The Stellar Population of the Chamaeleon I Star-forming Region

By K. Luhman. 2007

218 citations recorded by the source corpus.

I present a new census of the stellar population in the Chamaeleon I star-forming region. Using optical and near-IR photometry and follow-up spectroscopy, I have discovered 50 new members of Chamaeleon I, expanding the census of known members to 226 objects. Fourteen of these new members have spectral types later than M6, which doubles the number of known members that are likely to be substellar. I have estimated extinctions, luminosities, and effective temperatures for the known members, used these data to construct an H-R diagram for the cluster, and inferred individual masses and ages with the theoretical evolutionary models of Baraffe and Chabrier. The distribution of isochronal ages indicates that star formation began 3-4 and 5-6 Myr ago in the southern and northern subclusters, respectively, and has continued to the present time at a declining rate. The IMF in Chamaeleon I reaches a maximum at a mass of 0.1-0.15 M☉ and thus closely resembles the IMFs in IC 348 and the Orion Nebula Cluster. In logarithmic units where the Salpeter slope is 1.35, the IMF is roughly flat in the substellar regime and shows no indication of reaching a minimum down to a completeness limit of 0.01 M☉. The low-mass stars are more widely distributed than members at other masses in the northern subcluster, but this is not the case in the southern subcluster. Meanwhile, the brown dwarfs have the same spatial distribution as the stars out to a radius of 3° (8.5 pc) from the center of Chamaeleon I.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

X-Shooter study of accretion in Chamaeleon I (2015, methodology): “The sample of pre-main sequence (PMS) stars presented in this study was selected from Luhman (2004, 2007), Spezzi et al. (2008), and Alcalá et al. (2008) and has been observed with X-Shooter (Vernet et al. 2011) on the Very Large Telescope (Paranal, Chile) between January 17 and 19, 2010.”
A STEEPER THAN LINEAR DISK MASS–STELLAR MASS SCALING RELATION (2016, methodology): “We note that our ALMA sample has a median age of 3.5 Myr, slightly older than the previously computed median age (Luhman 2007).”
Analytical Theory for the Initial Mass Function: CO Clumps and Prestellar Cores (2008, background): “Expected Dependence of the Peak Position in the Cloud Mass One surprising piece of observational evidence is that the peak of the IMF is fairly constant from one region to another (e.g., Chabrier 2003a, 2005; Luhman 2004, 2007; Moraux et al. 2005).”
THE DISK POPULATION OF THE TAURUS STAR-FORMING REGION (2009, methodology): “Given that Chamaeleon I, IC 348, and σ Ori have similar ages (2–3 Myr, Luhman 2007; Luhman et al. 2008b), these differences in disk fractions are presumably tied to the star-forming conditions of these regions.”
The importance of radiative feedback for the stellar initial mass function (2008, background): “In particular, it is now generally accepted that the number of stars is larger than the number of brown dwarfs (Chabrier 2003; Greissl et al. 2007; Luhman 2007; Andersen et al. 2008).”
FURTHER DEFINING SPECTRAL TYPE “Y” AND EXPLORING THE LOW-MASS END OF THE FIELD BROWN DWARF MASS FUNCTION (2012, result): “Luhman (2007) compare results in Taurus, Chamaeleon I, IC 348, and the Trapezium Cluster to conclude that an initial mass function with slope α .”
Dust Evolution and the Formation of Planetesimals (2016, background): “…with ages from 1Myr to tens of Myrs have been surveyed by various projects with Spitzer (e.g. Allen et al. 2004; Megeath et al. 2004; Luhman 2007; Evans et al. 2009; Gutermuth et al. 2009; Fang et al. 2009; Luhman et al. 2010; Megeath et al. 2012; Fang et al. 2013; Sicilia-Aguilar…”
BANYAN. VII. A NEW POPULATION OF YOUNG SUBSTELLAR CANDIDATE MEMBERS OF NEARBY MOVING GROUPS FROM THE BASS SURVEY (2015, background): “2MASS J11335700–7807240 was identified by Luhman (2007) in the optical as an M8 dwarf in a search for new members of the Chamaeleon I (CHA) star-forming region.”
The Disk Population of the Chamaeleon I Star-forming Region (2008, methodology): “The census from Luhman (2007) did not include protostellar sources that have been detected only at far-IR wavelengths and longward, such as Cha-MMS1 (Reipurth et al. 1996).”
The Formation and Early Evolution of Low-Mass Stars and Brown Dwarfs (2012, background): “As noted above, no significant variations in these slopes are apparent in published IMFs for young clusters (NBD/Nstar ∼ 0.2, Andersen et al. 2006; Luhman 2007; Slesnick, Hillenbrand & Carpenter 2004, references therein).”
Inverse dynamical population synthesis: Constraining the initial conditions of young stellar clusters by studying their binary populations (2012, background): “The total stellar mass in Cha I is about 100M⊙, most of it being contained within a radius of 1◦ (Luhman 2007), corresponding to 2.88 pc at the distance of Chamaeleon.”
AN INFRARED/X-RAY SURVEY FOR NEW MEMBERS OF THE TAURUS STAR-FORMING REGION (2009, methodology): “This variation in the IMF is illustrated in Figure 12, where we include mass functions for IC 348 and Chamaeleon I that were derived in the same manner as our measurement for Taurus (Luhman et al. 2003b; Luhman 2007).”