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1.
Preliminary results of observations of a region containing known H stars are presented. The observations were made on the 2.6-m telescope of the V. A. Ambartsumian Byurakan Astrophysical Observatory in August 2000. A VAGR integral field spectrograph was used in the observations. The size of the region studied is about 6×11 arcmin. Besides the two already known, five new H stars and five HHL objects were discovered in this region. One of these stars coincides with the well-known object RNO 127. One infrared and one cometary nebula were discovered. The presence of so many peculiar objects in a region of such size suggests that it is one of the youngest star-forming regions. 相似文献
2.
Preliminary results from a search for emission stars in the neighborhood of Cyg OB7 are reported. A new region of size 14×14
arc min lies 12 arc min to the south of HH 448. 17 new objects have been found, of which one is related to a nebula with an
interesting shape and, apparently, the characteristics of a cometary nebula. Inside the nebula there are 4 faint, compact
formations with very high proper motions. The spectrum of a star shows that it is of spectral class K9-M0 and is a T Tau type
star at a distance of 220 pc. Most of the discovered stars with a strong or intermediate Ha emission line intensity are presumably
also T Tau stars. This region appears to be a continuation of the T association around HH 448. 相似文献
3.
Spectroscopic and photometric observations of objects embedded in the L1340 dark cloud are reported. An entire series of HH-objects in the RN07 region was discovered, including new ones that form two or three flows. It is suspected that several cases of HH emission are included. In addition, 14 emission stars, of which 11 are new, were found in this region. Most of these stars are localized inside the RN07 nebula which, therefore, encompasses a compact cluster of very young stars. Other nebulous objects inside the L1340 cloud, many of which are associated with IR sources, are described. As a whole, this cloud represents an extremely active star forming region. 相似文献
4.
Results of spectral observations of blue stellar objects from the FBS are presented for the purpose of classifying them, discovering
new interesting objects, and studying the FBS sample as a whole. 99 FBS objects in the band with central declination δ = +43°
were observed on the 2.6-m telescope at the Byurakan Observatory in 1987–1991 and have been digitized using a professional
scanner and processed by MIDAS in a way similar to CCD spectra. 12 objects were also observed with the BAO-2.6 and OHP-1.93
telescopes using modern techniques during 1997–2000; some were repeated observations for confirming or correcting the classifications.
A new planetary nebula, 7 white dwarfs, 78 hot subdwarfs, 9 HBB stars, and 6 stars in classes F-G were discovered. Proper
motions in the range 57–84 mas/year were obtained for three stars (DA, DAB, and sdB). Three stars (a white dwarf and two subdwarfs)
are identified with x-ray sources. The spectra of the 30 most interesting objects are given.
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Translated from Astrofizika, Vol. 49, No. 3, pp. 391–405 (August 2006). 相似文献
5.
Five new Herbig-Haro objects (HH 1036–1040) have been discovered in the neighborhood of the nebula GM 2–41 in a region with
an area of 14′ × 14′, at the center of the HII region DR 15 located in the southern periphery of the Cyg OB2 association.
Four of them have a complex structure typical of HH flows. Hydrogen molecular emission is detected in the object HH 1036 using
archived images from the Spitzer telescope. Two new infrared nebulae illuminated by very red young stellar objects are also
found. 相似文献
6.
High dispersion CCD spectra are used to study the profiles of the Hα and Hβ lines of 48 stars in early spectral classes in
the young diffuse binary cluster h/χ Per. In addition, moderate resolution spectra of 15 B and Be stars were taken over the
interval 4400–4960 Å. One or, possibly, two new Be stars are discovered. The major parameters of the Hα line are measured
for the observed B and Be stars. The spectra over 4400–4960 Å are used to estimate Teff, logg, and υsin i. No traces of emission are detected in the Hα line profiles for 28 of the stars and emission is observed in the Hα line
for 20. During our observations an absorption profile of the Hα line was observed for some of the stars, such as Oo146, Oo566,
Oo922, and Oo1268, although they have previously been identified as Be stars. A significant long-term variability of the Hα
line is discovered for the Be stars Oo1161 and Oo2242. Oo2371 manifests a variability in its faint emission spectrum which
is typical of close binary systems that include a Be star.
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Translated from Astrofizika, Vol. 51, No. 2, pp. 305–319 (May 2008). 相似文献
7.
Fabry-Perot Interferometric observations were made on Orion Nebula in the forbidden emission line [S II] 6731 Å line. The observed field is about 6 × 6 on the face of the nebula and it covers the Orion Trapezium stars and the nearby regions. The relative line of sight velocities which denote the average deviations from the systematic velocities were derived at a large number of points in the nebula. Velocities were found to show a gradient towards the north of Trapezium stars. Large blue shifted velocities were found at the nebular boundaries, probably associated with the ionization fronts. The observed velocities, in general, show agreement with the flow model of Balick, Gull and Smith (1980). 相似文献
8.
J. Reyes-Iturbide P. F. Velázquez M. Rosado A. Rodríguez-González R. F. González A. Esquivel 《Monthly notices of the Royal Astronomical Society》2009,394(2):1009-1015
We present 3D hydrodynamical simulations of the superbubble M17, also known as the Omega Nebula, carried out with the adaptive grid code yguazú-a , which includes radiative cooling. The superbubble is modelled considering the winds of 11 individual stars from the open cluster inside the nebula (NGC 6618), for which there are estimates of the mass-loss rates and terminal velocities based on their spectral types. These stars are located inside a dense interstellar medium, and they are bounded by two dense molecular clouds. We carried out three numerical models of this scenario, considering different line-of-sight positions of the stars (the position in the plane of the sky is known, thus fixed). Synthetic thermal X-ray emission maps are calculated from the numerical models and compared with ROSAT observations of this astrophysical object. Our models successfully reproduce both the observed X-ray morphology and the total X-ray luminosity, without taking into account the thermal conduction effects. 相似文献
9.
We report observations of 24 stars in the fields of the three Seyfert galaxies MCG +08-23-067, Mrk 817, and Mrk 290. The observations
were made with a CCD array photometer in the BVRcIc bands. The V magnitudes of the observed stars ranged from 13.5 and 17.2.
For stars of approximate magnitude 15, the typical photometric errors are 0.010, 0.011, 0.008 and 0.011 magnitude in the BVRI
bands, respectively. The BVRI magnitudes of all these stars were not known previously. In the field of the galaxy Mrk 290
a star has been found that probably has a periodic brightness variation with P=1.518 days and the mean value V=14.80 and which
may belong to the class of “spotted” stars. 14′x14′ charts are supplied for identifying the stars. These results can be used
for differential photometry of active galactic nuclei in the BVRI bands.
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Translated from Astrofizika, Vol. 51, No. 1, pp. 41–50 (February 2008). 相似文献
10.
We present new radio observations of molecular lines in the region of high mass star formation, namely G122.0-7.1. A large-scale
map of the emission observed in the 12CO (J = 1−0) and 13CO (J = 1−0) lines covers the area of 15′ × 9′, revealing two dense regions. The molecular bipolar outflows have been resolved
in ASO1 region. It is associated with the known candidate YSO nearby IRAS 0042 + 5530. Also, a new dense region has been discovered
in the North-Western part of the G122.0-7.1 at a distance of 5′ from IRAS 0042 + 5530. Its position is close to the peak of
4850 MHz emission.
The text was submitted by the authors in English. 相似文献
11.
The populations of B and Be-stars in the young open clusters NGC 7419 and NGC 659 are studied. Lowresolution spectral observations
in the region of the Hα line are used to study 34 members of NGC 7419 and additional spectra in the range λ3700-6200 ? are
obtained for 12 stars. During the period of our observations, four previously identified Be-stars manifested an absorption
profile for the Hα line. Emission in the Hα line is observed in the spectra of 21 objects. The members of the cluster NGC
7419 are classified as to spectral type. The position of the Be-stars on a two-color IR diagram and a comparison with the
position of the objects in other clusters with similar ages cast doubt on the existence of two starformation waves. Moderate
resolution spectra were obtained for 22 stars in the cluster NGC 659 over wavelengths of λ4050-5200 ? and for 7 objects in
the neighborhood of the Hα line. Emission is observed in both the Hα and Hβ lines for two of the five Be-stars that were studied,
while faint emission appears only in the Hα line in one of the stars. The other members of the cluster show no signs of emission
in these spectra. Teff, log g, and Vsini are estimated for the observed stars. It is found that 5 of the objects are not members of the cluster. 相似文献
12.
43 stellar objects with Hα emission are discovered by slitless spectroscopy in a 14’ × 14' area near the nebula GM 2-41 located
in the HII region DR 15 at the southern edge of the Cyg OB2 association. Emission is detected for the first time for 30 of
these objects. Based on VI and JHK photometric data, the overwhelming majority of these objects are classified as young stellar
objects in spectral classes F7-M3 with ages of ~1 Myr. The stars are distributed nonuniformly and form two groups which have
the same coordinates as the UCHII regions G0.79 + 0.3 and G79.2 + 0.4. 相似文献
13.
Symbiotic stars that are strong radio sources and have cool dust emitting in the infrared are expected to have extended emission
nebulae around them. In order to search for such emission nebulae, we have carried out CCD imaging of three symbiotic stars
(R Aqr, RR Tel and H1-36) with narrow-band filters centred at the emission lines of [O III] λ5007, Hα λ6563, [N II] λ6584,
[S II] λ6717 + 6731. RR Tel and H1-36 images do not show any extended nebulosities around them. The CCD image of the R Aqr
nebulosity in the high excitation [O m] line is different from its image in Hα and the low excitation lines of [N II] and
[S II] indicating ionization-stratification in the nebula. In H1-36 the optical nebulosity (if it exists) is smaller than
∽2 arcsec while the radio image size is known to be large (∽5 arcsec). This behaviour is opposite to that seen in R Aqr in
which the radio emission comes from the core region of a much larger optical nebulosity. Interstellar and/or circumstellar
extinctions are suggested to be responsible for this difference 相似文献
14.
M. C. Weisskopf M. Karovska G. G. Pavlov V. E. Zavlin T. Clarke 《Astrophysics and Space Science》2007,308(1-4):151-160
We present an overview of Chandra X-ray Observatory observations of neutron stars. The outstanding spatial and spectral resolution of this great observatory
have allowed for observations of unprecedented clarity and accuracy. Many of these observations have provided new insights
into neutron star physics. We present an admittedly biased and overly brief review of these observations, highlighting some
new discoveries made possible by the Observatory’s unique capabilities. This includes our analysis of recent multiwavelength
observations of the putative pulsar and its pulsar-wind nebula in the IC443 SNR.
相似文献
15.
A. Nota A. Pasquali L. Drissen C. Leitherer C. Robert W. Schmutz 《Astrophysics and Space Science》1995,224(1-2):261-265
New high resolution echelle observations of Ofpe/WN9 stars in the Large Magellanic Cloud have been obtained in the wavelength region 4000 - 8000 Å. We find that five Ofpe/WN9 stars display in their spectra nebular emission lines [NII], [SII] and also [OIII], previously unreported for BE381 and S119. At least in these two cases we can conclude that the stars are surrounded by an associated nebula, thus strengthening the relationship between Ofpe/WN9 stars and LBVs. 相似文献
16.
H.M. Tovmassian A. Gonzalez L.J. Corral G.H. Tovmassian 《Astrophysics and Space Science》1997,257(1):63-82
The consideration of the additional data on the distribution of OB stars, of the dust matter (the IRAS data at 100 m, and of the results of observations 120–300 m), of the X-ray emission, of the continuum radio emission, and of the data on the proper motions of stars in the Carina nebula, proved the made suggestion (Tovmassian et al., 1993, 1994), that the observed specific distribution of the mentioned objects in the Carina nebula could be due to some explosion which took place in its central region. 相似文献
17.
Observations obtained with the Midcourse Space Experiment (MSX) satellite reveal for the first time the complex mid-infrared morphology of the entire Carina Nebula (NGC 3372). On the largest size scale of approximately 100 pc, the thermal infrared emission from the giant H ii region delineates one coherent structure: a (somewhat distorted) bipolar nebula with the major axis perpendicular to the Galactic plane. The Carina Nebula is usually described as an evolved H ii region that is no longer actively forming stars, clearing away the last vestiges of its natal molecular cloud. However, the MSX observations presented here reveal numerous embedded infrared sources that are good candidates for sites of current star formation. Several compact infrared sources are located at the heads of dust pillars or in dark globules behind ionization fronts. Because their morphology suggests a strong interaction with the peculiar collection of massive stars in the nebula, we speculate that these new infrared sources may be sites of triggered star formation in NGC 3372. 相似文献
18.
G. A. Gurzadyan 《Astrophysics and Space Science》1992,193(1):105-107
The emission lines in the spectra of some planetary nebula experience variations with the time. These variations (due to evolution effects and by their nature) differ from the spectral changes which we usually observe in stars. It appears that the long-scale and systematic observations on the intensity behaviour of different emission lines of nebula may be used as an independent indicator to receive a principally new and quite unpredicted category of information related to the physics of nebulae and their nuclei. Particularly, the analysis of long standing observations carried out in relation to the forbidden lines 4363 [Oiii] andN
1+N
2 [Oiii] of double-ionized oxygen lead to a conception about the possible existence ofrelativistic electrons of moderate energy in planetary nebulae and the generation oftransition radiation as a result of electrodynamic interaction of these electrons with the dust particles in nebula (Gurzadyan, 1991). Just on the basis of the same observational material, the long-scale periodicity in the activity or variations of a star-like planetary nebula IC 4997 is discovered about which is the present note. 相似文献
19.
A. Roman-Lopes Z. Abraham R. Ortiz A. Rodriguez-Ardila 《Monthly notices of the Royal Astronomical Society》2009,394(1):467-478
K -band spectra of young stellar candidates in four Southern hemisphere clusters have been obtained with the Gemini Near-Infrared Spectrograph in Gemini South. The clusters are associated with IRAS sources that have colours characteristic of ultracompact H ii regions. Spectral types were obtained by comparison of the observed spectra with those of a near-infrared (NIR) library; the results include the spectral classification of nine massive stars and seven objects confirmed as background late-type stars. Two of the studied sources have K -band spectra compatible with those characteristic of very hot stars, as inferred from the presence of C iv , N iii and N v emission lines at 2.078, 2.116 and 2.100 μm, respectively. One of them, I16177_IRS1, has a K -band spectrum similar to that of Cyg OB2 7, an O3If* supergiant star. The nebular K -band spectrum of the associated Ultra-Compact (UC) H ii region shows the s-process [Kr iii ] and [Se iv ] high excitation emission lines, previously identified only in planetary nebula. One young stellar object was found in each cluster, associated with either the main IRAS source or a nearby resolved Midecourse Space eXperiment ( MSX ) component, confirming the results obtained from previous NIR photometric surveys. The distances to the stars were derived from their spectral types and previously determined JHK magnitudes; they agree well with the values obtained from the kinematic method, except in the case of IRAS 15408−5356 , for which the spectroscopic distance is about a factor of 2 smaller than the kinematic value. 相似文献
20.
Recent studies of the star formation region BBW 36 and associated molecular clouds are presented. The 12CO (1-0) observations, carried out with the 15-m SEST (Swedish-ESO) telescope (Cerro La Silla, Chile), revealed the existence
of cloud a, connected with BBW 36 and of cloud b, having elongation in SE-NW direction. A red-shifted molecular outflow with
velocity ∼+5 km/s (with respect to cloud a), having a direction parallel to the line of sight, was also observed. VLA observations
showed the presence of a source VLA 2 at 3.6 cm with an elongation in the N-S direction. It is suggested that the VLA 2 source
coincides with a dust disc (surrounding the object BBW 36). The star 3, which is one of the YSOs in the star-forming region
BBW 36 and is connected with a bright comma-like nebula, can be the source of the molecular outflow. The star 3 has very high
IR colors and is associated with an IRAS point source IRAS 07280-1829, which has IR colors, typical for an IRAS point source,
connected with a water maser. On the 2MASS K image of BBW 36 we can see the existence of a bright nebula; a group of stars
is embedded in that nebula, and among these stars there are stars with dust discs (or envelopes). On the 2MASS K image several
spiral jets are also present, some of them with a condensation at the end.
Published in Astrofizika, Vol. 51, No. 3, pp. 469–477 (August 2008). 相似文献