- ID:
- ivo://CDS.VizieR/J/ApJ/810/157
- Title:
- V471 Tau system: RVs and BVRI LCs
- Short Name:
- J/ApJ/810/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V471 Tauri, a white dwarf-red dwarf eclipsing binary (EB) in the Hyades, is well known for stimulating development of common envelope theory, whereby novae and other cataclysmic variables form from much wider binaries by catastrophic orbit shrinkage. Our evaluation of a recent imaging search that reported negative results for a much postulated third body shows that the object could have escaped detection or may have actually been seen. The balance of evidence continues to favor a brown dwarf companion about 12 AU from the EB. A recently developed algorithm finds unified solutions from three data types. New radial velocities (RVs) of the red dwarf and BVRcIc light curves are solved simultaneously along with white dwarf and red dwarf RVs from the literature, uvby data, the Microvariability and Oscillations of Stars mission light curve, and 40 years of eclipse timings. Precision-based weighting is the key to proper information balance among the various data sets. Timewise variation of modeled starspots allows unified solution of multiple data eras. Light-curve amplitudes strongly suggest decreasing spottedness from 1976 to about 1980, followed by approximately constant spot coverage from 1981 to 2005. An explanation is proposed for lack of noticeable variation in 1981 light curves, in terms of competition between spot and tidal variations. Photometric-spectroscopic distance is estimated. The red dwarf mass comes out larger than normal for a K2 V star, and even larger than adopted in several structure and evolution papers. An identified cause for this result is that much improved red dwarf RV curves now exist.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/642/A133
- Title:
- V830 Tau VI light curves and RV curves
- Short Name:
- J/A+A/642/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detecting and characterising exoworlds around very young stars (age<=10Myr) are key aspects of exoplanet demographic studies, especially for understanding the mechanisms and timescales of planet formation and migration. Any reliable theory for such physical phenomena requires a robust observational database to be tested. However, detection using the radial velocity method alone can be very challenging because the amplitude of the signals caused by the magnetic activity of such stars can be orders of magnitude larger than those induced even by massive planets. We observed the very young (~2Myr) and very active star V830 Tau with the HARPS-N spectrograph between October 2017 and March 2020 to independently confirm and characterise the previously reported hot Jupiter V830 Tau b (K_b_=68+/-11ms; m_b_sini_b_=0.57+/-0.10M_jup_; P_b_=4.927+/-0.008d). Because of the observed ~1km/s radial velocity scatter that can clearly be attributed to the magnetic activity of V830 Tau, we analysed radial velocities extracted with different pipelines and modelled them using several state-of-the-art tools. We devised injection-recovery simulations to support our results and characterise our detection limits. The analysis of the radial velocities was aided by a characterisation of the stellar activity using simultaneous photometric and spectroscopic diagnostics. Despite the high quality of our HARPS-N data and the diversity of tests we performed, we were unable to detect the planet V830 Tau b in our data and cannot confirm its existence. Our simulations show that a statistically significant detection of the claimed planetary Doppler signal is very challenging. It is important to continue Doppler searches for planets around young stars, but utmost care must be taken in the attempt to overcome the technical difficulties to be faced in order to achieve their detection and characterisation. This point must be kept in mind when assessing their occurrence rate, formation mechanisms, and migration pathways, especially without evidence of their existence from photometric transits.
- ID:
- ivo://CDS.VizieR/J/MNRAS/491/5966
- Title:
- V-types Main Set and HED meteorites catalogues
- Short Name:
- J/MNRAS/491/5966
- Date:
- 19 Jan 2022 13:16:47
- Publisher:
- CDS
- Description:
- We aim to determine the distribution of basaltic asteroids (classified as V-types) based on the spectrophotometric data reported in the MOVIS-C catalogue. A total of 782 asteroids were identified. The observations with all four filters (Y, J, H, Ks), available for 297 of these candidates, allow a reliable comparison with the laboratory data of howardite, eucrite, and diogenite meteorites. We found that the majority of the basaltic candidates (~95 per cent) are located in the inner main belt, while only 29 (~4 per cent) and 8 (~1 per cent) are located in the middle (MMB) and outer main belt (OMB), respectively. A fraction of ~33 per cent from the V-type candidates is associated with the Vesta family (with respect to AstDyS). We also identified four MMB V-type candidates belonging to (15) Eunomia family, and another four low inclination ones corresponding to (135) Hertha. We report differences between the colour indices and albedo distributions of the V-type candidates located in the inner main belt compared to those from the MMB and OMB. These results support the hypothesis of a different origin for the basaltic asteroids with a semimajor axis beyond 2.5au. Furthermore, lithological differences are present between the vestoids and the inner low inclination basaltic asteroids. The data allow us to estimate the unbiased distribution of basaltic asteroids across the main asteroid belt. We highlight that at least 80 per cent of the ejected basaltic material from (4) Vesta is missing or is not yet detected because it is fragmented in sizes smaller than 1km.
23204. V1794 UBVR time series
- ID:
- ivo://CDS.VizieR/J/A+A/351/212
- Title:
- V1794 UBVR time series
- Short Name:
- J/A+A/351/212
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Standard Johnson UBVRI photometry of V1794 Cyg (HD 199178) between 1975 and 1995 is analysed. Instead of the traditional constant period ephemeris, we determine the seasonal periodicities (P_phot_) and the primary and secondary minima epochs (t_min,1_, t_min,2_) of the normalized UBVRI magnitudes using the three stage period analysis (TSPA) and complementary methods.
- ID:
- ivo://CDS.VizieR/J/A+A/572/A41
- Title:
- VUDS Dicovery of a high-redshift protocluster
- Short Name:
- J/A+A/572/A41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using new spectroscopic observations obtained as part of the VIMOS Ultra-Deep Survey (VUDS), we performed a systematic search for overdense environments in the early universe (z>2) and report here on the discovery of Cl J0227-0421, a massive protocluster at z=3.29. This protocluster is characterized by both the large overdensity of spectroscopically confirmed members, delta_gal=10.5+/-2.8, and a significant overdensity in photometric redshift members. The halo mass of this protocluster is estimated by a variety of methods to be ~3x10^14^M_{sun}_ at z~3.3, which, evolved to z=0 results in a halo mass rivaling or exceeding that of the Coma cluster. The properties of 19 spectroscopically confirmed member galaxies are compared with a large sample of VUDS/VVDS galaxies in lower density field environments at similar redshifts. We find tentative evidence for an excess of redder, brighter, and more massive galaxies within the confines of the protocluster relative to the field population, which suggests that we may be observing the beginning of environmentally induced quenching. The properties of these galaxies are investigated, including a discussion of the brightest protocluster galaxy, which appears to be undergoing vigorous coeval nuclear and starburst activity. The remaining member galaxies appear to have characteristics that are largely similar to the field population. Though we find weaker evidence of the suppression of the median star formation rates among and differences in the stacked spectra of member galaxies with respect to the field, we defer any conclusions about these trends to future work with the ensemble of protostructures that are found in the full VUDS sample.
- ID:
- ivo://lam.cesam.aspic/vuds_dr1/q/ssa
- Title:
- VUDS-DR1 - Simple Spectrum Access
- Short Name:
- VUDS-DR1 SSAP
- Date:
- 24 Aug 2021 14:22:48
- Publisher:
- The CeSAM VO team
- Description:
- Spectra from the VIMOS Ultra–Deep Survey (VUDS) DR1 release
- ID:
- ivo://CDS.VizieR/J/A+A/568/L8
- Title:
- VUDS extreme emission line 0.2<~z<~0.9 galaxies
- Short Name:
- J/A+A/568/L8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 31 low-luminosity (-14.5>~M_AB_(B)>~-18.8), extreme emission line galaxies (EELGs) at 0.2<~z<~0.9 identified by their unusually high rest-frame equivalent widths (100<=EW[OIII]<=1700{AA}) as part of the VIMOS Ultra Deep Survey (VUDS). VIMOS optical spectra of unprecedented sensitivity (I_AB_~25mag) along with multiwavelength photometry and HST imaging are used to investigate spectrophotometric properties of this unique sample and to explore, for the first time, the very low stellar mass end (M_*_<~10^8^M_{sun}_) of the luminosity-metallicity (LZR) and mass-metallicity (MZR) relations at z<1. Characterized by their extreme compactness (R_50_<1kpc), low stellar mass and enhanced specific star formation rates (sSFR=SFR/M_*_~10^-9^-10^-7^yr^-1^), the VUDS EELGs are blue dwarf galaxies likely experiencing the first stages of a vigorous galaxy-wide starburst. Using Te-sensitive direct and strong-line methods, we find that VUDS EELGs are low-metallicity (7.5<~12+log(O/H)<~8.3) galaxies with high ionization conditions (log(q_ion_)>~8cm/s), including at least three EELGs showing HeII{lambda}4686{AA} emission and four extremely metal-poor (<~10% solar) galaxies. The LZR and MZR followed by VUDS EELGs show relatively large scatter, being broadly consistent with the extrapolation toward low luminosity and mass from previous studies at similar redshift. However, we find evidence that galaxies with younger and more vigorous star formation --as characterized by their larger EWs, ionization and sSFR-- tend to be more metal poor at a given stellar mass.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A97
- Title:
- VUDS UV and Ly{alpha} luminosity functions
- Short Name:
- J/A+A/634/A97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The star formation rate density (SFRD) evolution presents an area of great interest in the studies of galaxy evolution and reionization. The current constraints of SFRD at z>5 are based on the rest-frame UV luminosity functions with the data from photometric surveys. The VIMOS UltraDeep Survey (VUDS) was designed to observe galaxies at redshifts up to ~6 and opened a window for measuring SFRD at z>5 from a spectroscopic sample with a well-controlled selection function. We establish a robust statistical description of the star-forming galaxy population at the end of cosmic HI reionization (5.0<=z<=6.6) from a large sample of 49 galaxies with spectroscopically confirmed redshifts. We determine the rest-frame UV and Ly{alpha} luminosity functions and use them to calculate SFRD at the median redshift of our sample z=5.6. We selected a sample of galaxies at 5.0<=z_spec_<=6.6 from the VUDS. We cleaned our sample from low redshift interlopers using ancillary photometric data. We identified galaxies with Ly{alpha} either in absorption or in emission, at variance with most spectroscopic samples in the literature where Ly{alpha} emitters (LAE) dominate. We determined luminosity functions using the 1/V_max_ method. The galaxies in this redshift range exhibit a large range in their properties. A fraction of our sample shows strong Ly{alpha} emission, while another fraction shows Ly{alpha} in absorption. UV-continuum slopes vary with luminosity, with a large dispersion. We find that star-forming galaxies at these redshifts are distributed along the main sequence in the stellar mass vs. SFR plane, described with a slope {alpha}=0.85+/-0.05. We report a flat evolution of the specific SFR compared to lower redshift measurements. We find that the UV luminosity function is best reproduced by a double power law, while a fit with a Schechter function is only marginally inferior. The Ly{alpha} luminosity function is best fitted with a Schechter function. We derive a logSFRD_UV_(M_{sun}_/yr/Mpc^3^)=-1.45^+0.06^_-0.08_ and logSFRD_Ly{alpha}_(M_{sun}_/yr/Mpc^3^)=-1.40^+0.07^_-0.08_. The SFRD derived from the Ly{alpha} luminosity function is in excellent agreement with the UV-derived SFRD after correcting for IGM absorption.Conclusions. Our new SFRD measurements at a mean redshift of z=5.6 are ~0.2dex above the mean SFRD reported in Madau & Dickinson (2014ARA&A..52..415M), but in excellent agreement with results from Bouwens et al. (2015ApJ...803...34B). These measurements confirm the steep decline of the SFRD at z>2. The bright end of the Ly{alpha} luminosity function has a high number density, indicating a significant star formation activity concentrated in the brightest LAE at these redshifts. LAE with equivalent width EW>25{AA} contribute to about 75% of the total UV-derived SFRD. While our analysis favors low dust content in 5.0<z<6.6, uncertainties on the dust extinction correction and associated degeneracy in spectral fitting will remain an issue, when estimating the total SFRD until future surveys extending spectroscopy to the NIR rest-frame spectral domain, such as with JWST.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A34
- Title:
- VUV absorption cross section of CO_2_
- Short Name:
- J/A+A/609/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We quantify the temperature dependency of the VUV absorption cross section of carbon dioxide. The VUV absorption cross section of CO_2_ increases with the temperature. The absorption we measured at 150K seems to be close to the absorption of CO_2_ in the fundamental ground state. The absorption cross section can be separated in two parts: a continuum and a fine structure superimposed on the continuum. The variation of the continuum of absorption can be represented by the sum of three gaussian functions. We used these data in our 1D thermo-photochemical model in order to study their impact on the predicted atmospheric composition of warm exoplanets. Using data at high temperature in thermo-photochemical models modifies significantly the abundance and the photodissociation rates of many species, in addition to carbon dioxide, such as methane and ammonia. These deviations have an impact on synthetic transmission spectra, leading to variations of up to 5ppm.
- ID:
- ivo://CDS.VizieR/J/ApJS/150/1
- Title:
- VV29 and NGC 4676 HST photometry
- Short Name:
- J/ApJS/150/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of the faint galaxy population in the Advanced Camera for Surveys (ACS) Early Release Observation fields VV 29 (UGC 10214) and NGC 4676. These observations cover a total area of 26.3arcmin^2^ and have depths close to that of the Hubble Deep Fields in the deepest part of the VV 29 image, with 10{sigma} detection limits for point sources of 27.8, 27.6, and 27.2 AB magnitudes in the g_F475W_, V_F606W_, and I_F814W_ bands, respectively.
