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On the Distance and Structure of W80
The continuum radiation of the Galactic region located atl=85deg, b=-0.5deg is well defined by its 11 cmemission. The region, extended 3° in diameter, is cataloged as W80,and its optical images show the North America and Pelican Nebulaecomplexes. In this paper we present new distance measurements andphysical parameters obtained from radio recombination line observationsat a frequency near 1.4 GHz. Four structures are identified in theregion under study: a near structure is located at a distance of about0.7 kpc, another structure lies on the east side of W80 at a distance of1.7 kpc, there is a concentration of ionized gas on the west side at adistance of 2.7 kpc, and a fourth structure is found further away at 3.3kpc, which does not seem to belong to the W80 complex. The results arepresented using the (X, Y, Z)-coordinates of the Galactic plane. Themodel used assumes a constant electron temperature Te=6800 Kand also assumes homogeneity. Our results seem to indicate that theionized hydrogen of W80 spreads along the line of sight instead ofclumping at one distance. We obtain values of the electron density andthe ionization parameter between ne=5 and 16 cm-3and U=51 and 110 cm-2 pc, respectively.
| A new view of the Cygnus X region. KOSMA 13CO 2 to 1, 3 to 2, and 12CO 3 to 2 imaging
Context: .The Cygnus X region is one of the richest star formation sitesin the Galaxy. There is a long-standing discussion about whether theregion is a chance superposition of several complexes along the line ofsight or a single coherent complex at a distance of 1.5 to 2 kpc. Aims: . Combining a 13CO 2 to 1 survey taken with the KOSMA 3m telescope with mid-IR images from MSX provides a way to improve ourunderstanding of the spatial structure of the complex. The physicalproperties of the molecular gas can be derived in more detail as it wasdone in former studies. Methods: . Cygnus X has been mapped in13CO J =2to1 (10.8 deg^2) at an angular resolution of 130'',as well as for smaller areas in 12CO and 13CO J =3 to 2 (90''), using the KOSMA 3 m submm-telescope. Results: .Weidentified 91 clumps in 13CO 2 to 1 that have a typicalexcitation temperature of 10-30 K, an average density of1.3×103 cm-3, radii of 1-8 pc, and masses ofa few hundred to several ten thousand M_ȯ. The main cloudcomplexes, the northern part (M≃2.8×10^5 M_ȯ) includingDR21 and W75N and the southern region (M≃4.5×10^5 M_ȯ)with IC 1318 b/c and AFGL2591, show differences in their physicalproperties. The 13CO emission is closely associated withmid-IR emission seen with MSX. We find evidence that Cygnus OB2 andCygnus OB9 are affecting the molecular material in Cygnus X. Conclusions: . Since essentially all molecular cloud complexes in CygnusX form groups that are connected by molecular emission (visible inchannel and position-velocity maps) and partly show evidence ofinteraction with UV radiation, we conclude that most of the objects seenin this region are located at the same distance, i.e., that of the OB2cluster at 1.7 kpc, which is also consistent with the distances ofother OB associations (OB9, OB1) in Cygnus X.
| CCD Photometry and Classification of Stars in the North America and Pelican Nebulae Region. III. The Dark Cloud L935
Magnitudes and color indices of 430 stars down to V ˜ 17.5 mag inthe eight-color Vilnius + I photometric system were obtained in fourareas of diameter 20' within the dark cloud L935 separating the NorthAmerica and Pelican nebulae. Spectral types, interstellar colorexcesses, extinctions and distances of stars were determined from thephotometric data. The plot of extinction vs. distance shows that thedark cloud begins at a distance of 520±50 pc. About 40 stars inthe cloud, mostly K and M dwarfs, are suspected to have Hαemission; these stars also exhibit infrared excesses. Four of them areknown pre-main-sequence stars. Our star set contains J205551.3+435225 (V= 13.24) which, according to Camerón and Pasquali (2005), is theO5 V type star ionizing the North America and Pelican nebulae. If thisspectral type is confirmed, the star would have an extinctionAV between 9 and 10 magnitudes (depending on the acceptedextinction law) and a distance which is not very different from the dustcloud distance.
| Is G84.0+0.8 a high mass star formation site near the edge of the Pelican nebula?
We present visible and near-infrared observations of the G84.0+0.8 HIIregion, a bright compact knot projected within the boundaries of the W80complex dominated by the North America and Pelican nebulae. The spectrumof the nebula indicates a temperature of the ionizing stellar spectrumT* ≃ 40 000{-}45 000 K (corresponding to a O7-O5 star)and a density of the HII region n ≃ 460 cm-3, with aforeground extinction of AV ≃ 5.9 mag. A comparison ofnarrow-band near-infrared images through the Brγ and the H2 S(1)v=1 → 0 filters shows that G84.0+0.8 consists of a fan-shapedcavity in a molecular cloud at least partly bounded by aphotodissociation region, filled with Brγ-emitting ionized gas,and with a compact cluster at the tip of the fan. The brightest star atthe position of the cluster is found to be a late G-type interloper.While membership of G84.0+0.8 in the local arm is well established fromexisting radial velocity measurements of the ionized gas, we find thatthe ionizing flux estimated from the size and density of the nebula onthe one hand, and the radio continuum properties of the nebula on theother hand, are well below the expected ionizing flux of a mid, or evenlate, O-type star. We consider the possibility that G84.0+0.8 might beexternally ionized by a nearby mid-O star. Currently availableobservations do not definitely confirm or reject the membership ofG84.0+0.8 in the W80 complex, although a larger distance seems favoredby the available data. Nevertheless, we can firmly rule out thepossibility that it represents a massive star forming site in thatcomplex, as its appearance as a compact HII region containing anembedded cluster may lead one to think.
| A Parsec-Scale Outflow in the Rosette Molecular Cloud?
We report on new observations of a purported parsec-scale outflow in thehostile environment at the boundary of the Rosette Nebula, a well-knownH II region driven by several O stars in the open cluster NGC 2244, andthe Rosette Molecular Cloud (RMC). Several emission features were firstreported by Ybarra & Phelps in 2004 , but with only optical [S II]imaging, their nature could not then be established. Our newnear-infrared (NIR) H2 imaging observations reveal bulletedNIR emission between a Two Micron All Sky Survey (2MASS) NIR excesspoint source and the optical [S II] emission for RMC C of Ybarra &Phelps. Analysis of the 2MASS colors indicates that the point source islikely to be a Class I young stellar object (YSO). Together theseresults imply that RMC C is in fact part of a true YSO outflow, nowdesignated HH 871. The presence of additional [S II] emission,apparently connected to the HH 871 outflow but separated by ~1.2 pc,assuming a distance of 1600 pc for the RMC, also lends support to theYbarra & Phelps hypothesis that a parsec-scale outflow is present inthis harsh ionizing environment.
| The ionizing star of the North America and Pelican nebulae
We present the results of a search for the ionizing star of the NorthAmerica (NGC 7000) and the Pelican (IC 5070) nebulae complex. Theapplication of adequate selection criteria to the 2MASS JH KSbroad-band photometry allows us to narrow the search down to 19preliminary candidates in a circle of 0o 5 radius containingmost of the L935 dark cloud that separates both nebulae. Follow-upnear-infrared spectroscopy shows that most of these objects are carbonstars and mid-to-late-type giants, including some AGB stars. Two of thethree remaining objects turn out to be later than spectral type B andthus cannot account for the ionization of the nebula, but a thirdobject, 2MASS J205551.25+435224.6, has infrared properties consistentwith it being a mid O-type star at the distance of the nebulae complexand reddened by AV ≃ 9.6. We confirm its O5V spectraltype by means of visible spectroscopy in the blue. This star has thespectral type required by the ionization conditions of the nebulae andphotometric properties consistent with the most recent estimates oftheir distance. Moreover, it lies close to the geometric center of thecomplex that other studies have proposed as the most likely location forthe ionizing star, and is also very close to the position inferred fromthe morphology of cloud rims detected in radio continuum. Given thefulfillment of all the conditions and the existence of only one star inthe whole search area that satisfies them, we thus propose 2MASSJ205551.25+435224.6 as the ionizing star of the North America/Pelicancomplex.Based on observations collected at the Centro AstronómicoHispano-Alemán (CAHA) at Calar Alto, operated jointly by theMax-Planck Institut für Astronomie and the Instituto deAstrofísica de Andalucía (CSIC).Figure 1 is only available in electronic form athttp://www.edpsciences.org
| HH 666: The Axis of Evil in the Carina Nebula
We report the discovery of the iniquitous parsec-scale outflow HH666-the first protostellar jet in the Carina Nebula-as well as theinfrared identification of its embedded driving source. The HH 666 jetemanates from a bright-rimmed molecular globule (G287.57-0.91) at thehead of a dust pillar in the southern part of Carina. Optical andnear-infrared images reveal structures that resemble bow shocks andinternal working surfaces in other Herbig-Haro (HH) jets, and which areespecially bright in [Fe II] λ16435. Except for extended bowshock wings, all features lie within a few degrees of a single axisoriented roughly southeast to northwest, with a remarkable highlycollimated flow breaking out of the natal globule. Long-slit echellespectra reveal only redshifted velocities toward the southeast of theglobule and blueshifted velocities toward the northwest. The observedfeatures conspire to form a single, coherent bipolar jet with a totalprojected length of over 4.5m, or more than 3 pc. Doppler shifts ashigh as +/-250 km s-1 are seen, indicating that the jet axishas a significant tilt from the plane of the sky, and the total lengthof the jet may be closer to 4 or 5 pc. HH 666 is therefore among thelongest HH jets known. Condemned to toil in the inferno of the CarinaNebula, scorched by UV radiation from the hot stars that power the H IIregion, much of the jet is influenced by radiative excitation. Infraredimages reveal a reddened star embedded in the molecular globule lyingalong the jet axis. We identify this evildoer (HH 666 IRS) as the likelydriving source of the jet. The infrared spectral energy distribution ofHH 666 IRS is consistent with that of a Class I protostellar object,with a luminosity of a few hundred to 103 Lsolar,and a probable main-sequence mass of a few to 8 Msolar. ThisClass I object associated with a prominent bipolar jet constitutes thefirst direct evidence of ongoing active star formation by accretion inthe Carina Nebula.
| The Origin of the Galactic Center Nonthermal Radio Filaments: Young Stellar Clusters
The unusual class of magnetized nonthermal radio filaments, threads, andstreaks, with their unique physical characteristics, is found onlywithin the inner couple of degrees of the Galactic center. Also, anumber of young, mass-losing, and rare stellar clusters are recognizedas lying in the Galactic center region. The latter characteristic of theGalactic center region is used to explain the origin of the nonthermalradio filaments. We consider a mechanism in which the collective windsof massive W-R and OB stars within a dense stellar environment produceshock waves that can accelerate particles to relativistic energies. Thismechanism is an extension of a model originally proposed in 1996 byRosner & Bodo, who suggested that energetic nonthermal particles areproduced in a terminal shock of mass-losing stars. The large-scaledistribution of the magnetic field in the context of this model isargued to be neither poloidal in geometry nor pervasive throughout theGalactic center region.
| Irradiated Jets and Outflows in the Pelican Nebula
We report the discovery of new Herbig-Haro objects in the Pelican Nebula(IC 4050). HH 555 is a bipolar jet emerging from the tip of a majorelephant trunk protruding into the Pelican Nebula from the adjacentmolecular cloud. Both beams of HH 555 bend toward the west, indicatingdeflection by a side wind. A chain of three nearly equally spaced bowshocks, HH 563, HH 564, and HH 565, trace a bent flow bursting out ofthe southern rim of the Pelican molecular cloud, possibly driven by themoderate-luminosity Class I protostar IRAS 20489+4406. Object HH 570 isa highly collimated jet emerging from a compact cloud located about 15'southeast of the Pelican molecular cloud. A parallel outflow, possiblydriven by IRAS 20496+4354, powers the bright bow shock HH 569. Theseobservations demonstrate that vigorous star formation is still occurringwithin the clouds that surround the evolved North America/Pelican Nebulacomplex.
| Structure Function Scaling of a 2MASS Extinction Map of Taurus
We compute the structure function scaling of a 2MASS extinction map ofthe Taurus molecular cloud complex. The scaling exponents of thestructure functions of the extinction map follow Boldyrev's velocitystructure function scaling of supersonic turbulence. This confirms ourprevious result based on a spectral map of 13CO J=1-0covering the same region and suggests that supersonic turbulence isimportant in the fragmentation of this star-forming cloud.
| Milestones in the Observations of Cosmic Magnetic Fields
Magnetic fields are observed everywhere in the universe. In this review,we concentrate on the observational aspects of the magnetic fields ofGalactic and extragalactic objects. Readers can follow the milestones inthe observations of cosmic magnetic fields obtained from the mostimportant tracers of magnetic fields, namely, the star-lightpolarization, the Zeeman effect, the rotation measures (RMs,hereafter)of extragalactic radio sources, the pulsar RMs, radio polarizationobservations, as well as the newly implemented sub-mm and mmpolarization capabilities. The magnetic field of the Galaxy was firstdiscovered in 1949 by optical polarization observations. The localmagnetic fields within one or two kpc have been well delineated bystarlight polarization data. The polarization observations of diffuseGalactic radio background emission in 1962 confirmed unequivocally theexistence of a Galactic magnetic field.The bulk of the presentinformation about the magnetic fields in the Galaxy comes from analysisof rotation measures of extragalactic radio sources and pulsars, whichcan be used to construct the 3-D magnetic field structure in theGalactic halo and Galactic disk. Radio synchrotron spurs in the Galacticcenter show a poloidal field, and the polarization mapping of dustemission and Zeeman observation in the central molecular zone reveal atoroidal magnetic field parallel to the Galactic plane. For nearbygalaxies, both optical polarization and multifrequency radiopolarization data clearly show the large-scale magnetic field followingthe spiral arms or dust lanes. For more distant objects, radiopolarization is the only approach available to show the magnetic fieldsin the jets or lobes of radio galaxies or quasars. Clusters of galaxiesalso contain widely distributed magnetic fields, which are reflected byradio halos or the RM distribution of background objects. Theintergalactic space could have been magnetized by outflows or galacticsuperwinds even in the early universe. The Zeeman effect andpolarization of sub-mm and mm emission can be used for the study ofmagnetic fields in some Galactic molecular clouds but it is observedonly at high intensity. Both approaches together can clearly show therole that magnetic fields play in star formation and cloud structure,which in principle would be analogous to galaxy formation fromprotogalactic clouds. The origin of the cosmic magnetic fields is anactive field of research. A primordial magnetic field has not been asyet directly detected, but its existence must be considered to give theseed field necessary for many amplification processes that have beendeveloped. Possibly, the magnetic fields were generated in protogalacticplasma clouds by the dynamo process, and maintained again by the dynamoafter galaxies were formed.
| Hα Emission Stars and Herbig-Haro Objects in the Vicinity of Bright-rimmed Clouds
Bright-rimmed clouds (BRCs) found in H II regions are probably sites oftriggered star formation due to compression by ionization/shock fronts.Many BRCs harbor IRAS point sources of low dust temperature. They alsofrequently contain a small cluster of near-IR stars that is elongatedalong the axis of the BRC. Here we present the results of our Hαgrism spectroscopy and narrowband imaging observations of BRCs in searchof candidate pre-main-sequence stars of the T Tauri, Herbig Ae/Be andrelated types, and Herbig-Haro (HH) objects. We have detected a largenumber (460) of Hα emission stars down to a limiting magnitude ofabout R=20 in and around all but two of the 28 BRCs observed. Thepresent study has, for the first time, reached down nearly to thefaintest classical T Tauri star population in OB associations. A totalof 12 new HH objects have been found. Most are of small apparent size,emphasizing the need for deep searches at high spatial resolution, butHH 588 associated with BRC 37 represents a huge HH complex composed oftwo-staged bow shocks on both sides of a tiny central knot. These starsand HH objects are concentrated near the tip of bright rims (i.e., inthe head of the BRCs and just outside the rims) and often make looseaggregates similar to those of near-IR stars, thus supporting ourhypothesis of ``small-scale sequential star formation.'' The presence ofsuch a large number of Hα emission stars in the immediatevicinities of BRCs implies that second-generation formation of low-massstars is relatively extensive and further supports the notion ofcohabitation of high- and low-mass populations in OB associations.
| Extinction with 2MASS: Star Counts and Reddening toward the North America and Pelican Nebulae
We propose a general method for mapping the extinction in densemolecular clouds using Two Micron All Sky Survey near-infrared data. Thetechnique is based on the simultaneous utilization of star counts andcolors. These two techniques provide independent estimations of theextinction, and each method reacts differently to foreground starcontamination and to star clustering. We take advantage of both methodsto build a large-scale extinction map (2.5d×2.5d) of the NorthAmerica and Pelican Nebulae complex. With Ks star counts andH-Ks color analysis the visual extinction is mapped up to 35mag. Regions with visual extinction greater than 20 mag account for lessthan 3% of the total mass of the cloud. Color is generally a betterestimator for the extinction than star counts. Nine star clusters areidentified in the area, seven of which were previously unknown.
| CCD Photometry and Classification of Stars in the North America and Pelican Nebulae Region. I. Molėtai Photometry
Magnitudes and color indices in the Vilnius seven-color system aremeasured for 690 stars down to ~ 13.2 mag in the area of the NorthAmerica and Pelican nebulae. Spectral types, absolute magnitudes, colorexcesses, interstellar extinctions and distances of the stars aredetermined. The plots of interstellar extinction A_V versus distance forthe North America Nebula and for the dark cloud L935 show that bothareas are covered by the same absorbing cloud, situated at a distance of600 pc. The maximal extinction in the area of the nebula is ~ 3 mag,while in the dark cloud L935 it is much greater.
| Near-infrared imaging of compact HII regions in Cygnus X
We present a near-infrared imaging survey of compact HII regions in thedirection of the Cygnus X complex, for which no previous observations atthose wavelengths have been published so far. The targets have beenselected from a catalog of sources in that region having a thermalspectral energy distribution between 408 and 4800 MHz (Wendker et al.1991), and an inferred angular size smaller than 5 arcmin across. Wepresent images in the JHK filters, color-magnitude, and color-colordiagrams for each region. We also suggest and apply a method forestimating the distance by comparing the dereddened H-band flux from allthe stars in the area of the HII region and the radio-continuum flux.Many of the regions imaged are clearly associated with stellaraggregates with different degrees of concentration, whose componentsshow varying amounts of extinction. Some objects are often found in theregion of the (J-H), (H-K) diagram indicating excess emission ofcircumstellar nature. A detailed discussion on each object is providedin the context of existing published observations at differentwavelengths, in particular regarding the existence of ultracompactcomponents. A number of ultracompact HII regions are found to haveclearly visible unresolved or nearly unresolved K-band counterpartscharacterized by very red H-K colors, suggesting that the extinction maybe low enough in their direction so as to allow the direct observationof the star ionizing the ultracompact component. Based on observationscollected at the Observatorio del Teide (Tenerife, Spain). The completeFig. 1 is available in electronic form at http://www.edpsciences.org andTable 2 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/375/539
| Superhumps in Cataclysmic Binaries. XX. V751 Cygni
We report photometric and spectroscopic observations of the nova-likevariable V751 Cygni. The radial velocities indicate an underlying binaryperiod of 0.1445(2) day; the long-term cycle count is not firmlydecided, but the best choice implies a period of 0.144464(1) day. Thestar shows a moderately low excitation spectrum with transient P Cygniabsorption suggestive of a wind origin, occasionally seen in cataclysmicvariables accreting at a high rate. Curiously, the P Cygni absorptionappears correlated with binary phase in our two most extensive datasets. A photometric wave with P=0.1394(1) day, slightly shorter thanPorb, rumbles through the light curve, as well as alow-frequency wiggle at 3.94(6) days. We identify the former as a``negative superhump'' and the latter as the wobble period of a tiltedaccretion disk. These characteristics all suggest classification as anordinary, accretion-powered cataclysmic variable of the VY Sculptorisclass. We discuss possible origins for the observed soft X-rays atquiescence.
| The Cepheid distance to M96 and the Hubble constant
HST WFPC2 observations of Cepheids in M96 (NGC 3368) are used to find adistance to that galaxy of 11.2+/-1.0Mpc. This estimate is based on acalibration of the Cepheid period-luminosity relation in the LargeMagellanic Cloud, and includes a correction for the difference inmetallicity between the two systems. There are good reasons forbelieving M96 is at the same distance as four E/S0 galaxies in the Leo-Igroup, and hence we calibrate secondary distance indicators based on theearly-type galaxies, namely the fundamental plane andsurface-brightness-fluctuation method. Also the Type Ia supernova 1998buoccurred in M96 itself and is used to calibrate the SN Ia distancescale. These methods reach to recession velocities of greater than5000kms-1 and can therefore allow us to evaluate the Hubbleconstant without reference to the peculiar velocity of M96 itself. Infact, these indicators agree well between themselves and hence we findH0=67+/-7kms-1Mpc-1 where the quotederror includes estimates of potential systematic effects.
| Photometry of V 1794 Cygni between 1975 and 1995
Six years of new photometry of V 1794 Cyg is combined with thepreviously published data. These data are processed into two decades ofhomogeneous standard Johnson UBVRI photometry, which contains 1207,1837, 1927, 867 and 75 observations in U, B, V, R and I, respectively.
| A study of the young star V1331 Cyg in a compact star forming region.
Not Available
| Interstellar Extinction Law in the Vicinity of the North America and Pelican Nebulae
The interstellar reddening law is derived for 15 heavily reddened starsin the area which includes the North America and Pelican nebulae and thedark cloud between them. The method is based on photometry of thesestars in the Vilnius seven-color system and on their MK spectral types.The mean law in this area is very similar to the law for a much widerarea in Cygnus derived earlier by other authors. It differs from thenormal law by exhibiting somewhat stronger extinction in the violet andthe near ultraviolet spectral region, i.e., it shows a smaller ``knee"in the blue part of the spectrum.
| A CO survey for high velocity gas in interstellar H2O maser sources.
Not Available
| POSS - the ultimate deep-sky resource?
The purpose of this paper is to look at the ways in which the POSSsurvey has become available to amateurs, enabling them to use it forobject checking and verification techniques previously only available tothe professional.
| Regions of Low-Mass Star Formation
The fundamental question of the relationship between the properties ofthe star-forming material and the resulting stellar population isaddressed in general. Some detail is given on star formation in the ChaIII cloud, the status of the isolated T Tauri stars, and on globules asplaces of star-forming activity.
| New 115-1115-1115-1objects in dark nebulae. II.
Results of a search for new emission objects in the region of darknebulae are presented. The observations were made in 1979 and 1985 atthe 40 Schmidt telescope of the Byurakan Astrophysical Observatory. Thespectra were obtained with a 4° objective prism (1100Å/mm nearH) on Kodak 103aE, 103aF, IIaF, and IIIaF plates with the use of RG1 andRG2 filters. Of the 52 emission stars discovered, five show variabilityin the H line intensity.
| Meet the Milky Way.
Not Available
| Briefly noted: Irish astronomy (poem)
Not Available
| The Large-Scale Structure, Kinematics, and Evolution of IC 1396
Abstract image available at:http://adsabs.harvard.edu/abs/1995ApJ...447..721P
| Uvbyβ photometry of Orion population stars and related objects associated with six star forming regions
Homogeneous uvbyβ photometry of 150 stars associated with the starforming regions Taurus-Auriga, Orion, Canis Mayoris, Ophiuchus, Serpensand Cygnus, is presented here. We also present uvbyβ photometry of10 Herbig Ae/Be stars not belonging to the specific regions studiedhere. Using the (V,b-y), (β,[m1]), ([c1],[m1]) and ([u-b], T_eff_)diagrams we study the photometric properties of the sample. The effectsof duplicity, stellar rotation, and interstellar extinction on thelocation in the magnitude-color and color-color diagrams of our programstars are briefly investigated. We derive reliable photometric spectraltypes and discuss membership to the regions and to the Orion population,as well as peculiarities of the individual stars. We also find new Bstars associated with the CMa R1 star forming region and newintermediate-low mass PMS members associated with theBD+404124/BD+413731 region. The FU-Orionis stars Z CMa, V1515 Cyg andV1057 Cyg have a peculiar position in the reddening free (β,[m1])diagram. With diagrams such as (V-M _v_-5 log r+5) vs. E(b-y), E(c1) vs.E(b-y), E(m1) vs. E(b-y) and E(u-b) vs. E(b-y) we investigate the ISextinction law towards the star-forming regions. We find that the totalto selective extinction ratio to these regions is steeper than normalwith R_y_=5.4 (R_v_=4.0) and the coefficients E(c1)/E(b-y) andE(m1)/E(b-y) used to define the reddening free indices [c1] and [m1]should be numerically smaller than the generally adopted values.
| Glittering realms of the summer Milky Way.
Not Available
| New H-alpha-emission objects in the Cepheus region.
Not Available
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