The GAPS Programme at TNG

Context. The existence of hot Jupiters is still not well understood. Two main channels are thought to be responsible for their current location: a smooth planet migration through the protoplanetary disk or the circularization of an initial highly eccentric orbit by tidal dissipation leading to a strong decrease in the semimajor axis. Different formation scenarios result in different observable effects, such as orbital parameters (obliquity and eccentricity) or frequency of planets at different stellar ages. Aims. In the context of the GAPS Young Objects project, we are carrying out a radial velocity survey with the aim of searching and characterizing young hot-Jupiter planets. Our purpose is to put constraints on evolutionary models and establish statistical properties, such as the frequency of these planets from a homogeneous sample. Methods. Since young stars are in general magnetically very active, we performed multi-band (visible and near-infrared) spectroscopy with simultaneous GIANO-B + HARPS-N (GIARPS) observing mode at TNG. This helps in dealing with stellar activity and distinguishing the nature of radial velocity variations: stellar activity will introduce a wavelength-dependent radial velocity amplitude, whereas a Keplerian signal is achromatic. As a pilot study, we present here the cases of two known hot Jupiters orbiting young stars: HD 285507 b and AD Leo b. Results. Our analysis of simultaneous high-precision GIARPS spectroscopic data confirms the Keplerian nature of the variation in the HD 285507 radial velocities and refines the orbital parameters of the hot Jupiter, obtaining an eccentricity consistent with a circular orbit. Instead, our analysis does not confirm the signal previously attributed to a planet orbiting AD Leo. This demonstrates the power of the multi-band spectroscopic technique when observing active stars.

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Multi-band high resolution spectroscopy rules out the hot Jupiter BD+20 1790b

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732350 ◽

2018 ◽

Vol 613 ◽

pp. A50 ◽

Cited By ~ 12

Author(s):

I. Carleo ◽

S. Benatti ◽

A. F. Lanza ◽

R. Gratton ◽

R. Claudi ◽

...

Keyword(s):

Radial Velocity ◽

Hot Spots ◽

Near Infrared ◽

High Resolution Spectroscopy ◽

Velocity Measurements ◽

Stellar Activity ◽

Multi Wavelength ◽

First Time ◽

Multi Band

Context. Stellar activity is currently challenging the detection of young planets via the radial velocity (RV) technique. Aims. We attempt to definitively discriminate the nature of the RV variations for the young active K5 star BD+20 1790, for which visible (VIS) RV measurements show divergent results on the existence of a substellar companion. Methods. We compare VIS data with high precision RVs in the near-infrared (NIR) range by using the GIANO–B and IGRINS spectrographs. In addition, we present for the first time simultaneous VIS-NIR observations obtained with GIARPS (GIANO–B and HARPS–N) at Telescopio Nazionale Galileo (TNG). Orbital RVs are achromatic, so the RV amplitude does not change at different wavelengths, while stellar activity induces wavelength-dependent RV variations, which are significantly reduced in the NIR range with respect to the VIS. Results. The NIR radial velocity measurements from GIANO–B and IGRINS show an average amplitude of about one quarter with respect to previously published VIS data, as expected when the RV jitter is due to stellar activity. Coeval multi-band photometry surprisingly shows larger amplitudes in the NIR range, explainable with a mixture of cool and hot spots in the same active region. Conclusions. In this work, the claimed massive planet around BD+20 1790 is ruled out by our data. We exploited the crucial role of multi-wavelength spectroscopy when observing young active stars: thanks to facilities like GIARPS that provide simultaneous observations, this method can reach its maximum potential.

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Early science with SPIRou: near-infrared radial velocity and spectropolarimetry of the planet-hosting star HD 189733

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038108 ◽

2020 ◽

Vol 642 ◽

pp. A72 ◽

Cited By ~ 1

Author(s):

C. Moutou ◽

S. Dalal ◽

J.-F. Donati ◽

E. Martioli ◽

C. P. Folsom ◽

...

Keyword(s):

Magnetic Flux ◽

Radial Velocity ◽

Large Scale ◽

Near Infrared ◽

Field Studies ◽

High Spectral Resolution ◽

Planetary Orbit ◽

Dominant Factor ◽

Stellar Activity ◽

Orbital Parameters

SPIRou is the newest spectropolarimeter and high-precision velocimeter that has recently been installed at the Canada-France-Hawaii Telescope on Maunakea, Hawaii. It operates in the near-infrared and simultaneously covers the 0.98–2.35 μm domain at high spectral resolution. SPIRou is optimized for exoplanet search and characterization with the radial-velocity technique, and for polarization measurements in stellar lines and subsequent magnetic field studies. The host of the transiting hot Jupiter HD 189733 b has been observed during early science runs. We present the first near-infrared spectropolarimetric observations of the planet-hosting star as well as the stellar radial velocities as measured by SPIRou throughout the planetary orbit and two transit sequences. The planetary orbit and Rossiter-McLaughlin anomaly are both investigated and modeled. The orbital parameters and obliquity are all compatible with the values found in the optical. The obtained radial-velocity precision is compatible with about twice the photon-noise estimates for a K2 star under these conditions. The additional scatter around the orbit, of about 8 m s−1, agrees with previous results that showed that the activity-induced scatter is the dominant factor. We analyzed the polarimetric signal, Zeeman broadening, and chromospheric activity tracers such as the 1083nm HeI and the 1282nm Paβ lines to investigate stellar activity. First estimates of the average unsigned magnetic flux from the Zeeman broadening of the FeI lines give a magnetic flux of 290 ± 58 G, and the large-scale longitudinal field shows typical values of a few Gauss. These observations illustrate the potential of SPIRou for exoplanet characterization and magnetic and stellar activity studies.

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A hot Saturn on an eccentric orbit around the giant star K2-132

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731478 ◽

2018 ◽

Vol 613 ◽

pp. A76 ◽

Cited By ~ 6

Author(s):

M. I. Jones ◽

R. Brahm ◽

N. Espinoza ◽

A. Jordán ◽

F. Rojas ◽

...

Keyword(s):

Radial Velocity ◽

Semimajor Axis ◽

Physical Parameters ◽

Giant Star ◽

Orbital Parameters ◽

Hot Jupiters ◽

Giant Stars ◽

Short Period ◽

Interesting Object ◽

Solar Type

Although the majority of radial velocity detected planets have been found orbiting solar-type stars, a fraction of them have been discovered around giant stars. These planetary systems have revealed different orbital properties when compared to solar-type star companions. In particular, radial velocity surveys have shown that there is a lack of giant planets in close-in orbits around giant stars, in contrast to the known population of hot Jupiters orbiting solar-type stars. It has been theorized that the reason for this distinctive feature in the semimajor axis distribution is the result of the stellar evolution and/or that it is due to the effect of a different formation/evolution scenario for planets around intermediate-mass stars. However, in the past few years a handful of transiting short-period planets (P ≲ 10 days) have been found around giant stars, thanks to the high-precision photometric data obtained initially by the Kepler mission, and later by its two-wheel extension K2. These new discoveries have allowed us for the first time to study the orbital properties and physical parameters of these intriguing and elusive substellar companions. In this paper we report on an independent discovery of a transiting planet in field 10 of the K2 mission, also reported recently by Grunblatt et al. (2017, AJ, 154, 254). The host star has recently evolved to the giant phase, and has the following atmospheric parameters: Teff = 4878 ± 70 K, log g = 3.289 ± 0.004, and [Fe/H] = −0.11 ± 0.05 dex. The main orbital parameters of K2-132 b, obtained with all the available data for the system are: P = 9.1708 ± 0.0025 d, e = 0.290 ± 0.049, Mp = 0.495 ± 0.007 MJ and Rp = 1.089 ± 0.006 RJ. This is the fifth known planet orbiting any giant star with a < 0.1, and the most eccentric one among them, making K2-132 b a very interesting object.

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Tidally induced stellar oscillations: converting modelled oscillations excited by hot Jupiters into observables

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3394 ◽

2020 ◽

Vol 500 (2) ◽

pp. 2711-2731

Author(s):

Andrew Bunting ◽

Caroline Terquem

Keyword(s):

Radial Velocity ◽

Orbital Period ◽

Planetary Systems ◽

Velocity Signal ◽

Convective Flux ◽

Hot Jupiters ◽

Stellar Oscillations ◽

Orbital Periods ◽

Hot Jupiter

ABSTRACT We calculate the conversion from non-adiabatic, non-radial oscillations tidally induced by a hot Jupiter on a star to observable spectroscopic and photometric signals. Models with both frozen convection and an approximation for a perturbation to the convective flux are discussed. Observables are calculated for some real planetary systems to give specific predictions. The photometric signal is predicted to be proportional to the inverse square of the orbital period, P−2, as in the equilibrium tide approximation. However, the radial velocity signal is predicted to be proportional to P−1, and is therefore much larger at long orbital periods than the signal corresponding to the equilibrium tide approximation, which is proportional to P−3. The prospects for detecting these oscillations and the implications for the detection and characterization of planets are discussed.

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Dynamical Study of the Exoplanet Host Binary System HD 106515

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2016.59 ◽

2017 ◽

Vol 34 ◽

Cited By ~ 2

Author(s):

F. M. Rica ◽

R. Barrena ◽

J. A. Henríquez ◽

F. M. Pérez ◽

P. Vargas

Keyword(s):

Radial Velocity ◽

Proper Motion ◽

Binary Star ◽

Semimajor Axis ◽

Numerical Code ◽

Dynamical Study ◽

Orbital Parameters ◽

Instantaneous Position ◽

Dynamical Parameters ◽

Binary Star System

AbstractHD 106515 AB (STF1619 AB) is a high common proper motion and common radial velocity binary star system composed of two G-type bright stars located at 35 pc and separated by about 7 arcsec. This system was observed by theHipparcossatellite with a precision in distance and proper motion of 3 and 2%, respectively. The system includes a circumprimary planet of nearly 10 Jupiter masses and a semimajor axis of 4.59 AU, discovered using the radial velocity method. The observational arc of 21° shows a small curvature that evidences HD 106515 AB is a gravitationally bound system. This work determines the dynamical parameters for this system which reinforce the bound status of both stellar components. We determine orbital solutions from instantaneous position and velocity vectors. In addition, we provide a very preliminary orbital solution and a distribution of the orbital parameters, obtained from the line of sight (z). Our results show that HD 106515 AB presents an orbital period of about 4 800 years, a semimajor axis of 345 AU and an eccentricity of about 0.42. Finally, we use an N-body numerical code to perform simulations and reproduce the longer term octupole perturbations on the inner orbit.

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Secondary eclipse of the hot Jupiter WASP-121b at 2 μm

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834325 ◽

2019 ◽

Vol 625 ◽

pp. A80 ◽

Cited By ~ 8

Author(s):

Géza Kovács ◽

Tamás Kovács

Keyword(s):

Near Infrared ◽

Infrared Emission ◽

Current Data ◽

Emission Analysis ◽

Hot Jupiters ◽

Occultation Data ◽

The One ◽

Near Infrared Emission ◽

Absorption Features ◽

Hot Jupiter

Ground-based observations of the secondary eclipse in the 2MASS K band are presented for the hot Jupiter WASP-121b. These are the first occultation observations of an extrasolar planet that were carried out with an instrument attached to a 1 m class telescope (the SMARTS 1.3 m). We find a highly significant eclipse depth of (0.228 ± 0.023)%. Together with other planet atmosphere measurements, including the Hubble Space Telescope near-infrared emission spectrum, current data support more involved atmosphere models with species producing emission and absorption features, rather than simple smooth blackbody emission. Analysis of the time difference between the primary and secondary eclipses and the durations of these events yields an eccentricity of e = 0.0207 ± 0.0153, which is consistent with the earlier estimates of low or zero eccentricity, but with a smaller error. Comparing the observed occultation depth in the K band with the one derived under the assumption of zero Bond albedo and full heat redistribution, we find that WASP-121b has a deeper observed occultation depth than predicted. Together with the sample of 31 systems with K-band occultation data, this observation lends further support to the idea of inefficient heat transport between the day and night sides for most of the hot Jupiters.

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Constraining the properties of HD 206893 B

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935044 ◽

2019 ◽

Vol 627 ◽

pp. L9 ◽

Cited By ~ 8

Author(s):

A. Grandjean ◽

A.-M. Lagrange ◽

H. Beust ◽

L. Rodet ◽

J. Milli ◽

...

Keyword(s):

Radial Velocity ◽

Semimajor Axis ◽

High Contrast ◽

Brown Dwarf ◽

Contrast Imaging ◽

Dynamical Mass ◽

Orbital Parameters ◽

High Contrast Imaging ◽

Very Large Telescope ◽

Astrometric Data

Context. High contrast imaging enables the determination of orbital parameters for substellar companions (planets, brown dwarfs) from the observed relative astrometry and the estimation of model and age-dependent masses from their observed magnitudes or spectra. Combining astrometric positions with radial velocity gives direct constraints on the orbit and on the dynamical masses of companions. A brown dwarf was discovered with the VLT/SPHERE instrument at the Very Large Telescope (VLT) in 2017, which orbits at ∼11 au around HD 206893. Its mass was estimated between 12 and 50 MJ from evolutionary models and its photometry. However, given the significant uncertainty on the age of the system and the peculiar spectrophotometric properties of the companion, this mass is not well constrained. Aims. We aim at constraining the orbit and dynamical mass of HD 206893 B. Methods. We combined radial velocity data obtained with HARPS spectra and astrometric data obtained with the high contrast imaging VLT/SPHERE and VLT/NaCo instruments, with a time baseline less than three years. We then combined those data with astrometry data obtained by HIPPARCOS and Gaia with a time baseline of 24 yr. We used a Markov chain Monte Carlo approach to estimate the orbital parameters and dynamical mass of the brown dwarf from those data. Results. We infer a period between 21 and 33 yr and an inclination in the range 20−41° from pole-on from HD 206893 B relative astrometry. The RV data show a significant RV drift over 1.6 yr. We show that HD 206893 B cannot be the source of this observed RV drift as it would lead to a dynamical mass inconsistent with its photometry and spectra and with HIPPARCOS and Gaia data. An additional inner (semimajor axis in the range 1.4–2.6 au) and massive (∼15 MJ) companion is needed to explain the RV drift, which is compatible with the available astrometric data of the star, as well as with the VLT/SPHERE and VLT/NaCo nondetection.

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Water vapor detection in the transmission spectra of HD 209458 b with the CARMENES NIR channel

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936084 ◽

2019 ◽

Vol 630 ◽

pp. A53 ◽

Cited By ~ 13

Author(s):

A. Sánchez-López ◽

F. J. Alonso-Floriano ◽

M. López-Puertas ◽

I. A. G. Snellen ◽

B. Funke ◽

...

Keyword(s):

Water Vapor ◽

Near Infrared ◽

Signal To Noise Ratio ◽

Principal Component ◽

Large Change ◽

Large Error ◽

Water Vapor Absorption ◽

Stable Conditions ◽

Multi Band ◽

Hot Jupiter

Aims. We aim at detecting water vapor in the atmosphere of the hot Jupiter HD 209458 b and perform a multi-band study in the near infrared with CARMENES. Methods. The water vapor absorption lines from the atmosphere of the planet are Doppler-shifted due to the large change in its radial velocity during transit. This shift is of the order of tens of km s−1, whilst the Earth’s telluric and the stellar lines can be considered quasi-static. We took advantage of this shift to remove the telluric and stellar lines using SYSREM, which performs a principal component analysis including proper error propagation. The residual spectra contain the signal from thousands of planetary molecular lines well below the noise level. We retrieve the information from those lines by cross-correlating the residual spectra with models of the atmospheric absorption of the planet. Results. We find a cross-correlation signal with a signal-to-noise ratio (S/N) of 6.4, revealing H2O in HD 209458 b. We obtain a net blueshift of the signal of –5.2 −1.3+2.6 km s−1 that, despite the large error bars, is a firm indication of day- to night-side winds at the terminator of this hot Jupiter. Additionally, we performed a multi-band study for the detection of H2O individually from the three near infrared bands covered by CARMENES. We detect H2O from its 0.96–1.06 μm band with a S/N of 5.8, and also find hints of a detection from the 1.06–1.26 μm band, with a low S/N of 2.8. No clear planetary signal is found from the 1.26–1.62 μm band. Conclusions. Our significant H2O signal at 0.96–1.06 μm in HD 209458 b represents the first detection of H2O from this band individually, the bluest one to date. The unfavorable observational conditions might be the reason for the inconclusive detection from the stronger 1.15 and 1.4 μm bands. H2O is detected from the 0.96–1.06 μm band in HD 209458 b, but hardly in HD 189733 b, which supports a stronger aerosol extinction in the latter, in line with previous studies. Future data gathered at more stable conditions and with larger S/N at both optical and near-infrared wavelengths could help to characterize the presence of aerosols in HD 209458 b and other planets.

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Tidal effects on stellar activity

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317004045 ◽

2016 ◽

Vol 12 (S328) ◽

pp. 308-314

Author(s):

K. Poppenhaeger

Keyword(s):

Orbital Period ◽

Binary Systems ◽

Semimajor Axis ◽

Rotation Period ◽

Magnetic Activity ◽

Stellar Rotation ◽

Stellar Activity ◽

Tidal Interaction ◽

Hot Jupiters ◽

Orbital Periods

AbstractThe architecture of many exoplanetary systems is different from the solar system, with exoplanets being in close orbits around their host stars and having orbital periods of only a few days. We can expect interactions between the star and the exoplanet for such systems that are similar to the tidal interactions observed in close stellar binary systems. For the exoplanet, tidal interaction can lead to circularization of its orbit and the synchronization of its rotational and orbital period. For the host star, it has long been speculated if significant angular momentum transfer can take place between the planetary orbit and the stellar rotation. In the case of the Earth-Moon system, such tidal interaction has led to an increasing distance between Earth and Moon. For stars with Hot Jupiters, where the orbital period of the exoplanet is typically shorter than the stellar rotation period, one expects a decreasing semimajor axis for the planet and enhanced stellar rotation, leading to increased stellar activity. Also excess turbulence in the stellar convective zone due to rising and subsiding tidal bulges may change the magnetic activity we observe for the host star. I will review recent observational results on stellar activity and tidal interaction in the presence of close-in exoplanets, and discuss the effects of enhanced stellar activity on the exoplanets in such systems.

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Following the TraCS of exoplanets with Pan-Planets: Wendelstein-1b and Wendelstein-2b

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037715 ◽

2020 ◽

Vol 639 ◽

pp. A130

Author(s):

C. Obermeier ◽

J. Steuer ◽

H. Kellermann ◽

R. P. Saglia ◽

Th. Henning ◽

...

Keyword(s):

Surface Temperature ◽

Radial Velocity ◽

Thermal Emission ◽

Dwarf Star ◽

Statistical Characterization ◽

Hot Jupiters ◽

Eclipse Observations ◽

Short Period ◽

Hot Jupiter

Hot Jupiters seem to get rarer with decreasing stellar mass. The goal of the Pan-Planets transit survey was the detection of such planets and a statistical characterization of their frequency. Here, we announce the discovery and validation of two planets found in that survey, Wendelstein-1b and Wendelstein-2b, which are two short-period hot Jupiters that orbit late K host stars. We validated them both by the traditional method of radial velocity measurements with the HIgh Resolution Echelle Spectrometer and the Habitable-zone Planet Finder instruments and then by their Transit Color Signature (TraCS). We observed the targets in the wavelength range of 4000−24 000 Å and performed a simultaneous multiband transit fit and additionally determined their thermal emission via secondary eclipse observations. Wendelstein-1b is a hot Jupiter with a radius of 1.0314−0.0061+0.0061 RJ and mass of 0.592−0.129+0.0165 MJ, orbiting a K7V dwarf star at a period of 2.66 d, and has an estimated surface temperature of about 1727−90+78 K. Wendelstein-2b is a hot Jupiter with a radius of 1.1592−0.0210+0.0204 RJ and a mass of 0.731−0.311+0.0541 MJ, orbiting a K6V dwarf star at a period of 1.75 d, and has an estimated surface temperature of about 1852−140+120 K. With this, we demonstrate that multiband photometry is an effective way of validating transiting exoplanets, in particular for fainter targets since radial velocity follow-up becomes more and more costly for those targets.

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