Binary stars are common and have the potential to host habitable planets, which may reside in more complex habitable zones as compared to planets orbiting single stars. In this work, we use numerical simulations to assess the possibility that bright, nearby stellar multiples 36 Oph, 70 Oph, and γ Leo could host habitable planets. We find that for the 36 Oph A/B system and for the 70 Oph A/B system, the stars can support planets residing in permanently habitable zones with low ejection rates and moderate eccentricity oscillations. The habitable zones around the red giants in the γ Leo system exhibit severe dynamical instability due to the high binary eccentricity, eliminating the habitable zones around both stars. In these two systems, we find that planets in the habitable zone with orbits coplanar to that of the binary become uninhabitable due to interactions with the binary only 1.5

The discovery of a biosphere on another planet would transform how we view ourselves, and our planet Earth, in relation to the rest of the cosmos. We now know Earth is one planet among eight circling our sun; our sun is part of a swirling galaxy of over one hundred billion other suns; and our galaxy is one of untold billions in the universe. While we do not yet know how many, if any, other biospheres exist on the countless worlds orbiting countless other suns, we stand at the precipice of a new era of discovery, enabled by powerful new facilities able to peer across the light years into the atmospheres of planets similar to our own. This article is an adaptation of a science case document (SCDD) developed for the NASA Astrophysics Flagship mission the Habitable Worlds Observatory (HWO) Science, Technology, and Architecture Review Team (START) Living Worlds Community Working Group.

We present the most sensitive direct imaging search for the nearest (d = 3.2 pc) Jupiter-analog exoplanet, & varepsilon; Eri b, with JWST/NIRCam coronagraphy between 4 and 5 mu m (F444W). We achieve a 5 sigma contrast sensitivity approximate to 3.0 & times; 10(-7 )(Delta approximate to 16.3 mag) in the F444W filter at the expected planet separation of approximate to 1 ''. This is the deepest 4-5 mu m contrast performance achieved for any JWST/NIRCam observation to date at these separations (and >10 & times; better than ground-based limits). Yet, the planet remains elusive to imaging. We update the star's age to 1.1 +/- 0.1 Gyr, older than previous age estimates, using the latest gyrochronology relations. This significantly impacts & varepsilon; Eri b's inferred effective temperature (T-eff), which is now expected to lie between 150 and 200 K based on evolutionary models for a 1 M-Jup planet. Using cloud-free Sonora Flame Skimmer models and custom PICASO patchy cloud models in the above Teff range, we find that the F444W nondetection of & varepsilon; Eri b can be explained by a metal-enriched atmosphere and/or an atmosphere containing water ice clouds. Both possibilities suggest that & varepsilon; Eri b's atmosphere is strikingly similar to that of Jupiter in our solar system. Alternatively, if we do not enforce the dynamical mass (0.98 +/- 0.09 MJup), a solar metallicity, cloud-free, less than or similar to 0.81 M(Jup )planet would be consistent with the NIRCam upper limit based on the Sonora Flame Skimmer evolutionary models. Finally, we place limits on the size of a potential ring system using the NIRCam/F210M data and discuss the opportunity to directly image & varepsilon; Eri b with additional JWST observations, the Roman Coronagraph Instrument, the ExtraSolar Coronagraph on the Lazuli Observatory, and EELT/METIS.

Constraints on the masses of exoplanets directly imaged and characterized by the Habitable Worlds Observatory (HWO) are crucial for categorizing these planets and interpreting their spectra. In particular, achieving a mass measurement with a precision of approximately 10

The upcoming Roman Coronagraph will be the first high-contrast instrument in space capable of high-order wavefront sensing and control technologies, a critical technology demonstration for the proposed Habitable Worlds Observatory (HWO) that aims to directly image and characterize habitable exoEarths. The nominal Roman Coronagraph observing plan involves alternating observations of a science target and a bright, nearby reference star. High contrast is achieved using wavefront sensing and control, also known as "digging a dark hole", where performance depends on the properties of the reference star, requiring V<3, a resolved stellar diameter <2 mas, and no stellar multiplicity. The imposed brightness and diameter criteria limit the sample of reference star candidates to high-mass main sequence and post-main sequence objects, where multiplicity rates are high. A future HWO coronagraph may have similarly restrictive criteria in reference star selection. From an exhaustive literature review of 95 stars, we identify an initial list of 40 primary and 18 reserve reference star candidates relevant to both the Roman Coronagraph and HWO. We present results from an initial survey of these candidates with high-resolution adaptive optics imaging and speckle interferometry and identify no new companions. We discuss the need for higher-contrast observations to sufficiently vet these reference star candidates prior to Roman Coronagraph observations along with the implications of reference star criteria on observation planning for Roman and HWO.

Executive Summary: The Habitable Worlds Observatory (HWO) is the first astrophysics flagship mission with a key cross-divisional astrobiology science goal of searching for signs of life on rocky planets beyond our solar system. The Living Worlds Working Group under the Science, Technology, and Architecture Review Team (START) was charged with investigating how HWO could characterize potentially habitable exoplanets orbiting stars in the solar neighborhood, search for signs of life, and interpret potential biosignatures within a false positive and false negative framework. In particular, we focused on (1) identifying biosignatures that have spectral features in the UV-Vis-NIR wavelength range and defining their measurement requirements, (2) determining additional information needed from the planet and planet system to interpret biosignatures and assess the likelihood of false positives, and (3) assembling current knowledge of likely HWO target stars and identify which properties of host stars and systems are most critical to know in advance of HWO. The Living Worlds atmospheric biosignatures science case is considered one of the key drivers in the design of the observatory. An additional 10 astrobiology science cases were developed that collectively revealed key research gaps and needs required to fully explore the observatory parameter space and perform science return analyses. Investment in these research gaps will require coordination across the Science Mission Directorate and fall under the purview of the new Division-spanning astrobiology strategy.

Discovering Earth-like planets orbiting Sun-like stars was identified as a priority science goal of the Astronomy 2020 Decadal Survey. It is confounded by many factors, one of which is the high multiplicity of Sun-like stars in the local neighborhood - half of nearby Sun-like stars are in binary or higher-order stellar systems, which are less amenable to the detection of small planets with almost all of the currently productive exoplanet detection techniques. Here we describe the SHERA (Searching for Habitable Exoplanets with Relative Astrometry) NASA Small Explorer mission concept. SHERA utilizes diffractive-pupil technology on a small, simple optical space telescope to achieve microarcsecond precision relative astrometry on 14 Sun-like stars in seven nearby multi-star systems, combining the pupil and stellar binarity to provide a precise reference in the image plane. With this precision, SHERA would enable: (i) a search for rocky planets in the habitable zones of the closest Sun-like stars; (ii) an investigation of the impact of binary star formation on small, widely separated planets; and (iii) the performance of crucial precursor observations on a number of high-priority targets of NASA's future missions to characterize Earth-like planets, such as the Habitable Worlds Observatory. When combined with radial velocity measurements, SHERA relative astrometry will also enable exploration of the three-dimensional orbital structure of planets in binary systems.

Binary relative astrometry is a technique to search for rocky planets in the habitable zone of nearby binary stars using 1D relative astrometry at the microarcsecond level. This unprecedented precision would allow a custom-designed space telescope to directly measure the occurrence rate of these planets. The success of such a mission depends on our ability to recover and characterize planets from the unique format of extreme precision binary relative astrometry data. We present MARA, the Microarcsecond Astrometric Retrieval Algorithm, specifically designed for these data. We describe the design and format of the MARA pipeline, and demonstrate its accuracy and performance with a series of validation tests on simulated data, using the SHERA SMEx mission concept as an example. Our injection/recovery tests show that with these data, MARA is able to detect and characterize rocky planets in the habitable zone of alpha Cen A, down to a coplanar mass of about 1 Earth mass in 1 year orbits. Expanding to a range of input planet masses and periods for the same example mission, we find that the results from these injection/recovery tests generally agree with the analytic predictions of binary relative astrometry sensitivity. We use MARA to map out the expected completeness as a function of planet mass and period, which in this case reaches down to about 0.5 M Earth masses at 3 year orbits around alpha Cen A. These depth-of-search calculations will be a vital ingredient in demographics calculations from the final data from a binary relative astrometry mission.

A major goal of the Habitable Worlds Observatory (HWO) is to precisely characterize exoplanets and their atmospheres. However, magnetic activity from an exoplanet's host star can complicate measurements of both the stellar and planetary properties, and stellar activity can be an important factor in our interpretation of the evolutionary history of an exoplanet. In this work, we assess the extent to which magnetic activity has been characterized for potential HWO target stars by collating archival measurements of relevant observables as published in a broad range of photometric and spectroscopic datasets. We describe our data collection strategy, provide an overview of currently known activity and rotation properties in the Activity and Rotation Catalog (ARC) for potential HWO target stars, and briefly review known relationships between stellar inclination, rotation, activity, and age. Overall, we find that stellar activity (S-index and R'HK) and rotation (v sin i and Prot) properties have been measured for at least 70

Measurements of physical parameters for stars and (exo)planets are often quoted in units normalized to the Sun and/or Earth. The nominal total solar irradiance, S^ N_⊙, while based on a current best estimate with uncertainties, was adopted to be an exact reference value of 1361 W m^-2 by IAU 2015 Resolution B3, corresponding to “the mean total electromagnetic energy from the Sun, integrated over all wavelengths, incident per unit area per unit time at distance 1 au”. In the planetary and exoplanetary science literature, the units employed for “flux”, “insolation”, “instellation”, etc., are often cumbersome or inconsistent. To simplify the quoting of irradiance units for astronomical applications, we introduce the portmanteau solirad, short for solar irradiance, as an abbreviated version of the longer IAU term “nominal total solar irradiance”. The solirad (So) is a unit of irradiance, where 1 solirad = 1 So = 1361 W m^-2, equivalent to the IAU nominal total solar irradiance, and to an apparent bolometric magnitude of m_bol = -26.832 mag (per IAU 2015 Resolution B2).

WISPIT 2 is a nearby young star with a multiringed disk that was recently confirmed to host a similar to 4.9 MJup gas giant planet embedded in a large (60 au) gap at a radial separation of 57 au from the host star. We confirm and characterize a second, close-in planet in the WISPIT 2 system using a combination of new Very Large Telescope/SPHERE H-band dual-polarization imaging and VLTI/GRAVITY K-band interferometric observations of the WISPIT 2 system. The GRAVITY detection is consistent with a point-like source while its extracted K-band spectrum shows CO band-head absorption at 2.3 mu m and a continuum shape consistent with a young giant planet. From the GRAVITY data, we extract a medium resolution K-band spectrum of the companion and fit atmospheric model grids using the species tool with nested sampling to constrain its effective temperature, radius, and luminosity. We infer Teff of 1500-2600 K, a radius of 0.91-2.2 RJup, and a luminosity of (-3.47)-(-3.63). Comparison with evolutionary tracks implies a mass range of 8-12 MJup, approximately twice as massive as the previously confirmed WISPIT 2b. The astrometry rules out a background source and marginally detects orbital motion of WISPIT 2 c, which needs further follow-up observations for confirmation. WISPIT 2 now becomes an analog to PDS 70, offering a second laboratory for studying the formation and early evolution of a multiplanet system within its natal disk.

The near-ultraviolet (NUV) wavelength range contains a valuable ozone absorption feature for characterizing the atmospheric composition of Earth-like exoplanets. Both the LUVOIR and HabEx decadal mission concept studies baseline instrumentation for obtaining photometry of directly imaged exoplanets down to wavelengths of 200 nm. Both of their proposed implementations present challenges: in the case of the HabEx starshade occulter, a separate spacecraft is required; in the case of a NUV channel within the main coronagraph instrument, non-UV-optimized optics limit the performance. However, the science requirements allow the relaxation of some of the trades of a dedicated near-UV coronagraph. For instance, given that the inner working angle (IWA) of the coronagraph is a function of the wavelength, and one would only consider the characterization of planets detected in the visible, the IWA of the NUV coronagraph can be relaxed to meet the IWA of the visible coronagraph. In addition, given that a NUV coronagraph would be used for a follow-up observation after a visible detection, it could be designed to produce a half dark zone, allowing the simplification of the optical design. Here, we present the case for a standalone NUV coronagraph instrument for the Habitable Worlds Observatory based on the science requirements, developed as part of the Coronagraph Technology Roadmap study commissioned by NASA's Exoplanet Exploration Office. We describe the trades and rationale behind the recommendation of having a separate NUV coronagraph instrument and show the evaluation of several coronagraph designs in the NUV. We assess the effect of polarization aberrations, discuss relevant technologies, and describe potential NUV detectors and wavefront sensing and control strategies.

Context . The multitude of different architectures found for evolved exoplanet systems are in all likelihood set during the initial planet-formation phase in the circumstellar disk. To understand this process, we have to study the earliest phases of planet formation. Aims . Complex sub-structures, believed to be driven by embedded planets, have been detected in a significant portion of the disks observed at high angular resolution. We aim to extend the sample of such disks to low stellar masses and to connect the disk morphology to the expected proto-planet properties. Methods . In this study, we used VLT/SPHERE to obtain resolved images on the scale of ∼10 au of the circumstellar disk in the 2MASSJ16120668-3010270 system in polarized scattered light. We searched for the thermal radiation of recently formed gas giants embedded in the disk. Additionally, we used VLT/XSHOOTER to obtain the stellar properties in the system. Results . We resolve the disk in the 2MASSJ16120668-3010270 system for the first time in scattered near-infrared light and reveal an exceptionally structured disk. We find an inner disk (reaching out to 40 au) with two spiral arms, separated by a gap from an outer ring extending to 115 au. By comparison with our own model and hydrodynamic models from the literature, we find that these structures are consistent with the presence of an embedded gas giant with a mass range between 0.1 M Jup and 5 M Jup depending on the employed model and their underlying assumptions. Our SPHERE observations find a tentative candidate point source within the disk gap, the brightness of which would be consistent with this mass range if it indeed traces thermal emission by an embedded planet. This interpretation is somewhat strengthened by the proximity of this signal to compact millimeter continuum emission in the disk gap, which may trace circumplanetary material. It is, however, unclear if this tentative companion candidate could be responsible for the observed disk gap size, given its close proximity to the inner disk. Generally, our VLT/SPHERE observations set an upper limit of ∼5 M Jup in the disk gap (∼0.2”−0.5”), consistently with our modeling results. The 2MASSJ16120668-3010270 system is one of only a few systems that shows this exceptional morphology of spiral arms located inside a scattered light gap and ring. We speculate that this may have to do with a higher disk viscosity compared with other systems such as PDS 70. If planets in the disk are confirmed, 2MASSJ16120668-3010270 will become a prime laboratory for the study of planet-disk interaction.

Magnetic chemically peculiar (mCP) stars are strongly magnetic upper main-sequence stars that exhibit light rotational variability due to an uneven surface distribution of certain peculiar elements, which may appear in phase at certain wavelengths and in antiphase to the flux at other wavelengths. We present a study of the properties of photometric variability of a sample of confirmed mCP stars (mostly Ap/CP2 stars), mCP star candidates, and several non-CP stars in the near ultraviolet and visible wavelength regions based on observational data from the GALEX and Kepler prime missions. Antiphase variations between the near ultraviolet and optical light curves are observed in the majority of mCP stars. We investigate the presence of a correlation of the variability amplitudes in both wavelength regions with effective temperature, surface gravity, and metallicity and calculate model atmospheres, spectral energy distributions and synthetic light curves to connect our findings to theoretical models. While the theoretical calculations show that, at fixed abundances, a clear correlation between the light curve amplitude ratios and effective temperature is expected, our sample does not show any correlation with the investigated properties. This may be due to the highly individualistic abundance patterns of our sample stars, which are the main contributors to the line blanketing in different wavelength bands.

We assess archival high-energy data for key stars on the Habitable Worlds Observatory (HWO) Target Stars and Systems 2025 list, as stellar radiation is critical to shaping and interpreting planetary atmospheres. Using a sample of 98 nearby stars (HWO Tier 1 targets), we compile and evaluate X-ray and ultraviolet (UV) data from archival eROSITA, Chandra, XMM-Newton, RÖentgen SATellite, Extreme-Ultraviolet Explorer, Swift, Far Ultraviolet Spectroscopic Explorer, International Ultraviolet Explorer (IUE), Galaxy Evolution Explorer, and Hubble Space Telescope (HST). We examine spectral and temporal coverage, assess data quality, and identify major gaps. UV data are moderately available, with most coverage coming from near-UV spectra from IUE. Far fewer stars have far-UV spectra, especially from HST. In the X-ray regime, some stars have high-quality spectra, while others are limited to shallow detections or broadband photometry. A small fraction of the sample has both X-ray and UV spectra of sufficient quality to support full spectral energy distribution modeling. Truly comprehensive coverage across X-ray, extreme-UV, and both UV bands remains extremely rare. Most data sets are single-epoch, limiting assessments of variability and flares—key factors in atmospheric photochemistry and escape. Moreover, the lack of simultaneous or contemporaneous observations across bands adds further uncertainty. Our findings underscore the need for new space-based missions and coordinated multiwavelength campaigns, ideally with overlapping coverage, to improve stellar characterization for HWO. As several key observatories age and face potential decommissioning, there is a narrow window of opportunity to secure these critical data. Investing in this effort now will directly support the science goals of HWO and enhance future studies of planetary habitability.

Context. Wide separation gas giant planets present a challenge to current planet formation theories, and the detection and characterisation of these systems enables us to constrain their formation pathways. Aims. The WIde Separation Planets In Time (WISPIT) survey aims to detect and characterise wide separation planetary-mass companions over a range of ages from <5 to 20 Myr around solar-type host stars at distances of 75-500 (median 140) parsecs. Methods. The WISPIT survey carries out two five-minute H-band exposures with the VLT/SPHERE instrument and IRDIS camera separated by at least six months to identify co-moving companions via proper motion analysis. These two H-band observations in combination with a follow-up K-s-band observation were used to determine the colour and magnitude of the co-moving companions and to derive their masses through comparison to AMES-COND and AMES-DUSTY evolutionary tracks. Results. We report the discovery of WISPIT 1b and WISPIT 1c, two gas giant exoplanets that are co-moving with the stellar binary WISPIT 1, which itself consists of a K4 star and M5.5 star in a multi-decadal orbit. The planets are at projected separations of 338 au and 840 au and have masses of 10 M-J and 4 M-J, respectively. Conclusions. We identified two common proper motion planetary companions of a (previously unknown) stellar binary with a Sunlike primary. These targets are ideal for follow-up characterisation with both ground- and space-based telescopes. Monitoring of the orbit with the GRAVITY interferometer will place constraints on their eccentricity, and spectroscopic characterisation will identify the composition and metallicity, providing information on their formation pathways.

Context. Directly imaged exoplanets in wide orbits pose a challenge to current gas giant formation theories, as they need to form quickly and acquire enough material before the disc dissipates. These processes cannot be accommodated by in situ formation models based on core accretion. Aims. We searched for wide separation (>100 au) planetary-mass companions with the Young Suns Exoplanet Survey (YSES). In this work, we present a planetary-mass candidate companion discovered as part of the survey. Methods. We conducted follow-up observations of the candidate system after the first-epoch observations and obtained six epochs of observations for the candidate system between 2018 and 2024, along with the integral field spectroscopy of the stellar component. Results. We report the detection of a candidate companion with H = 22.04 +/- 0.13 mag at a projected separation of 730 +/- 10 au from the primary star. High-angular-resolution-imaging observations of the central star show it is a visual binary. The acceleration data, orbital fitting, spectral energy distribution fitting, and radial velocity differences all suggest that there is at least one more unresolved low-mass stellar companion in this system. The planetary-mass candidate shows a significant proper motion comparable to that of the primary star. We have estimated an age of 19-28 Myr for the primary star. We cannot confirm the companionship of the candidate due to the unknown barycentre of the stars. Conclusions. Long-term imaging and radial velocity monitoring of the central stars, along with spectroscopy of the candidate companion, are key to resolving the nature of this system. If confirmed, the candidate companion would be characterised by a mass of 3-5 M-J estimated with the ATMO evolutionary model. It would be another cold, low-mass planet resembling 51 Eri b and AF Lep b. Its extremely wide separation from the host star would challenge the formation theory of gas giant exoplanets.

We report the discovery and confirmation of TOI-4465 b, a 1.25 R J − 0.07 R J + 0.08 R J , 5.89 M J ± 0.26 M J giant planet orbiting a G dwarf star at d ≃ 122 pc. The planet was detected as a single-transit event in data from Sector 40 of the Transiting Exoplanet Survey Satellite (TESS) mission. Radial velocity (RV) observations of TOI-4465 showed a planetary signal with an orbital period of ∼102 days and an orbital eccentricity of e = 0.24 ± 0.01. TESS reobserved TOI-4465 in Sector 53 and Sector 80 but did not detect another transit of TOI-4465 b, as the planet was not expected to transit during these observations based on the RV period. A global ground-based photometry campaign was initiated to observe another transit of TOI-4465 b after the RV period determination. The ∼12 hr long transit event was captured from multiple sites around the world and included observations from 24 citizen scientists, confirming the orbital period as ∼102 days. TOI-4465 b is a relatively dense (3.73 ± 0.53 g cm −3 ), temperate (375–478 K) giant planet. Based on giant planet structure models, TOI-4465 b appears to be enriched in heavy elements at a level consistent with late-stage accretion of icy planetesimals. Additionally, we explore TOI-4465 b’s potential for atmospheric characterization and obliquity measurement. Increasing the number of long-period planets by confirming single-transit events is crucial for understanding the frequency and demographics of planet populations in the outer regions of planetary systems.

In the past decades, several thousand exoplanet systems have been discovered around evolved, main-sequence stars, revealing a wide diversity in their architectures. To understand how the planet formation process can lead to vastly different outcomes in system architecture, we have to study the starting conditions of planet formation within the disks around young stars. In this study, we are presenting high-resolution direct imaging observations with the Very Large Telescope/SPHERE of the young (similar to 5 Myr), nearby (similar to 133 pc), solar-analog designated as WISPIT 2 (= TYC 5709-354-1). These observations were taken as part of our survey program that explores the formation and orbital evolution of wide-separation gas giants. WISPIT 2 was observed in four independent epochs using polarized light and total intensity observations. They reveal for the first time an extended (380 au) disk in scattered light with a multi-ringed substructure. We directly detect a young protoplanet, WISPIT 2b, embedded in a disk gap and show that it is comoving with its host star. Multiple SPHERE epochs demonstrate that it shows orbital motion consistent with Keplerian motion in the observed disk gap. Our H- and Ks-band photometric data are consistent with thermal emission from a young planet. By comparison with planet evolutionary models, we find a mass of the planet of 4.9-0.6+0.9 MJup. This mass is also consistent with the width of the observed disk gap, retrieved from hydrodynamic models. WISPIT 2b is the first unambiguous planet detection in a multi-ringed disk, making the WISPIT 2 system the ideal laboratory to study planet-disk interaction and subsequent evolution.

The IAU-Working Group on Star Names consists of scholars with a huge diversity of cultural backgrounds. In our monthly discussions of cultural names from different places and times, this year we came across some interesting facts in intercultural comparisons. In particular, the constellation of Andromeda was depicted as the Syriac goddess Derketo in early al-Sufi manuscripts, the 'Horse'-constellations of the Arabic, Babylonian, Greek and Indian culture are in the same area of the sky (around modern Pegasus) which invites studying possible cultural transfer. Another interesting coincidence is that the Greek asterism of the 'Manger' is at the same place as the Vedic 'Nourisher'. Furthermore, we found that one of the so-called ancient Greek globes (from Gal & eacute;rie Kugel in Paris) is actually Indian with Chinese and Persian influences, so likely dates to the so-called 'Greek period' in Indian art and astronomy. Technically, we announce the long-term venture of the 'All Skies Encyclopaedia' (ASE) and our 'Naked Eye Star Catalog' (NEC) which might be useful for all sorts of historical studies.