- ID:
- ivo://CDS.VizieR/J/A+A/585/A73
- Title:
- PTPS stars. III. The evolved stars sample
- Short Name:
- J/A+A/585/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the complete spectroscopic analysis of 455 stars observed within the Penn State - Torun Centre for Astronomy Planet Search (PTPS) with the High Resolution Spectrograph of the 9.2m Hobby-Eberly Telescope. We also present the total sample of 744 evolved stars of the PTPS and discuss masses of stellar hosts in our and other surveys devoted to evolved planetary systems. Stellar atmospheric parameters were determined through a strictly spectroscopic LTE analysis of equivalent widths of FeI and FeII lines. Rotational velocities were obtained from fitting synthetic spectra. Radial velocities were obtained from fitting a Gaussian function to the cross-correlation function. We determined stellar masses, ages, and luminosities with a Bayesian analysis of theoretical isochrones. The radii were calculated either from derived masses and logg or from Teff and luminosities.
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412. PTPS stars IV.
- ID:
- ivo://CDS.VizieR/J/A+A/615/A31
- Title:
- PTPS stars IV.
- Short Name:
- J/A+A/615/A31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our knowledge of the intrinsic parameters of exoplanets is as precise as our determinations of their stellar hosts parameters. In the case of radial velocity searches for planets, stellar masses appear to be crucial. But before estimating stellar masses properly, detailed spectroscopic analysis is essential. With this paper we conclude a general spectroscopic description of the Pennsylvania-Torun Planet Search (PTPS) sample of stars. We aim at a detailed description of basic parameters of stars representing the complete PTPS sample. We present atmospheric and physical parameters for dwarf stars observed within the PTPS along with updated physical parameters for the remaining stars from this sample after the first Gaia data release. We used high resolution (R=60000) and high signal-to-noise-ratio (S/N=150-250) spectra from the Hobby-Eberly Telescope and its High Resolution Spectrograph. Stellar atmospheric parameters were determined through a strictly spectroscopic local thermodynamic equilibrium analysis (LTE) of the equivalent widths of FeI and FeII lines. Stellar masses, ages, and luminosities were estimated through a Bayesian analysis of theoretical isochrones.
- ID:
- ivo://CDS.VizieR/J/ApJS/232/23
- Title:
- 27 pulsating DA WDs follow-up observations
- Short Name:
- J/ApJS/232/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry and spectroscopy for 27 pulsating hydrogen-atmosphere white dwarfs (DAVs; a.k.a. ZZ Ceti stars) observed by the Kepler space telescope up to K2 Campaign 8, an extensive compilation of observations with unprecedented duration (>75 days) and duty cycle (>90%). The space-based photometry reveals pulsation properties previously inaccessible to ground- based observations. We observe a sharp dichotomy in oscillation mode line widths at roughly 800s, such that white dwarf pulsations with periods exceeding 800s have substantially broader mode line widths, more reminiscent of a damped harmonic oscillator than a heat-driven pulsator. Extended Kepler coverage also permits extensive mode identification: we identify the spherical degree of 87 out of 201 unique radial orders, providing direct constraints of the rotation period for 20 of these 27 DAVs, more than doubling the number of white dwarfs with rotation periods determined via asteroseismology. We also obtain spectroscopy from 4m-class telescopes for all DAVs with Kepler photometry. Using these homogeneously analyzed spectra, we estimate the overall mass of all 27 DAVs, which allows us to measure white dwarf rotation as a function of mass, constraining the endpoints of angular momentum in low- and intermediate-mass stars. We find that 0.51-0.73M{sun} white dwarfs, which evolved from 1.7-3.0M{sun} ZAMS progenitors, have a mean rotation period of 35hr with a standard deviation of 28hr, with notable exceptions for higher-mass white dwarfs.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/244
- Title:
- Pulse profiles for simulated thermonuclear bursts
- Short Name:
- J/ApJ/833/244
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The equation of state of cold supra-nuclear-density matter, such as in neutron stars, is an open question in astrophysics. A promising method for constraining the neutron star equation of state is modeling pulse profiles of thermonuclear X-ray burst oscillations from hot spots on accreting neutron stars. The pulse profiles, constructed using spherical and oblate neutron star models, are comparable to what would be observed by a next-generation X-ray timing instrument like ASTROSAT, NICER, or a mission similar to LOFT. In this paper, we showcase the use of an evolutionary optimization algorithm to fit pulse profiles to determine the best-fit masses and radii. By fitting synthetic data, we assess how well the optimization algorithm can recover the input parameters. Multiple Poisson realizations of the synthetic pulse profiles, constructed with 1.6 million counts and no background, were fitted with the Ferret algorithm to analyze both statistical and degeneracy-related uncertainty and to explore how the goodness of fit depends on the input parameters. For the regions of parameter space sampled by our tests, the best-determined parameter is the projected velocity of the spot along the observer's line of sight, with an accuracy of <=3% compared to the true value and with <=5% statistical uncertainty. The next best determined are the mass and radius; for a neutron star with a spin frequency of 600Hz, the best-fit mass and radius are accurate to <=5%, with respective uncertainties of <=7% and <=10%. The accuracy and precision depend on the observer inclination and spot colatitude, with values of ~1% achievable in mass and radius if both the inclination and colatitude are >~60deg.
- ID:
- ivo://CDS.VizieR/J/ApJ/870/1
- Title:
- PUSH CCSN to explosions in spherical symmetry. II.
- Short Name:
- J/ApJ/870/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a previously presented proof-of-principle study, we established a parameterized spherically symmetric explosion method (PUSH) that can reproduce many features of core-collapse supernovae (CCSN). The present paper goes beyond a specific application that is able to reproduce observational properties of SN1987A and performs a systematic study of an extensive set of nonrotating, solar metallicity stellar progenitor models in the mass range from 10.8 to 120M_{sun}_. This includes the transition from neutron stars to black holes as the final result of the collapse of massive stars, and the relation of the latter to supernovae, possibly faint supernovae, and failed supernovae. We discuss the explosion properties of all models and predict remnant mass distributions within this approach. The present paper provides the basis for extended nucleosynthesis predictions in a forthcoming paper to be employed in galactic evolution models.
- ID:
- ivo://CDS.VizieR/J/AJ/154/216
- Title:
- Radial velocities of 41 Kepler eclipsing binaries
- Short Name:
- J/AJ/154/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eclipsing binaries are vital for directly determining stellar parameters without reliance on models or scaling relations. Spectroscopically derived parameters of detached and semi-detached binaries allow us to determine component masses that can inform theories of stellar and binary evolution. Here we present moderate resolution ground-based spectra of stars in close binary systems with and without (detected) tertiary companions observed by NASA's Kepler mission and analyzed for eclipse timing variations. We obtain radial velocities and spectroscopic orbits for five single-lined and 35 double-lined systems, and confirm one false positive eclipsing binary. For the double-lined spectroscopic binaries, we also determine individual component masses and examine the mass ratio M_2_/M_1_ distribution, which is dominated by binaries with like-mass pairs and semi-detached classical Algol systems that have undergone mass transfer. Finally, we constrain the mass of the tertiary component for five double-lined binaries with previously detected companions.
- ID:
- ivo://CDS.VizieR/J/AJ/145/41
- Title:
- Radial velocities of 33 spectroscopic binaries
- Short Name:
- J/AJ/145/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orbital elements of 37 single-lined spectroscopic binary systems (SB1s) and 5 double-lined spectroscopic binary systems (SB2s) were determined using high-dispersion spectroscopy. To determine the orbital elements accurately, we carried out precise Doppler shift measurements using the HIgh Dispersion Echelle Spectrograph mounted on the Okayama Astrophysical Observatory 1.88 m telescope. We achieved a radial-velocity precision of ~10 m.s^-1^ over seven years of observations. The targeted binaries have spectral types between F5 and K3, and are brighter than the 7th magnitude in the V band. The orbital elements of 28 SB1s and 5 SB2s were determined at least 10 times more precisely than previous measurements. Among the remaining nine SB1s, five objects were found to be single stars, and the orbital elements of four objects were not determined because our observations did not cover the entire orbital period. We checked the absorption lines from the secondary star for 28 SB1s and found that three objects were in fact SB2s.
- ID:
- ivo://CDS.VizieR/J/AJ/157/91
- Title:
- Radial velocities of subsystems in multiple stars
- Short Name:
- J/AJ/157/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic orbits are determined for inner subsystems in nine stellar hierarchies (HIP 2863, 4974, 8353, 28796, 35261, 92929, 115272, 115552, and 117596). Their periods range from 2.5 to 312 days. For each system, estimates of masses, orbital inclination, and other parameters are given.
- ID:
- ivo://CDS.VizieR/J/AJ/156/82
- Title:
- Radial velocity characterization of TESS planets
- Short Name:
- J/AJ/156/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) will conduct a two-year wide-field survey searching for transiting planets around bright stars. Many TESS discoveries will be amenable to mass characterization via ground-based radial velocity measurements with any of a growing suite of existing and anticipated velocimeters in the optical and near-infrared. In this study we present an analytical formalism to compute the number of radial velocity (RV) measurements - and hence the total observing time-required to characterize RV planet masses with the inclusion of either a white or correlated noise activity model. We use our model to calculate the total observing time required to measure all TESS planet masses from the expected TESS planet yield while relying on our current understanding of the targeted stars, stellar activity, and populations of unseen planets that inform the expected RV precision. We also present specialized calculations applicable to a variety of interesting subsets of TESS planets including the characterization of 50 planets smaller than 4 Earth radii, which is expected to take as little as 60 nights of observation. However, the efficient RV characterization of such planets requires a priori knowledge of the "best" targets, which we argue can be identified prior to the conclusion of the TESS planet search based on our calculations. Our results highlight the comparable performance of optical and near-IR spectrographs for most planet populations except for Earths and temperate TESS planets, which are more efficiently characterized in the near-IR. Lastly, we present an online tool to the community to compute the total observing times required to detect any transiting planet using a user-defined spectrograph (RVFC; http://maestria.astro.umontreal.ca/rvfc).
- ID:
- ivo://CDS.VizieR/J/AJ/157/52
- Title:
- Radial velocity observations in super-Earth systems
- Short Name:
- J/AJ/157/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use radial velocity (RV) observations to search for long-period gas giant companions in systems hosting inner super-Earth (1-4 R_{Earth}_, 1-10 M_{Earth}_) planets to constrain formation and migration scenarios for this population. We consistently refit published RV data sets for 65 stars and find nine systems with statistically significant trends indicating the presence of an outer companion. We combine these RV data with AO images to constrain the masses and semi-major axes of these companions. We quantify our sensitivity to the presence of long-period companions by fitting the sample with a power-law distribution and find an occurrence rate of 39%+/-7% for companions 0.5-20 M_Jup_ and 1-20 au. Half of our systems were discovered by the transit method, and half were discovered by the RV method. While differences in the RV baselines and number of data points between the two samples lead to different sensitivities to distant companions, we find that occurrence rates of gas giant companions in each sample are consistent at the 0.5{sigma} level. We compare the frequency of Jupiter analogs in these systems to the equivalent rate from field star surveys and find that Jupiter analogs are more common around stars hosting super-Earths. We conclude that the presence of outer gas giants does not suppress the formation of inner super-Earths, and that these two populations of planets instead appear to be correlated. We also find that the stellar metallicities of systems with gas giant companions are higher than those without companions, in agreement with the well-established metallicity correlation from RV surveys of field stars.
