- ID:
- ivo://CDS.VizieR/J/other/RAA/9.1035
- Title:
- RV light curves of 1RXS J201607.0+251645
- Short Name:
- J/other/RAA/9.10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 1RXS J201607.0+251645 is identified as an eclipsing binary. We present preliminary observations in the V band with the 0.6-m telescope for three years and extensive observations in the V and R bands with the 0.8-m telescope for six nights, respectively. The light curve of the system is EB type. Five light minimum times were obtained and the orbital period of 0.388058d(+/-0.00044d) is determined.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/123/3154
- Title:
- RV light curves of variable stars in Leo A
- Short Name:
- J/AJ/123/3154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for short-period variable stars in Leo A. We have found 92 candidate variables, including eight candidate RR Lyrae stars. From the RR Lyrae stars, we measure a distance modulus of (m-M)0=24.51+/-0.12, or 0.80+/-0.04Mpc. This discovery of RR Lyrae stars confirms for the first time the presence of an ancient (older than ~11Gyr) population in Leo A, accounting for at least 0.1% of the galaxy's V luminosity. We have also discovered a halo of old (more than ~2Gyr) stars surrounding Leo A, with a scale length roughly 50% larger than that of the dominant young population. We also report the discovery of a large population of Cepheids in Leo A. The median absolute magnitude of our Cepheid sample is M_V_=-1.1, fainter than 96% of SMC and 99% of LMC Cepheids. Their periods are also unusual, with three Cepheids that are deduced to be pulsating in the fundamental mode having periods of under 1 day. Upon examination, these characteristics of the Leo A Cepheid population appear to be a natural extension of the classical Cepheid period-luminosity relations to low metallicity, rather than being indicative of a large population of "anomalous" Cepheids. We demonstrate that the periods and luminosities are consistent with the expected values of low-metallicity blue helium-burning stars (BHeB's), which populate the instability strip at lower luminosities than do higher metallicity BHeB's. Observations of Leo A were obtained at the WIYN 3.5 m telescope on the nights of 20-22 December 2000, using the MIMO camera.
- ID:
- ivo://CDS.VizieR/J/AN/338/671
- Title:
- RV measurements of eight spectroscopic binaries
- Short Name:
- J/AN/338/671
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since early 2015 a new radial velocity monitoring campaign is going on at the University Observatory Jena. The aim of this project is to obtain current radial velocity measurements of selected single-lined spectroscopic binary systems, to re-determine and/or constrain their orbital solutions.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1337
- Title:
- RV of 111 Galactic halo stars in Virgo
- Short Name:
- J/AJ/140/1337
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multi-slit radial velocity measurements for 111 stars in the direction of the Virgo Stellar Stream (VSS). The stars were photometrically selected to be probable main-sequence stars in the Galactic halo. When compared with the radial velocity distribution expected for the halo of the Milky Way, as well as the distribution seen in a control field, we observe a significant excess of negative velocity stars in the field, which can likely be attributed to the presence of a stellar stream.
- ID:
- ivo://CDS.VizieR/J/AJ/121/841
- Title:
- RV photometry of Draco dwarf spheroidal galaxy
- Short Name:
- J/AJ/121/841
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report R- and V-band photometry derived from CCD imaging for objects in nine fields in and around the Draco dwarf spheroidal galaxy. The most distant fields are about 1.3{deg} from the center. We use these data to search for Draco stars outside of its measured tidal boundary. The search involves three methods: (1) plotting color-magnitude diagrams for individual fields, for sections of fields, and for combined fields and sections - a colour-magnitude diagram can reveal a population of Draco stars by the presence of the expected principal sequences; (2) measuring field-to-field fluctuations in the surface density of objects located near the Draco principal sequences in the color-magnitude diagram; (3) measuring intrafield fluctuations in the surface density of those objects. We find evidence for the presence of Draco stars immediately beyond the measured tidal boundary of Draco and place an upper limit on the number of such stars in more distant fields that lie close to the extension of its major axis. The best evidence is the presence of the Draco principal sequences in the color-magnitude diagram for some combined fields and sections of fields. The measurements of the field-to-field fluctuations in the stellar surface density confirm this result.
- ID:
- ivo://CDS.VizieR/J/AJ/123/2511
- Title:
- RV photometry of Draco dwarf spheroidal galaxy
- Short Name:
- J/AJ/123/2511
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This article studies the structure of the Draco dwarf spheroidal galaxy, with an emphasis on the question of whether the spatial distribution of its stars has been affected by the tidal interaction with the Milky Way, using R- and V-band CCD photometry for 11 fields that are located in and around the Draco galaxy. 9 fields are in common with Piatek et al. (J/AJ/121/841); two additional fields, N1 and S1, are adjacent to the central C0 field studied by Piatek et al. in the north and south dire ctions, respectively, and extend beyond the tidal boundary along the minor axis. hese additional fields were imaged with the KPNO 0.9 m telescope using the 2048x2048 T2KA CCD chip. The article reports coordinates for the center, a position angle of the major axis, and the ellipticity. It also reports the results of searches for asymmetries in the structure of Draco. These results and searches for a "break" in the radial profile and for the presence of principal sequences of Draco in a color-magnitude diagram for regions more than 50' from the center yield no evidence that tidal forces from the Milky Way have affected the structure of Draco.
- ID:
- ivo://CDS.VizieR/J/ApJ/769/107
- Title:
- RVs and [Fe/H] of star members of NGC 6388
- Short Name:
- J/ApJ/769/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By combining high spatial resolution and wide-field spectroscopy performed, respectively, with SINFONI and FLAMES at the ESO/VLT we measured the radial velocities of more than 600 stars in the direction of NGC 6388, a Galactic globular cluster which is suspected to host an intermediate-mass black hole. Approximately 55% of the observed targets turned out to be cluster members. The cluster velocity dispersion has been derived from the radial velocity of individual stars: 52 measurements in the innermost 2", and 276 stars located between 18" and 600". The velocity dispersion profile shows a central value of ~13km/s, a flat behavior out to ~60" and a decreasing trend outward. The comparison with spherical and isotropic models shows that the observed density and velocity dispersion profiles are inconsistent with the presence of a central black hole more massive than ~2000M_{sun}_. These findings are at odds with recent results obtained from integrated light spectra, showing a velocity dispersion profile with a steep central cusp of 23-25km/s at r<2" and suggesting the presence of a black hole with a mass of ~1.7x10^4^M_{sun}_. We also found some evidence of systemic rotation with amplitude A_rot_~8km/s in the innermost 2" (0.13pc), decreasing to A_rot_=3.2km/s at 18"<r<160".
- ID:
- ivo://CDS.VizieR/J/AJ/157/55
- Title:
- RVs and light curves for HATS-60-HATS-69
- Short Name:
- J/AJ/157/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 10 transiting extrasolar planets by the HATSouth survey. The planets range in mass from the super-Neptune HATS-62b, with M_p_<0.179 M_J_, to the super-Jupiter HATS-66b, with M_p_=5.33 M_J_, and in size from the Saturn HATS-69b, with R_p_=0.94 R_J_, to the inflated Jupiter HATS-67b, with R_p_=1.69 R_J_. The planets have orbital periods between 1.6092 days (HATS-67b) and 7.8180 days (HATS-61b). The hosts are dwarf stars with masses ranging from 0.89 M_{sun}_ (HATS-69) to 1.56 M_{sun}_ (HATS-64) and have apparent magnitudes between V=12.276+/-0.020 mag (HATS-68) and V=14.095+/-0.030 mag (HATS-66). The super-Neptune HATS-62b is the least massive planet discovered to date with a radius larger than Jupiter. Based largely on the Gaia DR2 distances and broadband photometry, we identify three systems (HATS-62, HATS-64, and HATS-65) as having possible unresolved binary star companions. We discuss in detail our methods for incorporating the Gaia DR2 observations into our modeling of the system parameters and into our blend analysis procedures.
- ID:
- ivo://CDS.VizieR/J/AJ/159/145
- Title:
- RVs and opt. photometry of the host star TOI-677
- Short Name:
- J/AJ/159/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of TOI-677b, first identified as a candidate in light curves obtained within Sectors 9 and 10 of the Transiting Exoplanet Survey Satellite (TESS) mission and confirmed with radial velocities. TOI-677b has a mass of M_p_=1.236_-0.067_^+0.069^M_J_, a radius of R_P_=1.170{+/-}0.03R_J_, and orbits its bright host star (V=9.8mag) with an orbital period of 11.23660{+/-}0.00011d, on an eccentric orbit with e=0.435{+/-}0.024. The host star has a mass of M_*_=1.181{+/-}0.058M_{sun}_, a radius of R_*_=1.28_-0.03_^+0.03^R_{sun}_, an age of 2.92_-0.73_^+0.80^Gyr and solar metallicity, properties consistent with a main-sequence late-F star with T_eff_=6295{+/-}77K. We find evidence in the radial velocity measurements of a secondary long-term signal, which could be due to an outer companion. The TOI-677b system is a well-suited target for Rossiter-Mclaughlin observations that can constrain migration mechanisms of close-in giant planets.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/177
- Title:
- RVs and R-band obs. of the EB* V541 Cyg
- Short Name:
- J/ApJ/836/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new spectroscopic and photometric observations of the main-sequence, detached, eccentric, double-lined eclipsing binary V541Cyg (P=15.34d, e=0.468). Using these observations together with existing measurements, we determine the component masses and radii to better than 1% precision: M_1_=2.335_-0.013_^+0.017^M_{sun}_, M_2_=2.260_-0.013_^+0.016^M_{sun}_, R_1_=1.859_-0.009_^+0.012^R_{sun}_, and R_2_=1.808_-0.013_^+0.015^R_{sun}_. The nearly identical B9.5 stars have estimated effective temperatures of 10650+/-200K and 10350+/-200K. A comparison of these properties with current stellar evolution models shows excellent agreement at an age of about 190Myr and [Fe/H]~-0.18. Both components are found to be rotating at the pseudo-synchronous rate. The system displays a slow periastron advance that is dominated by general relativity (GR), and has previously been claimed to be slower than predicted by theory. Our new measurement, dot{omega}=0.859_-0.017_^+0.042^deg/century, has an 88% contribution from GR and agrees with the expected rate within the uncertainties. We also clarify the use of the gravity darkening coefficients in the light-curve fitting Eclipsing Binary Orbit Program (EBOP), a version of which we use here.
