509 research outputs found
Mirror, Mirror, Help Me Like My Body: Examining a Body Image Media Campaign
Body image is a concern for many individuals but especially for women. Few body image interventions focus beyond the individual and attempt to reach a larger population. A media campaign was developed using the Social Marketing Model and implemented on a university campus to help women recognize conversations and ideas that reinforce negative body image concepts. Details about the development and implementation of the media campaign are reviewed. Follow-up assessment revealed that almost 60% (n = 194) of women surveyed saw the materials. Many responded favorably to the campaign’s impact. Buscards were viewed most frequently, indicating a potential promotion strategy for future health campaigns. Implications for future interventions and recommendations for practitioners are discussed
The White Dwarfs within 25 Parsecs of the Sun: Kinematics and Spectroscopic Subtypes
We present the fractional distribution of spectroscopic subtypes, range and
distribution of surface temperatures, and kinematical properties of the white
dwarfs within 25pc of the sun. There is no convincing evidence of halo white
dwarfs in the total 25 pc sample of 224 white dwarfs. There is also little to
suggest the presence of genuine thick disk subcomponent members within 25
parsecs. It appears that the entire 25 pc sample likely belong to the thin
disk. We also find no significant kinematic differences with respect to
spectroscopic subtypes. The total DA to non-DA ratio of the 25 pc sample is
1.8, a manifestation of deepening envelope convection which transforms DA stars
with sufficiently thin H surface layers into non-DAs. We compare this ratio
with the results of other studies. We find that at least 11% of the white
dwarfs within 25 parsecs of the sun (the DAZ and DZ stars) have photospheric
metals that likely originate from accretion of circumstellar material (debris
disks) around them. If this interpretation is correct, then it suggests the
possibility that a similar percentage have planets, asteroid-like bodies or
debris disks orbiting them. Our volume-limited sample reveals a pileup of DC
white dwarfs at the well-known cutoff in DQ white dwarfs at Tef about 6000K.
Mindful of small number statistics, we speculate on its possible evolutionary
significance. We find that the incidence of magnetic white dwarfs in the 25 pc
sample is at least 8%, in our volume-limited sample, dominated by cool white
dwarfs. We derive approximate formation rates of DB and DQ degenerates and
present a preliminary test of the evolutionary scenario that all cooling DB
stars become DQ white dwarfs via helium convective dredge-up with the diffusion
tail of carbon extending upward from their cores.Comment: Accepted for publication in The Astronomical Journa
Tracers of chromospheric structure. I. CaII HK emission distribution of 13000 F, G and K stars in SDSS DR7 spectroscopic sample
We present chromospheric activity index measurements for over
13,000 F, G and K disk stars with high signal-to-noise ratio ( 60) spectra
in the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) spectroscopic
sample. A parameter S is defined as the difference between
and a `zero' emission line fitted by several of the most inactive stars. The
indices of subgiant stars tend to be much lower than dwarfs, which
provide a way to distinguish dwarfs and giants with relatively low resolution
spectra. Cooler stars are generally more active and display a larger scatter
than hotter stars. Stars associated with the thick disk are in general less
active than those of the thin disk. The fraction of K dwarfs that are active
drops with vertical distance from the Galactic plane. Metallicity affects
measurements differently among F, G and K dwarfs in this sample.
Using the open clusters NGC 2420, M67 and NGC6791 as calibrations, ages of most
field stars in this SDSS sample range from 3-8 Gyr.Comment: 9 pages, 11 figures, AJ, 2013, 145, 14
LP 400-22, A very low-mass and high-velocity white dwarf
We report the identification of LP 400-22 (WD 2234+222) as a very low-mass
and high-velocity white dwarf. The ultraviolet GALEX and optical photometric
colors and a spectral line analysis of LP 400-22 show this star to have an
effective temperature of 11080+/-140 K and a surface gravity of log g =
6.32+/-0.08. Therefore, this is a helium core white dwarf with a mass of 0.17
M_solar. The tangential velocity of this white dwarf is 414+/-43 km/s, making
it one of the fastest moving white dwarfs known. We discuss probable
evolutionary scenarios for this remarkable object.Comment: accepted for publication in ApJ Letters, made minor correction
Comparative study of simulated and observed blended light curves for unambiguous stellar rotation period determinations
Gyrochronology postulates that the age of stars similar in mass to our Sun can be approximated based on their rotational period. With this in mind, determining accurate rotation periods using photometry data from missions such as Kepler, K2, and TESS is vital for accurate stellar age estimates. Blended light curves pose a particular problem: When conducting simple aperture photometry, neighboring targets can taint the resulting light curve. In most cases, this issue makes the data unusable for unambiguous determination of stellar rotation periods. In this poster, we outline our research project, which aims to provide a solution to the issue of blended light curves. The project consists of computing a grid of simulated blended light curves and comparing them to observed blended photometric data from Kepler, K2, and TESS. Simulations will be computed using Butterpy, a Python package that yields the light curve of a particular model of starspots evolving through the stellar surface. We expect to quantitatively match any simulation from the grid to any of the blended light curves in our sample. Success in the project results will significantly impact other fields of astronomy that also use photometric data by facilitating a new collection of previously unusable data
70 DA White Dwarfs Identified in Lamost Pilot Survey
We present a spectroscopically identified catalog of 70 DA white dwarfs (WDs) from the LAMOST pilot survey. Thirty-five are found to be new identifications after cross-correlation with the Eisenstein et al. and Villanova catalogs. The effective temperature and gravity of these WDs are estimated by Balmer lines fitting. Most of them are hot WDs. The cooling times and masses of these WDs are estimated by interpolation in theoretical evolution tracks. The peak of the mass distribution is found to be ∼0.6M, which is consistent with prior work in the literature. The distances of these WDs are estimated using the method of synthetic spectral distances. All of these WDs are found to be in the Galactic disk from our analysis of space motions. Our sample supports the expectation that WDs with high mass are concentrated near the plane of the Galactic disk
72 DA White Dwarfs Identified in LAMOST Pilot Survey
We present a spectroscopically identified catalogue of 72 DA white dwarfs
from the LAMOST pilot survey. 35 are found to be new identifications after
cross-correlation with the Eisenstein et al. and Villanova catalogues. The
effective temperature and gravity of these white dwarfs are estimated by Balmer
lines fitting. Most of them are hot white dwarfs. The cooling times and masses
of these white dwarfs are estimated by interpolation in theoretical evolution
tracks. The peak of mass distribution is found to be 0.6 which
is consistent with prior work in the literature. The distances of these white
dwarfs are estimated using the method of Synthetic Spectral Distances. All of
these WDs are found to be in the Galactic disk from our analysis of space
motions. Our sample supports the expectation white dwarfs with high mass are
concentrated near the plane of Galactic diskComment: 19 pages, 7 figures, accepted by A
The galactic population of white dwarfs
Original paper can be found at: http://www.iop.org/EJ/conf DOI: 10.1088/1742-6596/172/1/012004 [16th European White Dwarfs Workshop]The contribution of white dwarfs of the different Galactic populations to the stellar content of our Galaxy is only poorly known. Some authors claim a vast population of halo white dwarfs, which would be in accordance with some investigations of the early phases of Galaxy formation claiming a top-heavy initial– mass– function. Here, I present a model of the population of white dwarfs in the Milky Way based on observations of the local white dwarf sample and a standard model of Galactic structure. This model will be used to estimate the space densities of thin disc, thick disc and halo white dwarfs and their contribution to the baryonic mass budget of the Milky Way. One result of this investigation is that white dwarfs of the halo population contribute a large fraction of the Galactic white dwarf number count, but they are not responsible for the lion's share of stellar mass in the Milky Way. Another important result is the substantial contribution of the – often neglected – population of thick disc white dwarfs. Misclassification of thick disc white dwarfs is responsible for overestimates of the halo population in previous investigations.Peer reviewe
A Determination of the Local Density of White Dwarf Stars
The most recent version of the Catalog of Spectroscopically Identified White
Dwarfs lists 2249 white dwarf stars. Among these stars are 118 white dwarfs
that have either reliable trigonometric parallaxes or color-based distance
moduli which place them at a distance within 20 pc of the Sun. Most of these
nearby white dwarfs are isolated stars, but 35 (30 % of the sample) are in
binary systems, including such well known systems as Sirius A/B, and Procyon
A/B. There are also three double degenerate systems in this sample of the local
white dwarf population. The sample of local white dwarfs is largely complete
out to 13 pc and the local density of white dwarf stars is found to be (5.5 +/-
0.8) x 10^-3 pc^-3 with a corresponding mass density of (3.7 +/- 0.5) x10^-3 M
pc^-3.Comment: 20 pages, 3 Postscript figure
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