- ID:
- ivo://CDS.VizieR/J/ApJ/715/1050
- Title:
- Predicted abundances for extrasolar planets. I.
- Short Name:
- J/ApJ/715/1050
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extrasolar planet host stars have been found to be enriched in key planet-building elements. These enrichments have the potential to drastically alter the composition of material available for terrestrial planet formation. Here, we report on the combination of dynamical models of late-stage terrestrial planet formation within known extrasolar planetary systems with chemical equilibrium models of the composition of solid material within the disk. This allows us to determine the bulk elemental composition of simulated extrasolar terrestrial planets. A wide variety of resulting planetary compositions are found, ranging from those that are essentially "Earth like", containing metallic Fe and Mg silicates, to those that are dominated by graphite and SiC. This shows that a diverse range of terrestrial planets may exist within extrasolar planetary systems.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/765/9
- Title:
- Predicted CO and [CII] fluxes of HUDF galaxies
- Short Name:
- J/ApJ/765/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Modern (sub-)millimeter/radio interferometers such as ALMA, JVLA, and the PdBI successor NOEMA will enable us to measure the dust and molecular gas emission from galaxies that have luminosities lower than the Milky Way, out to high redshifts and with unprecedented spatial resolution and sensitivity. This will provide new constraints on the star formation properties and gas reservoir in galaxies throughout cosmic times through dedicated deep field campaigns targeting the CO/[C II] lines and dust continuum emission in the (sub-)millimeter regime. In this paper, we present empirical predictions for such line and continuum deep fields. We base these predictions on the deepest available optical/near-infrared Advanced Camera for Surveys and NICMOS data on the Hubble Ultra Deep Field (over an area of about 12arcmin^2^). Using a physically motivated spectral energy distribution model, we fit the observed optical/near-infrared emission of 13099 galaxies with redshifts up to z=5, and obtain median-likelihood estimates of their stellar mass, star formation rate, dust attenuation, and dust luminosity. We combine the attenuated stellar spectra with a library of infrared emission models spanning a wide range of dust temperatures to derive statistical constraints on the dust emission in the infrared and (sub-)millimeter which are consistent with the observed optical/near-infrared emission in terms of energy balance. This allows us to estimate, for each galaxy, the (sub-)millimeter continuum flux densities in several ALMA, PdBI/NOEMA, and JVLA bands. As a consistency check, we verify that the 850{mu}m number counts and extragalactic background light derived using our predictions are consistent with previous observations. Using empirical relations between the observed CO/[C II] line luminosities and the infrared luminosity of star-forming galaxies, we infer the luminosity of the CO(1-0) and [C II] lines from the estimated infrared luminosity of each galaxy in our sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/179/451
- Title:
- Predicted IR excesses for protoplanetary disks
- Short Name:
- J/ApJS/179/451
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe calculations for the formation of icy planets and debris disks at 30-150AU around 1-3M_{sun}_ stars. Debris disk formation coincides with the formation of planetary systems. As protoplanets grow, they stir leftover planetesimals to large velocities. A cascade of collisions then grinds the leftovers to dust, forming an observable debris disk. Stellar lifetimes and the collisional cascade limit the growth of protoplanets. The maximum radius of icy planets, r_max_~1750km, is remarkably independent of initial disk mass, stellar mass, and stellar age. These objects contain <=3%-4% of the initial mass in solid material. Collisional cascades produce debris disks with maximum luminosity ~2x10^-3^ times the stellar luminosity. The peak 24um excess varies from ~1% times the stellar photospheric flux for 1M_{sun}_ stars to ~50 times the stellar photospheric flux for 3M_{sun}_ stars. The peak 70-850um excesses are ~30-100 times the stellar photospheric flux. For all stars, the 24-160um excesses rise at stellar ages of 5-20Myr, peak at 10-50Myr, and then decline. The decline is roughly a power law, f{propto}t^-n^ with n~0.6-1.0. This predicted evolution agrees with published observations of A-type and solar-type stars. The observed far-IR color evolution of A-type stars also matches model predictions.
- ID:
- ivo://CDS.VizieR/J/A+A/651/A55
- Title:
- Predicted redshifts of galaxies with NetZ
- Short Name:
- J/A+A/651/A55
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The redshifts of galaxies are a key attribute that is needed for nearly all extragalactic studies. Since spectroscopic redshifts require additional telescope and human resources, millions of galaxies are known without spectroscopic redshifts. Therefore, it is crucial to have methods for estimating the redshift of a galaxy based on its photometric properties, the so-called photo-z. We developed NetZ, a new method using a Convolutional Neural Network (CNN) to predict the photo-z based on galaxy images, in contrast to previous methods which often used only the integrated photometries of galaxies without their images. We use data from the Hyper Suprime-Cam Subaru Strategic Program (HSC SSP) in five different filters as training data. The network over the whole redshift range between 0 and 4 performs well overall and especially in the high-z range better than other methods on the same data. We obtain an accuracy |zpred-zref| of sigma=0.12 (68% confidence interval) with a CNN working for all galaxy types averaged over all galaxies in the redshift range of 0 to ~4. By limiting to smaller redshift ranges or to Luminous Red Galaxies (LRGs), we find a further notable improvement. We publish more than 34 million new photo-z values predicted with NetZ here. This shows that the new method is very simple and fast to apply, and, importantly, covers a wide redshift range limited only by the available training data. It is broadly applicable and beneficial to imaging surveys, particularly upcoming surveys like the Rubin Observatory Legacy Survey of Space and Time which will provide images of billions of galaxies with similar image quality as HSC.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/49
- Title:
- Predictions of giant exoplanet host star's
- Short Name:
- J/ApJ/880/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The presence of certain elements within a star, and by extension its planet, strongly impacts the formation and evolution of the planetary system. The positive correlation between a host star's iron content and the presence of an orbiting giant exoplanet has been confirmed; however, the importance of other elements in predicting giant planet occurrence is less certain despite their central role in shaping internal planetary structure. We designed and applied a machine-learning algorithm to the Hypatia Catalog to analyze the stellar abundance patterns of known host stars to determine those elements important in identifying potential giant exoplanet host stars. We analyzed a variety of different elements ensembles-namely, volatiles, lithophiles, siderophiles, and Fe. We show that the relative abundances of oxygen, carbon, and sodium, in addition to iron, are influential indicators of the presence of a giant planet. We demonstrate the predictive power of our algorithm by analyzing stars with known giant planets and found that they had median 75% prediction score. We present a list of ~350 stars with no currently discovered planets that have a >=90% prediction probability likelihood of hosting a giant exoplanet. We investigated archival HARPS data and found significant trends that HIP 62345, HIP 71803, and HIP 10278 host long-period giant planet companions with estimated minimum M_p_sin(i) values of 3.7, 6.8, and 8.5M_J_, respectively. We anticipate that our findings will revolutionize future target selection, the role that elements play in giant planet formation, and the determination of giant planet interior structure models.
- ID:
- ivo://CDS.VizieR/J/A+A/510/A46
- Title:
- Pre-main sequence evolutionary tracks
- Short Name:
- J/A+A/510/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Magnetic fields are at the heart of the observed stellar activity in late-type stars, and they are presumably generated by a dynamo mechanism at the interface layer (tachocline) between the radiative core and the base of the convective envelope. Since dynamo models are based on the interaction between differential rotation and convective motions, the introduction of rotation in the ATON 2.3 stellar evolutionary code allows for explorations regarding a physically consistent treatment of magnetic effects in stellar structure and evolution, even though there are formidable mathematical and numerical challenges involved.
- ID:
- ivo://CDS.VizieR/J/A+A/494/209
- Title:
- Pre-main sequence evolutionary tracks
- Short Name:
- J/A+A/494/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In close binary systems, the axial rotation and the mutual tidal forces of the component stars deform each other and destroy their spherical symmetry by means of the respective disturbing potentials. We present new models for low-mass, pre-main sequence stars that include the combined distortion effects of tidal and rotational forces on the equilibrium configuration of stars. Using our theoretical results, we aim at investigating the effects of interaction between tides and rotation on the stellar structure and evolution.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A49
- Title:
- Pre-main sequence stars evolutionary models
- Short Name:
- J/A+A/599/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Protostars grow from the first formation of a small seed and subsequent accretion of material. Recent theoretical work has shown that the pre-main-sequence (PMS) evolution of stars is much more complex than previously envisioned. Instead of the traditional steady, one-dimensional solution, accretion may be episodic and not necessarily symmetrical, thereby affecting the energy deposited inside the star and its interior structure. Given this new framework, we want to understand what controls the evolution of accreting stars. We use the MESA stellar evolution code with various sets of conditions. In particular, we account for the (unknown) efficiency of accretion in burying gravitational energy into the protostar through a parameter, ksi, and we vary the amount of deuterium present. We confirm the findings of previous works that, in terms of evolutionary tracks on an Hertzprung-Russell (H-R) diagram, the evolution changes significantly with the amount of energy that is lost during accretion. We find that deuterium burning also regulates the PMS evolution. In the low-entropy accretion scenario, the evolutionary tracks in the H-R diagram are significantly different from the classical tracks and are sensitive to the deuterium content. A comparison of theoretical evolutionary tracks and observations allows us to exclude some cold accretion models (ksi~0) with low deuterium abundances.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A132
- Title:
- Pre-main sequence stars evolutionary models. II
- Short Name:
- J/A+A/618/A132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We want to investigate how planet formation is imprinted on stellar surface composition using up-to-date stellar evolution models. We simulate the evolution of pre-main-sequence stars as a function of the efficiency of heat injection during accretion, the deuterium mass fraction, and the stellar mass, M*. For simplicity, we assume that planet formation leads to the late accretion of zero-metallicity gas, diluting the surface stellar composition as a function of the mass of the stellar outer convective zone. We estimate that in the solar system, between 97 and 168 Mearth of condensates formed planets or were ejected from the system. We adopt 150 M_earth_(M*/M_sun_)(Z/Z_sun_) as an uncertain but plausible estimate of the mass of heavy elements that is not accreted by stars with giant planets, including our Sun. By combining our stellar evolution models to these estimates, we evaluate the consequences of planet formation on stellar surface compositions. We show that after the first ~0.1 million years (Myr) during which stellar structure can differ widely from the usually assumed fully-convective structure, the evolution of the convective zone follows classical pre-main-sequence evolutionary tracks within a factor of two in age. We find that planet formation should lead to a scatter in stellar surface composition that is larger for high-mass stars than for low-mass stars. We predict a spread in [Fe/H] of approximately 0.05dex for stars of temperature Teff~6500K, to 0.02dex for Teff~5500K, marginally compatible with differences in metallicities observed in some binary stars with planets. Stars with Teff>=7000K may show much larger [Fe/H] deficits, by 0.6dex or more, in the presence of efficient planet formation, compatible with the existence of refractory-poor lambda Boo stars. We also find that planet formation may explain the lack of refractory elements seen in the Sun as compared to solar twins, but only if the ice-to-rock ratio in the solar-system planets is less than ~0.4 and planet formation began less than ~1.3Myr after the beginning of the formation of the Sun.
- ID:
- ivo://CDS.VizieR/J/ApJS/199/38
- Title:
- Presupernova evolution
- Short Name:
- J/ApJS/199/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new set of zero metallicity models in the range 13-80M_{sun}_ together to the associated explosive nucleosynthesis. These models are fully homogeneous with the solar metallicity set we published in Limongi & Chieffi (2006ApJ...647..483L) and will be freely available at the Online Repository for the FRANEC Evolutionary Output (ORFEO) Web site. A comparison between these yields and an average star that represents the average behavior of most of the very metal-poor stars in the range -5.0<[Fe/H]<-2.5 confirms previous findings that only a fraction of the elemental [X/Fe] may be fitted by the ejecta of standard core collapse supernovae.
