J/AJ/157/22 Luminous and variable stars in NGC 2403 and M81 (Humphreys+, 2019)
Luminous and variable stars in NGC 2403 and M81.
Humphreys R.M., Stangl S., Gordon M.S., Davidson K., Grammer S.H.
<Astron. J., 157, 22 (2019)>
=2019AJ....157...22H 2019AJ....157...22H (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, luminous ; Stars, variable ;
Stars, supergiant ; Spectral types ; Photometry, UBVRI ;
Photometry, HST ; Photometry, infrared ; Reddening ; Extinction
Keywords: galaxies: individual (NGC 2403, M81) - supergiants
Abstract:
We present the results of spectroscopy and multi-wavelength photometry
of luminous and variable star candidates in the nearby spiral galaxies
NGC 2403 and M81. We discuss specific classes of stars, the Luminous Blue
Variables (LBVs), B[e] supergiants (sgB[e]), and the high-luminosity
yellow hypergiants. We identify two new LBV candidates, and three sgB[e]
stars in M81. We also find that some stars that were previously considered
LBV candidates are actually field stars. The confirmed and candidate LBVs
and sgB[e] stars together with the other confirmed members are shown on
the HR Diagrams for their respective galaxies. We also present the
HR Diagrams for the two "SN impostors", V37 (SN2002kg) and V12 (SN1954J)
in NGC 2403 and the stars in their immediate environments.
Description:
Most of our targets were selected from the Zickgraf & Humphreys
(1991AJ....102..113Z 1991AJ....102..113Z) catalogs for NGC 2403 and M81 based on their apparent
magnitude and color. We emphasized those most likely to be luminous
early-type stars and suspected variables. To select additional candidates,
we used aperture photometry measured from the Hubble Legacy Archive (HLA)
Advanced Camera for Survey (ACS) images of NGC 2403 and M81 in the ANGRRR
and ANGST programs (Proposals GO-10182, GO-10579, and GO-10584). Following
these criteria, we selected 124 stars in NGC 2403 with V magnitudes between
18.0 and 20.1, and 91 in M81 with V magnitudes between 18.5 and 20.1.
Eighty-six in NGC 2403 were assigned fibers in two separate pointings,
fields F1 and F2, and 61 stars in M81 were assigned fibers.
The spectra were observed with the Hectospec, a multi-object spectrometer
mounted on the MMT (Fabricant et al. 1998SPIE.3355..285F 1998SPIE.3355..285F,
2005PASP..117.1411F 2005PASP..117.1411F). The Hectospec is a fiber-fed MOS with a 1° FOV
and 300 fibers; each fiber subtends 1.5" on the sky. We used the 600 mm-1
grating with the blue tilt centered on 4800 Å and the red tilt centered
on 7300 Å. The red tilt was chosen to include Hα plus the Ca II
triplet at ∼8500 Å. The 600 mm-1 grating gives a spectral coverage
of ∼2500 Å with 0.54 Å/pixel resolution. The NGC 2403 targets were
observed in 2012 October and December in two fields, F1 and F2. The total
exposures times in the blue were 4H and 4H 15M for F1 and F2, respectively,
and for the red spectra, 3H for F1 and 2.5H for F2. Unfortunately, the M81
observations were plagued by poor observing conditions. Consequently, the
spectra were acquired over two observing seasons in 2012 and again in 2014.
Objects:
--------------------------------------------------------
RA (ICRS) DE Designation(s)
--------------------------------------------------------
07 36 51.40 +65 36 09.2 NGC 2403 = IRAS 07321+6543
09 55 33.17 +69 03 55.1 M81 = IRAS 09514+6918
--------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 207 40 Members of NGC 2403
table3.dat 207 28 Members of M81
table5.dat 185 51 Multi-wavelength photometry
table6.dat 105 48 Interstellar extinction and luminosities
table7.dat 207 77 Foreground stars and others
--------------------------------------------------------------------------------
See also:
J/ApJ/438/181 : Observations of H II Regions in M81 (Hill+ 1995)
J/AJ/122/1330 : HST BVI photometry of M 81 star clusters (Chandar+, 2001)
J/AJ/126/1286 : Hα+[NII] observations of M81 HII regions (Lin+, 2003)
J/ApJ/648/987 : UV through far-IR analysis of M81 (Perez-Gonzalez+, 2006)
J/A+A/521/A3 : Abundances in HII regions and PNe of M81
(Stanghellini+, 2010)
J/AJ/139/1413 : M81 star cluster candidates (Nantais+, 2010)
J/MNRAS/405/1293 : Compact star clusters in M81 (Santiago-Cortes+, 2010)
J/ApJ/743/176 : BVI photometry of Cepheids in M81 (Gerke+, 2011)
J/A+A/567/A88 : Abundances in HII regions of M81 (Stanghellini+, 2014)
J/ApJ/853/151 : Oxygen abundances for giant HII regions in NGC 2403
(Mao+, 2018)
Byte-by-byte Description of file: table2.dat table3.dat table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Gal Galaxy host (NGC 2403 or M81)
10- 20 A11 --- Star Stellar identifier
22- 26 A5 --- Field Field designation (not in Table 3) (1)
28- 41 A14 --- OName Other stellar identifier(s)
43 I1 h RAh Hour of Right Ascension (J2000)
45- 46 I2 min RAm Minute of Right Ascension (J2000)
48- 54 F7.4 s RAs Second of Right Ascension (J2000)
55 A1 --- DE- Sign of the Declination (J2000)
56- 57 I2 deg DEd Degree of Declination (J2000)
59- 60 I2 arcmin DEm Arcminute of Declination (J2000)
62- 66 F5.2 arcsec DEs Arcsecond of Declination (J2000)
68- 85 A18 --- SpType Spectral type
86 A1 --- n_SpType [b] Note on SpType (only in Table 3) (2)
88- 92 F5.2 mag Vmag [17.49/20.69]? Visual magnitude
94-100 A7 --- Source Primary source(s) for target (3)
102-105 A4 --- Var Variability?
107-187 A81 --- Com Comment on the spectrum and observation
189-207 A19 --- Bibcode Bibcode of reference in Com (not in Table 3)
--------------------------------------------------------------------------------
Note (1): "F1" was centered at 07:36:25.89 +65:38:48.4 and "F2" was centered
at 07:36:23.19 +65:34:54.2.
Note (2): Note as follows:
b = Candidate Luminous Blue Variable (LBV).
Note (3): Source as follows:
1 = Zickgraf & Humphreys (1991AJ....102..113Z 1991AJ....102..113Z);
2 = GO-10182;
3 = GO-10579;
4 = Tammann & Sandage (1968ApJ...151..825T 1968ApJ...151..825T);
5 = Sandage (1984AJ.....89..621S 1984AJ.....89..621S);
6 = GO-10584;
7 = Sandage (1984AJ.....89..630S 1984AJ.....89..630S).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Gal Galaxy host (NGC 2403 or M81)
10- 20 A11 --- Star Stellar identifier
22- 35 A14 --- OName Other stellar identifier(s)
36 A1 --- f_Star [c] Flag on Star (1)
38- 42 F5.2 mag Umag [16.6/22.15]? U band magnitude (2)
43 A1 --- u_Umag [:] Uncertainty flag on Umag
45- 49 F5.2 mag Bmag [18.01/21.62]? B band magnitude (2)
51- 55 F5.2 mag Vmag [17.49/20.35]? V band magnitude (2)
57- 61 F5.2 mag Rmag [18/20.23]? R band magnitude (2)
63- 67 F5.2 mag F435mag [19.49/21.19]? HST/ACS F435W filter magnitude
(3)
69- 73 F5.2 mag F475mag [19.23/20.52]? HST/ACS F475W filter magnitude
(3)
75- 79 F5.2 mag F606mag [18.87/20.08]? HST/ACS F606W filter magnitude
(3)
81- 85 F5.2 mag 1.1mag [17.25/21.1]? HST/WFC3 1.1 um filter magnitude
87- 91 F5.2 mag 1.6mag [16.78/19.24]? HST/WFC3 1.6 um filter magnitude
93- 95 I3 uJy F3.6 [3/614]? Spitzer/IRAC 3.6 micron band flux
density
97-101 F5.1 uJy F4.5 [1.6/411]? Spitzer/IRAC 4.5 micron band flux
density
103-106 I4 uJy F5.8 [15/1205]? Spitzer/IRAC 5.8 micron band flux
density
107-108 A2 --- f_F5.8 [f :] Flag on F5.8 (4)
110-112 I3 uJy F8.0 [129/282]? Spitzer/IRAC 8.0 micron band flux
density
113 A1 --- f_F8.0 [f:] Flag on F8.0 (4)
115-165 A51 --- Com Additional comments
167-185 A19 --- Bibcode Bibcode of reference in Com
--------------------------------------------------------------------------------
Note (1): Flag as follows:
c = Photographic UBVR magnitudes from Zickgraf and Humphreys
(1991AJ....102..113Z 1991AJ....102..113Z).
Note (2): LBT/LBC magnitude unless designated otherwise as a footnote to the
star ID or in comments.
Note (3): Magnitude from HST images, see text.
Note (4): Flag as follows:
: = Uncertain;
:: = Highly uncertain;
f = Fuzzy.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Gal Galaxy host (NGC 2403 or M81)
10- 20 A11 --- Star Stellar identifier
22- 35 A14 --- OName Other stellar identifier(s)
36 A1 --- n_Star [c] Note on Star (1)
38- 45 A8 --- SpType Spectral type
47- 51 F5.2 mag B-V1 [-0.21/1.36]? LBC B-V color index
52 A1 --- u_B-V1 [:] Uncertainty flag on B-V1
54- 57 F4.2 mag B-V2 [0.08/1.58]? HST B-V color index
58 A1 --- u_B-V2 [:] Uncertainty flag on B-V2
60- 63 F4.2 mag b_E(B-V) [0/1]? Reddening, lower value
64 A1 --- ubE(B-V) [:?] Uncertainty flag on b_E(B-V)
66- 69 F4.2 mag B_E(B-V) [0.29/0.8]? Reddening, upper value
71- 74 F4.2 mag b_Av [0.16/3.2]? Visual extinction, lower value
75 A1 --- ubAv [)] Uncertainty flag on b_Av
77- 80 F4.2 mag B_Av [0.9/1.06]? Visual extinction, upper value
82- 87 F6.2 mag VMag [-11.7/-7.7]? Absolute visual magnitude
88 A1 --- u_VMag [:] Uncertainty flag on VMag
89 A1 --- n_VMag [b] Note on VMag (2)
91- 96 F6.2 mag Mbol [-11.6/-7.8]? Bolometric magnitude
97 A1 --- u_Mbol [:] Uncertainty flag on Mbol
99-103 I5 K Temp [5500/21700]? Temperature
104 A1 --- u_Temp [:] Uncertainty flag on Temp
105 A1 --- f_Temp [*] Flag on Temp (3)
--------------------------------------------------------------------------------
Note (1): Note as follows:
c = Note exceptionally high luminosity. Its HST image in Figure B1 shows it is
extended.
Note (2): Note as follows:
b = MV depends on the adopted visual magnitude: -9.45(LBC), -8.06(HST).
Note (3): Flag as follows:
* = Temperature based on the Planck fit to the SED.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 06-May-2019