- ID:
- ivo://CDS.VizieR/J/MNRAS/507/1847
- Title:
- A HARPS-N mass for the elusive Kepler-37d
- Short Name:
- J/MNRAS/507/1847
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To date, only 18 exoplanets with radial velocity (RV) semi-amplitudes <2m/s have had their masses directly constrained. The biggest obstacle to RV detection of such exoplanets is variability intrinsic to stars themselves, e.g. nuisance signals arising from surface magnetic activity such as rotating spots and plages, which can drown out or even mimic planetary RV signals. We use Kepler-37 - known to host three transiting planets, one of which, Kepler-37d, should be on the cusp of RV detectability with modern spectrographs - as a case study in disentangling planetary and stellar activity signals. We show how two different statistical techniques - one seeking to identify activity signals in stellar spectra, and another to model activity signals in extracted RVs and activity indicators - can enable detection of the hitherto elusive Kepler-37d. Moreover, we show that these two approaches can be complementary, and in combination, facilitate a definitive detection and precise characterisation of Kepler-37d. Its RV semi-amplitude of 1.22+/-0.31m/s (mass 5.4+/-1.4M_{Earth}_) is formally consistent with TOI-178b's 1.05^+0.25^_-0.30_m/s, the latter being the smallest detected RV signal of any transiting planet to date, though dynamical simulations suggest Kepler-37d's mass may be on the lower end of our 1{sigma} credible interval. Its consequent density is consistent with either a water-world or that of a gaseous envelope (~0.4% by mass) surrounding a rocky core. Based on RV modelling and a re-analysis of Kepler-37 TTVs, we also argue that the putative (non-transiting) planet Kepler-37e should probably be stripped of its 'confirmed' status.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/594/A54
- Title:
- A 1689 HAWK-I J-band image
- Short Name:
- J/A+A/594/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a ground-based, near-infrared search for lensed supernovae behind the massive cluster Abell 1689 at z=0.18, which is one of the most powerful gravitational telescopes that nature provides. Our survey was based on multi-epoch J-band observations with the HAWK-I instrument on VLT, with supporting optical data from the Nordic Optical Telescope. Our search resulted in the discovery of five photometrically classified, core-collapse supernovae with high redshifts of 0.671<z<1.703 and magnifications in the range {DELTA}m=-0.31 to -1.58mag, as calculated from lensing models in the literature. Owing to the power of the lensing cluster, the survey had the sensitivity to detect supernovae up to very high redshifts, z~3, albeit for a limited region of space. We present a study of the core-collapse supernova rates for 0.4<=z<2.9, and find good agreement with previous estimates and predictions from star formation history. During our survey, we also discovered two Type Ia supernovae in A 1689 cluster members, which allowed us to determine the cluster Ia rate to be 0.14+0.19-0.09+/-0.01SNuB*h^2^ (SNuB=10^-12^SNeL_{sun},B_^-1^yr^-1^), where the error bars indicate 1{sigma} confidence intervals, statistical and systematic, respectively. The cluster rate normalized by the stellar mass is 0.10+0.13-0.096+/-0.02 in SNuM*h^2^ (SNuM=10^-12^SNeM_{sun}_^-1^yr^-1^). Furthermore, we explore the optimal future survey for improving the core-collapse supernova rate measurements at z>~2 using gravitational telescopes, and for detections with multiply lensed images, and we find that the planned WFIRST space mission has excellent prospects.
693. AH Cam
- ID:
- ivo://CDS.VizieR/J/AJ/107/679
- Title:
- AH Cam
- Short Name:
- J/AJ/107/679
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Analysis of 746 new V-band observations of the RR Lyrae star AH Cam obtained during 1989-1992 clearly show that its light curve cannot be described by a single period. In fact, at first glance, the Fourier spectrum of the photometry resembles that of a double-mode pulsator, with peaks at a fundamental period of 0.3686d and an apparent secondary period of 0.2628d. Nevertheless, the dual-mode solution is a poor fit to the data. Rather, we believe that AH Cam is a single-mode RR Lyrae star undergoing the Blazhko effect: periodic modulation of the amplitude and shape of its light curve. What was originally taken to be the period of the second mode is instead the 1-cycle/d alias of a modulation sidelobe in the Fourier spectrum. The data are well described by a modulation period of just under 11d, which is the shortest Blazhko period reported to date in the literature and confirms the earlier suggestion by Goranskii. A low-resolution spectrum of AH Cam indicates that it is relatively metal rich, with {DELTA}S<=2. Its high metallicity and short modulation period may provide a critical test of at least one theory for the Blazhko effect. Moskalik's internal resonance model makes specific predictions of the growth rate of the fundamental mode vs fundamental period. AH Cam falls outside the regime of other known Blazhko variables and resonance model predictions, but these are appropriate for metal-poor RR Lyrae stars. If the theory matches the behavior of AH Cam for a metal-rich stellar model, this would bolster the resonance hypothesis.
- ID:
- ivo://CDS.VizieR/J/A+A/367/111
- Title:
- A Hipparcos study of the Hyades cluster
- Short Name:
- J/A+A/367/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hipparcos trigonometric parallaxes fix distances to individual stars in the Hyades cluster with an accuracy of about 6 percent. We use the Hipparcos and Tycho-2 proper motions, which have a larger relative precision than the Hipparcos trigonometric parallaxes, to derive 3 times more precise distance estimates, by assuming that all members share the same space motion. These so-called secular parallaxes are, as a set, statistically consistent with the Hipparcos parallaxes (Section 6). Table A1 contains, for all 218 members identified by Perryman et al. (1998A&A...331...81P; see also Cat. <J/A+A/331/81>; see Sections 4.1 and 5.1), the trigonometric parallaxes, the Hipparcos and Tycho-2 secular parallaxes, their errors and goodness-of-fit parameters (Sections 2.2 and 5.4), as well as fundamental stellar parameters (Section 9) based on the Hipparcos secular parallaxes and the V-band magnitudes (field H5) and B-V colours (field H37) listed in the Hipparcos Catalogue (1997HIP...C......0E; Cat. <I/239>). Table A2 lists 15 new Hyades candidates (see Sections 4.2 and 5.2) selected by the membership methods developed by de Bruijne (1999MNRAS.306..381D) and Hoogerwerf et al. (1999MNRAS.306..394H) which use proper motion and trigonometric parallax data. Based on photometric, radial velocity, and secular parallax data, we conclude that only one of these stars (HIP 19757) is a likely new member (see Sections 4.2 and 5.2 for details).
- ID:
- ivo://CDS.VizieR/J/A+AS/112/347
- Title:
- A Homogeneous Bright QSO Survey
- Short Name:
- J/A+AS/112/347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first paper in a series aimed at defining a statistically significant sample of QSOs in the range 15<B<18.75 and 0.3<z<2.2. The selection is carried out using direct plates obtained at the ESO and UK Schmidt Telescopes, scanned with the COSMOS facility and searched for objects with an ultraviolet excess. Follow-up spectroscopy, carried out at ESO La Silla, is used to classify each candidate. In this initial paper, we describe the scientific objectives of the survey; the selection and observing techniques used. We present the first sample of 285 QSOs (M_B_<-23) in a 153 sq.deg area, covered by the six "deep" fields, intended to obtain significant statistics down B=~18.75 with unprecedented photometric accuracy. From this database, QSO counts are determined in the magnitude range 17<B<18.75.
- ID:
- ivo://CDS.VizieR/J/ApJ/815/33
- Title:
- A Hubble diagram for quasars
- Short Name:
- J/ApJ/815/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new method to test the {Lambda}CDM cosmological model and to estimate cosmological parameters based on the nonlinear relation between the ultraviolet and X-ray luminosities of quasars. We built a data set of 1138 quasars by merging several samples from the literature with X-ray measurements at 2keV and SDSS photometry, which was used to estimate the extinction-corrected 2500{AA} flux. We obtained three main results: (1) we checked the nonlinear relation between X-ray and UV luminosities in small redshift bins up to z~6, confirming that the relation holds at all redshifts with the same slope; (2) we built a Hubble diagram for quasars up to z~6, which is well matched to that of supernovae in the common z=0-1.4 redshift interval and extends the test of the cosmological model up to z~6; and (3) we showed that this nonlinear relation is a powerful tool for estimating cosmological parameters. Using the present data and assuming a {Lambda}CDM model, we obtain {Omega}_M_=0.22_-0.08_^+0.10^ and {Omega}_{Lambda}_=0.92-0.30_^+0.18^ ({Omega}=0.28+/-0.04 and {Omega}_{Lambda}_=0.73+/-0.08 from a joint quasar-SNe fit). Much more precise measurements will be achieved with future surveys. A few thousand SDSS quasars already have serendipitous X-ray observations from Chandra or XMM-Newton, and at least 100000 quasars with UV and X-ray data will be made available by the extended ROentgen Survey with an Imaging Telescope Array all-sky survey in a few years. The Euclid, Large Synoptic Survey Telescope, and Advanced Telescope for High ENergy Astrophysics surveys will further increase the sample size to at least several hundred thousand. Our simulations show that these samples will provide tight constraints on the cosmological parameters and will allow us to test for possible deviations from the standard model with higher precision than is possible today.
- ID:
- ivo://CDS.VizieR/J/PAZh/43/460
- Title:
- AI CMi UBV light curves
- Short Name:
- J/PAZh/43/460
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The U BV photometry and low-resolution spectroscopy for the semiregular variable AI CMi, a candidate for post-AGB objects, performed in 1996-2016 and 2000-2013, respectively, are presented. The star showed multiperiodic brightness variations with an amplitude up to 1.5m in the V band, a significant (up to 0.4m) bluing of the B-V and U-B colors as the star faded, and a change of its spectrum from G5 I to K3-5 I, depending on its brightness. A possible long-term fading of AI CMi below 8.5m in the period from May 2013 to early 2015 is observed in the light curve. The colors in this episode did not change the pattern of their unusual behavior with brightness. The main feature of the spectrum for AI CMi is the appearance and strengthening of TiO absorption bands as its brightness declines, which are atypical in the spectra of ordinary G5-K3 supergiants. The bluing of the B-V and U-B colors is interpreted as the blanketing of stellar radiation predominantly in V (and to a lesser extent in B) by the TiO absorption bands whose intensity increases dramatically with decreasing brightness. Another cause of the bluing can be the scattering of stellar radiation by small dust particles in the gas-dust shell of AI CMi. The star's continuum-normalized spectra over the period from 2000 to 2013 in the wavelength range 4200 to 7700 or 9200{AA} are presented. These were taken at different phases of the pulsation cycle and clearly demonstrate the behavior of the TiO absorption bands depending on the V magnitude and B-V color. The equivalent widths of individual TiO bands were measured, and their correlation with the photometric parameters of the star is shown. AI CMi belongs to the O-rich branch of AGB/post-AGB supergiants and has a luminosity of ~4000L_{sun}_ at a distance of 1500+/-700pc. The mass of AI CMi is most likely small and close to the lower mass limit for post-AGB stars. The connection of the star's pulsational activity and nonstationary wind with the formation of its molecular and dust shells is discussed briefly.
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/1151
- Title:
- AIMSS Project. I. Compact Stellar Systems
- Short Name:
- J/MNRAS/443/1151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the structural and kinematic properties of the first compact stellar systems discovered by the Archive of Intermediate Mass Stellar Systems project. These spectroscopically confirmed objects have sizes (~6<R_e_[pc]<500) and masses (~2x10^6^<M*/M_{sun}_<6x10^9^) spanning the range of massive globular clusters, ultracompact dwarfs (UCDs) and compact elliptical galaxies (cEs), completely filling the gap between star clusters and galaxies. Several objects are close analogues to the prototypical cE, M32. These objects, which are more massive than previously discovered UCDs of the same size, further call into question the existence of a tight mass-size trend for compact stellar systems, while simultaneously strengthening the case for a universal 'zone of avoidance' for dynamically hot stellar systems in the mass-size plane. Overall, we argue that there are two classes of compact stellar systems (1) massive star clusters and (2) a population closely related to galaxies. Our data provide indications for a further division of the galaxy-type UCD/cE population into two groups, one population that we associate with objects formed by the stripping of nucleated dwarf galaxies, and a second population that formed through the stripping of bulged galaxies or are lower mass analogues of classical ellipticals. We find compact stellar systems around galaxies in low- to high-density environments, demonstrating that the physical processes responsible for forming them do not only operate in the densest clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/139/434
- Title:
- A1763 infrared and optical photometry
- Short Name:
- J/AJ/139/434
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric analysis of the galaxy cluster Abell 1763 at visible and infrared wavelengths. Included are fully reduced images in r', J, H, and Ks obtained using the Palomar 200in telescope, as well as the IRAC and MIPS images from Spitzer. The cluster is covered out to approximately 3 virial radii with deep 24um imaging (a 5{sigma} depth of 0.2mJy). This same field of ~40'x40' is covered in all four IRAC bands as well as the longer wavelength MIPS bands (70 and 160um). The r' imaging covers ~0.8deg^2^ down to 25.5mag, and overlaps with most of the MIPS field of view. The J, H, and Ks images cover the cluster core and roughly half of the filament galaxies, which extend toward the neighboring cluster, Abell 1770. This first, in a series of papers on Abell 1763, discusses the data reduction methods and source extraction techniques used for each data set. We present catalogs of infrared sources (with 24 and/or 70um emission) and their corresponding emission in the optical (u', g', r', i', z'), and near- to far-IR (J, H, Ks, IRAC, and MIPS 160um). We provide the catalogs and reduced images to the community through the NASA/IPAC Infrared Science Archive.
700. A2125 in X-ray
- ID:
- ivo://CDS.VizieR/J/ApJ/611/821
- Title:
- A2125 in X-ray
- Short Name:
- J/ApJ/611/821
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an 82ks Chandra ACIS-I observation of a large-scale hierarchical complex, which consists of various clusters/groups of galaxies and low surface brightness X-ray emission at z=0.247. This high-resolution Chandra observation allows us for the first time to separate unambiguously the X-ray contributions from discrete sources and large-scale diffuse hot gas. We detect 99 X-ray sources in a 17{arcmin}x17{arcmin} field.
