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1. The Directly Imaged Exoplanet Host Star 51 Eridani is a Gamma Doradus Pulsator

   https://doi.org/10.3847/1538-4357/ac9229  

   Sepulveda, Aldo G. ; Huber, Daniel ; Zhang, Zhoujian ; Li, Gang ; Liu, Michael C. ; Bedding, Timothy R. ( October 2022 , The Astrophysical Journal)

   51 Eri is well known for hosting a directly imaged giant planet and for its membership to theβPictoris moving group. Using 2 minute cadence photometry from the Transiting Exoplanet Survey Satellite (TESS), we detect multiperiodic variability in 51 Eri that is consistent with pulsations of Gamma Doradus (γDor) stars. We identify the most significant pulsation modes (with frequencies between ∼0.5 and 3.9 cycles day⁻¹and amplitudes ranging between ∼1 and 2 mmag) as dipole and quadrupole gravity modes, as well as Rossby modes, as previously observed in KeplerγDor stars. Our results demonstrate that previously reported variability attributed to stellar rotation is instead likely due toγDor pulsations. Using the mean frequency of theℓ= 1 gravity modes, together with empirical trends of the KeplerγDor population, we estimate a plausible stellar core rotation period of${0.9}_{-0.1}^{+0.3}$days for 51 Eri. We find no significant evidence for transiting companions around 51 Eri in the residual light curve. The detection ofγDor pulsations presented here, together with follow-up observations and modeling, may enable the determination of an asteroseismic age for this benchmark system. Future TESS observations would allow a constraint on the stellar core rotation rate, which in turn traces the surface rotation rate, and thus would help clarify whether or not the stellar equatorial plane and orbit of 51 Eri b are coplanar.

    

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2. TESS Asteroseismic Analysis of HD 76920: The Giant Star Hosting an Extremely Eccentric Exoplanet

   https://doi.org/10.3847/1538-4357/acb8ac  

   Jiang 姜, Chen 晨. ; Wu 吴涛, Tao ; Feinstein, Adina D. ; Stassun, Keivan G. ; Bedding, Timothy R. ; Veras, Dimitri ; Corsaro, Enrico ; Buzasi, Derek L. ; Stello, Dennis ; Li 李亚光, Yaguang ; et al ( March 2023 , The Astrophysical Journal)

   The Transiting Exoplanet Survey Satellite (TESS) mission searches for new exoplanets. The observing strategy of TESS results in high-precision photometry of millions of stars across the sky, allowing for detailed asteroseismic studies of individual systems. In this work, we present a detailed asteroseismic analysis of the giant star HD 76920 hosting a highly eccentric giant planet (e= 0.878) with an orbital period of 415 days, using five sectors of TESS light curve that cover around 140 days of data. Solar-like oscillations in HD 76920 are detected around 52μHz by TESS for the first time. By utilizing asteroseismic modeling that takes classical observational parameters and stellar oscillation frequencies as constraints, we determine improved measurements of the stellar mass (1.22 ± 0.11M_⊙), radius (8.68 ± 0.34R_☉), and age (5.2 ± 1.4 Gyr). With the updated parameters of the host star, we update the semimajor axis and mass of the planet asa= 1.165 ± 0.035 au and$M_{\mathrm{p}}\sin i=3.57\pm 0.22M_{\mathrm{Jup}}$. With an orbital pericenter of 0.142 ± 0.005 au, we confirm that the planet is currently far away enough from the star to experience negligible tidal decay until being engulfed in the stellar envelope. We also confirm that this event will occur within about 100 Myr, depending on the stellar model used.

    

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3. CLASS Angular Power Spectra and Map-component Analysis for 40 GHz Observations through 2022

   https://doi.org/10.3847/1538-4357/ad1abf  

   Eimer, Joseph R. ; Li 李, Yunyang 云炀 ; Brewer, Michael K. ; Shi 时, Rui 瑞. ; Ali, Aamir ; Appel, John W. ; Bennett, Charles L. ; Bruno, Sarah Marie ; Bustos, Ricardo ; Chuss, David T. ; et al ( March 2024 , The Astrophysical Journal)

   Measurement of the largest angular scale (ℓ< 30) features of the cosmic microwave background (CMB) polarization is a powerful way to constrain the optical depth to reionization and search for the signature of inflation through the detection of primordialB-modes. We present an analysis of maps covering 73.6% of the sky made from the 40 GHz channel of the Cosmology Large Angular Scale Surveyor (CLASS) from 2016 August to 2022 May. Taking advantage of the measurement stability enabled by front-end polarization modulation and excellent conditions from the Atacama Desert, we show this channel achieves higher sensitivity than the analogous frequencies from satellite measurements in the range 10 <ℓ< 100. Simulations show the CLASS linear (circular) polarization maps have a white noise level of$125(130)\mu \mathrm{K}\mathrm{arcmin}$. We measure the Galaxy-maskedEEandBBspectra of diffuse synchrotron radiation and compare to space-based measurements at similar frequencies. In combination with external data, we expand measurements of the spatial variations of the synchrotron spectral energy density (SED) to include new sky regions and measure the diffuse SED in the harmonic domain. We place a new upper limit on a background of circular polarization in the range 5 <ℓ< 125 with the first bin showingD_ℓ< 0.023$\mu {\mathrm{K}}_{\mathrm{CMB}}^2$at 95% confidence. These results establish a new standard for recovery of the largest-scale CMB polarization from the ground and signal exciting possibilities when the higher sensitivity and higher-frequency CLASS channels are included in the analysis.

    

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4. TESS first look at evolved compact pulsators: Asteroseismology of the pulsating helium-atmosphere white dwarf TIC 257459955

   https://doi.org/10.1051/0004-6361/201936340  

   Bell, Keaton J. ; Córsico, Alejandro H. ; Bischoff-Kim, Agnès ; Althaus, Leandro G. ; Bradley, Paul A. ; Calcaferro, Leila M. ; Montgomery, Michael H. ; Uzundag, Murat ; Baran, Andrzej S. ; Bognár, Zsófia ; et al ( December 2019 , Astronomy & Astrophysics)

   Context. Pulsation frequencies reveal the interior structures of white dwarf stars, shedding light on the properties of these compact objects that represent the final evolutionary stage of most stars. Two-minute cadence photometry from the Transiting Exoplanet Survey Satellite (TESS) records pulsation signatures from bright white dwarfs over the entire sky. Aims. As part of a series of first-light papers from TESS Asteroseismic Science Consortium Working Group 8, we aim to demonstrate the sensitivity of TESS data, by measuring pulsations of helium-atmosphere white dwarfs in the DBV instability strip, and what asteroseismic analysis of these measurements can reveal about their stellar structures. We present a case study of the pulsating DBV WD 0158−160 that was observed as TIC 257459955 with the two-minute cadence for 20.3 days in TESS Sector 3. Methods. We measured the frequencies of variability of TIC 257459955 with an iterative periodogram and prewhitening procedure. The measured frequencies were compared to calculations from two sets of white dwarf models to constrain the stellar parameters: the fully evolutionary models from LPCODE and the structural models from WDEC . Results. We detected and measured the frequencies of nine pulsation modes and eleven combination frequencies of WD 0158−160 to ∼0.01  μ Hz precision. Most, if not all, of the observed pulsations belong to an incomplete sequence of dipole (ℓ = 1) modes with a mean period spacing of 38.1 ± 1.0 s. The global best-fit seismic models from both LPCODE and WDEC have effective temperatures that are ≳3000 K hotter than archival spectroscopic values of 24 100–25 500 K; however, cooler secondary solutions are found that are consistent with both the spectroscopic effective temperature and distance constraints from Gaia astrometry. Conclusions. Our results demonstrate the value of the TESS data for DBV white dwarf asteroseismology. The extent of the short-cadence photometry enables reliably accurate and extremely precise pulsation frequency measurements. Similar subsets of both the LPCODE and WDEC models show good agreement with these measurements, supporting that the asteroseismic interpretation of DBV observations from TESS is not dominated by the set of models used. However, given the sensitivity of the observed set of pulsation modes to the stellar structure, external constraints from spectroscopy and/or astrometry are needed to identify the best seismic solutions. 

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5. Search for Higgs boson decays to a Z boson and a photon in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP05(2023)233  

   Tumasyan, A. ; Adam, W. ; Andrejkovic, J. W. ; Bergauer, T. ; Chatterjee, S. ; Damanakis, K. ; Dragicevic, M. ; Escalante Del Valle, A. ; Frühwirth, R. ; Jeitler, M. ; et al ( May 2023 , Journal of High Energy Physics)

   Results are presented from a search for the Higgs boson decay H→Zγ, where Z→ ℓ⁺ℓ⁻withℓ= e or μ. The search is performed using a sample of proton-proton (pp) collision data at a center-of-mass energy of 13 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb⁻¹. Events are assigned to mutually exclusive categories, which exploit differences in both event topology and kinematics of distinct Higgs production mechanisms to enhance signal sensitivity. The signal strengthμ, defined as the product of the cross section and the branching fraction$$ \left[\sigma \left(\textrm{pp}\to \textrm{H}\right)\mathcal{B}\left(\textrm{H}\to \textrm{Z}\upgamma \right)\right] $$$\left(\sigma \left(\mathrm{pp}\to H\right)B\left(H\to \mathrm{Z\gamma }\right)\right)$relative to the standard model prediction, is extracted from a simultaneous fit to theℓ⁺ℓ⁻γ invariant mass distributions in all categories and is measured to beμ= 2.4 ± 0.9 for a Higgs boson mass of 125.38 GeV. The statistical significance of the observed excess of events is 2.7 standard deviations. This measurement corresponds to$$ \left[\sigma \left(\textrm{pp}\to \textrm{H}\right)\mathcal{B}\left(\textrm{H}\to \textrm{Z}\upgamma \right)\right]=0.21\pm 0.08 $$$\left(\sigma \left(\mathrm{pp}\to H\right)B\left(H\to \mathrm{Z\gamma }\right)\right)=0.21\pm 0.08$pb. The observed (expected) upper limit at 95% confidence level onμis 4.1 (1.8), where the expected limit is calculated under the background-only hypothesis. The ratio of branching fractions$$ \mathcal{B}\left(\textrm{H}\to \textrm{Z}\upgamma \right)/\mathcal{B}\left(\textrm{H}\to \upgamma \upgamma \right) $$$B\left(H\to \mathrm{Z\gamma }\right)/B\left(H\to \mathrm{\gamma \gamma }\right)$is measured to be$$ {1.5}_{-0.6}^{+0.7} $$${1.5}_{-0.6}^{+0.7}$, which agrees with the standard model prediction of 0.69 ± 0.04 at the 1.5 standard deviation level.

    

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