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Black hole binary systems with companion stars are typically found via their x-ray emission, generated by interaction and accretion. Noninteracting binaries are expected to be plentiful in the Galaxy but must be observed using other methods. We combine radial velocity and photometric variability data to show that the bright, rapidly rotating giant star 2MASS J05215658+4359220 is in a binary system with a massive unseen companion. The system has an orbital period of ~83 days and near-zero eccentricity. The photometric variability period of the giant is consistent with the orbital period, indicating star spots and tidal synchronization. Constraints on the giant’s mass and radius imply that the unseen companion is 3.3 − 0.7 + 2.8 solar masses, indicating that it is a noninteracting low-mass black hole or an unexpectedly massive neutron star.

We report the detection of a planet whose orbit surrounds a pair of low-mass stars. Data from the Kepler spacecraft reveal transits of the planet across both stars, in addition to the mutual eclipses of the stars, giving precise constraints on the absolute dimensions of all three bodies. The planet is comparable to Saturn in mass and size and is on a nearly circular 229-day orbit around its two parent stars. The eclipsing stars are 20 and 69% as massive as the Sun and have an eccentric 41-day orbit. The motions of all three bodies are confined to within 0.5° of a single plane, suggesting that the planet formed within a circumbinary disk.

An Earth-sized planet is observed orbiting a nearby star within the liquid-water, habitable zone, the atmospheric composition of which could be determined from future observations. Super-Earth rocks around cool star Planets cause a dip in the light received when they pass in front of their parent stars. M stars have masses less than 60 per cent that of the Sun, and account for three-quarters of our Galaxy's stellar population. Seven Earth-sized planets are known to transit such a star, TRAPPIST-1, at 12 parsecs from Earth, but their masses and therefore their densities are rather poorly constrained. Jason Dittman et al . report observations of LHS 1140b, a planet with a radius 1.4 times that of Earth that is transiting an M dwarf star 12 parsecs from Earth and receiving sufficient insolation to place it in the liquid-water, 'habitable zone'. They measure the mass to be 6.6 times that of Earth, which suggests a rocky bulk composition. M dwarf stars, which have masses less than 60 per cent that of the Sun, make up 75 per cent of the population of the stars in the Galaxy 1 . The atmospheres of orbiting Earth-sized planets are observationally accessible via transmission spectroscopy when the planets pass in front of these stars 2 , 3 . Statistical results suggest that the nearest transiting Earth-sized planet in the liquid-water, habitable zone of an M dwarf star is probably around 10.5 parsecs away 4 . A temperate planet has been discovered orbiting Proxima Centauri, the closest M dwarf 5 , but it probably does not transit and its true mass is unknown. Seven Earth-sized planets transit the very low-mass star TRAPPIST-1, which is 12 parsecs away 6 , 7 , but their masses and, particularly, their densities are poorly constrained. Here we report observations of LHS 1140b, a planet with a radius of 1.4 Earth radii transiting a small, cool star (LHS 1140) 12 parsecs away. We measure the mass of the planet to be 6.6 times that of Earth, consistent with a rocky bulk composition. LHS 1140b receives an insolation of 0.46 times that of Earth, placing it within the liquid-water, habitable zone 8 . With 90 per cent confidence, we place an upper limit on the orbital eccentricity of 0.29. The circular orbit is unlikely to be the result of tides and therefore was probably present at formation. Given its large surface gravity and cool insolation, the planet may have retained its atmosphere despite the greater luminosity (compared to the present-day) of its host star in its youth 9 , 10 . Because LHS 1140 is nearby, telescopes currently under construction might be able to search for specific atmospheric gases in the future 2 , 3 .

Whereas large planets, such as gas giants, are more likely to form around high-metallicity stars, terrestrial-sized planets are found to form around stars with a wide range of metallicities, indicating that they may be widespread in the disk of the Galaxy. Exoplanets around metal-poor stars A key discovery of the past decade in the field of exoplanet research was the realization that stars of high metallicity are those most likely to harbour giant exoplanets, supporting the model in which planets form by the accumulation of dust and ice particles. Whether the planet–metallicity correlation holds for terrestrial planets remained unclear, but the Kepler mission's discovery last year of hundreds of small exoplanet candidates provided an opportunity to find out. The spectroscopic metallicities of the host stars of 226 small exoplanet candidates have now been determined. The smaller ones, of less than four Earth radii, were found around stars with a wide range of metallicities, on average close to that of the Sun. Larger planets were more common around stars of high metallicity. These findings suggest that terrestrial planets may be widespread in the disk of the Galaxy, with no special requirement of enhanced metallicity for their formation. The abundance of heavy elements (metallicity) in the photospheres of stars similar to the Sun provides a ‘fossil’ record of the chemical composition of the initial protoplanetary disk. Metal-rich stars are much more likely to harbour gas giant planets 1 , 2 , 3 , 4 , supporting the model that planets form by accumulation of dust and ice particles 5 . Recent ground-based surveys suggest that this correlation is weakened for Neptunian-sized planets 4 , 6 , 7 , 8 , 9 . However, how the relationship between size and metallicity extends into the regime of terrestrial-sized exoplanets is unknown. Here we report spectroscopic metallicities of the host stars of 226 small exoplanet candidates discovered by NASA’s Kepler mission 10 , including objects that are comparable in size to the terrestrial planets in the Solar System. We find that planets with radii less than four Earth radii form around host stars with a wide range of metallicities (but on average a metallicity close to that of the Sun), whereas large planets preferentially form around stars with higher metallicities. This observation suggests that terrestrial planets may be widespread in the disk of the Galaxy, with no special requirement of enhanced metallicity for their formation.

The giant planet KELT-9b has a dayside temperature of about 4,600 K, which is sufficiently high to dissociate molecules and to evaporate its atmosphere, owing to its hot stellar host. Hot Jupiter-like exoplanet Hot Jupiters are exoplanets that are physically similar to Jupiter, but are strongly irradiated by their host stars. Until now, the most extreme example was WASP-33b, but its atmosphere is still cool enough to contain molecules. Scott Gaudi et al . report the discovery of KELT-9b, which has a dayside temperature of about 4,600 kelvin. This is sufficiently high to dissociate molecules, so the primary sources of opacity in the dayside atmosphere of KELT-9b are probably atomic metals. The atmosphere might be evaporated before the host star reaches the end of its life. The amount of ultraviolet irradiation and ablation experienced by a planet depends strongly on the temperature of its host star. Of the thousands of extrasolar planets now known, only six have been found that transit hot, A-type stars (with temperatures of 7,300–10,000 kelvin), and no planets are known to transit the even hotter B-type stars. For example, WASP-33 is an A-type star with a temperature of about 7,430 kelvin, which hosts the hottest known transiting planet, WASP-33b (ref. 1 ); the planet is itself as hot as a red dwarf star of type M (ref. 2 ). WASP-33b displays a large heat differential between its dayside and nightside 2 , and is highly inflated–traits that have been linked to high insolation 3 , 4 . However, even at the temperature of its dayside, its atmosphere probably resembles the molecule-dominated atmospheres of other planets and, given the level of ultraviolet irradiation it experiences, its atmosphere is unlikely to be substantially ablated over the lifetime of its star. Here we report observations of the bright star HD 195689 (also known as KELT-9), which reveal a close-in (orbital period of about 1.48 days) transiting giant planet, KELT-9b. At approximately 10,170 kelvin, the host star is at the dividing line between stars of type A and B, and we measure the dayside temperature of KELT-9b to be about 4,600 kelvin. This is as hot as stars of stellar type K4 (ref. 5 ). The molecules in K stars are entirely dissociated, and so the primary sources of opacity in the dayside atmosphere of KELT-9b are probably atomic metals. Furthermore, KELT-9b receives 700 times more extreme-ultraviolet radiation (that is, with wavelengths shorter than 91.2 nanometres) than WASP-33b, leading to a predicted range of mass-loss rates that could leave the planet largely stripped of its envelope during the main-sequence lifetime of the host star 6 .

Cold Jovian planets play an important role in sculpting the dynamical environment in which inner terrestrial planets form. The core accretion model predicts that giant planets cannot form around low-mass M dwarfs, although this idea has been challenged by recent planet discoveries. Here, we investigate the occurrence rate of giant planets around low-mass (0.1-0.3M\\(_\\odot\\)) M dwarfs. We monitor a volume-complete, inactive sample of 200 such stars located within 15 parsecs, collecting four high-resolution spectra of each M dwarf over six years and performing intensive follow-up monitoring of two candidate radial-velocity variables. We use TRES on the 1.5 m telescope at the Fred Lawrence Whipple Observatory and CHIRON on the Cerro Tololo Inter-American Observatory 1.5 m telescope for our primary campaign, and MAROON-X on Gemini North for high-precision follow-up. We place a 95%-confidence upper limit of 1.5% (68%-confidence limit of 0.57%) on the occurrence of \\(M_{\\rm P}\\)sin\\(i > \\)1M\\(_{\\rm J}\\) giant planets out to the water snow line and provide additional constraints on the giant planet population as a function of \\(M_{\\rm P}\\)sin\\(i\\) and period. Beyond the snow line (\\(100\\) K \\(< T_{\\rm eq} < 150\\) K), we place 95%-confidence upper limits of 1.5%, 1.7%, and 4.4% (68%-confidence limits of 0.58%, 0.66%, and 1.7%) for 3M\\(_{\\rm J} < M_{\\rm P}\\)sin\\(i < 10\\)M\\(_{\\rm J}\\), 0.8M\\(_{\\rm J} < M_{\\rm P}\\)sin\\(i < 3\\)M\\(_{\\rm J}\\), and 0.3M\\(_{\\rm J} < M_{\\rm P}\\)sin\\(i < 0.8\\)M\\(_{\\rm J}\\) giant planets; i.e., Jupiter analogs are rare around low-mass M dwarfs. In contrast, surveys of Sun-like stars have found that their giant planets are most common at these Jupiter-like instellations.

The present study reports the confirmation of BD-14 3065b, a transiting planet/brown dwarf in a triple-star system, with a mass near the deuterium burning boundary. BD-14 3065b has the largest radius observed within the sample of giant planets and brown dwarfs around post-main-sequence stars. Its orbital period is 4.3 days, and it transits a subgiant F-type star with a mass of \\(M_\\star=1.41 \\pm 0.05 M_{\\odot}\\), a radius of \\(R_\\star=2.35 \\pm 0.08 R_{\\odot}\\), an effective temperature of \\(T_{\\rm eff}=6935\\pm90\\) K, and a metallicity of \\(-0.34\\pm0.05\\) dex. By combining TESS photometry with high-resolution spectra acquired with the TRES and Pucheros+ spectrographs, we measured a mass of \\(M_p=12.37\\pm0.92 M_J\\) and a radius of \\(R_p=1.926\\pm0.094 R_J\\). Our discussion of potential processes that could be responsible for the inflated radius led us to conclude that deuterium burning is a plausible explanation resulting from the heating of BD-14 3065b's interior. Detection of the secondary eclipse with TESS photometry enables a precise determination of the eccentricity \\(e_p=0.066\\pm0.011\\) and reveals BD-14 3065b has a brightness temperature of \\(3520 \\pm 130\\) K. With its unique characteristics, BD-14 3065b presents an excellent opportunity to study its atmosphere through thermal emission spectroscopy.

Irradiated Jovian atmospheres are complex, dynamic, and can undergo temporal variations due to the close proximity of their parent stars. Of the Jovian planets that have been catalogued to date, KELT-9b is the hottest Gas Giant known, with an equilibrium temperature of 4050 K. We probe the temporal variability of transmission spectroscopic signatures from KELT-9b via a set of archival multi-year ground-based transit observations, performed with the TRES facility on the 1.5 m reflector at the Fred Lawrence Whipple Observatory. Our observations confirm past detections of Fe I, Fe II and Mg I over multiple epochs, in addition to excess absorption at H-alpha, which is an indicator for ongoing mass-loss. From our multi-year dataset, the H-alpha light curve consistently deviates from a standard transit, and follows a 'W' shape that is deeper near ingress and egress, and shallower mid-transit. To search for and quantify any seasonal variations that may be present, we parameterise a 'cometary tail' model to fit for the H-alpha transit. We find no detectable variations between the different observed epochs. Though a 'cometary tail' describes the H-alpha flux variations well, we note that such a scenario requires a high density of neutral hydrogen in the n = 2 excited state far beyond the planetary atmosphere. Other scenarios, such as centre-to-limb variations larger than that expected from 1-D atmosphere models, may also contribute to the observed H-alpha transit shape. These multi-epoch observations highlight the capabilities of small telescopes to provide temporal monitoring of the dynamics of exoplanet atmospheres.

We present here a validation of sub-Saturn exoplanet TOI-181b orbiting a K spectral type star TOI-181 (Mass: 0.822 \\(\\pm\\) 0.04 M\\(_{\\odot}\\), Radius: 0.745 \\(\\pm\\) 0.02 R\\(_{\\odot}\\), Temperature: 4994 \\(\\pm\\) 50 K) as a part of Validation of Transiting Exoplanets using Statistical Tools (VaTEST) project. TOI-181b is a planet with radius 6.95 \\(\\pm\\) 0.08 R\\(_{\\oplus}\\), mass 46.16 \\(\\pm\\) 2.71 M\\(_{\\oplus}\\), orbiting in a slightly eccentric orbit with eccentricity 0.15 \\(\\pm\\) 0.06 and semi-major axis of 0.054 \\(\\pm\\) 0.004 AU, with an orbital period of 4.5320 \\(\\pm\\) 0.000002 days. The transit photometry data was collected using Transiting Exoplanet Survey Satellite (TESS) and spectroscopic data for radial velocity analysis was collected using The European Southern Observatory's (ESO) High Accuracy Radial Velocity Planet Searcher (HARPS) telescope. Based on the radial velocity best-fit model we measured RV semi-amplitude to be 20.56 \\(\\pm\\) 2.37 m s\\(^{-1}\\). Additionally, we used \\texttt{VESPA} and \\texttt{TRICERATOPS} to compute the False Positive Probability (FPP), and the findings were FPP values of \\(1.68\\times10^{-14}\\) and \\(3.81\\times10^{-04}\\), respectively, which are significantly lower than the 1% threshold. The finding of TOI-181b is significant in the perspective of future work on the formation and migration history of analogous planetary systems since warm sub-Saturns are uncommon in the known sample of exoplanets.

We present the discovery of the Type II supernova SN 2023ixf in M101 and follow-up photometric and spectroscopic observations, respectively, in the first month and week of its evolution. Our discovery was made within a day of estimated first light, and the following light curve is characterized by a rapid rise (\\(\\approx5\\) days) to a luminous peak (\\(M_V\\approx-18.2\\) mag) and plateau (\\(M_V\\approx-17.6\\) mag) extending to \\(30\\) days with a fast decline rate of \\(\\approx0.03\\) mag day\\(^{-1}\\). During the rising phase, \\(U-V\\) color shows blueward evolution, followed by redward evolution in the plateau phase. Prominent flash features of hydrogen, helium, carbon, and nitrogen dominate the spectra up to \\(\\approx5\\) days after first light, with a transition to a higher ionization state in the first \\(\\approx2\\) days. Both the \\(U-V\\) color and flash ionization states suggest a rise in the temperature, indicative of a delayed shock breakout inside dense circumstellar material (CSM). From the timescales of CSM interaction, we estimate its compact radial extent of \\(\\sim(3-7)\\times10^{14}\\) cm. We then construct numerical light-curve models based on both continuous and eruptive mass-loss scenarios shortly before explosion. For the continuous mass-loss scenario, we infer a range of mass-loss history with \\(0.1-1.0\\,M_\\odot\\,{\\rm yr}^{-1}\\) in the final \\(2-1\\) yr before explosion, with a potentially decreasing mass loss of \\(0.01-0.1\\,M_\\odot\\,{\\rm yr}^{-1}\\) in \\(\\sim0.7-0.4\\) yr toward the explosion. For the eruptive mass-loss scenario, we favor eruptions releasing \\(0.3-1\\,M_\\odot\\) of the envelope at about a year before explosion, which result in CSM with mass and extent similar to the continuous scenario. We discuss the implications of the available multiwavelength constraints obtained thus far on the progenitor candidate and SN 2023ixf to our variable CSM models.