- ID:
- ivo://CDS.VizieR/J/AJ/154/184
- Title:
- Multiplicity of RV exoplanet host stars
- Short Name:
- J/AJ/154/184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Given the frequency of stellar multiplicity in the solar neighborhood, it is important to study the impacts this can have on exoplanet properties and orbital dynamics. There have been numerous imaging survey projects established to detect possible low-mass stellar companions to exoplanet host stars. Here, we provide the results from a systematic speckle imaging survey of known exoplanet host stars. In total, 71 stars were observed at 692 and 880 nm bands using the Differential Speckle Survey Instrument at the Gemini-north Observatory. Our results show that all but two of the stars included in this sample have no evidence of stellar companions with luminosities down to the detection and projected separation limits of our instrumentation. The mass-luminosity relationship is used to estimate the maximum mass a stellar companion can have without being detected. These results are used to discuss the potential for further radial velocity follow-up and interpretation of companion signals.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/156/148
- Title:
- Multiwavelength photometry of RCB stars
- Short Name:
- J/AJ/156/148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of extended, cold dust envelopes surrounding R Coronae Borealis (RCB) stars began with their discovery by the Infrared Astronomical Satellite. RCB stars are carbon-rich supergiants characterized by their extreme hydrogen deficiency and their irregular and spectacular declines in brightness (up to 9 mag). We have analyzed new and archival Spitzer Space Telescope and Herschel Space Observatory data of the envelopes of seven RCB stars to examine the morphology and investigate the origin of these dusty shells. Herschel, in particular, has revealed the first-ever bow shock associated with an RCB star with its observations of SU Tauri. These data have allowed the assembly of the most comprehensive spectral energy distributions (SEDs) of these stars with multiwavelength data from the ultraviolet to the submillimeter. Radiative transfer modeling of the SEDs implies that the RCB stars in this sample are surrounded by an inner warm (up to 1200 K) and an outer cold (up to 200 K) envelope. The outer shells are suggested to contain up to 10^-3^ M_{sun}_ of dust and have existed for up to 10^5^ years depending on the expansion rate of the dust. This age limit indicates that these structures have most likely been formed during the RCB phase.
- ID:
- ivo://CDS.VizieR/J/A+A/539/A143
- Title:
- Nearby B-stars stellar parameters and abundances
- Short Name:
- J/A+A/539/A143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Early B-type stars are ideal indicators for present-day cosmic abundances since they preserve their pristine abundances and typically do not migrate far beyond their birth environments over their short lifetimes, in contrast to older stars like the Sun. They are also unaffected by depletion onto dust grains, unlike the cold/warm interstellar medium (ISM) or HII regions. A carefully selected sample of early B-type stars in OB associations and the field within the solar neighbourhood is studied comprehensively. Quantitative spectroscopy is used to characterise their atmospheric properties in a self-consistent way. Present-day abundances for the astrophysically most interesting chemical elements are derived in order to investigate whether a present-day cosmic abundance standard can be established.
- ID:
- ivo://CDS.VizieR/J/AJ/123/2806
- Title:
- Nearby stars in the NLTT catalogue
- Short Name:
- J/AJ/123/2806
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are currently undertaking a program aimed at identifying previously unrecognized late-type dwarfs within 20pc of the Sun. As a first step, we have cross-referenced Luyten's NLTT proper-motion catalog (Cat. <I/98>) against the second incremental release of the Two Micron All Sky Survey (2MASS) Point Source Catalog (Cat. <B/2mass>) and use optical/infrared colors, derived by combining Luyten's m_r_ estimates with 2MASS data, to identify candidate nearby stars. This paper describes the definition of a reference sample of 1245 stars and presents a compilation of literature data for more than one-third of the sample. Only 274 stars have trigonometric parallax measurements, but we have used data for nearby stars with well-determined trigonometric parallaxes to compute color-magnitude relations in the (M_V_, V-K), (M_V_, V-I), and (M_I_, I-J) planes and use those relations to determine photometric parallaxes for NLTT stars with optical photometry. Based on the 2MASS JHKs data alone, we have identified a further 42 ultracool dwarfs (J-Ks>0.99) and use J-Ks colors to estimate photometric parallaxes. Combining these various techniques, we identify 308 stars with formal distances of less than 20 pc, while a further 46 have distance estimates within 1{sigma} of survey limit. Of these 354 stars, 75, including 39 of the ultracool dwarfs, are new to nearby-star catalogs. Two stars with both optical and near-infrared photometry are potential additions to the immediate solar neighborhood, with formal distance estimates of less than 10 pc.
- ID:
- ivo://CDS.VizieR/J/AJ/153/25
- Title:
- Near-infrared observations of 84 KOI systems
- Short Name:
- J/AJ/153/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine probabilities of physical association for stars in blended Kepler Objects of Interest (KOIs), and find that 14.5%_-3.4%_^+3.8%^ of companions within ~4'' are consistent with being physically unassociated with their primary. This produces a better understanding of potential false positives in the Kepler catalog and will guide models of planet formation in binary systems. Physical association is determined through two methods of calculating multi-band photometric parallax using visible and near-infrared adaptive optics observations of 84 KOI systems with 104 contaminating companions within ~4''. We find no evidence that KOI companions with separations of less than 1'' are more likely to be physically associated than KOI companions generally. We also reinterpret transit depths for 94 planet candidates, and calculate that 2.6%+/-0.4% of transits have R>15R_{oplus}_, which is consistent with prior modeling work.
- ID:
- ivo://CDS.VizieR/J/MNRAS/399/1709
- Title:
- Near-infrared survey of Miras
- Short Name:
- J/MNRAS/399/1709
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a near-infrared survey for long-period variables in a field of view of 20x30arcmin^2^ towards the Galactic Centre (GC). We have detected 1364 variables, of which 348 are identified with those reported in Glass et al. (2001. Cat. <J/MNRAS/321/77>). We present a catalogue and photometric measurements for the detected variables and discuss their nature.
- ID:
- ivo://CDS.VizieR/J/AJ/154/195
- Title:
- New binaries in the {epsilon} Cha association
- Short Name:
- J/AJ/154/195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Adaptive Optics-aided speckle observations of 47 young stars in the {epsilon} Cha association made at the 4 m Southern Astrophysical Research Telescope in the I-band. We resolved 10 new binary pairs, 5 previously known binaries, and 2 triple systems, also previously known. In the separation range between 4 and 300 au, the 30 association members of spectral types G0 and later host 6 binary companions, leading to the raw companion frequency of 0.010+/-0.04 per decade of separation, comparable to the main sequence dwarfs in the field. On the other hand, all five massive association members of spectral types A and B have companions in this range. We discuss the newly resolved and known binaries in our sample. Observed motions in the triple system {epsilon} Cha, composed of three similar B9V stars, can be described by tentative orbits with periods 13 and ~900 years and a large mutual inclination.
- ID:
- ivo://CDS.VizieR/J/MNRAS/383/831
- Title:
- New DENIS nearby L and late-M dwarfs
- Short Name:
- J/MNRAS/383/831
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on new nearby L and late-M dwarfs (d_phot_<=30pc) discovered in our search for nearby ultracool dwarfs (I-J>=3.0, later than M8.0) in the Galactic plane (|b|<15{deg}) over 4800 deg^2^ in the Deep Near Infrared Survey of t he Southern Sky (DENIS) data base. We used late-M (>=M8.0), L and T dwarfs with accurate trigonometric parallaxes to calibrate the M_J_ versus I-J colour-luminosity relation. The resulting photometric distances have standard errors of ~15 per cent, which we used to select candidates dphot <=30pc. We measured proper motions from multi-epoch images found in the public archives ALADIN, DSS, 2MASS and DENIS, with at least three distinct epochs and time baselines of 10-21yr. We then used the Maximum Reduced Proper Motion method to select 28 candidates as ultracool dwarfs (M8.0-L8.0) and to reject one as a distant red star. Our low-resolution optical spectra confirmed that 26 were indeed ultracool dwarfs, with spectral types from M8.0 to L5.5. Two contaminants and one rejected by the maximum reduced proper motion cut-off were all reddened F-K main sequence stars. 20 of these 26 ultracool dwarfs are new nearby ultracool dwarf members, three L dwarfs within 15pc with one L3.5 at only ~10pc.
- ID:
- ivo://CDS.VizieR/J/AJ/142/92
- Title:
- New proper motion stars with pm>=0.18"/yr
- Short Name:
- J/AJ/142/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here we present 1584 new southern proper motion systems with {mu}>=0.18"/yr and 16.5>R_59F_>=18.0. This search complements the six previous SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky for stars within the same proper motion range, but with R_59F_<=16.5. As in previous papers, we present distance estimates for these systems and find that three systems are estimated to be within 25pc, including one, SCR 1546-5534, possibly within the RECONS 10pc horizon at 6.7pc, making it the second nearest discovery of the searches. We find 97 white dwarf candidates with distance estimates between 10 and 120pc, as well as 557 cool subdwarf candidates.
- ID:
- ivo://CDS.VizieR/J/AJ/142/10
- Title:
- New proper motion stars 0.40"/yr>pm>=0.18"/yr
- Short Name:
- J/AJ/142/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 2817 new southern proper motion systems with 0.40"/yr>{mu}>=0.18"/yr and declination between -47{deg} and 00{deg}. This is a continuation of the SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky. We use the same photometric relations as previous searches to provide distance estimates based on the assumption that the objects are single main-sequence stars. We find 79 new red dwarf systems predicted to be within 25pc, including a few new components of previously known systems.
