747 research outputs found
Unusual Carbonaceous Dust Distribution in PN G095.2+00.7
We investigate the polycyclic aromatic hydrocarbon features in the young
Galactic planetary nebula PN G095.2+00.7 based on mid-infrared observations.
The near- to mid-infrared spectra obtained with the AKARI/IRC and the
Spitzer/IRS show the PAH features as well as the broad emission feature at 12
{\mu}m usually seen in proto-planetary nebulae (pPNe). The spatially resolved
spectra obtained with Subaru/COMICS suggest that the broad emission around 12
{\mu}m is distributed in a shell-like structure, but the unidentified infrared
band at 11.3 {\mu}m is selectively enhanced at the southern part of the nebula.
The variation can be explained by a difference in the amount of the UV
radiation to excite PAHs, and does not necessarily require the chemical
processing of dust grains and PAHs. It suggests that the UV self-extinction is
important to understand the mid-infrared spectral features. We propose a
mechanism which accounts for the evolutionary sequence of the mid-infrared dust
features seen in a transition from pPNe to PNe.Comment: 6 pages, 4 figure
On the Nature of AX J2049.6+2939 and AX J2050.0+2914
AX J2049.6+2939 is a compact X-ray source in the vicinity of the southern
blow-up region of the Cygnus Loop supernova remnant (Miyata et al. 1998a). This
source was the brightest X-ray source inside the
Cygnus Loop observed during the ASCA survey project. The X-ray spectrum was
well fitted by a power-law function with a photon index of . Short-term timing analysis was performed and no coherent pulsation
was found. Follow-up observations with ASCA have revealed a large variation in
X-ray intensity by a factor of 50, whereas the spectral shape did not
change within the statistical uncertainties. In the second ASCA observation, we
found another X-ray source, AX J2050.0+2941, at the north east of AX
J2049.6+2939. During the three ASCA observations, the X-ray intensity of AX
J2050.0+2941 varied by a factor of 4. No coherent pulsations could be
found for AX J2050.0+2941.
We have performed optical photometric and spectroscopic observations in the
vicinity of AX J2049.6+2939 at the Kitt Peak National Observatory
(KPNO). As a result, all objects brighter than -band magnitude of 22 in
the error box can be identified with normal stars. Combined with the
X-ray results and the fact that there are no radio counterparts, AX
J2049.6+2939 is not likely to be either an ordinary rotation-powered pulsar
or an AGN. The nature of AX J2049.6+2939 is still unclear and further
observations over a wide energy band are strongly required.
As to AX J2050.0+2941, the long-term X-ray variability and the radio
counterpart suggests that it is an AGN.Comment: 23 pages, 4 figures, Accepted for publication by Astrophysical
Journa
Physical Relation of Source I to IRc2 in the Orion KL Region
We present mid-infrared narrow-band images of the Orion BN/KL region, and
N-band low-resolution spectra of IRc2 and the nearby radio source "I." The
distributions of the silicate absorption strength and the color temperature
have been revealed with a sub-arcsecond resolution. The detailed structure of
the 7.8 micron/12.4 micron color temperature distribution was resolved in the
vicinity of IRc2. A mid-infrared counterpart to source I has been detected as a
large color temperature peak. The color temperature distribution shows an
increasing gradient from IRc2 toward source I, and no dominant temperature peak
is seen at IRc2. The spectral energy distribution of IRc2 could be fitted by a
two-temperature component model, and the "warmer component" of the infrared
emission from IRc2 could be reproduced by scattering of radiation from source
I. IRc2 itself is not self-luminous, but is illuminated and heated by an
embedded luminous young stellar object located at source I.Comment: 20 pages, 11 figures. Minor corrections had been done in the ver.2.
Accepted for publication in PAS
Reflected Light vs. Transmitted Light: Do They Give Different Impressions to Users?
[The 29th International Display Workshops(IDW’22)]Organizing: The Society for Information Display(SID), Date; 14-16 December 2022, Location: Fukuoka International Congress Center[第29回ディスプレイ国際ワークショップ(IDW’22)]主催: 映像情報メディア学会(ITE), 開催日: 2022年12月14日-16日, 会場: 福岡国際会議場The difference in information display between using a projector (reflected light) and a display (transmitted light) is an essential issue. Marshal McLuhan proposed in his book "Laws of Media" the well-known hypothesis that "reflected light makes people analytical and transmitted light makes them emotional." In this study, we matched the display conditions of the projector and display as much as possible. Then we presented the subjects with emotional content (landscape video) and analytical content (threedigit multiplication) and asked them to evaluate their experiences. As a result, we found no statistical difference between the projector and the display evaluations
Interplay between Nitrogen Dopants and Native Point Defects in Graphene
To understand the interaction between nitrogen dopants and native point
defects in graphene, we have studied the energetic stability of N-doped
graphene with vacancies and Stone-Wales (SW) defect by performing the density
functional theory calculations. Our results show that N substitution
energetically prefers to occur at the carbon atoms near the defects, especially
for those sites with larger bond shortening, indicating that the defect-induced
strain plays an important role in the stability of N dopants in defective
graphene. In the presence of monovacancy, the most stable position for N dopant
is the pyridinelike configuration, while for other point defects studied (SW
defect and divacancies) N prefers a site in the pentagonal ring. The effect of
native point defects on N dopants is quite strong: While the N doping is
endothermic in defect-free graphene, it becomes exothermic for defective
graphene. Our results imply that the native point defect and N dopant attract
each other, i.e., cooperative effect, which means that substitutional N dopants
would increase the probability of point defect generation and vice versa. Our
findings are supported by recent experimental studies on the N doping of
graphene. Furthermore we point out possibilities of aggregation of multiple N
dopants near native point defects. Finally we make brief comments on the effect
of Fe adsorption on the stability of N dopant aggregation.Comment: 10 pages, 5 figures. Figure 4(g) and Figure 5 are corrected. One
additional table is added. This is the final version for publicatio
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