scholarly journals Estimation of absolute magnitude-dependent Galactic model parameters in intermediate latitude with SDSS and SCUSS

2014 ◽  
Vol 441 (1) ◽  
pp. 503-512 ◽  
Author(s):  
Yunpeng Jia ◽  
Cuihua Du ◽  
Zhenyu Wu ◽  
Xiyan Peng ◽  
Jun Ma ◽  
...  
Keyword(s):  
Absolute Magnitude ◽  
Model Parameters ◽  
Galactic Model

scholarly journals Volume-Limited Dependent Galactic Model Parameters

2007 ◽  
Vol 24 (4) ◽  
pp. 208-219 ◽  
Author(s):  
S. Karaali ◽  
S. Bilir ◽  
E. Yaz ◽  
E. Hamzaoğlu ◽  
R. Buser
Keyword(s):  
Axial Ratio ◽  
Absolute Magnitude ◽  
Model Parameters ◽  
Continuous Transition ◽  
Space Density ◽  
Thick Disc ◽  
The Galaxy ◽  
Galactic Model ◽  
Local Space ◽  
Galactic Longitude

AbstractWe estimate 34 sets of Galactic model parameters for three intermediate-latitude fields with Galactic longitudes l = 60°, l = 90°, and l = 180°, and we discussed their dependence on the volume. Also, we confirm the variation of these parameters with absolute magnitude and Galactic longitude. The star samples in two fields are restricted with bright and unit absolute-magnitude intervals, 4 < Mg ≤ 5, and 5 < Mg ≤ 6, whereas for the third field (l = 60°) a larger absolute-magnitude interval is adopted, 4 < Mg ≤ 10. The limiting apparent magnitudes of the star samples are g0 = 15 and g0 = 22.5 mag, which provide space densities within distances in the line of sight of ∼0.9 and 25 kpc.The Galactic model parameters for the thin disc are not volume dependent. However, the ones for the thick disc and halo do show spectacular trends in their variation with volume, except for the scalelength of the thick disc. The local space density of the thick disc increases, whereas the scaleheight of the same Galactic component decreases monotonically. However, both model parameters approach asymptotic values at large distances.The relative local space density of the halo estimated by fitting the density laws to the space densities evaluated for all volumes is constant, except for the small ones. However it is absolute-magnitude and Galactic longitude dependent. The axial ratio of the halo increases abruptly for the volumes where a thick disc is dominant, whereas it approaches an asymptotic value gradually for larger volumes, indicating a continuous transition from a disc-like structure to a spherical one at the outermost region of the Galaxy. The variation of the Galactic model parameters with absolute magnitude can be explained by their dependence on the stellar luminosity, whereas the variation with volume and Galactic longitude at short distances is a bias in analysis.

scholarly journals Estimation of Galactic Model Parameters In High Latitude With SDSS and SCUSS

2013 ◽  
Vol 9 (S298) ◽  
pp. 414-414
Author(s):  
Yunpeng Jia ◽  
Cuihua Du
Keyword(s):  
High Latitude ◽  
Absolute Magnitude ◽  
Galactic Structure ◽  
Thin Disk ◽  
Sloan Digital Sky Survey ◽  
Model Parameters ◽  
Structure Parameters ◽  
Sky Survey ◽  
Double Exponential ◽  
Galactic Model

AbstractUsing star counts method, we estimated the Galactic structure parameters in high latitude field (50° ≤ l ≤ 55°, −46° ≤ b ≤ −44°), 10 deg2 field with Sloan Digital Sky Survey (SDSS) and South Galactic Cap of U-band Sky Survey (SCUSS), to explore their possible variations with absolute magnitude. Here we just considered three components: double exponential thin disk and thick disk and a de Vaucouleurs halo. And these parameters were obtained by minimising χ2.

scholarly journals Estimation of Galactic Model Parameters by Interval Method

1996 ◽  
Vol 169 ◽  
pp. 713-714
Author(s):  
S. A. Kutuzov
Keyword(s):  
Mutual Interaction ◽  
Component Model ◽  
Model Parameters ◽  
Interval Method ◽  
Two Component ◽  
The Galaxy ◽  
Galactic Model

The interval method of estimating model parameters (MPs) for the Galaxy was suggested earlier (Kutuzov 1988). Intervals are proposed to be used both for observational estimates of galactic parameters (GPs) and for the values of MPs. In this work we consider a model as a tool for studying mutual interaction of GPs. Two-component model is considered (Kutuzov, Ossipkov 1989). We have to estimate the array P of eight MPs.

scholarly journals Estimation of Galactic model parameters in high latitudes with the SDSS and SCUSS

2013 ◽  
Vol 9 (S298) ◽  
pp. 404-404
Author(s):  
Cuihua Du ◽  
Yunpeng Jia ◽  
Xiyan Peng
Keyword(s):  
Model Parameters ◽  
High Latitudes ◽  
The South ◽  
Statistical Errors ◽  
Count Method ◽  
Sky Survey ◽  
Star Count ◽  
The Galaxy ◽  
Galactic Model

AbstractBased on the South Galactic Cap U-band Sky Survey (SCUSS) and SDSS observation, we adopted the star-count method to analyze the stellar distribution in different directions of the Galaxy. We find that these model parameters may be variable with observed direction, which cannot simply be attributed to statistical errors.

scholarly journals Identification of a new ultraluminous X-ray source in NGC 1316

2020 ◽  
Vol 499 (4) ◽  
pp. 5682-5689
Author(s):  
S Allak ◽  
A Akyuz ◽  
N Aksaker ◽  
M Ozdogan Ela ◽  
S Avdan ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Spectral Energy Distribution ◽  
Compact Object ◽  
Optical Emission ◽  
Absolute Magnitude ◽  
Spectral Energy ◽  
Model Parameters ◽  
Wide Field ◽  
X Ray ◽  
Blackbody Model

ABSTRACT In this study, we report identification of a new ultraluminous X-ray source (ULX) named as X-7 in NGC 1316, with an unabsorbed luminosity of 2.1 × 1039 erg s−1 using the two recent Chandra archival observations. The X-7 was detected in the Chandra 2001 observation and was included in the source list of the NGC 1316 as CXOUJ032240.8−371224 with a luminosity of 5.7 × 1038 erg s−1. Present luminosity implies a luminosity increase of a factor of ∼4. The best-fitting spectral model parameters indicate that X-7 has a relatively hot disc and hard spectra. If explained by a disc blackbody model, the mass of compact object is estimated as ∼8 M⊙ which is in the range of a stellar-mass black hole. The X-7 shows a relatively long-term count rate variability while no short-term variability is observed. We also identified a unique optical candidate within 0.22 arcsec error circle at 95 per cent confidence level for X-7 using the archival HST/ACS (Hubble Space Telescope/Advanced Camera for Surveys) and HST/WFC3 (The Wide Field Camera 3) data. Absolute magnitude (MV) of this candidate is −7.8 mag. Its spectral energy distribution is adequately fitted a blackbody model with a temperature of 3100 K indicating an M type supergiant, assuming the donor star dominates the optical emission. In addition, we identified a transient ULX candidate (XT-1) located 6 arcsec away from X-7 has a (high) luminosity of ∼1039 erg s−1 with no visible optical candidate.

scholarly journals Spatial distribution and galactic model parameters of cataclysmic variables

New Astronomy ◽  
2008 ◽  
Vol 13 (3) ◽  
pp. 133-143 ◽  
Author(s):  
T. Ak ◽  
S. Bilir ◽  
S. Ak ◽  
Z. Eker
Keyword(s):  
Spatial Distribution ◽  
Cataclysmic Variables ◽  
Model Parameters ◽  
Galactic Model
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