Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSearching for young Jupiter analogs around AP Col: L-band high-contrast imaging of the closest pre-main sequence star
107
0
0.0
(
0
)
Authors
Sascha P. Quanz
Ask ChatGPT about the research
No Arabic abstract
The nearby M-dwarf AP Col was recently identified by Riedel et al. 2011 as a pre-main sequence star (age 12 - 50 Myr) situated only 8.4 pc from the Sun. The combination of its youth, distance, and intrinsically low luminosity make it an ideal target to search for extrasolar planets using direct imaging. We report deep adaptive optics observations of AP Col taken with VLT/NACO and Keck/NIRC2 in the L-band. Using aggressive speckle suppression and background subtraction techniques, we are able to rule out companions with mass m >= 0.5 - 1M_Jup for projected separations a>4.5 AU, and m >= 2 M_Jup for projected separations as small as 3 AU, assuming an age of 40 Myr using the COND theoretical evolutionary models. Using a different set of models the mass limits increase by a factor of ~2. The observations presented here are the deepest mass-sensitivity limits yet achieved within 20 AU on a star with direct imaging. While Doppler radial velocity surveys have shown that Jovian bodies with close-in orbits are rare around M-dwarfs, gravitational microlensing studies predict that ~17% of these stars host massive planets with orbital separations of 1-10 AU. Sensitive high-contrast imaging observations, like those presented here, will help to validate results from complementary detection techniques by determining the frequency of gas giant planets on wide orbits around M-dwarfs.
rate research
Read More
We report the detection of V1298 Tau b, a warm Jupiter-sized planet ($R_P$ = 0.91 $pm$ 0.05~ $R_mathrm{Jup}$, $P = 24.1$ days) transiting a young solar analog with an estimated age of 23 million years. The star and its planet belong to Group 29, a young association in the foreground of the Taurus-Auriga star-forming region. While hot Jupiters have been previously reported around young stars, those planets are non-transiting and near-term atmospheric characterization is not feasible. The V1298 Tau system is a compelling target for follow-up study through transmission spectroscopy and Doppler tomography owing to the transit depth (0.5%), host star brightness ($K_s$ = 8.1 mag), and rapid stellar rotation ($vsin{i}$ = 23 kms). Although the planet is Jupiter-sized, its mass is presently unknown due to high-amplitude radial velocity jitter. Nevertheless, V1298 Tau b may help constrain formation scenarios for at least one class of close-in exoplanets, providing a window into the nascent evolution of planetary interiors and atmospheres.
We present high-contrast observations of 68 young stellar objects (YSOs) explored as part of the SEEDS survey on the Subaru telescope. Our targets are very young ($<$10 Myr) stars, which often harbor protoplanetary disks where planets may be forming. We achieve a typical contrast of $sim$$10^{-4}$--$10^{-5.5}$ at an angular distance of 1arcsec from the central star, corresponding to typical mass sensitivities (assuming hot-start evolutionary models) of $sim$10 ${rm M_J}$ at 70 AU and $sim$6 ${rm M_J}$ at 140 AU. We detected a new stellar companion to HIP 79462 and confirmed the substellar objects GQ Lup b and ROXs 42B b. An additional six companion candidates await follow-up observations to check for common proper motion. Our SEEDS YSO observations probe the population of planets and brown dwarfs at the very youngest ages; these may be compared to the results of surveys targeting somewhat older stars. Our sample and the associated observational results will help enable detailed statistical analyses of giant planet formation.
AU Microscopii (AU Mic) is the second closest pre main sequence star, at a distance of 9.79 parsecs and with an age of 22 million years. AU Mic possesses a relatively rare and spatially resolved3 edge-on debris disk extending from about 35 to 210 astronomical units from the star, and with clumps exhibiting non-Keplerian motion. Detection of newly formed planets around such a star is challenged by the presence of spots, plage, flares and other manifestations of magnetic activity on the star. Here we report observations of a planet transiting AU Mic. The transiting planet, AU Mic b, has an orbital period of 8.46 days, an orbital distance of 0.07 astronomical units, a radius of 0.4 Jupiter radii, and a mass of less than 0.18 Jupiter masses at 3 sigma confidence. Our observations of a planet co-existing with a debris disk offer the opportunity to test the predictions of current models of planet formation and evolution.
We present observations of the nearby (D$sim$100,pc) Herbig star HD~163296 taken with the vortex coronograph at Keck/NIRC2 in the L band (3.7~$mu$m), to search for planetary mass companions in the ringed disc surrounding this pre-main sequence star. The images reveal an arc-like region of scattered light from the disc surface layers that is likely associated with the first bright ring detected with ALMA in the $lambda$=1.3mm dust continuum at $sim$65~au. We also detect a point-like source at $sim$0farcs5 projected separation in the North-East direction, close to the inner edge of the second gap in the millimetre images. Comparing the point source photometry with the atmospheric emission models of non-accreting giant planets, we obtain a mass of 6--7~M$_J$ for a putative protoplanet, assuming a system age of 5~Myr. Based on the contrast at a 95% level of completeness calculated on the emission-free regions of our images, we set upper limits for the masses of giant planets of 8--15~M$_J$, 4.5--6.5~M$_J$ and 2.5-4.0~M$_J$ at the locations of the first, second and third gap in the millimetre dust continuum, respectively. Further deep, high resolution thermal IR imaging of the HD~163296 system are warranted, to confirm the presence and nature of the point source and to better understand the structure of the dust disc.
MWC758 is a young star surrounded by a transitional disk. Recently, a protoplanet candidate has been detected around MWC758 through high-resolution $L$-band observations. The candidate is located inside the disk cavity at a separation of $sim$111 mas from the central star, and at an average position angle of $sim$165.5 degrees. We have performed simultaneous adaptive optics observations of MWC758 in the H$_{alpha}$ line and the adjacent continuum using SPHERE/ZIMPOL at the Very Large Telescope (VLT). We aim at detecting accreting protoplanet candidates through spectral angular differential imaging observations. The data analysis does not reveal any H$_{alpha}$ signal around the target. The derived contrast curve in the B_Ha filter allows us to derive a 5$sigma$ upper limit of $sim$7.6 mag at 111 mas, the separation of the previously detected planet candidate. This contrast translates into a H$_{alpha}$ line luminosity of $L_{rm H_{alpha}}lesssim$ 5$times$10$^{-5}$ $L_{odot}$ at 111 mas, and an accretion luminosity of $L_{acc} <$3.7$times$10$^{-4},L_{odot}$. For the predicted mass range of MWC758b, 0.5-5 $M_{rm Jup}$, this implies accretion rates of $dot M lesssim$ 3.4$times$(10$^{-8}$-10$^{-9}),M_{odot}/yr$, for an average planet radius of 1.1 $R_{rm Jup}$. Therefore, our estimates are consistent with the predictions of accreting circumplanetary accretion models for $R_{rm in} = 1 R_{rm Jup}$. In any case, the non-detection of any H$_{alpha}$ emitting source in the ZIMPOL images does not allow us to unveil the true nature of the $L$ detected source.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
