Near-Infrared Photometric Variability of Stars toward the Orion A Molecular Cloud

By J. Carpenter, L. Hillenbrand, M. Skrutskie. 2001

262 citations recorded by the source corpus.

We present an analysis of J, H, and Ks time-series photometry obtained with the southern 2MASS telescope over a 0.°84 × 6° region centered near the Trapezium region of the Orion Nebula cluster. These data are used to establish the near-infrared variability properties of pre–main-sequence stars in Orion on timescales of ∼1–36 days, ∼2 months, and ∼2 years. A total of 1235 near-infrared variable stars are identified, ∼93% of which are likely associated with the Orion A molecular cloud. The variable stars exhibit a diversity of photometric behavior with time, including cyclic fluctuations with periods up to 15 days, aperiodic day-to-day fluctuations, eclipses, slow drifts in brightness over 1 month or longer, colorless variability (within the noise limits of the data), stars that become redder as they fade, and stars that become bluer as they fade. The mean peak-to-peak amplitudes of the photometric fluctuations are ∼0.2 mag in each band, and 77% of the variable stars have color variations less than 0.05 mag. The more extreme stars in our sample have amplitudes as large as ∼2 mag and change in color by as much as ∼1 mag. The typical timescale of the photometric fluctuations is less than a few days, indicating that near-infrared variability results primarily from short-term processes. We examine rotational modulation of cool and hot starspots, variable obscuration from an inner circumstellar disk, and changes in the mass accretion rate and other physical properties in a circumstellar disk as possible physical origins of the near-infrared variability. Cool spots alone can explain the observed variability characteristics in ∼56%–77% of the stars, while the properties of the photometric fluctuations are more consistent with hot spots or extinction changes in at least 23% of the stars, and with variations in the disk mass accretion rate or inner disk radius in ∼1% of our sample. However, differences between the details of the observations and the details of variability predicted by hot-spot, extinction, and accretion disk models suggest either that another variability mechanism not considered here may be operative or that the observed variability represents the net results of several of these phenomena. Analysis of the star-count data indicates that the Orion Nebula cluster is part of a larger area of enhanced stellar surface density that extends over a 0.°4 × 2.°4 (3.4 pc × 20 pc) region containing ∼2700 stars brighter than Ks = 14 mag.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/c11cfcc77c3ed83c794a41e29f905849dbc3c6e3

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In Astronomy and Astrophysics

1. K. Luhman
2. L. Hartmann
3. L. Hillenbrand
4. P. Myers
5. S. Andrews
6. N. Calvet
7. Eric Mamajek
8. N. Evans II

In Spectroscopy

1. K. Luhman
2. P. Myers
3. L. Hartmann
4. D. Wilner
5. L. Allen
6. R. Gutermuth
7. S. Andrews
8. J. Muzerolle

Citations in the corpus

• CSI 2264: SIMULTANEOUS OPTICAL AND INFRARED LIGHT CURVES OF YOUNG DISK-BEARING STARS IN NGC 2264 WITH CoRoT and SPITZER—EVIDENCE FOR MULTIPLE ORIGINS OF VARIABILITY (2014, methodology): “…58089 Morelia, Michoacn, Mexico 30 European Space Agency, 8-10 rue Mario Nikis, F-75738 Paris Cedex 15, France models (e.g., Herbst et al. 1994, Carpenter et al. 2001, Scholz et al. 2009, Rice et al. 2012, Faesi et al. 2012) have noted photometric behavior that is largely consistent with…”
• Spitzer Observations of NGC 1333: A Study of Structure and Evolution in a Nearby Embedded Cluster (2007, unknown): “…of the standard 2MASS observations as part of the 2MASS extended mission, yielding approximately a 1 magnitude improvement in the data completeness limit and reducing measurement uncertainty for sources within a magnitude of the detection limit of the regular 2MASS data (Carpenter et al. 2001).”
• A Census of the Chamaeleon I Star-forming Region (2004, unknown): “…not obtained at the same time, the dominant source of error for most of these measurements is variability, which is typically ±10% for young stars (Carpenter et al. 2001) .1 16.07 0.76 0.40 12.48 · · · · · · T24 11 07 12.07 -76 32 23.2 12.62 0.96 0.54 9.38 · · · · · · CHXR 22E 11 07 13.30 -77 43…”
• Identification of New M Dwarfs in the Solar Neighborhood (2003, background): “Some of these have been identified by previous surveys (Carpenter et al. 2001; Craig et al. 1997; Fuhrmeister & Schmitt 2003; Koehler 2001; Li & Hu 1998; Li et al. 2000;MacConnell 1981;Massey 2002; Preibisch&Zinnecker 1999; Thompson et al. 1998; Zickgraf et al. 2003).”
• THE MASS DEPENDENCE BETWEEN PROTOPLANETARY DISKS AND THEIR STELLAR HOSTS (2013, methodology): “For the many other sources that do not have sufficient data available to measure 〈F(m)〉, we assign a mean σv term determined from this subset: σ̄v = 0.33mags in B, 0.25mags in V and R, and 0.11mags in I.8 Near-infrared variability studies are rare for Taurus sources, so we adopt the results of a sim”
• X-Ray-emitting Young Stars in the Orion Nebula (2002, methodology): “%) have JHK but no optical counterparts (Hillenbrand & Carpenter 2000; Carpenter et al. 2001), one has only a mid-infrared counterpart, and 101 (9”
• THE SPITZER SPACE TELESCOPE SURVEY OF THE ORION A AND B MOLECULAR CLOUDS. I. A CENSUS OF DUSTY YOUNG STELLAR OBJECTS AND A STUDY OF THEIR MID-INFRARED VARIABILITY (2012, methodology): “We have adapted the Stetson analysis outlined in the 2MASS variability study of Carpenter et al. (2001) to the IRAC 3.6 and 4.5 μm bands.”
• THE TAURUS SPITZER SURVEY: NEW CANDIDATE TAURUS MEMBERS SELECTED USING SENSITIVE MID-INFRARED PHOTOMETRY (2009, background): “…but are not limited to X-ray surveys (e.g., Alcalá et al. 1996, Wolk et al. 2006), Hα surveys (e.g., Ogura et al. 2002), variability surveys (e.g., Carpenter et al. 2001, Rebull 2001), ultraviolet (UV) surveys (e.g., Rebull et al. 2000), and infrared (IR) surveys (e.g., Jørgensen et al. 2006,…”
• YSOVAR: THE FIRST SENSITIVE, WIDE-AREA, MID-INFRARED PHOTOMETRIC MONITORING OF THE ORION NEBULA CLUSTER (2011, methodology): “…by X-ray studies (Getman et al. 2005), d) has Hα profiles typical of weak-lined T Tauris (WTTs) (Tobin et al. 2009; Fűrész et al. 2008), e) has been labeled as variable by Carpenter et al. (2001), or f) finally we have included all the sources that have been claimed to be periodic variables.”
• ACCRETION RATES FOR T TAURI STARS USING NEARLY SIMULTANEOUS ULTRAVIOLET AND OPTICAL SPECTRA (2013, background): “Variable accretion hot spots can also affect the colors of the star, affecting the AV determinations (Carpenter et al. 2001, 2002).”