Evidence of a Substellar Companion to AB Dor C

Climent, J. B.; Berger, J.‐P.; Guirado, J. C.; Marcaide, J. M.; Martí-Vidal, Iván; Mérand, A.; Tognelli, E.; Wittkowski, M.

doi:10.3847/2041-8213/ab5065

Cited by 11 publications

(10 citation statements)

References 44 publications

(76 reference statements)

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“…White et al (1988) had ruled out 8-GHz emission coming from component B but the system was later resolved at 5 GHz by Beasley & Cram (1993) and Lim (1993), with the latter work showing the highly polarized and variable nature of component B. The system has another component, C, which is a late-M dwarf with a substellar companion (Climent et al 2019) close to the main component but on the side of component B, so we cannot discard the possibility that some of the radio emission originates from it. The ASKAP emission is heavily blended, with a peak and integrated flux density of F 888, peak = 2.80 ± 0.05 mJy and F 888, total = 3.57 ± 0.07 mJy, respectively.…”

Section: Galactic Active Starsmentioning

confidence: 99%

The ASKAP-EMU Early Science Project: 888 MHz radio continuum survey of the Large Magellanic Cloud

Pennock

Loon

Filipović

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present an analysis of a new 120 deg2 radio continuum image of the Large Magellanic Cloud (LMC) at 888 MHz with a bandwidth of 288 MHz and beam size of $13\rlap{.}^{\prime \prime }9\times 12\rlap{.}^{\prime \prime }1$, from the Australian Square Kilometre Array Pathfinder (ASKAP) processed as part of the Evolutionary Map of the Universe (EMU) survey. The median Root Mean Squared noise is 58 μJy beam−1. We present a catalogue of 54,612 sources, divided over a Gold list (30,866 sources) complete down to 0.5 mJy uniformly across the field, a Silver list (22,080 sources) reaching down to < 0.2 mJy and a Bronze list (1,666 sources) of visually inspected sources in areas of high noise and/or near bright complex emission. We discuss detections of planetary nebulæ and their radio luminosity function, young stellar objects showing a correlation between radio luminosity and gas temperature, novæ and X-ray binaries in the LMC, and active stars in the Galactic foreground that may become a significant population below this flux level. We present examples of diffuse emission in the LMC (H ii regions, supernova remnants, bubbles) and distant galaxies showcasing spectacular interaction between jets and intracluster medium. Among 14,333 infrared counterparts of the predominantly background radio source population we find that star-forming galaxies become more prominent below 3 mJy compared to active galactic nuclei. We combine the new 888 MHz data with archival Australia Telescope Compact Array data at 1.4 GHz to determine spectral indices; the vast majority display synchrotron emission but flatter spectra occur too. We argue that the most extreme spectral index values are due to variability.

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Section: Galactic Active Starsmentioning

confidence: 99%

The ASKAP-EMU Early Science Project: 888 MHz radio continuum survey of the Large Magellanic Cloud

Pennock

Loon

Filipović

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…Pairs of brown dwarfs in wide orbits around stars have been discovered in several studies, such as Indi B (King et al 2010), GJ 569 B (Femenía et al 2011), GJ 417 B (Kirkpatrick et al 2001), HD 130948 B (Potter et al 2002) and AB Dor Ca/Cb (via interferometry, Climent et al 2019). This kind of configuration might extend to massive giant planets and brown dwarfs close to deuterium burning limits.…”

Section: Introductionmentioning

confidence: 93%

The search for disks or planetary objects around directly imaged companions: a candidate around DH Tauri B

Lazzoni

Zurlo

Desidera

et al. 2020

A&A

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Context. In recent decades, thousands of substellar companions have been discovered with both indirect and direct methods of detection. While the majority of the sample is populated by objects discovered using radial velocity and transit techniques, an increasing number have been directly imaged. These planets and brown dwarfs are extraordinary sources of information that help in rounding out our understanding of planetary systems. Aims. In this paper, we focus our attention on substellar companions detected with the latter technique, with the primary goal of investigating their close surroundings and looking for additional companions and satellites, as well as disks and rings. Any such discovery would shed light on many unresolved questions, particularly with regard to their possible formation mechanisms. Methods. To reveal bound features of directly imaged companions, whether for point-like or extended sources, we need to suppress the contribution from the source itself. Therefore, we developed a method based on the negative fake companion technique that first estimates the position in the field of view (FoV) and the flux of the imaged companion with high precision, then subtracts a rescaled model point spread function (PSF) from the imaged companion, using either an image of the central star or another PSF in the FoV. Next it performs techniques, such as angular differential imaging, to further remove quasi-static patterns of the star (i.e., speckle contaminants) that affect the residuals of close-in companions. Results. After testing our tools on simulated companions and disks and on systems that were chosen ad hoc, we applied the method to the sample of substellar objects observed with SPHERE during the SHINE GTO survey. Among the 27 planets and brown dwarfs we analyzed, most objects did not show remarkable features, which was as expected, with the possible exception of a point source close to DH Tau B. This candidate companion was detected in four different SPHERE observations, with an estimated mass of ~1MJup, and a mass ratio with respect to the brown dwarf of 1∕10. This binary system, if confirmed, would be the first of its kind, opening up interesting questions for the formation mechanism, evolution, and frequency of such pairs. In order to address the latter, the residuals and contrasts reached for 25 companions in the sample of substellar objects observed with SPHERE were derived. If the DH Tau Bb companion is real, the binary fraction obtained is ~7%, which is in good agreement with the results obtained for field brown dwarfs. Conclusions. While there may currently be many limitations affecting the exploration of bound features to directly imaged exoplanets and brown dwarfs, next-generation instruments from the ground and space (i.e., JWST, ELT, and LUVOIR) will be able to image fainter objects and, thus, drive the application of this technique in upcoming searches for exo-moons and circumplanetary disks.

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“…Close et al (2005) detected a significantly redder companion to AB Dor A, which they named AB Dor C , at 0.156 ± 0.010 and position angle 127 ± 1 • , with a dynamical mass of 0.090 ± 0.008 M (Azulay et al 2017). Climent et al (2019) inferred the presence of a companion to AB Dor C in VLTI/AMBER J,H,K band, with 38 ± 1 mas separation and masses of 0.072 ± 0.013 and 0.013 ± 0.01 M for AB Dor Ca, Cb respectively. Close et al (2005) Rodigas et al (2015) used this system as a test case in their BDI paper.…”

Section: Appendix a Binary System Detailsmentioning

confidence: 99%

Companion mass limits for 17 binary systems obtained with binary differential imaging and MagAO/Clio

Pearce

Males

Weinberger

et al. 2022

Monthly Notices of the Royal Astronomical Society

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Improving direct detection capability close to the star through improved star-subtraction and post-processing techniques is vital for discovering new low-mass companions and characterizing known ones at longer wavelengths. We present results of 17 binary star systems observed with the Magellan Adaptive Optics system (MagAO) and the Clio infrared camera on the Magellan Clay Telescope using Binary Differential Imaging (BDI). BDI is an application of Reference Differential Imaging (RDI) and Angular Differential Imaging (ADI) applied to wide binary star systems (2″ <Δρ < 10″) within the isoplanatic patch in the infrared. Each star serves as the point-spread-function (PSF) reference for the other, and we performed PSF estimation and subtraction using Principal Component Analysis. We report contrast and mass limits for the 35 stars in our initial survey using BDI with MagAO/Clio in L′ and 3.95μm bands. Our achieved contrasts varied between systems, and spanned a range of contrasts from 3.0-7.5 magnitudes and a range of separations from 0.2″to ∼2″. Stars in our survey span a range of masses, and our achieved contrasts correspond to late-type M dwarf masses down to ∼10 MJup. We also report detection of a candidate companion signal at 0.2″(18 AU) around HIP 67506 A (SpT G5V, mass ∼1.2 M⊙), which we estimate to be $\sim 60-90~\mbox{M$_{\rm Jup}$}$. We found that the effectiveness of BDI is highest for approximately equal brightness binaries in high-Strehl conditions.

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Evidence of a Substellar Companion to AB Dor C

Cited by 11 publications

References 44 publications

The ASKAP-EMU Early Science Project: 888 MHz radio continuum survey of the Large Magellanic Cloud

The ASKAP-EMU Early Science Project: 888 MHz radio continuum survey of the Large Magellanic Cloud

The search for disks or planetary objects around directly imaged companions: a candidate around DH Tauri B

Companion mass limits for 17 binary systems obtained with binary differential imaging and MagAO/Clio

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