- ID:
- ivo://CDS.VizieR/J/ApJ/746/15
- Title:
- Runaway massive stars from R136
- Short Name:
- J/ApJ/746/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conduct a theoretical study on the ejection of runaway massive stars from R136 -the central massive, starburst cluster in the 30 Doradus complex of the Large Magellanic Cloud. Specifically, we investigate the possibility of the very massive star (VMS) VFTS 682 being a runaway member of R136. Recent observations of the above VMS, by virtue of its isolated location and its moderate peculiar motion, have raised the fundamental question of whether isolated massive star formation is indeed possible. We perform the first realistic N-body computations of fully mass-segregated R136-type star clusters in which all the massive stars are in primordial binary systems. These calculations confirm that the dynamical ejection of a VMS from an R136-like cluster, with kinematic properties similar to those of VFTS 682, is common. Hence, the conjecture of isolated massive star formation is unnecessary to account for this VMS. Our results are also quite consistent with the ejection of 30 Dor 016, another suspected runaway VMS from R136. We further note that during the clusters' evolution, mergers of massive binaries produce a few single stars per cluster with masses significantly exceeding the canonical upper limit of 150 M_{sun}_. The observations of such single super-canonical stars in R136, therefore, do not imply an initial mass function with an upper limit greatly exceeding the accepted canonical 150M_{sun}_limit, as has been suggested recently, and they are consistent with the canonical upper limit.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/247/11
- Title:
- RV photon limits of well-characterized F-M stars
- Short Name:
- J/ApJS/247/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The determination of extrasolar planet masses with the radial velocity (RV) technique requires spectroscopic Doppler information from the planet's host star, which varies with stellar brightness and temperature. We analyze the Doppler information in spectra from dwarfs of spectral types F-M utilizing empirical information from HARPS and CARMENES data and model spectra. We revisit the question of whether optical or near-infrared instruments are more efficient for RV observations in low-mass stars, and we come to the conclusion that an optical setup (BVR bands) is more efficient than a near-infrared one (YJHK) in dwarf stars hotter than 3200K. We publish a catalog of 46480 well-studied F-M dwarfs in the solar neighborhood, and we compare its distribution to more than 1 million stars from Gaia DR2. For all stars, we estimate the RV photon noise achievable in typical observations under the assumption of no activity jitter and slow rotation. We find that with an ESPRESSO-like instrument at an 8m telescope, a photon noise limit of 10cm/s or lower can be reached in more than 280 stars in a 5 minute observation. At 4m telescopes, a photon noise limit of 1m/s can be reached in a 10 minute exposure in approximately 10000 predominantly Sun-like stars with a HARPS-like (optical) instrument. The same applies to ~3000 stars for a red optical setup that covers the R and I bands and ~700 stars for a near-infrared instrument. For the latter two, many of the targets are nearby M dwarfs. Finally, we identify targets in which Earth-mass planets within the liquid water habitable zone can cause RV amplitudes comparable to the RV photon noise. Assuming the same exposure times as above, we find that an ESPRESSO-like instrument can reach this limit for 1M_{Earth}_ planets in more than 1000 stars. The optical, red optical, and near-infrared configurations reach the limit for 2M_{Earth}_ planets in approximately 500, 700, and 200 stars, respectively. An online tool is provided to estimate the RV photon noise as a function of stellar temperature and brightness and wavelength coverage.
- ID:
- ivo://CDS.VizieR/J/ApJ/787/110
- Title:
- SAGA: Stromgren survey of seismic KIC stars
- Short Name:
- J/ApJ/787/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroseismology has the capability of precisely determining stellar properties that would otherwise be inaccessible, such as radii, masses, and thus ages of stars. When coupling this information with classical determinations of stellar parameters, such as metallicities, effective temperatures, and angular diameters, powerful new diagnostics for Galactic studies can be obtained. The ongoing Stromgren survey for Asteroseismology and Galactic Archaeology (SAGA) has the goal of transforming the Kepler field into a new benchmark for Galactic studies, similar to the solar neighborhood. Here we present the first results from a stripe centered at a Galactic longitude of 74{deg} and covering latitude from about 8{deg} to 20{deg}, which includes almost 1000 K giants with seismic information and the benchmark open cluster NGC 6819. We describe the coupling of classical and seismic parameters, the accuracy as well as the caveats of the derived effective temperatures, metallicities, distances, surface gravities, masses, and radii. Confidence in the achieved precision is corroborated by the detection of the first and secondary clumps in a population of field stars with a ratio of 2 to 1 and by the negligible scatter in the seismic distances among NGC 6819 member stars. An assessment of the reliability of stellar parameters in the Kepler Input Catalog is also performed, and the impact of our results for population studies in the Milky Way is discussed, along with the importance of an all-sky Stromgren survey.
- ID:
- ivo://CDS.VizieR/J/AJ/158/155
- Title:
- SB candidates from the RAVE & Gaia DR2 surveys
- Short Name:
- J/AJ/158/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The combination of the final version of the Radial Velocity Experiment (RAVE) spectroscopic survey data release 6 with radial velocities (RVs) and astrometry from Gaia DR2 (Cat. I/345) allows us to identify and create a catalog of single-lined binary star candidates (SB1), their inferred orbital parameters, and to inspect possible double-lined binary stars (SB2). A probability function for the detection of RV variations is used for identifying SB1 candidates. The estimation of orbital parameters for main-sequence dwarfs is performed by matching the measured RVs with theoretical velocity curves sampling the orbital parameter space. The method is verified by studying a mock sample from the SB 9 catalog (Cat. B/sb9). Studying the boxiness and asymmetry of the spectral lines allows us to identify possible SB2 candidates, while matching their spectra to a synthetic library indicates probable properties of their components. From the RAVE catalog we select 37664 stars with multiple RV measurements and identify 3838 stars as SB1 candidates. Joining RAVE and Gaia DR2 yields 450646 stars with RVs measured by both surveys and 27716 of them turn out to be SB1 candidates, which is an increase by an order of magnitude over previous studies. For main-sequence dwarf candidates we calculate their most probable orbital parameters: orbital periods are not longer than a few years and primary components have masses similar to the solar mass. All our results are available in the electronic version.
- ID:
- ivo://CDS.VizieR/J/AJ/162/259
- Title:
- Scaling K2. IV. Campaigns 1-8 & 10-18 planets sample
- Short Name:
- J/AJ/162/259
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- We provide the first full K2 transiting exoplanet sample, using photometry from Campaigns 1-8 and 10-18, derived through an entirely automated procedure. This homogeneous planet candidate catalog is crucial to perform a robust demographic analysis of transiting exoplanets with K2. We identify 747 unique planet candidates and 57 multiplanet systems. Of these candidates, 366 have not been previously identified, including one resonant multiplanet system and one system with two short-period gas giants. By automating the construction of this list, measurements of sample biases (completeness and reliability) can be quantified. We carried out a light-curve-level injection/recovery test of artificial transit signals and found a maximum completeness of 61%, a consequence of the significant detrending required for K2 data analysis. Through this operation we attained measurements of the detection efficiency as a function of signal strength, enabling future population analysis using this sample. We assessed the reliability of our planet sample by testing our vetting software EDI-Vetter against inverted transit-free light curves. We estimate that 91% of our planet candidates are real astrophysical signals, increasing up to 94% when limited to the FGKM dwarf stellar population. We also constrain the contamination rate from background eclipsing binaries to less than 5%. The presented catalog, along with the completeness and reliability measurements, enable robust exoplanet demographic studies to be carried out across the fields observed by the K2 mission for the first time.
- ID:
- ivo://CDS.VizieR/J/MNRAS/374/1413
- Title:
- SCUBA survey of Orion
- Short Name:
- J/MNRAS/374/1413
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have re-analysed all of the Submillimetre Common User Bolometer Array (SCUBA) archive data of the Orion star-forming regions. We have put together all of the data taken at different times by different groups. Consequently, we have constructed the deepest submillimetre maps of these regions ever made. There are four regions that have been mapped: Orion A North and South, and Orion B North and South. We find that two of the regions, Orion A North and Orion B North, have deeper sensitivity and completeness limits, and contain a larger number of sources, so we concentrate on these two. We compare the data with archive data from the Spitzer Space Telescope to determine whether or not a core detected in the submillimetre is pre-stellar in nature.
- ID:
- ivo://CDS.VizieR/J/ApJ/809/146
- Title:
- SDSS-DR8 isolated low-mass galaxies
- Short Name:
- J/ApJ/809/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the baryon content of low-mass galaxies selected from the Sloan Digital Sky Survey (SDSS DR8), focusing on galaxies in isolated environments where the complicating physics of galaxy-galaxy interactions are minimized. We measure neutral hydrogen (HI) gas masses and line widths for 148 isolated galaxies with stellar mass between 10^7^ and 10^9.5^M_{sun}_. We compare isolated low-mass galaxies to more massive galaxies and galaxies in denser environments by remeasuring HI emission lines from the Arecibo Legacy Fast ALFA survey 40% data release. All isolated low-mass galaxies either have large atomic gas fractions or large atomic gas fractions cannot be ruled out via their upper limits. We measure a median atomic gas fraction of f_gas_=0.81+/-0.13 for our isolated low-mass sample with no systems below 0.30. At all stellar masses, the correlations between galaxy radius, baryonic mass, and velocity width are not significantly affected by environment. Finally, we estimate a median baryon to total dynamical mass fraction of f_baryon,disk_=0.15+/-0.17. We also estimate two different median baryon to halo mass fractions using the results of semi-analytic models (f_baryon,disk_=0.04+/-0.06) and abundance matching (f_baryon,halo_=0.04+/-0.02). Baryon fractions estimated directly using HI observations appear independent of environment and maximum circular velocity, while baryon fractions estimated using abundance matching show a significant depletion of baryons at low maximum circular velocities.
- ID:
- ivo://CDS.VizieR/J/ApJS/194/42
- Title:
- SDSS-DR3 MgII-based black hole masses
- Short Name:
- J/ApJS/194/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present MgII-based black hole (BH) mass estimates for 27602 quasars with rest-frame UV spectra available in the Sloan Digital Sky Survey Data Release Three (Cat. II/259; superseded by II/294). This estimation is possible due to the existence of an empirical correlation between the radius of the broad-line region (BLR) and the continuum luminosity at 3000{AA}. We regenerate this correlation by applying our measurement method to UV spectra of low-redshift quasars in the Hubble Space Telescope/International Ultraviolet Explorer databases which have corresponding reverberation mapping estimates of the H{beta} BLR's radius. Our mass estimation method uses the line dispersion rather than the full width at half-maximum of the low-ionization MgII emission line.
- ID:
- ivo://CDS.VizieR/J/ApJ/680/169
- Title:
- SDSS DR5 virial black hole masses
- Short Name:
- J/ApJ/680/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compile black hole (BH) masses for ~60000 quasars in the redshift range 0.1~<z~<4.5 included in the Fifth Data Release of the Sloan Digital Sky Survey (Schneider et al. 2007, Cat. VII/252), using virial BH mass estimators based on the H{beta}, MgII, and CIV emission lines.
- ID:
- ivo://CDS.VizieR/J/ApJS/204/5
- Title:
- SDSS DR7 white dwarf catalog
- Short Name:
- J/ApJS/204/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of spectroscopically confirmed white dwarf stars from the Sloan Digital Sky Survey (SDSS) Data Release 7 spectroscopic catalog. We find 20407 white dwarf spectra, representing 19712 stars, and provide atmospheric model fits to 14120 DA and 1011 DB white dwarf spectra from 12843 and 923 stars, respectively. These numbers represent more than a factor of two increase in the total number of white dwarf stars from the previous SDSS white dwarf catalogs based on DR4 data. Our distribution of subtypes varies from previous catalogs due to our more conservative, manual classifications of each star in our catalog, supplementing our automatic fits. In particular, we find a large number of magnetic white dwarf stars whose small Zeeman splittings mimic increased Stark broadening that would otherwise result in an overestimated logg if fit as a non-magnetic white dwarf. We calculate mean DA and DB masses for our clean, non-magnetic sample and find the DB mean mass is statistically larger than that for the DAs.
