J/AJ/147/16 Spectroscopy of planetary nebulae in M31 (Kniazev+, 2014)
A search for planetary nebulae with the Sloan Digital Sky Survey: the outer
regions of M31.
Kniazev A.Y., Grebel E.K., Zucker D.B., Rix H.-W., Martinez-Delgado D.,
Snedden S.A.
<Astron. J., 147, 16 (2014)>
=2014AJ....147...16K 2014AJ....147...16K
ADC_Keywords: Galaxies, nearby ; Photometry, ugriz ; Spectroscopy ;
Planetary nebulae ; Radial velocities
Keywords: galaxies: abundances - galaxies: evolution -
galaxies: individual: M31 - galaxies: structure - Local Group
Abstract:
We have developed a method to identify planetary nebula (PN)
candidates in imaging data of the Sloan Digital Sky Survey (SDSS).
This method exploits the SDSS's five-band sampling of emission lines
in PN spectra, which results in a color signature distinct from that
of other sources. Selection criteria based on this signature can be
applied to nearby galaxies in which PNe appear as point sources. We
applied these criteria to the whole area of M31 as scanned by the
SDSS, selecting 167 PN candidates that are located in the outer
regions of M31. The spectra of 80 selected candidates were then
observed with the 2.2m telescope at Calar Alto Observatory. These
observations and cross-checks with literature data show that our
method has a selection rate efficiency of about 90%, but the
efficiency is different for the different groups of PN candidates. In
the outer regions of M31, PNe trace different well-known morphological
features like the Northern Spur, the NGC 205 Loop, the G1 Clump, etc.
In general, the distribution of PNe in the outer region 8<R<20kpc
along the minor axis shows the "extended disk"-a rotationally
supported low surface brightness structure with an exponential scale
length of 3.21±0.14kpc and a total mass of ∼1010M☉, which is
equivalent to the mass of M33. We report the discovery of three PN
candidates with projected locations in the center of Andromeda NE, a
very low surface brightness giant stellar structure in the outer halo
of M31. Two of the PNe were spectroscopically confirmed as genuine
PNe. These two PNe are located at projected distances along the major
axis of ∼48Kpc and ∼41Kpc from the center of M31 and are the most
distant PNe in M31 found up to now. With the new PN data at hand we
see the obvious kinematic connection between the continuation of the
Giant Stream and the Northern Spur. We suggest that 20%-30% of the
stars in the Northern Spur area may belong to the Giant Stream. In our
data we also see a possible kinematic connection between the Giant
Stream and PNe in Andromeda NE, suggesting that Andromeda NE could be
the core or remnant of the Giant Stream. Using PN data we estimate the
total mass of the Giant Stream progenitor to be ~109M☉.
About 90% of its stars appear to have been lost during the interaction
with M31.
Description:
Spectroscopic follow-up observations of a subset of our PN candidates
in M31 were carried out in 2004 October 7-14 at Calar Alto Observatory
with the Calar Alto Faint Object Spectrograph at the 2.2m telescope.
The detector was a SITE 2K*2K CCD. The resulting wavelength coverage
was λ4200-λ6800. The obtained dispersion was
∼1.9-2Å/pixel, leading to a spectral resolution of ∼4-6Å (FWHM).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 125 167 SDSS positions and magnitudes of selected planetary
nebulae (PN) candidates in SDSS M31 data
table2.dat 51 70 Heliocentric velocities and observed line fluxes of
our confirmed planetary nebulae (PNe) in M31
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See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
J/AJ/134/2474 : Ha emission-line stars in 7 dwarfs galaxies (Massey+, 2007)
J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)
J/MNRAS/369/97 : M31 planetary nebula velocities (Halliday+, 2006)
J/MNRAS/369/120 : Kinematic survey of planetary nebulae in M31 (Merrett+, 2006)
J/ApJ/616/804 : Planetary Nebula Kinematics in M31 (Hurley-Keller+, 2004)
J/ApJS/38/351 : M31 planetary nebulae (Ford+, 1978)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/167] Running sequence number
5- 18 A14 --- SDSS SDSS name (JHHMMSS+DDMMSS)
20- 21 I2 h RAh Hour of Right Ascension (J2000)
23- 24 I2 min RAm Minute of Right Ascension (J2000)
26- 30 F5.2 s RAs Second of Right Ascension (J2000)
32 A1 --- DE- Sign of the Declination (J2000)
33- 34 I2 deg DEd Degree of Declination (J2000)
36- 37 I2 arcmin DEm Arcminute of Declination (J2000)
39- 43 F5.2 arcsec DEs Arcsecond of Declination (J2000)
45- 49 F5.2 mag umag SDSS u-band magnitude (1)
51- 54 F4.2 mag e_umag Uncertainty in umag
56- 60 F5.2 mag gmag SDSS g-band magnitude (1)
62- 65 F4.2 mag e_gmag Uncertainty in gmag
67- 71 F5.2 mag rmag SDSS r-band magnitude (1)
73- 76 F4.2 mag e_rmag Uncertainty in rmag
78- 82 F5.2 mag imag SDSS i-band magnitude (1)
84- 87 F4.2 mag e_imag Uncertainty in imag
89- 93 F5.2 mag zmag SDSS z-band magnitude (1)
95- 98 F4.2 mag e_zmag Uncertainty in zmag
100 I1 --- T [1/2] Priority: 1=first, 2=second.
102 I1 --- Obs [0/4] Result of our spectroscopic observations
(1=confirmed planetary nebula) (2)
104-109 A6 --- Host Possible association of objects from our sample
with some structures of the outer region of
M31 (3)
111-125 A15 --- OCat Cross-identifications with other catalogs of
planetary nebulae in M31 (4)
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Note (1): PSF magnitudes corrected for the extinction.
Note (2): and visual checks with data from the "Survey of Local Group Galaxies
Currently Forming Stars" (SLGG; Massey et al., 2006, cat. J/AJ/131/2478;
2007, cat. J/AJ/134/2474). See Section 3.1 for detailed explanations.
Our spectroscopic results are:
0 = Not observed;
1 = Confirmed PN;
2 = Not detected in our follow-up, but identified later via
cross-identifications with other catalogs;
3 = Not detected in our follow-up;
4 = Our unobserved candidates with obvious emission in [OIII] λ5007 and
Hα narrow filters from SLGG data.
Note (3): Structures of the outer region of M31 are defined as follows:
NGC205 = in NGC 205;
SW = SW Shell;
G1 = G1 Clump;
GL = G1 Clump loop;
LO = NGC 205 Loop;
SP = Northern Spur;
GS = Giant Stream;
NS = NE Shelf;
NE = Andromeda NE.
Note (4): Codes for the catalogs are defined as follows:
JF86 = Jacoby & Ford (1986ApJ...304..490J 1986ApJ...304..490J);
NF87 = Nolthenius & Ford (1987ApJ...317...62N 1987ApJ...317...62N);
HK04 = Hurley-Keller et al. (2004, cat. J/ApJ/616/804);
M06 = Merrett et al. (2006, cat. J/MNRAS/369/120).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/70] Running sequence number
4- 17 A14 --- SDSS SDSS name (JHHMMSS+DDMMSS)
19- 22 I4 km/s HRV Heliocentric radial velocity
24- 25 I2 km/s e_HRV ? Uncertainty in HRV
27- 30 F4.1 10-19W/m2 FHb ? Observed Hβ line flux (1)
32- 36 F5.1 10-19W/m2 F5007 Observed [OIII]λ5007 line flux (1)
38- 41 F4.1 10-19W/m2 FHa Observed Hα line flux (1)
43- 46 F4.1 10-19W/m2 F6584 ? Observed [NII]λ6584 line flux (1)
48- 51 F4.2 --- CHb ? Derived extinction coefficient C(Hβ) (2)
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Note (1): In 10-16erg/s/cm2.
Note (2): Based on the Hα/Hβ ratio.
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History:
From electronic version of the journal
(End) Sylvain Guehenneux [CDS] 28-Aug-2014