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The Planck Cold Clump G108.37-01.06: A Site of Complex Interplay between H II Regions, Young Clusters, and Filaments
Jose, Jessy; Samal, Manash R.; Dutta, Somnath +1 more
The Planck Galactic Cold Clumps (PGCCs) are possible representations of the initial conditions and very early stages of star formation. With the objective of understanding better the star and star cluster formation, we probe the molecular cloud associated with PGCC G108.37-01.06 (hereafter PG108.3), which can be traced in a velocity range of -57 t…
Neutral Helium Triplet Spectroscopy of Quiescent Coronal Rain with Sensitivity Estimates for Spectropolarimetric Magnetic Field Diagnostics
Schad, Thomas A.
On account of its polarizability and magnetic field sensitivity, as well as the role of neutral helium in partially ionized solar environments, the neutral helium triplet (orthohelium) system provides important, yet underutilized, diagnostics of solar coronal rain. This work describes off-limb observations of coronal rain in NOAA Active Region 124…
The Origin of High-velocity Stars from Gaia and LAMOST
Shi, Jianrong; Chen, Yuqin; Ma, Jun +4 more
Based on the second Gaia data release and spectroscopy from the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) Data Release 5, we define the high-velocity (HiVel) stars sample as those stars with v gc > 0.85v esc, and derived the final sample of 24 HiVel stars with stellar astrometric parameters and rad…
A Search for Black Hole Microlensing Signatures in Globular Cluster NGC 6656 (M22)
Anderson, J.; Casertano, S.; Kains, N. +3 more
We report the results of a study aiming to detect signs of astrometric microlensing caused by an intermediate-mass black hole (IMBH) in the center of globular cluster M22 (NGC 6656). We used archival data from the Hubble Space Telescope (HST) taken between 1995 and 2014 to derive long-baseline astrometric time series for stars near the center of t…
SETI with Gaia: The Observational Signatures of Nearly Complete Dyson Spheres
Zackrisson, Erik; Korn, Andreas J.; Wehrhahn, Ansgar +1 more
A star enshrouded in a Dyson sphere with a high covering fraction may manifest itself as an optically subluminous object with a spectrophotometric distance estimate significantly in excess of its parallax distance. Using this criterion, the Gaia mission will in coming years allow for Dyson sphere searches that are complementary to searches based o…
Three-dimensional Magnetic Reconnection Triggering an X-class Confined Flare in Active Region 12192
Hou, Yijun; Li, Ting; Yang, Shuhong +1 more
We present an extensive analysis of the X2.0-class confined flare on 2014 October 27 in the great active region, AR 12192, observed by the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory. The slipping motion of the substructures within the negative-polarity flare ribbon (R1) and continual reconnection-induced flows during …
The Effect of Spots on the Luminosity Spread of the Pleiades
Herczeg, Gregory J.; Guo, Zhen; Gully-Santiago, Michael
Cool spots on the surface of magnetically active stars modulate their observed brightnesses and temperatures, thereby affecting the stellar locus on the H-R diagram. Recent high-precision space-based photometric surveys reveal the rotational modulation from spots on stars in young clusters, including K2 monitoring of the 125 Myr old Pleiades clust…
Models of the Mass-ejection Histories of Pre-planetary Nebulae. II. The Formation of Minkowski’s Butterfly and its Proboscis in M2-9
Frank, Adam; Balick, Bruce; Liu, Baowei +1 more
M2-9, or the “Minkowski’s Butterfly,” is one of the most iconic outflow sources from an evolved star. In this paper we present a hydrodynamic model of M2-9 in which the nebula is formed and shaped by a steady, low-density (“light”), mildly collimated “spray” of gas injected at 200 km s-1 that interacts with a far denser, intrinsically s…
Imaging Spectroscopy of Ionized Gaseous Nebulae around Optically Faint AGNs at Redshift z ∼ 2
Steidel, Charles C.; Law, David R.; Rudie, Gwen C. +3 more
We present Keck/OSIRIS laser guide-star assisted adaptive optics (LGSAO) integral-field spectroscopy of [O III] λ5007 nebular emission from 12 galaxies hosting optically faint ({ \mathcal R } = 20-25 ν {L}ν ∼ {10}44-{10}46 erg s-1) active galactic nuclei (AGNs) at redshift z ∼ 2-3. In combination with de…
Variability of Disk Emission in Pre-main-sequence and Related Stars. IV. Investigating the Structural Changes in the Inner Disk Region of MWC 480
Bayyari, Ammar; Russell, Ray W.; Sitko, Michael L. +8 more
We present five epochs of near-IR observations of the protoplanetary disk around MWC 480 (HD 31648) obtained with the SpeX spectrograph on NASA’s Infrared Telescope Facility between 2007 and 2013, inclusive. Using the measured line fluxes in the Pa β and Br γ lines, we found the mass accretion rates to be (1.26-2.30) × 10-7 M ⊙