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1.
Results from integral spectroscopy of the Herbig-Haro object HH43 are presented. Spectra were obtained with a multi-pupil
spectrograph over the range λλ6400–6800 Å. Based on the ratio of emission lines, as well as on the radial velocities, we have
obtained a more precise picture of the dynamic processes taking place in this object, which belongs to the rare class of “shocked
cloudlet.” In particular, this classification of the object is confirmed by a determination of the exact location of the snock
front. The rate of mass loss from the source star is estimated.
__________
Translated from Astrofizika, Vol. 50, No. 3, pp. 405–414 (August 2007). 相似文献
2.
R. Chan M. F. A. da Silva Jaime F. Villas?da?Rocha 《Astrophysics and Space Science》2012,337(1):185-191
Using the conventional gravastar model, that is, an object constituted by two components where one of them is a massive infinitely
thin shell and the other one is a de Sitter interior spacetime, we physically interpret a solution characterized by a zero
Schwarzschild mass. No stable gravastar is formed and it collapses without forming an event horizon, originating what we call
a massive non-gravitational object. The most surprise here is that the collapse occurs with an exterior de Sitter vacuum spacetime.
This creates an object which does not interact gravitationally with an outside test particle and it may evolve to a point-like
topological defect. 相似文献
3.
The results of morphological and spectral study of the galaxies Kaz 5, Kaz 92, and Kaz 390 are presented. The observations
were made on the 2.6-m telescope at the Byurakan Observatory with the VAGR microlenses spectrograph. Isophotes of the images
of the galaxies are constructed in the Hα, [NII] λλ6584 , 6548, and [SII] λλ6731, 6717 emission lines and in the continuum. The masses of Kaz 5 and Kaz 92 are determined to be 8.6 × 108 M⊙ and 6.1 × 109 M⊙ , respectively. The mass of the gaseous component in the centers of regions I and IV of Kaz 390, which encompass a 1 pixel
area, are also determined. The morphological structure of the central region of Kaz 5 in the observed spectral range, λλ6400–6800?, differs completely from the structure of the same part of the galaxy observed with the 6-m and 2.5-m telescopes. It is shown
that these differences in the structure in images of Kaz 5 are mostly explained by the comparatively low resolution of the
telescope in combination with the VAGR spectrograph. Absorbing matter also contributes to this effect. It is also shown that
a “deficit” of nitrogen has been observed in the region of Kaz 390 studied here (a circle of diameter 40″).
Translated from Astrofizika, Vol. 52, No. 1, pp. 63–74 (February 2009). 相似文献
4.
Corrado Massa 《Astrophysics and Space Science》2006,305(4):377-384
Quantum theory in Robertson – Walker spacetime suggests the existence of a minimal energy ε of the order of 10−45 erg. Reasonable forms for ε give the expansion factor R=R(t)(t= the cosmic time) with no need of gravitational field equations.Einstein's theory should be modified in gravitational fields of strength less than ε c/ħ ∼ 10−8 cm/s2 where c is the speed of light and ħ is the reduced Planck constant. The cosmological term λ is expected to decrease as the universe expands.In the Appendix, ε is derived from a big bang – big crunch Newtonian cosmology. 相似文献
5.
There has been a renewed interest in the recent years in the possibility of deviations from the predictions of Newton’s “inverse-square
law” of universal gravitation. One of the reasons for renewing this interest lies in various theoretical attempts to construct
a unified elementary particle theory, in which there is a natural prediction of new forces over macroscopic distances. Therefore
the existence of such a force would only coexist with gravity, and in principle could only be detected as a deviation from
the inverse square law, or in the “universality of free fall” experiments. New experimental techniques such that of Sagnac
interferometry can help explore the range of the Yukawa correction λ≥1014 m where such forces might be present. It may be, that future space missions might be operating in this range which has been
unexplored for very long time. To study the effect of the Yukawa correction to the gravitational potential and its corresponding
signal delay in the vicinity of the Sun, we use a spherically symmetric modified space time metric where the Yukawa correction
its added to the gravitational potential. Next, the Yukawa correction contribution to the signal delay is evaluated. In the
case where the distance of closest approach is much less than the range λ, it results to a signal time delay that satisfies the relation t(b<λ)≅37.7t(b=λ). 相似文献
6.
Tokio Tsubaki 《Solar physics》1975,43(1):147-175
A technique developed for analysing line profiles with both speed and high accuracy was used to study the physical conditions
of a coronal formation near a quiescent prominence. Detailed analyses of five coronal lines (Fe xiv λ 5303, Fe x λ 6374, Ni xv λ 6702, Fe xv λ 7059, and Fe xi λ 7892) provided total intensities, Doppler width temperatures, ionization temperatures, and velocities.
Dissimilar spatial fluctuations in intensity are obvious for ions grouped according to (low vs high) ionization potentials.
The intensity of the green line shows a local minimum around the observed quiescent prominence; a corresponding but much more
diffuse pattern is visible in the red line intensity.
Large differences are observed in temperatures derived by different means. In particular,
, while
, and
. The differences between
and
are taken as direct evidence of temperature inhomogeneity. One can thus put little significance in T
e
(xi/x). T
D(λ5303) and T
e
(xv/xiv) fluctuate nearly in parallel at each slit height, with a weak local minimum evident around the prominence. The discrepancy
between these two can be removed if a non-thermal turbulent motion of 6–16 km s−1 is assumed. Variations with height of both T
D(λ5303) and T
e
(xv/xiv) suggest that the coronal temperature maximum is located no more than 15000 km above the top of spicules. A negative gradient
of about 6 deg km−1 is found in the height variation of T
D(λ5303).
The height variation of the green line wavelength shows that the majority of coronal material in this region is flowing from
west to east on the Sun, with the highest velocity of 12 km s−1 found at the lowest heights. This motion is in the same sense as that of the nearby coronal rain, as determined both from
the spectra and wavelength-shifted Hα filtergrams. Superposed on the above flow is a systematic velocity field of up to ±5
km s−1. This field similarly reaches maximum amplitudes at lowest heights showing a local maximum around the prominence.
On leave from Institute of Earth Science and Astrophysics, Shiga University, Ohtsu 520, Japan, as 1973–75 National Academy
of Science/National Research Council Senior Post-Doctoral Research Associate at Sacramento Peak Observatory. 相似文献
7.
Kejun Li Youji Ding Jinming Bai Shuhua Zhong Jiayu Xuan Qiongying Li 《Solar physics》1994,150(1-2):87-97
The quickest descent method and the multi-layer model are proposed to analyse symmetrical and asymmetrical line profiles of
loops in this paper. By fitting observed lines, the physical parameters such as Doppler width, Δλ
D
, the optical thickness at line centre,τ
λ0, and the line displacement, Δλ
0, can be directly obtained, Using this method, some symmetrical and asymmetrical line profiles of both the loop prominence
on February 18, 1984 and the loop on August 17, 1989 are fitted. It is found that the method mentioned in this paper is characterized
by rapid convergence, high precision, and less scatter. 相似文献
8.
Based on our spectroscopic observations of the variable planetary nebula IC 4997 in 2003–2009, we have obtained the relative
fluxes in optical emission lines. The interstellar extinction c = 0.35 has been found from the Balmer decrement by taking into account the effect of self-absorption in hydrogen lines in
dense nebular regions. The variations in the Balmer decrement point to variability of the self-absorption and circumstellar
extinction. We have investigated the variations in the relative intensities of some spectral lines and their ratios with time.
The drop in the ratios F(λ4363)/F(Hγ) and F(λ363)/F(λ4959) that began back in 1990–1995 has continued, suggesting a decrease in the electron density and temperature in the central
nebular region. The ratio F(λ6731)/F(λ6717) has remained constant. It gives an estimate for the electron density in the outer regions of IC 4997, N
e
∼ 104 cm−3. 相似文献
9.
In this paper we have studied in detail (numerically) the trajectories of charged particles in a magnetic field (dipolar at
infinity) associated with a static star in the framework of Rosen's bimetric theory of gravity. It was found that there do
exist potential wells that allow possible trapping of particles in stable orbits both on and off the equatorial plane. A particularly
interesting feature that has shown up is the fact that the characteristics of the effective potential wellV
eff depend on the ratio of the magnetic field strength parameter λ, and the angular momentumL of the charged particle. For values lower than a critical (λ/L)
c
the potential well lies within the regionr≤2m. 相似文献
10.
An alternative approach is proposed for the study of the non-cosmological redshifts. The approach is based on the radiation formulation of the tidal gravitation acceleration in geometrodynamics and the spacetime curvature around the massive objects. The resulting formalism can be used to study the object mass and the gravitation magnitude from the observed spectral lines with redshifts. 相似文献
11.
Larisa A. Yakovina Yakiv V. Pavlenko Carlos Abia 《Astrophysics and Space Science》2003,288(3):279-286
Lithium abundances in the atmospheres of the super Li-rich C-giants WZ Cas and WX Cyg are derived by the spectral synthesis
technique using the Li I resonance line at λ670.8 nm and three subordinate lines at λλ 812.6, 610.4 and 497.2 nm. The differences
between the Li abundances derived from the λ670.8 nm line and the λλ 497.2, 812.6 nm lines do not exceed ±0.5 dex. The lithium
line at λ610.4 nm provides typically lower abundances than the resonance line (by ≈ 1 dex). The mean LTE and NLTE Li abundances
from three Li I lines (excluding λ610.4 nm) are 4.7, 4.9 for WZ Cas, and 4.6, 4.8 for WX Cyg, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
Jesús Gallego 《Astrophysics and Space Science》1998,263(1-4):1-14
The evolution of the Star Formation Rate (SFR) density of the Universe as a function of look-back time is a fundamental parameter
in order to understand the formation and evolution of galaxies. The current picture, only outlined in the last years, is that
the global SFR density has dropped by about an order of magnitude from a redshift of z∼1.5 to the current value at z=0. Because
these SFR density studies are now extended to the whole range in redshift, it becomes mandatory to combine data from different
SFR tracers. At low redshifts, optical emission lines are the most widely used. Using Hα as current-SFR tracer, the Universidad
Complutense de Madrid (UCM) Survey provided the first estimation of the global SFR density in the Local Universe. The Hα flux
in emission is directly related to the number of ionizing photons and, modulo IMF, to the total mass of stars formed. Metallic
lines like [OII]λ3727 and [OIII]λ5007 are affected by metallicity and excitation. Beyond redshifts z∼0.4, Hα is not observable
in the optical and [OII]λ3727 or UV luminosities have to be used. The UCM galaxy sample has been used to obtain a calibration
between [OII]λ3727 luminosity and SFR specially suitable for the different types of star-forming galaxies found by deep spectroscopic
surveys in redshifts up to z∼1.5. These calibrations, when applied to recent deep redshift surveys confirm the drop of the
SFR density of the Universe since z∼1 previously infered in the UV. However, the fundamental parameter that determines galactic
evolution is mass, not luminosity. The mass function for local star-forming galaxies is critical for any future comparison
with other galaxy populations of different evolutionary status. Hα velocity-widths for UCM galaxies indicate that besides
a small fraction of 1010-1011 M⊙ starburst nuclei spirals, the majority have dynamical masses in the ∼109 M⊙ range. A comparison with published data for faint blue galaxies suggests that star-forming galaxies at z∼1 would have SFR
per unit mass and burst strengths similar to those at z=0, but being intrinsically more massive.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
We present two new luminous blue variable (LBV) candidate stars discovered in the M33 galaxy. We identified these stars as
massive star candidates at the final stages of evolution, presumably with a notable interstellar extinction. The candidates
were selected from the Massey et al. catalog based on the following criteria: emission in H
α
, V<18./m 5 and 0.m 35 < (B - V) < 1.m 2. The spectra of both stars reveal a broad and strong H
α
emission with extended wings (770 and 1000 kms−1). Based on the spectra we estimated the main parameters of the stars. Object N45901 has a bolometric luminosity log(L/L⊙) = 6.0–6.2 with the value of interstellar extinction A
V
= 2.3 ± 0.1. The temperature of the star’s photosphere is estimated as T⋆ ∼ 13000–15000 K, its probable mass on the Zero
Age Main Sequence is M∼ 60–80 M⊙. The infrared excess in N 45901 corresponds to the emission of warm dust with the temperature Twarm ∼ 1000 K, and amounts
to 0.1%of the bolometric luminosity. A comparison of stellar magnitude estimates from different catalogs points to the probable
variability of the object N45901. Bolometric luminosity of the second object, N125093, is log(L/L⊙) = 6.3 − 6.6, the value of interstellar extinction is A
V
= 2.75 ± 0.15. We estimate its photosphere’s temperature as T⋆∼ 13000–16000K, the initial mass as M ∼ 90–120 M⊙. The infrared excess in N125093 amounts to 5–6% of the bolometric luminosity. Its spectral energy distribution reveals two
thermal components with the temperatures Twarm ∼ 1000K and Tcold ∼ 480 K. The [Ca II] λλ7291, 7323 lines, observed in LBV-like stars Var A and N93351 in M33 are also present in the spectrum of N 125093. These lines
indicate relatively recent gas eruptions and dust activity linked with them. High bolometric luminosity of these stars and
broad H
α emissions allow classifying the studied objects as LBV candidates. 相似文献
14.
E. L. Karapetyan 《Astrophysics》2006,49(3):299-305
Spectral observations of 19 galaxies with UV-excesses from Kazarian’s list are reported. The spectra were obtained with the
2.6-m telescope at the Byurakan Observatory using the SCORPIO spectral camera. A grism was used to obtain spectra in the wavelength
interval λλ7420-3920 Å. 43 spectra in which emission lines are mainly observed were obtained from the 19 galaxies, except
for the spectra of Kaz 21, Kaz 178, Kaz 183, and Kaz 184. The spectra of Kaz 17, Kaz 151, Kaz 153, and Kaz 357 have type Sy2
galactic features. In the spectra of the galaxies Kaz 17, Kaz 151, and Kaz 153, absorption lines are observed along with high
excitation emission lines such as HeI λ5876 Å and HeII λ4686 Å. No lines were observed within the interval λλ7420-3920 Å in
the spectra of the galaxies Kaz 183 and Kaz 184.
__________
Translated from Astrofizika, Vol. 49, No. 3, pp. 351–358 (August 2006). 相似文献
15.
Results from a spectrophotometric study of the galaxy Kaz 701 are presented. Spectra of this galaxy were obtained on the 2.6-m
telescope at the Byurakan Observatory with the SCORPIO spectral camera. In the spectra of Kaz 701, strong Hα, [OIII] λλ5007,
4959, and Hβ emission were observed, and the [SII]λλ6731, 6717 lines were observed with moderate intensities, while the [NII]λ6584
line was scarcely noticeable in the spectra obtained in 2004, but was much more intense in the spectra of 2009. The lines
observed in the spectrum of this galaxy are typical of type Sy2 galaxies. A component was observed in the red wings of both
the Hα and Hβ lines in the data of 2004, but, although these lines were stronger, these components were absent in the spectra
taken in 2009. The relative intensities, equivalent widths, and half widths of these lines are given. These data, obtained
in different observation periods (2004 and 2009), differ greatly; that is, the emission is variable. 相似文献
16.
E. Xanthopoulos 《Astrophysics and Space Science》2000,274(3):523-537
We present narrow-band emission line (Hα + [N II]λλ 6548, 6583, [O III] λλ 4959, 5007)as well as green or red continuum images
of selected Seyfert galaxies. The sample includes NGC 7214, IC 4218, Akn 479, Mrk 915, IC 1515 and F 348.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
The infrared star cluster RCW 38 IR Cluster, which is also a massive star-forming region, is investigated. The results of
observations with the SEST (Cerro La Silla, Chile) telescope on the 2.6-mm 12CO spectral line and with SIMBA on the 1.2-mm continuum are given. The 12CO observations revealed the existence of several molecular clouds, two of which (clouds 1 and 2) are connected with the object
RCW 38 IR Cluster. Cloud 1 is a massive cloud, which has a depression in which the investigated object is embedded. It is
not excluded that the depression was formed by the wind and/or emission from the young bright stars belonging to the star
cluster. Rotation of cloud 2, around the axis having SE-NW direction, with an angular velocity ω = 4.6 · 10−14 s−1 is also found. A red-shifted outflow with velocity ∼+5.6 km/s, in the SE direction and perpendicular to the elongation of
cloud 2 has also been found. The investigated cluster is associated with an IR point source IRAS 08573-4718, which has IR
colors typical for a non-evolved embedded (in the cloud) stellar object. The cluster is also connected with a water maser.
The SIMBA image shows the existence of a central bright condensation, coinciding with the cluster itself, and two extensions.
One of these extensions (the one with SW-NE direction) coincides, both in place and shape, with cloud 2, so that the possibility
that this extension might also be rotating like cloud 2 is not excluded. In the vicinity of these extensions there are condensations
resembling HH objects.
Published in Astrofizika, Vol. 51, No. 1, pp. 29–40 (February 2008). 相似文献
18.
O. G. Badalyan 《Astronomy Letters》2012,38(1):51-61
The 1943–2001 data on the brightness of the coronal green λ530.3 nm line are used to investigate the surface distribution of the north-south (N-S) asymmetry index A. Synoptic maps of the asymmetry index in 784 successive Carrington rotations have been constructed. The results are presented
in the form of a movie that visualizes the time variation in the spatial distribution of the asymmetry. Examination of a series
of synoptic maps shows that the time variation in the general distribution of the A index over the solar surface has a number of peculiar features. In particular, the latitude-longitude regions with the dominance
of the green line brightness in one of the hemispheres are replaced by similar (in shape) regions with its dominance in the
other hemisphere after 14–18 rotations-in other words, the map, as it were, turns into its negative. This may be a manifestation
of the quasi-biennial oscillations in the N-S asymmetry. The synodic rotation period of the asymmetry “structures” has been
determined. It has turned out to be equal to the period of the fast coronal rotation mode found previously from the large-scale
brightness distribution of the coronal green line, i.e., this is 27 days on the equator and slightly more than 28 days at
high latitudes. The N-S asymmetry and its characteristics should be taken into account when considering the dynamo mechanism. 相似文献
19.
Fluctuational mechanism for the formation of proton vortices in the superfluid core of neutron stars
The Gibbs thermodynamic potential of a proton vortex interacting with the normal core of a neutron vortex of radius r << λ (λ is the penetration depth) that is parallel to it and has an outer boundary of radius b is calculated. It is shown that, under
this assumption, the capture of only one vortex by the core is energetically favorable. The force acting on the proton vortex
owing to the entrained current is found and it is always directed toward the core. The corresponding force for a proton antivortex
is directed toward the outer boundary of the neutron vortex. The Ginzburg-Landau equation is solved for a vortex-antivortex
system and its Gibbs function is calculated. It is shown that at large distances from the core, vortex-antivortex pairs can
form because of fluctuations. Acted on by the entrainment current, the antivortex moves outward, while the vortex stays inside
the neutron vortex. It is shown that the best conditions for fluctuational pair production, followed by separation, exist
near the outer boundary. It is shown that new proton vortices can develop only in a region where the entrainment magnetic
field strength H (ρ) > HC1 (HC1 is the lower critical field).
__________
Translated from Astrofizika, Vol. 51, No. 1, pp. 139–149 (February 2008). 相似文献
20.
Using the third-order WKB approximation, we evaluate the quasinormal frequencies of massless Dirac field perturbation around
a deformed black hole in the Hořava-Lifshitz gravity with coupling constant λ=1. Our result shows that the Hořava-Lifshitz parameter α plays an important role for the quasinormal frequencies and we discuss the variation of quasinormal frequencies with α. Moreover, we find that the massless Dirac field perturbations decay more slowly in the deformed Hořava-Lifshitz gravity. 相似文献