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- ID:
- ivo://CDS.VizieR/J/AJ/110/1350
- Title:
- Beta Lyrae light curve changes
- Short Name:
- J/AJ/110/1350
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We apply a variety of classical and recently developed periodicity analyses to light curves of Beta Lyrae in 9 eras that extend over a range of about 150 years. Some new data are tabulated. Most periodic variations that have been reported in the literature do not pass standard significance tests, according to our adopted criteria. Certain other periods do pass the tests, although most do so only for one, or at most two, data sets. Our main findings are that a period of about 9 months is present in all data sets and that it connects extremely well in phase from era to era, all the way back to Baxendell's observations of 1840-1877. The semiamplitude is small but reasonably consistent, averaging about 2% of the flux in the light curve maxima. Any substantially larger excursions that occur are nonperiodic. Phase coherence of the 9 month period is fairly good, even with a linear ephemeris, and becomes excellent if one allows for a slow sinusoidal variation of the 9 month periodicity. There is some evidence for a monotonic decrease in the amplitude of the 9 month periodicity with increasing wavelength.
1783. {beta} Lyr light curves
- ID:
- ivo://CDS.VizieR/J/A+A/618/A112
- Title:
- {beta} Lyr light curves
- Short Name:
- J/A+A/618/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mass exchange and mass loss in close binaries can significantly affect their evolution, but a complete self-consistent theory of these processes is still to be developed. Processes such as radiative shielding due to a hot-spot region, or a hydrodynamical interaction of different parts of the gas stream have been studied previously. In order to test the respective predictions, it is necessary to carry out detailed observations of binaries undergoing the largescale mass exchange, especially for those that are in the rapid transfer phase. {beta} Lyr A is an archetype of such a system, having a long and rich observational history. Our goal for this first study is to quantitatively estimate the geometry and physical properties of the optically thick components, namely the Roche-lobe filling mass-losing star, and the accretion disk surrounding the mass-gaining star of {beta} Lyr A. A series of continuum visible and NIR spectro-interferometric observations by the NPOI, CHARA/MIRC and VEGA instruments covering the whole orbit of {beta} Lyr A acquired during a two-week campaign in 2013 were complemented with UBVR photometric observations acquired during a three-year monitoring of the system. We included NUV and FUV observations from OAO A-2, IUE, and Voyager satellites. All these observations were compared to a complex model of the system. It is based on the simple LTE radiative transfer code SHELLSPEC, which was substantially extended to compute all interferometric observables and to perform both global and local optimization of system parameters. Several shapes of the accretion disk were successfully tested - slab, wedge, and a disk with an exponential vertical profile - and the following properties were consistently found: the radius of the outer rim is 30.0+/-1.0R_{sun}_, the semithickness of the disk 6.5+/-1.0R_{sun}_, and the binary orbital inclination i=93.5+/-1.0deg. The temperature profile is a power-law or a steady-disk in case of the wedge geometry. The properties of the accretion disk indicate that it cannot be in a vertical hydrostatic equilibrium, which is in accord with the ongoing mass transfer. The hot spot was also detected in the continuum but is interpreted as a hotter part of the accretion disk illuminated by the donor. As a by-product, accurate kinematic and radiative properties of Lyr B were determined.
- ID:
- ivo://CDS.VizieR/J/A+A/312/879
- Title:
- Beta Lyr radial velocities and UBV data
- Short Name:
- J/A+A/312/879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A preliminary analysis of an extensive collection of interferometric, spectroscopic and photometric observations of the bright Be star {beta} Lyr lead to the following main conclusions: (1) The bulk of the H{alpha} and He I 6678 emission seems to originate in jets of material perpendicular to the orbital plane of the binary. The jets are associated with the more massive component of the binary (star 1) and probably emanate from the `hot spot' in the disk, i.e. the region of interaction of the gas stream flowing from the Roche-lobe filling B6-8II component (star 2) toward star 1. Some contribution to the emission also comes from a region located between the two stars (the gas stream and the `hot spot') and from the `pseudoatmosphere' of the accretion disk around star 1. (2) The 282-d cyclic variation of the light curve of {beta} Lyr is confirmed on the basis of 2852 homogenized V-band observations covering an interval of 36yrs. We find, however, that the amplitude and phase of these variations vary with the orbital phase: the long-term modulation of the light curve almost disappears near orbital phases 0.25P and 0.50P (elongation and secondary eclipse). (3) Pronounced line-profile variations of the H{alpha} and He I 6678 lines on a time scale shorter than one orbital period were clearly detected. They may be periodic, with a period near 4.70-4.75d, and this periodicity may be related to the 282-d change via the orbital period.
- 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.
- 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/542/A18
- Title:
- {beta}Pic Harps radial velocity data
- Short Name:
- J/A+A/542/A18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The {beta} Pictoris system with its debris disk and a massive giant planet orbiting at ~=9AU represents an ideal laboratory for studying giant planet formation and evolution as well as planet-disk interactions. {beta} Pic b can also help in testing brightness-mass relations at young ages. Other planets, yet undetected, may of course be present in the system. We aim at directly constraining the mass of {beta} Pic b and at searching for additional jovian planets on orbits closer than typically 2AU.
1788. beta Pic HARPS spectrum
- ID:
- ivo://CDS.VizieR/J/A+A/607/A25
- Title:
- beta Pic HARPS spectrum
- Short Name:
- J/A+A/607/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The young planetary system beta Pictoris is surrounded by a circumstellar disk of dust and gas. Because both dust and gas have a lifetime shorter than the system age, they need to be replenished continuously. The gas composition is partly known, but its location and its origin are still a puzzle. The gas source could be the exocomets (or so-called falling and evaporating bodies, FEBs), which are observed as transient features in absorption lines of refractory elements (Mg, Ca, and Fe) when they transit in front of the star at several tens of stellar radii. Nearly 1700 high-resolution spectra of beta Pictoris have been obtained from 2003 to 2015 using the HARPS spectrograph. In these spectra, the circumstellar disk is always detected as a stable component among the numerous variable absorption signatures of transiting exocomets. Summing all the 1700 spectra allowed us to reach a signal-to-noise ratio higher than 1000, which is an unprecedentedly high number for a beta Pictoris spectrum. It revealed many weak Fe I absorption lines of the circumstellar gas in more than ten excited states. These weak lines bring new information on the physical properties of the neutral iron gas in the circumstellar disk. The population of the first excited levels follows a Boltzmann distribution with a slope consistent with a gas temperature of about 1300K; this temperature corresponds to a distance to the star of ~38 R_star_ and implies a turbulence of ksi~0.8km/s.
1789. Beta Pictoris 1994-96
- ID:
- ivo://CDS.VizieR/J/MNRAS/304/733
- Title:
- Beta Pictoris 1994-96
- Short Name:
- J/MNRAS/304/733
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution spectroscopy of the variable CaII H & K absorptions in the star Beta Pictoris. 313 spectra were obtained on 53 nights between 1994 November and 1996 December in order to characterize the lines' behaviour and to test the Falling Evaporating Bodies (FEB) scenario. Near-continuous absorption activity was seen, including blue-shifted features, one of which rivalled the strength of that reported in 1997 June by Crawford et al. (1998MNRAS.294L..31C). Redshifted features at ~5-20km/s were present until the end of 1995 and are evocative of a year-long stream of infalling bodies with typically 4-5 objects in the line of sight. At higher velocities, features were shorter lived and generally broader and shallower. These correlations also apply to blue-shifted features. On 1995 June 9 we detected a probably narrow, short-lived feature at a redshift of ~130km/s. The FEB models predict that the strength of the H line may exceed the K line value as a body tracks across the stellar disc, but we have no convincing observation of this, though we did observe some events where the H & K absorptions evolved differently.
- ID:
- ivo://CDS.VizieR/J/MNRAS/489/574
- Title:
- beta Pictoris 1997 and 1998 spectra
- Short Name:
- J/MNRAS/489/574
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopy with resolution R~33000 of the circumstellar CaII H & K absorptions in the star beta Pictoris during 1997 and 1998. From 1997 April onwards, both lines were observed simultaneously. A total of 688 spectra were obtained on 95 nights in order to characterize the lines' behaviour. Near-continuous Falling Evaporating Body (FEB) variable absorption activity was seen, including additional strong, blue-shifted features besides the one on 1997 June 19-20 already reported by others. Temporal coverage is more even than in the HARPS spectra from 2004-11 that have been analysed for FEB orbital parameters via a model of FEB evaporation. Our observations likely encompass the 1997-98 Hill-sphere transit by beta Pic b, but we have found no clear signature of transiting material. Lower-velocity FEB absorptions tend to be deeper, narrower and longer lived, in confirmation of earlier studies. The ratio of line strengths for one absorption on 1998 November 27 is evocative of the variations expected for a single FEB making a transit perpendicular to the stellar rotation axis. Analysis with the evaporation model produces similar distributions of orbital parameters to those obtained from the HARPS observations, but when the derived orbital parameters are fed into a model based solely on gravitational dynamics of point masses, the predicted FEB accelerations do not agree with observed values. More sophisticated modelling is called for. There is no convincing intrinsic variation in the central circumstellar absorption such as might be expected if an HI ring is responsible for the confinement of circumstellar Ca^+^ ions. Our observations are available electronically for further analysis by others.
