arXiv subjects

Zs. Regaly

Publications and source records attributed to Zs. Regaly.

21 records · Page 2Linked to original sources

arXiv2010

High-resolution spectroscopic view of planet formation sites

Theories of planet formation predict the birth of giant planets in the inner, dense, and gas-rich regions of the circumstellar disks around young stars. These are the regions from which strong CO emission is expected. Observations have so far been unable to confirm the presence of planets caught in formation. We have developed a novel method to detect a giant planet still embedded in a circumstellar disk by the distortions of the CO molecular line profiles emerging from the protoplanetary disk's surface. The method is based on the fact that a giant planet significantly perturbs the gas velocity flow in addition to distorting the disk surface density. We have calculated the emerging molecular line profiles by combining hydrodynamical models with semianalytic radiative transfer calculations. Our results have shown that a giant Jupiter-like planet can be detected using contemporary or future high-resolution near-IR spectrographs such as VLT/CRIRES or ELT/METIS. We have also studied the effects of binarity on disk perturbations. The most interesting results have been found for eccentric circumprimary disks in mid-separation binaries, for which the disk eccentricity - detectable from the asymmetric line profiles - arises from the gravitational effects of the companion star. Our detailed simulations shed new light on how to constrain the disk kinematical state as well as its eccentricity profile. Recent findings by independent groups have shown that core-accretion is severely affected by disk eccentricity, hence detection of an eccentric protoplanetary disk in a young binary system would further constrain planet formation theories.

astro-ph.SR↗

arXiv2010

Detectability of giant planets in protoplanetary disks by CO emission lines

In this paper we intend to provide an indirect method to detect Jovian planets by studying near infrared emission spectra originating in the protoplanetary disks around T Tauri stars. Our idea is to investigate whether a massive planet could induce any observable effect on the spectral lines emerging in the disks atmosphere. As a tracer molecule we propose CO, which is excited in the ro-vibrational fundamental band in the disk atmosphere to a distance of ~2-3 AU (depending on the stellar mass) where terrestrial planets are thought to form. The synthetic molecular spectral line profiles were calculated by an own developed semi-analytical double layer disk model. 2D gas dynamics were incorporated in the calculation of synthetic spectral lines. We demonstrate that a massive planet embedded in a protoplanetary disk strongly influences the originally circular Keplerian gas dynamics. The perturbed motion of the gas can be detected by comparing the CO line profiles in emission, which is emerge from planet-bearing to those of planet-free disk models. The planet signal has two major characteristics: a permanent line profile asymmetry, and short timescale variability correlated with the orbital phase of the giant planet. We have found that the strength of the asymmetry depends on the physical parameters of the star-planet-disk system, such as the disk inclination angle, the planetary and stellar masses, the orbital distance, and the size of the disk inner cavity. The permanent line profile asymmetry is caused by a disk in an eccentric state in the gap opened by the giant planet. However, the variable component is a consequence of the local dynamical perturbation by the orbiting giant planet. We show that a forming giant planet, still embedded in the protoplanetary disk, can be detected using contemporary or future high-resolution near-IR spectrographs like VLT/CRIRES and ELT/METIS.

astro-ph.SR↗

arXiv2006

A possible interrelation between the estimated luminosity distances and internal extinctions of type Ia supernovae

We studied the statistical properties of the luminosity distance and internal extinction data of type Ia supernovae in the lists published by Tonry et al. (2003) and Barris et al. (2004). After selecting the luminosity distance in an empty Universe as a reference level we divided the sample into low $z<0.25$ and high $z \ge 0.25$ parts. We further divided these subsamples by the median of the internal extinction. Performing sign tests using the standardized residuals between the estimated logarithmic luminosity distances and those of an empty universe, on the four subsamples separately, we recognized that the residuals were distributed symmetrically in the low redshift region, independently from the internal extinction. On the contrary, the low extinction part of the data of $z \ge 0.25$ clearly showed an excess of the points with respect to an empty Universe which was not the case in the high extinction region. This diversity pointed to an interrelation between the estimated luminosity distance and internal extinction. To characterize quantitatively this interrelation we introduced a hidden variable making use of the technics of factor analysis. After subtracting that part of the residual which was explained by the hiddenmaking use of the technics of factor analysis. After subtracting that part of the residual which was explained by the hidden variable we obtained luminosity distances which were already free from interrelation with internal extinction. Fitting the corrected luminosity distances with cosmological models we concluded that the SN Ia data alone did not exclude the possibility of the $Λ=0$ solution.

astro-ph↗