GeMS in the Outer Galaxy: Near-infrared Imaging of Three Young Clusters at Large Galactic Radii

Images recorded with the Gemini South Adaptive Optics Imager (GSAOI) and corrected for atmospheric seeing by the Gemini Multi-conjugate Adaptive Optics System are used to investigate the stellar contents of the young outer Galactic disk clusters Haffner 17, NGC 2401, and NGC 3105. Ages estimated from the faint end of the main sequence (MS) and the ridgeline of the pre-main sequence on the (K, J – K) color-magnitude diagrams are consistent with published values that are based on the MS turnoff, with the GSAOI data favoring the younger end of the age range for NGC 2401 in the literature. The mass function (MF) of NGC 2401 is similar to that in the solar neighborhood, and stars spanning a wide range of masses in this cluster have similar clustering properties on the sky. It is concluded that NGC 2401 is not evolved dynamically. In contrast, the MF of Haffner 17 differs significantly from that in the solar neighborhood over all masses covered by these data, while the MF of NGC 3105 is deficient in objects with sub-solar masses when compared with the solar neighborhood. Low-mass objects in Haffner 17 and NGC 3105 are also more uniformly distributed on the sky than brighter, more massive, MS stars. This is consistent with both clusters having experienced significant dynamical evolution.

[1]  S. E. Persson,et al.  A New System of Faint Near-Infrared Standard Stars , 1998 .

[2]  Eleazar R. Carrasco,et al.  Science readiness of the Gemini MCAO System: GeMS , 2012, Other Conferences.

[3]  T. Henning,et al.  INSTANTANEOUS STARBURST OF THE MASSIVE CLUSTERS WESTERLUND 1 AND NGC 3603 YC , 2012, 1204.5481.

[4]  S. Larsen,et al.  The star cluster – field star connection in nearby spiral galaxies - II. Field star and cluster formation histories and their relation , 2011, 1101.4021.

[5]  C. Lada,et al.  Embedded Clusters in Molecular Clouds , 2003, astro-ph/0301540.

[6]  T. Davidge.  AND THE REST: THE STELLAR ARCHEOLOGICAL RECORD OF M82 OUTSIDE THE CENTRAL STARBURST , 2008, 0810.0843.

[7]  S. M. Fall,et al.  SIMILARITIES IN POPULATIONS OF STAR CLUSTERS , 2012, 1206.4237.

[8]  K. D. Keele,et al.  FROM DARKNESS TO LIGHT , 1959 .

[9]  D. Balser,et al.  H ii REGION METALLICITY DISTRIBUTION IN THE MILKY WAY DISK , 2011, 1106.1660.

[10]  A. Robin,et al.  A synthetic view on structure and evolution of the Milky Way , 2003 .

[11]  Constraining the star formation rate in the solar neighbourhood with star clusters , 2011, 1104.2182.

[12]  Peter B. Stetson,et al.  CCD photometry of the globular cluster M92 , 1988 .

[13]  Gabe Bloxham,et al.  Gemini South Adaptive Optics Imager (GSAOI) , 2004, SPIE Astronomical Telescopes + Instrumentation.

[14]  Bonn,et al.  The dynamical state of stellar structure in star‐forming regions , 2011, 1109.0986.

[15]  T. Davidge.  THE YOUNG OPEN CLUSTERS KING 12, NGC 7788, AND NGC 7790: PRE-MAIN-SEQUENCE STARS AND EXTENDED STELLAR HALOS , 2012, 1211.6398.

[16]  S. Brittain,et al.  MEASURING THE STELLAR ACCRETION RATES OF HERBIG Ae/Be STARS , 2011 .

[17]  D. Schlegel,et al.  Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds , 1998 .

[18]  D. Fried.  Optical Resolution Through a Randomly Inhomogeneous Medium for Very Long and Very Short Exposures , 1966 .

[19]  P. Stetson.  DAOPHOT: A COMPUTER PROGRAM FOR CROWDED-FIELD STELLAR PHOTOMETRY , 1987 .

[20]  R. Larson.  Star formation in groups , 1995 .

[21]  Heidelberg,et al.  AGE SPREAD IN W3 MAIN: LARGE BINOCULAR TELESCOPE/LUCI NEAR-INFRARED SPECTROSCOPY OF THE MASSIVE STELLAR CONTENT , 2011, 1109.3467.

[22]  Daniel Egret,et al.  Information & on-line data in astronomy , 1995 .

[23]  N. Panagia,et al.  PHOTOMETRIC DETERMINATION OF THE MASS ACCRETION RATES OF PRE-MAIN-SEQUENCE STARS. II. NGC 346 IN THE SMALL MAGELLANIC CLOUD , 2011, 1104.4494.

[24]  A. Nota,et al.  PRE-MAIN-SEQUENCE TURN-ON AS A CHRONOMETER FOR YOUNG CLUSTERS: NGC 346 AS A BENCHMARK , 2010, 1001.4442.

[25]  T. Sakamoto,et al.  New Photometric Data of Old Open Clusters II. A Dataset for 36 Clusters , 2008 .

[26]  D. Schlegel,et al.  Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds , 1997, astro-ph/9710327.

[27]  U. Gorti,et al.  Photoevaporation of Circumstellar Disks Due to External Far-Ultraviolet Radiation in Stellar Aggregates , 2004, astro-ph/0404383.

[28]  T. Davidge.  The Disk and Extraplanar Regions of NGC 2403 , 2007, 0706.3464.

[29]  J. Bally,et al.  Photoevaporation of Disks and Clumps by Nearby Massive Stars: Application to Disk Destruction in the Orion Nebula , 1998 .

[30]  Christopher Portier,et al.  Risk factors for childhood leukaemia. Discussion and summary. , 2008, Radiation protection dosimetry.

[31]  G. Carraro,et al.  NGC 2401: A template of the young population of the Norma-Cygnus arm in the Third Galactic Quadrant , 2006 .

[32]  G. Chabrier.  The Galactic Disk Mass Budget. I. Stellar Mass Function and Density , 2001 .

[33]  M. Krumholz,et al.  ON THE RELIABILITY OF STELLAR AGES AND AGE SPREADS INFERRED FROM PRE-MAIN-SEQUENCE EVOLUTIONARY MODELS , 2011, 1101.3599.

[34]  Rory J. E. Smith,et al.  Surviving infant mortality in the hierarchical merging scenario , 2011, 1102.5360.

[35]  R. Sagar,et al.  A multicolour CCD photometric and mass function study of the distant southern open star clusters NGC 3105, NGC 3603, Melotte 105, Hogg 15, NGC 4815, Pismis 20 and NGC 6253 , 2001 .

[36]  F. I. Pelupessy,et al.  The evolution of embedded star clusters , 2011, 1111.0992.

[37]  P. Kroupa,et al.  Inverse dynamical population synthesis: Constraining the initial conditions of young stellar clusters by studying their binary populations , 2012, 1205.1508.

[38]  P. Kroupa,et al.  A comprehensive set of simulations studying the influence of gas expulsion on star cluster evolution , 2007, 0707.1944.

[39]  P. Kroupa,et al.  Dynamical population synthesis: constructing the stellar single and binary contents of galactic field populations , 2011, 1109.2896.

[40]  Peter Pessev,et al.  GeMS: first on-sky results , 2012, Other Conferences.

[41]  Moscow,et al.  The early expansion of cluster cores , 2008, 0806.1460.

[42]  F. Rigaut,et al.  Haffner 16: A Young Moving Group in the Making , 2013, 1308.5432.

[43]  J. Moustakas,et al.  STAR CLUSTER POPULATIONS IN THE OUTER DISKS OF NEARBY GALAXIES , 2012, 1205.5072.

[44]  A. J. Delgado,et al.  Physical parameters of pre-main sequence stars in open clusters , 2011, 1105.5906.