Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.atnf.csiro.au/pasa/18_2/young1/paper/node4.html
Äàòà èçìåíåíèÿ: Fri Apr 8 09:15:22 2016
Äàòà èíäåêñèðîâàíèÿ: Sun Apr 10 16:05:06 2016
Êîäèðîâêà:
Ïîèñêîâûå ñëîâà: âíåøíèå ïëàíåòû
Bright galaxy sample (14th-8th mag.)

Total Magnitudes of Virgo Galaxies. I.
Construction of a Self-consistent Reference Dataset
Spanning 8th to 18th mag.

Christopher Ke-shih Young
, PASA, 18 (2), in press.
Next Section: Bright-end consistency checks
Title/Abstract Page: Total Magnitudes of Virgo
Previous Section: Intermediate galaxy sample (14th-12th
Contents Page: Volume 18, Number 2

Bright galaxy sample (14th-8th mag.)

As already mentioned, existing CCD photometry of the brightest Virgo galaxies is generally susceptible to sky-subtraction problems, whilst photographic emulsions are of limited use because of their small dynamic range. One dataset that stands out from existing CCD and photographic ones is the `globally mapped' surface photometry of Caon et al. (1990 & 1994). This photometry couples wide-field photographic images, for which the sky can be determined accurately, with CCD images of the central parts of galaxies that are saturated on most photographic plates. Caon et al. (1990) presented two different sets of total-magnitude estimates: those listed in their Tableá I and those listed in their Tableá VI. Each Tableá I value was obtained by means of an integration to the relevant limiting isophote followed by an

$r^{\frac{1}{4}}$-law extrapolation (based only on the outer few isophotes of each luminosity profile) to an infinite radial distance. Each Tableá VI value on the other hand, was obtained by integration only, but this time to a relatively large radial distance greater than that of the limiting isophote of the published photometry. This latter distance was set as the point at which the surface brightness of the galaxy would fall to $\mu_B = 32$á mag.arcsec-2 if the

$r^{\frac{1}{4}}$-law extrapolation (used to generate its Tableá I value) were an accurate description of the unmeasurable outer parts of the galaxy profile. The total magnitudes presented by Caon et al. (1994) were derived in the same way as Caon et al.'s (1990) Tableá VI values. With a view to generating self-consistent t-system magnitudes independent of any

$r^{\frac{1}{4}}$-law assumption, it was decided to derive new total-magnitude estimates from Caon et al.'s (1990, 1994) original surface-brightness profiles. This was done by integrating the actual light curves numerically between the galaxy centroids r=0 and the faintest isophotes

$r=r_{{\rm max}}$, where r represents azimuthally averaged radial distance. In order to maximise the accuracy of these integrations, the profiles were interpolated in linear-distance-linear-intensity space (rather than

$r^{\frac{1}{4}}$-magnitude space in line with the units listed); and using Hill's (1982) interpolation routine INTEP. Note that the surface-brightness profiles of even the largest giants extended to large enough radial distances so as to include a substantial proportion of any halo light. The profile of NGCá 4406 (=M86) for example, extended out to a radial distance of 10.4á arcmin.

Table 3: Improved total magnitude values (bold type) derived in this paper from a re-analysis of Caon et al.'s (1990 & 1994) surface-brightness profiles; the hitherto undefined quantities $\epsilon $, $\mu _{B_0}$, and r0, being ellipticity, Sö©rsic-model extrapolated central surface brightness and Sö©rsic-model scalelength respectively
Designation VCC type/

$B_{r<r_{{\rm max}}}$

 $r_{{\rm max}}$ $\epsilon $ $\mu _{B_0}$ n r0 Bt(syst.) Bt(integ.) $\Delta B$
á  membership (mag.) (arcsec) (mag.arcesc-2) (arcsec) (mag.) (mag.) (mag.)
1990 data:
ICá 3468 E/M 14.10 57.63 0.24 19.60 0.53 0.1817E+01 13.97 13.97 0.13
ICá 3540 S0/M 14.77 31.18 0.12 19.39 0.72 0.2343E+01 14.64 14.72 0.05
ICá 3653 E/M 14.56 27.06 0.06 18.42 0.64 0.1277E+01 14.53 14.53 0.03
ICá 3773 d:S0/M 14.11 63.50 0.58 18.47 0.45 0.6294E+00 14.03 14.04 0.08
NGCá 4168 E/M 12.34 110.08 0.24 16.09 0.28 0.4401E-01 12.05 12.05 0.29
NGCá 4200 S0/M 14.01 47.25 0.41 17.74 0.42 0.3693E+00 13.90 13.89 0.11
NGCá 4352 S0/M 13.56 68.08 0.38 17.33 0.40 0.3009E+00 13.50 13.49 0.07
NGCá 4374 E/M 10.10 329.17 0.07 9.81 0.15 0.4891E-05 9.69 9.71 0.40
NGCá 4387 E/M 13.16 85.61 0.24 16.24 0.38 0.1708E+00 13.14 13.13 0.03
NGCá 4406 S0/M 9.79 484.53 0.40 11.59 0.15 0.1423E-04 9.15 9.15 0.64
NGCá 4415 d:E/M 13.89 56.30 0.16 19.45 0.54 0.1967E+01 13.76 13.76 0.13
NGCá 4417 S0/M 12.01 125.19 0.30 14.06 0.28 0.1835E-01 11.93 11.95 0.06
NGCá 4431 dS0/M 14.21 43.50 0.33 19.84 0.54 0.2153E+01 13.96 13.96 0.25
NGCá 4434 E-S0/M 13.18 65.63 0.14 14.94 0.30 0.2629E-01 13.06 13.08 0.10
NGCá 4436 dE-dS0/M 14.15 62.06 0.41 18.65 0.42 0.5357E+00 14.00 14.01 0.14
NGCá 4452 S0/M 12.86 95.38 0.60 17.88 0.48 0.1011E+01 12.89 12.83 0.03
NGCá 4458 E/M 13.07 80.72 0.01 15.32 0.29 0.2641E-01 12.94 12.94 0.12
NGCá 4459 S0/M 11.21 197.98 0.19 15.12 0.30 0.6466E-01 11.29 11.15 0.06
NGCá 4464 E/M 13.53 47.53 0.07 15.05 0.36 0.6574E-01 13.46 13.49 0.04
NGCá 4473 E/M 11.15 231.09 0.39 12.34 0.22 0.1525E-02 11.06 11.07 0.08
NGCá 4474 S0/M 12.50 99.85 0.20 15.83 0.33 0.9517E-01 12.43 12.42 0.08
NGCá 4476 S0/M 13.16 90.77 0.15 15.42 0.30 0.3278E-01 13.07 13.09 0.07
NGCá 4478 E/M 12.42 63.42 0.08 16.78 0.50 0.8680E+00 12.39 12.39 0.04
NGCá 4486 E/M 9.71 410.42 0.35 14.43 0.23 0.1314E-01 9.43 9.43 0.27
NGCá 4550 E-S0/M 12.60 71.24 0.68 17.61 0.57 0.1665E+01 12.58 12.57 0.02
NGCá 4551 E/M 13.11 62.71 0.21 17.56 0.50 0.9137E+00 13.07 13.08 0.03
NGCá 4552 S0/M 10.80 245.11 0.17 9.32 0.15 0.2717E-05 10.47 10.48 0.32
NGCá 4564 E/M 12.12 109.83 0.40 14.92 0.32 0.6149E-01 12.07 12.07 0.06
NGCá 4578 S0/M 12.46 108.71 0.25 15.39 0.28 0.2836E-01 12.32 12.31 0.15
NGCá 4621 E/M 10.63 310.37 0.09 9.87 0.15 0.3820E-05 10.29 10.30 0.34
NGCá 4638 S0/M 12.16 82.43 0.38 16.07 0.45 0.5002E+00 12.13 12.14 0.02
NGCá 4660 E-S0/M 12.14 90.29 0.16 12.73 0.26 0.5285E-02 12.06 12.07 0.07
1994 data:
NGCá 4215 S0/M 12.92 54.25 0.61 17.02 0.48 0.6589E+00 12.95 12.88 0.05
NGCá 4255 S0/M 13.69 48.36 0.38 15.92 0.38 0.1180E+00 13.63 13.64 0.04
NGCá 4261 E/M 11.35 171.60 0.25 12.61 0.19 0.3345E-03 10.99 11.00 0.36
NGCá 4268 S0/M 13.74 46.08 0.44 17.58 0.52 0.7694E+00 13.70 13.70 0.03
NGCá 4269 S0/M 13.86 50.93 0.21 9.74 0.15 0.8938E-06 13.31 13.38 0.48
NGCá 4270 S0/M 13.20 60.02 0.45 17.69 0.54 0.1146E+01 13.17 13.17 0.03
NGCá 4339 S0/M 12.56 98.48 0.12 15.82 0.30 0.5332E-01 12.41 12.41 0.15
NGCá 4342 S0/M 13.22 39.99 0.23 11.72 0.26 0.2078E-02 13.08 13.17 0.06
NGCá 4360 E/B 13.69 88.99 0.18 15.88 0.30 0.3175E-01 13.60 13.61 0.07
NGCá 4365 E/M 10.72 210.48 0.32 12.82 0.19 0.5118E-03 10.28 10.28 0.43
NGCá 4377 S0/M 12.79 64.20 0.18 15.32 0.35 0.9057E-01 12.72 12.73 0.07
NGCá 4472 E-S0/M 9.21 622.25 0.15 13.38 0.20 0.2295E-02 8.93 8.93 0.28
NGCá 4570 S0-E/M 11.85 65.71 0.69 15.87 0.42 0.4143E+00 11.77 11.77 0.08
NGCá 4600 S0/M 13.60 64.94 0.16 19.56 0.67 0.3684E+01 13.56 13.56 0.04
NGCá 4623 E/M 13.26 66.19 0.55 18.09 0.47 0.9093E+00 13.18 13.18 0.08
NGCá 4636 E-S0/M 10.31 288.01 0.35 14.59 0.21 0.4698E-02 9.79 9.79 0.52

á  á  á  á  á  á  á  á  á  á 
  • Notes: (1) Membership assignments are based on radial velocities: M (for member) if less than 3500 km ${\rm s}^{-1}$; otherwise B (for background). (2) Bt(syst.) represents systemic total magnitudes derived by integrating the best fitting profile parameters from r=0 to $\infty$. (3) Bt(integ.) represents the sum of

    $B_{r<r_{{\rm max}}}$ and the integral of the best fitting profile parameters from

    $r=r_{{\rm max}}$ to $\infty$. (4)

    $\Delta B = B_{r<r_{{\rm max}}}-B_t$(integ.). (5) For the sake of consistency, NGCá 4215 was not treated differently from the other galaxies when its profile was fitted, even though it probably possesses a ring as noted by Caon et al. (1994). (6) NGCá 4342 is also known as ICá 3256.


We also re-fitted Caon et al.'s light curves with Davies et al.'s (1988) more natural form of Sö©rsic's law, ignoring isophotes flagged as unreliable and/or lacking ellipticity values. This yielded new global profile parameters for each galaxy which were then used for the extrapolation of each profile beyond the limiting isophote to an infinite radial distance. In practice, this involved integrating the best fitting Sö©rsic model from r=0 to $r=\infty$ analytically according to Equationá 7 of Young et al. (1998); and also integrating the same model from r=0 to

$r=r_{{\rm max}}$ numerically using Simpson's rule. The extrapolation term required was therefore the difference between these two values. The improved total magnitude values together with all relevant profile parameters and extrapolation terms are listed in Tableá 3. Note that we omitted NGCá 4649 because Caon et al. (1990) noticed that its isophotes were distorted by the presence of a companion galaxy. Also, in the case of Caon et al.'s (1994) profiles, we only fitted those 16 Virgo objects listed in Tableá (a) of the machine readable version at the CDS.

Next Section: Bright-end consistency checks
Title/Abstract Page: Total Magnitudes of Virgo
Previous Section: Intermediate galaxy sample (14th-12th
Contents Page: Volume 18, Number 2

Welcome... About Electronic PASA... Instructions to Authors
ASA Home Page... CSIRO Publishing PASA
Browse Articles HOME Search Articles
á© Copyright Astronomical Society of Australia 1997
ASKAP
Public