Chromospherically Active Stars in the Rave Survey. Ii. Young Dwarfs in the Solar Neighborhood

Žerjal, M.; Zwitter, T.; Matijevič, G.; Grebel, E. K.; Kordopatis, G.; Munari, U.; Seabroke, G. M.; Steinmetz, Matthias; Wojno, Jennifer; Bienaymé, O.; Bland-Hawthorn, Joss; Conrad, C.; Freeman, K. C.; Gibson, Brad K.; Gilmore, G.; Kunder, Andrea; Navarro, Julio F.; Parker, Quentin A.; Reid, Warren A.; Siviero, A.; Watson, Fred; Wyse, Rosemary F. Ġ.

doi:10.3847/1538-4357/835/1/61

Cited by 25 publications

(7 citation statements)

References 64 publications

(74 reference statements)

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“…This result is in agreement with all the works that studied the evolution of the level of magnetic activity vs. age (see e.g. Žerjal et al 2017;Oláh et al 2016, and references therein)…”

Section: Oláh Et Al (2016) Investigated How Thesupporting

confidence: 93%

Activity cycles in members of young loose stellar associations

Distefano

Lanzafame

Lanza

et al. 2017

A&A

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Context. Magnetic cycles analogous to the solar one have been detected in tens of solar-like stars by analyzing long-term time-series of different magnetic activity indexes. The relationship between the cycle properties and global stellar parameters is not fully understood yet. One reason for this is the sparseness of the data. Aims. In the present paper we searched for activity cycles in a sample of 90 young solar-like stars with ages between 4 and 95 Myr with the aim to investigate the properties of activity cycles in this age range. Methods. We measured the length P cyc of a given cycle by analyzing the long-term time-series of three different activity indexes: the period of rotational modulation, the amplitude of the rotational modulation and the median magnitude in the V band. For each star, we computed also the global magnetic activity index that is proportional to the amplitude of the rotational modulation and can be regarded as a proxy of the mean level of the surface magnetic activity. Results. We detected activity cycles in 67 stars. Secondary cycles were also detected in 32 stars of the sample. The lack of correlation between P cyc and P rot and the position of our targets in the P cyc /P rot − Ro −1 diagram suggest that these stars belong to the so-called Transitional Branch and that the dynamo acting in these stars is different from the solar one and from that acting in the older Mt. Wilson stars. This statement is also supported by the analysis of the butterfly diagrams whose patterns are very different from those seen in the solar case. We computed the Spearman correlation coefficient r S between P cyc , and different stellar parameters. We found that P cyc in our sample is uncorrelated with all the investigated parameters. The index is positively correlated with the convective turn-over time-scale, the magnetic diffusivity time-scale τ diff , and the dynamo number D N , whereas it is anti-correlated with the effective temperature T eff , the photometric shear ∆Ω phot and the radius R C at which the convective zone is located. We investigated how P cyc and evolve with the stellar age. We found that P cyc is about constant and that decreases with the stellare age in the range 4-95 Myr. Finally we investigated the magnetic activity of the star AB Dor A by merging ASAS time-series with previous long-term photometric data. We estimated the length of the AB Dor A primary cycle as P cyc = 16.78 ± 2yr and we found also shorter secondary cycles with lengths of 400 d, 190 d and 90 d respectively.

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“…This result is in agreement with all the works that studied the evolution of the level of magnetic activity vs. age (see e.g. Žerjal et al 2017;Oláh et al 2016, and references therein)…”

Section: Oláh Et Al (2016) Investigated How Thesupporting

confidence: 93%

Activity cycles in members of young loose stellar associations

Distefano

Lanzafame

Lanza

et al. 2017

A&A

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“…Photospheric component of the flux was eliminated from the active candidates by subtracting the best-matching inactive template spectrum. The activity proxy used is the combined Equivalent Width (EW IRT ) of each calcium line in the spectrum of the star: EW IRT = EW 8498 + EW 8542 + EW 8662 (6) Zerjal et al (2017) found the distribution of EW IRT of inactive stars to be centred around −0.05Å with a σ=0.16Å and hence used 0.16Å as the activity detection limit. Subsequently, out of the 38678 candidate spectra they catalogued, they reported about 13,000 stars with activity level above 2σ and about 22,000 stars with activity above 1σ respectively.…”

Section: Variation Of Host Star Uv Activity With Planet Propertiesmentioning

confidence: 99%

A Statistical Search for Star–Planet Interaction in the Ultraviolet Using GALEX

Viswanath

Narang

Manoj

et al. 2020

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Most (∼82%) of the over 4000 confirmed exoplanets known today orbit very close to their host stars, within 0.5 au. Planets at such small orbital distances can result in significant interactions with their host stars, which can induce increased activity levels in them. In this work, we have searched for statistical evidence for Star-Planet Interactions (SPI) in the ultraviolet (UV) using the largest sample of 1355 GALEX detected host stars with confirmed exoplanets and making use of the improved host star parameters from Gaia DR2. From our analysis, we do not find any significant correlation between the UV activity of the host stars and their planetary properties. We further compared the UV properties of planet host stars to that of chromospherically active stars from the RAVE survey.Our results indicate that the enhancement in chromospheric activity of host stars due to star-planet interactions may not be significant enough to reflect in their near and far UV broad band flux.

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“…UCAC4 544-056450 = TIC 307915958 The position on the color-period diagram is consistent with similar-color members of Group X, implying an age of about 300 Myr. 2MASS J16001203-0230594 = TIC 168457615 The activity and gravity indicators (Bowler et al 2019;Žerjal et al 2017), the lithium non-detection and the position in the CMD close to MS are consistent with an age of few hundreds Myr but we do not have a determination of rotation period to fully confirm and refine it. LSPM J1604+2331 = TIC 445889890 It is a M5 star.…”

Section: Discussionmentioning

confidence: 82%

“…There is no lithium to be seen in the archive FEROS spectrum we analyzed, as also found by Bowler et al (2019), indicating age older than about 100 Myr. High levels of chromospheric and coronal activity have been measured (Bowler et al 2019;Žerjal et al 2017). HD 34652 = TIC 317383399 We measured from TESS photometry a rotation period P= 1.753±0.026 d and a secondary period (of comparable power in both GLS and CLEAN periodograms) P= 1.527 d likely arising from surface differential rotation.…”

Section: Discussionmentioning

confidence: 91%

The GAPS Programme at TNG

Nardiello

Malavolta

Desidera

et al. 2022

A&A

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Context. Great strides have been made in recent years in the understanding of the mechanisms involved in the formation and evolution of planetary systems. Despite this, many observational findings have not yet been corroborated by astrophysical explanations. A fine contribution to the study of planetary formation processes comes from the study of young, low-mass planets, with short orbital periods ( 100 days). In the last three years, the NASA/TESS satellite has identified many planets of this kind and their characterization is clearly necessary in order to understand how they formed and evolved. Aims. Within the framework of the Global Architecture of Planetary System (GAPS) project, we performed a validation and characterization (radius and mass) of the ultra-short period planet TOI-1807 b, which orbits its young host star BD+39 2643 (∼ 300 Myr) in only 13 hours. This is the youngest ultra-short period planet discovered so far. Methods. Thanks to a joint modeling of the stellar activity and planetary signals in the TESS light curve and in new HARPS-N radial-velocity measurements, combined with accurate estimation of stellar parameters, we validated the planetary nature of TOI-1807 b and measured its orbital and physical parameters. Results. By using astrometric, photometric, and spectroscopic observations, we found that BD+39 2643 is a young, active K dwarf star and a member of a 300 ± 80 Myr old moving group. Furthermore, it rotates in P rot = 8.8 ± 0.1 days. This star hosts an ultra-short period planet, exhibiting an orbital period of only P b = 0.54937 ± 0.00001 days. Thanks to the exquisite photometric and spectroscopic series, along with the accurate information on its stellar activity, we measured both the radius and the mass of TOI-1807 b with high precision, obtaining R P,b = 1.37 ± 0.09 R ⊕ and M P,b = 2.57 ± 0.50 M ⊕ . These planet parameters correspond to a rocky planet with an Earth-like density (ρ b = 1.0 ± 0.3 ρ ⊕ ) and no extended H/He envelope. From the analysis of the age-R P distribution for planets with well measured ages, we inferred that TOI-1807 b may have already lost a large part of its atmosphere over the course of its 300 Myr lifetime.

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Chromospherically Active Stars in the Rave Survey. Ii. Young Dwarfs in the Solar Neighborhood

Cited by 25 publications

References 64 publications

Activity cycles in members of young loose stellar associations

Activity cycles in members of young loose stellar associations

A Statistical Search for Star–Planet Interaction in the Ultraviolet Using GALEX

The GAPS Programme at TNG

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