U Geminorum: a Test Case for Orbital Parameters Determination

AbstractHigh-resolution spectroscopy of U Gem was obtained during quiescence. We did not find a hot spot or gas stream around the outer boundaries of the accretion disk. Instead, we detected a strong narrow emission near the location of the secondary star. We measured the radial velocity curve from the wings of the double-peaked Hα emission line, and obtained a semi-amplitude value in excellent agreement with the ultraviolet results by Long & Gilliland (1999). We present also a new method to obtain K2, which enhances the detection of absorption or emission features arising in the late-type companion. Our results are compared with published values derived from the near-infrared NaI line doublet. From a comparison of the TiO band with those of late type M stars, we find that a best fit is obtained for a M6 V star, contributing 5% of the total light at that spectral region. Assuming that the radial velocity semi-amplitudes reflect accurately the motion of the binary components, then from our results: Kem = 108 ± 2 km s−1; Kabs = 310 ± 5 km s−1, and using the inclination angle by Zhang & Robinson (1987); i = 69°.7 ± 0.7, the system parameters become: MWD = 1.20 ± 0.05 M⊙; MRD = 0.42 ± 0.04 M⊙; and a = 1.55 ± 0.02 R⊙. Based on the separation of the double emission peaks, we calculate an outer disk radius of Rout/a ∼ 0.63, close to the distance of the inner Lagrangian point L1/a ∼ 0.63. Therefore we suggest that, at the time of observations, the accretion disk was filling the Roche-Lobe of the primary, and that the matter leaving the L1 point was colliding with the disc directly, producing the hot spot at this location. Specific details not included in the printed version can be found in the Electronic Poster (EP).

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On the synergy between Ariel and ground-based high-resolution spectroscopy

Experimental Astronomy ◽

10.1007/s10686-021-09824-7 ◽

2022 ◽

Author(s):

Gloria Guilluy ◽

Alessandro Sozzetti ◽

Paolo Giacobbe ◽

Aldo S. Bonomo ◽

Giuseppina Micela

Keyword(s):

High Resolution ◽

Near Infrared ◽

Major Axis ◽

High Resolution Spectroscopy ◽

Correlation Technique ◽

Temperature Structure ◽

Low Resolution ◽

Semi Major Axis ◽

Species Discovery ◽

Orbital Parameters

AbstractSince the first discovery of an extra-solar planet around a main-sequence star, in 1995, the number of detected exoplanets has increased enormously. Over the past two decades, observational instruments (both onboard and on ground-based facilities) have revealed an astonishing diversity in planetary physical features (i. e. mass and radius), and orbital parameters (e.g. period, semi-major axis, inclination). Exoplanetary atmospheres provide direct clues to understand the origin of these differences through their observable spectral imprints. In the near future, upcoming ground and space-based telescopes will shift the focus of exoplanetary science from an era of “species discovery” to one of “atmospheric characterization”. In this context, the Atmospheric Remote-sensing Infrared Exoplanet Large (Ariel) survey, will play a key role. As it is designed to observe and characterize a large and diverse sample of exoplanets, Ariel will provide constraints on a wide gamut of atmospheric properties allowing us to extract much more information than has been possible so far (e.g. insights into the planetary formation and evolution processes). The low resolution spectra obtained with Ariel will probe layers different from those observed by ground-based high resolution spectroscopy, therefore the synergy between these two techniques offers a unique opportunity to understanding the physics of planetary atmospheres. In this paper, we set the basis for building up a framework to effectively utilise, at near-infrared wavelengths, high-resolution datasets (analyzed via the cross-correlation technique) with spectral retrieval analyses based on Ariel low-resolution spectroscopy. We show preliminary results, using a benchmark object, namely HD 209458 b, addressing the possibility of providing improved constraints on the temperature structure and molecular/atomic abundances.

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The GAPS Programme at TNG

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937369 ◽

2020 ◽

Vol 638 ◽

pp. A5 ◽

Cited By ~ 6

Author(s):

I. Carleo ◽

L. Malavolta ◽

A. F. Lanza ◽

M. Damasso ◽

S. Desidera ◽

...

Keyword(s):

Radial Velocity ◽

Near Infrared ◽

Semimajor Axis ◽

Young Stars ◽

Homogeneous Sample ◽

Stellar Activity ◽

Orbital Parameters ◽

Hot Jupiters ◽

Multi Band ◽

Hot Jupiter

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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The supergiant O + O binary system HD 166734: a new study

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317003313 ◽

2016 ◽

Vol 12 (S329) ◽

pp. 402-402 ◽

Cited By ~ 1

Author(s):

E. Gosset ◽

L. Mahy ◽

Y. Damerdji ◽

C. Nitschelm ◽

H. Sana ◽

...

Keyword(s):

Binary System ◽

Light Curve ◽

Radial Velocity ◽

Velocity Curve ◽

Physical Parameters ◽

Radial Velocity Curve ◽

X Ray ◽

Orbital Parameters

AbstractWe present here a modern study of the radial velocity curve and of the photometric light curve of the very interesting supergiant O7.5If + O9I(f) binary system HD 166734. The physical parameters of the stars and the orbital parameters are carefully determined. We also perform the analysis of the observed X-ray light curve of this colliding-wind binary.

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Discrepant Measurements of the Radial Velocities of SS Cygni: Solution to the Problem

International Astronomical Union Colloquium ◽

10.1017/s0252921100104713 ◽

1987 ◽

Vol 93 ◽

pp. 113-118

Author(s):

E.L. Robinson

Keyword(s):

Radial Velocity ◽

Accretion Disk ◽

White Dwarf ◽

Center Of Mass ◽

Velocity Curve ◽

Radial Velocities ◽

Radial Velocity Curve ◽

Dwarf Nova

AbstractWe show that the discrepancies among the various measurements of the radial velocity curve of the K5 V star in the dwarf nova SS Cyg have been caused by (1) poor choices of lines for measuring its velocity and (2) large distortions in its velocity caused by heating from the white dwarf and its accretion disk. The correct K velocity of the center of mass of the K5 V star is 158 ± 3 km s−1.

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Semidetached double-lined eclipsing binaries: Stellar parameters and rare classes

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3363 ◽

2019 ◽

Vol 491 (4) ◽

pp. 5489-5497 ◽

Cited By ~ 1

Author(s):

Oleg Yu Malkov

Keyword(s):

Radial Velocity ◽

Velocity Curve ◽

Eclipsing Binaries ◽

Physical Parameters ◽

Radial Velocity Curve ◽

Orbital Parameters ◽

Comprehensive List ◽

Use Of Data ◽

Rare Classes

ABSTRACT Semidetached eclipsing systems provide a unique opportunity to derive the basic properties of interacting binaries. The goal of this work is to collect and to make use of data on semidetached systems with available light and radial velocity curve solutions. I have compiled the most comprehensive list to date, of 119 semidetached double-lined eclipsing binaries, containing the orbital parameters and physical parameters of the components. I consider the classification of semidetached binaries and discuss gaps between various classes in the Hertzspung–Russell diagram. I list systems with component parameters that are inverted and briefly discuss their evolutionary state.

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59 Cygni: A Tilted ϕ Persei like System

International Astronomical Union Colloquium ◽

10.1017/s0252921100056566 ◽

2000 ◽

Vol 175 ◽

pp. 581-584 ◽

Cited By ~ 2

Author(s):

Th. Rivinius ◽

S. Štefl

Keyword(s):

Radial Velocity ◽

Compact Star ◽

Velocity Curve ◽

Similar Nature ◽

Radial Velocity Curve ◽

Orbital Parameters ◽

The One

AbstractThe binarity of 59 Cygni was confirmed and orbital parameters from the radial velocity curve of the primary derived. The observed emission variability resembles the one of ɸ Per in quite some detail, suggesting a similar nature of the companion: a hot, compact star.

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Pulsating chromosphere of classical Cepheids

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037795 ◽

2020 ◽

Vol 641 ◽

pp. A74

Author(s):

V. Hocdé ◽

N. Nardetto ◽

S. Borgniet ◽

E. Lagadec ◽

P. Kervella ◽

...

Keyword(s):

Radial Velocity ◽

Velocity Gradient ◽

Near Infrared ◽

High Resolution Spectroscopy ◽

Absorption Feature ◽

Circumstellar Envelope ◽

Dynamical Structure ◽

Ionized Gas ◽

Long Period ◽

Pulsation Cycle

Context. It has recently been shown that the infrared (IR) emission of Cepheids, constant over the pulsation cycle, might be due to a pulsating shell of ionized gas with a radius of about 15% of that of the star radius, which could be attributed to the chromospheric activity of Cepheids. Aims. The aim of this paper is to investigate the dynamical structure of the chromosphere of Cepheids along the pulsation cycle and to quantify its size. Methods. We present Hα and calcium near-infrared triplet (Ca IR) profile variations using high-resolution spectroscopy with the UVES spectrograph of a sample of 24 Cepheids with a good period coverage from ≈3 to 60 days. After a qualitative analysis of the spectral line profiles, we quantified the Van Hoof effect (velocity gradient between the Hα and Ca IR) as a function of the period of the Cepheids. We then used the Schwarzschild mechanism (a line doubling due to a shock wave) to quantify the size of the chromosphere. Results. We find a significant Van Hoof effect for Cepheids with a period larger than P = 10 days. In particular, Hα lines are delayed with a velocity gradient up to Δv ≈ 30 km s−1 compared to Ca IR. By studying the shocks, we find that the size of the chromosphere of long-period Cepheids is of at least ≈50% of the stellar radius, which is consistent at first order with the size of the shell made of ionized gas previously found from the analysis of IR excess. Last, for most of the long-period Cepheids in the sample, we report a motionless absorption feature in the Hα line that we attribute to a circumstellar envelope that surrounds the chromosphere. Conclusions. Analyzing the Ca IR lines of Cepheids is of importance to potentially unbias the period–luminosity relation from their IR excess, particularly in the context of forthcoming observations of radial velocity measurements from the Radial Velocity Spectrometer on board Gaia, which could be sensitive to their chromosphere.

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