We report results of a direct imaging survey for giant planets around 80 members of the β Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini NICI Planet-Finding Campaign. For this sample, we obtained median contrasts of ∆H=13.9 mag at 1" in combined CH 4 narrowband ADI+SDI 0 mode and median contrasts of ∆H=15.1 mag at 2" in H-band ADI mode. We found numerous (>70) candidate companions in our survey images. Some of these candidates were rejected as common-proper motion companions using archival data; we reobserved with NICI all other candidates that lay within 400 AU of the star and were not in dense stellar fields. The vast majority of candidate companions were confirmed as background objects from archival observations and/or dedicated NICI campaign followup. Four comoving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36±6 M Jup , 16.4±1.0 AU, Biller et al. 2010) , CD -35 2722B (31±8 M Jup , 67±4 AU, Wahhaj et al. 2011), HD 12894B (0.46±0.08 M ⊙ , 15.7±1.0 AU), and BD+07 1919C (0.20±0.03 M ⊙ , 12.5±1.4 AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law models of planet distributions and hot-start evolutionary models, we restrict the frequency of 1-20 M Jup companions at semi-major axes from 10-150 AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models. Our results strongly constrain the frequency of planets within semi-major axes of 50 AU as well. We restrict the frequency of 1-20 M Jup companions at semi-major axes from 10-50 AU to <21% at a 95.4% confidence level using DUSTY models and to <7% at a 95.4% using COND models. This survey is the deepest search to date for giant planets around young moving group stars.
We present a stellar mass-metallicity relation at z ∼ 1.4 with an unprecedentedly large sample of ∼ 340 star-forming galaxies obtained with FMOS on the Subaru Telescope. We observed K-band selected galaxies at 1.2 ≤ z ph ≤ 1.6 in the SXDS/UDS fields with M * ≥ 10 9.5 M ⊙ , and expected F(Hα) ≥ 5 × 10 −17 erg s −1 cm −2 . Among the observed ∼ 1200 targets, 343 objects show significant Hα emission lines. The gasphase metallicity is obtained from [N ii]λ6584/Hα line ratio, after excluding possible active galactic nuclei (AGNs). Due to the faintness of the [N ii]λ6584 lines, we apply the stacking analysis and derive the mass-metallicity relation at z ∼ 1.4. Our results are compared to past results at different redshifts in the literature. The mass-metallicity relation at z ∼ 1.4 is located between those at z ∼ 0.8 and z ∼ 2.2; it is found that the metallicity increases with decreasing redshift from z ∼ 3 to z ∼ 0 at fixed stellar mass. Thanks to the large size of the sample, we can study the dependence of the mass-metallicity relation on various galaxy physical properties. The average metallicity from the stacked spectra is close to the local FMR in the higher metallicity part but > ∼ 0.1 dex higher in metallicity than the FMR in the lower metallicity part. We find that galaxies with larger E(B − V ), B − R, and R − H colours tend to show higher metallicity by ∼ 0.05 dex at fixed stellar mass. We also find relatively clearer size dependence that objects with smaller half light radius tend to show higher metallicity by ∼ 0.1 dex at fixed stellar mass, especially in the low mass part.
We report the discovery of a tight substellar companion to the young solar analog PZ Tel, a member of the β Pic moving group observed with high contrast adaptive optics imaging as part of the Gemini NICI Planet-Finding Campaign. The companion Myr for the system, we estimate a mass of 36±6 M Jup based on the Lyon/DUSTY evolutionary models. PZ Tel B is one of few young substellar companions directly imaged at orbital separations similar to those of giant planets in our own solar system. Additionally, the primary star PZ Tel A shows a 70 µm emission excess, evidence for a significant quantity of circumstellar dust that has not been disrupted by the orbital motion of the companion.Subject headings: brown dwarfs -planetary systems -stars: pre-main sequence
We present the discovery of a wide (67 AU) substellar companion to the nearby (21 pc) young solar-metallicity M1 dwarf CD−35 2722, a member of the ≈100 Myr AB Doradus association. Two epochs of astrometry from the NICI Planet-Finding Campaign confirm that CD−35 2722 B is physically associated with the primary star. Near-IR spectra indicate a spectral type of L4±1 with a moderately low surface gravity, making it one of the coolest young companions found to date. The absorption lines and near-IR continuum shape of CD−35 2722 B agree especially well the dusty field L4.5 dwarf 2MASS J22244381−0158521, while the near-IR colors and absolute magnitudes match those of the 5-Myr old L4 planetary-mass companion, 1RXS J160929.1−210524 b. Overall, CD−35 2722 B appears to be an intermediate-age benchmark for L-dwarfs, with a less peaked H-band continuum than the youngest objects and near-IR absorption lines comparable to field -3objects. We fit Ames-Dusty model atmospheres to the near-IR spectra and find T ef f =1700-1900 K and log(g) =4.5±0.5. The spectra also show that the radial velocities of components A and B agree to within ±10 km/s, further confirming their physical association. Using the age and bolometric luminosity of CD−35 2722 B, we derive a mass of 31±8 M Jup from the Lyon/Dusty evolutionary models. Altogether, young late-M to mid-L type companions appear to be overluminous for their near-IR spectral type compared to field objects, in contrast to the underluminosity of young late-L and early-T dwarfs. 15M J 25M J 39M J 63M J 7M J 11M J 15M J 22M J 31M J 44M J 6M J 10M J 16M J 26M J 41M J 66M J
We present an extension of the spectral deconvolution (SD) method to achieve very high contrast at small inner working radii. We apply the method to the specific case of ground‐based adaptive optics fed integral field spectroscopy (without a coronagraph). Utilizing the wavelength dependence of the Airy and speckle patterns, we make an accurate estimate of the point spread function that can be scaled and subtracted from the data cube. The residual noise in the resulting spectra is very close to the photon noise from the starlight halo. We utilize the technique to extract a very high signal‐to‐noise ratio H‐ and K‐band spectrum of AB Doradus (AB Dor) C, the low‐mass companion to AB Dor A. By effectively eliminating all contamination from AB Dor A, the extracted spectrum retains both continuum and spectral features. The achieved 1σ contrast is 9 mag at 0.2 arcsec, 11 mag at 0.5 arcsec, in 20 min exposure time, at an effective spectral bandwidth of 5.5 nm, proving that the method is applicable even in low‐Strehl regimes. The SD method clearly demonstrates the efficacy of image slicer based integral field units in achieving very high contrast imaging spectroscopy at small angular separations, validating their use as high‐contrast spectrographs/imagers for extreme adaptive optics systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.