Kinematically cold and warm planetary nebulae samples, HII regions and supernovae remnants in the disc of the face-on spiral galaxy NGC 628 (M74) -- The Planetary Nebulae Spectrograph with the H$α$ arm
Abstract
We present the results for the galaxy NGC 628 observed with the Planetary Nebulae Spectrograph (PN.S) equipped with the H$α$ arm. With the third PN.S arm, the H$α$ arm, we measure the H$α$ fluxes, in addition to fluxes and line-of-sight velocities (LOSV) of monochromatic spatially unresolved [OIII] 5007Å sources. The narrow band color ([OIII] 5007Å-H$α$) vs m5007 magnitude diagram separates planetary nebulae (PNe) from single compact ionized HII regions and supernovae remnants (SNRs), which also emit in [OIII]5007 Å. The goals are to detect bona-fide PNe in the face-on spiral galaxy NGC 628 (M74) so that we can measure the velocity dispersion of the stars perpendicular to the main plane of the disc. This study validates the empirical selection criteria for PNe with the PN.S in star forming discs. We classified 442 PNe and 251 spatially isolated, unresolved HII regions: the PN.S with the H$α$ arm increased the number of known PNe by a factor 4. We find evidence for two kinematically distinct PN populations in the NGC 628 disc. The kinematically cold PN population dominates the PN luminosity function close to the bright cut-off magnitude, indicating that the PN massive, short-lived progenitors dominate the PNLF bright cut-off in NGC 628. The warmer PN component increasingly dominates at fainter magnitudes. The velocity dispersion orthogonal to the disc plane are σz,cold = 8.8 kms-1 and σz,warm =26.1 kms-1 respectively, over a range of radii 80 to 425 arcsec. These components contribute with the ratio 46% (cold) and 54% (warm). Once the velocity dispersion of the old component is matched with the population's scale height, the decomposition of the rotation curve for NGC 628 leads to a maximal disc, with the rotation of the baryonic component accounting for 78% of the total rotational velocity in NGC 628.
Authors 17
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Affiliation as printed
ESO , Karl Schwarzschild Str. 2 , D-85748 Germany
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Max Planck Institute for Extraterrestrial Physics
Affiliation as printed
Max-Planck-Institüt fur Extraterrestrisches Physik , Giessenbach Str. , D-85741 Garching , Germany
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Australian National University
Affiliation as printed
Research School of Astronomy and Astrophysics , Australia National University , Canberra ACT 2611 , Australia
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Australian National University
Affiliation as printed
Research School of Astronomy and Astrophysics , Australia National University , Canberra ACT 2611 , Australia
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Australian National University · University of Oxford
Affiliation as printed
Oxford Astrophysics , University of Oxford , Denys Wilkinson Building , Keble Rd , Oxford OX1 3RH , UK
Research School of Astronomy and Astrophysics , Australia National University , Canberra ACT 2611 , Australia
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Affiliation as printed
ESO , Karl Schwarzschild Str. 2 , D-85748 Germany
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Affiliation as printed
School of Physics and Astronomy , University of Nottingham , Nottingham , NG7 2RD , UK
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Universidade Federal do Rio de Janeiro · Valongo Observatory
Affiliation as printed
Universidade Federal do Rio de Janeiro , Observatório do Valongo , CEP 20080-090 Rio de Janeiro , RJ , Brazil
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Affiliation as printed
Medicine and Technology (TCSMT) , University of Turku , FI-20014 Turku , Finland;
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Astronomical Observatory of Capodimonte · National Institute for Astrophysics
Affiliation as printed
Osservatorio Astronomico di Capodimonte , INAF , Salita Moiariello 16 , I-80131 , Italy
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Affiliation as printed
School of Physics and Astronomy , University of Nottingham , Nottingham , NG7 2RD , UK
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Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory , Leiden University , the Netherlands
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University of Naples Federico II
Affiliation as printed
Department of Physics "E. Pancini" , University of Naples Federico II , Via Cintia, 21 , 80126 Naples , Italy
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University of Naples Federico II
Affiliation as printed
Department of Physics "E. Pancini" , University of Naples Federico II , Via Cintia, 21 , 80126 Naples , Italy
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Max Planck Institute for Extraterrestrial Physics
Affiliation as printed
Max-Planck-Institüt fur Extraterrestrisches Physik , Giessenbach Str. , D-85741 Garching , Germany
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Affiliation as printed
Department of Physics and Astronomy , San Jose State University , One Washington Square , San Jose , CA 95192 , USA