Tracking Advanced Planetary Systems (TAPAS) with HARPS-N

Context. We present the latest results of our search for planets with HARPS-N at the 3.6 m Telescopio Nazionale Galileo under the Tracking Advanced Planetary Systems project: an in-depth study of the 15 most Li abundant giants from the PennState – Toruń Planet Search sample. Aims. Our goals are first, to obtain radial velocities of the most Li-rich giants we identified in our sample to search for possible low-mass substellar companions, and second, to perform an extended spectral analysis to define the evolutionary status of these stars. Methods. This work is based on high-resolution spectra obtained with the Hobby-Eberly Telescope and its High Resolution Spectrograph, and with the HARPS-N spectrograph at the Telescopio Nazionale Galileo. Two stars, HD 181368 and HD 188214, were also observed with UVES at the VLT to determine beryllium abundances. Results. We report i) the discovery of two new planetary systems around the Li-rich giant stars: HD 238914 and TYC 3318-01333-1 (a binary system); ii) reveal a binary Li-rich giant, HD 181368; iii) although our current phase coverage is not complete, we suggest the presence of planetary mass companions around TYC 3663-01966-1 and TYC 3105-00152-1; iv) we confirm the previous result for BD+48 740 and present updated orbital parameters, and v) we find a lack of a relation between the Li enhancement and the Be abundance for the stars HD 181368 and HD 188214, for which we acquired blue spectra. Conclusions. We found seven stars with stellar or potential planetary companions among the 15 Li-rich giant stars. The binary star frequency of the Li-rich giants in our sample appears to be normal, but the planet frequency is twice that of the general sample, which suggests a possible connection between hosting a companion and enhanced Li abundance in giant stars. We also found most of the companions orbits to be highly eccentric.

Download Full-text

Twin stars as tracers of binary evolution in the Kepler era

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab343 ◽

2021 ◽

Author(s):

Sara Bulut ◽

Baris Hoyman ◽

Ahmet Dervisoglu ◽

Orkun Özdarcan ◽

Ömür Cakilrli

Keyword(s):

High Resolution ◽

Internal Structure ◽

Spectroscopic Analysis ◽

Independent Method ◽

Eclipsing Binaries ◽

Physical Parameters ◽

Evolutionary Status ◽

Mass Ratio ◽

Orbital Parameters ◽

Binary Evolution

Abstract We present results of the combined photometric and spectroscopic analysis of four systems, which are eclipsing binaries with a twin–component (mass ratio q ≃ 1). These are exceptional tools to provide information for probing the internal structure of stars. None of the systems were previously recognized as twin binaries. We used a number of high–resolution optical spectra to calculate the radial velocities and later combined them with photometry to derive orbital parameters. Temperatures and metallicities of systems were estimated from high-resolution spectra. For each binary, we obtained a full set of orbital and physical parameters, reaching precision below 3 per cent in masses and radii for whole pairs. By comparing our results with PARSEC and MIST isochrones, we assess the distance, age and evolutionary status of the researched objects. The primary and/or secondary stars of EPIC 216075815 and EPIC 202843107 are one of the cases where asteroseismic parameters of δ Sct and γ Dor pulsators were confirmed by an independent method and rare examples of the twin–eclipsing binaries, therefore the following analyses and results concern the pulsating nature of the components.

Download Full-text

Lithium Abundances in Fast Rotating Bright Giant Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900195671 ◽

2004 ◽

Vol 215 ◽

pp. 246-247

Author(s):

J.D. do Nascimento ◽

A. Lèbre ◽

R. Konstantinova-Antova ◽

J. R. de Medeiros

Keyword(s):

High Resolution ◽

Class Ii ◽

Evolutionary Status ◽

Intermediate Mass ◽

Luminosity Class ◽

Spectroscopic Observations ◽

Giant Stars ◽

Resonance Doublet ◽

Li Content ◽

Fast Rotating

We present the results of high resolution spectroscopic observations of Li I resonance doublet at λ 6707.8 Å for fast rotating single stars of luminosity class II and Ib. We present a discussion on the link between rotation and Li content in intermediate mass giant stars, with emphasis on their evolutionary status. At least one of the observed stars, HD 232862, a G8II with an unusual vsini of 20 km/s, present a Li-rich behavior.

Download Full-text

EFFECTS OF CHAOTIC “CLEARING” IN PLANETARY SYSTEMS

Journal of Oceanological Research ◽

10.29006/1564-2291.jor-2019.47(1).41 ◽

2019 ◽

Vol 47 (1) ◽

pp. 132-134

Author(s):

I.I. Shevchenko

Keyword(s):

Binary Star ◽

Kuiper Belt ◽

Planetary Systems ◽

Cometary Nuclei ◽

Body Contact ◽

Mean Motion Resonances ◽

First Order ◽

Contact Binary ◽

Low Mass ◽

Orbital Resonances

The main types of chaotic clearing effects in planetary systems are considered. The clearing consists in the formation of orbital zones free from low-mass bodies (planetesimals, asteroids, particles, fragments), due to the dynamical chaotization in the presence of perturbations. The effects include: (1) the coorbital clearing – the formation of a ring-like clearance in the planetesimal disk due to the accumulation and overlap of «particle–planet» orbital (mean-motion) resonances of the first order in the radial neighborhood of a planetary orbit (Wisdom, 1980; Demidova, Shevchenko, 2016); (2) the circumbinary clearing – the formation of a whole circular clearance in the planetesimal disk around a binary star due to the overlap of «particle–binary» integer orbital resonances accumulating to the separatrix corresponding to the parabolic motion (Shevchenko, 2015); (3) the circumnuclear clearing – the formation of a whole circular clearance in the cloud of particles and fragments around a rotating irregularly-shaped body (contact binary, such as cometary nuclei, many objects in the Kuiper belt, and asteroids) due to the overlap of «particle – contact binary» integer orbital resonances, accumulating to the separatrix corresponding to the parabolic motion (Lages et al., 2017, 2018). Particular attention is paid to the latter case, as identified just recently. The research was supported by the RAS Presidium Program «Nonlinear dynamics: fundamental problems and applications».

Download Full-text

The CARMENES search for exoplanets around M dwarfs

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935534 ◽

2019 ◽

Vol 627 ◽

pp. A116 ◽

Cited By ~ 4

Author(s):

S. Lalitha ◽

D. Baroch ◽

J. C. Morales ◽

V. M. Passegger ◽

F. F. Bauer ◽

...

Keyword(s):

Near Infrared ◽

Correlated Noise ◽

Stellar Rotation ◽

M Dwarfs ◽

Stellar Activity ◽

Orbital Parameters ◽

Rotation Periods ◽

Planetary Mass ◽

Low Mass ◽

Orbital Periods

Although M dwarfs are known for high levels of stellar activity, they are ideal targets for the search of low-mass exoplanets with the radial velocity (RV) method. We report the discovery of a planetary-mass companion around LSPM J2116+0234 (M3.0 V) and confirm the existence of a planet orbiting GJ 686 (BD+18 3421; M1.0 V). The discovery of the planet around LSPM J2116+0234 is based on CARMENES RV observations in the visual and near-infrared channels. We confirm the planet orbiting around GJ 686 by analyzing the RV data spanning over two decades of observationsfrom CARMENES VIS, HARPS-N, HARPS, and HIRES. We find planetary signals at 14.44 and 15.53 d in the RV data for LSPM J2116+0234 and GJ 686, respectively. Additionally, the RV, photometric time series, and various spectroscopic indicators show hints of variations of 42 d for LSPM J2116+0234 and 37 d for GJ 686, which we attribute to the stellar rotation periods. The orbital parameters of the planets are modeled with Keplerian fits together with correlated noise from the stellar activity. A mini-Neptune with a minimum mass of 11.8 M⊕ orbits LSPM J2116+0234 producing a RV semi-amplitude of 6.19 m s−1, while a super-Earth of mass 6.6 M⊕ orbits GJ 686 and produces a RV semi-amplitude of 3.0 m s−1. Both LSPM J2116+0234 and GJ 686 have planetary companions populating the regime of exoplanets with masses lower than 15 M⊕ and orbital periods <20 d.

Download Full-text

MACHO observations of LMC red giants: Mira and semi-regular pulsators, and contact and semi-detached binaries

Symposium - International Astronomical Union ◽

10.1017/s007418090020301x ◽

1999 ◽

Vol 191 ◽

pp. 151-158 ◽

Cited By ~ 15

Author(s):

P.R. Wood ◽

C. Alcock ◽

R.A. Allsman ◽

D. Alves ◽

T.S. Axelrod ◽

...

Keyword(s):

Binary Star ◽

Theoretical Models ◽

Light Curves ◽

Red Giants ◽

Giant Stars ◽

Intermediate Mass Stars ◽

Contact Binaries ◽

Low Mass ◽

Red Giant ◽

Detached Binaries

The MACHO data base has been used to examine light curves of all red giant stars brighter than Mbol ∼ −2 in a 0.5° × 0.5° area of the LMC bar. Periods, often multiple, have been searched for in all stars found to be variable. Five distinct period-luminosity sequences have been found on the low mass (M ≲ 2.25M⊙) giant branch. Comparison of observed periods, luminosities and period ratios with theoretical models identifies Miras unambiguously as radial fundamental mode pulsators, while semi-regular variables can be pulsating in the 1st, 2nd or 3rd overtone, or even the fundamental. All these variables lie on just 3 of the 5 distinct sequences, and they all appear to be on the AGB.The fourth sequence contains red giants on the first giant branch (FGB) or at the red end of the core-helium burning loops of intermediate mass stars (M ≳ 2.25M⊙). The light curves of these stars strongly suggest that they are contact binaries, and they make up ∼0.5% of stars within 1 mag. of the FGB tip. Stars on the fifth sequence show semi-regular, eclipse-like light curves. The light curves and periods of these stars suggest that they are in semi-detached binaries, transfering mass to an invisible companion via a stellar wind or Roche lobe overflow. They make up ∼25% of AGB stars. If the existence of these red giant contact and semi-detached binaries is confirmed, then extant theories of binary star evolution will require substantial modification.

Download Full-text

Exploring the realm of scaled solar system analogues with HARPS

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832791 ◽

2018 ◽

Vol 615 ◽

pp. A175 ◽

Cited By ~ 9

Author(s):

D. Barbato ◽

A. Sozzetti ◽

S. Desidera ◽

M. Damasso ◽

A. S. Bonomo ◽

...

Keyword(s):

Solar System ◽

High Precision ◽

Giant Planet ◽

Planetary Systems ◽

Giant Planets ◽

Orbital Parameters ◽

Long Period ◽

Link Type ◽

Low Mass ◽

High Cadence

Context. The assessment of the frequency of planetary systems reproducing the solar system’s architecture is still an open problem in exoplanetary science. Detailed study of multiplicity and architecture is generally hampered by limitations in quality, temporal extension and observing strategy, causing difficulties in detecting low-mass inner planets in the presence of outer giant planets. Aims. We present the results of high-cadence and high-precision HARPS observations on 20 solar-type stars known to host a single long-period giant planet in order to search for additional inner companions and estimate the occurence rate fp of scaled solar system analogues – in other words, systems featuring lower-mass inner planets in the presence of long-period giant planets. Methods. We carried out combined fits of our HARPS data with literature radial velocities using differential evolution MCMC to refine the literature orbital solutions and search for additional inner planets. We then derived the survey detection limits to provide preliminary estimates of fp. Results. We generally find better constrained orbital parameters for the known planets than those found in the literature; significant updates can be especially appreciated on half of the selected planetary systems. While no additional inner planet is detected, we find evidence for previously unreported long-period massive companions in systems HD 50499 and HD 73267. We finally estimate the frequency of inner low mass (10–30 M⊕) planets in the presence of outer giant planets as fp < 9.84% for P < 150 days. Conclusions. Our preliminary estimate of fp is significantly lower than the literature values for similarly defined mass and period ranges; the lack of inner candidate planets found in our sample can also be seen as evidence corroborating the inwards-migration formation model for super-Earths and mini-Neptunes. Our results also underline the need for high-cadence and high-precision followup observations as the key to precisely determine the occurence of solar system analogues.

Download Full-text

FK Comae and the Evolution of Close Binaries

Symposium - International Astronomical Union ◽

10.1017/s0074180900122582 ◽

1992 ◽

Vol 151 ◽

pp. 403-406

Author(s):

David P. Huenemoerder ◽

Lawrence W. Ramsey ◽

Derek L. Buzasi ◽

Harold L. Nations

Keyword(s):

Binary Star ◽

Magnetic Activity ◽

Close Binary ◽

Close Binaries ◽

Evolutionary Status ◽

Dynamo Theory ◽

Cool Stars ◽

Depth Study ◽

Important Object ◽

Close Binary Star

FK Com is an enigma among active cool stars. A rotationally driven magnetic dynamo is an explanation for activity. Youth and binarity are two causes of rapid rotation, but FK Com is old, single, and rotating near breakup. Much studied optical and ultraviolet data have not revealed the cause of its unusual activity. It is an important object in a more complete understanding of close binary star evolution and of the dynamo theory of magnetic activity. In 1989, we executed a coordinated ultraviolet and intensive optical spectroscopic and photometric campaign to better elucidate its characteristics. Data relevant to its evolutionary status, namely its radial velocity variations, will be discussed here, while an in depth study of the chromospheric activity will be deferred to a more detailed publication.

Download Full-text

Giant planets around AF and M stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313007898 ◽

2013 ◽

Vol 8 (S299) ◽

pp. 64-65

Author(s):

Julien Rameau ◽

Gaël Chauvin ◽

Anne-Marie Lagrange ◽

Philippe Delorme ◽

Justine Lannier

Keyword(s):

Giant Planets ◽

Early Type ◽

Late Type ◽

M Dwarfs ◽

Low Mass Stars ◽

Planetary Mass ◽

Nearby Stars ◽

Low Mass ◽

M Stars ◽

The One

AbstractWe present the results of two three-year surveys of young and nearby stars to search for wide orbit giant planets. On the one hand, we focus on early-type and massive, namely β Pictoris analogs. On the other hand, we observe late type and very low mass stars, i.e., M dwarfs. We report individual detections of new planetary mass objects. According to our deep detection performances, we derive the observed frequency of giant planets between these two classes of parent stars. We find frequency between 6 to 12% but we are not able to assess a/no correlation with the host-mass.

Download Full-text