- ID:
- ivo://CDS.VizieR/J/ApJ/876/23
- Title:
- Multiple populations of extrasolar gas giants
- Short Name:
- J/ApJ/876/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There are two planetary formation scenarios: core accretion and gravitational disk instability. Based on the fact that gaseous objects are preferentially observed around metal-rich host stars, most extrasolar gaseous objects discovered to date are thought to have been formed by core accretion. Here, we present 569 samples of gaseous planets and brown dwarfs found in 485 planetary systems that span three mass regimes with boundary values at 4 and 25 Jupiter-mass masses through performing cluster analyses of these samples regarding the host-star metallicity, after minimizing the impact of the selection effect of radial-velocity measurement on the cluster analysis. The larger mass is thought to be the upper mass limit of the objects that were formed during the planetary formation processes. In contrast, the lower mass limit appears to reflect the difference between planetary formation processes around early-type and G-type stars; disk instability plays a greater role in the planetary formation process around early-type stars than that around G-type stars. Populations with masses between 4 and 25 Jupiter masses that orbit early-type stars comprise planets formed not only via the core-accretion process but also via gravitational disk instability because the population preferentially orbits metal-poor stars or is independent of the host-star metallicity. Therefore, it is essential to have a hybrid scenario for the planetary formation of the diverse systems.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/813/83
- Title:
- Multiple star formation in Ophiuchus
- Short Name:
- J/ApJ/813/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conduct a multiplicity survey of members of the {rho} Ophiuchus cloud complex with high-resolution imaging to characterize the multiple-star population of this nearby star-forming region and investigate the relation between stellar multiplicity and star and planet formation. Our aperture masking survey reveals the presence of five new stellar companions beyond the reach of previous studies, but does not result in the detection of any new substellar companions. We find that 43+/-6% of the 114 stars in our survey have stellar-mass companions between 1.3 and 780 AU, while 7_-5_^+8^% host brown dwarf companions in the same interval. By combining this information with knowledge of disk-hosting stars, we show that the presence of a close binary companion (separation <40AU) significantly influences the lifetime of protoplanetary disks, a phenomenon previously seen in older star-forming regions. At the ~1-2Myr age of our Ophiuchus members ~2/3 of close binary systems have lost their disks, compared to only ~30% of single stars and wide binaries. This has a significant impact on the formation of giant planets, which are expected to require much longer than 1 Myr to form via core accretion and thus planets formed via this pathway should be rare in close binary systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/731/8
- Title:
- Multiple star formation in Taurus-Auriga
- Short Name:
- J/ApJ/731/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a high-resolution imaging study of the Taurus-Auriga star-forming region in order to characterize the primordial outcome of multiple star formation and the extent of the brown dwarf desert. Our survey identified 16 new binary companions to primary stars with masses of 0.25-2.5M_{sun}_, raising the total number of binary pairs (including components of high-order multiples) with separations of 3-5000AU to 90. We find that ~2/3-3/4 of all Taurus members are multiple systems of two or more stars, while the other ~1/4-1/3 appear to have formed as single stars; the distribution of high-order multiplicity suggests that fragmentation into a wide binary has no impact on the subsequent probability that either component will fragment again. The separation distribution for solar-type stars (0.7-2.5M_{sun}_) is nearly log-flat over separations of 3-5000AU, but lower-mass stars (0.25-0.7M_{sun}_) show a paucity of binary companions with separations of >~200AU. Across this full mass range, companion masses are well described with a linear-flat function; all system mass ratios (q=M_B_/M_A_) are equally probable, apparently including substellar companions. Our results are broadly consistent with the two expected modes of binary formation (free-fall fragmentation on large scales and disk fragmentation on small scales), but the distributions provide some clues as to the epochs at which the companions are likely to form.
- ID:
- ivo://CDS.VizieR/J/AJ/155/160
- Title:
- Multiple systems:relative positions and residuals
- Short Name:
- J/AJ/155/160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper draws attention to the class of resolved triple stars with moderate ratios of inner and outer periods (possibly in a mean motion resonance) and nearly circular, mutually aligned orbits. Moreover, stars in the inner pair are twins with almost identical masses, while the mass sum of the inner pair is comparable to the mass of the outer component. Such systems could be formed either sequentially (inside-out) by disk fragmentation with subsequent accretion and migration, or by a cascade hierarchical fragmentation of a rotating cloud. Orbits of the outer and inner subsystems are computed or updated in four such hierarchies: LHS 1070 (GJ 2005, periods 77.6 and 17.25 years), HIP 9497 (80 and 14.4 years), HIP 25240 (1200 and 47.0 years), and HIP 78842 (131 and 10.5 years).
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/85
- Title:
- Multi-wavelength analysis of the MIR bubble N37
- Short Name:
- J/ApJ/833/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a multi-wavelength analysis of a mid-infrared (MIR) bubble N37 and its surrounding environment. The selected 15'x15' area around the bubble contains two molecular clouds (N37 cloud; V_lsr_~37-43km/s, and C25.29+0.31; V_lsr_~43-48km/s) along the line of sight. A total of seven OB stars are identified toward the bubble N37 using photometric criteria, and two of them are spectroscopically confirmed as O9V and B0V stars. The spectro-photometric distances of these two sources confirm their physical association with the bubble. The O9V star appears to be the primary ionizing source of the region, which is also in agreement with the desired Lyman continuum flux analysis estimated from the 20cm data. The presence of the expanding HII region is revealed in the N37 cloud, which could be responsible for the MIR bubble. Using the ^13^CO line data and photometric data, several cold molecular condensations as well as clusters of young stellar objects (YSOs) are identified in the N37 cloud, revealing ongoing star formation (SF) activities. However, the analysis of ages of YSOs and the dynamical age of the HII region do not support the origin of SF due to the influence of OB stars. The position-velocity analysis of ^13^CO data reveals that two molecular clouds are interconnected by a bridge-like structure, favoring the onset of a cloud-cloud collision process. The SF activities (i.e., the formation of YSO clusters and OB stars) in the N37 cloud are possibly influenced by the cloud-cloud collision.
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/2502
- Title:
- Multiwavelength study of HII region S311
- Short Name:
- J/MNRAS/461/2502
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multiwavelength investigation of the young stellar population and star formation activities around the HII region Sharpless 311. Using our deep near-infrared observations and archival Spitzer-IRAC observations, we have detected a total of 125 young stellar objects (YSOs) in an area of ~86 arcmin^2^. The YSO sample includes eight Class I and 117 Class II candidate YSOs. The mass completeness of the identified YSO sample is estimated to be 1.0M_{sun}_. The ages and masses of the majority of the candidate YSOs are estimated to be in the range ~0.1-5Myr and ~0.3-6M_{sun}_, respectively. The 8um image of S311 displays an approximately spherical cavity around the ionizing source, which was possibly created by the expansion of the H ii region. The spatial distribution of the candidate YSOs reveals that a significant number of them are distributed systematically along the 8-{mu}m emission with a majority clustered around the eastern border of the HII region. Four clumps/compact HII regions are detected in the radio continuum observations at 1280MHz, which may have been formed during the expansion of the HII region. The estimated dynamical age of the region, main-sequence lifetime of the ionizing source, the spatial distribution and ages of the candidate YSOs indicate triggered star formation in the complex.
- ID:
- ivo://CDS.VizieR/J/ApJ/791/54
- Title:
- Nearby M Dwarfs parameters
- Short Name:
- J/ApJ/791/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Comparisons between the planet populations around solar-type stars and those orbiting M dwarfs shed light on the possible dependence of planet formation and evolution on stellar mass. However, such analyses must control for other factors, i.e., metallicity, a stellar parameter that strongly influences the occurrence of gas giant planets. We obtained infrared spectra of 121 M dwarfs stars monitored by the California Planet Search and determined metallicities with an accuracy of 0.08 dex. The mean and standard deviation of the sample are -0.05 and 0.20 dex, respectively. We parameterized the metallicity dependence of the occurrence of giant planets on orbits with a period less than two years around solar-type stars and applied this to our M dwarf sample to estimate the expected number of giant planets. The number of detected planets (3) is lower than the predicted number (6.4), but the difference is not very significant (12% probability of finding as many or fewer planets). The three M dwarf planet hosts are not especially metal rich and the most likely value of the power-law index relating planet occurrence to metallicity is 1.06 dex per dex for M dwarfs compared to 1.80 for solar-type stars; this difference, however, is comparable to uncertainties. Giant planet occurrence around both types of stars allows, but does not necessarily require, a mass dependence of ~1 dex per dex. The actual planet-mass-metallicity relation may be complex, and elucidating it will require larger surveys like those to be conducted by ground-based infrared spectrographs and the Gaia space astrometry mission.
- ID:
- ivo://CDS.VizieR/V/101
- Title:
- Nearest stars until 10pc
- Short Name:
- V/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The given catalogue is a revised version of the catalogue (Zakhozhaj, 1987). The previous numeration is preserved, and the stars, with trigonometric, photometric and spectral parallaxes >0.100" are presented. The catalogue contains data on new components of multiple visual systems, on the components of spectral-binary systems, on invisible components with masses >0.08 solar mass. New data are obtained in 90s and contained in the articles [2-6]. The catalogue contains the main characteristics of stars such as the positions, proper motions, radial velocities, parallaxes, photometrical data and also new data of masses and radii of stars. The completeness of the catalogue is about 70%.
- ID:
- ivo://CDS.VizieR/J/AJ/144/7
- Title:
- Near-IR imaging of Hipparcos astrometric binaries
- Short Name:
- J/AJ/144/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A subset of 51 Hipparcos astrometric binaries among FG dwarfs within 67pc has been surveyed with the Near-Infrared Coronagraphic Imager adaptive optics system at Gemini-S, directly resolving for the first time 17 subarcsecond companions and 7 wider ones. Using these data together with published speckle interferometry of 57 stars, we compare the statistics of resolved astrometric companions with those of a simulated binary population. The fraction of resolved companions is slightly lower than expected from binary statistics. About 10% of astrometric companions could be "dark" (white dwarfs and close pairs of late M-dwarfs). To our surprise, several binaries are found with companions too wide to explain the acceleration. Re-analysis of selected intermediate astrometric data shows that some acceleration solutions in the original Hipparcos catalog are spurious.
