PRE-MAIN-SEQUENCE TURN-ON AS A CHRONOMETER FOR YOUNG CLUSTERS: NGC 346 AS A BENCHMARK

Journal Article · Sat Mar 20 00:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/712/1/L63; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21305081

Cignoni, M ^[1]; Tosi, M ^[2]; Sabbi, E; Nota, A ^[3]; Degl'Innocenti, S; Moroni, P G. Prada ^[4]; Gallagher, J S ^[5]

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1. Dipartimento di Astronomia, Universita degli Studi di Bologna, via Ranzani 1, I-40127 Bologna (Italy)
2. Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)
3. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
4. Dipartimento di Fisica 'Enrico Fermi', Universita di Pisa, largo Pontecorvo 3, Pisa I-56127 (Italy)
5. Department of Astronomy, 475 N. Charter Street, Madison, WI 53706 (United States)

We present a novel approach to deriving the age of very young star clusters, by using the Turn-On (TOn). The TOn is the point in the color-magnitude diagram (CMD) where the pre-main sequence (PMS) joins the main sequence (MS). In the MS luminosity function (LF) of the cluster, the TOn is identified as a peak followed by a dip. We propose that by combining the CMD analysis with the monitoring of the spatial distribution of MS stars it is possible to reliably identify the TOn in extragalactic star-forming regions. Compared to alternative methods, this technique is complementary to the turnoff dating and avoids the systematic biases affecting the PMS phase. We describe the method and its uncertainties and apply it to the star-forming region NGC 346, which has been extensively imaged with the Hubble Space Telescope (HST). This study extends the LF approach in crowded extragalactic regions and opens the way for future studies with HST/WFC3, the James Webb Space Telescope and from the ground with adaptive optics.

• OSTI ID: 21305081
• Journal Information: Astrophysical Journal Letters, Vol. 712, Issue 1; Other Information: DOI: 10.1088/2041-8205/712/1/L63; Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
AGE ESTIMATION
COLOR
GALACTIC EVOLUTION
LUMINOSITY
MAGELLANIC CLOUDS
SPATIAL DISTRIBUTION
STAR CLUSTERS
STARS
TELESCOPES