- ID:
- ivo://CDS.VizieR/J/ApJ/654/625
- Title:
- Radial velocities of 9 long-period objects
- Short Name:
- J/ApJ/654/625
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The possible existence of additional long-period planetary-mass objects in the extrasolar planetary systems 47 UMa and 14 Her is investigated. We combine all available radial velocity data on these stars, spanning up to 18yr. For the 47 UMa system, we show that while a second planet improves the fit to all available data, there is still substantial ambiguity as to the orbital parameters of the proposed planetary companion 47 UMa c. We also present new observations that clearly support a long-period companion in the 14 Her system. With a period of 6906+/-70 days, 14 Her c may be in a 4:1 resonance with the inner planet. We also present revised orbital solutions for seven previously known planets, incorporating recent additional data obtained with the 2.7m Harlan J. Smith Telescope at McDonald Observatory.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/800/22
- Title:
- Radial velocities of long-period planets
- Short Name:
- J/ApJ/800/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an update to seven stars with long-period planets or planetary candidates using new and archival radial velocities from Keck-HIRES and literature velocities from other telescopes. Our updated analysis better constrains orbital parameters for these planets, four of which are known multi-planet systems. HD24040b and HD183263c are super-Jupiters with circular orbits and periods longer than 8yr. We present a previously unseen linear trend in the residuals of HD 66428 indicative of an additional planetary companion. We confirm that GJ 849 is a multi-planet system and find a good orbital solution for the c component: it is a 1M_Jup_ planet in a 15yr orbit (the longest known for a planet orbiting an M dwarf). We update the HD74156 double-planet system. We also announce the detection of HD145934b, a 2M_Jup_ planet in a 7.5yr orbit around a giant star. Two of our stars, HD187123 and HD217107, at present host the only known examples of systems comprising a hot Jupiter and a planet with a well constrained period greater than 5yr, and with no evidence of giant planets in between. Our enlargement and improvement of long-period planet parameters will aid future analysis of origins, diversity, and evolution of planetary systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/730/67
- Title:
- Radial velocities of low-mass white dwarfs
- Short Name:
- J/ApJ/730/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe spectroscopic observations of 21 low-mass (<=0.45M_{sun}_) white dwarfs (WDs) from the Palomar-Green survey obtained over four years. We use both radial velocities and infrared photometry to identify binary systems, and find that the fraction of single, low-mass WDs is <=30%. We discuss the potential formation channels for these single stars including binary mergers of lower-mass objects. However, binary mergers are not likely to explain the observed number of single low-mass WDs. Thus, additional formation channels, such as enhanced mass loss due to winds or interactions with substellar companions, are likely.
- ID:
- ivo://CDS.VizieR/J/ApJ/698/514
- Title:
- Radial velocities of LSI+61 303 and LS 5039
- Short Name:
- J/ApJ/698/514
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- LS I +61 303 and LS 5039 are two of only a handful of known high-mass X-ray binaries (HMXBs) that exhibit very high energy emission in the MeV-TeV range, and these "{gamma}-ray binaries" are of renewed interest due to the recent launch of the Fermi Gamma-ray Space Telescope. Here we present new radial velocities of both systems based on recent red and blue optical spectra. Both systems have somewhat discrepant orbital solutions available in the literature, and our new measurements result in improved orbital elements and resolve the disagreements. The improved geometry of each orbit will aid in studies of the high-energy emission region near each source.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A14
- Title:
- Radial velocities of magnetic Ap stars
- Short Name:
- J/A+A/601/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Some Ap stars that have a strong enough magnetic field and a sufficiently low v sin i show spectral lines resolved into their magnetically split components. We present the results of a systematic study of the magnetic fields and other properties of those stars. Methods. This study is based on 271 new measurements of the mean magnetic field modulus <B> of 43 stars, 231 determinations of the mean longitudinal magnetic field <Bz> and of the crossover <Xz> of 34 stars, and 229 determinations of the mean quadratic magnetic field <Bq> of 33 stars. Those data were used to derive new values or meaningful lower limits of the rotation periods Prot of 21 stars. Variation curves of the mean field modulus were characterised for 25 stars, the variations of the longitudinal field were characterised for 16 stars, and the variations of the crossover and of the quadratic field were characterised for 8 stars. Our data are complemented by magnetic measurements from the literature for 41 additional stars with magnetically resolved lines. Phase coverage is sufficient to define the curve of variation of Hm for 2 of these stars. Published data were also used to characterise the Hz curves of variation for 10 more stars. Furthermore, we present 1297 radial velocity measurements of the 43 Ap stars in our sample that have magnetically resolved lines. Nine of these stars are spectroscopic binaries for which new orbital elements were derived. The existence of a cut-off at the low end of the distribution of the phase-averaged mean magnetic field moduli <B>av of the Ap stars with resolved magnetically split lines, at about 2.8kG, is confirmed. This reflects the probable existence of a gap in the distribution of the magnetic field strengths in slowly rotating Ap stars, below which there is a separate population of stars with fields weaker than ~2kG. In more than half of the stars with magnetically resolved lines that have a rotation period shorter than 150 days, <B>av>7.5kG, while those stars with a longer period all have <B>av<7.5kG. The difference between the two groups is significant at the 100.0% confidence level. The relative amplitudes of variation of the mean field modulus may tend to be greater in stars with Prot>100d than in shorter period stars. The root-mean-square longitudinal fields of all the studied stars but one is less than one-third of their phase-averaged mean field moduli, which is consistent with the expected behaviour for fields whose geometrical structure resembles a centred dipole. However, moderate but significant departures from the latter are frequent. Crossover resulting from the correlation between the Zeeman effect and the rotation-induced Doppler effect across the stellar surface is definitely detected in stars with rotation periods of up to 130 days and possibly even up to 500 days. Weak, but formally significant crossover of constant sign, has also been observed in a number of longer period stars, which could potentially be caused by pulsation velocity gradients across the depth of the photosphere. The quadratic field is in average ~1.3 times greater than the mean field modulus and both of those moments vary with similar relative amplitudes and almost in phase in most stars. Rare exceptions almost certainly have unusual field structures. The distribution of the known values and lower limits of the rotation periods of the Ap stars with magnetically resolved lines indicates that for some of them, Prot must almost certainly reach 300 years or possibly even much higher values. Of the 43 Ap stars that we studied in detail, 22 are in binary systems. The shortest orbital period P_orb of those systems is 27 days. For those non-synchronised Ap binaries for which both the rotation period and the orbital period, or meaningful lower limits thereof, are reliably determined, the distribution of the orbital periods of the systems in which the Ap star has a rotation period that is shorter than 50 days is different from its distribution for those systems in which the rotation period of the Ap star is longer, at a confidence level of 99.6%. The shortest rotation and orbital periods are mutually exclusive: all but one of the non-synchronised systems that contain an Ap component with Prot<50d, have Porb>1000d. Stars with resolved magnetically split lines represent a significant fraction, of the order of several percent, of the whole population of Ap stars. Most of these stars are genuine slow rotators, whose consideration provides new insight into the long-period tail of the distribution of the periods of Ap stars. Emerging correlations between rotation periods and magnetic properties provide important clues for the understanding of the braking mechanisms that have been at play in the early stages of stellar evolution. The geometrical structures of the magnetic fields of Ap stars with magnetically resolved lines appear in general to depart slightly, but not extremely, from centred dipoles. However, there are a few remarkable exceptions, which deserve further consideration. Confirmation that pulsational crossover is indeed occurring at a detectable level would open the door to the study of non-radial pulsation modes of degree l, which is too high for photometric or spectroscopic observations. How the lack of short orbital periods among binaries containing an Ap component with magnetically resolved lines is related to their (extremely) slow rotation remains to be fully understood, but the very existence of a correlation between the two periods lends support to the merger scenario for the origin of Ap stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/751/4
- Title:
- Radial velocities of massive stars in Cyg OB2
- Short Name:
- J/ApJ/751/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work provides a statistical analysis of the massive star binary characteristics in the Cygnus OB2 association using radial velocity information of 114 B3-O5 primary stars and orbital properties for the 24 known binaries. We compare these data to a series of Monte Carlo simulations to infer the intrinsic binary fraction and distributions of mass ratios, periods, and eccentricities. We model the distribution of mass ratio, log-period, and eccentricity as power laws and find best-fitting indices of {alpha}=0.1+/-0.5, {beta}=0.2+/-0.4, and {gamma}=-0.6+/-0.3, respectively. These distributions indicate a preference for massive companions, short periods, and low eccentricities. Our analysis indicates that the binary fraction of the cluster is 44%+/-8% if all binary systems are (artificially) assumed to have P<1000 days; if the power-law period distribution is extrapolated to 10^4^ years, then a plausible upper limit for bound systems, the binary fraction is ~90%+/-10%. Of these binary (or higher order) systems, ~45% will have companions close enough to interact during pre- or post-main-sequence evolution (semi-major axis <~4.7AU). The period distribution for P<26 days is not well reproduced by any single power law owing to an excess of systems with periods around 3-5 days (0.08-0.31AU) and a relative shortage of systems with periods around 7-14 days (0.14-0.62AU). We explore the idea that these longer-period systems evolved to produce the observed excess of short-period systems. The best-fitting binary parameters imply that secondaries generate, on average, ~16% of the V-band light in young massive populations. This means that photometrically based distance measurements for young massive clusters and associations will be systematically low by ~8% (0.16 mag in the distance modulus) if the luminous contributions of unresolved secondaries are not taken into account.
- ID:
- ivo://CDS.VizieR/J/A+A/456/985
- Title:
- Radial velocities of 76 M31 candidate clusters
- Short Name:
- J/A+A/456/985
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a large spectroscopic survey of globular clusters and candidate globular clusters in the nearby M31 galaxy. The survey is aimed at the classification of known candidate M31 clusters and at the study of their kinematic properties. We obtained low-resolution spectroscopy for 133 targets, including 76 yet-to-be-confirmed candidate clusters (i.e. with no previous spectroscopic information), 55 already-confirmed genuine M31 clusters, and 2 uncertain candidates. Our observations allowed a reliable estimate of the target radial velocity, within a typical accuracy of ~+/-20Km/s. The observed candidates have been robustly classified according to their radial velocity and shape parameters that allowed us to confidently discriminate between point sources and extended objects even from low-spatial-resolution imagery. In our set of 76 candidate clusters we found: 42 newly-confirmed bona-fide M31 clusters, 12 background galaxies, 17 foreground Galactic stars, 2 HII regions belonging to M31 and 3 unclassified (possibly M31 clusters or foreground stars) objects. The classification of a few other candidates not included in our survey has been also reassessed on various observational bases. All the sources of radial velocity estimates for M31 known globular clusters available in the literature have been compared and checked, and a homogeneous general list has been obtained for 349 confirmed clusters with radial velocity. Our results suggest that a significant number of genuine clusters (~>100) is still hidden among the plethora of known candidates proposed by various authors. Hence our knowledge of the globular cluster system of the M31 galaxy is still far from complete even in terms of simple membership.
- ID:
- ivo://CDS.VizieR/J/AJ/160/3
- Title:
- Radial velocities of M-dwarf LTT 3780 with HARPS
- Short Name:
- J/AJ/160/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the confirmation of two new planets transiting the nearby mid-M dwarf LTT3780 (TIC36724087, TOI-732, V=13.07, Ks=8.204, Rs=0.374R{sun}, Ms=0.401 M{sun}, d=22pc). The two planet candidates are identified in a single Transiting Exoplanet Survey Satellite sector and validated with reconnaissance spectroscopy, ground-based photometric follow-up, and high-resolution imaging. With measured orbital periods of P_b_=0.77, P_c_=12.25days and sizes r_p,b_=1.33{+/-}0.07, r_p,c_=2.30{+/-}0.16R{earth}, the two planets span the radius valley in period-radius space around low-mass stars, thus making the system a laboratory to test competing theories of the emergence of the radius valley in that stellar mass regime. By combining 63 precise radial velocity measurements from the High Accuracy Radial velocity Planet Searcher (HARPS) and HARPS-N, we measure planet masses of m_p,b_=2.62_-0.46_^+0.48^ and m_p,c_=8.6_-1.3_^+1.6^M{earth}, which indicates that LTT3780b has a bulk composition consistent with being Earth-like, while LTT3780c likely hosts an extended H/He envelope. We show that the recovered planetary masses are consistent with predictions from both photoevaporation and core-powered mass-loss models. The brightness and small size of LTT3780, along with the measured planetary parameters, render LTT3780b and c as accessible targets for atmospheric characterization of planets within the same planetary system and spanning the radius valley.
- ID:
- ivo://CDS.VizieR/J/AJ/135/196
- Title:
- Radial velocities of 45 metal-poor field stars
- Short Name:
- J/AJ/135/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 349 radial velocities for 45 metal-poor field red giant branch (RGB) and red horizontal branch (RHB) stars, with time coverage ranging from 1 to 21 years. We have identified one new spectroscopic binary, HD 4306, and one possible such system, HD 184711. We also provide 57 radial velocities for 11 of the 91 stars reported in our previous work. All but one of the 11 stars had been found to have variable radial velocities.
- ID:
- ivo://CDS.VizieR/J/ApJ/591/850
- Title:
- Radial velocities of M49 globular clusters
- Short Name:
- J/ApJ/591/850
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Low Resolution Imaging Spectrometer on the Keck I and II telescopes, we have measured radial velocities for 196 globular clusters (GCs) around M49 (NGC 4472), the brightest member of the Virgo Cluster. Combined with published data, they bring the total number of GCs with measured radial velocities in this galaxy to 263. In terms of sample size, spatial coverage, velocity precision, and the availability of metallicity estimates from Washington photometry, this radial velocity database resembles that presented recently for M87 (NGC 4486), Virgo's cD galaxy and its second-ranked member. We extract the projected kinematics of the full sample of GCs and of separate subsamples of 158 metal-poor and 105 metal-rich GCs.
