- ID:
- ivo://CDS.VizieR/J/A+A/470/231
- Title:
- JHKsIL' images of IRAS 06468-0325
- Short Name:
- J/A+A/470/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our new near-infrared J and Ks-band images taken towards IRAS 06468-0325 revealed the presence of extended emission with very unusual and enigmatic morphology: that of a diamond-ring, that is, a ring or torus with a bright source overlaping the edge of it (not inside it). We report the discovery of this source, explore its nature, and propose possible interpretations of its morphological structure. We observed IRAS 06468-0325 obtaining optical and infrared images through IJHKs and L' filters, K-band low-resolution spectroscopy, together with millimetre line observations of CO(1-0), ^13^CO(2-1), C^18^O(2-1), and CS(2-1).
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/459/669
- Title:
- JHKs photometry around {alpha} Cen
- Short Name:
- J/A+A/459/669
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- alpha Centauri is our closest stellar neighbor, at a distance of only 1.3pc, and its two main components have spectral types comparable to the Sun. This is therefore a favorable target for an imaging search for extrasolar planets. Moreover, indications exist that the gravitational mass of alpha Cen B is higher than its modeled mass, the difference being consistent with a substellar companion of a few tens of Jupiter masses. We searched for faint comoving companions to alpha Cen B. As a secondary objective, we built a catalogue of the detected background sources. We used the NACO adaptive optics system of the VLT in the J, H, and Ks bands to search for companions to alpha Cen B. This instrument allowed us to achieve a very high sensitivity to point-like sources, with a limiting magnitude of m_Ks~18 at 7" from the star. We complemented this data set with archival coronagraphic images from the HST-ACS instrument to obtain an accurate astrometric calibration.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A110
- Title:
- K band spectrum of beta Pictoris b
- Short Name:
- J/A+A/633/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Beta Pictoris is arguably one of the most studied stellar systems outside of our own. Some 30 years of observations have revealed a highly-structured circumstellar disk, with rings, belts, and a giant planet: beta Pictoris b. However very little is known about how this system came into being. Our objective is to estimate the C/O ratio in the atmosphere of {beta} Pictoris b and obtain an estimate of the dynamical mass of the planet, as well as to refine its orbital parameters using high-precision astrometry. We used the GRAVITY instrument with the four 8.2m telescopes of the Very Large Telescope Interferometer to obtain K-band spectro-interferometric data on {beta} Pic b. We extracted a medium resolution (R=500) K-band spectrum of the planet and a high- precision astrometric position. We estimated the planetary C/O ratio using two different approaches (forward modeling and free retrieval) from two different codes (ExoREM and petitRADTRANS, respectively). Finally, we used a simplified model of two formation scenarios (gravitational collapse and core-accretion) to determine which can best explain the measured C/O ratio. Our new astrometry disfavors a circular orbit for beta Pic b (e=0.15^+0.05^_-0.04_). Combined with previous results and with Hipparcos/GAIA measurements, this astrometry points to a planet mass of M=12.7+/-2.2M_{Jup}_. This value is compatible with the mass derived with the free-retrieval code petitRADTRANS using spectral data only. The forward modeling and free-retrieval approches yield very similar results regarding the atmosphere of beta Pic b. In particular, the C/O ratios derived with the two codes are identical (0.43+/-0.05 vs $0.43^+0.04^_-0.03_). We argue that if the stellar C/O in beta Pic is Solar, then this combination of a very high mass and a low C/O ratio for the planet suggests a formation through core-accretion, with strong planetesimal enrichment.
- ID:
- ivo://CDS.VizieR/J/PASP/128/L4401
- Title:
- K2 Campaign 9 added events
- Short Name:
- J/PASP/128/L4401
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K2's Campaign 9 (K2C9) will conduct a ~3.7 deg^2^ survey toward the Galactic bulge from 2016 April 22 through July 2 that will leverage the spatial separation between K2 and the Earth to facilitate measurement of the microlens parallax {pi}_E_ for >~170 microlensing events. These will include several that are planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). These satellite parallax measurements will in turn allow for the direct measurement of the masses of and distances to the lensing systems. In this article we provide an overview of the K2C9 space- and ground-based microlensing survey. Specifically, we detail the demographic questions that can be addressed by this program, including the frequency of FFPs and the Galactic distribution of exoplanets, the observational parameters of K2C9, and the array of resources dedicated to concurrent observations. Finally, we outline the avenues through which the larger community can become involved, and generally encourage participation in K2C9, which constitutes an important pathfinding mission and community exercise in anticipation of WFIRST.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/2634
- Title:
- Kepler and K2 best candidates for planets
- Short Name:
- J/MNRAS/465/2634
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A crucial step in planet hunting surveys is to select the best candidates for follow-up observations, given limited telescope resources. This is often performed by human 'eyeballing', a time consuming and statistically awkward process. Here, we present a new, fast machine learning technique to separate true planet signals from astrophysical false positives. We use self-organizing maps (SOMs) to study the transit shapes of Kepler and K2 known and candidate planets. We find that SOMs are capable of distinguishing known planets from known false positives with a success rate of 87.0 per cent, using the transit shape alone. Furthermore, they do not require any candidate to be dispositioned prior to use, meaning that they can be used early in a mission's lifetime. A method for classifying candidates using a SOM is developed, and applied to previously unclassified members of the Kepler Objects of Interest (KOI) list as well as candidates from the K2 mission. The method is extremely fast, taking minutes to run the entire KOI list on a typical laptop. We make PYTHON code for performing classifications publicly available, using either new SOMs or those created in this work. The SOM technique represents a novel method for ranking planetary candidate lists, and can be used both alone or as part of a larger autovetting code.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A29
- Title:
- Kepler-278 and Kepler-391 spectra
- Short Name:
- J/A+A/634/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kepler-278 and Kepler-391 are two of the three evolved stars on the red giant branch (RGB) known to date, to host multiple short-period transiting planets. Moreover, these planets are among the smallest discovered around RGB stars. Here, we present a detailed stellar and planetary characterization of these remarkable systems. Methods. Based on high-quality spectra from Gemini-GRACES of Kepler-278 and Kepler-391, we obtained refined stellar parameters and precise chemical abundances of 25 elements. Nine of these elements and the carbon isotopic ratios, ^12^C/^13^C, were not previously measured. Also, combining our new stellar parameters with a photodynamical analysis of the Kepler light curves, we determined accurate planetary properties of both systems. Results. Our revised stellar parameters agree reasonably well with most of the previous results, although we find that Kepler-278 is ~15% less massive than previously reported. The abundances of C, N, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, and Ce, in both stars, are consistent with those of evolved nearby thin disk stars. Kepler-391 presents a relatively high abundance of lithium (A(Li)NLTE=1.29+/-0.09dex), which is likely a remnant from the main-sequence phase. The precise spectroscopic parameters of Kepler-278 and Kepler-391 along with their high 12 C/13 C ratios show that both stars are just starting their ascent on the RGB. The planets Kepler-278b, Kepler-278c, and Kepler-391c are warm sub-Neptunes, whilst Kepler-391b is a hot sub-Neptune that falls in the Hot Super-Earth desert and therefore it might be undergoing photo-evaporation of its outer envelope. The high-precision obtained in the transit times allowed us not only to confirm Kepler-278c's TTV signal but also to find evidence of a previously undetected TTV signal for the inner planet Kepler-278b. From the presence of gravitational interaction between these bodies we constrain, for the first time, the mass of Kepler-278b (Mp=56M_Earth_) and Kepler-278c (Mp=35M_Earth_). The mass limits, coupled with our precise determinations of the planetary radii, suggest that their bulk compositions are consistent with a significant amount of water content and the presence of H2 gaseous envelopes. Finally, our photodynamical analysis also shows that the orbits of both planets around Kepler-278 are highly eccentric (e~0.7) and, surprisingly, coplanar. Further observations (e.g., precise radial velocities) of this system are needed to confirm the eccentricity values presented here.
- ID:
- ivo://CDS.VizieR/J/MNRAS/412/1210
- Title:
- Kepler asteroseismic targets
- Short Name:
- J/MNRAS/412/1210
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar structure and evolution can be studied in great detail by asteroseismic methods, provided data of high precision are available. We determine the effective temperature (Teff), surface gravity (logg), metallicity, and the projected rotational velocity (vsini) of 44 Kepler asteroseismic targets using our high-resolution (R>20000) spectroscopic observations; these parameters will then be used to compute asteroseismic models of these stars and to interpret the Kepler light curves.We use the method of cross correlation to measure the radial velocity (RV) of our targets, while atmospheric parameters are derived using the ROTFIT code and spectral synthesis method.
- ID:
- ivo://CDS.VizieR/J/MNRAS/456/2636
- Title:
- Kepler-10 chemical composition
- Short Name:
- J/MNRAS/456/2636
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundance studies of the Sun and solar twins have demonstrated that the solar composition of refractory elements is depleted when compared to volatile elements, which could be due to the formation of terrestrial planets. In order to further examine this scenario, we conducted a line-by-line differential chemical abundance analysis of the terrestrial planet host Kepler-10 and 14 of its stellar twins. Stellar parameters and elemental abundances of Kepler-10 and its stellar twins were obtained with very high precision using a strictly differential analysis of high quality Canada-France-Hawaii Telescope, Hobby-Eberly Telescope and Magellan spectra. When compared to the majority of thick disc twins, Kepler-10 shows a depletion in the refractory elements relative to the volatile elements, which could be due to the formation of terrestrial planets in the Kepler-10 system. The average abundance pattern corresponds to ~13 Earth masses, while the two known planets in Kepler-10 system have a combined ~20 Earth masses. For two of the eight thick disc twins, however, no depletion patterns are found. Although our results demonstrate that several factors [e.g. planet signature, stellar age, stellar birth location and Galactic chemical evolution (GCE)] could lead to or affect abundance trends with condensation temperature, we find that the trends give further support for the planetary signature hypothesis.
- ID:
- ivo://CDS.VizieR/J/MNRAS/409/1470
- Title:
- Kepler compact pulsator candidates
- Short Name:
- J/MNRAS/409/1470
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the first two quarters of a survey to search for pulsations in compact stellar objects with the Kepler spacecraft. The survey sample and the various methods applied in its compilation are described, and spectroscopic observations are presented to separate the objects into accurate classes. From the Kepler photometry we clearly identify nine compact pulsators and a number of interesting binary stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/946
- Title:
- Kepler eclipse timing variation analyses
- Short Name:
- J/MNRAS/448/946
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report eclipse timing variation analyses of 26 compact hierarchical triple stars comprised of an eccentric eclipsing ("inner") binary and a relatively close tertiary component found in the Kepler field. We simultaneously fit the primary and secondary O-C curves of each system for the light-traveltime effect (LTTE), as well as dynamical perturbations caused by the tertiary on different time-scales. For the first time, we include those contributions of three-body interactions which originate from the eccentric nature of the inner binary. These effects manifest themselves both on the period of the triple system, P_2_, and on the longer "apse-node" time-scale. We demonstrate that consideration of the dynamically forced rapid apsidal motion yields an efficient and independent tool for the determination of the binary orbit's eccentricity and orientation, as well as the 3D configuration of the triple. Modelling the forced apsidal motion also helps to resolve the degeneracy between the shapes of the LTTE and the dynamical delay terms on the P_2_ time-scale, due to the strong dependence of the apsidal motion period on the triple's mass ratio. This can lead to the independent determination of the binary and tertiary masses without the need for independent radial velocity measurements. Through the use of our analytic method for fitting O-C curves, we have obtained robust solutions for system parameters for the 10 most ideal triples of our sample, and only somewhat less robust, but yet acceptable, fits for the remaining systems. Finally, we study the results of our 26 system parameter fits via a set of distributions of various physically important parameters, including mutual inclination angle, and mass and period ratios.
