TESS Hunt for Young and Maturing Exoplanets (THYME). VII. Membership, Rotation, and Lithium in the Young Cluster Group-X and a New Young Exoplanet

Newton, Elisabeth R.; Rampalli, Rayna; Kraus, Adam L.; Mann, Andrew W.; Curtis, Jason L.; Vanderburg, Andrew; Krolikowski, Daniel M.; Huber, Daniel; Petter, Grayson C.; Bieryla, Allyson; Tofflemire, Benjamin M.; Thao, Pa Chia; Wood, Mackenna L.; Kerr, Ronan; Safonov, Boris; Strakhov, Ivan A.; Ciardi, David R.; Giacalone, Steven; Dressing, Courtney D.; Gill, Holden; Savel, Arjun B.; Collins, Karen A.; Stassun, Keivan G.; Murgas, F.; Isogai, Keisuke; Narita, Norio; Πάλλη, Ε.; Quinn, Samuel N.; Eastman, Jason D.; Fürész, Gábor; Shiao, Bernie; Daylan, Tansu; Caldwell, Douglas A.; Ricker, G.; Vanderspek, R.; Winn, Joshua N.; Winn, Joshua N.; Jenkins, Jon M.; Latham, David W.

doi:10.3847/1538-3881/ac8154

“…The top plot of Figure 6 shows the rotation period of TOI-4562 compared with stars of known nearby clusters and associations. TOI-4562's P å is consistent with that of stars belonging to Group X (Messina et al 2022;Newton et al 2022), with an estimated age of 300 Myr.…”

Section: Stellar Rotation and Gyrochronologysupporting

confidence: 55%

TOI-4562b: A Highly Eccentric Temperate Jupiter Analog Orbiting a Young Field Star

Heitzmann

¹

,

Zhou

²

,

Quinn

³

et al. 2023

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We report the discovery of TOI-4562b (TIC-349576261), a Jovian planet orbiting a young F7V-type star, younger than the Praesepe/Hyades clusters (<700 Myr). This planet stands out because of its unusually long orbital period for transiting planets with known masses (P orb = 225.11781 − 0.00022 + 0.00025 days) and because it has a substantial eccentricity (e = 0.76 − 0.02 + 0.02 ). The location of TOI-4562 near the southern continuous viewing zone of TESS allowed observations throughout 25 sectors, enabling an unambiguous period measurement from TESS alone. Alongside the four available TESS transits, we performed follow-up photometry using the South African Astronomical Observatory node of the Las Cumbres Observatory and spectroscopy with the CHIRON spectrograph on the 1.5 m SMARTS telescope. We measure a radius of 1.118 + 0.013 − 0.014 R J and a mass of 2.30 − 0.47 + 0.48 M J for TOI-4562b. The radius of the planet is consistent with contraction models describing the early evolution of the size of giant planets. We detect tentative transit timing variations at the ∼20 minutes level from five transit events, favoring the presence of a companion that could explain the dynamical history of this system if confirmed by future follow-up observations. With its current orbital configuration, tidal timescales are too long for TOI-4562b to become a hot Jupiter via high-eccentricity migration though it is not excluded that interactions with the possible companion could modify TOI-4562b’s eccentricity and trigger circularization. The characterization of more such young systems is essential to set constraints on models describing giant-planet evolution.

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“…PDCSAP flux is effective at removing long-term trends. Newton et al (2022) find that PDCSAP could also effect the observed rotation signature in some sectors; comparison of the SAP and PDCSAP light curves for stars in our sample indicates this is not a concern for us. Thus, for this paper we use the PDCSAP flux.…”

Section: Optical Photometric Datamentioning

confidence: 55%

Contemporaneous Observations of Hα Luminosities and Photometric Amplitudes for M Dwarfs

Soto

¹

,

Newton

²

,

Douglas

³

et al. 2023

AJ

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While many M dwarfs are known to have strong magnetic fields and high levels of magnetic activity, we are still unsure about the properties of their starspots and the origin of their magnetic dynamos. Both starspots and chromospheric heating are generated by the surface magnetic field; they produce photometric variability and Hα emission, respectively. Connecting brightness variations to magnetic activity therefore provides a means to examine M-dwarf magnetism. We survey 30 M dwarfs previously identified as fast rotating stars (P rot < 10 days). We present time-series optical photometry from the Transiting Exoplanet Survey Satellite (TESS) and contemporaneous optical spectra obtained using the Ohio State Multi-Object Spectrograph (OSMOS) on the 2.4 m Hiltner telescope at MDM Observatory in Arizona. We measure rotation periods and photometric amplitudes from TESS light curves using Gaussian Processes. From the OSMOS spectra, we calculate the equivalent width of Hα, and L Hα /L bol. We find a weak positive correlation between Hα luminosity and the semiamplitude, R var ( p = 0.005 − 0.005 + 0.075 ). We also observe short-term variability (between 20 and 45 minutes) in Hα equivalent widths and possible enhancement from flares consistent to recent literature.

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“…The closest case is MELANGE-1, which is closer in age (∼250 Myr; Tofflemire et al 2021) and hence has similar large V off scatters. Most of the stars in MELANGE-2 (Newton et al 2022) and MELANGE-3 (Barber et al 2022) that agree in RV space are within 1-2 km s −1 in V off .…”

Section: A Potential ∼200 Myr Young Association Candidate In the Phoe...mentioning

confidence: 80%

“…Similarly, the Pleiades, Hyades, and Praesepe clusters are shown for comparison. We add the P ROT distribution of Group X members (∼300 Myr, Newton et al 2022). The left panel shows all RV comoving candidates where P ROT are derived.…”

Section: Stellar Rotational Periodmentioning

confidence: 99%

“…In this work, we present a different approach to identifying stellar siblings and young association candidates where a planet resides, which, in turn, helps to constrain its age. This method has successfully identified the 250 Myr MELANGE-1 (Tofflemire et al 2021), the MELANGE-2 (Newton et al 2022), and the Pleiades-aged MELANGE-3 (Barber et al 2022) association (candidate). The increasing number of planets found in stellar associations would help to answer whether the planet occurrence rate in stellar associations shows any difference from that in the field stars, which is essential for understanding the early planet formation and evolution conditions (Dai et al 2021).…”

Section: Introductionmentioning

confidence: 99%

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A Search for Stellar Siblings of the ∼200 Myr TOI-251 b Planetary System

Sun

¹

,

Wang

²

,

Mann

³

et al. 2023

ApJ

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Young planets (<1 Gyr) are helpful for studying the physical processes occurring at the early stage of planet evolution. TOI-251 b is a recently discovered sub-Neptune orbiting a young G dwarf, which has an imprecise age estimation of 40–320 Myr. We select TOI-251 sibling candidates based on kinematics and spatial proximity to TOI-251 and further use the color–magnitude diagram to refine the list and to compare to multiple open clusters. We report the stellar rotational period for 321 sibling candidates in a 50 pc radius around TOI-251 by analyzing their stellar light curves and find a color–rotational period sequence that lies in between the Group X (300 Myr) and Pleiades (120 Myr) members, suggesting an age ∼ 200 Myr. A quantitative age analysis using gyrochronology relations gives 204 ± 45 Myr, consistent with the average Li age of selected siblings (238 ± 38 Myr) and the Gaia variability age (193 − 54 102 Myr). The detection fraction of comoving candidates that have a short rotational period is 68.1%, much higher than the typical value in the field (14%–16% from Kepler). The overdensity of young stars and consistency in age of stellar siblings suggest a potential young association candidate in the Phoenix–Grus constellation. Though TOI-251 b has a radius larger than most of its field-age counterparts, we are uncertain whether TOI-251 is inflated, due to a lack of knowledge on the planet’s mass.

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TESS Hunt for Young and Maturing Exoplanets (THYME). VII. Membership, Rotation, and Lithium in the Young Cluster Group-X and a New Young Exoplanet

Cited by 22 publications

References 154 publications

TOI-4562b: A Highly Eccentric Temperate Jupiter Analog Orbiting a Young Field Star

TOI-4562b: A Highly Eccentric Temperate Jupiter Analog Orbiting a Young Field Star

Contemporaneous Observations of Hα Luminosities and Photometric Amplitudes for M Dwarfs

A Search for Stellar Siblings of the ∼200 Myr TOI-251 b Planetary System

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