- ID:
- ivo://CDS.VizieR/J/A+A/659/A74
- Title:
- CHEOPS phase curve of WASP-189 b
- Short Name:
- J/A+A/659/A74
- Date:
- 10 Mar 2022 06:44:26
- Publisher:
- CDS
- Description:
- Gas giants orbiting close to hot and massive early-type stars can reach dayside temperatures that are comparable to those of the coldest stars. These "ultra-hot Jupiters" have atmospheres made of ions and atomic species from molecular dissociation and feature strong day-to-night temperature gradients. Photometric observations at different orbital phases provide insights on the planet atmospheric properties. We analyse the photometric observations of WASP-189 acquired with the instrument CHEOPS to derive constraints on the system architecture and the planetary atmosphere. We implement a light curve model suited for asymmetric transit shape caused by the gravity-darkened photosphere of the fast-rotating host star. We also model the reflective and thermal components of the planetary flux, the effect of stellar oblateness and light-travel time on transit-eclipse timings, the stellar activity and CHEOPS systematics. From the asymmetric transit, we measure the size of the ultra-hot Jupiter WASP-189, R_p_=1.600_-0.016_^+0.017^R_J_, with a precision of 1%, and the true orbital obliquity of the planetary system {Psi}_p_=89.6+/-1.2deg (polar orbit). We detect no significant hotspot offset from the phase curve and obtain an eclipse depth {delta}_ecl_=96.5_-5.0_^+4.5^ppm, from which we derive an upper limit on the geometric albedo: A_g_<0.48. We also find that the eclipse depth can only be explained by thermal emission alone in the case of extremely inefficient energy redistribution. Finally, we attribute the photometric variability to the stellar rotation, either through superficial inhomogeneities or resonance couplings between the convective core and the radiative envelope. Based on the derived system architecture, we predict the eclipse depth in the upcoming TESS observations to be up to ~165ppm. High-precision detection of the eclipse in both CHEOPS and TESS passbands might help disentangle between reflective and thermal contributions. We also expect the right ascension of the ascending node of the orbit to precess due to the perturbations induced by the stellar quadrupole moment J_2_ (oblateness).
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- ID:
- ivo://CDS.VizieR/J/A+A/657/A52
- Title:
- CHEOPS transit light curves of WASP-103 b
- Short Name:
- J/A+A/657/A52
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Ultra-short period planets undergo strong tidal interactions with their host star which lead to planet deformation and orbital tidal decay. WASP-103b is the exoplanet with the highest expected deformation signature in its transit light curve and one of the shortest expected spiral-in times. Measuring the tidal deformation of the planet would allow us to estimate the second degree fluid Love number and gain insight into the planet's internal structure. Moreover, measuring the tidal decay timescale would allow us to estimate the stellar tidal quality factor, which is key to constraining stellar physics. We obtained 12 transit light curves of WASP-103b with the CHaracterising ExOplanet Satellite (CHEOPS) to estimate the tidal deformation and tidal decay of this extreme system. We modelled the high-precision CHEOPS transit light curves together with systematic instrumental noise using multi-dimensional Gaussian process regression informed by a set of instrumental parameters. To model the tidal deformation, we used a parametrisation model which allowed us to determine the second degree fluid Love number of the planet. We combined our light curves with previously observed transits of WASP-103b with the Hubble Space Telescope (HST) and Spitzer to increase the signal-to-noise of the light curve and better distinguish the minute signal expected from the planetary deformation. We estimate the radial Love number of WASP-103b to be h_f_=1.59+/-0.53 This is the first time that the tidal deformation is directly detected (at 3 sigma) from the transit light curve of an exoplanet. Combining the transit times derived from CHEOPS, HST, and Spitzer light curves with the other transit times available in the literature, we find no significant orbital period variation for WASP-103b. However, the data show a hint of an orbital period increase instead of a decrease, as is expected for tidal decay. This could be either due to a visual companion star if this star is bound, the Applegate effect, or a statistical artefact. The estimated Love number of WASP-103b is similar to Jupiters. This will allow us to constrain the internal structure and composition of WASP-103b, which could provide clues on the inflation of hot Jupiters. Future observations with James Webb Space Telescope (JWST) can better constrain the radial Love number of WASP-103b due to their high signal-to-noise and the smaller signature of limb darkening in the infrared. A longer time baseline is needed to constrain the tidal decay in this system.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A94
- Title:
- CHEOPS WASP-189 b transit light curve
- Short Name:
- J/A+A/643/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CHEOPS (CHaracterising ExOPlanets Satellite), launched in December 2019, is a space mission dedicated to exoplanet follow-up with the capacity to perform photometric measurements at the20 ppm level. As CHEOPS observes in a broad optical passband, it can be used provide insights on the reflected light from exoplanets, and constrain the short-wavelength thermal emission for the hottest of planets through the observation of occultations and phase curves. We here report the first observation of an occultation by CHEOPS: that of the hot Jupiter WASP-189b, a M~2M_J_ planet orbiting an A-type star. We detect the occultation of WASP-189b at high significance in individual measurements, and derive an occultation depth of dF=87.9+/-4.3 ppm based on four occultations. We compare this measurement to model predictions and find that, when assuming inefficient heat redistribution, they are consistent with an unreflective atmosphere, heated to a temperature of 3435+/-27K. We furthermore present two transits of WASP-189b observed by CHEOPS. These transits have an asymmetric shape that we attribute to gravity darkening of the host star due to its high rotation rate. We use these measurements to refine the planetary parameters, finding a ~25% deeper transit compared to the discovery paper and updating the radius of WASP-189b to 1.619+/-0.021R_J_. We further measure the projected orbital obliquity to be lambda=86.4(+2.9,-4.4)deg, a value in good agreement with a previous measurement from spectroscopic observations, and derive a true obliquity of Psi=85.4+/-4.3deg. Finally, we provide reference values for the photometric precision attained by the CHEOPS satellite: for the V=6.6 mag star, and using a 1-hour binning, we obtain a residual RMS between 10 and 17ppm on the individual light curves, and 5.7ppm when combining four visits.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/268
- Title:
- Cheshire Cat galaxies: redshifts and magnitudes
- Short Name:
- J/ApJ/806/268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cheshire Cat is a relatively poor group of galaxies dominated by two luminous elliptical galaxies surrounded by at least four arcs from gravitationally lensed background galaxies that give the system a humorous appearance. Our combined optical/X-ray study of this system reveals that it is experiencing a line of sight merger between two groups with a roughly equal mass ratio with a relative velocity of ~1350 km/s. One group was most likely a low-mass fossil group, while the other group would have almost fit the classical definition of a fossil group. The collision manifests itself in a bimodal galaxy velocity distribution, an elevated central X-ray temperature and luminosity indicative of a shock, and gravitational arc centers that do not coincide with either large elliptical galaxy. One of the luminous elliptical galaxies has a double nucleus embedded off-center in the stellar halo. The luminous ellipticals should merge in less than a Gyr, after which observers will see a massive 1.2-1.5x10^14^ M_{sun}_ fossil group with an M_r_=-24.0 brightest group galaxy at its center. Thus, the Cheshire Cat offers us the first opportunity to study a fossil group progenitor. We discuss the limitations of the classical definition of a fossil group in terms of magnitude gaps between the member galaxies. We also suggest that if the merging of fossil (or near-fossil) groups is a common avenue for creating present-day fossil groups, the time lag between the final galactic merging of the system and the onset of cooling in the shock-heated core could account for the observed lack of well-developed cool cores in some fossil groups.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/156
- Title:
- CH(G) index of SDSS evolved stars
- Short Name:
- J/ApJ/765/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured the CH G band (CH(G)) index for evolved stars in the globular cluster M3 based on the Sloan Digital Sky Survey (SDSS) spectroscopic survey. It is found that there is a useful way to select red giant branch (RGB) stars from the contamination of other evolved stars such as asymptotic giant branch (AGB) and red horizontal branch (RHB) stars by using the CH(G) index versus (g-r)_0_ diagram if the metallicity is known from the spectra. When this diagram is applied to field giant stars with similar metallicity, we establish a calibration of CH(G)=1.625(g-r)_0_-1.174(g-r)^2^_0_-0.934. This method is confirmed by stars with [Fe/H]~-2.3 where spectra of member stars in globular clusters M15 and M92 are available in the SDSS database. We thus extend this kind of calibration to every individual metallicity bin ranging from [Fe/H]~-3.0 to [Fe/H]~0.0 by using field red giant stars with 0.4<=(g-r)_0_<=1.0. The metallicity-dependent calibrations give CH(G)=1.625(g-r)_0_-1.174(g-r)^2^_0_+0.060[Fe/H]-0.830 for -3.0<[Fe/H]<=-1.2 and CH(G)=0.953(g-r)_0_-0.655(g-r)^2^_0_+0.060[Fe/H]-0.650 for -1.2<[Fe/H]<0.0. The calibrations are valid for the SDSS spectroscopic data set, and they cannot be applied blindly to other data sets. With the two calibrations, a significant number of the contaminating stars (AGB and RHB stars) were excluded and thus a clear sample of red giant stars is obtained by selecting stars within +/-0.05mag of the calibration. The sample is published online and it is expected that this large and clean sample of RGB stars will provide new information on the formation and evolution of the Galaxy.
- ID:
- ivo://CDS.VizieR/J/A+AS/125/149
- Title:
- CHIANTI - An Atomic Database For Emission Lines I.
- Short Name:
- J/A+AS/125/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A comprehensive set of accurate atomic data is required for analyses of astrophysical and solar spectra. CHIANTI provides a database of atomic energy levels, wavelengths, radiative data and electron excitation data for ions which are abundant in cosmic plasmas. The most recent electron excitation data have been assessed and stored following the method of Burgess & Tully (1992A&A...254..436B). The current version is essentially complete for specifying the emission spectrum at wavelengths greater than 50{AA}. A list of observed lines in the spectral region between 50 and 1100{AA} has been compiled and compared with the lines predicted by the CHIANTI database. The CHIANTI database reproduces the vast majority of lines observed at these wavelengths. CHIANTI includes IDL (Interactive Data Language) routines to calculate optically thin synthetic spectra for equilibrium conditions. IDL routines to calculate theoretical line intensities required for electron density or temperature diagnostics and emission measure studies are also included. The CHIANTI atomic database and supporting IDL routines are available by anonymous FTP.
- ID:
- ivo://CDS.VizieR/J/ApJS/212/13
- Title:
- ChIcAGO. I. Sample and initial results
- Short Name:
- J/ApJS/212/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Chasing the Identification of ASCA Galactic Objects (ChIcAGO) survey, which is designed to identify the unknown X-ray sources discovered during the ASCA Galactic Plane Survey (AGPS). Little is known about most of the AGPS sources, especially those that emit primarily in hard X-rays (2-10keV) within the F_x_~10^-13^ to 10^-11^erg/cm2/s X-ray flux range. In ChIcAGO, the subarcsecond localization capabilities of Chandra have been combined with a detailed multiwavelength follow-up program, with the ultimate goal of classifying the >100 unidentified sources in the AGPS. Overall to date, 93 unidentified AGPS sources have been observed with Chandra as part of the ChIcAGO survey. A total of 253 X-ray point sources have been detected in these Chandra observations within 3' of the original ASCA positions. We have identified infrared and optical counterparts to the majority of these sources, using both new observations and catalogs from existing Galactic plane surveys. X-ray and infrared population statistics for the X-ray point sources detected in the Chandra observations reveal that the primary populations of Galactic plane X-ray sources that emit in the F_x_~10^-13^ to 10^-11^ erg/cm2/s flux range are active stellar coronae, massive stars with strong stellar winds that are possibly in colliding wind binaries, X-ray binaries, and magnetars. There is also another primary population that is still unidentified but, on the basis of its X-ray and infrared properties, likely comprises partly Galactic sources and partly active galactic nuclei.
- ID:
- ivo://nasa.heasarc/chicagocxo
- Title:
- ChIcAGO Survey Chandra X-Ray Source Catalog
- Short Name:
- CHICAGOCXO
- Date:
- 09 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from the 'Chasing the Identification of ASCA Galactic Objects' (ChIcAGO) survey, which is designed to identify the unknown X-ray sources discovered during the ASCA Galactic Plane Survey (AGPS). Little is known about most of the AGPS sources, especially those that emit primarily in hard X-rays (2-10 keV) within the X-ray flux range from ~ 10<sup>-13</sup> to 10<sup>-11</sup> erg cm<sup>-2</sup> s<sup>-1</sup>. In ChIcAGO, the sub-arcsecond localization capabilities of Chandra have been combined with a detailed multi-wavelength follow-up program, with the ultimate goal of classifying the > 100 unidentified sources in the AGPS. Overall to date, 93 unidentified AGPS sources have been observed with Chandra as part of the ChIcAGO survey. A total of 253 X-ray point sources have been detected in these Chandra observations within 3 arcminutes of the original ASCA positions. The authors have identified infrared and optical counterparts to the majority of these sources, using both new observations and catalogs from existing Galactic plane surveys. X-ray and infrared population statistics for the X-ray point sources detected in the Chandra observations reveal that the primary populations of Galactic plane X-ray sources that emit in the X-ray flux range from ~ 10<sup>-13</sup> to 10<sup>-11</sup> erg cm<sup>-2</sup> s<sup>-1</sup> are active stellar coronae, massive stars with strong stellar winds that are possibly in colliding wind binaries, X-ray binaries, and magnetars. There is also another primary population that is still unidentified but, on the basis of its X-ray and infrared properties, likely comprises partly Galactic sources and partly active galactic nuclei. A total of 93 AGPS sources have been observed with Chandra as part of the ChIcAGO survey, of which 84 were imaged with ACIS-S and 9 were imaged with HRC-I. The ChIcAGO Chandra observations took place over a 3.5 yr period, from 2007 January to 2010 July. The Chandra exposure times ranged from ~ 1 to 10 ks. All the details of these Chandra observations are listed in Table 1 of the reference paper. The initial automated analysis of these Chandra observations was conducted using the ChIcAGO Multi-wavelength Analysis Pipeline (MAP), described in Section 2.2 of the reference paper. ChIcAGO MAP takes the ACIS-S or HRC-I Chandra observation of an AGPS source field and detects and analyzes all point sources within 3 arcminutes, equivalent to the largest likely position error, for the original AGPS source positions supplied by Sugizaki et al. (2001, ApJS, 134, 77). The authors then performed a more detailed X-ray analysis and counterpart study for those 74 sources with > 20 X-ray counts, as such sources are approximately within the original AGPS sources X-ray flux range (see Sections 3.2 and 3.3 of the reference paper). Infrared and optical follow-up were primarily performed on those ChIcAGO sources having > 20 X-ray counts. In order to determine which optical and infrared sources are counterparts to ChIcAGO sources, the authors used a technique similar to that described by Zhao et al. (2005, ApJS, 161, 429), using their Equation (11). If the separation between a ChIcAGO source's wavdetect position and its possible counterpart is less than the quadratic sum of their 3-sigma positional errors and the 3-sigma Chandra pointing error, then the X-ray and optical (or infrared) sources are likely to be associated. The 1-sigma positional errors for all sources in the 2MASS PSC and GLIMPSE catalogs are 0.1 arcseconds and 0.3 arcseconds, respectively. USNO B has an astrometric accuracy of < 0.25 arcseconds. The authors have assumed that the error distributions of the Chandra observations, Chandra pointing, and USNO B Catalog are all Gaussian for the purposes of identifying possible counterparts to the ChIcAGO sources. This table was created by the HEASARC in June 2014 based on electronic versions of Tables 1, 2 and 12 from the reference paper which were obtained from the ApJS website. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/A+A/658/A6
- Title:
- 3C293 high and low resolution maps
- Short Name:
- J/A+A/658/A6
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Active galactic nuclei (AGNs) show episodic activity, which can be evident in galaxies that exhibit restarted radio jets. These restarted jets can interact with their environment, leaving signatures on the radio spectral energy distribution. Tracing these signatures is a powerful way to explore the life of radio galaxies. This requires resolved spectral index measurements over a broad frequency range including low frequencies. We present such a study for the radio galaxy 3C293, which has long been thought to be a restarted galaxy on the basis of its radio morphology. Using the International LOFAR telescope (ILT) we probed spatial scales as fine as ~0.2-arcsec at 144MHz, and to constrain the spectrum we combined these data with Multi-Element Radio Linked Interferometer Network (MERLIN) and Very Large Array (VLA) archival data at frequencies up to 8.4GHz that have a comparable resolution. In the inner lobes (~2kpc), we detect the presence of a spectral turnover that peaks at ~225MHz and is most likely caused by free-free absorption from the rich surrounding medium. We confirm that these inner lobes are part of a jet-dominated young radio source (spectral age ~0.17Myr), which is strongly interacting with the rich int <0.27Myr. The outer lobes (extending up to ~100kpc) have a spectral index of ~0.6-0.8 from 144-4850MHz with a remarkably uniform spatial distribution and only mild spectral curvature. We propose that intermittent fuelling and jet flow disruptions are powering the mechanisms that keep the spectral index in the outer lobes from steepening and maintain the spatial uniformity of the spectral index. Overall, it appears that 3C293 has gone through multiple (two to three) epochs of activity. This study adds 3C293 to the new sub-group of restarted galaxies with short interruption time periods. This is the first time a spatially resolved study has been performed that simultaneously studies a young source as well as the older outer lobes at such low frequencies. This illustrates the potential of the International LOFAR telescope to expand such studies to a larger sample of radio galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/576/A122
- Title:
- 3C 273 high energy spectrum
- Short Name:
- J/A+A/576/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The high energy spectrum of 3C 273 is usually understood in terms of inverse-Compton emission in a relativistic leptonic jet. This model predicts variability patterns and delays that could be tested with simultaneous observations from the radio to the GeV range. The instruments IBIS, SPI, JEM-X on board INTEGRAL, PCA on board RXTE, and LAT on board Fermi have enough sensitivity to follow the spectral variability of 3C 273 from the keV to the GeV. We looked for correlations between the different energy bands, including radio data at 37GHz collected at the Metsahovi Radio Observatory and built quasi-simultaneous multiwavelength spectra in the high energy domain when the source is flaring either in the X-rays or in the {gamma} rays.
