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1. Rotation Periods of TESS Objects of Interest from the Magellan-TESS Survey with Multiband Photometry from Evryscope and TESS

   https://doi.org/10.3847/1538-3881/ac0fe3  

   Howard, Ward S; Teske, Johanna; Corbett, Hank; Law, Nicholas M; Wang, Sharon Xuesong; Ratzloff, Jeffrey K; Galliher, Nathan W; Gonzalez, Ramses; Soto, Alan Vasquez; Glazier, Amy L; et al (September 2021, The Astronomical Journal)

   Abstract Stellar radial-velocity (RV) jitter due to surface activity may bias the RV semiamplitude and mass of rocky planets. The amplitude of the jitter may be estimated from the uncertainty in the rotation period, allowing the mass to be more accurately obtained. We find candidate rotation periods for 17 out of 35 TESS Objects of Interest (TOI) hosting <3R_⊕planets as part of the Magellan-TESS survey, which is the first-ever statistically robust study of exoplanet masses and radii across the photoevaporation gap. Seven periods are ≥3σdetections, two are ≥1.5σ, and eight show plausible variability, but the periods remain unconfirmed. The other 18 TOIs are nondetections. Candidate rotators include the host stars of the confirmed planets L 168-9 b, the HD 21749 system, LTT 1445 A b, TOI 1062 b, and the L 98-59 system. Thirteen candidates have no counterpart in the 1000 TOI rotation catalog of Canto Martins et al. We find periods for G3–M3 dwarfs using combined light curves from TESS and the Evryscope all-sky array of small telescopes, sometimes with longer periods than would be possible with TESS alone. Secure periods range from 1.4 to 26 days with Evryscope-measured photometric amplitudes as small as 2.1 mmag in $g\prime$. We also apply Monte Carlo sampling and a Gaussian process stellar activity model fromexoplanetto the TESS light curves of six TOIs to confirm the Evryscope periods. 

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2. Planet Hunters TESS II: Findings from the first two years of TESS

   https://doi.org/10.1093/mnras/staa3739  

   Eisner, N L; Barragán, O; Lintott, C; Aigrain, S; Nicholson, B; Boyajian, T S; Howell, S; Johnston, C; Lakeland, B; Miller, G; et al (December 2020, Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   Abstract We present the results from the first two years of the Planet Hunters TESS citizen science project, which identifies planet candidates in the TESS data by engaging members of the general public. Over 22,000 citizen scientists from around the world visually inspected the first 26 Sectors of TESS data in order to help identify transit-like signals. We use a clustering algorithm to combine these classifications into a ranked list of events for each sector, the top 500 of which are then visually vetted by the science team. We assess the detection efficiency of this methodology by comparing our results to the list of TESS Objects of Interest (TOIs) and show that we recover 85 % of the TOIs with radii greater than 4 ⊕ and 51 % of those with radii between 3 and 4 R⊕. Additionally, we present our 90 most promising planet candidates that had not previously been identified by other teams, 73 of which exhibit only a single transit event in the TESS light curve, and outline our efforts to follow these candidates up using ground-based observatories. Finally, we present noteworthy stellar systems that were identified through the Planet Hunters TESS project. 

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3. TESS first look at evolved compact pulsators: Known ZZ Ceti stars of the southern ecliptic hemisphere as seen by TESS

   https://doi.org/10.1051/0004-6361/202037470  

   Bognár, Zs.; Kawaler, S. D.; Bell, K. J.; Schrandt, C.; Baran, A. S.; Bradley, P. A.; Hermes, J. J.; Charpinet, S.; Handler, G.; Mullally, S. E.; et al (June 2020, Astronomy & Astrophysics)

   null (Ed.)

   Context. We present our findings on 18 previously known ZZ Ceti stars observed by the TESS space telescope in 120 s cadence mode during the survey observation of the southern ecliptic hemisphere. Aims. We focus on the frequency analysis of the space-based observations, comparing the results with findings of previous ground-based measurements. The frequencies detected by the TESS observations can serve as inputs for future asteroseismic analyses. Methods. We performed standard pre-whitening of the data sets to derive the possible pulsation frequencies of the different targets. In some cases, we fit Lorentzians to the frequency groups that emerged as the result of short-term amplitude or phase variations that occurred during the TESS observations. Results. We detected more than 40 pulsation frequencies in seven ZZ Ceti stars observed in the 120 s cadence by TESS, with precision better than 0.1  μ Hz. We found that HE 0532−5605 may be a new outbursting ZZ Ceti. Ten targets do not show any significant pulsation frequencies in their Fourier transforms, due to a combination of their intrinsic faintness and/or crowding on the large TESS pixels. We also detected possible amplitude or phase variations during the TESS observations in some cases. Such behaviour in these targets was not previously identified from ground-based observations. 

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4. Searching the SN 1987A SETI Ellipsoid with TESS

   https://doi.org/10.3847/1538-3881/ad2064  

   Cabrales, Bárbara; Davenport, James R. A.; Sheikh, Sofia; Croft, Steve; Siemion, Andrew P. V.; Giles, Daniel; Cody, Ann Marie (February 2024, The Astronomical Journal)

   Abstract The SETI Ellipsoid is a strategy for technosignature candidate selection that assumes that extraterrestrial civilizations who have observed a galactic-scale event—such as supernova 1987A—may use it as a Schelling point to broadcast synchronized signals indicating their presence. Continuous wide-field surveys of the sky offer a powerful new opportunity to look for these signals, compensating for the uncertainty in their estimated time of arrival. We explore sources in the TESS continuous viewing zone, which corresponds to 5% of all TESS data, observed during the first 3 yr of the mission. Using improved 3D locations for stars from Gaia Early Data Release 3, we identified 32 SN 1987A SETI Ellipsoid targets in the TESS continuous viewing zone with uncertainties better than 0.5 lt-yr. We examined the TESS light curves of these stars during the Ellipsoid crossing event and found no anomalous signatures. We discuss ways to expand this methodology to other surveys, more targets, and different potential signal types. 

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5. Revealing AGNs through TESS variability

   https://doi.org/10.1093/mnras/stad2530  

   Treiber, Helena_P; Hinkle, Jason_T; Fausnaugh, Michael_M; Shappee, Benjamin_J; Kochanek, Christopher_S; Vallely, Patrick_J; Auchettl, Katie; Holoien, Thomas_W-S; Payne, Anna_V; Dai, Xinyu (September 2023, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We used Transiting Exoplanet Survey Satellite (TESS) data to identify 29 candidate active galactic nuclei (AGNs) through their optical variability. The high-cadence, high-precision TESS light curves present an opportunity for the identification of AGNs, including those not selected through other methods. Of the candidates, we found that 18 have either previously been identified as AGNs in the literature or could have been selected based on emission-line diagnostics, mid-IR colours, or X-ray luminosity. AGNs in low-mass galaxies offer a unique window into supermassive black hole and galaxy co-evolution and 8 of the 29 candidates have estimated black hole masses ≲ 106 M⊙. The low-mass galaxies NGC 4395 and NGC 4449 are two of our five ‘high-confidence’ candidates. Since our initial sample largely draws from just nine TESS sectors, we expect to identify at least ∼45 more candidates in the TESS primary and extended mission data sets, of which ∼60 per cent will be new AGNs and ∼20 per cent will be in low-mass galaxies. 

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