopic observations with large aperture telescopes in order to determine the gas and dust composition in a system at the end of the planet-forming era. Results. The first three months of operation demonstrate that bRing can obtain better than 0.5% photometry on β Pictoris in five minutes and is sensitive to nightly trends enabling the detection of any transiting material within the Hill sphere of the exoplanet.
Aims. MASCARA and bRing are photometric surveys designed to detect variability caused by exoplanets in stars with mV < 8.4. Such variability signals are typically small and require an accurate ...calibration algorithm, tailored to the survey, in order to be detected. This paper presents the methods developed to calibrate the raw photometry of the MASCARA and bRing stations and characterizes the performance of the methods and instruments. Methods. For the primary calibration, a modified version of the coarse decorrelation algorithm is used, which corrects for the extinction due to the earth’s atmosphere, the camera transmission, and intrapixel variations. Residual trends are removed from the light curves of individual stars using empirical secondary calibration methods. In order to optimize these methods, as well as characterize the performance of the instruments, transit signals were injected in the data. Results. After optimal calibration an RMS scatter of 10 mmag at mV ~ 7.5 is achieved in the light curves. By injecting transit signals with periods between one and five days in the MASCARA data obtained by the La Palma station over the course of one year, we demonstrate that MASCARA La Palma is able to recover 84.0, 60.5 and 20.7% of signals with depths of 2, 1 and 0.5%, respectively, with a strong dependency on the observed declination, recovering 65.4% of all transit signals at δ > 0° versus 35.8% at δ < 0°. Using the full three years of data obtained by MASCARA La Palma to date, similar recovery rates are extended to periods up to ten days. We derive a preliminary occurrence rate for hot Jupiters around A-stars of >0.4%, knowing that many hot Jupiters are still overlooked. In the era of TESS, MASCARA and bRing will provide an interesting synergy for finding long-period (>13.5 days) transiting gas-giant planets around the brightest stars.
MASCARA-2 b Talens, G. J. J.; Justesen, A. B.; Albrecht, S. ...
Astronomy and astrophysics (Berlin),
04/2018, Letnik:
612
Journal Article
Recenzirano
Odprti dostop
In this paper we present MASCARA-2 b, a hot Jupiter transiting the mV = 7.6 A2 star HD 185603. Since early 2015, MASCARA has taken more than 1.6 million flux measurements of the star, corresponding ...to a total of almost 3000 h of observations, revealing a periodic dimming in the flux with a depth of 1.3%. Photometric follow-up observations were performed with the NITES and IAC80 telescopes and spectroscopic measurements were obtained with the Hertzsprung SONG telescope. We find MASCARA-2 b orbits HD 185603 with a period of $3.474119^{+0.000005}_{-0.000006}$3.4741119-0.000006+0.000005 days3.474119-0.000006+0.000005 days at a distance of 0.057 ± 0.006 au, has a radius of 1.83 ± 0.07 RJ and place a 99% upper limit on the mass of <17 MJ. HD 185603 is a rapidly rotating early-type star with an effective temperature of $8980^{+90}_{-130}$8980-130+908980-130+90 K and a mass and radius of $1.89^{+0.06}_{-0.05}$1.89-0.05+0.061.89-0.05+0.06 M⊙, 1.60 ± 0.06 R⊙, respectively. Contrary to most other hot Jupiters transiting early-type stars, the projected planet orbital axis and stellar spin axis are found to be aligned with λ = 0.6 ± 4°. The brightness of the host star and the high equilibrium temperature, 2260 ± 50 K, of MASCARA-2 b make it a suitable target for atmospheric studies from the ground and space. Of particular interest is the detection of TiO, which has recently been detected in the similarly hot planets WASP-33 b and WASP-19 b.
MASCARA-3b Hjorth, M.; Albrecht, S.; Talens, G. J. J. ...
Astronomy and astrophysics (Berlin),
11/2019, Letnik:
631
Journal Article
Recenzirano
Odprti dostop
We report the discovery of MASCARA-3b, a hot Jupiter orbiting its bright (V = 8.33) late F-type host every 5.55149 ± 0.00001 days in an almost circular orbit ( e = 0.050−0.017+0.020 $e = ...0.050^{+0.020}_{-0.017}$ e=0.050−0.017+0.020 ). This is the fourth exoplanet discovered with the Multi-site All-Sky CAmeRA (MASCARA), and the first of these that orbits a late-type star. Follow-up spectroscopic measurements were obtained in and out of transit with the Hertzsprung SONG telescope. Combining the MASCARA photometry and SONG radial velocities reveals a radius and mass of 1.36 ± 0.05 RJup and 4.2 ± 0.2 MJup. In addition, SONG spectroscopic transit observations were obtained on two separate nights. From analyzing the mean out-of-transit broadening function, we obtain v sin i⋆ = 20.4 ± 0.4 km s−1. In addition, investigating the Rossiter-McLaughlin effect, as observed in the distortion of the stellar lines directly and through velocity anomalies, we find the projected obliquity to be λ = 1.2−7.4+8.2 $\lambda = 1.2^{+8.2}_{-7.4}$λ=1.2−7.4+8.2 deg, which is consistent with alignment.
The Multi-site All-Sky CAmeRA (MASCARA) Talens, G. J. J.; Spronck, J. F. P.; Lesage, A.-L. ...
Astronomy and astrophysics (Berlin),
05/2017, Letnik:
601
Journal Article
Recenzirano
Odprti dostop
This paper describes the design, operations, and performance of the Multi-site All-Sky CAmeRA (MASCARA). Its primary goal is to find new exoplanets transiting bright stars, 4 < mV < 8, by monitoring ...the full sky. MASCARA consists of one northern station on La Palma, Canary Islands (fully operational since February 2015), one southern station at La Silla Observatory, Chile (operational from early 2017), and a data centre at Leiden Observatory in the Netherlands. Both MASCARA stations are equipped with five interline CCD cameras using wide field lenses (24 mm focal length) with fixed pointings, which together provide coverage down to airmass 3 of the local sky. The interline CCD cameras allow for back-to-back exposures, taken at fixed sidereal times with exposure times of 6.4 sidereal seconds. The exposures are short enough that the motion of stars across the CCD does not exceed one pixel during an integration. Astrometry and photometry are performed on-site, after which the resulting light curves are transferred to Leiden for further analysis. The final MASCARA archive will contain light curves for ~70 000 stars down to mV = 8.4, with a precision of 1.5% per 5 minutes at mV = 8.
MASCARA-1 b Talens, G. J. J.; Albrecht, S.; Spronck, J. F. P. ...
Astronomy and astrophysics (Berlin),
10/2017, Letnik:
606
Journal Article
Recenzirano
Odprti dostop
We report the discovery of MASCARA-1 b, which is the first exoplanet discovered with the Multi-site All-Sky CAmeRA (MASCARA). This exoplanet is a hot Jupiter orbiting a bright mV = 8.3, rapidly ...rotating (vsini⋆ > 100 km s-1) A8 star with a period of 2.148780 ± 8 × 10-6 days. The planet has a mass and radius of 3.7 ± 0.9 MJup and 1.5 ± 0.3 RJup, respectively. As with most hot Jupiters transiting early-type stars, we find a misalignment between the planet orbital axis and the stellar spin axis, which may be a signature of the formation and migration histories of this family of planets. MASCARA-1 b has a mean density of 1.5 ± 0.9 g cm-3 and an equilibrium temperature of 2570+50-30K, that is one of the highest temperatures known for a hot Jupiter to date. The system is reminiscent of WASP-33, but the host star lacks apparent delta-scuti variations, making the planet an ideal target for atmospheric characterization. We expect this to be the first of a series of hot Jupiters transiting bright early-type stars that will be discovered by MASCARA.
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