HFE 2 and L 43 - Two cold far-infrared sources

Nordh, H. L.; Vanduinen, Rj; Sargent, A. I.; Fridlund, M.; Aalders, J. W. G.

doi:10.1086/112885

Cited by 8 publications

(12 citation statements)

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“…In a census of Chamaeleon I, Luhman (2004a) assigned membership to a few objects that lacked spectroscopic classification but that exhibited mid-IR excess emission. One of these objects is ISO 13 (Nordh et al 1996;Persi et al 2000). The near-IR counterpart for ISO 13 was not positively identified in previous studies because of uncertainties in the coordinates measured with ISO.…”

Section: Remaining Candidatesmentioning

confidence: 99%

“…They detected 70 sources, half of which are cluster members. A mid-IR survey with better sensitivity and spatial resolution was later conducted with the Infrared Space Observatory (ISO, Nordh et al 1996;Persi et al 2000), which provided photometry for 99 known members, including a brown dwarf with a spectral type near M8 (Natta & Testi 2001;Apai et al 2002). Mid-IR imaging also has been performed toward smaller areas surrounding the three most prominent reflection nebulae in the Chamaeleon I cloud using IRAS (Assendorp et al 1990;Prusti et al 1991) and ISO (Lehtinen et al 2001).…”

Section: Introductionmentioning

confidence: 99%

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The Disk Population of the Chamaeleon I Star‐forming Region

Luhman

Allen

et al. 2008

ApJ

194

290

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We present a census of circumstellar disks in the Chamaeleon I star-forming region. Using the Infrared Array Camera and the Multiband Imaging Photometer onboard the Spitzer Space Telescope, we have obtained images of Chamaeleon I at 3.6, 4.5, 5.8, 8.0, and 24 µm. To search for new diskbearing members of the cluster, we have performed spectroscopy on objects that have red colors in these data. Through this work, we have discovered four new members of Chamaeleon I with spectral types of M4, M6, M7.5, and L0. The first three objects are highly embedded (A J ∼ 5) and reside near known protostars, indicating that they may be among the youngest low-mass sources in the cluster (τ < 1 Myr). The L0 source is the coolest known member of Chamaeleon I. Its luminosity implies a mass of 0.004-0.01 M ⊙ , making it the least massive brown dwarf for which a circumstellar disk has been reliably detected. To characterize the disk population in Chamaeleon I, we have classified the infrared spectral energy distributions of the 203 known members that are encompassed by the Spitzer images. Through these classifications, we find that the disk fraction in Chamaeleon I is roughly constant at ∼ 50% from 0.01 to 0.3 M ⊙ . These data are similar to the disk fraction of IC 348, which is a denser cluster at the same age as Chamaeleon I. However, the disk fraction at M 1 M ⊙ is significantly higher in Chamaeleon I than in IC 348 (65% vs. 20%), indicating longer disk lifetimes in Chamaeleon I for this mass range. Thus, low-density star-forming regions like Chamaeleon I may offer more time for planet formation around solar-type stars than denser clusters.

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Section: Remaining Candidatesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Disk Population of the Chamaeleon I Star‐forming Region

Luhman

Allen

et al. 2008

ApJ

194

290

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“…For instance, Figure 16 presents 6.7 and 14.3 µm ISO photometry for stars that are determined to be members and field stars by the previous diagnostics in this section and for the remaining stars that lack the data for those diagnostics. In a diagram of this kind, field stars are well-separated from the young stars that exhibit IR excesses (Nordh et al 1996;Olofsson et al 1999;Persi et al 2000). Therefore, a color of m(6.7) − m(14.3) > 1 is taken as evidence of membership in this work.…”

Section: Confirmed Members and Field Starsmentioning

confidence: 99%

“…At a distance of 160-170 pc Wichmann et al 1998;Bertout et al 1999), the Chamaeleon I cloud complex is one of the nearest major sites of active star formation. A variety of methods have been used to identify members of Chamaeleon I, including monitoring of photometric variability at optical (Hoffmeister 1962) and infrared (IR) wavelengths, objective prism spectroscopy at Hα (Henize 1963;Mendoza 1972;Schwartz 1977;Hartigan 1993;, X-ray imaging with the Einstein Observatory (Feigelson & Kriss 1989) and the Röntgen Satellite (Feigelson et al 1993;Alcalá et al 1995Alcalá et al , 1997Comerón et al 2000), and near-to mid-IR photometry from ground-based telescopes (Hyland et al 1982;Jones et al 1985;Cambrésy et al 1998;Oasa et al 1999;Persi et al 2001;Carpenter et al 2002), the Infrared Astronomical Satellite (IRAS) Assendorp et al 1990;Prusti et al 1991;, and the Infrared Space Observatory (ISO) (Nordh et al 1996;Persi et al 1999Persi et al , 2000Comerón et al 2000;Lehtinen et al 2001). To measure spectral types and to check for signatures of youth and membership in the resulting candidate members, spectroscopy was employed by those authors and in subsequent followup work (Appenzeller 1977(Appenzeller , 1979Rydgren 1980;Appenzeller et al 1983;Walter 1992;Lawson et al 1996;Covino et al 1997;Gómez & Persi 2002;Saffe et al 2003).…”

Section: Introductionmentioning

confidence: 99%

A Census of the Chamaeleon I Star‐forming Region

Luhman

2004

ApJ

203

386

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I present a new census of the members of the Chamaeleon I star-forming region. Optical spectroscopy has been obtained for 179 objects that have been previously identified as possible members of the cluster, that lack either accurate spectral types or clear evidence of membership, and that are optically visible (I 18). I have used these spectroscopic data and all other available constraints to evaluate the spectral classifications and membership status of a total sample of 288 candidate members of Chamaeleon I that have appeared in published studies of the cluster. The latest census of Chamaeleon I now contains 158 members, 8 of which are later than M6 and thus are likely to be brown dwarfs. I find that many of the objects identified as members of Chamaeleon I in recent surveys are actually field stars. Meanwhile, 7 of 9 candidates discovered by Carpenter et al. (2002) are confirmed as members, one of which is the coolest known member of Chamaeleon I at a spectral type of M8 (∼ 0.03 M ⊙ ). I have estimated extinctions, luminosities, and effective temperatures for the members and used these data to construct an H-R diagram for the cluster. Chamaeleon I has a median age of ∼ 2 Myr according to evolutionary models, and hence is similar in age to IC 348 and is slightly older than Taurus (∼ 1 Myr). The measurement of an IMF for Chamaeleon I from this census is not possible because of the disparate methods with which the known members were originally selected, and must await an unbiased, magnitude-limited survey of the cluster.

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“…The H ii region S235 (Sharpless 1959) lies within this area. It is a region of massive star formation with a young stellar object at its centre, and it has several compact radio components within several arcmin (Nordh et al 1984;Felli et al 2006). Radio recombination line observations indicate a radial velocity of −24.5 ± 0.7 km s −1 (Paladini et al 2003).…”

Section: New Regions Of Anomalous Emissionmentioning

confidence: 99%

Planckearly results. XX. New light on anomalous microwave emission from spinning dust grains

Ade¹,

Aghanim²,

Arnaud³

et al. 2011

A&A

154

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Anomalous microwave emission (AME) has been observed by numerous experiments in the frequency range ∼10-60 GHz. Using Planck maps and multi-frequency ancillary data, we have constructed spectra for two known AME regions: the Perseus and ρ Ophiuchi molecular clouds. The spectra are well fitted by a combination of free-free radiation, cosmic microwave background, thermal dust, and electric dipole radiation from small spinning dust grains. The spinning dust spectra are the most precisely measured to date, and show the high frequency side clearly for the first time. The spectra have a peak in the range 20-40 GHz and are detected at high significances of 17.1σ for Perseus and 8.4σ for ρ Ophiuchi. In Perseus, spinning dust in the dense molecular gas can account for most of the AME; the low density atomic gas appears to play a minor role. In ρ Ophiuchi, the ∼30 GHz peak is dominated by dense molecular gas, but there is an indication of an extended tail at frequencies 50-100 GHz, which can be accounted for by irradiated low density atomic gas. The dust parameters are consistent with those derived from other measurements. We have also searched the Planck map at 28.5 GHz for candidate AME regions, by subtracting a simple model of the synchrotron, free-free, and thermal dust. We present spectra for two of the candidates; S140 and S235 are bright H ii regions that show evidence for AME, and are well fitted by spinning dust models.

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HFE 2 and L 43 - Two cold far-infrared sources

Cited by 8 publications

References 0 publications

The Disk Population of the Chamaeleon I Star‐forming Region

The Disk Population of the Chamaeleon I Star‐forming Region

A Census of the Chamaeleon I Star‐forming Region

Planckearly results. XX. New light on anomalous microwave emission from spinning dust grains

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