9 research outputs found
Physics of Solar Prominences: I - Spectral Diagnostics and Non-LTE Modelling
This review paper outlines background information and covers recent advances
made via the analysis of spectra and images of prominence plasma and the
increased sophistication of non-LTE (ie when there is a departure from Local
Thermodynamic Equilibrium) radiative transfer models. We first describe the
spectral inversion techniques that have been used to infer the plasma
parameters important for the general properties of the prominence plasma in
both its cool core and the hotter prominence-corona transition region. We also
review studies devoted to the observation of bulk motions of the prominence
plasma and to the determination of prominence mass. However, a simple inversion
of spectroscopic data usually fails when the lines become optically thick at
certain wavelengths. Therefore, complex non-LTE models become necessary. We
thus present the basics of non-LTE radiative transfer theory and the associated
multi-level radiative transfer problems. The main results of one- and
two-dimensional models of the prominences and their fine-structures are
presented. We then discuss the energy balance in various prominence models.
Finally, we outline the outstanding observational and theoretical questions,
and the directions for future progress in our understanding of solar
prominences.Comment: 96 pages, 37 figures, Space Science Reviews. Some figures may have a
better resolution in the published version. New version reflects minor
changes brought after proof editin
Characterization of the Praesepe Star Cluster by Photometry and Proper Motions with 2MASS, PPMXL, and Pan-STARRS
Membership identification is the first step in determining the properties of a star cluster. Low-mass members in particular could be used to trace the dynamical history, such as mass segregation, stellar evaporation, or tidal stripping, of a star cluster in its Galactic environment. We identified member candidates of the intermediate-age Praesepe cluster (M44) with stellar masses ~0.11-2.4 M ☉, using Panoramic Survey Telescope And Rapid Response System and Two Micron All Sky Survey photometry, and PPMXL proper motions. Within a sky area of 3° radius, 1040 candidates are identified, of which 96 are new inclusions. Using the same set of selection criteria on field stars, an estimated false positive rate of 16% was determined, suggesting that 872 of the candidates are true members. This most complete and reliable membership list allows us to favor the BT-Settl model over other stellar models. The cluster shows a distinct binary track above the main sequence, with a binary frequency of 20%-40%, and a high occurrence rate of similar mass pairs. The mass function is consistent with that of the disk population but shows a deficit of members below 0.3 solar masses. A clear mass segregation is evidenced, with the lowest-mass members in our sample being evaporated from this disintegrating cluster
GALEX AND PAN-STARRS1 DISCOVERY OF SN IIP 2010aq: THE FIRST FEW DAYS AFTER SHOCK BREAKOUT IN A RED SUPERGIANT STAR
We present the early UV and optical light curve of Type IIP supernova (SN)
2010aq at z=0.0862, and compare it to analytical models for thermal emission
following SN shock breakout in a red supergiant star. SN 2010aq was discovered
in joint monitoring between the Galaxy Evolution Explorer (GALEX) Time Domain
Survey (TDS) in the NUV and the Pan-STARRS1 Medium Deep Survey (PS1 MDS) in the
g, r, i, and z bands. The GALEX and Pan-STARRS1 observations detect the SN less
than 1 day after shock breakout, measure a diluted blackbody temperature of
31,000 +/- 6,000 K 1 day later, and follow the rise in the UV/optical light
curve over the next 2 days caused by the expansion and cooling of the SN
ejecta. The high signal-to-noise ratio of the simultaneous UV and optical
photometry allows us to fit for a progenitor star radius of 700 +/- 200 R_sun,
the size of a red supergiant star. An excess in UV emission two weeks after
shock breakout compared to SNe well fitted by model atmosphere-code synthetic
spectra with solar metallicity, is best explained by suppressed line blanketing
due to a lower metallicity progenitor star in SN 2010aq. Continued monitoring
of PS1 MDS fields by the GALEX TDS will increase the sample of early UV
detections of Type II SNe by an order of magnitude, and probe the diversity of
SN progenitor star properties.Comment: 4 pages, 3 color figures. Accepted for publication in ApJ Letters,
corrections from proofs adde
The Pan-STARRS1 Database and Data Products
This paper describes the organization of the database and the catalog data products from the Pan-STARRS1 3π Steradian Survey. The catalog data products are available in the form of an SQL-based relational database from MAST, the Mikulski Archive for Space Telescopes at STScI. The database is described in detail, including the construction of the database, the provenance of the data, the schema, and how the database tables are related. Examples of queries for a range of science goals are included