## Recent Postings from Solar and Stellar

### Measuring the surface magnetic fields of magnetic stars with unresolved Zeeman splitting

High-dispersion, archival spectra of magnetic Ap stars with resolved Zeeman components in Stokes I are used to derive a simple relation that can be utilised to estimate the mean surface field strengths of stars with v sin i > 10 km/s. For each star, the mean surface field, as measured from the observed splitting in Fe II at 6149 A, is compared to the differential broadening of spectral lines with large and small Lande factors in order to produce a relation to estimate the field strengths of magnetic stars with unresolved Zeeman patterns. The method is shown to be reliable for rotational velocities up to about 50 km/s for field strengths down to about 5 kG. These results should allow for better constraints to be placed on the mean surface magnetic fields of Ap stars where Zeeman patterns are unresolved.

### Variations in Abundance Enhancements in Impulsive Solar Energetic-Particle Events and Related CMEs and Flares

We study event-to-event variations in the abundance enhancements of the elements He through Pb for Fe-rich impulsive solar energetic-particle (SEP) events, and their relationship with properties of associated coronal mass ejections (CMEs) and solar flares. Using a least-squares procedure we fit the power-law enhancement of element abundances as a function of their mass-to-charge ratio A/Q to determine both the power and the coronal temperature (which determines Q) in each of 111 impulsive SEP events identified previously. Individual SEP events with the steepest element enhancements, e.g. ~(A/Q)^6, tend to be smaller, lower-fluence events with steeper energy spectra that are associated with B- and C-class X-ray flares, with cooler (~2.5 MK) coronal plasma, and with narrow (<100 deg), slower (<700 km/s) CMEs. On the other hand, higher-fluence SEP events have flatter energy spectra, less-dramatic heavy-element enhancements, e.g. ~(A/Q)^3, and come from somewhat hotter coronal plasma (~3.2 MK) associated with C-, M- and even X-class X-ray flares and with wider CMEs. Enhancements in 3He/4He are uncorrelated with those in heavy elements. However, events with 3He/4He > 0.1 are even more strongly associated with narrow, slow CMEs, with cooler coronal plasma, and with B- and C-class X-ray flares than are other Fe-rich impulsive SEP events with smaller enhancements of 3He.

### The Solar Neighborhood XXXV: Distances to 1404 M Dwarf Systems Within 25 pc in the Southern Sky

We present trigonometric, photometric, and photographic distances to 1748 southern ($\delta \leq$0$^\circ$) M dwarf systems with $\mu \ge$ 0\farcs18 yr$^{-1}$, of which 1404 are believed to lie within 25 parsecs of the Sun. The stars have 6.67 $\leq$ $V_J$ $\leq$ 21.38 and 3.50 $\leq$ ($V_J-K_s$) $\leq$ 9.27, covering the entire M dwarf spectral sequence from M0.0V through M9.5V. This sample therefore provides a comprehensive snapshot of our current knowledge of the southern sky for the nearest M dwarfs that dominate the stellar population of the Galaxy. Roughly one-third of the 1748 systems, each of which has an M dwarf primary, have published high quality parallaxes, including 179 from the RECONS astrometry program. For the remaining systems, we offer photometric distance estimates that have well-calibrated errors. The bulk of these ($\sim$700) are based on new $V_JR_{KC}I_{KC}$ photometry acquired at the CTIO/SMARTS 0.9m telescope, while the remaining 500 primaries have photographic plate distance estimates calculated using SuperCOSMOS $B_JR_{59F}I_{IVN}$ photometry. Confirmed and candidate subdwarfs in the sample have been identified, and a census of companions is included.

### Stimulated neutrino transformation through turbulence on a changing density profile and application to supernovae

We apply the model of stimulated neutrino transitions to neutrinos traveling through turbulence on a non-constant density profile. We describe a method to predict the location of large amplitude transitions and demonstrate the effectiveness of this method by comparing to numerical calculations using a model supernova (SN) profile. The important wavelength scales of turbulence, both those that stimulate neutrino transformations and those that suppress them, are presented and discussed. We then examine the effects of changing the parameters of the turbulent spectrum, specifically the root-mean-square amplitude and cutoff wavelength, and show how the stimulated transitions model offers an explanation for the increase in both the amplitude and number of transitions with large amplitude turbulence, as well as a suppression or absence of transitions for long cutoff wavelengths. The method can also be used to predict the location of transitions between antineutrino states which, in the normal hierarchy we are using, will not undergo Mikheev-Smirnov-Wolfenstein (MSW) transitions. Finally, the stimulated neutrino transitions method is applied to the turbulence derived found in a 2D supernova simulation and explains the minimal observed effect on neutrino oscillations in the simulation as as being due to excessive long wavelength modes suppressing transitions and the absence of modes that fulfill the parametric resonance condition.

### Stimulated neutrino transformation through turbulence on a changing density profile and application to supernovae [Cross-Listing]

We apply the model of stimulated neutrino transitions to neutrinos traveling through turbulence on a non-constant density profile. We describe a method to predict the location of large amplitude transitions and demonstrate the effectiveness of this method by comparing to numerical calculations using a model supernova (SN) profile. The important wavelength scales of turbulence, both those that stimulate neutrino transformations and those that suppress them, are presented and discussed. We then examine the effects of changing the parameters of the turbulent spectrum, specifically the root-mean-square amplitude and cutoff wavelength, and show how the stimulated transitions model offers an explanation for the increase in both the amplitude and number of transitions with large amplitude turbulence, as well as a suppression or absence of transitions for long cutoff wavelengths. The method can also be used to predict the location of transitions between antineutrino states which, in the normal hierarchy we are using, will not undergo Mikheev-Smirnov-Wolfenstein (MSW) transitions. Finally, the stimulated neutrino transitions method is applied to the turbulence derived found in a 2D supernova simulation and explains the minimal observed effect on neutrino oscillations in the simulation as as being due to excessive long wavelength modes suppressing transitions and the absence of modes that fulfill the parametric resonance condition.

### Heavy metals in a light white dwarf: Abundances of the metal-rich, extremely low-mass GALEX J1717+6757

Using the Hubble Space Telescope, we detail the first abundance analysis enabled by far-ultraviolet spectroscopy of a low-mass (~0.19 Msun) white dwarf (WD), GALEX J1717+6757, which is in a 5.9-hr binary with a fainter, more-massive companion. We see absorption from nine metals, including roughly solar abundances of Ca, Fe, Ti, and P. We detect a significantly sub-solar abundance of C, and put upper limits on N and O that are also markedly sub-solar. Updated diffusion calculations indicate that all metals should settle out of the atmosphere of this 14,900 K, log(g) = 5.67 WD in the absence of radiative forces in less than 20 yr, orders of magnitude faster than the cooling age of hundreds of Myr. We demonstrate that ongoing accretion of rocky material that is often the cause of atmospheric metals in isolated, more massive WDs is unlikely to explain the observed abundances in GALEX J1717+6757. Using new radiative levitation calculations, we determine that radiative forces can counteract diffusion and support many but not all of the elements present in the atmosphere of this WD; radiative levitation cannot, on its own, explain all of the observed abundance patterns, and additional mechanisms such as rotational mixing may be required. Finally, we detect both primary and secondary eclipses using ULTRACAM high-speed photometry, which we use to constrain the low-mass WD radius and rotation rate as well as update the ephemeris from the discovery observations of this WD+WD binary.

### Global temperatures and sunspot numbers. Are they related? Yes, but non linearly. A reply to Gil-Alana et al. (2014) [Cross-Listing]

Gil-Alana et al. (Physica A: 396, 42-50, 2014) compared the sunspot number record and the temperature record and found that they differ: the sunspot number record is characterized by a dominant 11-year cycle while the temperature record appears to be characterized by a singularity or pole in the spectral density function at the zero frequency. Consequently, they claimed that the two records are characterized by substantially different statistical fractional models and rejected the hypothesis that sun influences significantly global temperatures. I show that: (1) the "singularity" or "pole" in the spectral density function of the global surface temperature at the "zero" frequency does not exist – it is a typical misinterpretation that discrete power spectra of non-stationary signals can suggest; (2) appropriate continuous periodograms clarify the issue and also show a signature of the 11-year solar cycle (amplitude <0.1 K), which since 1850 has an average period of about 10.4 year, and of many other natural oscillations; (3) the solar signature in the surface temperature record can be recognized only using specific techniques of analysis that take into account non-linearity and filtering of the multiple climate change contributions; (4) the post 1880-year temperature warming trend cannot be compared or studied against the sunspot record and its 11-year cycle, but requires solar proxy models showing short and long scale oscillations plus the contribution of anthropogenic forcings, as done in the literature. Multiple evidences suggest that global temperatures and sunspot numbers are quite related to each other at multiple time scales through complex and non-linear processes. Finally, I show that the prediction of a semi-empirical model for the global temperature based on astronomical oscillations and anthropogenic forcing proposed by Scafetta since 2009 has up to date been successful.

### Galactic globular cluster 47 Tucanae: new ties between the chemical and dynamical evolution of globular clusters?

It is generally accepted today that Galactic globular clusters (GGCs) consist of at least two generations of stars that are different in their chemical composition and perhaps age. However, knowledge about the kinematical properties of these stellar generations, which may provide important information for constraining evolutionary scenarios of the GGCs, is still limited. We therefore study the connections between chemical and kinematical properties of different stellar generations in the Galactic globular cluster 47 Tuc. To achieve this goal, we used abundances of Li, O, and Na determined in 101 main sequence turn-off (TO) stars with the aid of 3D hydrodynamical model atmospheres and NLTE abundance analysis methodology. We divided our sample TO stars into three groups according to their position in the [Li/Na]-[Na/O] plane to study their spatial distribution and kinematical properties. We find that there are statistically significant radial dependencies of lithium and oxygen abundances, A(Li) and A(O), as well as that of [Li/Na] abundance ratio. Our results show that first-generation stars are less centrally concentrated and dynamically hotter than stars belonging to subsequent generations. We also find a significant correlation between the velocity dispersion and O and Na abundance, and between the velocity dispersion and the [Na/O] abundance ratio.

### IC348-SMM2E: a Class 0 proto-brown dwarf candidate forming as a scaled-down version of low-mass stars

We report on Submillimeter Array observations of the 870 micron continuum and CO(3-2), 13CO(2-1) and C18O(2-1) line emission of a faint object, SMM2E, near the driving source of the HH797 outflow in the IC348 cluster. The continuum emission shows an unresolved source for which we estimate a mass of gas and dust of 30 Mjup, and the CO(3-2) line reveals a compact bipolar outflow centred on SMM2E, and barely seen also in 13CO(2-1). In addition, C18O(2-1) emission reveals hints of a possible rotating envelope/disk perpendicular to the outflow, for which we infer a dynamical mass of ~16 Mjup. In order to further constrain the accreted mass of the object, we gathered data from Spitzer, Herschel, and new and archive submillimetre observations, and built the Spectral Energy Distribution (SED). The SED can be fitted with one single modified black-body from 70 micron down to 2.1 cm, using a dust temperature of ~24 K, a dust emissivity index of 0.8, and an envelope mass of ~35 Mjup. The bolometric luminosity is 0.10 Lsun, and the bolometric temperature is 35 K. Thus, SMM2E is comparable to the known Class 0 objects in the stellar domain. An estimate of the final mass indicates that SMM2E will most likely remain substellar, and the SMM2E outflow force matches the trend with luminosity known for young stellar objects. Thus, SMM2E constitutes an excellent example of a Class 0 proto-brown dwarf candidate which forms as a scaled-down version of low-mass stars. Finally, SMM2E seems to be part of a wide (~2400 AU) multiple system of Class 0 sources.

### Near-infrared line identification in type Ia supernovae during the transitional phase

We present near-infrared synthetic spectra of a delayed-detonation hydrodynamical model and compare them to observed spectra of four normal type Ia supernovae ranging from day +56.5 to day +85. This is the epoch during which supernovae are believed to be undergoing the transition from the photospheric phase, where spectra are characterized by line scattering above an optically thick photosphere, to the nebular phase, where spectra consist of optically thin emission from forbidden lines. We find that most spectral features in the near-infrared can be accounted for by permitted lines of Fe II and Co II. In addition, we find that [Ni II] fits the emission feature near 1.98 {\mu}m, suggesting that a substantial mass of 58Ni exists near the center of the ejecta in these objects, arising from nuclear burning at high density. A tentative identification of Mn II at 1.15 {\mu}m may support this conclusion as well.

### On the Class II Methanol Maser Periodic Variability due to the Rotating Spiral Shocks in the Gaps of Disks Around Young Binary Stars

We argue that the periodic variability of Class II methanol masers can be explained by variations of the dust temperature in the accretion disk around proto-binary star with at least one massive component. The dust temperature variations are caused by rotation of hot and dense material of the spiral shock wave in the disk central gap. The aim of this work is to show how different can be the Class II methanol maser brightness in the disk during the Moment of Maximum Illumination by the Spiral Shock material (hereafter MMISS) and the Moment when the disk is Illuminated by the Stars Only (MISO). We used the code CLOUDY (v13.02) to estimate physical conditions in the flat disk in the MISO and the MMISS. Model physical parameters of the disk were then used to estimate the brightness of 6.7, 9.9, 12.1 and 107 GHz masers at different impact parameters $p$ using LVG approximation. It was shown that the strong masers experience considerable brightness increase during the MMISS with respect to MISO. There can happen both flares and dips of the 107 GHz maser brightness under the MMISS conditions, depending on the properties of the system. The brightest 9.9 GHz masers in the MMISS are situated at the greater $p$ than the strong 6.7, 12.1 and 107 GHz masers that are situated at $p<200$ AU. The brightness of 9.9 GHz maser in the MMISS suppressed at $p<200$ AU and increase at $p>200$ AU.

### Stokes $IQUV$ magnetic Doppler imaging of Ap stars - III. Next generation chemical abundance mapping of Alpha 2 CVn

In a previous paper we presented an updated magnetic field map for the chemically peculiar star Alpha 2 CVn using ESPaDOnS and Narval time-resolved high-resolution Stokes $IQUV$ spectra. In this paper we focus on mapping various chemical element distributions on the surface of Alpha 2 CVn. With the new magnetic field map and new chemical abundance distributions we can investigate the interplay between the chemical abundance structures and the magnetic field topology on the surface of Alpha 2 CVn. Previous attempts at chemical abundance mapping of Alpha 2 CVn relied on lower resolution data. With our high resolution (R=65,000) dataset we present nine chemical abundance maps for the elements O, Si, Cl, Ti, Cr, Fe, Pr, Nd and Eu. We also derive an updated magnetic field map from Fe and Cr lines in Stokes $IQUV$ and O and Cl in Stokes $IV$. These new maps are inferred from line profiles in Stokes $IV$ using the magnetic Doppler imaging code Invers10. We examine these new chemical maps and investigate correlations with the magnetic topology of Alpha 2 CVn. We show that chemical abundance distributions vary between elements, with two distinct groups of elements; one accumulates close to the negative part of the radial field, whilst the other group shows higher abundances located where the radial magnetic field is on the order of 2 kG regardless of the polarity of the radial field component. We compare our results with previous works which have mapped chemical abundance structures of Ap stars. With the exception of Cr and Fe, we find no clear trend between what we reconstruct and other mapping results. We also find a lack of agreement with theoretical predictions. This suggests that there is a gap in our theoretical understanding of the formation of horizontal chemical abundance structures and the connection to the magnetic field in Ap stars.

### Radio emission of magnetars driven by the quasi-linear diffusion

In the present paper we study the possibility of generation of electromagnetic waves in the magnetospheres of radio magnetars by means of the quasi-linear diffusion (QLD). Considering the magnetosphere composed of the so-called beam and the plasma components respectively, we argue that the frozen-in condition will inevitably lead to the generation of the unstable cyclotron modes. These modes, via the QLD, will in turn influence the particle distribution function, leading to certain values of the pitch angles, thus to an efficient synchrotron mechanism, producing radio photons. We show that for three known radio magnetars the QLD might be a realistic mechanism for producing photons in the radio band.

### Modulating the magnetosphere of magnetars by internal magneto-elastic oscillations

We couple internal torsional, magneto-elastic oscillations of highly magnetized neutron stars (magnetars) to their magnetospheres. The corresponding axisymmetric perturbations of the external magnetic field configuration evolve as a sequence of linear, force-free equilibria that are completely determined by the background magnetic field configuration and by the perturbations of the magnetic field at the surface. The perturbations are obtained from simulations of magneto-elastic oscillations in the interior of the magnetar. While such oscillations can excite travelling Alfv\’en waves in the exterior of the star only in a very limited region close to the poles, they still modulate the near magnetosphere by inducing a time-dependent twist between the foot-points of closed magnetic field lines that exit the star at a polar angle $\gtrsim 0.19\,$rad. Moreover, we find that for a dipole-like background magnetic field configuration the magnetic field modulations in the magnetosphere, driven by internal oscillations, can only be symmetric with respect to the equator. This is in agreement with our previous findings, where we interpreted the observed quasi-periodic oscillations in the X-ray tail of magnetar bursts as driven by the family of internal magneto-elastic oscillations with symmetric magnetic field perturbations.

### Discovery of extremely lead-rich subdwarfs: does heavy metal signal the formation of subdwarf B stars?

Hot subdwarfs represent a group of low-mass helium-burning stars formed through binary-star interactions and include some of the most chemically-peculiar stars in the Galaxy. Stellar evolution theory suggests that they should have helium-rich atmospheres but, because radiation causes hydrogen to diffuse upwards, a majority are extremely helium poor. Questions posed include: when does the atmosphere become chemically stratified and at what rate? The existence of several helium-rich subdwarfs suggests further questions; are there distinct subgroups of hot subdwarf, or do hot subdwarfs change their surface composition in the course of evolution? Recent analyses have revealed remarkable surface chemistries amongst the helium-rich subgroup. In this paper, we analyse high-resolution spectra of nine intermediate helium-rich hot subdwarfs. We report the discovery that two stars, HE 2359-2844 and HE 1256-2738, show an atmospheric abundance of lead which is nearly ten thousand times that seen in the Sun. This is measured from optical Pb IV absorption lines never previously seen in any star. The lead abundance is ten to 100 times that measured in normal hot subdwarf atmospheres from ultraviolet spectroscopy. HE 2359-2844 also shows zirconium and yttrium abundances similar to those in the zirconium star LS IV-14 116. The new discoveries are interpreted in terms of heavily stratified atmospheres and the general picture of a surface chemistry in transition from a new-born helium-rich subdwarf to a normal helium-poor subdwarf.

### Narrow-Band Imaging System for the Multi-application Solar Telescope at Udaipur Solar Observatory: Characterization of Lithium Niobate Etalons

Multi-application Solar Telescope is a 50 cm off-axis Gregorian telescope that has been installed at the lake site of Udaipur Solar Observatory. For quasi-simultaneous photospheric and chromospheric observations, a narrow-band imager has been developed as one of the back-end instruments for this telescope. Narrow-band imaging is achieved using two lithium niobate Fabry-Perot etalons working in tandem as a filter. This filter can be tuned to different wavelengths by changing either voltage, tilt or temperature of the etalons. To characterize the etalons, a Littrow spectrograph was set up, in conjunction with a 15 cm Carl Zeiss Coud\’e solar telescope. The etalons were calibrated for the solar spectral lines FeI 6173 {\AA}, and CaII 8542 {\AA}. In this work, we discuss the characterization of the Fabry-Perot etalons, specifically the temperature and voltage tuning of the system for the spectral lines proposed for observations. We present the details of the calibration set-up and various tuning parameters. We also present solar images obtained using the system parameters. We also present solar images obtained using the system.

### Optical BVRI Photometry of Common Proper Motion F/G/K+M Wide Separation Binaries

We present optical (BVRI) photometric measurements of a sample of 76 common proper motion wide separation main sequence binary pairs. The pairs are composed of a F-, G-, or K-type primary star and an M-type secondary. The sample is selected from the revised NLTT catalog and the LSPM catalog. The photometry is generally precise to 0.03 mag in all bands. We separate our sample into two groups, dwarf candidates and subdwarf candidates, using the reduced proper motion (RPM) diagram constructed with our improved photometry. The M subdwarf candidates in general have larger $V-R$ colors than the M dwarf candidates at a given $V-I$ color. This is consistent with an average metallicity difference between the two groups, as predicted by the PHOENIX/BT-Settl models. The improved photometry will be used as input into a technique to determine the metallicities of the M-type stars.

### The cosmological Lithium problem outside the Galaxy: the Sagittarius globular cluster M54

The cosmological Li problem is the observed discrepancy between Li abundance, A(Li), measured in Galactic dwarf, old and metal-poor stars (traditionally assumed to be equal to the initial value A(Li)_0), and that predicted by standard Big Bang Nucleosynthesis calculations (A(Li)_{BBN}). Here we attack the Li problem by considering an alternative diagnostic, namely the surface Li abundance of red giant branch stars that in a colour magnitude diagram populate the region between the completion of the first dredge-up and the red giant branch bump. We obtained high-resolution spectra with the FLAMES facility at the Very Large Telescope for a sample of red giants in the globular cluster M54, belonging to the Sagittarius dwarf galaxy. We obtain A(Li)=+0.93+-0.11 dex, translating — after taking into account the dilution due to the dredge up– to initial abundances (A(Li)_0) in the range 2.35–2.29 dex, depending on whether or not atomic diffusion is considered. This is the first measurement of Li in the Sagittarius galaxy and the more distant estimate of A(Li)_0 in old stars obtained so far. The A(Li)_0 estimated in M54 is lower by ~0.35 dex than A(Li)_{BBN}, hence incompatible at a level of ~3sigma. Our result shows that this discrepancy is a universal problem concerning both the Milky Way and extra-galactic systems. Either modifications of BBN calculations, or a combination of atomic diffusion plus a suitably tuned additional mixing during the main sequence, need to be invoked to solve the discrepancy.

### Three Ancient Halo Subgiants: Precise Parallaxes, Compositions, Ages, and Implications for Globular Clusters

The most accurate ages for the oldest stars are those obtained for nearby halo subgiants, because they depend almost entirely on just the measured parallaxes and absolute oxygen abundances. In this study, we have used the Fine Guidance Sensors on the Hubble Space Telescope to determine trigonometric parallaxes, with precisions of 2.1% or better, for the Population II subgiants HD 84937, HD 132475, and HD 140283. High quality spectra have been used to derive their surface abundances of O, Fe, Mg, Si, and Ca, which are assumed to be 0.1-0.15 dex less than their initial abundances due to the effects of diffusion. Comparisons of isochrones with the three subgiants on the $(\log\,T_{\rm eff}, M_V)$-diagram yielded ages of $12.08 \pm 0.14, 12.56 \pm 0.46$, and $14.27 \pm 0.38$ Gyr for HD 84937, HD 132475, and HD 140283, in turn, where each error bar includes only the parallax uncertainty. The total uncertainty is estimated to be $\sim\pm 0.8$ Gyr (larger in the case of the near-turnoff star HD 84937). Although the age of HD 140283 is greater than the age of the universe as inferred from the cosmic microwave background by $\sim$ 0.4-0.5 Gyr, this discrepancy is at a level of $< 1\,\sigma$. Nevertheless, the first Population II stars apparently formed very soon after the Big Bang. (Stellar models that neglect diffusive processes seem to be ruled out as they would predict that HD 140283 is $\sim 1.5$ Gyr older than the universe.) The halo field subgiants appear to be older than globular clusters of similar metallicities: if distances close to those implied by the RR Lyrae standard candle are assumed, M92 and M5 are younger than HD 140283 and HD 132475 by $\sim 1.5$ and $\sim 1.0$ Gyr, respectively.

### Galactic astronomy with AO: Nearby star clusters and moving groups

Observations of Galactic star clusters and objects in nearby moving groups recorded with Adaptive Optics (AO) systems on Gemini South are discussed. These include observations of open and globular clusters with the GeMS system, and high Strehl L’ observations of the moving group member Sirius obtained with NICI. The latter data fail to reveal a brown dwarf companion with a mass in excess of 0.02 solar in an 18 x 18 arcsec^2 area around Sirius A. Potential future directions for AO studies of nearby star clusters and groups with systems on large telescopes are also presented.

### Supernovae at the cosmic dawn

Modern cosmological simulations predict that the first generation of stars formed with a mass scale around 100 solar masses about 300-400 million years after the Big Bang. When the first stars reached the end of their lives, many of them might have died as energetic supernovae that could have significantly affected the early Universe via injecting large amounts of energy and metals into the primordial intergalactic medium. In this paper, we review the current models of the first supernovae by discussing on the relevant background physics, computational methods, and the latest results.

### Impact of Population~III binaries on early cosmic evolution

We present the results of the stellar feedback from Pop~III binaries by employing improved, more realistic Pop~III evolutionary stellar models. To facilitate a meaningful comparison, we consider a fixed mass of 60 solar masses (Msun) incorporated in Pop~III stars, either contained in a single star, or split up in binary stars of 30 Msun each or an asymmetric case of one 45 Msun and one 15 Msun star. Whereas the sizes of the resulting HII regions are comparable across all cases, the HeIII regions around binary stars are significantly smaller than that of the single star. Consequently, the He$^{+}$ 1640 angstrom recombination line is expected to become much weaker. Supernova feedback exhibits great variety due to the uncertainty in possible explosion pathways. If at least one of the component stars dies as a hypernova about ten times more energetic than conventional core-collapse supernovae, the gas inside the host minihalo is effectively blown out, chemically enriching the intergalactic medium (IGM) to an average metallicity of $10^{-4}-10^{-3}$ solar metallicity (Zsun), out to $\sim 2$ kpc. The single star, however, is more likely to collapse into a black hole, accompanied by at most very weak explosions. The effectiveness of early chemical enrichment would thus be significantly reduced, in difference from the lower mass binary stars, where at least one component is likely to contribute to heavy element production and dispersal. Important new feedback physics is also introduced if close binaries can form high-mass x-ray binaries, leading to the pre-heating and -ionization of the IGM beyond the extent of the stellar HII regions.

### The origin of the 'local' 1/4 keV X-ray flux in both charge exchange and a hot bubble

The Solar neighborhood is the closest and most easily studied sample of the Galactic interstellar medium, an understanding of which is essential for models of star formation and galaxy evolution. Observations of an unexpectedly intense diffuse flux of easily-absorbed 1/4 keV X rays, coupled with the discovery that interstellar space within ~100 pc of the Sun is almost completely devoid of cool absorbing gas led to a picture of a "local cavity" filled with X-ray emitting hot gas dubbed the local hot bubble. This model was recently upset by suggestions that the emission could instead be produced readily within the solar system by heavy solar wind ions charge exchanging with neutral H and He in interplanetary space, potentially removing the major piece of evidence for the existence of million-degree gas within the Galactic disk. Here we report results showing that the total solar wind charge exchange contribution is 40% +/- 5% (stat) +/- 5% (sys) of the 1/4 keV flux in the Galactic plane. The fact that the measured flux is not dominated by charge exchange supports the notion of a million-degree hot bubble of order 100 pc extent surrounding the Sun.

### Finding $\eta$ Car Analogs in Nearby Galaxies Using Spitzer: II. Identification of An Emerging Class of Extragalactic Self-Obscured Stars

Understanding the late-stage evolution of the most massive stars such as $\eta$ Carinae is challenging because no true analogs of $\eta$ Car have been clearly identified in the Milky Way or other galaxies. In Khan et. al. (2013), we utilized Spitzer IRAC images of $7$ nearby ($\lesssim4$ Mpc) galaxies to search for such analogs, and found $34$ candidates with flat or red mid-IR spectral energy distributions. Here, in Paper II, we present our characterization of these candidates using multi-wavelength data from the optical through the far-IR. Our search detected no true analogs of $\eta$ Car, which implies an eruption rate that is a fraction $0.01\lesssim F \lesssim 0.19$ of the ccSN rate. This is roughly consistent with each $M_{ZAMS} \gtrsim 70M_\odot$ star undergoing $1$ or $2$ outbursts in its lifetime. However, we do identify a significant population of $18$ lower luminosity $\left(\log(L/L_\odot)\simeq5.5-6.0\right)$ dusty stars. Stars enter this phase at a rate that is fraction $0.09 \lesssim F \lesssim 0.55$ of the ccSN rate, and this is consistent with all $25 < M_{ZAMS} < 60M_\odot$ stars undergoing an obscured phase at most lasting a few thousand years once or twice. These phases constitute a negligible fraction of post-main sequence lifetimes of massive stars, which implies that these events are likely to be associated with special periods in the evolution of the stars. The mass of the obscuring material is of order $\sim M_\odot$, and we simply do not find enough heavily obscured stars for theses phases to represent more than a modest fraction ($\sim 10\%$ not $\sim 50\%$) of the total mass lost by these stars. In the long term, the sources that we identified will be prime candidates for detailed physical analysis with JWST.