scholarly journals The extreme colliding-wind system Apep: resolved imagery of the central binary and dust plume in the infrared

2020 ◽  
Vol 498 (4) ◽  
pp. 5604-5619
Author(s):  
Y Han ◽  
P G Tuthill ◽  
R M Lau ◽  
A Soulain ◽  
J R Callingham ◽  
...  
Keyword(s):  
Proper Motion ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Geometric Model ◽  
Close Binary ◽  
High Angular Resolution ◽  
Wind System ◽  
Orbital Parameters ◽  
Motion Study ◽  
Triple Star

ABSTRACT The recent discovery of a spectacular dust plume in the system 2XMM J160050.7–514245 (referred to as ‘Apep’) suggested a physical origin in a colliding-wind binary by way of the ‘Pinwheel’ mechanism. Observational data pointed to a hierarchical triple-star system, however, several extreme and unexpected physical properties seem to defy the established physics of such objects. Most notably, a stark discrepancy was found in the observed outflow speed of the gas as measured spectroscopically in the line-of-sight direction compared to the proper motion expansion of the dust in the sky plane. This enigmatic behaviour arises at the wind base within the central Wolf–Rayet binary: a system that has so far remained spatially unresolved. Here, we present an updated proper motion study deriving the expansion speed of Apep’s dust plume over a 2-year baseline that is four times slower than the spectroscopic wind speed, confirming and strengthening the previous finding. We also present the results from high angular resolution near-infrared imaging studies of the heart of the system, revealing a close binary with properties matching a Wolf–Rayet colliding-wind system. Based on these new observational constraints, an improved geometric model is presented yielding a close match to the data, constraining the orbital parameters of the Wolf–Rayet binary and lending further support to the anisotropic wind model.

scholarly journals Investigating close binary supermassive black holes at high angular resolution

2021 ◽  
pp. 1-16
Author(s):  
A. Kovacevic
Keyword(s):  
Black Holes ◽  
Supermassive Black Holes ◽  
High Mass ◽  
Close Binary ◽  
Close Binaries ◽  
High Angular Resolution ◽  
Mutual Distance ◽  
Galaxy Mergers ◽  
Orbital Parameters ◽  
Reverberation Mapping

Gravitational waves (GW) in the nano-Hz domain are expected to be radiated by close-binaries of supermassive black holes (CB-SMBHs; components bound in a Keplerian binary at mutual distance less than ~ 0.1 pc), which are relicts of galaxy mergers and anticipated to be measured via the Pulsar Timing Array (PTA) technique. The challenge of present CB-SMBH investigations is that their signatures are elusive and not easily disentangled from a single SMBH. PTAs will typically have a glimpse of an early portion of the binary inspiral to catch the frequency evolution of the binary only with sufficiently high mass and initially high eccentricity. Thus, we have to make use of electromagnetic observations to determine orbital parameters of CB-SMBHs and test nano-Hz GW properties. The 2D reverberation mapping (RM) is a powerful tool for probing kinematics and geometry of ionized gas in the SMBHs (single or binary) vicinity, yet it can lose information due to projection on the line of sight of the observer. Nevertheless, spectroastrometry with AMBER, GRAVITY, and successors can provide an independent measurement of the emitting region's size, geometry, and kinematics. These two techniques combined can resolve CB-SMBHs. In this review, we focus on RM and spectroastrometry observational signatures of CB-SMBHs with non-zero eccentricity from recent simulations with particular attention to recent developments and open issues.

scholarly journals A low-mass triple system with a wide L/T transition brown dwarf component: NLTT 51469AB/SDSS 2131−0119

2019 ◽  
Vol 487 (1) ◽  
pp. 1149-1159 ◽  
Author(s):  
B Gauza ◽  
V J S Béjar ◽  
A Pérez-Garrido ◽  
N Lodieu ◽  
R Rebolo ◽  
...  
Keyword(s):  
Spectral Type ◽  
Proper Motion ◽  
Near Infrared ◽  
Close Binary ◽  
Mass Star ◽  
X Rays ◽  
Brown Dwarf ◽  
Uv Excess ◽  
Low Mass ◽  
Gaia Dr2

Abstract We demonstrate that the previously identified L/T transition brown dwarf SDSS J213154.43−011939.3 (SDSS 2131−0119) is a widely separated (82${^{\prime\prime}_{.}}$3, ∼3830 au) common proper motion companion to the low-mass star NLTT 51469, which we reveal to be a close binary itself, separated by 0${^{\prime\prime}_{.}}$64 ± 0${^{\prime\prime}_{.}}$01 (∼30 au). We find the proper motion of SDSS 2131−0119 of μαcos δ = −100 ± 20 mas yr−1 and μδ = −230 ± 20 mas yr−1 consistent with the proper motion of the primary provided by Gaia DR2: μαcos δ = −95.49 ± 0.96 mas yr−1 and μδ = −239.38 ± 0.96 mas yr−1. Based on optical and near-infrared spectroscopy, we classify the primary NLTT 51469A as an M3 ± 1 dwarf, estimate photometrically the spectral type of its close companion NLTT 51469B at ∼M6, and confirm the spectral type of the brown dwarf to be L9 ± 1. Using radial velocity, proper motion, and parallax, we derived the UVW Galactic space velocities of NLTT 51469A, showing that the system does not belong to any known young stellar moving group. The high V, W velocities, lack of a 670.8 nm Li i absorption line, and absence of H α emission, detected X-rays, or UV excess, indicate that the system is likely a member of the thin disc population and is older than 1 Gyr. For the parallactic distance of 46.6 ± 1.6 pc from Gaia DR2, we determined luminosities of $-1.50^{+0.02}_{-0.04}$ and −4.4 ± 0.1 dex of the M3 and L9, respectively. Considering the spectrophotometric estimation, which yields a slightly lower distance of $34^{+10}_{-13}$ pc, the obtained luminosities are $-1.78^{+0.02}_{-0.04}$ and $-4.7^{+0.3}_{-0.5}$ dex. We also estimated their effective temperatures and masses, and obtained 3410$^{+140}_{-210}$ K and 0.42 ± 0.02 M⊙ for the primary, and 1400–1650 K and 0.05–0.07 M⊙ for the wide companion. For the ∼M6 component, we estimated Teff = 2850 ± 200 K and m = 0.10$^{+0.06}_{-0.01}$ M⊙.

scholarly journals Search for giant planets around seven white dwarfs in the Hyades cluster with the Hubble Space Telescope

2020 ◽  
Vol 500 (3) ◽  
pp. 3920-3925
Author(s):  
Wolfgang Brandner ◽  
Hans Zinnecker ◽  
Taisiya Kopytova
Keyword(s):  
White Dwarfs ◽  
Near Infrared ◽  
Hubble Space Telescope ◽  
Infrared Camera ◽  
Detection Limits ◽  
Giant Planets ◽  
High Angular Resolution ◽  
Mass Detection ◽  
Space Telescope ◽  
Hyades Cluster

ABSTRACT Only a small number of exoplanets have been identified in stellar cluster environments. We initiated a high angular resolution direct imaging search using the Hubble Space Telescope (HST) and its Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument for self-luminous giant planets in orbit around seven white dwarfs in the 625 Myr old nearby (≈45 pc) Hyades cluster. The observations were obtained with Near-Infrared Camera 1 (NIC1) in the F110W and F160W filters, and encompass two HST roll angles to facilitate angular differential imaging. The difference images were searched for companion candidates, and radially averaged contrast curves were computed. Though we achieve the lowest mass detection limits yet for angular separations ≥0.5 arcsec, no planetary mass companion to any of the seven white dwarfs, whose initial main-sequence masses were >2.8 M⊙, was found. Comparison with evolutionary models yields detection limits of ≈5–7 Jupiter masses (MJup) according to one model, and between 9 and ≈12 MJup according to another model, at physical separations corresponding to initial semimajor axis of ≥5–8 au (i.e. before the mass-loss events associated with the red and asymptotic giant branch phase of the host star). The study provides further evidence that initially dense cluster environments, which included O- and B-type stars, might not be highly conducive to the formation of massive circumstellar discs, and their transformation into giant planets (with m ≥ 6 MJup and a ≥6 au). This is in agreement with radial velocity surveys for exoplanets around G- and K-type giants, which did not find any planets around stars more massive than ≈3 M⊙.

Near-Infrared Imaging Photoplethysmography During Driving

2020 ◽  
pp. 1-12
Author(s):  
Ewa M. Nowara ◽  
Tim K. Marks ◽  
Hassan Mansour ◽  
Ashok Veeraraghavan
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Near Infrared Imaging
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