Radius Of Re Research Articles

The Transiting Multi-planet System HD 3167: A 5.7 M⊕ Super-Earth and an 8.3 M⊕ Mini-Neptune

Abstract HD 3167 is a bright (V = 8.9 mag) K0 V star observed by NASA’s K2 space mission during its Campaign 8. It has recently been found to host two small transiting planets, namely, HD 3167b, an ultra-short-period (0.96 days) super-Earth, and HD 3167c, a mini-Neptune on a relatively long-period orbit (29.85 days). Here we present an intensive radial velocity (RV) follow-up of HD 3167 performed with the FIES@NOT, HARPS@ESO-3.6 m, and HARPS-N@TNG spectrographs. We revise the system parameters and determine radii, masses, and densities of the two transiting planets by combining the K2 photometry with our spectroscopic data. With a mass of 5.69 ± 0.44 M ⊕, a radius of 1.574 ± 0.054 R ⊕, and a mean density of , HD 3167b joins the small group of ultra-short-period planets known to have rocky terrestrial compositions. HD 3167c has a mass of M ⊕ and a radius of R ⊕, yielding a mean density of , indicative of a planet with a composition comprising a solid core surrounded by a thick atmospheric envelope. The rather large pressure scale height (∼350 km) and the brightness of the host star make HD 3167c an ideal target for atmospheric characterization via transmission spectroscopy across a broad range of wavelengths. We found evidence of additional signals in the RV measurements but the currently available data set does not allow us to draw any firm conclusions on the origin of the observed variation.

The Progenitor and Early Evolution of the Type IIb SN 2016gkg

Abstract We report initial observations and analysis on the Type IIb SN 2016gkg in the nearby galaxy NGC 613. SN 2016gkg exhibited a clear double-peaked light curve during its early evolution, as evidenced by our intensive photometric follow-up campaign. SN 2016gkg shows strong similarities with other Type IIb SNe, in particular, with respect to the He i emission features observed in both the optical and near-infrared. SN 2016gkg evolved faster than the prototypical Type IIb SN 1993J, with a decline similar to that of SN 2011dh after the first peak. The analysis of archival Hubble Space Telescope images indicate a pre-explosion source at SN 2016gkg’s position, suggesting a progenitor star with a ∼mid-F spectral type and initial mass M , depending on the distance modulus adopted for NGC 613. Modeling the temperature evolution within of explosion, we obtain a progenitor radius of R , smaller than that obtained from the analysis of the pre-explosion images ( R ).

KILOPARSEC-SCALE DUST DISKS IN HIGH-REDSHIFT LUMINOUS SUBMILLIMETER GALAXIES

ABSTRACT We present high-resolution (0.″16) 870 μm Atacama Large Millimeter/submillimeter Array (ALMA) imaging of 16 luminous ( ) submillimeter galaxies (SMGs) from the ALESS survey of the Extended Chandra Deep Field South. This dust imaging traces the dust-obscured star formation in these galaxies on ∼1.3 kpc scales. The emission has a median effective radius of R e = 0.″24 ± 0.″02, corresponding to a typical physical size of 1.8 ± 0.2 kpc. We derive a median Sérsic index of n = 0.9 ± 0.2, implying that the dust emission is remarkably disk-like at the current resolution and sensitivity. We use different weighting schemes with the visibilities to search for clumps on 0.″12 (∼1.0 kpc) scales, but we find no significant evidence for clumping in the majority of cases. Indeed, we demonstrate using simulations that the observed morphologies are generally consistent with smooth exponential disks, suggesting that caution should be exercised when identifying candidate clumps in even moderate signal-to-noise ratio interferometric data. We compare our maps to comparable-resolution Hubble Space Telescope -band images, finding that the stellar morphologies appear significantly more extended and disturbed, and suggesting that major mergers may be responsible for driving the formation of the compact dust disks we observe. The stark contrast between the obscured and unobscured morphologies may also have implications for SED fitting routines that assume the dust is co-located with the optical/near-IR continuum emission. Finally, we discuss the potential of the current bursts of star formation to transform the observed galaxy sizes and light profiles, showing that the descendants of these SMGs are expected to have stellar masses, effective radii, and gas surface densities consistent with the most compact massive ( 1–2 × 1011 ) early-type galaxies observed locally.

Structural, electronic and magnetic properties of RE3+-doping in CoFe2O4: A first-principles study

RE3+(RE=La, Ce, Pr, Nd, Eu, Gd) doped cobalt ferrite (CoFe2O4) have been studied systematically by the first-principles calculations based on density functional theory within the generalized gradient approximation with Hubbard corrections (GGA+U) . The significant effects of RE3+doping on the crystal structure, electronic and magnetic properties of CoFe2O4 have been explored. The calculated results show that the RE ions prefer substituting Fe3+ located at the octahedral sites. And the lattice constant of CoFe1.875RE0.125O4 (RE=La, Ce, Pr, Nd, Eu and Gd) decreases due to the decreasing ionic radius of RE as the atomic number increases. The magnetic properties depend on the unpaired 4f electrons of RE3+ ions. The net magnetic moment of CoFe2O4 increases by doping with Eu and Gd, the reason is that there are more unpaired 4f electrons for Eu3+and Gd3+. However, the net magnetic moment of CoFe2O4 decreases by doping with La, Ce, Pr, and Nd, due to the reason that these RE ions prefer their low spin configurations.

MCG+08-22-082: A DOUBLE CORE AND BOXY APPEARANCE DWARF LENTICULAR GALAXY SUSPECTED TO BE A MERGER REMNANT

ABSTRACT We present a study on the dwarf lenticular galaxy MCG+08-22-082 (U141), located in the Ursa Major cluster, blue-centered, double-cored, and having a boxy appearance. Using publicly available data from the Sloan Digital Sky Survey (SDSS), we perform an analysis of the structural and stellar population properties of the galaxy and the cores. We find that the light profile of U141 follows an exponential law. U141 has a brightness of M r = − 16.01 mag, and an effective radius of R e = 1.7 kpc . The boxiness parameter a 4 / a is mostly between 0 and −0.05 in the inner parts, reaching an extreme of about −0.1. Double cores are seen at the center of U141; each of these cores has a stellar mass of ∼106 M ☉ and the separation between them is ∼300 pc. Optical spectroscopy of these cores shows prominent emission in Hα, suggesting ongoing star-forming activities. We interpret these morphological properties and speculate that U141 is a merger remnant of two disk galaxies. Thus, we might have discovered an intermediate stage of merging, providing possible evidence of double cores in the center of the galaxy.

Thermal properties and thermoelasticity of L12 ordered Al3RE (RE = Er, Tm, Yb, Lu) phases: A first-principles study

Thermal properties and thermoelasticity of L12 Al3RE (RE=Er, Tm, Yb, Lu) phases have been studied by first principles calculations combined with density functional perturbation theory and quasi-harmonic approximation. In the temperature range considered, the calculated thermal properties including equilibrium volume, isothermal bulk modulus, Grüneisen parameters for different Al3RE phases exhibit analogous variation tendency and the numerical values are associated with the atomic radius of RE. The calculated thermal expansion and heat capacity for different Al3RE are almost indistinguishable from each other. The obtained elastic constants and polycrystalline elastic moduli exhibit gentle softening trends with temperature, and the variation tendency is also very similar. In the temperature range considered, Al3RE phases are nearly isotropic. The present study would be valuable for future investigation and design of high temperature Al alloys.

KIM 3: AN ULTRA-FAINT STAR CLUSTER IN THE CONSTELLATION OF CENTAURUS

ABSTRACT We report the discovery of an ultra-faint star cluster in the constellation of Centaurus. This new stellar system, Kim 3, features a half-light radius of r h = 2.29 − 0.52 + 1.28 ?> pc and a total luminosity of M V = +0.7 ± 0.3. Approximately 26 stars are identified as candidate member stars down to four magnitudes below the main-sequence turn-off, which makes Kim 3 the least luminous star cluster known to date. The compact physical size and extreme low luminosity place it close to faint star clusters in the size–luminosity plane. The stellar population of Kim 3 appears to be relatively young ( 9.5 − 1.7 + 3.0 ?> Gyr) and metal-poor ([Fe/H] = − 1.6 − 0.30 + 0.45 ?> ) at a heliocentric distance of 15.14 − 0.28 + 1.00 ?> kpc. The cluster lacks a well-defined center, and a small but prominent group of stars consistent with the Kim 3 isochrone is present approximately 9.7 pc in projection south of the cluster center. Both are signs of the cluster being in the final stage of tidal disruption.

SDSS J085431.18+173730.5: THE FIRST COMPACT ELLIPTICAL GALAXY HOSTING AN ACTIVE NUCLEUS

ABSTRACT We report the discovery of a rare compact early-type galaxy, SDSS J085431.18+173730.5 (hereafter cE_AGN). It has a half-light radius of R e = 490 pc and a brightness of M r = −18.08 mag. Optical spectroscopy available from the Sloan Digital Sky Survey (SDSS) reveals the presence of prominent broad-line emissions with the Hα broad component width of FWHM = 2400 km s−1. The black hole (BH) mass, as estimated from the luminosity and width of the broad Hα emission, is 2.1 × 106 M ☉ ?> . With the help of surface photometry, we perform a detailed analysis of the structural properties. The observed light distribution is best modeled with a double Sérsic function. Fixing the outer component as an exponential disk, we find that the inner component has a Sérsic index of n = 1.4. Considering the inner component as bulge/spheroidal we find that cE_AGN remains consistent in both the BH mass–bulge mass relation and the BH mass–bulge Sérsic index relation. Given these observational properties, we discuss its possible origin investigating the surrounding environment where it is located.

STRUCTURE OF THE ACCRETION DISK IN THE LENSED QUASAR Q2237+0305 FROM MULTI-EPOCH AND MULTI-WAVELENGTH NARROWBAND PHOTOMETRY

ABSTRACT We present estimates for the size and the logarithmic slope of the disk temperature profile of the lensed quasar Q2237+0305, independent of the component velocities. These estimates are based on six epochs of multi-wavelength narrowband images from the Nordic Optical Telescope. For each pair of lensed images and each photometric band, we determine the microlensing amplitude and chromaticity using pre-existing mid-IR photometry to define the baseline for no microlensing magnification. A statistical comparison of the combined microlensing data (6 epochs × 5 narrow bands × 6 image pairs) with simulations based on microlensing magnification maps gives Bayesian estimates for the half-light radius of R 1 / 2 = 8.5 − 4.0 + 7.5 ⟨ M ⟩ / 0.3 M ⊙ ?> lt-day, and p = 0.95 ± 0.33 for the exponent of the logarithmic temperature profile T ∝ R − 1 / p ?> . This size estimate is in good agreement with most recent studies. Other works based on the study of single microlensing events predict smaller sizes, but could be statistically biased by focusing on high-magnification events.

Structural characteristics, magnetic properties of Re2NiMnO6 (Re = La, Pr, Nd, Sm, Y) thin films on (001) LaAlO3 by simple polymer assisted deposition

Re2NiMnO6 (Re=La, Pr, Nd, Sm, Y) epitaxial thin films grown on (001) LaAlO3 substrates were obtained via a simple polymer assisted deposition method. The XRD θ/2θ scans, ω scans, and φ scans indicate that the films are single-phase epitaxial films. It is found that there is a ferromagnetic (FM) transition with the temperature decreasing from room temperature for all the films. The Raman mode positions shift toward the low frequency with the substitution of La by a smaller rare earth element. The FM transition temperature Tc decreases as the A-site ionic radius decreasing. Moreover, all the FM transition temperatures (Tc) of the Re2NiMnO6 films are lower than those corresponding values of the bulks, indicating the ferromagnetic interaction weakening. It is suggested that the ferromagnetic interaction is affected by the strain existing in the film through affecting the B(B′)O6 octahedra and the cation disorder related to the ionic radius of Re, which can be used as an effective way to improve the magnetic properties of the film and obtain the higher Tc functional materials.

SUBLIMATION-DRIVEN ACTIVITY IN MAIN-BELT COMET 313P/GIBBS

We present an observational and dynamical study of newly discovered main-belt comet 313P/Gibbs. We find that the object is clearly active both in observations obtained in 2014 and in precovery observations obtained in 2003 by the Sloan Digital Sky Survey, strongly suggesting that its activity is sublimation-driven. This conclusion is supported by a photometric analysis showing an increase in the total brightness of the comet over the 2014 observing period, and dust modeling results showing that the dust emission persists over at least three months during both active periods, where we find start dates for emission no later than 2003 July 24+/-10 for the 2003 active period and 2014 July 28+/-10 for the 2014 active period. From serendipitous observations by the Subaru Telescope in 2004 when the object was apparently inactive, we estimate that the nucleus has an absolute R-band magnitude of H_R=17.1+/-0.3, corresponding to an effective nucleus radius of r_e~1.00+/-0.15 km. The object's faintness at that time means we cannot rule out the presence of activity, and so this computed radius should be considered an upper limit. We find that 313P's orbit is intrinsically chaotic, having a Lyapunov time of T_l=12000 yr and being located near two 3-body mean-motion resonances with Jupiter and Saturn, 11J-1S-5A and 10J+12S-7A, yet appears stable over >50 Myr in an apparent example of stable chaos. We furthermore find that 313P is the second main-belt comet, after P/2012 T1 (PANSTARRS), to belong to the ~155 Myr old Lixiaohua asteroid family.

Theoretical study on the influence of rare earth doping on the electronic structure and magnetic properties of cobalt ferrite

Spinel ferrite is one of the very important magnetic materials, having the unique physical properties, chemical properties, magnetic properties, and electronic properties. CoFe2O4 is widely used due to their good electromagnetic properties. We have studied the electronic structure and magnetic properties of CoRE0.125Fe1.875O4 (RE = Nd, Eu, Gd)by first-principles plane-wave pseudopotential method based on density functional theory (DFT), combined with the generalized gradient approximation (GGA + U) in this paper. Results show that the lattice constants of the compunds CoFe1.875RE0.125O4 (RE=Nd, Eu and Gd) will decrease due to the decreasing ionic radius of RE as the atomic number increases. Their magnetic properties depend on the unpaired 4f electrons of RE3+ ions, and the net magnetic moment of CoFe2O4 will increase with Eu and Gd doping, mainly because there are more unpaired 4f electrons in Eu3+ and Gd3+. Thus the doping of Eu3+ and Gd3+ may have a greater impact on the magnetic properties of cobalt ferrite. The contribution from the doping of Nd is not remarkable on the magnetic properties, since the Nd3 + ion, having a larger ionic radius, could distort the crystal structure of CoFe2O4.

THE CONTINUED OPTICAL TO MID-INFRARED EVOLUTION OF V838 MONOCEROTIS*

ABSTRACT The eruptive variable V838 Monocerotis (V838 Mon) gained notoriety in 2002 when it brightened nine magnitudes in a series of three outbursts and then rapidly evolved into an extremely cool supergiant. We present optical, near-infrared (near-IR), and mid-IR spectroscopic and photometric observations of V838 Mon obtained between 2008 and 2012 at the Apache Point Observatory 3.5 m, NASA IRTF 3 m, and Gemini South 8 m telescopes. We contemporaneously analyze the optical and IR spectroscopic properties of V838 Mon to arrive at a revised spectral type L3 supergiant and effective temperature T eff ∼ 2000 ?> –2200 K. Because there are no existing optical observational data for L supergiants, we speculate that V838 Mon may represent the prototype for L supergiants in this wavelength regime. We find a low level of Hα emission present in the system, consistent with interaction between V838 Mon and its B3V binary; however, we cannot rule out a stellar collision as the genesis event, which could result in the observed Hα activity. Based upon a two-component blackbody fit to all wavelengths of our data, we conclude that, as of 2009, a shell of ejecta surrounded V838 Mon at a radius of R = 263 ± 10 ?> AU with a temperature of T = 285 ± 2 ?> K. This result is consistent with IR interferometric observations from the same era and predictions from the Lynch et al. model of the expanding system, which provides a simple framework for understanding this complicated system.

Novel Garnet-structure Ca(2)GdZr(2)(AlO(4))3:Ce(3+) phosphor and its structural tuning of optical properties.

Aluminate garnet phosphors Ca2GdZr2(AlO4)3:Ce(3+) (CGZA:Ce(3+)) for solid-state white lighting sources are reported. The crystal structure and Mulliken bonding population of the CGZA:Ce(3+) have been analyzed. The larger 5d ((2)D) barycenter shift εc and smaller phenomenological parameter 10Dq of Ce(3+) in CGZA are related to the larger covalent character of Ce-O. The tuning spectral properties of the Ce(3+)-doped CGZA-based isostructural phosphors are presented. The splitting of cubic crystal field energy level (2)Eg in Ca2REZr2(AlO4)3:Ce(3+) (CREZA:Ce(3+)) (RE = Lu, Y, and Gd) increases as the radius of RE(3+) increases, and the splitting of (2)Eg may dominate the difference of spectroscopic red-shift D(A) in CREZA:Ce(3+). The splitting of the (2)Eg in CaGd2ZrSc(AlO4)3:Ce(3+) (CGZSA:Ce(3+)) phosphors increases seemly due to the decreasing of the covalent character of Ce-O. Thermal quenching properties of Ce(3+)-doped CGZA-based isostructural phosphors are also presented and analyzed. For CREZA:Ce(3+) phosphors, the increasing of the radius of RE(3+) results in an enhancement of thermal quenching. The quenching of CGZSA:Ce(3+) is obviously stronger mainly due to the smaller energy difference between the lowest 5d excited state and 4f ground state.

Modeling by autonomous Hamiltonian system: fixing the sign of a parameter

We illustrate how the application of autonomous Hamiltonian dynamical system can definitively fix a sign for an otherwise indefinite sign of a certain astrophysical parameter. To illustrate it, we shall consider the Mannheim–Kazanas-de Sitter solution of Weyl conformal gravity containing the parameter γ, which is believed to be significant in the galactic halo gravity. However, the sign of γ has so far been ambiguous. The strategy we adopt to fix it is to look for a finite maximum radius up to which the halo supports stable material circular orbits inside the de Sitter radius. The maximum radius for several observed lenses are calculated for both signs of γ, and with the observed value of cosmological constant Λ. These lenses (all having approximately the Einstein radius R E ≈ 1023 cm) consistently yield a maximum radius ( $$ R_{ \max }^{\text{stable}} \cong 4.25 \times 10^{27} {\text{cm}} $$ ) inside the de Sitter radius of the universe only when γ is negative, while a positive γ yields $$ R_{ \max }^{\text{stable}} $$ always exceeding the de Sitter radius.

Composition and temperature-induced structural evolution in La, Sm, and Dy substituted BiFeO3 epitaxial thin films at morphotropic phase boundaries

Detailed structural investigations on the substitution-induced structural phase transition from the rhombohedral phase to an orthorhombic phase in (Bi,RE)FeO3 epitaxial thin films (RE = La, Sm, and Dy) grown on (100) SrTiO3 substrates are presented. X ray diffraction reveals that the unit cell dimensions of the orthorhombic phase are strongly dependent on the type of the RE dopant. For RE = La3+ ion, which has an ionic size comparable to the Bi3+ ion, the unit cell is found to be a0 × a0 × 2a0, where a0 is the pseudo-cubic lattice parameter. This is in contrast with the √2a0 × √2a0 × 2a0 unit cell for the case of smaller ionic radius RE (= Sm and Dy) elements. While clear double-hysteresis loops in the polarization versus electric-field curves due to field-induced transitions are observed for smaller ionic radius RE (= Sm and Dy), no signature of the double hysteresis loops is observed for the RE = La case across the structural boundary. We have also performed systematic tracking of the structural phases as functions of the RE composition and temperature, based on which we propose a phase diagram. This work reveals that the ionic size of the RE element plays a critical role in the evolution of the structural and functional properties of RE-substituted BiFeO3 thin film materials systems.

A HIGH-RESOLUTION MASS MAP OF GALAXY CLUSTER SUBSTRUCTURE: LensPerfect ANALYSIS OF A1689

We present a strong lensing (SL) mass model of A1689 which resolves substructures an estimated 25 kpc across within the central ∼400 kpc diameter. We achieve this resolution by perfectly reproducing the observed (strongly lensed) input positions of 168 multiple images of 55 knots residing within 135 images of 42 galaxies. Our model makes no assumptions about light tracing mass, yet we reproduce the brightest visible structures with some slight deviations. A1689 remains one of the strongest known lenses on the sky, with an Einstein radius of RE = 470 ± 12 (143+3−4 kpc) for a lensed source at zs = 2. We find that a single Navarro–Frenk–White (NFW) or Sérsic profile yields a good fit simultaneously (with only slight tension) to both our SL mass model and published weak lensing (WL) measurements at larger radius (out to the virial radius). According to this NFW fit, A1689 has a mass of Mvir = 2.0+0.5−0.3 × 1015 M☉ h−170 (M200 = 1.8+0.4−0.3 × 1015 M☉ h−170) within the virial radius rvir = 3.0 ± 0.2 Mpc h−170 (r200 = 2.4+0.1−0.2 Mpc h−170), and a central concentration cvir = 11.5+1.5−1.4 (c200 = 9.2 ± 1.2). Our SL model prefers slightly higher concentrations than previous SL models, bringing our SL + WL constraints in line with other recent derivations. Our results support those of previous studies which find A1689 has either an anomalously large concentration or significant extra mass along the line of sight (perhaps in part due to triaxiality). If clusters are generally found to have higher concentrations than realized in simulations, this could indicate that they formed earlier, perhaps as a result of early dark energy.

PHYSICAL PROPERTIES OF MAIN-BELT COMET P/2005 U1 (READ)

The main-belt comets occupy dynamically asteroidal orbits in the main asteroid belt. Here we present physical observations of the second-known member of this population, P/2005 U1 (Read), which showed vigorous cometary activity from 2005 October 24 to 2005 December 27. Monte Carlo numerical simulations of P/Read's dust emission indicate that the coma and tail are optically dominated by dust particles larger than 10 μm in size with terminal ejection velocities of 0.2-3 m s–1. We estimate P/Read's mass-loss rate during this period to be approximately 0.2 kg s–1, roughly an order of magnitude larger than that calculated for 133P/Elst-Pizarro. We also find that emission likely began at least 2 months prior to P/Read's discovery, though we note this is a lower limit and that earlier start times are possible. Optical colors measured for P/Read while it was active are approximately solar (B – V = 0.63 ± 0.05, V – R = 0.37 ± 0.04, R – I = 0.39 ± 0.04) but are likely to be dominated by coma particles. Observations of P/Read in 2007 when it appears largely inactive show an extremely small nucleus with an absolute magnitude of HR ~ 20.1 ± 0.4, corresponding to an effective radius of re ~ 0.3 km. P/Read's activity is consistent with sublimation-driven dust emission and inconsistent with dust emission due to an impact, though the unusual strength of the 2005 outburst suggests the possibility that it could have been due to the sublimation of a freshly exposed reservoir of volatile material.

Properties of the electron beam in a room-temperature electron beam ion source investigated by position sensitive x-ray detection

The evolution of the charge state distribution inside an electron beam ion source or trap (EBIS/T) is determined by interactions of the electron beam with the ions in the trap region. Hence, detailed information about the electron beam is required for evaluations of spectroscopic and ion extraction measurements performed at EBIS/T facilities. This article presents the results of investigations on the electron beam properties of an ion source of the Dresden EBIS type. For the first time theoretical predictions of the shape of the beam were tested for a noncryogenic EBIS working with low magnetic flux densities provided by permanent magnets. Position and width of the electron beam were measured at different electron energies showing an oscillation in the beam structure. At an energy of E(e)=16 keV and an emission current of I(e)=30 mA the beam is compressed to a radius of r(e)=57 mum (80% current). This refers to an average current density of j(e)=232 A/cm(2).

Primary crystallization of Al–Ni–RE amorphous alloys with different type and content of RE

The primary crystallization of Al 87Ni 6RE 7 and Al 85Ni 6RE 9 (RE = La, Ce, Nd and Y) amorphous alloys was investigated by X-ray diffraction and differential scanning calorimetry. With decreasing the atomic radius of RE, i.e., in an order of La > Ce > Nd > Y, the thermal stability first remains almost unchanged for RE = La and Ce, and then gradually decreases when RE changes through Nd to Y. Meanwhile, the supercooled liquid region gradually enlarges in the Al 85Ni 6RE 9, but changes complicatedly in the Al 87Ni 6RE 7. The primary phase consists of fcc-Al plus metastable phase(s) for RE = La and Ce in the Al 87Ni 6RE 7 or single metastable phase for RE = La, Ce and Y in the Al 85Ni 6RE 9, but only fcc-Al in the other alloys. Except the Al 85Ni 6Nd 9 alloy whose primary crystallization process is interface-controlled in growth, the primary crystallization processes of the other alloys are diffusion-controlled. With increasing the content of RE, the thermal stability, supercooled liquid region and nucleation rate increase. Meanwhile, metastable phases are prone to precipitate.