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We cannot assign a meaningful uncertainty (to this or the other numerical results from the dynamical model solution because our A? measure of fit is dominated by a few large discrepancies. and some (such as the four misfit galaxies in Figs.
We cannot assign a meaningful uncertainty to this or the other numerical results from the dynamical model solution because our $\chi^2$ measure of fit is dominated by a few large discrepancies, and some (such as the four misfit galaxies in Figs.
9 to 5)) certainly represent svstematic errors in the model.
\ref{Fig:3} to \ref{Fig:5}) ) certainly represent systematic errors in the model.
That is. our A7 measure has no formal significance.
That is, our $\chi^2$ measure has no formal significance.
We can point out that the model value was eom241 km | in the solution with 10 LG galaxies (plus the 4 external actors) and. ο increased as more distant galaxies were added to the solution.
We can point out that the model value was $v_c=241$ km $^{-1}$ in the solution with 10 LG galaxies (plus the 4 external actors) and $v_c$ increased as more distant galaxies were added to the solution.
That is. the larger value of ve in the final model changed the relation between heliocentric ancl galactocentric redshilts in the direction wanted to aid the fit to the redshifts of more distant LG galaxies.
That is, the larger value of $v_c$ in the final model changed the relation between heliocentric and galactocentric redshifts in the direction wanted to aid the fit to the redshifts of more distant LG galaxies.
This means that if ος proved to be close to the standard. value. 220 kms |. the challenge to the model likely would not be related to the problematic orbits of (he nearer galaxies M33 and 110.
This means that if $v_c$ proved to be close to the standard value, $220$ km $^{-1}$, the challenge to the model likely would not be related to the problematic orbits of the nearer galaxies M33 and IC10.
The computation allows (he present positions of the particles to be offset. [rom the observed positions of the galaxies on (wo considerations. that the approximate model should be allowed some error in this direction and that this affords an indication of whether the dark matter around a galaxy mav be signilicantlv displaced from the stars.
The computation allows the present positions of the particles to be offset from the observed positions of the galaxies on two considerations, that the approximate model should be allowed some error in this direction and that this affords an indication of whether the dark matter around a galaxy may be significantly displaced from the stars.
The generally small values of the olfsets D. in Table 1 mean we have no evidence that the stars are not well centered on the dark matter. but tighter constraints on the model errors are neecled [or a significant exploration of this important issue.
The generally small values of the offsets $D_\perp$ in Table 1 mean we have no evidence that the stars are not well centered on the dark matter, but tighter constraints on the model errors are needed for a significant exploration of this important issue.
Figure 6 shows the evolution of positions relative to MW olf the five galaxies now closest to MW.
Figure \ref{Fig:orbits} shows the evolution of positions relative to MW of the five galaxies now closest to MW.
The coordinates are galactic aud (he lengths are physical.
The coordinates are galactic and the lengths are physical.
Positions at redshilt :=1
Positions at redshift $z=1$
Open clusters constitute an. important. part of à process transforming gas and dust into stars.
Open clusters constitute an important part of a process transforming gas and dust into stars.
They are observed as the most prominent parts in the regions of active star formation. or às tracers of the ceased star formation process in the general Galactic field.
They are observed as the most prominent parts in the regions of active star formation, or as tracers of the ceased star formation process in the general Galactic field.
However. the role they are playing in this process has still not been fully understood.
However, the role they are playing in this process has still not been fully understood.
In spite of their prominence. there are indications that classical open clusters contribute only or even less input (222) to the total stellar population of the Galactic disc.
In spite of their prominence, there are indications that classical open clusters contribute only or even less input \citep{wiel71,misca78,clupop} to the total stellar population of the Galactic disc.
This contradiction can be explained either by an early decay of a considerable fraction of newly formed star clusters (seee.g.2???) or by an insufficient knowledge of cluster formation statistics.
This contradiction can be explained either by an early decay of a considerable fraction of newly formed star clusters \citep[see e.g.][]{tut78,kah01,lamea} or by an insufficient knowledge of cluster formation statistics.
In this context. one should note that the most important items of cluster formation like the distribution of cluster masses at birth (1.e.. the initial mass function of star clusters) and the cluster formation rate are still poorly known.
In this context, one should note that the most important items of cluster formation like the distribution of cluster masses at birth (i.e., the initial mass function of star clusters) and the cluster formation rate are still poorly known.
Even in the close vicinity of the Sun. the only attempt to construct the luminosity function of open clusters (2) 1s based on a sample of 142 clusters that. according to the authors. is to 2/3 complete within 400 pe.
Even in the close vicinity of the Sun, the only attempt to construct the luminosity function of open clusters \citep{vdblaf84} is based on a sample of 142 clusters that, according to the authors, is to 2/3 complete within 400 pc.
A mass function of Galactic open clusters Is not yet available.
A mass function of Galactic open clusters is not yet available.
In contrast. extragalactic cluster populations have been actively investigated. especially during the present decade.
In contrast, extragalactic cluster populations have been actively investigated, especially during the present decade.
The lummosity functions of remote clusters are determined both in active and regular galaxies (seee.g.999andreferences therein)...
The luminosity functions of remote clusters are determined both in active and regular galaxies \citep[see e.g.][ and references therein]{slars,grijs03,giel06}.
For some galaxies. luminosity distributions of open clusters are converted to the mass functions via the assumed theoretical mass-luminosity relation (?)..
For some galaxies, luminosity distributions of open clusters are converted to the mass functions via the assumed theoretical mass-luminosity relation \citep{zhang99}.
Using extragalactic data for the study of cluster population gives certain advantages.
Using extragalactic data for the study of cluster population gives certain advantages.
When observing external galaxies. one is able to cover large areas of their surfaces and catch the brightest objects. which are intrinsically rare.
When observing external galaxies, one is able to cover large areas of their surfaces and catch the brightest objects, which are intrinsically rare.
This ts rather difficult in the case of our own Galaxy since they could be hidden by a dusty environment.
This is rather difficult in the case of our own Galaxy since they could be hidden by a dusty environment.
Also. different selection effects can be taken into account better in an external galaxy because its clusters are located at about the same distance from the Sun.
Also, different selection effects can be taken into account better in an external galaxy because its clusters are located at about the same distance from the Sun.
Moreover. studies of extragalactic clusters give à key to our understanding of the cluster formation in different environments.
Moreover, studies of extragalactic clusters give a key to our understanding of the cluster formation in different environments.
However. there are a number of problems related to studies based on extragalactic clusters.
However, there are a number of problems related to studies based on extragalactic clusters.
Samples of extragalactic clusters are restricted to relatively bright objects.
Samples of extragalactic clusters are restricted to relatively bright objects.
There is a danger of a contamination of cluster samples by brightest stars and of losing sparse objects in the strong background.
There is a danger of a contamination of cluster samples by brightest stars and of losing sparse objects in the strong background.
For example. ? finds that his sample in NGC6949 is contaminated to about by bright stars.
For example, \citet{slars} finds that his sample in NGC6949 is contaminated to about by bright stars.
The major problem is the necessity of transforming the observed luminosities into cluster masses.
The major problem is the necessity of transforming the observed luminosities into cluster masses.
The corresponding transformations are mainly based on the luminosity of a dozen of the most massive stars. whereas cluster masses are defined by numerous stars of lower masses that are below the observing limit.
The corresponding transformations are mainly based on the luminosity of a dozen of the most massive stars, whereas cluster masses are defined by numerous stars of lower masses that are below the observing limit.
In our study of the local population of Galactic open clusters. we obtained data that now allow a reliable construction of their lummosity and mass functions.
In our study of the local population of Galactic open clusters, we obtained data that now allow a reliable construction of their luminosity and mass functions.
Our cluster sample contains 641 open clusters and 9 associations identified in the all-sky compiled catalogue (?)..
Our cluster sample contains 641 open clusters and 9 associations identified in the all-sky compiled catalogue \citep{kha01}.
For each cluster we determined a homogeneous set of cluster parameters including. among others. its distance. age. and tidal mass.
For each cluster we determined a homogeneous set of cluster parameters including, among others, its distance, age, and tidal mass.
The sample is found to be complete up to a distance of about 850 pe from the Sun (?)..
The sample is found to be complete up to a distance of about 850 pc from the Sun \citep[]{clupop}. .
This completeness limit corresponds to a distance modulus (V—My) of about 10-10.5 (2) and allow probes of the luminosity function of open clusters that are much deeper than in other galaxies.
This completeness limit corresponds to a distance modulus $(V-M_V)$ of about 10--10.5 \citep[]{clusim} and allow probes of the luminosity function of open clusters that are much deeper than in other galaxies.
In this paper we aim at constructing the luminosity and mass functions of the Galactic open clusters and at comparing them to the data in other galaxies in order to touch the issue of universality of the. cluster formation process in. different environments.
In this paper we aim at constructing the luminosity and mass functions of the Galactic open clusters and at comparing them to the data in other galaxies in order to touch the issue of universality of the cluster formation process in different environments.
We also consider temporal variations of the two distributions.
We also consider temporal variations of the two distributions.
The ultimate purpose of this study is to construct the initial luminosity and mass distributions of star clusters independent of model assumptions on the M/L-ratio. to derive their parameters (the shape and limits). and to draw conclusionson the impact of these results on our understanding of the role
The ultimate purpose of this study is to construct the initial luminosity and mass distributions of star clusters independent of model assumptions on the M/L-ratio, to derive their parameters (the shape and limits), and to draw conclusionson the impact of these results on our understanding of the role
To investigate which. components of the spectrum are phase dependent. the four spectra were fitted with the model discussed above. keeping the parameters corresponding to the 4U 0142-614 contamination and to the Fe-line fixed.
To investigate which components of the spectrum are phase dependent, the four spectra were fitted with the model discussed above, keeping the parameters corresponding to the 4U 0142+614 contamination and to the Fe-line fixed.
The results are reported in Table 2.
The results are reported in Table 2.
Significant variations are seen in the power law spectral index and absorption. while the errors in the cut-off parameters are too large to establish a definite variation in the different pulse phase intervals.
Significant variations are seen in the power law spectral index and absorption, while the errors in the cut-off parameters are too large to establish a definite variation in the different pulse phase intervals.
Note that during phase interval D. we obtain an upper limit to the photoelectric absorption lower than the value expected for from optical observations (Motch et al.
Note that during phase interval D, we obtain an upper limit to the photoelectric absorption lower than the value expected for from optical observations (Motch et al.
1997).
1997).
This is an indication that the model used is oversimplified and more spectral components are probably required. at least at certain phase intervals.
This is an indication that the model used is oversimplified and more spectral components are probably required, at least at certain phase intervals.
We have analyzed the data from the the Low-Energy Concentrator Spectrometer (LECS: 0.1-10 keV: Parmar et al.
We have analyzed the data from the the Low–Energy Concentrator Spectrometer (LECS; 0.1–10 keV; Parmar et al.
1997) and Medium—Energy Concentrator Spectrometer (MECS: 1.3-10 keV: Boella et al.
1997) and Medium–Energy Concentrator Spectrometer (MECS; 1.3–10 keV; Boella et al.
1997b).
1997b).
The MECS instrument consists of three identical grazing incidence telescopes with imaging gas scintillation proportional counters in their focal planes.
The MECS instrument consists of three identical grazing incidence telescopes with imaging gas scintillation proportional counters in their focal planes.
The LECS instrument uses an identical concentrator system as the MECS. but utilizes an ultra- (1.25 jm) detector entrance window and a driftless configuration to extend the low-energy response to 0.1 keV. The fields of view of the LECS and MECS are circular with diameters of aand respectively.
The LECS instrument uses an identical concentrator system as the MECS, but utilizes an ultra--thin (1.25 $\mu$ m) detector entrance window and a driftless configuration to extend the low–energy response to 0.1 keV. The fields of view of the LECS and MECS are circular with diameters of and respectively.
The energy resolution of both instruments 15 ~8.5 VIOΊων FWHM.
The energy resolution of both instruments is $\sim$ $\sqrt{6/{\rm E_{keV}}}$ FWHM.
In the overlapping energy range. the angular resolution of both instruments is similar. and corresponds to encircled energy within a radius of 2/55 at 1.5 keV. The position ts included at various offset angles in four oobservations of 001424614 (see 33).
In the overlapping energy range, the angular resolution of both instruments is similar and corresponds to encircled energy within a radius of 5 at 1.5 keV. The position is included at various offset angles in four observations of 0142+614 (see 3).
The original project was to monitor in order to remove the high energy contribution of this pulsar from. that. of 001424614 in the non-imaging instruments.
The original project was to monitor in order to remove the high energy contribution of this pulsar from that of 0142+614 in the non–imaging instruments.
The spectral and timing results we obtained for 001424614 are reported elsewhere (Israel 19992).
The spectral and timing results we obtained for 0142+614 are reported elsewhere (Israel 1999a).
After the first observation. one of the three MECS units failed (1997 May 9) and the data of the following pointings were obtained through the remaining two MECS units.
After the first observation, one of the three MECS units failed (1997 May 9) and the data of the following pointings were obtained through the remaining two MECS units.
Spectra were extracted from circular regions with radius of ffor both the LECS and MECS instruments and rebinned so as to have 30 counts in each energy bin to allow the use of 4? statistics.
Spectra were extracted from circular regions with radius of for both the LECS and MECS instruments and rebinned so as to have $>$ 30 counts in each energy bin to allow the use of $\chi^2$ statistics.
Spectral response matrices appropriate to the particular source off-axis positions were used.
Spectral response matrices appropriate to the particular source off–axis positions were used.
These matrices include also a correction for the presence of the strongback used to support the detector entrance window.
These matrices include also a correction for the presence of the strongback used to support the detector entrance window.
The background subtraction was performed using source-free regions of each observation at the appropriate off-axis and azimuth angle (to
The background subtraction was performed using source–free regions of each observation at the appropriate off–axis and azimuth angle (to
online tools described by ?..
online tools described by \citet{Eastman2010}.
Aperture sizes were optimized by minimizing the scatter of the resulting light curves, and ranged from 3" to 6".
Aperture sizes were optimized by minimizing the scatter of the resulting light curves, and ranged from 3" to 6".
Exposure times were typically 300s.
Exposure times were typically 300s.
however. be an overestimate. because the envelope structure is not axisymmetric in reality.
however, be an overestimate, because the envelope structure is not axisymmetric in reality.
Owing to the similarity of the contnuum spectra. we expect L1041 and L1527 to have a similar physical structure.
Owing to the similarity of the continuum spectra, we expect L1041 and L1527 to have a similar physical structure.
Varying depths of ice absorptions among these objects would thus probe the difference in the ice composition ineec the envelope.
Varying depths of ice absorptions among these objects would thus probe the difference in the ice composition in the envelope.
The SED modeling of the YSOs suggests that the envelope of IRASO4302 is slightly less dense than L1527 (Furlan et al. 2008)).
The SED modeling of the YSOs suggests that the envelope of IRAS04302 is slightly less dense than L1527 (Furlan et al. \cite{furlan08}) ).
We found smaller column densities of tces and lower CO/CO» 1ce ratios towards IRASO4302 than L1527. which also indicates that IRASO4302 is more evolved and has a less massive envelope.
We found smaller column densities of ices and lower $_2$ ice ratios towards IRAS04302 than L1527, which also indicates that IRAS04302 is more evolved and has a less massive envelope.
Although our observations probe ice 1n. envelopes rather than disks. the envelope material along our lines of sight (perpendicular to the rotation axis and outflow) is more likely to end up in the forming disks than be dissipated in the clouds.
Although our observations probe ice in envelopes rather than disks, the envelope material along our lines of sight (perpendicular to the rotation axis and outflow) is more likely to end up in the forming disks than be dissipated in the clouds.
The high CO/CO: ice ratio indicates that the majority of gases in the lines of sight are still dense and cold.
The high $_2$ ice ratio indicates that the majority of gases in the lines of sight are still dense and cold.
The CO:/H»O ratio towards our objects is similar to the ratio observed by Pontoppidan et al. (2008)).
The $_2$ $_2$ O ratio towards our objects is similar to the ratio observed by Pontoppidan et al. \cite{pontoppidan2008}) ),
who observed low-mass YSOs with various inclinations: the CO;/H:O ratio does not seem to vary with the inclination angle.
who observed low-mass YSOs with various inclinations; the $_2$ $_2$ O ratio does not seem to vary with the inclination angle.
The CO gas absorption and deep absorption feature of OCN .on the other hand. would originate in the warm (T>20 K) and irradiated region near the protostar.
The CO gas absorption and deep absorption feature of $^-$, on the other hand, would originate in the warm $T\ge 20$ K) and irradiated region near the protostar.
However. other signs of heating by the protostar. such as erystalline feature of H?O ice (Schegerer Wolf 2010)) and CO» gas. are not found in our data.
However, other signs of heating by the protostar, such as crystalline feature of $_2$ O ice (Schegerer Wolf \cite{schegerer10}) ) and $_2$ gas, are not found in our data.
We may need higher spatial resolution and spectral resolution to detect these features.
We may need higher spatial resolution and spectral resolution to detect these features.
We estimated the H»O ice column density from. our observations to be 7.8x10' emo? towards ASR41 and 6.7x10" em towards 2MASS 11628137.
We estimated the $_2$ O ice column density from our observations to be $7.8 \times 10^{17}$ $^{-2}$ towards ASR41 and $6.7\times 10^{17}$ $^{-2}$ towards 2MASS J1628137.
These values are apparently much lower than we expect from the theoretical prediction of high H»O ice abundance n(H;OJ/ny ~107 in the disk midplane.
These values are apparently much lower than we expect from the theoretical prediction of high $_2$ O ice abundance $_2$ $_{\rm H}$ $\sim 10^{-4}$ in the disk midplane.
The shallow absorption is. however. caused by a geometric effect.
The shallow absorption is, however, caused by a geometric effect.
Pontoppidan et al. (2005))
Pontoppidan et al. \cite{crbr05}) )
predicts that the 3 uim water band is the deepest for the disk inclination of ~70° and becomes shallower for higher inclination angles.
predicts that the 3 $\mu$ m water band is the deepest for the disk inclination of $\sim 70^{\circ}$ and becomes shallower for higher inclination angles.
If the inclination angle i$ >72°. the optical depth of the band is predicted to be ~0.6. which is comparable to our observation of ASR41.
If the inclination angle is $\ge 72^{\circ}$, the optical depth of the band is predicted to be $\sim 0.6$, which is comparable to our observation of ASR41.
Since the light source (scattered stellar light) is more extendec than the absorbing material. Eq. (2) underestimates the ice column density towards edge-on disks.
Since the light source (scattered stellar light) is more extended than the absorbing material, Eq, (2) underestimates the ice column density towards edge-on disks.
Possible contributions to the observed ice column densities from foreground clouds should also be considered.
Possible contributions to the observed ice column densities from foreground clouds should also be considered.
In the Taurus molecular cloud. the average H:O abundance is about 8.6x107 relative to hydrogen nuclei at A,>3 mag (Whittet et al. 1993:;
In the Taurus molecular cloud, the average $_2$ O abundance is about $8.6\times 10^{-5}$ relative to hydrogen nuclei at $A_{\rm v} \ge 3$ mag (Whittet et al. \cite{whittet93};
Chair et al. 2011)).
Chair et al. \cite{chair11}) ).
The HO ice is not detected at lower A,. which indicates that HO ice is easily destroyed by pphotolysis or photodesorption near the cloud surface.
The $_2$ O ice is not detected at lower $A_{\rm v}$, which indicates that $_2$ O ice is easily destroyed by photolysis or photodesorption near the cloud surface.
Hodapp et al. (2004))
Hodapp et al. \cite{hodapp04}) )
estimated that the density and size of the molecular cloud around ASR 41 are 2.0%1077? ¢em™ and 104 AU. which corresponds to Ay~1 mag.
estimated that the density and size of the molecular cloud around ASR 41 are $2.0 \times 10^{-20}$ g $^{-3}$ and $10^4$ AU, which corresponds to $A_{\rm V}\sim 1$ mag.
Although the relative abundance and the threshold A, varies from cloud to cloud. the column density of the foreground gas towards ASR41. A,-| mag. is too small to contribute significantly to the HO ice absorption band.
Although the relative abundance and the threshold $A_{\rm v}$ varies from cloud to cloud, the column density of the foreground gas towards ASR41, $A_{\rm v}\sim 1$ mag, is too small to contribute significantly to the $_2$ O ice absorption band.
Therefore. the observed HO ice most likely originates in the disk around ASRAT.
Therefore, the observed $_2$ O ice most likely originates in the disk around ASR41.
The foreground visual extinction towards 2MASSJ1628137. on the other hand. is estimated to be Ay=2.]--2.6 mag (Grosso et al.
The foreground visual extinction towards 2MASSJ1628137, on the other hand, is estimated to be $A_{\rm V}=2.1\pm 2.6$ mag (Grosso et al.
2003. ).
\cite{grosso03} ).
Assuming that the H2O ice abundance and threshold A, are the same as in Taurus. the upper limit of the foreground H?O ice column density ts ~2xI0 em, which is smaller than the observed HO ice column (6.7x10!" cm).
Assuming that the $_2$ O ice abundance and threshold $A_{\rm v}$ are the same as in Taurus, the upper limit of the foreground $_2$ O ice column density is $\sim 2 \times 10^{17}$ $^{-2}$, which is smaller than the observed $_2$ O ice column $6.7 \times 10^{17}$ $^{-2}$ ).
Hence. we conclude that most or all of the H:O ice observed towards 2MASSJ1628137 originates in the disk.
Hence, we conclude that most or all of the $_2$ O ice observed towards 2MASSJ1628137 originates in the disk.
HV Tau and HK Tau are multiple systems.
HV Tau and HK Tau are multiple systems.
As the separation between the multiple components in these systems is smaller than the size of our PSF in the NIR. we cannot extract the spectra of the faint edge-on objects.
As the separation between the multiple components in these systems is smaller than the size of our PSF in the NIR, we cannot extract the spectra of the faint edge-on objects.
Terada et al. (2007)
Terada et al. \cite{terada07}) )
observed 2—2.5 ym and 3—4 qmm spectra of these edge- objects using Subaru and detected deep water absorption (T~|— 1.5).
observed $2-2.5$ $\mu$ m and $3-4$ $\mu$ m spectra of these edge-on objects using Subaru and detected deep water absorption $\tau\sim 1-1.5$ ).
The continuum flux of HV Tau C is ~7.75 my at 2.2 um and ~7.14 mJy at 3.8 jm. while the flux of HK Tau B Is —15.9 mJy at 2.2 jm and ~9.85 mJy at 3.8 jm. Apparently. our spectra are dominated by the bright primaries.
The continuum flux of HV Tau C is $\sim 7.75$ mJy at 2.2 $\mu$ m and $\sim 7.14$ mJy at 3.8 $\mu$ m, while the flux of HK Tau B is $\sim 15.9$ mJy at 2.2 $\mu$ m and $\sim 9.85$ mJy at 3.8 $\mu$ m. Apparently, our spectra are dominated by the bright primaries.