- ID:
- ivo://CDS.VizieR/J/ApJ/888/34
- Title:
- Robo-AO Kepler asteroseismic survey. II.
- Short Name:
- J/ApJ/888/34
- Date:
- 25 Oct 2021 10:08:41
- Publisher:
- CDS
- Description:
- The Kepler Space Telescope observed over 15000 stars for asteroseismic studies. Of these, 75% of dwarfs (and 8% of giants) were found to show anomalous behavior, such as suppressed oscillations (low amplitude) or no oscillations at all. The lack of solar-like oscillations may be a consequence of multiplicity, due to physical interactions with spectroscopic companions or due to the dilution of oscillation amplitudes from "wide" (AO detected; visual) or spectroscopic companions introducing contaminating flux. We present a search for stellar companions to 327 of the Kepler asteroseismic sample, which were expected to display solar-like oscillations. We used direct imaging with Robo-AO, which can resolve secondary sources at ~0.15", and followed up detected companions with Keck AO. Directly imaged companion systems with both separations of <=0.5" and amplitude dilutions >10% all have anomalous primaries, suggesting these oscillation signals are diluted by a sufficient amount of excess flux. We also used the high-resolution spectrometer ESPaDOnS at the Canada-France-Hawai'i Telescope to search for spectroscopic binaries. We find tentative evidence for a higher fraction of spectroscopic binaries with high radial velocity scatter in anomalous systems, which would be consistent with previous results suggesting that oscillations are suppressed by tidal interactions in close eclipsing binaries.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/152/18
- Title:
- Robo-AO Kepler planetary candidate survey. II.
- Short Name:
- J/AJ/152/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We initiated the Robo-AO Kepler Planetary Candidate Survey in 2012 to observe each Kepler exoplanet candidate host star with high angular resolution, visible light, laser adaptive optics (AOs) imaging. Our goal is to find nearby stars lying in Kepler's photometric apertures that are responsible for the relatively high probability of false-positive exoplanet detections and that cause underestimates of the size of transit radii. Our comprehensive survey will also shed light on the effects of stellar multiplicity on exoplanet properties and will identify rare exoplanetary architectures. In this second part of our ongoing survey, we observed an additional 969 Kepler planet candidate hosts and we report blended stellar companions up to {Delta}m{approx}6 that contribute to Kepler's measured light curves. We found 203 companions within ~4'' of 181 of the Kepler stars, of which 141 are new discoveries. We measure the nearby star probability for this sample of Kepler planet candidate host stars to be 10.6%+/-1.1% at angular separations up to 2.5'', significantly higher than the 7.4%+/-1.0% probability discovered in our initial sample of 715 stars; we find the probability increases to 17.6%+/-1.5% out to a separation of 4.0''. The median position of Kepler Objects of Interest (KOIs) observed in this survey are 1.1{deg} closer to the galactic plane, which may account for some of the nearby star probability enhancement. We additionally detail 50 Keck AO images of Robo-AO observed KOIs in order to confirm 37 companions detected at a <5{sigma} significance level and to obtain additional infrared photometry on higher significance detected companions.
- ID:
- ivo://CDS.VizieR/J/ApJ/799/4
- Title:
- Robo-AO observations of binary stars
- Short Name:
- J/ApJ/799/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conducted a survey of nearby binary systems composed of main sequence stars of spectral types F and G in order to improve our understanding of the hierarchical nature of multiple star systems. Using Robo-AO, the first robotic adaptive optics instrument, we collected high angular resolution images with deep and well-defined detection limits in the Sloan Digital Sky Survey i' band. A total of 695 components belonging to 595 systems were observed. We prioritized observations of faint secondary components with separations over 10" to quantify the still poorly constrained frequency of their subsystems. Of the 214 secondaries observed, 39 contain such subsystems; 19 of those were discovered with Robo-AO. The selection-corrected frequency of secondary subsystems with periods from 10^3.5^ to 10^5^ days is 0.12+/-0.03, the same as the frequency of such companions to the primary. Half of the secondary pairs belong to quadruple systems where the primary is also a close pair, showing that the presence of subsystems in both components of the outer binary is correlated. The relatively large abundance of 2+2 quadruple systems is a new finding, and will require more exploration of the formation mechanism of multiple star systems. We also targeted close binaries with periods less than 100 yr, searching for their distant tertiary components, and discovered 17 certain and 2 potential new triples. In a subsample of 241 close binaries, 71 have additional outer companions. The overall frequency of tertiary components is not enhanced, compared to all (non-binary) targets, but in the range of outer periods from 10^6^ to 10^7.5^ days (separations on the order of 500AU), the frequency of tertiary components is 0.16+/-0.03, exceeding the frequency of similar systems among all targets (0.09) by almost a factor of two. Measurements of binary stars with Robo-AO allowed us to compute first orbits for 9 pairs and to improve orbits of another 11 pairs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/418/2074
- Title:
- Robust sample of galaxies at 6.0<z<8.7
- Short Name:
- J/MNRAS/418/2074
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a photometric redshift analysis designed to identify z>=6 galaxies from the near-infrared Hubble Space Telescope imaging in three deep fields [Hubble Ultra Deep Field (HUDF), HUDF09-2 and Early Release Science] covering a total area of 45 square arcmin. By adopting a rigorous set of criteria for rejecting low-redshift interlopers, and by employing a deconfusion technique to allow the available ultradeep IRAC imaging to be included in the candidate-selection process, we have derived a robust sample of 70 Lyman break galaxies (LBGs) spanning the redshift range 6.0<z<8.7.
- ID:
- ivo://CDS.VizieR/J/A+A/461/977
- Title:
- Rosat North Ecliptic survey stellar population
- Short Name:
- J/A+A/461/977
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- X-ray surveys are a very efficient mean of detecting young stars and therefore allow us to study the young stellar population in the solar neighborhood and the local star formation history in the last billion of years. We want to study the young stellar population in the solar neighborhood, to constrain its spatial density and scale height as well as the recent local star formation history. We analyze the stellar content of the ROSAT North Ecliptic Pole survey, and compare the observations with the predictions derived from stellar galactic model. Since the ROSAT NEP survey is sensitive at intermediate fluxes is able to sample both the youngest stars and the intermediate age stars (younger than 10^9^years), linking the shallow and deep flux surveys already published in the literature. We confirm the existence of an excess of yellow stars in our neighborhood previously seen in shallow survey, which is likely due to a young star population not accounted for in the model. However the excellent agreement between observations and predictions of dM stars casts some doubt on the real nature of this active population.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A108
- Title:
- Rosette globulettes and shells in the IR
- Short Name:
- J/A+A/567/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The compressed molecular shells around the central clusters in HII regions break up into morphologically distinct fragments due to the UV light from the central OB stars. Tiny, dense, sub-solar mass clumps called globulettes are one of such distinct features. The objective of this study is to study the globulettes and the shells in the Rosette Nebula. Their extinction, surface brightness in the cores and rims, and density have been estimated through NIR observations. The star-formation activity has also been studied. The NIR JHKs photometry is used in creating visual extinction maps and studying the density of individual globulettes.
2507. Rosette Nebula globules
- ID:
- ivo://CDS.VizieR/J/A+A/605/A82
- Title:
- Rosette Nebula globules
- Short Name:
- J/A+A/605/A82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Rosette nebula is an HII region ionized mainly by the stellar cluster NGC 2244. Elephant trunks, globules, and globulettes are seen at the interface where the HII region and the surrounding molecular shell meet. We have observed a field in the northwestern part of the Rosette nebula where we study the small globules protruding from the shell. Our aim is to measure their properties and study their star-formation history in continuation of our earlier study of the features of the region. We imaged the region in broadband near-infrared (NIR) JsHKs filters and narrowband H_2_ 1-0 S(1), P{beta}, and continuum filters using the SOFI camera at the ESO/NTT. The imaging was used to study the stellar population and surface brightness, create visual extinction maps, and locate star formation. Mid-infrared (MIR) Spitzer IRAC and WISE and optical NOT images were used to further study the star formation and the structure of the globules. The NIR and MIR observations indicate an outflow, which is confirmed with CO observations made with APEX.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A106
- Title:
- Rotational periods in Cygnus OB2
- Short Name:
- J/A+A/603/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a near-infrared time-series photometry study in the field of Cygnus OB2 association (RA~20.55h, DE~41.2{deg}). Observations were carried out in the JHK bands at the WFCAM/UKIRT telescope over 112 observed nights. We investigated the occurrence of periodicity in the time-series and we found reliable periods for 894 candidate members.
- ID:
- ivo://CDS.VizieR/J/ApJS/227/20
- Title:
- Rotation periods of asteroids using iPTF
- Short Name:
- J/ApJS/227/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to look for large super-fast rotators, in late 2014 and early 2015, five dedicated surveys covering ~188deg^2^ in the ecliptic plane have been carried out in the R-band, with ~10min cadence using the intermediate Palomar Transient Factory. Among 1029 reliable rotation periods obtained from the surveys, we discovered 1 new large super-fast rotator, (40511) 1999 RE88, and 18 other candidates. (40511) 1999 RE88 is an S-type inner main-belt asteroid with a diameter of D=1.9+/-0.3km, a rotation period of P=1.96+/-0.01hr, and a light curve amplitude of {Delta}m~1.0mag. To maintain such fast rotation, an internal cohesive strength of ~780Pa is required. Combining all known large super-fast rotators, their cohesive strengths all fall in the range of 100-1000Pa of lunar regolith. However, the number of large super-fast rotators seems to be far less than the whole asteroid population. This might indicate a peculiar asteroid group for them. Although the detection efficiency for a long rotation period is greatly reduced due to our two-day observation time span, the spin-rate distributions of this work show consistent results with Chang+ (2015, J/ApJS/219/27), after considering the possible observational bias in our surveys. It shows a number decrease with an increase of spin rate for asteroids with a diameter of 3<=D<=15km, and a number drop at a spin rate of f=5rev/day for asteroids with D<=3km.
- ID:
- ivo://CDS.VizieR/J/AJ/162/147
- Title:
- Rotation periods of 43 TOIs with Evryscope and TESS
- Short Name:
- J/AJ/162/147
- Date:
- 14 Mar 2022 06:47:58
- Publisher:
- CDS
- Description:
- Stellar radial-velocity (RV) jitter due to surface activity may bias the RV semiamplitude and mass of rocky planets. The amplitude of the jitter may be estimated from the uncertainty in the rotation period, allowing the mass to be more accurately obtained. We find candidate rotation periods for 17 out of 35 TESS Objects of Interest (TOI) hosting <3R{Earth} planets as part of the Magellan-TESS survey, which is the first-ever statistically robust study of exoplanet masses and radii across the photoevaporation gap. Seven periods are >~3{sigma} detections, two are >~1.5{sigma}, and eight show plausible variability, but the periods remain unconfirmed. The other 18 TOIs are nondetections. Candidate rotators include the host stars of the confirmed planets L168-9b, the HD21749 system, LTT1445Ab, TOI1062b, and the L98-59 system. Thirteen candidates have no counterpart in the 1000 TOI rotation catalog of Canto Martins et al. We find periods for G3-M3 dwarfs using combined light curves from TESS and the Evryscope all-sky array of small telescopes, sometimes with longer periods than would be possible with TESS alone. Secure periods range from 1.4 to 26 days with Evryscope-measured photometric amplitudes as small as 2.1mmag in g' . We also apply Monte Carlo sampling and a Gaussian process stellar activity model from exoplanet to the TESS light curves of six TOIs to confirm the Evryscope periods.
