The study of exoplanets and especially their atmospheres can reveal key insights on their evolution by identifying specific atmospheric species. For such atmospheric investigations, high–resolution transmission spectroscopy has shown great success, especially for Jupiter–type planets. Towards the atmospheric characterization of smaller planets, the super–Earth exoplanet 55 Cnc e is one of the most promising terrestrial exoplanets studied to date. Here, we present a high–resolution spectroscopic transit observation of this planet, acquired with the PEPSI instrument at the Large Binocular Telescope. Assuming the presence of Earth–like crust species on the surface of 55 Cnc e, from which a possible silicate–vapor atmosphere could have originated, we search in its transmission spectrum for absorption of various atomic and ionized species such as Fe , Fe ⁺, Ca , Ca ⁺, Mg and K , among others. Not finding absorption for any of the investigated species, we are able to set absorption limits with a median value of 1.9 × R_P. In conclusion, we do not find evidence of a widely extended silicate envelope on this super–Earth reaching several planetary radii.

Read more: Keles et al. 2022, MNRAS, 513, 1544

Hot Jupiters orbiting rapidly rotating stars on inclined orbits undergo tidally induced nodal precession measurable over several years of observations. The Hot Jupiters WASP–33 b and KELT–9 b are particularly interesting targets as they are among the hottest planets found to date, orbiting relatively massive stars. Here, we analyze archival and new data that span 11 and 5 years for WASP–33 b and KELT–9 b, respectively, in order to to model and improve upon their tidal precession parameters. Our work confirms the nodal precession for WASP–33 b and presents the first clear detection of the precession of KELT–9 b. We determine that WASP–33 and KELT–9 have gravitational quadrupole moments. We estimate the planets’ precession periods to be 1460 years and 890 years, respectively, and that they will cease to transit their host stars around the years 2090CE and 2074CE, respectively. Additionally, we investigate both planets’ tidal and orbital evolution, suggesting that a high–eccentricity tidal migration scenario is possible to produce both system architectures and that they will most likely not be engulfed by their hosts before the end of their main sequence lifetimes.

Read more: Stephan et al. 2022, arXiv:2203.02546v1

Hot Jupiters receive intense irradiation from their stellar hosts. The resulting extreme environments in their atmospheres allow us to study the conditions that drive planetary atmospheric dynamics, e.g., global–scale winds. General circulation models predict day–to–nightside winds and equatorial jets with speeds of the order of a few km s^–1. To test these models, we apply high–resolution transmission spectroscopy using the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) spectrograph on the Large Binocular Telescope to study the atmosphere of KELT–9 b, an ultrahot Jupiter and currently the hottest known planet. We measure ~10 km s^–1 day–to–nightside winds traced by Fe II features in the planet’s atmosphere. This is at odds with previous literature (including data taken with PEPSI), which report no significant day–to–nightside winds on KELT–9 b. We identify the cause of this discrepancy as due to an inaccurate ephemeris for KELT–9 b in previous literature.

Read more: Pai Asnodkar et al. 2022, AJ, 163, 155

Transiting hot Jupiters present a unique opportunity to measure absolute planetary masses due to the magnitude of their radial velocity signals and known orbital inclination. Measuring planet mass is critical to understanding atmospheric dynamics and escape under extreme stellar irradiation. Here we present the ultrahot Jupiter system KELT-9 as a double-lined spectroscopic binary. This allows us to directly and empirically constrain the mass of the star and its planetary companion without reference to any theoretical stellar evolutionary models or empirical stellar scaling relations. Using data from the PEPSI, HARPS-N, and TRES spectrographs across multiple epochs, we apply least-squares deconvolution to measure out-of-transit stellar radial velocities. With the PEPSI and HARPS-N data sets, we measure in-transit planet radial velocities using transmission spectroscopy. By fitting the circular orbital solution that captures these Keplerian motions, we recover a planetary dynamical mass of 2.17 ± 0.56 M_J and stellar dynamical mass of 2.11 ± 0.78 M_⊙, both of which agree with the discovery paper. Furthermore, we argue that this system, as well as systems like it, are highly overconstrained, providing multiple independent avenues for empirically cross-validating model-independent solutions to the system parameters. We also discuss the implications of this revised mass for studies of atmospheric escape.

Read more: Pai Asnodkar et al. 2022, AJ, 163, 40P

The O9.7 V star HD 54879 is currently the only massive magnetic star whose magnetic field geometry and rotation period are not constrained. Over the last three years, we gathered additional observations of this star, obtained using various instruments at several astronomical facilities with, the aim to constrain the rotation period and the magnetic field geometry. The new data include the first full Stokes vector observations with the PEPSI spectropolarimeter, installed at the Large Binocular Telescope. The acquired spectropolarimetric observations show a very slow magnetic field variability related to the extremely slow rotation of HD 54879, which is also indicated in a dynamical spectrum, displaying variability of the Hα line.

Generally, magnetic massive O- and B-type stars exhibit a smooth, single-wave variation of the longitudinal magnetic field during the stellar rotation cycle. The approximately sinusoidal variation of ⟨Bz⟩ and the ratio of the values of the ⟨Bz⟩ extrema in previously studied stars suggest that there is an important component of the field that is dipolar. Assuming that the magnetic field of HD 54879 has a pure dipolar configuration and that the negative field extremum is indeed around −570 G and not at a lower value, we fitted a cosine curve to the observed distribution of data points obtained from the high-resolution spectropolarimetric observations and determined a stellar rotation period of 7.2 yr. Certainly, further monitoring of the magnetic field variability is needed to determine the rotation period with more confidence. We note, that magnetic studies of several O-type stars indicate that only one magnetic pole is well visible while the star rotates, implying that the magnetic field structure over the fraction of their invisible surface remains unconstrained.

Read more: Järvinen et al. 2022, MNRAS, 501, 4405. arXiv

We present the first short time scale observations of the roAp star γ Equ in linear polarized light obtained with the PEPSI polarimeter installed at the LBT. These observations are used to search for pulsation variability in Stokes Q and U line profiles belonging to different elements. The atmospheres of roAp stars are significantly stratified with spectral lines of different elements probing different atmospheric depths. roAp stars with strong magnetic fields, such as γ Equ with a magnetic field modulus of 4 kG and a pulsation period of 12.21 min, are of special interest because the effect of the magnetic field on the structure of their atmospheres can be studied with greatest detail and accuracy. Our results show that we may detect changes in the transversal field component in Fe I and rare-earth lines possessing large second-order Landé factors. Such variability can be due to the impact of pulsation on the transverse magnetic field, causing changes in the obliquity angles of the magnetic force lines. Further studies of roAp stars in linear polarized light and subsequent detailed modelling are necessary to improve our understanding of the involved physics.

Read more: Hubrig et al. 2021, MNRAS 508 L17. arXiv:2108.11272

By measuring the elemental abundances of a star, we can gain insight into the composition of its initial gas cloud — the formation site of the star and its planets. Planet formation requires metals, the availability of which is determined by the elemental abundance. In the case where metals are extremely deficient, planet formation can be stifled. To investigate such a scenario requires a large sample of metal-poor stars and a search for planets therein. This paper focuses on the selection and validation of a halo star sample. We select ~17,000 metal-poor halo stars based on their Galactic kinematics, and confirm their low metallicities ([Fe/H] < -0.5), using spectroscopy from the literature. Furthermore, we perform high-resolution spectroscopic observations using LBT/PEPSI and conduct detailed metallicity ([Fe/H]) analyses on a sample of 13 previously known halo stars that also have hot kinematics. We can use the halo star sample presented here to measure the frequency of planets and to test planet formation in extremely metal-poor environments.

Read more: Kolecki et al. 2021, AJ, 162, 125. arXiv:2106.13251

While steady empirical progress has been made in understanding the structure and composition of hot planet atmospheres, direct measurements of velocity signatures, including winds, rotation, and jets, have lagged behind. Quantifying atmospheric dynamics of hot planets is critical to a complete understanding of their atmospheres and such measurements may even illuminate other planetary properties, such as magnetic field strengths. In this manuscript, we present the first detection of the Balmer lines H-alpha and H-beta in the atmosphere of the ultra-hot Jupiter WASP-33b. Using atmospheric models which include the effects of atmospheric dynamics, we show that the shape of the average Balmer line transmission spectrum is consistent with rotational velocities in the planet’s thermosphere of vrot = 10.1 (+0.8 -1.0) km/s. We also measure a low-significance day-to-night side velocity shift of -4.6 +/-3.4 km/s in the transmission spectrum which is naturally explained by a global wind across the planet’s terminator. In a separate analysis the time-resolved velocity centroids of individual transmission spectra show unambiguous evidence of rotation, with a best-fit velocity of 10.0 (+2.4 -2.0) km/s, consistent with the value of vrot derived from the shape of the average Balmer line transmission spectrum. Our observations and analysis confirm the power of high signal-to-noise, time resolved transmission spectra to measure the velocity structures in exoplanet atmospheres. The large rotational and wind velocities we measure highlight the need for more detailed 3D global climate simulations of the rareed upper-atmospheres of ultra-hot gas giants.

Read more: Cauley et al. 2021, AJ, 161, 152

We report the discovery of the closest known black hole candidate as a binary companion to V723 Mon. V723 Mon is a nearby (d=460 pc), bright evolved red giant in a high mass function nearly circular binary (𝑃 = 59•.9 d, e approx. 0). Analyses of the stellar spectra and spectral energy distribution (SED) give 𝑇_eff =– 4440 K, 𝐿 = 173 𝐿s_⊙ and 𝑅 = 22 𝑅_⊙. Matching these parameters to MIST evolutionary models indicates a mass of the visible giant of 𝑀_giant = 1.•07 +/- 0.•24 𝑀_⊙. V723 Mon is a known variable star, previously classified as an eclipsing binary, but its All-Sky Automated Survey (ASAS), Kilodegree Extremely Little Telescope (KELT), and Transiting Exoplanet Survey Satellite (TESS) light curves are those of a nearly edge-on ellipsoidal variable. Detailed models of the light curves constrained by the period, radial velocities and stellar temperature give an inclination of 𝑖 = 87• deg, a mass ratio of 0•.30 +/- 0•.02, and a  companion mass of 𝑀_comp = 2.•91 +/- 0•.08 𝑀_⊙, a stellar radius of the giant of 𝑅_giant = 23.•6 +/-1.•0 𝑅_⊙, and a giant mass of 𝑀_giant = 0.•87 +/-0.•08 𝑀_⊙ , consistent with our other estimates. We identify a likely non-stellar, diffuse veiling component with contributions in the 𝐵 and 𝑉-band of ~64% and ~23%, respectively, and a luminosity of ~20 𝐿_⊙. The SED and the absence of continuum eclipses imply that the companion mass must be dominated by a compact object even if the companion is a binary. We do observe eclipses of the Balmer lines when the dark companion passes behind the giant, but their velocity spreads are low compared to observed accretion disks. The X-ray luminosity of the system is 𝐿_X = 1• x 10^30 erg/s, corresponding to 𝐿/𝐿_edd ~10^-9. The simplest explanation for the massive companion is a single compact object, most likely a black hole in the “mass gap”, although a double neutron star binary is possible.

Read more: Jayasinghe et al. 2021, MNRAS, 504, 2577

NGC 1624-2 is an O7f?p star with a reported probable polar magnetic field strength ≥20 kG, which is the strongest magnetic field ever measured in an O-type star. We study the variability of the mean longitudinal magnetic field <B_z> and the mean field modulus to obtain constraints on its field geometry. Only one magnetic pole is observable over the rotation cycle. The approximately sinusoidal variation of <B_z> and the ratio of the values of the extrema of indicate that there is an important component of the field that is dipolar. The <B_z> values measured over the rotation cycle are in the range from -0.2 to 4.5 kG, whereas the values for vary between 9 and 12 kG. The <B_z> values obtained using the O III λ7455 emission line are in the range from 0.4 to 2.3 kG and show a variability pattern similar to that detected for the absorption lines. The fact that the phase of the <B_z> minimum coincides with the phase of the maximum, indicates that the field structure must significantly depart from a centred dipole. Further, we discuss the nature of the observed variable Stokes V profiles corresponding to a longitudinal field of negative polarity detected in the emission He I lines and present the first magnetohydrodynamical numerical simulations of the gas flow in the magnetosphere of this star.

Read more: Järvinen et al., 2021, MNRAS, 501, 4534, in arXiv