scholarly journals A search for a fifth planet around HR 8799 using the star-hopping RDI technique at VLT/SPHERE

2021 ◽  
Vol 648 ◽  
pp. A26 ◽  
Author(s):  
Z. Wahhaj ◽  
J. Milli ◽  
C. Romero ◽  
L. Cieza ◽  
A. Zurlo ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Mass Range ◽  
Giant Planets ◽  
Dual Band ◽  
High Signal ◽  
Reference Star ◽  
Resonant Orbits ◽  
Integral Field Spectroscopy ◽  
Dynamical Simulations ◽  
Difference Imaging

Context. Direct imaging of extrasolar giant planets demands the highest possible contrasts (ΔH ≳ 10 mag) at the smallest angular separations (∼0.1″) from the star. We present an adaptive optics observing method, called star-hopping, recently offered as standard queue observing (service mode) for the SPHERE instrument at the VLT. The method uses reference difference imaging (RDI) but, unlike earlier RDI applications, images of a reference star for PSF subtraction are obtained within minutes of observing the target star. Aims. We aim to significantly gain in contrast beyond the conventional angular differencing imaging (ADI) method to search for a fifth planet at separations less than 10 au, interior to the four giant planets of the HR 8799 system. The most likely semimajor axes allowed for this hypothetical planet, which were estimated via dynamical simulations in earlier works, were 7.5 au and 9.7 au within a mass range of 1–8 MJup. Methods. We obtained 4.5 h of simultaneous low-resolution integral field spectroscopy (R ∼ 30, Y − H band with IFS) and dual-band imaging (K1 and K2 bands with IRDIS) of the HR 8799 system, interspersed with observations of a reference star. The reference star was observed for about one-third of the total time and generally needs to be of similar brightness (ΔR ≲ 1 mag) and separated on sky by ≲1–2°. The hops between stars were made every 6–10 min, with only 1 min gaps in on-sky integration per hop. Results. We did not detect the hypothetical fifth planet at the most plausible separations, 7.5 and 9.7 au, down to mass limits of 3.6 MJup and 2.8 MJup, respectively, but attained an unprecedented contrast limit of 11.2 magnitudes at 0.1″. We detected all four planets with high signal-to-noise ratios. The YJH spectra for planets c, d were detected with redder H-band spectral slopes than found in earlier studies. As noted in previous works, the planet spectra are matched very closely by some red field dwarfs. Finally, comparing the current locations of the planets to orbital solutions, we found that planets e and c are most consistent with coplanar and resonant orbits. We also demonstrated that with star-hopping RDI, the contrast improvement at 0.1″ separation can be up to 2 mag. Conclusions. Since ADI, meridian transit and the concomitant sky rotation are not needed, the time of observation can be chosen from within a window that is two to three times larger. In general, star-hopping can be used for stars fainter than R = 4 magnitudes, since for these a reference star of suitable brightness and separation is usually available.

scholarly journals MOST Spacebased Photometry of HD 189733: Precise Timing Measurements for Transits Across an Active Star

2008 ◽  
Vol 4 (S253) ◽  
pp. 459-461
Author(s):  
E. Miller-Ricci ◽  
J. F. Rowe ◽  
D. Sasselov ◽  
J. M. Matthews ◽  
R. Kuschnig ◽  
...  
Keyword(s):  
Orbital Period ◽  
Mass Range ◽  
Active Star ◽  
Precise Timing ◽  
Resonant Orbits ◽  
The Earth ◽  
Test Spot ◽  
Transit Times ◽  
Nearly Continuous ◽  
Parent Star

AbstractWe have measured transit times for HD 189733 passing in front of its bright (V = 7.67) chromospherically active and spotted parent star. Nearly continuous broadband photometry of this system was obtained with the MOST (Microvariability & Oscillations of STars) space telesope during 21 days in August 2006, monitoring 10 consecutive transits. We have used these data to search for deviations from a constant orbital period which can indicate the presence of additional planets in the system that are as yet undetected by Doppler searches. We find no variations above the level of ±45 s, ruling out planets in the Earth-to-Neptune mass range in a number of resonant orbits. We find that a number of complications can arise in measuring transit times for a planet transiting an active star with large star spots. However, such transiting systems are also useful in that they can help to constrain and test spot models. This has implications for the large number of transiting systems expected to be discovered by the CoRoT and Kepler missions.

scholarly journals The SAMI Galaxy Survey: stellar population and structural trends across the Fundamental Plane

2021 ◽  
Author(s):  
Francesco D’Eugenio ◽  
Matthew Colless ◽  
Nicholas Scott ◽  
Arjen van der Wel ◽  
Roger L Davies ◽  
...  
Keyword(s):  
Stellar Population ◽  
Mass Density ◽  
Empirical Relation ◽  
Zero Point ◽  
High Signal ◽  
Fundamental Plane ◽  
Surface Mass ◽  
Integral Field Spectroscopy ◽  
Surface Mass Density ◽  
Photometric Measurements

Abstract We study the Fundamental Plane (FP) for a volume- and luminosity-limited sample of 560 early-type galaxies from the SAMI survey. Using r −band sizes and luminosities from new Multi-Gaussian Expansion (MGE) photometric measurements, and treating luminosity as the dependent variable, the FP has coefficients a = 1.294 ± 0.039, b = 0.912 ± 0.025, and zero-point c = 7.067 ± 0.078. We leverage the high signal-to-noise of SAMI integral field spectroscopy, to determine how structural and stellar-population observables affect the scatter about the FP. The FP residuals correlate most strongly (8σ significance) with luminosity-weighted simple-stellar-population (SSP) age. In contrast, the structural observables surface mass density, rotation-to-dispersion ratio, Sérsic index and projected shape all show little or no significant correlation. We connect the FP residuals to the empirical relation between age (or stellar mass-to-light ratio ϒ⋆ ) and surface mass density, the best predictor of SSP age amongst parameters based on FP observables. We show that the FP residuals (anti-)correlate with the residuals of the relation between surface density and ϒ⋆ . This correlation implies that part of the FP scatter is due to the broad age and ϒ⋆ distribution at any given surface mass density. Using virial mass and ϒ⋆ we construct a simulated FP and compare it to the observed FP. We find that, while the empirical relations between observed stellar population relations and FP observables are responsible for most (75 per cent) of the FP scatter, on their own they do not explain the observed tilt of the FP away from the virial plane.

scholarly journals High-contrast and resolution near-infrared photometry of the core of R136

2021 ◽  
Vol 503 (1) ◽  
pp. 292-311
Author(s):  
Zeinab Khorrami ◽  
Maud Langlois ◽  
Paul C Clark ◽  
Farrokh Vakili ◽  
Anne S M Buckner ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
Outer Region ◽  
Mass Range ◽  
Mass Function ◽  
Large Magellanic Cloud ◽  
Star Forming ◽  
The Core ◽  
Very Large Telescope ◽  
30 Doradus

ABSTRACT We present the sharpest and deepest near-infrared photometric analysis of the core of R136, a newly formed massive star cluster at the centre of the 30 Doradus star-forming region in the Large Magellanic Cloud. We used the extreme adaptive optics of the SPHERE focal instrument implemented on the ESO Very Large Telescope and operated in its IRDIS imaging mode for the second time with longer exposure time in the H and K filters. Our aim was to (i) increase the number of resolved sources in the core of R136, and (ii) to compare with the first epoch to classify the properties of the detected common sources between the two epochs. Within the field of view (FOV) of 10.8″ × 12.1″ ($2.7\,\text {pc}\times 3.0\, \text {pc}$), we detected 1499 sources in both H and K filters, for which 76 per cent of these sources have visual companions closer than 0.2″. The larger number of detected sources enabled us to better sample the mass function (MF). The MF slopes are estimated at ages of 1, 1.5, and 2 Myr, at different radii, and for different mass ranges. The MF slopes for the mass range of 10–300 M⊙ are about 0.3 dex steeper than the mass range of 3–300 M⊙, for the whole FOV and different radii. Comparing the JHK colours of 790 sources common in between the two epochs, 67 per cent of detected sources in the outer region (r > 3″) are not consistent with evolutionary models at 1–2 Myr and with extinctions similar to the average cluster value, suggesting an origin from ongoing star formation within 30 Doradus, unrelated to R136.

scholarly journals Investigating the young solar system analog HD 95086

2018 ◽  
Vol 617 ◽  
pp. A76 ◽  
Author(s):  
G. Chauvin ◽  
R. Gratton ◽  
M. Bonnefoy ◽  
A.-M. Lagrange ◽  
J. de Boer ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Scattered Light ◽  
Spectral Energy Distribution ◽  
Giant Planet ◽  
Giant Planets ◽  
Dual Band ◽  
Spectral Energy ◽  
Semi Major Axis ◽  
Integral Field Spectrograph

Context. HD 95086 (A8V, 17 Myr) hosts a rare planetary system for which a multi-belt debris disk and a giant planet of 4–5 MJup have been directly imaged. Aims. Our study aims to characterize the global architecture of this young system using the combination of radial velocity and direct imaging observations. We want to characterize the physical and orbital properties of HD 95086 b, search for additional planets at short and wide orbits and image the cold outer debris belt in scattered light. Methods. We used HARPS at the ESO 3.6 m telescope to monitor the radial velocity of HD 95086 over two years and investigate the existence of giant planets at less than 3 au orbital distance. With the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE at VLT, we imaged the faint circumstellar environment beyond 10 au at six epochs between 2015 and 2017. Results. We do not detect additional giant planets around HD 95086. We identify the nature (bound companion or background contaminant) of all point-like sources detected in the IRDIS field of view. None of them correspond to the ones recently discovered near the edge of the cold outer belt by ALMA. HD 95086 b is resolved for the first time in J-band with IFS. Its near-infrared spectral energy distribution is well fitted by a few dusty and/or young L7–L9 dwarf spectral templates. The extremely red 1–4 μm spectral distribution is typical of low-gravity objects at the L/T spectral type transition. The planet’s orbital motion is resolved between January 2015 and May 2017. Together with past NaCo measurements properly re-calibrated, our orbital fitting solutions favor a retrograde low to moderate-eccentricity orbit e = 0.2+0.3−0.2, with a semi-major axis ~52 au corresponding to orbital periods of ~288 yr and an inclination that peaks at i = 141°, which is compatible with a planet-disk coplanar configuration. Finally, we report the detection in polarimetric differential imaging of the cold outer debris belt between 100 and 300 au, consistent in radial extent with recent ALMA 1.3 mm resolved observations.

scholarly journals Kepler-411: a four-planet system with an active host star

2019 ◽  
Vol 624 ◽  
pp. A15 ◽  
Author(s):  
L. Sun ◽  
P. Ioannidis ◽  
S. Gu ◽  
J. H. M. M. Schmitt ◽  
X. Wang ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Detailed Characterization ◽  
Dynamical Interaction ◽  
Transiting Planets ◽  
Imaging Results ◽  
Adaptive Optics Imaging ◽  
Dynamical Simulations ◽  
Mutual Inclination ◽  
Rocky Planets

We present a detailed characterization of the Kepler-411 system (KOI 1781). This system was previously known to host two transiting planets: one with a period of 3 days (R = 2.4 R⊕; Kepler-411b) and one with a period of 7.8 days (R = 4.4 R⊕; Kepler-411c), as well as a transiting planetary candidate with a 58-day period (R = 3.3 R⊕; KOI 1781.03) from Kepler photometry. Here, we combine Kepler photometry data and new transit timing variation (TTV) measurements from all the Kepler quarters with previous adaptive-optics imaging results, and dynamical simulations, in order to constrain the properties of the Kepler-411 system. From our analysis, we obtain masses of 25.6 ± 2.6 M⊕ for Kepler-411b and 26.4 ± 5.9 M⊕ for Kepler-411c, and we confirm the planetary nature of KOI 1781.03 with a mass of 15.2 ± 5.1 M⊕, hence the name Kepler-411d. Furthermore, by assuming near-coplanarity of the system (mutual inclination below 30°), we discover a nontransiting planet, Kepler-411e, with a mass of 10.8 ± 1.1 M⊕ on a 31.5-day orbit, which has a strong dynamical interaction with Kepler-411d. With densities of 1.71 ± 0.39 g cm−3 and 2.32 ± 0.83 g cm−3, both Kepler-411c and Kepler-411d belong to the group of planets with a massive core and a significant fraction of volatiles. Although Kepler-411b has a sub-Neptune size, it belongs to the group of rocky planets.

The demographics of central massive black holes in low-mass early-type galaxies

2019 ◽  
Vol 14 (S353) ◽  
pp. 286-288
Author(s):  
Dieu D. Nguyen
Keyword(s):  
Black Holes ◽  
Adaptive Optics ◽  
Mass Range ◽  
Early Type ◽  
Host Galaxies ◽  
Seed Formation ◽  
Unique Constraint ◽  
Low Mass ◽  
Important Extension ◽  
Stellar Masses

AbstractThe existence intermediate mass black holes (IMBH, MBH ≲ 106M⊙) at the centers low-mass galaxies with stellar masses between (1–10)×10M⊙ are key to constraining the origin of black hole (BH) seeds and understanding the physics deriving the co-evolution of central BHs and their host galaxies. However, finding and weighing IMBH is challenging. Here, we present the first observational evidence for such IMBHs at the centers of the five nearest early-type galaxies (D < 3.5 Mpc, ETGs) revealed by adaptive optics kinematics from Gemini and VLT and high-resolution HST spectroscopy. We find that all five galaxies appear to host IMBHs with four of the five having masses below 1 million M⊙ and the lowest mass BH being only ∼7,000 M⊙. This work provides a first glimpse of the demographics of IMBHs in this galaxy mass range and at velocity dispersions < 70 km/s, and thus provides an important extension to the bulge mass and galaxy dispersion scaling relations. The ubiquity of central BHs in these galaxies provides a unique constraint on BH seed formation scenarios, favoring a formation mechanism that produces an abundance of low-mass seed BHs.

scholarly journals Kinematical signatures of disc instabilities and secular evolution in the MUSE TIMER Survey

2019 ◽  
Vol 14 (S353) ◽  
pp. 135-139
Author(s):  
Dimitri A. Gadotti ◽  
Adrian Bittner ◽  
Jesus Falcón-Barroso ◽  
Jairo Méndez-Abreu ◽  
Keyword(s):  
Spatial Resolution ◽  
High Signal ◽  
Stellar Kinematics ◽  
Secular Evolution ◽  
Integral Field Spectroscopy ◽  
Central Regions ◽  
Hydrodynamical Simulations ◽  
Cosmic History ◽  
Disc Galaxies ◽  
Integral Field

AbstractThe MUSE TIMER Survey has obtained high signal and high spatial resolution integral-field spectroscopy data of the inner ~ 6×6 kpc of 21 nearby massive disc galaxies. This allows studies of the stellar kinematics of the central regions of massive disc galaxies that are unprecedented in spatial resolution. We confirm previous predictions from numerical and hydrodynamical simulations of the effects of bars and inner bars on stellar and gaseous kinematics, and also identify box/peanuts via kinematical signatures in mildly and moderately inclined galaxies, including a box/peanut in a face-on inner bar. In 20/21 galaxies we find inner discs and show that their properties are fully consistent with the bar-driven secular evolution picture for their formation. In addition, we show that these inner discs have, in the region where they dominate, larger rotational support than the main galaxy disc, and discuss how their stellar population properties can be used to estimate when in cosmic history the main bar formed. Our results are compared with photometric studies in the context of the nature of galaxy bulges and we show that inner discs are identified in image decompositions as photometric bulges with exponential profiles (i.e., Sérsic indices near unity).

Theoretical predictions of mass, semimajor axis and eccentricity distributions of super-Earths

2010 ◽  
Vol 6 (S276) ◽  
pp. 64-71
Author(s):  
Shigeru Ida
Keyword(s):  
Semimajor Axis ◽  
Mass Range ◽  
Model Parameters ◽  
Type I ◽  
Orbital Eccentricity ◽  
Resonant Orbits ◽  
Theoretical Predictions ◽  
Giant Impacts ◽  
Solar Type ◽  
Host Stars

AbstractWe discuss the effects of close scattering and merging between planets on distributions of mass, semimajor axis and orbital eccentricity, using population synthesis model of planet formation, focusing on the distributions of close-in super-Earths, which are being observed recently. We found that a group of compact embryos emerge interior to the ice line, grow, migrate, and congregate into closely-packed convoys which stall in the proximity of their host stars. After the disk-gas depletion, they undergo orbit crossing, close scattering, and giant impacts to form multiple rocky Earths or super-Earths in non-resonant orbits around ~ 0.1AU with moderate eccentricities of ~ 0.01–0.1. The formation of these planets does not depend on model parameters such as type I migration speed. The fraction of solar-type stars with these super-Earths is anti-correlated with the fraction of stars with gas giants. The newly predicted family of close-in super-Earths makes less clear “planet desert” at intermediate mass range than our previous prediction.

scholarly journals Strategic Exploration of Exoplanets and Disks with Subaru: SEEDS

2010 ◽  
Vol 6 (S276) ◽  
pp. 436-437
Author(s):  
Nobuhiko Kusakabe ◽  
Motohide Tamura ◽  
Ryo Kandori ◽  
Tomoyuki Kudo ◽  
Jun Hashimoto ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Young Stars ◽  
Giant Planets ◽  
Current Status ◽  
High Contrast ◽  
Direct Imaging ◽  
Instrument Performance ◽  
Early Results ◽  
Solar Type ◽  
Adaptive Optics System

AbstractThe purpose of the SEEDS project (PI: M. Tamura) is to conduct a direct imaging survey, searching for giant planets as well as protoplanetary/debris disks at a few to a few tens of AU regions around 500 nearby solar-type or more massive young stars with the combination of the Subaru 8.2m telescope, the new high-contrast instrument HiCIAO, and the adaptive optics system AO188. After instrument performance verification, the SEEDS survey successfully started in October 2009. We have already detected many companion candidates to be followed-up, and clear and much better detections of disks or details of known disks structures. In this contribution, we will outline our goal, current status, early results, and future instrumentation plans.

scholarly journals Searching for Hα emitting sources around MWC 758

2018 ◽  
Vol 613 ◽  
pp. L5 ◽  
Author(s):  
N. Huélamo ◽  
G. Chauvin ◽  
H. M. Schmid ◽  
S. P. Quanz ◽  
E. Whelan ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Mass Range ◽  
Position Angle ◽  
Central Star ◽  
Young Star ◽  
Upper Limit ◽  
T Tauri ◽  
Very Large Telescope ◽  
Accretion Rates ◽  
Differential Imaging

Context. MWC 758 is a young star surrounded by a transitional disk. The disk shows an inner cavity and spiral arms that could be caused by the presence of protoplanets. Recently, a protoplanet candidate has been detected around MWC 758 through high-resolution L′-band observations. The candidate is located inside the disk cavity at a separation of ~111 mas from the central star, and at an average position angle of ~165.5°. Aims. We aim at detecting accreting protoplanet candidates within the disk of MWC 758 through angular spectral differential imaging (ASDI) observations in the optical regime. In particular, we explore the emission at the position of the detected planet candidate. Methods. We have performed simultaneous adaptive optics observations in the Hα line and the adjacent continuum using SPHERE/ZIMPOL at the Very Large Telescope (VLT). Results. The data analysis does not reveal any Hα signal around the target. The derived contrast curve in the B_Ha filter allows us to derive a 5σ upper limit of ~7.6 mag at 111 mas, the separation of the previously detected planet candidate. This contrast translates into a Hα line luminosity of LHα ≲ 5×10−5 L⊙ at 111 mas. Assuming that LHα scales with Lacc as in classical T Tauri stars (CTTSs) as a first approximation, we can estimate an accretion luminosity of Lacc < 3.7 × 10−4 L⊙ for the protoplanet candidate. For the predicted mass range of MWC 758b, 0.5–5 MJup, this implies accretion rates smaller than Ṁ < 3.4 × (10−8−10−9)M⊙ yr−1, for an average planet radius of 1.1 RJup. Therefore, our estimates are consistent with the predictions of accreting circumplanetary accretion models for Rin = 1RJup. The ZIMPOL line luminosity is consistent with the Hα upper limit predicted by these models for truncation radii ≲3.2 RJup. Conclusions. The non-detection of any Hα emitting source in the ZIMPOL images does not allow us to unveil the nature of the L′ detected source. Either it is a protoplanet candidate or a disk asymmetry.

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