More Like this

1. An Adaptive Optics Census of Companions to Northern Stars Within 25 pc with Robo-AO

   https://doi.org/10.3847/1538-3881/ac53fc  

   Salama, Maïssa ; Ziegler, Carl ; Baranec, Christoph ; Liu, Michael C. ; Law, Nicholas M. ; Riddle, Reed ; Henry, Todd J. ; Winters, Jennifer G. ; Jao, Wei-Chun ; Ou, James ; et al ( April 2022 , The Astronomical Journal)

   In order to assess the multiplicity statistics of stars across spectral types and populations in a volume-limited sample, we censused nearby stars for companions with Robo-AO. We report on observations of 1157 stars of all spectral types within 25 pc with decl. >−13° searching for tight companions. We detected 154 companion candidates with separations ranging from ∼0.″15 to 4.″0 and magnitude differences up to Δm${}_{i\prime }\le 7$using the robotic adaptive optics instrument Robo-AO. We confirmed physical association from Gaia EDR3 astrometry for 53 of the companion candidates, 99 remain to be confirmed, and two were ruled out as background objects. We complemented the high-resolution imaging companion search with a search for comoving objects with separations out to 10,000 au in Gaia EDR3, which resulted in an additional 147 companions registered. Of the 301 total companions reported in this study, 49 of them are new discoveries. Out of the 191 stars with significant acceleration measurements in the Hipparcos–Gaia catalog of accelerations, we detect companions around 115 of them, with the significance of the acceleration increasing as the companion separation decreases. From this survey, we report the following multiplicity fractions (compared to literature values): 40.9% ± 3.0% (44%) formore »FGK stars and 28.2% ± 2.3% (27%) for M stars, as well as higher-order fractions of 5.5% ± 1.1% (11%) and 3.9% ± 0.9% (5%) for FGK stars and M-type stars, respectively.

   « less
2. The VLA/ALMA Nascent Disk And Multiplicity (VANDAM) Survey of Orion Protostars. V. A Characterization of Protostellar Multiplicity

   https://doi.org/10.3847/1538-4357/ac36d2  

   Tobin, John J. ; Offner, Stella S. R. ; Kratter, Kaitlin M. ; Megeath, S. Thomas ; Sheehan, Patrick D. ; Looney, Leslie W. ; Diaz-Rodriguez, Ana Karla ; Osorio, Mayra ; Anglada, Guillem ; Sadavoy, Sarah I. ; et al ( January 2022 , The Astrophysical Journal)

   We characterize protostellar multiplicity in²⁰

   Current address: Niels Bohr Institute, University of Copenhagen, Øster Voldgade 5–7, DK-1350, Copenhagen K, Denmark.

   the Orion molecular clouds using Atacama Large Millimeter/submillimeter Array 0.87 mm and Very Large Array 9 mm continuum surveys toward 328 protostars. These observations are sensitive to projected spatial separations as small as ∼20 au, and we consider source separations up to 10⁴au as potential companions. The overall multiplicity fraction (MF) and companion fraction (CF) for the Orion protostars are 0.30 ± 0.03 and 0.44 ± 0.03, respectively, considering separations from 20 to 10⁴au. The MFs and CFs are corrected for potential contamination by unassociated young stars using a probabilistic scheme based on the surface density of young stars around each protostar. The companion separation distribution as a whole is double peaked and inconsistent with the separation distribution of solar-type field stars, while the separation distribution of Flat Spectrum protostars is consistent solar-type field stars. The multiplicity statistics and companion separation distributions of the Perseus star-forming region are consistent with those of Orion. Based on the observed peaks in the Class 0 separations at ∼100 au and ∼10³au, we argue that multiples with separations <500 au are likely produced bymore »both disk fragmentation and turbulent fragmentation with migration, and those at ≳10³au result primarily from turbulent fragmentation. We also find that MFs/CFs may rise from Class 0 to Flat Spectrum protostars between 100 and 10³au in regions of high young stellar object density. This finding may be evidence for the migration of companions from >10³au to <10³au, and that some companions between 10³and 10⁴au must be (or become) unbound.

   « less
3. The POKEMON Speckle Survey of Nearby M Dwarfs. I. New Discoveries

   https://doi.org/10.3847/1538-3881/ac739c  

   Clark, Catherine A. ; van Belle, Gerard T. ; Horch, Elliott P. ; von Braun, Kaspar ; Ciardi, David R. ; Winters, Jennifer G. ; Kiman, Rocio ( July 2022 , The Astronomical Journal)

   M dwarfs are favorable targets for exoplanet detection with current instrumentation, but stellar companions can induce false positives and inhibit planet characterization. Knowledge of stellar companions is also critical to our understanding of how binary stars form and evolve. We have therefore conducted a survey of stellar companions around nearby M dwarfs, and here we present our new discoveries. Using the Differential Speckle Survey Instrument at the 4.3 m Lowell Discovery Telescope, and the similar NN-EXPLORE Exoplanet Stellar Speckle Imager at the 3.5 m WIYN telescope, we carried out a volume-limited survey of M-dwarf multiplicity to 15 parsecs, with a special emphasis on including the later M dwarfs that were overlooked in previous surveys. Additional brighter targets at larger distances were included for a total sample size of 1070 M dwarfs. Observations of these 1070 targets revealed 26 new companions; 22 of these systems were previously thought to be single. If all new discoveries are confirmed, then the number of known multiples in the sample will increase by 7.6%. Using our observed properties, as well as the parallaxes and 2MASSKmagnitudes for these objects, we calculate the projected separation, and estimate the mass ratio and component spectral types, for thesemore »systems. We report the discovery of a new M-dwarf companion to the white dwarf Wolf 672 A, which hosts a known M-dwarf companion as well, making the system trinary. We also examine the possibility that the new companion to 2MASS J13092185-2330350 is a brown dwarf. Finally, we discuss initial insights from the POKEMON survey.

   « less
4. SDSS IV MaNGA: visual morphological and statistical characterization of the DR15 sample

   https://doi.org/10.1093/mnras/stac635  

   Vázquez-Mata, J. A. ; Hernández-Toledo, H. M. ; Avila-Reese, V. ; Herrera-Endoqui, M. ; Rodríguez-Puebla, A. ; Cano-Díaz, M. ; Lacerna, I. ; Martínez-Vázquez, L. A. ; Lane, R. ( March 2022 , Monthly Notices of the Royal Astronomical Society)

   We present a detailed visual morphological classification for the 4614 MaNGA galaxies in SDSS Data Release 15, using image mosaics generated from a combination of r band (SDSS and deeper DESI Legacy Surveys) images and their digital post-processing. We distinguish 13 Hubble types and identify the presence of bars and bright tidal debris. After correcting the MaNGA sample for volume completeness, we calculate the morphological fractions, the bi-variate distribution of type and stellar mass M* – where we recognize a morphological transition ‘valley’ around S0a-Sa types – and the variations of the g − i colour and luminosity-weighted age over this distribution. We identified bars in 46.8 per cent of galaxies, present in all Hubble types later than S0. This fraction amounts to a factor ∼2 larger when compared with other works for samples in common. We detected 14 per cent of galaxies with tidal features, with the fraction changing with M* and morphology. For 355 galaxies, the classification was uncertain; they are visually faint, mostly of low/intermediate masses, low concentrations, and discy in nature. Our morphological classification agrees well with other works for samples in common, though some particular differences emerge, showing that our image procedures allow us to identify a wealthmore »of added value information as compared to SDSS-based previous estimates. Based on our classification, we also propose an alternative criteria for the E–S0 separation, in the structural semimajor to semiminor axis versus bulge to total light ratio (b/a − B/T) and concentration versus semimajor to semiminor axis (C − b/a) space.

   « less
5. A Close-in Puffy Neptune with Hidden Friends: The Enigma of TOI 620

   https://doi.org/10.3847/1538-3881/ac658b  

   Reefe, Michael A. ; Luque, Rafael ; Gaidos, Eric ; Beard, Corey ; Plavchan, Peter P. ; Cointepas, Marion ; Cale, Bryson L. ; Palle, Enric ; Parviainen, Hannu ; Feliz, Dax L. ; et al ( May 2022 , The Astronomical Journal)

   We present the validation of a transiting low-density exoplanet orbiting the M2.5 dwarf TOI 620 discovered by the NASA Transiting Exoplanet Survey Satellite (TESS) mission. We utilize photometric data from both TESS and ground-based follow-up observations to validate the ephemerides of the 5.09 day transiting signal and vet false-positive scenarios. High-contrast imaging data are used to resolve the stellar host and exclude stellar companions at separations ≳0.″2. We obtain follow-up spectroscopy and corresponding precise radial velocities (RVs) with multiple precision radial velocity (PRV) spectrographs to confirm the planetary nature of the transiting exoplanet. We calculate a 5σupper limit ofM_P< 7.1M_⊕andρ_P< 0.74 g cm⁻³, and we identify a nontransiting 17.7 day candidate. We also find evidence for a substellar (1–20M_J) companion with a projected separation ≲20 au from a combined analysis of Gaia, adaptive optics imaging, and RVs. With the discovery of this outer companion, we carry out a detailed exploration of the possibilities that TOI 620 b might instead be a circum-secondary planet or a pair of eclipsing binary stars orbiting the host in a hierarchical triple system. We find, under scrutiny, that we can exclude both of these scenarios from the multiwavelength transit photometry, thus validating TOI 620more »b as a low-density exoplanet transiting the central star in this system. The low density of TOI 620 b makes it one of the most amenable exoplanets for atmospheric characterization, such as with the James Webb Space Telescope and Ariel, validated or confirmed by the TESS mission to date.

   « less