Herbig Ae/Be Stars in nearby OB Associations

By Jesús Hernández, N. Calvet, L. Hartmann, C. Briceño, A. Sicilia-Aguilar, P. Berlind. 2004

183 citations recorded by the source corpus.

We have carried out a study of the early-type stars in nearby OB associations spanning an age range of ∼3–16 Myr, with the aim of determining the fraction of stars that belong to the Herbig Ae/Be class. We studied the B, A, and F stars in the nearby (≤500 pc) OB associations Upper Scorpius, Perseus OB2, Lacerta OB1, and Orion OB1, with membership determined from Hipparcos data. We also included in our study the early-type stars in the Trumpler 37 cluster, part of the Cep OB2 association. We obtained spectra for 440 Hipparcos stars in these associations, from which we determined accurate spectral types, visual extinctions, effective temperatures, luminosities and masses, using Hipparcos photometry. Using colors corrected for reddening, we find that the Herbig Ae/Be stars and the classical Be (CBe) stars occupy clearly different regions in the JHK diagram. Thus, we use the location on the JHK diagram, as well as the presence of emission lines and of strong 12 μm flux relative to the visual, to identify the Herbig Ae/Be stars in the associations. We find that the Herbig Ae/Be stars constitute a small fraction of the early-type stellar population even in the younger associations. Comparing the data from associations with different ages and assuming that the near-infrared excess in the Herbig Ae/Be stars arises from optically thick dusty inner disks, we determined the evolution of the inner disk frequency with age. We find that the inner disk frequency in the age range 3–10 Myr in intermediate-mass stars is lower than that in the low-mass stars (<1 M⊙); in particular, it is a factor of ∼10 lower at ∼3 Myr. This indicates that the timescales for disk evolution are much shorter in the intermediate-mass stars, which could be a consequence of more efficient mechanisms of inner disk dispersal (viscous evolution, dust growth, and settling toward the midplane).

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/bfb8f90661dbf70ed70de83b47da64ba103374e8

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In Astronomy and Astrophysics

1. K. Luhman
2. Eric Mamajek
3. L. Hartmann
4. N. Calvet
5. L. Hillenbrand
6. J. Muzerolle
7. G. Herczeg
8. L. Testi

In Instrumentation

1. K. Luhman
2. Eric Mamajek
3. A. Natta
4. L. Testi
5. L. Hartmann
6. N. Calvet
7. Anders Johansen
8. M. Pecaut

Citations in the corpus

• A spectroscopic survey of Herbig Ae/Be stars with X-shooter – I. Stellar parameters and accretion rates (2015, unknown): “…Herbst & Shevchenko (1999), (f) van den Ancker et al. (2004), (g) Malfait et al. (1998), (h) Coulson & Walther (1995), (i) Mora et al. (2001), (j) Hernández et al. (2005), (k) Miroshnichenko et al. (2004), (l) Gray & Corbally (1998), (m) Baines et al. (2004), (n) Finkenzeller & Mundt (1984),…”
• A Spitzer View of Protoplanetary Disks in the γ Velorum Cluster (2008, background): “As it is also an emission-line star (Houk 1978; MacConnell 1981) and its 2MASS colors are similar than those observed in classical Be stars (Hernández et al. 2005), this excess is likely to be free-free emission in a hot envelope - that is, this is probably the excess of a classical Be star.”
• A REVISED AGE FOR UPPER SCORPIUS AND THE STAR FORMATION HISTORY AMONG THE F-TYPE MEMBERS OF THE SCORPIUS–CENTAURUS OB ASSOCIATION (2011, result): “AK Sco is the star to the right of the locus, and its position is similar to that of the Herbig Ae/Be stars in Hernández et al. (2005).”
• Accretion Rates in Herbig Ae stars (2006, methodology): “Spectral type and distance are compiled from the literature (e.g., van den Ancker et al. 1997, 1998; Testi et al. 1998; Meeus et al. 2001; Rodgers 2001; Hernandez et al. 2005, and references therein).”
• THE DISK POPULATION OF THE UPPER SCORPIUS ASSOCIATION (2012, methodology): “We note that HIP 81474 has been frequently treated as a Herbig Ae/Be star, but it lacks a clear detection of line emission (Hernández et al. 2005).”
• Spitzer Observations of the Orion OB1 Association: Disk Census in the Low-Mass Stars (2007, methodology): “…of disks is strongly dependent on the stellar mass, show- ing larger frequencies in the TTS mass range (spectral types K and M) than in stars with higher masses (Lada & Lada 1995; Sicilia-Aguilar et al. 2005; Hartmann 2005; Hernández et al. 2005; Carpenter et al. 2006; Briceño et al. 2007b).”
• A Spitzer Space Telescope Study of Disks in the Young σ Orionis Cluster (2007, background): “…for objects in the mass range of the T Tauri stars (TTSs; with spectral type K5 or later; Haisch et al. 2001; Hartmann 2005b; L. Hillenbrand et al. 2007, in preparation) to <3 Myr for objects in the mass range of the Herbig Ae/Be (HAeBe) stars (spectral type F5 or earlier; Hernández et al. 2005).”
• A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun (2010, background): “…reason we check our star sample for pre-main sequence stars and find 236 of them either in catalogues (Chauvin et al. 2010; Ducourant et al. 2005; Hernández et al. 2005; Wichmann et al. 2005; Valenti et al. 2003; Köhler et al. 2000; Neuhäuser et al. 2000; Teixeira et al. 2000; Bertout et al.…”
• A high-resolution spectropolarimetric survey of Herbig Ae/Be stars – I. Observations and measurements (2012, unknown): “…(ap) Montesinos et al. (2009); (aq) Hernández et al. (2004); (ar) Mora et al. (2004); (as) Fossati et al. (2009); (at) Miroshnichenko et al. (2004); (au) Hernández et al. (2005); (av) Bernabei et al. (2009); (aw) Hillenbrand et al. (1992); (ax) Mora et al. (2002); (ay) Mora et al. (2001);…”
• Forming the cores of giant planets from the radial pebble flux in protoplanetary discs (2014, methodology): “For simplicity we will use here τdis = 3 Myr (Haisch et al. 2001), but disc lifetimes could be even shorter for stars above a solar mass (Hernández et al. 2005).”