Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/110/1774
- Title:
- K giants in Baade's window
- Short Name:
- J/AJ/110/1774
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first in a series of papers in which we analyze medium-resolution spectra of over 400 K and M giants in Baade's Window. Our sample was selected from the proper motion study of Spaenhauer et al. (1992AJ....103..297S). We have measured radial velocities for most of the sample, as well as line-strength indices on the system of Faber et al. (1985ApJS...57..711F). We analyze the random and systematic errors in velocities and line strengths, and show that the bright (V<16.0) stars in our sample are predominantly foreground disk stars along the line of sight toward Baade's Window. We find that most of the bulge K giants have stronger Mg absorption at a given color than do stars in the solar neighborhood. If the K giants in our sample are moderately old, we suggest that on average they may have [Mg/Fe] approximately +0.3, consistent with the results of recent high-resolution spectroscopy in Baade's Window.
- ID:
- ivo://CDS.VizieR/J/AJ/140/2025
- Title:
- KH 15D (V582 Mon) VI light curves
- Short Name:
- J/AJ/140/2025
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometry of the unique pre-main-sequence binary system KH 15D is presented, spanning the years 2005-2010. This system has exhibited photometric variations and eclipses over the last ~50 years that are attributed to the effect of a precessing circumbinary disk. Advancement of the occulting edge across the projection on the sky of the binary orbit has continued and the photospheres of both stars are now completely obscured at all times. The system has thus transitioned to a state in which it should be visible only by scattered light, and yet it continues to show a periodic variation on the orbital cycle with an amplitude exceeding 2mag.
- ID:
- ivo://CDS.VizieR/J/ApJ/540/236
- Title:
- KH photometry of Orion Nebula Cluster
- Short Name:
- J/ApJ/540/236
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a 0.5"-0.9" FWHM imaging survey at K (2.2{mu}m) and H (1.6{mu}m) covering ~ 5.1'x5.1' centered on {theta}^1^C Ori, the most massive star in the Orion Nebula Cluster (ONC). At the age and distance of this cluster, and in the absence of extinction, the hydrogen-burning limit (0.08M_{sun}_) occurs at K~13.5mag, while an object of mass 0.02M_{sun}_ has K~16.2mag. Our photometry is complete for source detection at the 7{sigma} level to K~17.5mag and thus is sensitive to objects as low-mass as 0.02M_{sun}_ seen through visual extinction values as high as 10mag. We use the observed magnitudes, colors, and star counts to constrain the shape of the inner ONC stellar mass function across the hydrogen-burning limit. After determining the stellar age and near-infrared excess properties of the optically visible stars in this same inner ONC region, we present a new technique that incorporates these distributions when extracting the mass function from the observed density of stars in the K-(H-K) diagram. We find that our data are inconsistent with a mass function that rises across the stellar/substellar boundary. Instead, we find that the most likely form of the inner ONC mass function is one that rises to a peak around 0.15M_{sun}_, and then declines across the hydrogen-burning limit with slope N(log M){prop.to}M^0.57^. We emphasize that our conclusions apply to the inner 0.71pc x 0.71pc of the ONC only; they may not apply to the ONC as a whole where some evidence for general mass segregation has been found.
- ID:
- ivo://CDS.VizieR/J/ApJ/853/77
- Title:
- KIC 8462852 ASAS V-band long-term variability
- Short Name:
- J/ApJ/853/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ~800 days of photometric monitoring of Boyajian's Star (KIC8462852) from the All-Sky Automated Survey for Supernovae (ASAS-SN) and ~4000d of monitoring from the All Sky Automated Survey (ASAS). We show that from 2015 to the present the brightness of Boyajian's Star has steadily decreased at a rate of 6.3+/-1.4mmag/yr, such that the star is now 1.5% fainter than it was in 2015 February. Moreover, the longer time baseline afforded by ASAS suggests that Boyajian's Star has also undergone two brightening episodes in the past 11 years, rather than only exhibiting a monotonic decline. We analyze a sample of ~1000 comparison stars of similar brightness located in the same ASAS-SN field and demonstrate that the recent fading is significant at >=99.4% confidence. The 2015-2017 dimming rate is consistent with that measured with Kepler data for the time period from 2009 to 2013. This long-term variability is difficult to explain with any of the physical models for the star's behavior proposed to date.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/189
- Title:
- KIC 11401845 eclipse timings
- Short Name:
- J/ApJ/835/189
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the Kepler photometry of KIC 11401845 displaying multiperiodic pulsations, superimposed on binary effects. Light-curve synthesis shows that the binary star is a short-period detached system with a very low mass ratio of q=0.070 and filling factors of F_1_=45% and F_2_=99%. Multiple-frequency analyses were applied to the light residuals after subtracting the synthetic eclipsing curve from the observed data. We detected 23 frequencies with signal-to-noise ratios larger than 4.0, of which the orbital harmonics (f_4_, f_6_, f_9_, f_15_) in the low-frequency domain may originate from tidally excited modes. For the high frequencies of 13.7-23.8day^-1^, the period ratios and pulsation constants are in the ranges of P_pul_/P_orb_=0.020-0.034 and Q=0.018-0.031days, respectively. These values and the position on the Hertzsprung-Russell diagram demonstrate that the primary component is a {delta} Sct pulsating star. We examined the eclipse timing variation of KIC 11401845 from the pulsation-subtracted data and found a delay of 56+/-17s in the arrival times of the secondary eclipses relative to the primary eclipses. A possible explanation of the time shift may be some combination of a light-travel-time delay of about 34s and a very small eccentricity of e.cos{omega}<0.0002. This result represents the first measurement of the Romer delay in noncompact binaries.
3317. KIC 9832227 light curves
- ID:
- ivo://CDS.VizieR/J/A+A/631/A126
- Title:
- KIC 9832227 light curves
- Short Name:
- J/A+A/631/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We revisit the issue of period variation of the recently claimed red nova precursor candidate KIC 9832227. By using the data gathered during the main mission of the Kepler satellite, and data collected by ground-based wide-field surveys and other monitoring programs (such as ASAS-SN), we find that the currently available timing data strongly support a model consisting of the known W UMa binary and a distant low-mass companion with an orbital period of ~13.5 years. The period of the W UMa component exhibits a linear period decrease at a rate of (1.10+/-0.05)x10^-6^ days per year, within the range of many other similar systems. This rate of decrease is several orders of magnitude lower than that of V1309 Sco, the first (and so far the only) well-established binary precursor of a nova observed a few years before the outburst. The high-fidelity fit of the timing data and the conformity of the derived minimum mass of (0.38+/-0.02)M_{sun}_ of the outer companion from these data with the limit posed by the spectroscopic non-detection of this component are in agreement with the suggested hierarchical nature of this system.
- ID:
- ivo://CDS.VizieR/J/ApJ/847/131
- Title:
- KIC 8462852 one-yr obs. from UV to MIR
- Short Name:
- J/ApJ/847/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To test alternative hypotheses for the behavior of KIC 8462852, we obtained measurements of the star over a wide wavelength range from the UV to the mid- infrared from 2015 October through 2016 December, using Swift, Spitzer and AstroLAB IRIS. The star faded in a manner similar to the long-term fading seen in Kepler data about 1400 days previously. The dimming rate for the entire period reported is 22.1+/-9.7mmag/yr in the Swift wavebands, with amounts of 21.0+/-4.5mmag in the ground-based B measurements, 14.0+/-4.5mmag in V, and 13.0+/-4.5 in R, and a rate of 5.0+/-1.2mmag/yr averaged over the two warm Spitzer bands. Although the dimming is small, it is seen at >~3{sigma} by three different observatories operating from the UV to the IR. The presence of long-term secular dimming means that previous spectral energy distribution models of the star based on photometric measurements taken years apart may not be accurate. We find that stellar models with Teff=7000-7100K and A_V_~0.73 best fit the Swift data from UV to optical. These models also show no excess in the near-simultaneous Spitzer photometry at 3.6 and 4.5{mu}m, although a longer wavelength excess from a substantial debris disk is still possible (e.g., as around Fomalhaut). The wavelength dependence of the fading favors a relatively neutral color (i.e., R_V_>~5, but not flat across all the bands) compared with the extinction law for the general interstellar medium (R_V_=3.1), suggesting that the dimming arises from circumstellar material.
- ID:
- ivo://CDS.VizieR/J/AJ/142/112
- Title:
- KIC photometric calibration
- Short Name:
- J/AJ/142/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the photometric calibration and stellar classification methods used by the Stellar Classification Project to produce the Kepler Input Catalog (KIC). The KIC is a catalog containing photometric and physical data for sources in the Kepler mission field of view; it is used by the mission to select optimal targets. Four of the visible-light (g, r, i, z) magnitudes used in the KIC are tied to Sloan Digital Sky Survey magnitudes; the fifth (D51) is an AB magnitude calibrated to be consistent with Castelli & Kurucz (CK) model atmosphere fluxes. We derived atmospheric extinction corrections from hourly observations of secondary standard fields within the Kepler field of view.
- ID:
- ivo://CDS.VizieR/J/ApJ/831/11
- Title:
- KIC 9777062 RVs & asteroseismology in NGC6811
- Short Name:
- J/ApJ/831/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of an eccentric, partially eclipsing long-period (P=19.23 days) binary system KIC 9777062 that contains main-sequence stars near the turnoff of the intermediate-age open cluster NGC 6811. The primary is a metal-lined Am star with a possible convective blueshift to its radial velocities, and one star (probably the secondary) is likely to be a {gamma} Dor pulsator. The component masses are 1.603+/-0.006(stat.)+/-0.016(sys.) and 1.419+/-0.003+/-0.008M_{sun}_, and the radii are 1.744+/-0.004+/-0.002 and 1.544+/-0.002+/-0.002R_{sun}_. The isochrone ages of the stars are mildly inconsistent: the age from the mass-radius combination for the primary (1.05+/-0.05+/-0.09Gyr, where the last quote was systematic uncertainty from models and metallicity) is smaller than that from the secondary (1.21+/-0.05+/-0.15Gyr) and is consistent with the inference from the color-magnitude diagram (1.00+/-0.05Gyr). We have improved the measurements of the asteroseismic parameters {Delta}{nu} and {nu}_max_ for helium-burning stars in the cluster. The masses of the stars appear to be larger (or alternately, the radii appear to be smaller) than predicted from isochrones using the ages derived from the eclipsing stars. The majority of stars near the cluster turnoff are pulsating stars: we identify a sample of 28 {delta} Sct, 15 {gamma} Dor, and 5 hybrid types. We used the period-luminosity relation for high-amplitude {delta} Sct stars to fit the ensemble of the strongest frequencies for the cluster members, finding (m-M)_V_=10.37+/-0.03. This is larger than most previous determinations, but smaller than values derived from the eclipsing binary (10.47+/-0.05).
