15 research outputs found
The companion candidate near Fomalhaut - a background neutron star?
Stars and planetary systemsHigh Energy Astrophysic
A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS:First polarimetric detections revealing disks around DH Tau B and GSC 6214-210 B
Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS):A close low-mass companion to ET Cha
An extended scattered light disk around AT Pyx: possible planet formation in a cometary globule
Stars and planetary system
First spectroscopic observations of the substellar companion of the young debris disk star PZ Telescopii
Context. In 2010 a substellar companion to the solar analog pre-main sequence star PZ Tel and member of the approximately 12 Myr old beta Pic moving group was found by high-contrast direct imaging independently by two teams. Aims. In order to determine the basic parameters of this companion more precisely and independent of evolutionary models, hence age-independent, we obtained follow-up spectroscopic observations of the primary and companion. Methods. We used the Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) at the Very Large Telescope Unit 4/Yepun of ESO's Paranal Observatory in the H + K band and processed the data using the spectral deconvolution technique. The resulting spectrum of the companion was then compared to a grid of DRIFT-PHOENIX synthetic model spectra, a combination of a general-purpose model atmosphere code with a non-equilibrium, stationary cloud and dust model, using a chi(2) minimization analysis. Results. We find a best fitting spectral type of G6.5 for PZ Tel A. The extracted spectrum of the substellar companion, at a spatial position compatible with earlier orbit estimates, yields a temperature T-eff = 2500(-115)(+138) K, a visual extinction A(V) = 0.53(-0.53)(+0.84) mag, a surface gravity of log g = 3.50(-0.30)(+0.51) dex, and a metallicity at the edge of the grid of [M/H] = 0.30(-0.30) dex. Conclusions. We derive a luminosity of log(L-bol/L-circle dot) = -2.66(-0.08)(+0.06), a radius of R = 2.42(-0.34)(+0.28) R-Jup, and a mass of M = 7.5(-4.3)(+16.9) M-Jup for the PZ Tel companion, which is consistent with most earlier estimates using photometry alone. Combining our results with evolutionary models, we find a best-fitting mass of about 21 Jupiter masses at an age corresponding to the recently determined lithium depletion age of 7(-2)(+4) Myr. Hence, the PZ Tel companion is most likely a wide brown dwarf companion in the 12(-4)(+8) Myr old beta Pic moving group
Observations of the transiting planet TrES-2 with the AIU Jena telescope in GroĂschwabhausen
We have started high precision photometric monitoring observations at the AIU
Jena observatory in Grossschwabhausen near Jena in fall 2006. We used a 25 cm
Cassegrain telescope equipped with a CCD-camera mounted picky-pack on a 90 cm
telescope. To test the obtainable photometric precision, we observed stars with
known transiting planets. We could recover all planetary transits observed by
us. We observed the parent star of the transiting planet TrES-2 over a longer
period in Grossschwabhausen. Between March and November 2007 seven different
transits and almost a complete orbital period were analyzed. Overall, in 31
nights of observation 3423 exposures (in total 57.05 h of observation) of the
TrES-2 parent star were taken. Here, we present our methods and the resulting
light curves. Using our observations we could improve the orbital parameters of
the system.Comment: 4 pages, 2 figures, conference proceeding
Observations of planetary transits at the University Observatory Jena
We report on observations of transit events of the transiting planets XO-1b, TrES-1 and TrES-2 with a 25 cm telescope of the University Observatory Jena. With the help of all available transit times from literature including our own photometry our measurements allowed us to refine the estimate of the orbital period of all three transiting planets observed by us