NGC 3898 (UGC 6787)

Галактика из диплома.

In [1]:
from IPython.display import HTML
from IPython.display import Image
import os

%matplotlib inline
%run ../../../utils/

Using matplotlib backend: Qt4Agg
Populating the interactive namespace from numpy and matplotlib

In [2]:
from photometry import *

importing Jupyter notebook from photometry.ipynb
Using matplotlib backend: Qt4Agg
Populating the interactive namespace from numpy and matplotlib

In [3]:
from instabilities import *

importing Jupyter notebook from instabilities.ipynb
Using matplotlib backend: Qt4Agg
Populating the interactive namespace from numpy and matplotlib

In [4]:
from utils import *

importing Jupyter notebook from utils.ipynb

In [5]:
name = 'N3898'
gtype = 'SA(s)ab'
incl = 70.  #(adopted by Epinat+2008)
scale = 0.092 #kpc/arcsec according to ApJ 142 145(31pp) 2011

data_path = '../../../data/ngc3898'
sin_i, cos_i = np.sin(incl*np.pi/180.), np.cos(incl*np.pi/180.)

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In [7]:

# Данные из NED
HTML('<iframe src=\
30000.0&list_limit=5&img_stamp=YES width=1000 height=350></iframe>')


In [8]:
# Данные из HYPERLEDA
HTML('<iframe src= width=1000 height=350></iframe>')


In [9]:
Image('ngc3898_SDSS.jpeg', width=300)


Картинка из выборки и там есть с маштабом изображение:

In [10]:
Image('ngc3898_SDSS_labeled.jpeg', width=500)


In [11]:
Image('ngc3898_JHK.jpg', width=300)


Есть пара картинок от HST, например вот, но не очень хороших.

Noordermeer thesis data:

Noordermeer, thesis, p. 113

UGC 6787 (NGC 3898) suffers from the same problem as UGC 6787: the luminous bulge distorts the isophotes of the disk out to large radii and the standard method to derive the inclination (section 3.5.1) cannot be used. Only after the model image of the bulge was subtracted could the disk ellipticity be determined. The final disk photometric profile and the intrinsic axis ratio of the bulge were derived using an inclination of $61^\circ$ . Note that this is still somewhat lower than the kinematic inclination derived from the HI velocity field (chapter 4)

Noordermeer, thesis, pp. 188-189

The rotation curve of UGC 6787 (NGC 3898) is well resolved and shows some characteristic ‘wiggles’ with an amplitude of 30 – 50 km/s. The kinematics in the central parts are only barely resolved in the optical spectrum, and due to the high inclination angle and resulting line-of-sight integration effects, the central line-profiles are strongly broadened. After the initial rise of the rotation curve to the peak velocity of 270 km/s, the rotation velocities drop to approximately 220 km/s at a radius of 3000 (∼ 2.75 kpc), after which they gradually rise again to 250 km/s at R ≈ 10000 (∼9 kpc). The rotation velocities then drop again to 220 km/s, after which they rise again to reach a more or less flat plateau at 250 km/s. Although there are clear indications that the gas disk of UGC 6787 is warped, the locations of the ‘wiggles’ in the rotation curve do not coincide with the radii where the position angle and the inclination change and the variations in the rotation velocity seem to be real. This is further confirmed by the fact that the variations occur symmetrically at all position angles over the velocity field. The discrepancy between the kinematic inclination angle derived here and the optical inclination from chapter 3 can be explained by the dominance of the bulge in the optical image. As was noted in chapter 3, the optical image of this galaxy is dominated by the spheroidal bulge out to large radii, which makes it impossible to obtain a reliable estimate for the inclination. The kinematical inclination derived here is free of such effects and thus reflects the true orientation of this galaxy more accurately.

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