- ID:
- ivo://CDS.VizieR/J/AJ/140/119
- Title:
- {beta}Pic and AB Dor moving groups members
- Short Name:
- J/AJ/140/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from our continuing program to identify new, low-mass, members of the nearby young moving groups (NYMGs) using a proper motion selection algorithm and various observational techniques. We have three goals: (1) to provide high priority targets for exoplanet searches by direct imaging, (2) to complete the census of the membership in the NYMGs down to ~0.1M_{sun}_, and thus (3) provide a well-characterized sample of nearby (median distances at least twice as close as the Taurus and Ophiuchus star-forming regions), young (8-50Myr) stars for detailed study of their physical properties and multiplicity.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/627/A28
- Title:
- beta Pic BRITE, bRing, SMEI light curves
- Short Name:
- J/A+A/627/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exoplanet properties crucially depend on the parameters of their host stars: more accurate stellar parameters yield more accurate exoplanet characteristics. When the exoplanet host star shows pulsations, asteroseismology can be used for an improved description of the stellar parameters. We aim to revisit the pulsational properties of {beta} Pic and identify its pulsation modes from normalized amplitudes in five different passbands. We also investigate the potential presence of a magnetic field. We conducted a frequency analysis using three seasons of BRITE-Constellation observations in the two BRITE filters, the about 620-day-long bRing light curve, and the nearly 8-year-long SMEI photometric time series. We calculated normalized amplitudes using all passbands and including previously published values obtained from ASTEP observations. We investigated the magnetic properties of {beta} Pic using spectropolarimetric observations conducted with the HARPSpol instrument. Using 2D rotating models, we fit the normalized amplitudes and frequencies through Monte Carlo Markov chains. We identify 15 pulsation frequencies in the range from 34 to 55d^-1^, where two, F13 at 53.6917d^-1^ and F11 at 50.4921d^-1^, display clear amplitude variability. We use the normalized amplitudes in up to five passbands to identify the modes as three l=1, six l=2, and six l=3 modes. {beta} Pic is shown to be non-magnetic with an upper limit of the possible undetected dipolar field of 300 Gauss. Multiple fits to the frequencies and normalized amplitudes are obtained, including one with a near equator-on inclination for {beta} Pic, which corresponds to our expectations based on the orbital inclination of {beta} Pic b and the orientation of the circumstellar disk. This solution leads to a rotation rate of 27% of the Keplerian breakup velocity, a radius of 1.497+/-0.025R_{sun}_, and a mass of 1.797+/-0.035M_{sun}_. The ~2% errors in radius and mass do not account for uncertainties in the models and a potentially erroneous mode-identification.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A15
- Title:
- beta Pictoris photometry
- Short Name:
- J/A+A/648/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric monitoring of beta Pictoris in 1981 showed anomalous fluctuations of up to 4% over several days, consistent with foreground material transiting the stellar disk. The subsequent discovery of the gas giant planet beta Pictoris b and the predicted transit of its Hill sphere to within 0.1 au projected distance of the planet provided an opportunity to search for the transit of a circumplanetary disk in this 21+/-4Myr-old planetary system. Continuous broadband photometric monitoring of beta Pictoris requires ground- based observatories at multiple longitudes to provide redundancy and to provide triggers for rapid spectroscopic followup. These observatories include the dedicated beta Pictoris monitoring observatory bRing at Sutherland and Siding Springs, the ASTEP400 telescope at Concordia, and observations from the space observatories BRITE and Hubble Space Telescope. We search the combined light curves for evidence of short period transient events caused by rings and for longer term photometric variability due to diffuse circumplanetary material. We find no photometric event that matches with the event seen in November 1981, and there is no systematic photometric dimming of the star as a function of the Hill sphere radius. We conclude that the 1981 event was not caused by the transit of a circumplanetary disk around beta Pictoris b. The upper limit on the long term variability of beta Pictoris places an upper limit of 1.8x10^22^g of dust within the Hill sphere. Circumplanetary material is either condensed into a non-transiting disk, is condensed into a disk with moons that has a small obliquity, or is below our detection threshold. This is the first time that a dedicated international campaign has mapped the Hill sphere transit of a gas giant extrasolar planet at 10 au.
434. Bet Aur light curves
- ID:
- ivo://CDS.VizieR/J/A+A/467/1215
- Title:
- Bet Aur light curves
- Short Name:
- J/A+A/467/1215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the most precise light curve ever obtained of a detached eclipsing binary star and use it investigate the inclusion of non-linear limb darkening laws in light curve models of eclipsing binaries. This light curve, of the bright eclipsing system beta Aurigae, was obtained using the star tracker aboard the WIRE satellite and contains 30000 datapoints with a point-to-point scatter of 0.3mmag. We analyse the WIRE light curve using a version of the EBOP code modified to include non-linear limb darkening laws and to directly incorporate observed times of minimum light and spectroscopic light ratios into the photometric solution as individual observations. We also analyse the dataset with the Wilson-Devinney code to ensure that the two models give consistent results. EBOP is able to provide an excellent fit to the high-precision WIRE data. Whilst the fractional radii of the stars are only defined to a precision of 5% by this light curve, including an accurate published spectroscopic light ratio improves this dramatically to 0.5%. Using non-linear limb darkening improves the quality of the fit significantly compared to the linear law and causes the measured radii to increase by 0.4%. It is possible to derive all of the limb darkening coefficients from the light curve, although they are strongly correlated with each other. The fitted coefficients agree with theoretical predictions to within their fairly large error estimates. We were able to obtain a reasonably good fit to the data using the Wilson- Devinney code, but only using the highest available integration accuracy and by iterating for a long time. Bolometric albedos of 0.6 were found, which are appropriate to convective rather than radiative envelopes. The radii and masses of the components of beta Aurigae are R_A_=2.762+/-0.017R_{sun}_, R_B_=2.568+/-0.017R_{sun}_, M_A_=2.376+/-0.027M_{sun}_ and M_B_=2.291+/-0.027M_{sun}_, where A and B denote the primary and secondary star, respectively. Theoretical stellar evolutionary models can match these parameters for a solar metal abundance and an age of 450 to 500Myr. The Hipparcos trigonometric parallax and an interferometrically-derived orbital parallax give distances to beta Aurigae which are in excellent agreement with each other and with distances derived using surface brightness relations and several sets of empirical and theoretical bolometric corrections.
- ID:
- ivo://CDS.VizieR/J/MNRAS/388/1198
- Title:
- Be/X-ray binaries in Small Magellanic Cloud
- Short Name:
- J/MNRAS/388/1198
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectral distributions of Be/X-ray binaries in the Large Magellanic Cloud and Galaxy have been shown to differ significantly from the distribution of isolated Be stars in the Galaxy. Population synthesis models can explain this difference in spectral distributions through substantial angular momentum loss from the binary system. In this work, we explore the spectral distribution of Be/X-ray binaries in the Small Magellanic Cloud (SMC) using high signal-to-noise ratio spectroscopy of a sample of 37 optical counterparts to known X-ray pulsars. Our results show that the spectral distribution of Be/X-ray binaries in the SMC is consistent with that of the Galaxy, despite the lower metallicity environment of the SMC. This may indicate that, although the metallicity of the SMC is conducive to the formation of a large number of high-mass X-ray binaries, the spectral distribution of these systems is likely to be most strongly influenced by angular momentum losses during binary evolution, which are not particularly dependent on the local metallicity.
- ID:
- ivo://CDS.VizieR/J/A+A/362/673
- Title:
- BF Aur UBV photometry
- Short Name:
- J/A+A/362/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Because the question of the mass ratio of the early-type system BF Aur has not yet fully been clarified, we present and analyse new UBV photometry and nearly contemporaneous radial velocity observations. From a simultaneous least squares analysis of the photometric light curves and the new radial velocity curves we derive a mass ratio of q=1.048+/-0.02. With even much more accurate photometric and spectroscopic data the mass ratio remains weakly defined. The resulting stellar parameters are consistent with the line ratios derived from old and our new spectra and available Stroemgren indices. We confirm earlier conclusions that BF Aur is detached and that the more massive component is almost filling its Roche lobe. New data indicating a period change support the interpretation that mass exchange has already started or is about to start.
437. B3 0003+387 field
- ID:
- ivo://CDS.VizieR/J/AJ/120/2331
- Title:
- B3 0003+387 field
- Short Name:
- J/AJ/120/2331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present evidence for a significant overdensity of red galaxies, as much as a factor of 14 over comparable field samples, in the field of the z=1.47 radio galaxy B3 0003+387. The colors and luminosities of the brightest red galaxies are consistent with their being at z>0.8. The radio galaxy and one of the red galaxies are separated by 5" and show some evidence of a possible interaction. However, the red galaxies do not show any strong clustering around the radio galaxy or around any of the brighter red galaxies. The data suggest that we are looking at a wall or sheet of galaxies, possibly associated with the radio galaxy at z=1.47. Spectroscopic redshifts of these red galaxies will be necessary to confirm this large-scale structure.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/60
- Title:
- Bgri light curves of PTF11kmb and PTF12bho
- Short Name:
- J/ApJ/836/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Palomar Transient Factory discoveries and the photometric and spectroscopic observations of PTF11kmb and PTF12bho. We show that both transients have properties consistent with the class of calcium-rich gap transients, specifically lower peak luminosities and rapid evolution compared to ordinary supernovae, and a nebular spectrum dominated by [CaII] emission. A striking feature of both transients is their host environments: PTF12bho is an intracluster transient in the Coma Cluster, while PTF11kmb is located in a loose galaxy group, at a physical offset ~150kpc from the most likely host galaxy. Deep Subaru imaging of PTF12bho rules out an underlying host system to a limit of M_R_>-8.0mag, while Hubble Space Telescope imaging of PTF11kmb reveals a marginal counterpart that, if real, could be either a background galaxy or a globular cluster. We show that the offset distribution of Ca-rich gap transients is significantly more extreme than that seen for SNe Ia or even short-hard gamma-ray bursts (sGRBs). Thus, if the offsets are caused by a kick, they require higher kick velocities and/or longer merger times than sGRBs. We also show that almost all Ca-rich transients found to date are in group and cluster environments with elliptical host galaxies, indicating a very old progenitor population; the remote locations could partially be explained by these environments having the largest fraction of stars in the intragroup/intracluster light following galaxy-galaxy interactions.
- ID:
- ivo://CDS.VizieR/J/A+AS/115/219
- Title:
- Bgr survey of Cl1613+3104 and Cl1600+4109
- Short Name:
- J/A+AS/115/219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
440. BH 176 and AM-2
- ID:
- ivo://CDS.VizieR/J/A+A/300/726
- Title:
- BH 176 and AM-2
- Short Name:
- J/A+A/300/726
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained VI photometry for two low Galactic latitude star clusters: BH 176 and AM-2, using the 2.2m and the 3.5m NTT telescopes at ESO. Their VI colour-magnitude diagrams reveal that: BH 176 may be a globular cluster, or a border line object between a globular cluster and a disk cluster, showing a red horizontal branch and an extended red giant branch. We estimate E(B-V)=0.77 and d_{sun}_=13.4kpc. AM-2 appears to be an intermediate age open cluster, for which a reddening E(B-V)=0.44 and d_{sun}_=12.4kpc are estimated. It is located in the outer regions of the Galactic disk.
