- ID:
- ivo://CDS.VizieR/J/AJ/159/267
- Title:
- Observations & radial velocity of HATS-71b
- Short Name:
- J/AJ/159/267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HATS-71b, a transiting gas giant planet on a P=3.7955day orbit around a G=15.35mag M3 dwarf star. HATS-71 is the coolest M dwarf star known to host a hot Jupiter. The loss of light during transits is 4.7%, more than in any other confirmed transiting planet system. The planet was identified as a candidate by the ground-based HATSouth transit survey. It was confirmed using ground-based photometry, spectroscopy, and imaging, as well as space-based photometry from the NASA Transiting Exoplanet Survey Satellite mission (TIC234523599). Combining all of these data, and utilizing Gaia DR2, we find that the planet has a radius of 1.024{+/-}0.018R_J_ and mass of 0.37{+/-}0.24M_J_ (95% confidence upper limit of <0.80M_J_), while the star has a mass of 0.4861{+/-}0.0060M_{sun}_ and a radius of 0.4783{+/-}0.0060R_{sun}_.
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- ID:
- ivo://CDS.VizieR/J/AcA/63/379
- Title:
- OGLE-III variable stars in Galactic disk area
- Short Name:
- J/AcA/63/379
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for pulsating stars in the 7.12deg^2^ OGLE-III Galactic disk area in the direction tangent to the Centaurus Arm. We report the identification of 20 Classical Cepheids, 45 RR Lyr type stars, 31 Long-Period Variables, such as Miras and Semi-Regular Variables, one pulsating white dwarf, and 58 very likely {delta} Sct type stars. Based on asteroseismic models constructed for one quadruple-mode and six triple-mode {delta} Sct type pulsators, we estimated masses, metallicities, ages, and distance moduli to these objects. The modeled stars have masses in the range 0.9-2.5M_{sun}_ and are located at distances between 2.5kpc and 6.2kpc. Two triple-mode and one double-mode pulsators seem to be Population II stars of the SX Phe type, probably from the Galactic halo. Our sample also includes candidates for Type II Cepheids and unclassified short-period (P<0.23d) multi-mode stars which could be either {delta}Sct or {beta}Cep type stars. One of the detected variables is a very likely {delta} Sct star with an exceptionally high peak-to-peak I-band amplitude of 0.35mag at the very short period of 0.0196d. All reported pulsating variable stars but one object are new discoveries. They are included in the OGLE-III Catalog of Variable Stars. Finally, we introduce the on-going OGLE-IV Galactic Disk Survey, which covers more than half of the Galactic plane. For the purposes of future works on the spiral structure and star formation history of the Milky Way, we have already compiled a list of known Galactic Classical Cepheids.
- ID:
- ivo://CDS.VizieR/J/AJ/144/16
- Title:
- Optical and HI properties of galaxies in voids
- Short Name:
- J/AJ/144/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carefully selected a sample of 60 galaxies that reside in the deepest underdensities of geometrically identified voids within the Sloan Digital Sky Survey. HI imaging of 55 galaxies with the Westerbork Synthesis Radio Telescope reveals morphological and kinematic signatures of ongoing interactions and gas accretion. We probe a total volume of 485Mpc^3^ within the voids, with an angular resolution of 8kpc at an average distance of 85Mpc. We reach column density sensitivities of 5x10^19^/cm^-2^, corresponding to an HI mass limit of 3x10^8^M_{sun}_. We detect HI in 41 galaxies, with total masses ranging from 1.7x10^8^ to 5.5x10^9^M_{sun}_. The upper limits on the 14 non-detections are not inconsistent with their luminosities, given their expected HI mass-to-light ratios. We find that the void galaxies are generally gas-rich, low-luminosity, blue disk galaxies, with optical and HI properties that are not unusual for their luminosity and morphology. The sample spans a range of absolute magnitudes (-16.1>M_r_>-20.4) and colors (0.06<g-r<0.87), and includes disk and irregular galaxies. We also identify three as early-type galaxies, all of which are not detected in HI. All galaxies have stellar masses less than 3x10^10^M_{sun}_, and many have kinematic and morphological signs of ongoing gas accretion, suggesting that the void galaxy population is still in the process of assembling. The small-scale clustering in the void, within 600kpc and 200km/s, is similar to that in higher density regions, and we identify 18 HI-rich neighboring galaxies in the voids. Most are within 100kpc and 100km/s of the targeted galaxy, and we find no significant population of HI-rich low-luminosity galaxies filling the voids, contrary to what is predicted by simulations.
- ID:
- ivo://CDS.VizieR/J/ApJ/853/62
- Title:
- Optical and NIR spectra and LCs of SN2016ija
- Short Name:
- J/ApJ/853/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our analysis of the Type II supernova DLT16am (SN2016ija). The object was discovered during the ongoing D<40Mpc (DLT40) one-day cadence supernova search at r~20.1mag in the "edge-on" nearby (D=20.0+/-4.0Mpc) galaxy NGC1532. The subsequent prompt and high-cadenced spectroscopic and photometric follow-up revealed a highly extinguished transient, with E(B-V)=1.95+/-0.15mag, consistent with a standard extinction law with R_V_=3.1 and a bright (M_V_=-18.48+/-0.77mag) absolute peak magnitude. A comparison of the photometric features with those of large samples of SNe II reveals a fast rise for the derived luminosity and a relatively short plateau phase, with a slope of S_50V_=0.84+/-0.04mag/50days, consistent with the photometric properties typical of those of fast-declining SNeII. Despite the large uncertainties on the distance and the extinction in the direction of DLT16am, the measured photospheric expansion velocity and the derived absolute V-band magnitude at ~50days after the explosion match the existing luminosity-velocity relation for SNeII.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/94
- Title:
- Optical and UV follow-up of 1ES 1927+654
- Short Name:
- J/ApJ/883/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the sudden optical and ultraviolet (UV) brightening of 1ES1927+654, which until now was known as a narrow-line active galactic nucleus (AGN). 1ES 1927+654 was part of the small and peculiar class of "true Type-2" AGNs that lack broad emission lines and line-of-sight obscuration. Our high-cadence spectroscopic monitoring captures the appearance of a blue, featureless continuum, followed several weeks later by the appearance of broad Balmer emission lines. This timescale is generally consistent with the expected light travel time between the central engine and the broadline emission region in (persistent) broadline AGN. Hubble Space Telescope spectroscopy reveals no evidence for broad UV emission lines (e.g., CIV{lambda}1549, CIII]{lambda}1909, MgII{lambda}2798), probably owing to dust in the broadline emission region. To the best of our knowledge, this is the first case where the lag between the change in continuum and in broadline emission of a "changing look" AGN has been temporally resolved. The nature and timescales of the photometric and spectral evolution disfavor both a change in line-of-sight obscuration and a change of the overall rate of gas inflow as driving the drastic spectral transformations seen in this AGN. Although the peak luminosity and timescales are consistent with those of tidal disruption events seen in inactive galaxies, the spectral properties are not. The X-ray emission displays a markedly different behavior, with frequent flares on timescales of hours to days, and will be presented in a companion publication.
- ID:
- ivo://CDS.VizieR/J/ApJ/876/115
- Title:
- Optical follow-up of ASAS-SN M dwarf flares
- Short Name:
- J/ApJ/876/115
- Date:
- 18 Jan 2022 15:06:46
- Publisher:
- CDS
- Description:
- The All-sky Automated Survey for Supernovae (ASAS-SN) is the only project in existence to scan the entire sky in optical light approximately every day, reaching a depth of g~18mag. Over the course of its first 4yr of transient alerts (2013-2016), ASAS-SN observed 53 events classified as likely M dwarf flares. We present follow-up photometry and spectroscopy of all 53 candidates, confirming flare events on 47 M dwarfs, one K dwarf, and one L dwarf. The remaining four objects include a previously identified T Tauri star, a young star with outbursts, and two objects too faint to confirm. A detailed examination of the 49 flare star light curves revealed an additional six flares on five stars, resulting in a total of 55 flares on 49 objects ranging in V-band contrast from {Delta}V=-1 to -10.2mag. Using an empirical flare model to estimate the unobserved portions of the flare light curve, we obtain lower limits on the V-band energy emitted during each flare, spanning log(E_V_/erg)=32-35, which are among the most energetic flares detected on M dwarfs. The ASAS-SN M dwarf flare stars show a higher fraction of H{alpha} emission, as well as stronger H{alpha} emission, compared to M dwarfs selected without reference to activity, consistent with belonging to a population of more magnetically active stars. We also examined the distribution of tangential velocities, finding that the ASAS-SN flaring M dwarfs are likely to be members of the thin disk and are neither particularly young nor old.
- ID:
- ivo://CDS.VizieR/J/AJ/159/61
- Title:
- Optical LCs & spectrum of the RCB star ZTF18abhjrcf
- Short Name:
- J/AJ/159/61
- Date:
- 07 Mar 2022 07:17:25
- Publisher:
- CDS
- Description:
- R Coronae Borealis stars (RCBs) constitute a rare class of stars that are hydrogen depleted and carbon enriched, possibly from white dwarf mergers. RCBs are identified by their stochastic dimming with photometric variations of as much as eight magnitudes. Hence, the discoveries of RCBs were heavily biased to the limited regions monitored by long-term microlensing experiments. However, recent studies of galactic RCBs have shown that they exhibit distinct mid-infrared colors originating from their cool circumstellar shells. The all-sky Wide-field Infrared Survey Explorer (WISE) survey thus facilitates the identification of RCB candidates. Therefore, combining the WISE colors with large-area time-domain surveys will enable us to discover more RCBs. Here we present the results of a first attempt to identify RCBs in the public Zwicky Transient Facility (ZTF) alert stream, using the alert broker ANTARES. We identify a candidate RCB using the infrared color selection by Tisserand+, 2013A&A...551A..77T and large light curve variations in the optical from ZTF. We then conduct subsequent observations using the FLOYDS spectrograph at the Las Cumbres Observatory and confirm ZTF18abhjrcf as a bona fide RCB. This demonstrates the potential to discover uncharted RCBs as ZTF and other time-domain surveys continue to operate.
- ID:
- ivo://CDS.VizieR/J/AJ/160/235
- Title:
- Optical photometry and RVs of TOI-481b and TOI-892b
- Short Name:
- J/AJ/160/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of two new 10 day period giant planets from the Transiting Exoplanet Survey Satellite mission, whose masses were precisely determined using a wide diversity of ground-based facilities. TOI-481b and TOI-892b have similar radii (0.99{+/-}0.01R_Jup_ and 1.07{+/-}0.02R_Jup_, respectively), and orbital periods (10.3311days and 10.6266days, respectively), but significantly different masses (1.53{+/-}0.03M_Jup versus 0.95{+/-}0.07M_Jup_, respectively). Both planets orbit metal-rich stars ([Fe/H]=+0.26{+/-}0.05dex and [Fe/H]=+0.24{+/-}0.05 for TOI-481 and TOI-892, respectively) but at different evolutionary stages. TOI-481 is a M_*_=1.14{+/-}0.02M_{odot}_, R_*_=1.66{+/-}0.02R_{odot}_ G-type star (Teff=5735{+/-}72K), that with an age of 6.7Gyr, is in the turn-off point of the main sequence. TOI-892 on the other hand, is a F-type dwarf star (Teff=6261{+/-}80K), which has a mass of M_*_=1.28{+/-}0.03M_{odot}_ and a radius of R_*_=1.39{+/-}0.02R_{odot}_. TOI-481b and TOI-892b join the scarcely populated region of transiting gas giants with orbital periods longer than 10days, which is important to constrain theories of the formation and structure of hot Jupiters.
- ID:
- ivo://CDS.VizieR/J/ApJ/758/25
- Title:
- Optical properties of WISE galaxies
- Short Name:
- J/ApJ/758/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a dense, complete redshift survey, the Smithsonian Hectospec Lensing Survey (SHELS), covering a 4deg^2^ region of a deep imaging survey, the Deep Lens Survey (DLS), to study the optical spectral properties of Wide-field Infrared Survey Explorer (WISE) 22{mu}m selected galaxies. Among 507 WISE 22{mu}m selected sources with (S/N)_22{mu}m_>=3 ({approx}S_22{mu}m_>~2.5mJy), we identify the optical counterparts of 481 sources (~98%) at R<25.2 in the very deep, DLS R-band source catalog. Among them, 337 galaxies at R<21 have SHELS spectroscopic data. Most of these objects are at z<0.8. The infrared (IR) luminosities are in the range 4.5x10^8^(L_{sun}_)<~L_IR_<~5.4x10^12^(L_{sun}_). Most 22{mu}m selected galaxies are dusty star-forming galaxies with a small (<1.5) 4000{AA} break. The stacked spectra of the 22 {mu}m selected galaxies binned in IR luminosity show that the strength of the [O III] line relative to H{beta} grows with increasing IR luminosity. The optical spectra of the 22{mu}m selected galaxies also show that there are some (~2.8%) unusual galaxies with very strong [Ne III] {lambda}3869, 3968 emission lines that require hard ionizing radiation such as active galactic nuclei (AGNs) or extremely young massive stars. The specific star formation rates (sSFRs) derived from the 3.6 and 22{mu}m flux densities are enhanced if the 22{mu}m selected galaxies have close late-type neighbors. The sSFR distribution of the 22{mu}m selected galaxies containing AGNs is similar to the distribution for star-forming galaxies without AGNs. We identify 48 dust-obscured galaxy candidates with large (>~1000) mid-IR to optical flux density ratio. The combination of deep photometric and spectroscopic data with WISE data suggests that WISE can probe the universe to z~2.
- ID:
- ivo://CDS.VizieR/J/ApJ/875/85
- Title:
- Optical search for SNRs in NGC6946 with WIYN & GMOS
- Short Name:
- J/ApJ/875/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relatively nearby spiral galaxy NGC 6946 is one of the most actively star-forming galaxies in the local universe. Ten supernovae (SNe) have been observed since 1917, and hence NGC 6946 surely contains a large number of supernova remnants (SNRs). Here we report a new optical search for these SNRs using narrowband images obtained with the WIYN telescope. We identify 147 emission nebulae as likely SNRs, based on elevated [SII]:H{alpha} ratios compared to HII regions. We have obtained spectra of 102 of these nebulae with Gemini North-GMOS; of these, 89 have [SII]:H{alpha} ratios greater than 0.4, the canonical optical criterion for identifying SNRs. There is very little overlap between our sample and the SNR candidates identified by Lacey+ (1997ApJS..109..417L) from radio data. Also, very few of our SNR candidates are known X-ray sources, unlike the situation in some other galaxies such as M33 and M83. The emission-line ratios, e.g., [NII]:H{alpha}, of the candidates in NGC 6946 are typical of those observed in SNR samples from other galaxies with comparable metallicity. None of the candidates observed in our low-resolution spectra show evidence of anomalous abundances or significant velocity broadening. A search for emission at the sites of all the historical SNe in NGC 6946 resulted in detections for only two: SN 1980K and SN 2004et. Spectra of both show very broad, asymmetric line profiles, consistent with the interaction between SN ejecta and the progenitor star's circumstellar material, as seen in late spectra from other core-collapse SNe of similar age.