2020A&A...637A...8J


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.25CET09:43:19

2020A&A...637A...8J - Astronomy and Astrophysics, volume 637A, 8-8 (2020/5-1)

Tracing the anemic stellar halo of M 101.

JANG I.S., DE JONG R.S., HOLWERDA B.W., MONACHESI A., BELL E.F. and BAILIN J.

Abstract (from CDS):

Models of galaxy formation in a cosmological context predict that massive disk galaxies should have structured extended stellar halos. Recent studies in integrated light, however, report that a few galaxies, including the nearby disk galaxy M 101, have no measurable stellar halos to the detection limit. We aim to quantify the stellar content and structure of M 101's outskirts by resolving its stars. We present the photometry of its stars based on deep F606W and F814W images taken with Hubble Space Telescope (HST) as part of the GHOSTS survey. The HST fields are placed along the east and west sides of M 101 out to galactocentric distance (R) of ∼70kpc. The constructed color-magnitude diagrams of stars reach down to two magnitudes below the tip of the red giant branch. We derived radial number density profiles of the bright red giant branch (RGB) stars. The mean color of the RGB stars at R∼40-60kpc is similar to those of metal-poor globular clusters in the Milky Way. We also derived radial surface brightness profiles using the public image data provided by the Dragonfly team. Both the radial number density and surface brightness profiles were converted to radial mass density profiles and combined. We find that the mass density profiles show a weak upturn at the very outer region, where surface brightness is as faint as µg~=33mag/arcsec2. An exponential disk + power-law halo model on the mass density profiles finds the total stellar halo mass of Mhalo=8.2–2.2+3.5x107M. The total stellar halo mass does not exceed Mhalo=3.2x108M when strongly truncated disk models are considered. In combining the halo mass with the total stellar mass of M 101, we obtain the stellar halo mass fraction of Mhalo/Mgal=0.20–0.08+0.10% with an upper limit of 0.78%. We compare the halo properties of M 101 with those of six GHOSTS survey galaxies as well as the Milky Way and M 31 and find that M 101 has an anemic stellar halo similar to the Milky Way.

Abstract Copyright: © ESO 2020

Journal keyword(s): stars: Population II - Galaxy: halo - galaxies: spiral - galaxies: structure - galaxies: individual: M 101

Simbad objects: 14

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Number of rows : 14

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 55 GiG 00 14 53.602 -39 11 47.86 8.54 8.58 7.87 7.84   ~ 712 2
2 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3583 0
3 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11090 1
4 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 2970 2
5 NGC 891 H2G 02 22 32.907 +42 20 53.95 11.08 10.81 9.93 7.86   ~ 1539 2
6 NGC 1042 GiP 02 40 23.9725496856 -08 26 00.749394900 11.47 11.56 11.02 11.7 11.4 ~ 227 1
7 NGC 2403 AGN 07 36 51.396 +65 36 09.17 9.31 8.84 8.38 8.19   ~ 1629 1
8 NGC 2419 GlC 07 38 08.51 +38 52 54.9     10.05     ~ 823 0
9 M 81 Sy2 09 55 33.17306143 +69 03 55.0609270   7.89 6.94     ~ 4009 5
10 M 95 GiP 10 43 57.733 +11 42 13.00 10.71 10.51 9.73 9.48   ~ 953 2
11 NGC 4631 GiP 12 42 08.009 +32 32 29.44   9.78 9.19 9.10   ~ 982 2
12 NAME Centaurus A Sy2 13 25 27.61509104 -43 01 08.8056025   8.18 6.84 6.66   ~ 4039 3
13 M 101 GiP 14 03 12.583 +54 20 55.50   8.46 7.86 7.76   ~ 2579 2
14 NAME Local Group GrG ~ ~           ~ 7108 0

    Equat.    Gal    SGal    Ecl

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2020.11.25-09:43:19

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