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

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⊙.

1998 ◽  
Vol 509 (2) ◽  
pp. L113-L116 ◽  
Author(s):  
E. L. Martín ◽  
G. Basri ◽  
W. Brandner ◽  
J. Bouvier ◽  
M. R. Zapatero Osorio ◽  
...  

2009 ◽  
Vol 5 (S267) ◽  
pp. 331-331
Author(s):  
J. A. Hernandez-Jimenez ◽  
H. Dottori ◽  
P. Grosbøl ◽  
N. Vera-Villamizar

We have studied Hubble Space Telescope archive imagery of the central region of the Seyfert 2 galaxy NGC 5427. The images were taken with F606W (V-band) and F160W (H-band) filters with the Wide Field and Planetary Camera 2 and the Near Infrared Camera and Multi-Object Spectrometer, respectively.


2009 ◽  
Vol 708 (2) ◽  
pp. 1241-1253 ◽  
Author(s):  
Maria Messineo ◽  
Donald F. Figer ◽  
Ben Davies ◽  
R. P. Kudritzki ◽  
R. Michael Rich ◽  
...  

2018 ◽  
Vol 610 ◽  
pp. A83 ◽  
Author(s):  
F. Nogueras-Lara ◽  
A. T. Gallego-Calvente ◽  
H. Dong ◽  
E. Gallego-Cano ◽  
J. H. V. Girard ◽  
...  

Context. The Galactic centre (GC) is of fundamental astrophysical interest, but existing near-infrared surveys fall short covering it adequately, either in terms of angular resolution, multi-wavelength coverage, or both. Here we introduce the GALACTICNUCLEUS survey, a JHKs imaging survey of the centre of the Milky Way with a 0.2″ angular resolution. Aims. The purpose of this paper is to present the observations of Field 1 of our survey, centred approximately on SgrA* with an approximate size of 7.95′ × 3.43′. We describe the observational set-up and data reduction pipeline and discuss the quality of the data. Finally, we present the analysis of the data. Methods. The data were acquired with the near-infrared camera High Acuity Wide field K-band Imager (HAWK-I) at the ESO Very Large Telescope (VLT). Short readout times in combination with the speckle holography algorithm allowed us to produce final images with a stable, Gaussian PSF (point spread function) of 0.2″ FWHM (full width at half maximum). Astrometric calibration is achieved via the VISTA Variables in the Via Lactea (VVV) survey and photometric calibration is based on the SIRIUS/Infrared Survey Facility telescope (IRSF) survey. The quality of the data is assessed by comparison between observations of the same field with different detectors of HAWK-I and at different times. Results. We reach 5σ detection limits of approximately J = 22, H = 21, and Ks = 20. The photometric uncertainties are less than 0.05 at J ≲ 20, H ≲ 17, and Ks ≲ 16. We can distinguish five stellar populations in the colour-magnitude diagrams; three of them appear to belong to foreground spiral arms, and the other two correspond to high- and low-extinction star groups at the GC. We use our data to analyse the near-infrared extinction curve and find some evidence for a possible difference between the extinction index between J − H and H − Ks. However, we conclude that it can be described very well by a power law with an index of αJHKs = 2.30 ± 0.08. We do not find any evidence that this index depends on the position along the line of sight, or on the absolute value of the extinction. We produce extinction maps that show the clumpiness of the ISM (interstellar medium) at the GC. Finally, we estimate that the majority of the stars have solar or super-solar metallicity by comparing our extinction-corrected colour-magnitude diagrams with isochrones with different metallicities and a synthetic stellar model with a constant star formation.


2009 ◽  
Vol 5 (H15) ◽  
pp. 545-545
Author(s):  
Issei Yamamura ◽  
Takashi Tsuji ◽  
Toshihiko Tanabé ◽  
Tadashi Nakajima

Brown dwarfs (hereafter BDs) are of particular interest because of their extremely low-temperature atmospheres for comparison with atmospheres of giant planets. Aiming to obtain clues to understand the formation and disappearance of dust clouds and molecular abundances in BD photospheres, we conducted an observation programme of space-borne near-infrared spectroscopy of bright BDs with the Infrared Camera (IRC) on-board AKARI.


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