- ID:
- ivo://CDS.VizieR/J/AJ/143/67
- Title:
- SLoWPoKES. II. Properties of wide, low-mass binaries
- Short Name:
- J/AJ/143/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results from spectroscopic observations of 113 ultra-wide, low-mass binary systems, largely composed of M0-M3 dwarfs, from the SLoWPoKES catalog of common proper motion pairs identified in the Sloan Digital Sky Survey (Dhital et al., 2010, Cat. J/AJ/139/2566). Radial velocities of each binary member were used to confirm that they are comoving and, consequently, to further validate the high fidelity of the SLoWPoKES catalog. Ten stars appear to be spectroscopic binaries based on broad or split spectral features, supporting previous findings that wide binaries are likely to be hierarchical systems. We measured the H{alpha} equivalent width of the stars in our sample and found that components of 81% of the observed pairs have similar H{alpha} levels. The difference in H{alpha} equivalent width among components with similar masses was smaller than the range of H{alpha} variability for individual objects. We confirm that the Lepine et al. (2007ApJ...669.1235L) {zeta}-index traces iso-metallicity loci for most of our sample of M dwarfs. However, we find a small systematic bias in {zeta}, especially in the early-type M dwarfs. We use our sample to recalibrate the definition of {zeta}. While representing a small change in the definition, the new {zeta} is a significantly better predictor of iso-metallicity for the higher-mass M dwarfs.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/763/L26
- Title:
- SMARTS observations of eps Eridani
- Short Name:
- J/ApJ/763/L26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The active K2 dwarf {epsilon} Eri has been extensively characterized both as a young solar analog and more recently as an exoplanet host star. As one of the nearest and brightest stars in the sky, it provides an unparalleled opportunity to constrain stellar dynamo theory beyond the Sun. We confirm and document the 3-year magnetic activity cycle in {epsilon} Eri originally reported by Hatzes and coworkers (2000ApJ...544L.145H), and we examine the archival data from previous observations spanning 45 years. The data show coexisting 3-year and 13-year periods leading into a broad activity minimum that resembles a Maunder minimum-like state, followed by the resurgence of a coherent 3-year cycle. The nearly continuous activity record suggests the simultaneous operation of two stellar dynamos with cycle periods of 2.95+/-0.03yr and 12.7+/-0.3 years, which, by analogy with the solar case, suggests a revised identification of the dynamo mechanisms that are responsible for the so-called "active" and "inactive" sequences as proposed by B\"ohm-Vitense (2007ApJ...657..486B). Finally, based on the observed properties of {epsilon} Eri, we argue that the rotational history of the Sun is what makes it an outlier in the context of magnetic cycles observed in other stars (as also suggested by its Li depletion), and that a Jovian-mass companion cannot be the universal explanation for the solar peculiarities.
- ID:
- ivo://CDS.VizieR/J/ApJS/215/15
- Title:
- SMaSH+: observations and companion detection
- Short Name:
- J/ApJS/215/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multiplicity is one of the most fundamental observable properties of massive O-type stars and offers a promising way to discriminate between massive star formation theories. Nevertheless, companions at separations between 1 and 100 milliarcsec (mas) remain mostly unknown due to intrinsic observational limitations. At a typical distance of 2kpc, this corresponds to projected physical separations of 2-200AU. The Southern MAssive Stars at High angular resolution survey (SMaSH+) was designed to fill this gap by providing the first systematic interferometric survey of Galactic massive stars. We observed 117 O-type stars with VLTI/PIONIER and 162 O-type stars with NACO/Sparse Aperture Masking (SAM), probing the separation ranges 1-45 and 30-250mas and brightness contrasts of {Delta}H<4 and {Delta}H<5, respectively. Taking advantage of NACO's field of view, we further uniformly searched for visual companions in an 8" radius down to {Delta}H=8. This paper describes observations and data analysis, reports the discovery of almost 200 new companions in the separation range from 1mas to 8" and presents a catalog of detections, including the first resolved measurements of over a dozen known long-period spectroscopic binaries. Excluding known runaway stars for which no companions are detected, 96 objects in our main sample ({delta}<0{deg}; H<7.5) were observed both with PIONIER and NACO/SAM. The fraction of these stars with at least one resolved companion within 200mas is 0.53. Accounting for known but unresolved spectroscopic or eclipsing companions, the multiplicity fraction at separation {rho}<8" increases to f_m_=0.91+/-0.03. The nine non-thermal radio emitters observed by SMaSH+ are all resolved, including the newly discovered pairs HD 168112 and CPD-47{deg}2963.
- ID:
- ivo://CDS.VizieR/J/A+A/625/L8
- Title:
- SN 2017jfs optical and NIR light curves
- Short Name:
- J/A+A/625/L8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of our photometric and spectroscopic follow-up of the intermediate-luminosity optical transient AT 2017jfs. At peak, the object reaches an absolute magnitude of Mg=-15.46+/-0.15mag and a bolometric luminosity of 5.5x10^41^erg/s. Its light curve has the double-peak shape typical of luminous red novae (LRNe), with a narrow first peak bright in the blue bands, while the second peak is longer-lasting and more luminous in the red and near-infrared (NIR) bands. During the first peak, the spectrum shows a blue continuum with narrow emission lines of H and FeII. During the second peak, the spectrum becomes cooler, resembling that of a K-type star, and the emission lines are replaced by a forest of narrow lines in absorption. About 5 months later, while the optical light curves are characterized by a fast linear decline, the NIR ones show a moderate rebrightening, observed until the transient disappears in solar conjunction. At these late epochs, the spectrum becomes reminiscent of that of M-type stars, with prominent molecular absorption bands. The late-time properties suggest the formation of some dust in the expanding common envelope or an IR echo from foreground pre-existing dust. We propose that the object is a common-envelope transient, possibly the outcome of a merging event in a massive binary, similar to NGC4490-2011OT1.
- ID:
- ivo://CDS.VizieR/J/AJ/160/7
- Title:
- 2019 SOAR speckle interferometry of binary stars
- Short Name:
- J/AJ/160/7
- Date:
- 09 Dec 2021
- Publisher:
- CDS
- Description:
- The results of speckle-interferometric observations at the 4.1m Southern Astrophysical Research Telescope in 2019 are given, totaling 2555 measurements of 1972 resolved pairs with separations from 15mas (median 0.21") and magnitude difference up to 6mag, and non-resolutions of 684 targets. We resolved for the first time 90 new pairs or subsystems in known binaries. This work continues our long-term speckle program. Its main goal is to monitor orbital motion of close binaries, including members of high-order hierarchies and Hipparcos pairs in the solar neighborhood. We give a list of 127 orbits computed using our latest measurements. Their quality varies from excellent (25 orbits of grades 1 and 2) to provisional (47 orbits of grades 4 and 5).
1046. SOAR TESS survey. I.
- ID:
- ivo://CDS.VizieR/J/AJ/159/19
- Title:
- SOAR TESS survey. I.
- Short Name:
- J/AJ/159/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) is finding transiting planet candidates around bright, nearby stars across the entire sky. The large field of view, however, results in low spatial resolution; therefore, multiple stars contribute to almost every TESS light curve. High angular resolution imaging can detect the previously unknown companions to planetary candidate hosts that dilute the transit depths, lead to host star ambiguity, and, in some cases, are the source of false-positive transit signals. We use speckle imaging on the Southern Astrophysical Research (SOAR) telescope to search for companions to 542 TESS planet candidate hosts in the southern sky. We provide correction factors for the 117 systems with resolved companions due to photometric contamination. The contamination in TESS due to close binaries is similar to that found in surveys of Kepler planet candidates. For the solar-type population, we find a deep deficit of close binary systems with projected stellar separations less than 100 au among planet candidate hosts (44 observed binaries compared to 124 expected based on field binary statistics). The close binary suppression among TESS planet candidate hosts is similar to that seen for the more distant Kepler population. We also find a large surplus of TESS planet candidates in wide binary systems detected in both SOAR and Gaia DR2 (Cat. I/345) (119 observed binaries compared to 77 expected). These wide binaries almost exclusively host giant planets, however, suggesting that orbital migration caused by perturbations from the stellar companion may lead to planet-planet scattering and suppress the population of small planets in wide binaries. Both trends are also apparent in the M dwarf planet candidate hosts.
- ID:
- ivo://CDS.VizieR/J/AJ/162/192
- Title:
- SOAR TESS survey. II. Impact of stellar companions
- Short Name:
- J/AJ/162/192
- Date:
- 14 Mar 2022 06:53:02
- Publisher:
- CDS
- Description:
- We present the results of the second year of exoplanet candidate host speckle observations from the SOAR TESS survey. We find 89 of the 589 newly observed TESS planet candidate hosts have companions within 3", resulting in light-curve dilution, that, if not accounted for, leads to underestimated planetary radii. We combined these observations with those from PaperI to search for evidence of the impact binary stars have on planetary systems. Removing the one-quarter of the targets observed identified as false-positive planet detections, we find that transiting planets are suppressed by nearly a factor of seven in close solar-type binaries, nearly twice the suppression previously reported. The result on planet occurrence rates that are based on magnitude-limited surveys is an overestimation by a factor of two if binary suppression is not taken into account. We also find tentative evidence for similar close binary suppression of planets in M-dwarf systems. Last, we find that the high rates of widely separated companions to hot Jupiter hosts previously reported was likely a result of false-positive contamination in our sample.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A135
- Title:
- Sodium detection in WASP-69b atmosphere
- Short Name:
- J/A+A/608/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the transmission spectrum around the Na I doublet at 589nm of the extrasolar planet WASP-69b, and compare the analysis to that of the well-know hot Jupiter HD 189733b. We also present the analysis of the Rossiter-McLaughlin (RM) effect for WASP-69b. We observed two transits of WASP-69b with the HARPS-North spectrograph (R=115 000) at the TNG telescope. We perform a telluric contamination subtraction based on the comparison between the observed spectra and a telluric water model. Then, the common steps of the differential spectroscopy are followed to extract the transmission spectrum. The method is tested with archival transit data of the extensively studied exoplanet HD 189733b, obtained with the HARPS-South spectrograph at ESO 3.6m telescope, and then applied to WASP-69b data. For HD 189733b, we spectrally resolve the NaI doublet and measure line contrasts of 0.72+/-0.05% (D2) and 0.51+/-0.05% (D1), and FWHMs of 0.64+/-0.04{AA} (D2) and 0.60+/-0.06{AA} (D1), in agreement with previously published results. For WASP-69b only the contrast of the D2 line can be measured (5.8+/-0.3%). This corresponds to a detection at the 5sigma-level of excess absorption of 0.5+/-0.1% in a passband of 1.5{AA}. By measuring the RM effect, we get an angular rotation of 0.24^+0.02^_-0.01_rad/day and a sky-projected angle between the stellar rotation axis and the normal of orbit plane of 0.4^+2.0^_-1.9_{deg} FOR wasP-69b. Similar results to those previously presented in the literature are obtained for the RM analysis of HD 189733b.
- ID:
- ivo://CDS.VizieR/J/A+A/552/A78
- Title:
- Solar like stars radial velocities
- Short Name:
- J/A+A/552/A78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 1992 we began a precision radial velocity (RV) survey for planets around solar-like stars with the Coude Echelle Spectrograph and the Long Camera (CES LC) at the 1.4m telescope in La Silla (Chile). We have continued the survey with the upgraded CES Very Long Camera (VLC) and HARPS, both at the 3.6m telescope, until 2007. The observations for 31 stars cover a time span of up to 15 years and the RV precision permit a search for Jupiter analogues. We perform a joint analysis for variability, trends, periodicities, and Keplerian orbits and compute detection limits. Moreover, the HARPS RVs are analysed for correlations with activity indicators (CaII H&K and CCF shape). We achieve a long-term RV precision of 15m/s (CES+LC, 1992-1998), 9m/s (CES+VLC, 1999-2006), and 2.8m/s (HARPS, 2003-2009, including archive data), resp. This enables us to confirm the known planets around Iota Hor, HR 506, and HR 3259. A steady RV trend for Eps Ind A can be explained by a planetary companion. On the other hand, we find previously reported trends to be smaller for Beta Hyi and not present for Alp Men. The candidate planet Eps Eri b was not detected despite our better precision. Also the planet announced for HR 4523 cannot be confirmed. Long-term trends in several of our stars are compatible with known stellar companions. We provide a spectroscopic orbital solution for the binary HR 2400 and refined solutions for the planets around HR 506 and Iota Hor. For some other stars the variations could be attributed to stellar activity.
- ID:
- ivo://CDS.VizieR/J/AJ/144/64
- Title:
- Solar neighborhood. XXVIII. Substellar companions
- Short Name:
- J/AJ/144/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on our analysis of Hubble Space Telescope/NICMOS snapshot high-resolution images of 255 stars in 201 systems within ~10 pc of the Sun. Photometry was obtained through filters F110W, F180M, F207M, and F222M using NICMOS Camera 2. These filters were selected to permit clear identification of cool brown dwarfs through methane contrast imaging. With a plate scale of 76mas/pixel, NICMOS can easily resolve binaries with subarcsecond separations in the 19.5"x19".5 field of view. We previously reported five companions to nearby M and L dwarfs from this search. No new companions were discovered during the second phase of data analysis presented here, confirming that stellar/substellar binaries are rare. We establish magnitude and separation limits for which companions can be ruled out for each star in the sample, and then perform a comprehensive sensitivity and completeness analysis for the subsample of 138 M dwarfs in 126 systems. We calculate a multiplicity fraction of 0.0^+3.5^_-0.0_% for L companions to M dwarfs in the separation range of 5-70 AU, and 2.3^+5.0^_-0.7_% for L and T companions to M dwarfs in the separation range of 10-70AU. We also discuss trends in the color-magnitude diagrams using various color combinations and present astrometry for 19 multiple systems in our sample. Considering these results and results from several other studies, we argue that the so-called brown dwarf desert extends to binary systems with low-mass primaries and is largely independent of primary mass, mass ratio, and separations. While focusing on companion properties, we discuss how the qualitative agreement between observed companion mass functions and initial mass functions suggests that the paucity of brown dwarfs in either population may be due to a common cause and not due to binary formation mechanisms.
