Search for Transiting Exoplanets with HATNet Bakos, G. Á.; Noyes, R. W.; Kovács, G. ...
Proceedings of the International Astronomical Union,
05/2008, Letnik:
4, Številka:
S253
Journal Article
Recenzirano
Odprti dostop
HATNet is a network of six identical, fully automated wide field telescopes, four of which are located in Arizona, and two at Hawaii. The purpose of the network is to search for transiting extrasolar ...planets around relatively bright stars (8 < I < 12). The longitudinal coverage of 3.5 hours greatly enhances transit detection efficiency. HATNet has been operational since 2004, and has taken more than 1/2 million science frames at 5-min integrations, covering about 7% of the sky. Photometric precision reaches 3mmag rms at 5.5 min cadence at I ≈ 8, and is 1% at I ≈ 11.3. Hundreds of transit candidates have been detected in the data, and have been subject to vigorous follow-up by various 1m-class facilities, both spectroscopy and follow-up photometry. A fraction of the candidates that have survived these steps as not being false alarms have been observed by high resolution and precision spectrographs (primarily Keck/HIRES), to confirm their planetary nature and characterize their properties. So far nine transiting planets have been reported, making HATNet a very successful survey.
Gaia Early Data Release 3 Harrison, D L; Breedt, E; Wevers, T ...
Astronomy and astrophysics (Berlin),
08/2021, Letnik:
652
Journal Article
Recenzirano
Odprti dostop
Context. Since July 2014, the Gaia mission has been engaged in a high-spatial-resolution, time-resolved, precise, accurate astrometric, and photometric survey of the entire sky. Aims. We present the ...Gaia Science Alerts project, which has been in operation since 1 June 2016. We describe the system which has been developed to enable the discovery and publication of transient photometric events as seen by Gaia. Methods. We outline the data handling, timings, and performances, and we describe the transient detection algorithms and filtering procedures needed to manage the high false alarm rate. We identify two classes of events: (1) sources which are new to Gaia and (2) Gaia sources which have undergone a significant brightening or fading. Validation of the Gaia transit astrometry and photometry was performed, followed by testing of the source environment to minimise contamination from Solar System objects, bright stars, and fainter near-neighbours. Results. We show that the Gaia Science Alerts project suffers from very low contamination, that is there are very few false-positives. We find that the external completeness for supernovae, CE = 0.46, is dominated by the Gaia scanning law and the requirement of detections from both fields-of-view. Where we have two or more scans the internal completeness is CI = 0.79 at 3 arcsec or larger from the centres of galaxies, but it drops closer in, especially within 1 arcsec. Conclusions. The per-transit photometry for Gaia transients is precise to 1% at G = 13, and 3% at G = 19. The per-transit astrometry is accurate to 55 mas when compared to Gaia DR2. The Gaia Science Alerts project is one of the most homogeneous and productive transient surveys in operation, and it is the only survey which covers the whole sky at high spatial resolution (subarcsecond), including the Galactic plane and bulge.
The Type Ia Supernova 2001V in NGC 3987 Vinkó, J.; Bíró, I. B.; Csák, B. ...
Astronomy and astrophysics (Berlin),
01/2003, Letnik:
397, Številka:
1
Journal Article
Recenzirano
Odprti dostop
CCD photometry is presented of the type Ia SN 2001V occurred in the edge-on spiral galaxy NGC 3987. The observations made through Johnson-Cousins BVRI filters were collected from Feb. 24 ($t = - 8$ ...days, with respect to B-maximum), up to May 5 ($t = +62$ days). The light curves are analyzed with the revised Multi-Colour Light Curve Shape (MLCS) method (CITE) by fitting template vectors to the observed light curves simultaneously. The reddening of SN 2001V is estimated to be $E(B-V)=0.05$ mag, while the galactic component is $E(B-V) = 0.02$ mag (Schlegel et al. CITE), suggesting that part of the reddening may be due to the ISM in the host galaxy. The Δ parameter in MLCS converged to -0.47 mag, indicating that this SN was overluminous relative to the majority of Type Ia SNe. The inferred distance to its host galaxy, NGC 3987, is $74.5 \pm 5$ Mpc, which is in good agreement with recently determined kinematic distances, based on radial velocity corrected for Virgo-infall and Hubble constant $H_0 = 65$ km s-1Mpc-1.
We report the discovery of WTSib, the first extrasolar planet found by the WFCAM Transit Survey. For one of the most promising transiting candidates, high-resolution spectra taken at the Hobby-Eberly ...Telescope (HET) allowed us to estimate the spectroscopic parameters of the host star, a late-F main sequence dwarf (V = 16.13), and to measure its radial velocity variations. The combined analysis of the light curves and spectroscopic data resulted in an orbital period of the companion of 3.35 days, a planetary mass of 4.01 + or - 0.35M sub()J and a planetary radius of 1.49 super(+0.16) sub(-0.18) R sub()J WTSib has one of the largest radius anomalies among the known hot Jupiters in the mass range 3-5 M sub()J
We report the discovery of WTS1 b, the first extrasolar planet found by the WFCAM Transit Survey. For one of the most promising transiting candidates, high-resolution spectra taken at the ...Hobby-Eberly Telescope (HET) allowed us to estimate the spectroscopic parameters of the host star, a late-F main sequence dwarf (V = 16.13), and to measure its radial velocity variations. The combined analysis of the light curves and spectroscopic data resulted in an orbital period of the companion of 3.35 days, a planetary mass of 4.01 ± 0.35 MJ, and a planetary radius of 1.49 +0.16-0.18 RJ. WTS1 b has one of the largest radius anomalies among the known hot Jupiters in the mass range 3–5 MJ.
Hot Jupiters around M dwarfs Murgas F.; Martín E.; Koppenhoefer J. ...
EPJ Web of conferences,
04/2013, Letnik:
47
Journal Article
Recenzirano
Odprti dostop
The WFCAM Transit Survey (WTS) is a near-infrared transit survey running on the United Kingdom Infrared Telescope (UKIRT). We conduct Monte Carlo transit injection and detection simulations for short ...period (<10 day) Jupiter-sized planets to characterize the sensitivity of the survey. We investigate the recovery rate as a function of period and magnitude in 2 hypothetical star-planet cases: M0–2 + hot Jupiter, M2–4 + hot Jupiter. We find that the WTS lightcurves are very sensitive to the presence of Jupiter-sized short-period transiting planets around M dwarfs. The non-detection of a hot-Jupiter around an M dwarf by the WFCAM Transit Survey allows us to place a firm upper limit of 1.9 per cent (at 95 per cent confidence) on the planet occurrence rate.
The WHAT Project Shporer, A.; Bakos, G. Á.; Mazeh, T. ...
Proceedings of the International Astronomical Union,
05/2008, Letnik:
4, Številka:
S253
Journal Article
Recenzirano
Odprti dostop
WHAT is a small-aperture short focal length automated telescope with an 8.2° × 8.2° field of view, located at the Wise Observatory, Israel. The system is similar to the HATNet telescopes and is aimed ...at searching for transiting extrasolar planets and variable objects. Operational since 2004, WHAT has accumulated ~100000 exposures of several fields and was part of the discovery of the transiting planet HD147506b. Further description of WHAT can be found at: http://wise-obs.tau.ac.il/~what.
We report the discovery of WTS-2 b, an unusually close-in 1.02-d hot Jupiter (M
P
= 1.12M
J, R
P
= 1.30R
J) orbiting a K2V star, which has a possible gravitationally bound M-dwarf companion at 0.6 ...arcsec separation contributing ∼20 per cent of the total flux in the observed J-band light curve. The planet is only 1.5 times the separation from its host star at which it would be destroyed by Roche lobe overflow, and has a predicted remaining lifetime of just ∼40 Myr, assuming a tidal dissipation quality factor of
.
is a key factor in determining how frictional processes within a host star affect the orbital evolution of its companion giant planets, but it is currently poorly constrained by observations. We calculate that the orbital decay of WTS-2 b would correspond to a shift in its transit arrival time of T
shift ∼ 17 s after 15 yr assuming
. A shift less than this would place a direct observational constraint on the lower limit of
in this system. We also report a correction to the previously published expected T
shift for WASP-18 b, finding that T
shift = 356 s after 10 yr for
, which is much larger than the estimated 28 s quoted in WASP-18 b discovery paper. We attempted to constrain
via a study of the entire population of known transiting hot Jupiters, but our results were inconclusive, requiring a more detailed treatment of transit survey sensitivities at long periods. We conclude that the most informative and straightforward constraints on
will be obtained by direct observational measurements of the shift in transit arrival times in individual hot Jupiter systems. We show that this is achievable across the mass spectrum of exoplanet host stars within a decade, and will directly probe the effects of stellar interior structure on tidal dissipation.
PDF
