Search

Start Over Subject optical astronomy
1781. Keck/MOSFIRE spectroscopy of ZFOURGE galaxies
ID:
ivo://CDS.VizieR/J/ApJ/834/101
Title:
Keck/MOSFIRE spectroscopy of ZFOURGE galaxies
Short Name:
J/ApJ/834/101
Date:
21 Oct 2021
Publisher:
CDS
Description:
We compare galaxy scaling relations as a function of environment at z~2 with our ZFIRE survey where we have measured H{alpha} fluxes for 90 star-forming galaxies selected from a mass-limited (log(M_*_/M_{sun}_)>9) sample based on ZFOURGE. The cluster galaxies (37) are part of a confirmed system at z=2.095 and the field galaxies (53) are at 1.9<z<2.4; all are in the COSMOS legacy field. There is no statistical difference between H{alpha}-emitting cluster and field populations when comparing their star formation rate (SFR), stellar mass (M_*_), galaxy size (r_eff_), SFR surface density ({Sigma}(H{alpha}_star_)), and stellar age distributions. The only difference is that at fixed stellar mass, the H{alpha}-emitting cluster galaxies are log(r_eff_)~0.1 larger than in the field. Approximately 19% of the H{alpha} emitters in the cluster and 26% in the field are IR-luminous (L_IR_>2x10^11^L_{sun}_). Because the luminous IR galaxies in our combined sample are ~5 times more massive than the low-IR galaxies, their radii are ~70% larger. To track stellar growth, we separate galaxies into those that lie above, on, or below the H{alpha} star-forming main sequence (SFMS) using {Delta}SFR(M*)=+/-0.2dex. Galaxies above the SFMS (starbursts) tend to have higher H{alpha} SFR surface densities and younger light-weighted stellar ages than galaxies below the SFMS. Our results indicate that starbursts (+SFMS) in the cluster and field at z~2 are growing their stellar cores. Lastly, we compare to the (SFR-M*) relation from Rhapsody-G cluster simulations and find that the predicted slope is nominally consistent with the observations. However, the predicted cluster SFRs tend to be too low by a factor of ~2, which seems to be a common problem for simulations across environment.
1782. K2 Ecliptic Plane Input Catalog (EPIC)
ID:
ivo://CDS.VizieR/IV/34
Title:
K2 Ecliptic Plane Input Catalog (EPIC)
Short Name:
IV/34
Date:
21 Oct 2021
Publisher:
CDS
Description:
The K2 Mission (Howell+, 2014PASP..126..398H) uses the Kepler spacecraft to obtain high-precision photometry over ~80 day campaigns in the ecliptic plane. The Ecliptic Plane Input Catalog (EPIC) provides coordinates, photometry, and kinematics based on a federation of all-sky catalogs to support target selection and target management for the K2 mission.
1783. KELT light curve of the M82 SN 2014J
ID:
ivo://CDS.VizieR/J/ApJ/799/105
Title:
KELT light curve of the M82 SN 2014J
Short Name:
J/ApJ/799/105
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report observations of the bright M82 supernova 2014J serendipitously obtained with the Kilodegree Extremely Little Telescope (KELT). The supernova (SN) was observed at high cadence for over 100 days, from pre-explosion, to early rise and peak times, through the secondary bump. The high cadence KELT data with high signal-to-noise ratio is completely unique for SN 2014J and for any other SNIa, with the exception of the (yet) unpublished Kepler data. Here, we report determinations of the SN explosion time and peak time. We also report measures of the "smoothness" of the light curve on timescales of minutes/hours never before probed, and we use this to place limits on energy produced from short-lived isotopes or inhomogeneities in the explosion or the circumstellar medium. From the non-observation of significant perturbations of the light curves, we derive a 3{sigma} upper limit corresponding to 8.7x10^36^erg/s for any such extra sources of luminosity at optical wavelengths.
1784. KELT-1 photometry and spectroscopy follow-up
ID:
ivo://CDS.VizieR/J/ApJ/761/123
Title:
KELT-1 photometry and spectroscopy follow-up
Short Name:
J/ApJ/761/123
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the discovery of KELT-1b, the first transiting low-mass companion from the wide-field Kilodegree Extremely Little Telescope-North (KELT-North) transit survey. A joint analysis of the spectroscopic, radial velocity, and photometric data indicates that the V=10.7 primary is a mildly evolved mid-F star with T_eff_=6516+/-49K, logg=4.228^+0.014^_-0.021_, and [Fe/H]=0.052+/-0.079, with an inferred mass M_*_=1.335+/-0.063M_{sun}_ and radius R_*_=1.471^+0.045^_-0.035_R_{sun}_. The companion is a low-mass brown dwarf or a super-massive planet with mass M_P_=27.38+/-0.93M_Jup_ and radius R_P_=1.116^+0.038^_-0.029_R_Jup_. The companion is on a very short (~29 hr) period circular orbit, with an ephemeris T_c_ (BJD_TDB_)=2455909.29280+/-0.00023 and P=1.217501+/-0.000018 days. KELT-1b receives a large amount of stellar insolation, resulting in an estimated equilibrium temperature assuming zero albedo and perfect redistribution of T_eq_=2423^+34^_-27_K. Comparison with standard evolutionary models suggests that the radius of KELT-1b is likely to be significantly inflated. Adaptive optics imaging reveals a candidate stellar companion to KELT-1 with a separation of 588+/-1mas, which is consistent with an M dwarf if it is at the same distance as the primary. Rossiter-McLaughlin measurements during transit imply a projected spin-orbit alignment angle {lambda}=2+/-16deg, consistent with a zero obliquity for KELT-1. Finally, the vsinI_*_=56+/-2km/s of the primary is consistent at ~2{sigma} with tidal synchronization. Given the extreme parameters of the KELT-1 system, we expect it to provide an important testbed for theories of the emplacement and evolution of short-period companions, as well as theories of tidal dissipation and irradiated brown dwarf atmospheres.
1785. Kepler-13AB aperture photometry
ID:
ivo://CDS.VizieR/J/AJ/158/113
Title:
Kepler-13AB aperture photometry
Short Name:
J/AJ/158/113
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the high-resolution imaging instrument, 'Alopeke, at the Gemini-N telescope, we obtained simultaneous two-channel time-series observations of the binary exoplanet host star Kepler13-AB. Our optical observations were obtained during a transit event of the exoplanet Kepler-13b and light curves were produced using both speckle interferometric and aperture photometry techniques. Both techniques confirm that the transiting object orbits the star Kepler-13A while different transit depths are seen across the optical wavelength range, being ~2 times deeper in the blue. These measurements, as well as mass determinations in the literature, are consistent with Kepler-13b being a highly irradiated gas giant with a bloated atmosphere. Our observations highlight the ability of high-resolution speckle imaging to not only assess binarity in exoplanet host stars but robustly determine which of the stars the transiting object actually orbits.
1786. Kepler-278 and Kepler-391 spectra
ID:
ivo://CDS.VizieR/J/A+A/634/A29
Title:
Kepler-278 and Kepler-391 spectra
Short Name:
J/A+A/634/A29
Date:
21 Oct 2021
Publisher:
CDS
Description:
Kepler-278 and Kepler-391 are two of the three evolved stars on the red giant branch (RGB) known to date, to host multiple short-period transiting planets. Moreover, these planets are among the smallest discovered around RGB stars. Here, we present a detailed stellar and planetary characterization of these remarkable systems. Methods. Based on high-quality spectra from Gemini-GRACES of Kepler-278 and Kepler-391, we obtained refined stellar parameters and precise chemical abundances of 25 elements. Nine of these elements and the carbon isotopic ratios, ^12^C/^13^C, were not previously measured. Also, combining our new stellar parameters with a photodynamical analysis of the Kepler light curves, we determined accurate planetary properties of both systems. Results. Our revised stellar parameters agree reasonably well with most of the previous results, although we find that Kepler-278 is ~15% less massive than previously reported. The abundances of C, N, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, and Ce, in both stars, are consistent with those of evolved nearby thin disk stars. Kepler-391 presents a relatively high abundance of lithium (A(Li)NLTE=1.29+/-0.09dex), which is likely a remnant from the main-sequence phase. The precise spectroscopic parameters of Kepler-278 and Kepler-391 along with their high 12 C/13 C ratios show that both stars are just starting their ascent on the RGB. The planets Kepler-278b, Kepler-278c, and Kepler-391c are warm sub-Neptunes, whilst Kepler-391b is a hot sub-Neptune that falls in the Hot Super-Earth desert and therefore it might be undergoing photo-evaporation of its outer envelope. The high-precision obtained in the transit times allowed us not only to confirm Kepler-278c's TTV signal but also to find evidence of a previously undetected TTV signal for the inner planet Kepler-278b. From the presence of gravitational interaction between these bodies we constrain, for the first time, the mass of Kepler-278b (Mp=56M_Earth_) and Kepler-278c (Mp=35M_Earth_). The mass limits, coupled with our precise determinations of the planetary radii, suggest that their bulk compositions are consistent with a significant amount of water content and the presence of H2 gaseous envelopes. Finally, our photodynamical analysis also shows that the orbits of both planets around Kepler-278 are highly eccentric (e~0.7) and, surprisingly, coplanar. Further observations (e.g., precise radial velocities) of this system are needed to confirm the eccentricity values presented here.
1787. Kepler cycle 1 observations of low-mass stars
ID:
ivo://CDS.VizieR/J/AJ/143/4
Title:
Kepler cycle 1 observations of low-mass stars
Short Name:
J/AJ/143/4
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have analyzed Kepler light curves for 849 stars with Teff<=5200K from our Cycle 1 Guest Observer program. We identify six new eclipsing binaries, one of which has an orbital period of 29.91 days and two of which are probably W UMa variables. In addition, we identify a candidate "warm Jupiter" exoplanet. We further examine a subset of 670 sources for variability. Of these objects, 265 stars clearly show periodic variability that we assign to rotation of the low-mass star. At the photometric precision level provided by Kepler, 251 of our objects showed no evidence for variability. We were unable to determine periods for 154 variable objects. We find that 79% of stars with Teff<=5200K are variable. The rotation periods we derive for the periodic variables span the range 0.31days<=Prot<=126.5days. A considerable number of stars with rotation periods similar to the solar value show activity levels that are 100 times higher than the Sun.
1788. Kepler Follow-up Observation Program. II. Spectro.
ID:
ivo://CDS.VizieR/J/ApJ/861/149
Title:
Kepler Follow-up Observation Program. II. Spectro.
Short Name:
J/ApJ/861/149
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from spectroscopic follow-up observations of stars identified in the Kepler field and carried out by teams of the Kepler Follow-up Observation Program. Two samples of stars were observed over 6yr (2009-2015): 614 standard stars (divided into "platinum" and "gold" categories) selected based on their asteroseismic detections and 2667 host stars of Kepler Objects of Interest (KOIs), most of them planet candidates. Four data analysis pipelines were used to derive stellar parameters for the observed stars. We compare the Teff, log(g), and [Fe/H] values derived for the same stars by different pipelines; from the average of the standard deviations of the differences in these parameter values, we derive error floors of ~100K, 0.2dex, and 0.1dex for Teff, log(g), and [Fe/H], respectively. Noticeable disagreements are seen mostly at the largest and smallest parameter values (e.g., in the giant star regime). Most of the log(g) values derived from spectra for the platinum stars agree on average within 0.025dex (but with a spread of 0.1-0.2dex) with the asteroseismic log(g) values. Compared to the Kepler Input Catalog (KIC), the spectroscopically derived stellar parameters agree within the uncertainties of the KIC but are more precise and thus an important contribution toward deriving more reliable planetary radii.
1789. Kepler light curves of Jovian Trojan asteroids
ID:
ivo://CDS.VizieR/J/ApJS/254/7
Title:
Kepler light curves of Jovian Trojan asteroids
Short Name:
J/ApJS/254/7
Date:
21 Oct 2021
Publisher:
CDS
Description:
Various properties of Jovian Trojan asteroids such as composition, rotation periods, and photometric amplitudes, or the rate of binarity in the population, can provide information and constraints on the evolution of the group and of the solar system itself. Here we present new photometric properties of 45 Jovian Trojans from the K2 mission of the Kepler space telescope, and present phase-folded light curves for 44 targets, including (11351) Leucus, one of the targets of the Lucy mission. We extend our sample to 101 asteroids with previous K2 Trojan measurements, then compare their combined amplitude and frequency distributions to other ground-based and space data. We show that there is a dichotomy in the periods of Trojans with a separation at ~100hr. We find that 25% of the sample are slow rotators (P>=30hr), an excess that can be attributed to binary objects. We also show that 32 systems can be classified as potential detached binary systems. Finally, we calculate density and rotation constraints for the asteroids. Both the spin barrier and fits to strengthless ellipsoid models indicate low densities and thus compositions similar to populations of comets and trans-Neptunian objects throughout the sample. This supports the scenario of outer solar system origin for Jovian Trojans.
1790. K giants at the South Galactic Pole
ID:
ivo://CDS.VizieR/J/A+AS/97/835
Title:
K giants at the South Galactic Pole
Short Name:
J/A+AS/97/835
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)