- ID:
- ivo://CDS.VizieR/J/AJ/162/75
- Title:
- Speckle observations TESS exoplanet host stars. II.
- Short Name:
- J/AJ/162/75
- Date:
- 18 Mar 2022 09:30:45
- Publisher:
- CDS
- Description:
- We present high-angular-resolution imaging observations of 517 host stars of TESS exoplanet candidates using the 'Alopeke and Zorro speckle cameras at Gemini North and South. The sample consists mainly of bright F, G, K stars at distances of less than 500pc. Our speckle observations span angular resolutions of ~20mas out to 1.2", yielding spatial resolutions of <10-500au for most stars, and our contrast limits can detect companion stars 5-9mag fainter than the primary at optical wavelengths. We detect 102 close stellar companions and determine the separation, magnitude difference, mass ratio, and estimated orbital period for each system. Our observations of exoplanet host star binaries reveal that they have wider separations than field binaries, with a mean orbital semimajor axis near 100 au. Other imaging studies have suggested this dearth of very closely separated binaries in systems which host exoplanets, but incompleteness at small separations makes it difficult to disentangle unobserved companions from a true lack of companions. With our improved angular resolution and sensitivity, we confirm that this lack of close exoplanet host binaries is indeed real. We also search for a correlation between planetary orbital radii versus binary star separation; but, given the very short orbital periods of the TESS planets, we do not find any clear trend. We do note that in exoplanet systems containing binary host stars, there is an observational bias against detecting Earth-size planet transits due to transit depth dilution caused by the companion star.
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- ID:
- ivo://CDS.VizieR/J/AJ/161/221
- Title:
- Photometry & spectroscopy of 4 binaries stars
- Short Name:
- J/AJ/161/221
- Date:
- 16 Mar 2022 11:53:19
- Publisher:
- CDS
- Description:
- We present the photometric and spectroscopic analysis of four W-UMa binaries J015829.5+260333 (hereinafter as J0158), J030505.1+293443 (hereinafter as J0305), J102211.7+310022 (hereinafter as J1022), and KW-Psc. The VRcIc band photometric observations are carried out with the 1.3m Devasthal Fast Optical Telescope (DFOT). For low-resolution spectroscopy, we used the 2m Himalayan Chandra Telescope (HCT) as well as the archival data from the 4m LAMOST survey. The systems J0158 and J0305 show a period increase rate of 5.26({+/-}1.72)x10^-7^days/yr and 1.78({+/-}1.52)x10^-6^days/yr, respectively. The period of J1022 is found to be decreasing with a rate of 4.22({+/-}1.67)x10^-6^days/yr. The period analysis of KW-Psc displays no change in its period. The PHOEBE package is used for the light-curve modeling and basic parameters are evaluated with the help of the GAIA parallax. The asymmetry of light curves is explained with the assumption of cool spots at specific positions on one of the components of the system. On the basis of temperatures, mass ratios, fill-out factors, and periods, the system J1022 is identified as a W-subtype system while the others show some mixed properties. To probe the chromospheric activities in these W-UMa binaries, their spectra are compared with the known inactive stars' spectra. The comparison shows emission in H{alpha}, H{beta}, and CaII. To understand the evolutionary status of these systems, the components are plotted in mass-radius and mass-luminosity planes with other well characterized binary systems. The secondary components of all the systems are away from ZAMS, which indicates that the secondary is more evolved than the primary component.
- ID:
- ivo://CDS.VizieR/J/ApJ/885/100
- Title:
- Evolu. star mass-metallicity relation. II.
- Short Name:
- J/ApJ/885/100
- Date:
- 16 Mar 2022 11:50:55
- Publisher:
- CDS
- Description:
- We present the stellar mass-[Fe/H] and mass-[Mg/H] relation of quiescent galaxies in two galaxy clusters at z~0.39 and z~0.54. We derive the age, [Fe/H], and [Mg/Fe] for each individual galaxy using a full-spectrum fitting technique. By comparing with the relations for z~0 Sloan Digital Sky Survey galaxies, we confirm our previous finding that the mass-[Fe/H] relation evolves with redshift. The mass-[Fe/H] relation at higher redshift has lower normalization and possibly steeper slope. However, based on our sample, the mass-[Mg/H] relation does not evolve over the observed redshift range. We use a simple analytic chemical evolution model to constrain the average outflow that these galaxies experience over their lifetime, via the calculation of mass-loading factor. We find that the average mass-loading factor {eta} is a power-law function of galaxy stellar mass, {eta}{prop}M*^-0.21{+/-}0.09^. The measured mass-loading factors are consistent with the results of other observational methods for outflow measurements and with the predictions where outflow is caused by star formation feedback in turbulent disks.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/161
- Title:
- 500days of ASASSN-18pg multiwavelength obs.
- Short Name:
- J/ApJ/898/161
- Date:
- 16 Mar 2022 00:55:51
- Publisher:
- CDS
- Description:
- We present nearly 500 days of observations of the tidal disruption event (TDE) ASASSN-18pg, spanning from 54 days before peak light to 441 days after peak light. Our data set includes X-ray, UV, and optical photometry, optical spectroscopy, radio observations, and the first published spectropolarimetric observations of a TDE. ASASSN-18pg was discovered on 2018 July 11 by the All-Sky Automated Survey for Supernovae (ASAS-SN) at a distance of d=78.6Mpc; with a peak UV magnitude of m~14, it is both one of the nearest and brightest TDEs discovered to-date. The photometric data allow us to track both the rise to peak and the long-term evolution of the TDE. ASASSN-18pg peaked at a luminosity of L~2.4x10^44^erg/s, and its late-time evolution is shallower than a flux {propto}t^-5/3^ power-law model, similar to what has been seen in other TDEs. ASASSN-18pg exhibited Balmer lines and spectroscopic features consistent with Bowen fluorescence prior to peak, which remained detectable for roughly 225days after peak. Analysis of the two-component H{alpha} profile indicates that, if they are the result of reprocessing of emission from the accretion disk, the different spectroscopic lines may be coming from regions between ~10 and ~60 lt-days from the black hole. No X-ray emission is detected from the TDE, and there is no evidence of a jet or strong outflow detected in the radio. Our spectropolarimetric observations indicate that the projected emission region is likely not significantly aspherical, with the projected emission region having an axis ratio of >~0.65.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/56
- Title:
- UVOT, ZTF gri LCs and spectra of the SN Ia 2019yvq
- Short Name:
- J/ApJ/898/56
- Date:
- 16 Mar 2022 00:53:53
- Publisher:
- CDS
- Description:
- Early observations of Type Ia supernovae (SNe Ia) provide essential clues for understanding the progenitor system that gave rise to the terminal thermonuclear explosion. We present exquisite observations of SN 2019yvq, the second observed SN Ia, after iPTF 14atg, to display an early flash of emission in the ultraviolet (UV) and optical. Our analysis finds that SN 2019yvq was unusual, even when ignoring the initial flash, in that it was moderately underluminous for an SN Ia (M_g_~-18.5mag at peak) yet featured very high absorption velocities (v~15000km/s for SiII{lambda}6355 at peak). We find that many of the observational features of SN 2019yvq, aside from the flash, can be explained if the explosive yield of radioactive 56Ni is relatively low (we measure M_56Ni_=0.31+/-0.05M_{sun}_) and it and other iron-group elements are concentrated in the innermost layers of the ejecta. To explain both the UV/optical flash and peak properties of SN 2019yvq we consider four different models: interaction between the SN ejecta and a nondegenerate companion, extended clumps of ^56^Ni in the outer ejecta, a double-detonation explosion, and the violent merger of two white dwarfs. Each of these models has shortcomings when compared to the observations; it is clear additional tuning is required to better match SN 2019yvq. In closing, we predict that the nebular spectra of SN 2019yvq will feature either H or He emission, if the ejecta collided with a companion, strong [CaII] emission, if it was a double detonation, or narrow [OI] emission, if it was due to a violent merger.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/180
- Title:
- Multiband photometry of microlensing event Kojima-1
- Short Name:
- J/ApJ/897/180
- Date:
- 16 Mar 2022 00:48:14
- Publisher:
- CDS
- Description:
- We report the lens mass and distance measurements of the nearby microlensing event TCPJ05074264+2447555 (Kojima-1). We measure the microlens parallax vector {pi}_E_ using Spitzer and ground-based light curves with constraints on the direction of lens-source relative proper motion derived from Very Large Telescope Interferometer (VLTI) GRAVITY observations. Combining this {pi}_E_ determination with the angular Einstein radius {theta}_E_ measured by VLTI-GRAVITY observations, we find that the lens is a star with mass M_L_=0.495{+/-}0.063M{odot} at a distance DL=429{+/-}21pc. We find that the blended light basically all comes from the lens. The lens-source proper motion is {mu}_rel,hel_=26.55{+/-}0.36mas/yr, so with currently available adaptive-optics instruments, the lens and source can be resolved in 2021. This is the first microlensing event whose lens mass is unambiguously measured by interferometry+satellite-parallax observations, which opens a new window for mass measurements of isolated objects such as stellar-mass black holes.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/159
- Title:
- Type Ia supernova SN 2019ein UBVgri photometry
- Short Name:
- J/ApJ/897/159
- Date:
- 16 Mar 2022 00:28:33
- Publisher:
- CDS
- Description:
- We present multiwavelength photometric and spectroscopic observations of SN 2019ein, a high-velocity Type Ia supernova (SNIa) discovered in the nearby galaxy NGC5353 with a two-day nondetection limit. SN 2019ein exhibited some of the highest measured expansion velocities of any SNIa, with a SiII absorption minimum blueshifted by 24000km/s at 14days before peak brightness. More unusually, we observed the emission components of the PCygni profiles to be blueshifted upward of 10000km/s before B-band maximum light. This blueshift, among the highest in a sample of 28 other SNeIa, is greatest at our earliest spectroscopic epoch and subsequently decreases toward maximum light. We discuss possible progenitor systems and explosion mechanisms that could explain these extreme absorption and emission velocities. Radio observations beginning 14days before B-band maximum light yield nondetections at the position of SN2019ein, which rules out symbiotic progenitor systems, most models of fast optically thick accretion winds, and optically thin shells of mass<~10^-6^M{odot} at radii <100au. Comparing our spectra to models and observations of other high-velocity SNeIa, we find that SN2019ein is well fit by a delayed-detonation explosion. We propose that the high emission velocities may be the result of abundance enhancements due to ejecta mixing in an asymmetric explosion, or optical depth effects in the photosphere of the ejecta at early times. These findings may provide evidence for common explosion mechanisms and ejecta geometries among high-velocity SNeIa.
- ID:
- ivo://CDS.VizieR/J/ApJ/895/32
- Title:
- Zwicky Transient Facility BTS. I.
- Short Name:
- J/ApJ/895/32
- Date:
- 16 Mar 2022 00:25:08
- Publisher:
- CDS
- Description:
- The Zwicky Transient Facility (ZTF) is performing a three-day cadence survey of the visible northern sky (~3{pi}) with newly found transient candidates announced via public alerts. The ZTF Bright Transient Survey (BTS) is a large spectroscopic campaign to complement the photometric survey. BTS endeavors to spectroscopically classify all extragalactic transients with m_peak_<~18.5mag in either the g_ZTF_ or r_ZTF_ filters, and publicly announce said classifications. BTS discoveries are predominantly supernovae (SNe), making this the largest flux-limited SN survey to date. Here we present a catalog of 761 SNe, classified during the first nine months of ZTF (2018 April 1-2018 December 31). We report BTS SN redshifts from SN template matching and spectroscopic host-galaxy redshifts when available. We analyze the redshift completeness of local galaxy catalogs, the redshift completeness fraction (RCF; the ratio of SN host galaxies with known spectroscopic redshift prior to SN discovery to the total number of SN hosts). Of the 512 host galaxies with SNe Ia, 227 had previously known spectroscopic redshifts, yielding an RCF estimate of 44%{+/-}4%. The RCF decreases with increasing distance and decreasing galaxy luminosity (for z<0.05, or ~200Mpc, RCF~0.6). Prospects for dramatically increasing the RCF are limited to new multifiber spectroscopic instruments or wide-field narrowband surveys. Existing galaxy redshift catalogs are only ~50% complete at r~16.9mag. Pushing this limit several magnitudes deeper will pay huge dividends when searching for electromagnetic counterparts to gravitational wave events or sources of ultra-high-energy cosmic rays or neutrinos.
- ID:
- ivo://CDS.VizieR/J/AJ/162/17
- Title:
- KMTNet, MOA and OGLE light curve of KMT-2019-BLG-0371
- Short Name:
- J/AJ/162/17
- Date:
- 16 Mar 2022 00:13:06
- Publisher:
- CDS
- Description:
- We show that the perturbation at the peak of the light curve of microlensing event KMT-2019-BLG-0371 is explained by a model with a mass ratio between the host star and planet of q~0.08. Due to the short event duration (t_E_~6.5days), the secondary object in this system could potentially be a massive giant planet. A Bayesian analysis shows that the system most likely consists of a host star with a mass M_h_=0.09_-0.05_^+0.14^Msun and a massive giant planet with a mass M_p_=7.70_-3.90_^+11.34^M_Jup_. However, the interpretation of the secondary as a planet (i.e., as having M_p_<13M_Jup_) rests entirely on the Bayesian analysis. Motivated by this event, we conduct an investigation to determine which constraints meaningfully affect Bayesian analyses for microlensing events. We find that the masses inferred from such a Bayesian analysis are determined almost entirely by the measured value of {theta}_E_ and are relatively insensitive to other factors such as the direction of the event (l, b), the lens-source relative proper motion {mu}_rel_, or the specific Galactic model prior.
- ID:
- ivo://CDS.VizieR/J/AJ/161/292
- Title:
- BVRI photometry of pre-W UMA binary V642 Virginis
- Short Name:
- J/AJ/161/292
- Date:
- 16 Mar 2022 00:08:32
- Publisher:
- CDS
- Description:
- V642Vir is a polar spotted, well-detached, UV Leo-type, low-mass, pre-WUMa (T1~4250K, ~K6V) eclipsing binary. It was observed in 2020 April, May, and June at the Dark Sky Observatory in North Carolina, USA with the 0.81m reflector of Appalachian State University. A total of 88 timings were used in our 22-year period study which included 12 Transiting Exoplanet Survey Satellite (TESS) timings. The O-C plots show a low-amplitude oscillation of residuals that points to the existence of an orbiting third body, a dwarf of minimum mass, 0.15M{sun} in an eccentric orbit (e=0.41), with an orbital period of 20.07yr. The odd light curves of V642 Virginis indicate that it has polar spots similar to UV Leo and the recently published V1023Per. Its present large polar spot region indicates that it must have a strong magnetic field and that it is synchronously rotating. The BVR_c_I_c_ simultaneous Wilson-Devinney Program solution gives a detached binary (primary and secondary components are underfilling their respective Roche Lobes, with 76% and 78% fill outs respectively). The cool spot region models near the pole of the primary component (centered at 10{deg} colatitude) and is angled toward the secondary component. Its large radius (68{deg}) and T-fact (T_spot_/T_surface_=0.69) also attest to the conclusion of the strength of the magnetic field. The small {Delta}T in the components (~318K) and mass ratio near unity (0.9542{+/-}0.0005) show that the stars are similar in spectral type (secondary ~K9V). The inclination is high, ~86.87{+/-}0.04{deg}, yet there is no time of constant light due to the two stars essentially equal radii.