Hamburg Observatory

Luminous quasars at the redshift frontier z > 7 serve as stringent probes of super-massive black hole (SMBH) formation and they are thought to undergo much of their growth obscured by dense gas and dust in their host galaxies. Fully characterizing the symbiotic evolution of SMBHs and hosts requires rest-frame optical observations that span spatial scales from the broad-line region (BLR) to the interstellar and circumgalactic medium (ISM and CGM). The James Webb Space Telescope (JWST) now provides the necessary spatially resolved spectroscopy to do so. However, the physical conditions that regulate the interplay between SMBHs and their hosts at the highest redshifts, especially the nature of early feedback phases, remain unclear. We present JWST/NIRSpec integral field unit (IFU) observations of J0313-1806 at z = 7.64, the most distant luminous quasar known. From the rest-frame optical spectrum of the unresolved quasar, we derived a black hole mass of M-BH = (1.63 +/- 0.10)& times;10(9) M-circle dot based on H beta lambda 4861 (H beta) and an Eddington rate of lambda = L/L-Edd = 0.80 +/- 0.05, consistent with previous Mg II lambda 2800-based estimates. J0313-1806 exhibits no detectable [O III] lambda lambda 4959, 5007 emission on nuclear scales (3 sigma upper limit equivalent width of [O III] lambda 5007 < 1.42 & Aring;). Most remarkably, we did detect an ionized gas shell extending out to similar to 1.8 kpc traced by H beta emission that also lacks any significant [O III] lambda lambda 4959, 5007, with a 3 sigma upper limit on the [O III] lambda 5007 to H beta flux ratio of log(10)(F([O III])/F(H beta)) = -1.15. Through photoionization modeling, we demonstrate that the extended emission is consistent with a thin, clumpy outflowing shell where [O III] is collisionally de-excited by dense gas. We interpret this structure as a fossil remnant of a recent blowout phase, providing evidence for episodic feedback cycles in one of the earliest quasars. These findings suggest that dense ISM phases may play a crucial role in shaping the spectral properties of quasars across cosmic time.

Owing to hot and inflated envelopes that facilitate atmospheric studies, ultrahot Jupiters (UHJs) have attracted much attention. Significant progress has been achieved, from enlarging the sample size to broadening the studies to encompass diverse stellar types and ages. Here, we present a transmission spectroscopy study of HAT-P-70b, a UHJ orbiting a young A-type star, through high-resolution observations with CARMENES at the 3.5 m Calar Alto telescope. By using the line-by-line technique, we confirm the previous detections of H α , Na i , and Ca ii , report a new tentative detection of K i , and impose an upper limit on the He triplet absorption. Through cross-correlation analysis, we identify the Ca ii and Fe i absorptions, both blueshifted by approximately 5 km s ^−1 , indicating a day-to-night side atmospheric wind. Additionally, we find a new tentative detection of K i . We do not see any significant atmospheric molecular signal in the near-infrared data. Putting HAT-P-70b in the context of UHJs from the literature, it turns out that (1) H α absorption is more common on gas giants orbiting stars younger than 1 Gyr, with a relative detection probability of P _Age<1 Gyr (H α )/ P _Age≥1 Gyr (H α ) ∼ 3; (2) any UHJ is likely to exhibit Fe i absorption if it has Ca ii .

Correctly interpreting JWST spectra of close-in exoplanets requires a measurement of the X-ray and ultraviolet light that the planets receive from their host stars. Here, we provide spectral energy distributions (SEDs) covering the range ≈5–1 × 10 ^7 Å for 20 transiting exoplanet host stars observed in JWST Cycle 1. The SEDs are constructed out of new and archival Hubble Space Telescope, Chandra X-ray Observatory, and/or XMM-Newton data combined with spectra from models or stars with similar properties (proxies) filling in unobserved gaps. We have also constructed SEDs of likely Habitable Worlds Observatory targets κ ^1 Ceti, τ Ceti, ϵ Indi, and 70 Oph B for use as proxies. We find that the JWST target planets almost all experience much stronger ultraviolet fluxes than the Earth, especially in the extreme ultraviolet, even for planets with similar overall instellation. Strong ongoing or past atmospheric escape is possible for a majority of these planets. We also assess the now considerable sample of panchromatic stellar SEDs and its applicability for current JWST observations and beyond.

Context. The F-, G-, K-, and M-type stars are the most abundant stellar population in the Milky Way and are expected to contribute to its diffuse X-ray emission. Yet their intrinsic average X-ray spectrum remains poorly constrained due to their faint X-ray luminosities, leaving their collective role in the X-ray background of the Milky Way uncertain. Aims. We aim to derive a distance-normalised average X-ray spectrum for nearby M dwarfs and F, G, and K stars and to characterise their ensemble spectral properties. Methods. We analysed the volume-complete sample of M dwarfs (M0-M6) and F, G, and K stars within 10 pc of the Sun using data from the eROSITA all-sky survey aboard the Spectrum-Roentgen-Gamma (SRG) mission (eRASS:4). Individual spectra were normalised by exposure and distance and then stacked to produce representative averages. From these spectra, we derived characteristic X-ray luminosities, which are helpful for estimating the contribution of late-type stars to the soft, diffuse X-ray emission of the Galaxy. Results. The distance-normalised emission measures yield an average X-ray luminosity of (2.6 ± 0.1) × 1027 erg/s for M-type stars, and (15 ± 3) × 1027 erg/s for F-, G-, and K-type stars in 0.2-2.0 keV. The 10-pc average spectra could be well described by a sum of three and two thermal models. The fitted temperatures and abundances remain consistent across M-star sub-groups, while early-M stars are, surprisingly, less luminous on average than mid-to-late-M types. These results offer new insights into the collective X-ray properties of nearby stars in the volume-complete context, and provide motivation to further explore the link with the unresolved soft X-ray background of the Galaxy.

We present ultraviolet (UV) spectroscopy of the 17 Myr, G0V star HIP 67522. The UV spectrum is characterized by strong chromospheric and transition region emission lines. There was moderate spectral variability during the observations consisting of 15% stochastic fluctuation and two small flares releasing E _UV ≃ 2–4 × 10 ^32 erg in each event. We compare the broadband spectral energy distribution (SED; 4.7 Å–13.0 μ m) of the star first presented in P. C. Thao et al. to the solar SED and show that the X-ray and UV (XUV) flux density at 1 au is 10 ^2 –10 ^5 stronger (from 1000 Å down to 5 Å) in the young star compared to the present-day Sun. Attempts to reconstruct the intrinsic Ly α emission of the star failed to return physically realistic results. The discrepancy appears to arise from a population of neutral hydrogen within the system itself, extending to >±500 km s ^−1 . The absorption could be due to outflow from exoplanet atmospheric loss or from a stellar component; such a picture would require high spectral resolution observations and/or UV transit spectroscopy to confirm. Finally, we examine the evolution of the XUV emission from solar-type stars from ages of 17 Myr–9.4 Gyr and derive a scaling relation between far-UV Ly α and extreme-UV (EUV) emission as a function of stellar age. X-ray (1–100 Å) and EUV (100–911 Å) contributions to high-energy emission are 329 and 672 erg cm ^−2 s ^−1 at 1 au, respectively, suggesting that both may contribute to exoplanet heating at this epoch. The XUV emission levels at 17 Myr combined with the low density of the planet HIP 67522 b are consistent with models that predict that solar-type stars born with high rotation and activity levels will drive substantial heating and escape on close-in, gaseous planets.